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Effects of Marine Reserve Characteristics on the Protection of Fish Populations: a Meta-Analysis
Journal of Fish Biology
Abstract
Meta-analyses of published data for 19 marine reserves reveal that marine protected areas enhance species richness consistently, but their effect on fish abundance is more variable. Overall, there was a slight (11%) but significant increase in fish species number inside marine reserves, with all reserves sharing a common effect. There was a substantial but non-significant increase in overall fish abundance inside marine reserves compared to adjacent, non-reserve areas. When only species that are the target of fisheries were considered, fish abundance was significantly higher (by 28%) within reserve boundaries. Marine reserves vary significantly in the extent and direction of their response. This variability in relative abundance was not attributable to differences in survey methodology among studies, nor correlated with reserve characteristics such as reserve area, years since protection, latitude nor species diversity. The effectiveness of marine reserves in enhancing fish abundance may be largely related to the intensity of exploitation outside reserve boundaries and to the composition of the fish community within boundaries. It is recommended that studies of marine reserve effectiveness should routinely report fishing intensity, effectiveness of enforcement and habitat characteristics.
... Despite the potential issues surrounding NTMR meta-analyses, it would appear that many of the findings of the current study are consistent with the large-scale meta-analysis findings. Meta-analysis studies have generally found strong effects of NTMR on rocky reef fishes (Mosquera et al. 2000, Côt e et al. 2001, Halpern and Warner 2002, Halpern 2003, Micheli et al. 2004, Guidetti and Sala 2007, Claudet et al. 2008, Giakoumi et al. 2017. The current study involving the systematic surveying of rocky reef fishes over large-spatial scales across a coherent network of marine parks also supports these general findings of major effects associated with NTMR. ...
... The current study involving the systematic surveying of rocky reef fishes over large-spatial scales across a coherent network of marine parks also supports these general findings of major effects associated with NTMR. Nonetheless, meta-analyses have consistently reported substantial variation among locations and studies in NTMR effects (Côt e et al. 2001, Guidetti and Sala 2007, Claudet et al. 2008). Despite the substantial variation in relative abundances among bioregions observed in the current study, the relative effects (and effect size ratios) were generally very similar. ...
... In large part, this variation in relative abundance is expected in the fish assemblages and species abundances across latitudes, but as observed in many meta-analyses the relative effects of NTMR indicate that latitude has little to no influence on the relative effects of NTMR (Côt e e al. 2001, Lester et al. 2009) and the responses were remarkably consistent, as they were in our study. Meta-analysis studies have generally found that effects only occur for targeted fish species, and few indirect effects have been observed for non-target fish species (Mosquera et al. 2000, Côt e e al. 2001, Micheli et al. 2004, Claudet et al. 2008. The same results were also found in our study. ...
Worldwide, several countries have established coherent, representative, and large-scale networks of marine reserves to conserve biodiversity. Very few have, however, published systematic assessments of the ecological responses to this network protection, hindering broad understanding of their generality, utility, and efficacy. We present data collected from systematic sampling of rocky reef fish assemblages at sites across a network of 27 no-take marine reserve areas (NTMR) and 27 partially protected areas (PPA) nested within multiple marine parks (regional networks) across three Australian bioregions
spanning >1000 km of coastline (7° latitude) to test the generality of ecological change across this network. We also sampled 18 reference areas (outside of the marine parks) to provide an independent assessment of potential NTMR effects and also to assess whole marine park effects. Baited remote underwater video (BRUV) was used to sample fishes between depths of 20–40 m over austral winters in four years (2010, 2011, 2015, and 2016). Despite substantial bioregional differences in fish assemblages, large and consistent effects of NTMR protection were detected across all bioregions for a key commercially and recreationally harvested species, Chrysophrys auratus (pink snapper). There were substantial increases in relative abundance of C. auratus in NTMR compared with fished zones through time (effect sizes >150%). The wider assemblage of targeted fish (excluding C. auratus) only showed relatively small effects of protection (~11%) with trends observed for site-attached wrasses (labrids) and planktivores (e.g., commercially
fished Scorpis lineolata) that are recreationally and commercially harvested. Furthermore, the relative abundance of non-target or by-catch species generally did not differ among management zones across the bioregional network. These results highlight how NTMR can be used to assess the ecological effects of fishing and wider environmental management, and can be incorporated into ecosystem-based management for reef species more generally. Importantly, the provision of robust evidence of the performance and generality of NTMR over large-spatial scales (e.g., bioregions) provides greater confidence in the expected outcomes from marine reserve networks as a conservation management approach.
... In line with evidence from Dinsdale & Harriott (2004), coral communities benefit from marine protection by increasing cover of reef building corals and reducing macroalgae cover that improves structural complexity (Mora 2009;Graham et al., 2013). It is speculated that MPAs enable commercially important, yet overexploited species such as the Spiny Lobster, Snapper, Grouper and Queen Conch to recover (Côté et al., 2001;Rudd & Tupper 2010;Horta e Costa et al., 2020). Previous research on MPA effectiveness found MPAs consistently support high total fish biomass than areas with no fishing restrictions (McClure et al., 2020) and fishing closures promote recovery of exploited fish species (Campbell et al., 2017). ...
... However, there is a lack of information regarding the current management of the MPA in Tela Bay, so it is important to consider that positive changes may not be present during this study, but this does not necessarily suggest the MPA will not succeed in the future. Côté et al., (2001) states quantifying the spatial and temporal changes in coral reef communities at a decadal scale can lead to a broader understanding of the changes and patterns within MPAs. This information may provide key information that contributes to effective management actions (Schutte et al., 2010). ...
... Kirkman et al., 2021;Lester et al., 2009;Micheli et al., 2004;Sale et al., 2005). Despite these promising results, the direction and magnitude of measured MPA effects depend on MPA parameters (Caselle et al., 2015;Côté et al., 2001), including reserve size (Claudet et al., 2008;Halpern, 2003;Parnell et al., 2006), spacing (Halpern & Warner, 2003;Shanks et al., 2003), shape (Kramer & Chapman, 1999), and age (Edgar et al., 2014;Molloy et al., 2009). Social factors, including level of enforcement (Gill et al., 2017;Guidetti et al., 2008;Turnbull et al., 2018), stakeholder support (Di Franco et al., 2016;Walmsley & White, 2003), and intensity of fishing pressure in surrounding areas (Ziegler et al., 2022), can also influence the effectiveness of MPAs. ...
... However, our findings for MPA size (length of protected shoreline) contradict previous findings for surf zone fish that report the benefits of large reserves (>1.5 km of beach frontage [Ortodossi et al., 2019]). Some studies also report minimal effects of MPA size (Côté et al., 2001;Guidetti & Sala, 2007;Halpern, 2003), whereas others demonstrate that the effects of protection from fishing are stronger in larger MPAs (Claudet et al., 2008), including those in deeper rocky habitats in California (Ziegler et al., 2024). Instead, we observed that the influence of region overshadowed the influences of MPA characteristics and habitat availability for surf zone fish ecosystems in California. ...
Marine protected areas (MPAs) globally serve conservation and fisheries management goals, generating positive effects in some marine ecosystems. Surf zones and sandy beaches, critical ecotones bridging land and sea, play a pivotal role in the life cycles of numerous fish species and serve as prime areas for subsistence and recreational fishing. Despite their significance, these areas remain understudied when evaluating the effects of MPAs. We compared surf zone fish assemblages inside and outside MPAs across 3 bioregions in California (USA). Using seines and baited remote underwater videos (BRUVs), we found differences in surf zone fish inside and outside MPAs in one region. Inside south region MPAs, we observed higher abundance (Tukey's honest significant difference [HSD] = 0.83, p = 0.0001) and richness (HSD = 0.22, p = 0.0001) in BRUVs and greater biomass (HSD = 0.32, p = 0.0002) in seine surveys compared with reference sites. Selected live‐bearing, fished taxa were positively affected by MPAs. Elasmobranchs displayed greater abundance in BRUV surveys and higher biomass in seine surveys inside south region MPAs (HSD = 0.35, p = 0.0003 and HSD = 0.23, p = 0.008, respectively). Although we observed no overall MPA signal for Embiotocidae, abundances of juvenile and large adult barred surfperch (Amphistichus argenteus), the most abundant fished species, were higher inside MPAs (K–S test D = 0.19, p < 0.0001). Influence of habitat characteristics on MPA performance indicated surf zone width was positively associated with fish abundance and biomass but negatively associated with richness. The south region had the largest positive effect size on all MPA performance metrics. Our findings underscored the variability in species richness and composition across regions and survey methods that significantly affected differences observed inside and outside MPAs. A comprehensive assessment of MPA performance should consider specific taxa, their distribution, and the effects of habitat factors and geography.
... This is compounded by sex ratios that overwhelmingly favour males, with implications for egg production. Marine reserves can theoretically function as 'controls' to assess the impact of fishing and anthropogenic interference on ecosystems (Russ and Alcala 1996b; Pande Ferguson et al. 2016), although this assumes that the exploitation of fish outside does not affect fish inside the reserve (Côté et al. 2001). Ideally, a marine reserve should be set up before the area is exploited although this is seldom the case (Halpern 2003). ...
... A metanalysis of New Zealand marine reserves found no relationship between blue cod size or abundance, and the size of the reserve or the time since establishment (Pande et al. 2008), as did the GLM analyses in this study. Similar metanalyses studies on a range of other species support this finding (Côté et al. 2001;Halpern 2003), whereas Malcolm et al. (2016) concluded that size and age were important variables affecting fish abundance. This strongly suggests that when designing and implementing a new marine reserve, location may be more important than size for blue cod, and relying on the passage of time to produce the desired outcomes for individual species is not guaranteed. ...
... Throughout the world, studies on MPA effects have shown a similar variety of responses from fish communities, including showing population increases within MPAs through time (Claudet et al., 2006;Thompson et al., 2017;Young and Carr, 2015), little change through time (Denny and Babcock, 2004) or variable responses (Dufour et al., 1995). MPAs also tend to have more pronounced affects on species that are targeted by fisheries compared to those that are not (Côté et al., 2001). In Victoria, the most targeted fishery species are found in the higher carnivore group, which tend to have greater home ranges and are less likely to benefit from protection within MPA boundaries. ...
... Statewide assessment of Victorian marine protected areas using existing data Size of MPAs is one of the basic parameters to be considered when designing a protected area; it is predicted to have an effect on how well the MPA works at preserving or increasing biodiversity Hastings and Botsford, 2003;Roberts et al., 2003). Although some studies have found that larger MPAs are not always more effective (Côté et al., 2001;Halpern, 2003), more extensive studies across a greater number of MPAs has shown that larger sizes result in greater effectiveness at increasing diversity within their MPA boundaries (Claudet et al., 2008;Edgar et al., 2014). ...
Parks Victoria Technical Series Number 118
... 2013). Although responses to protection are highly variable among fish taxa (Côté et al. 2001), MPAs have been shown to effectively increase abundance and biomass of larger fish species vulnerable to fishing practices (e.g. Russ 1985Russ , 2002García-Rubies and Zabala 1990;Harmelin et al. 1995;Letourneur 1996;Rakitin and Kramer 1996;Côté et al. 2001). ...
... Although responses to protection are highly variable among fish taxa (Côté et al. 2001), MPAs have been shown to effectively increase abundance and biomass of larger fish species vulnerable to fishing practices (e.g. Russ 1985Russ , 2002García-Rubies and Zabala 1990;Harmelin et al. 1995;Letourneur 1996;Rakitin and Kramer 1996;Côté et al. 2001). This was observed at Ningaloo Reef, with predatory fish biomass being significantly higher in sanctuary than in non-sanctuary zones. ...
Sea urchins can play a critical ecological role in the functioning of marine benthic ecosystems, mediating competitive interactions between corals and algae. Yet, little is known about factors affecting urchin distribution in intact coral reef systems. This study aims to determine the spatial distribution of two sympatric urchin species, Echinometra mathaei and Echinostrephus molaris, and potential factors contributing to this, within the intact coral reef system of Ningaloo Marine Park, north-western Western Australia. Benthic photographs and surveys were conducted on SCUBA at 126 sites across the Park to determine urchin presence, rugosity, substrate cover, water velocity, and fish predation for each site. Generalised additive models found that E. mathaei presence was positively related to algal cover, rugosity and non-sanctuary zones, suggesting that distribution may be driven by foraging behaviour, habitat complexity and predation. Echinostrephus molaris presence was positively related to habitat and region, suggesting its distribution may be largely driven by hydrodynamics, feeding strategy and regional variation. This study highlighted species-habitat associations and the complexities of these in structuring urchin communities. Although occupying similar niches, the predominantly non-overlapping feeding preferences, and morphological and behavioural differences between E. mathaei and E. molaris enable these species to coexist within the intact reef system of Ningaloo Marine Park.
... En contexte méditerranéen, la complexité de mise en place de nouvelles aires protégées découle non seulement des enjeux écologiques très particuliers à chaque zone naturelle tels que la taille (Cote et al., 2001) et le recouvrement spatial (Mora & Sale, 2011), mais aussi de la diversité des régimes règlementaires en vigueur (Lester & Halpern, 2008), de la qualité d'application de la loi . ...
... This contrast in the outcomes of protected areas might be related to the differences in their characteristics such as size (Cote et al. 2001), position and spatial coverage with regards to conservation targets (Mora & Sale 2011), types of implemented regulations (Lester & Halpern 2008), quality of law enforcement , possibility that available information is biased by the tendency to publish significant results , and most of all, the lack of systematic and informative ecological and socioeconomic criteria and/or indicators that would be as much objective as possible to prioritize conservation initiatives and biodiversity offset schemes Quétier & Lavorel, 2011). This information remains though essential for assessing the overall role of protected areas in biodiversity conservation and identifying where protected areas need to be further integrated with other conservation efforts to achieve effective species and ecosystems conservation and reach optimal protection. ...
Dans le contexte Méditerranéen pluri-complexe, tant au niveau écologique que sociopolitique, la mise en place de zones protégées mobilise une grande diversité d’outils basés sur des réalités règlementaires, foncières, financières, scientifiques et techniques. L’accompagnement des décideurs dans la conception et la mise en place de réseaux d’aires protégées est donc nécessaire. Cette thèse est fondée sur le principe de priorisation des enjeux socio-écologiques de conservation pour une orientation pertinente des options de protection dans les régions du pourtour méditerranéen. Elle s’appuie sur l’exemple précis du Liban, où les initiatives de protection demeurent jusqu’à ce jour peu adaptées aux besoins écologiques de conservation, et semblent guidées par une réponse à des enjeux socio-politique locaux qui priment sur les enjeux écologiques. Le but est de proposer une démarche objective, basée sur une combinaison de descripteurs écologiques et socio-économiques, qui permettrait une orientation réfléchie et adaptée pour la future désignation des aires protégées. Ainsi, sur base d’une revue bibliographique, des descripteurs complémentaires, non redondants, faciles à renseigner, et adaptés au contexte méditerranéen, ont été identifiés (avec leurs modalités, leurs valeurs et leurs variantes). A partir de ceux-ci nous avons élaboré un outil de support à la décision (MedConserve) qui permet de structurer les priorités de conservation de la biodiversité en utilisant les meilleures connaissances disponibles. Cet outil, testé sur plusieurs sites au Liban, propose différentes alternatives de protection priorisées, parmi lesquelles l’utilisateur (ministère, municipalité, région, etc.) serait en mesure de choisir la plus appropriée en fonction du contexte sociopolitique prévalent. Ceci met l’accent sur la forte dimension politique dans la conservation, dans la mesure où, même si l’objectif est de fournir un outil pour la désignation des aires protégées, les véritables défis se situeront ensuite au niveau des choix et des décisions d’ordre politique.
... More broadly, although with a limited sample size, we did not find support for the role of marine protected areas (MPAs) in offering resilience for invertebrates during marine heatwaves, as species responded in the same way at sites within and outside MPAs. Although MPAs can increase the biodiversity in fish populations (Côté et al. 2001) and increase the resilience of marine systems and communities to stress (Bellwood et al. 2004;Hughes et al. 2010;Roberts et al. 2017;West and Salm 2003), our findings support Bruno et al. (2019) who report a lack of evidence for managed resilience across many studies. This may be due to the magnitude of the heat event where the "Blob" and El Niño events combined. ...
Aim
Ecological “bright spots” remain resilient following climate events such as marine heatwaves. One explanation for resilience is that small‐scale variability in ocean temperature sustains cooler areas that emerge as local bright spots. In cases where foundational species like kelp thrive through marine heatwaves, the species that rely on kelp for habitat and food also benefit. Here, we test the effect of temperature and habitat loss across both space and time on marine invertebrate communities.
Location
The Channel Islands National Park in Southern California.
Methods
We use 25 years (1995–2019) of the National Park Service Kelp Forest Monitoring program surveys, focusing on permanent transects at 16 sites (including some within marine protected areas) that recorded the abundance of 30 kelp forest invertebrates, and include two major marine heatwave events (1997–1998 El Niño event and 2014–2016 combined “Blob” and El Niño event). We examine the effect of local in situ temperature and kelp cover on local diversity and drivers of abrupt diversity changes within the invertebrate communities.
Results
Sites with more kelp cover and lower local temperatures supported more even invertebrate communities. Additionally, we show evidence of a major state shift within the invertebrate communities during the “Blob” event where local ocean temperatures at surveyed sites better predicted the presence of species density shifts than kelp cover did. Cooler sites underwent more abrupt changes in invertebrate abundance, with these changes resulting in increases of warm‐affinity urchin species that prevented kelp recovery after the “Blob” resided.
Main Conclusions
We show that changes in kelp forest communities did not occur gradually, but through abrupt invertebrate abundance shifts even in protected areas. Contrary to expectations, we found some species benefitted from marine heatwaves, highlighting the importance of examining species‐specific responses in improving our understanding of how communities respond to environmental changes and marine heatwaves.
... In coastal and marine sites, the prevalence of marine protected areas (MPA) where fishing is either fully (no-take areas) or partially controlled (e.g., through specific gear regulations or bans on fishing in certain times of the year) are useful environments to examine systematic impacts of fisheries exploitation on fish density and behavioral traits (Agardy 1994;Januchowski-Hartley et al. 2011Alós, Puiggrós, et al. 2015;Sbragaglia et al. 2018;Bergström, Eggertsen, Ovegård, et al. 2022;Eklöf et al. 2023). Fish abundance and size are often higher in areas where fishing pressure is reduced because harvesting systematically impacts abundance (Côté, Mosqueira, and Reynolds 2001;Ojeda-Martínez et al. 2007;Lester et al. 2009;Edgar et al. 2014) and longevity of fishes (Ferreira and Russ 1996;Taylor and McIlwain 2010;Barnett et al. 2017). Studying behavioral impacts of exploitation is less common, but pairs of areas open or closed to fishing offer suitable arenas, particularly for species with confined home ranges exposed to recreational angling or spearfishing Januchowski-Hartley, Cinner, and Graham 2014;Alós, Puiggrós, et al. 2015;Bergseth et al. 2016;Colefax, Haywood, and Tibbetts 2016;Tsuboi et al. 2016;Feary, Fowler, and Booth 2024). ...
Controlled experiments have shown that northern pike ( Esox lucius ) is able to develop lure avoidance, but whether such patterns exist in the wild is unknown. We assessed the impact of recreational fishing on a natural population of pike in the southern Baltic Sea, from samples of three pairs of partially protected areas (pMPA) and nearby unprotected sites. Pike were 2–4 times more abundant inside pMPAs than outside in sites open to fishing. The mean size of pike was not greater in pMPAs, but protected sites hosted more exceptionally large fish than sites open to fishing. Pike in sites with reduced recreational fishing effort were more aggressive to artificial lures. About one‐third of the catch rate differences among pMPAs and open sites could be attributed to lure shyness. Collectively, our work shows that recreational fisheries exploitation of coastal pike reduced abundance, truncated the size structure of the largest individuals, and contributed to fisheries‐induced timidity through reduced reactivity to lures.
... Regulating recreational boats to minimize interactions with cetaceans and overseeing industrial activities and discharges are also pivotal measures for marine conservation within this MPA. Likewise, research and conservation endeavors must be regulated and periodically evaluated(Mcwhinnie et al., 2018;De Oliveira et al., 2019;Parente et al., 2017; Ministério do Meio Ambiente MMA, 2002; Instituto Chico Mendes de Conservação da Biodiversidade ICMBIO; Centro Nacional de Pesquisa e Conservação de Mamíferos AquáticosCentro de Mamíferos Aquáticos CMA, 2019;Côté et al., 2001). ...
Cetaceans inhabit oceans worldwide, coexisting amidst the growing intensity of human activities in the aquatic environment, particularly motorized vessel traffic. Understanding spatial correlations is essential for devising appropriate responses to these impacts. Hence, this project delved into the spatial relationship between cetacean distribution and marine traffic activities in the Santos Basin, Brazil. Data from two different databases were collected: one detailing cetacean distribution and the other to documenting various types of marine traffic in general. A total of 2352 cetacean records and 718777 vessel records were obtained. Subsequently, Structural Similarity analyses were carried out to identify niche overlap, yielding a result of 0.88. Addition, analysis utilizing the Nearest Neighbor method and Kernel density were employed, to pinpoint overlapping records of marine traffic with cetaceans, generating heat maps. These findings facilitated the identification of the areas where marine traffic intersects with cetacean habitats, leading to the proposal of both mandatory and voluntary conservation strategies. Key recommendations include speed reduction and voluntary exclusion zones. It is anticipated that the implementation of these strategies in the study area will aid in the conservation of cetaceans and the broader biodiversity of Brazilian Marine Protected Areas.
... As anticipated, the more complex sanctuary oyster habitat was associated with greater macrofaunal abundance and richness compared to harvested oyster reefs, and macrofaunal abundance generally in creased with increasing salinity because the lower Bay is more hospitable to mobile macrofauna (Karp et al. 2018). Overall, these findings are consistent with previous studies that showed (1) MPAs or sanctuaries consistently enhance species richness (Côté et al. 2001) and faunal abundances of rocky reef communities (Edgar & Stuart-Smith 2009) relative to fished sites, and (2) across coastal foundation species, habitat complexity predicts fish abundance and assemblages (e.g. Charbonnel 2002, Orth et al. 2006, Taylor & Bushek 2008, Hunter & Sayer 2009, Darling et al. 2017. ...
No-take reserves and habitat restoration are important management tools for reversing the effects of fishing on coastal habitats, associated faunal assemblages, and host-parasite interactions. Populations of the eastern oyster Crassostrea virginica have declined by 99% in areas of Chesapeake Bay, USA, due to overharvesting, disease, and other factors, and are now the focus of extensive restoration efforts. We surveyed subtidal oyster reefs using classic quantitative approaches and emerging videography methods to contrast pairs of harvested reefs and reefs protected in subtidal no-take marine reserves (oyster sanctuaries) in the Choptank, Great Wicomico, and James River tributaries of Chesapeake Bay. Overall, sanctuary oyster reefs contained more intact habitats and communities. Relative to nearby harvested reefs, sanctuary reefs (1) contained higher densities of oysters, (2) held larger oysters of lower condition, (3) hosted stronger oyster-macroparasite (boring sponge [ Cliona spp.] and mud blister worm [ Polydora spp.]) interactions, (4) had more complex habitat, and (5) supported a greater richness and abundance of macrofauna. Oyster and mobile macrofauna abundance increased with salinity, whereas macroparasite pre-valence peaked at mesohaline (5-20 psu) sites. Our results suggest that restored, sanctuary-protected oyster reefs are beginning to rebound from the effects of >100 yr of intensive harvest, as indicated by increased oyster density, recovery of host-parasite interactions, improved habitat characteristics, and more mobile macrofauna. Additionally, these patterns, observed across the salinity gradient in Chesapeake Bay, reflect a widespread trend in aquatic ecology: relative to fished areas, unfished areas have more complex habitats and communities, larger and higher densities of hosts, and stronger host-parasite interactions.
... Recreational fishing has been a steadily increasing activity in recent decades, attracting more and more water sports enthusiasts. However, this activity can have a considerable impact on the marine ecosystem, causing a significant decline in biodiversity and fish abundance in fishing grounds, with potentially serious consequences for the marine environment (Côté et al., 2001;Cooke & Cowx, 2004Lewin et al., 2006), by altering species community structure, geographic distribution, disrupting habitats, and altering the size and age of fish populations by increasing juvenile mortality, which can lead to highly variable annual recruitment of stocks (Hsieh et al., 2006). This activity can thus affect non-target species, such as turtles, birds and marine mammals, through the use of non-selective fishing techniques, such as drift nets, which can cause significant damage to marine ecosystems by capturing non-target species as well as protected species (Michallet, 2007;Lewison et al., 2014;Scales et al., 2018). ...
The objective of this study is to evaluate the impact of recreational fishing on the marine ecosystem in the Mostaganem region, through the assessment of targeted and captured biodiversity, based on annual monitoring, using different statistical tools. The results show a wide range of species caught by boaters, with a total of 79 species belonging to 38 families and 24 orders, dominated by bony fish (86%).
Biodiversity varies seasonally, due to the opportunistic behavior of boaters in targeting species according to their availability in the fishing grounds by using different gears and techniques at different seasons of the year.
These boaters mainly target predators at high trophic level and high economic value, in order to maximize their income, which has negative effects on the top of the food chain, thereby creating a cascading effect on species at a lower trophic level. Thus, 12% of these species are classified as endangered or vulnerable, indicating considerable risks to fisheries resources and the marine ecosystem and its sustainability, suggesting effective management measures to ensure the sustainability of this recreational activity by minimizing environmental impacts.
... Marine reserves can cause biological responses (e.g., winners and losers responding to survival, growth, recruitment, etc.), but how quickly these effects occur in different ecoregions, communities, and species is unclear. Species and communities can take several different trajectories after establishing a MR, depending on various biological, environmental, location, and social factors 5,11,12 . For example, MRs can increase levels of density and biomass within 1-3 years on average after closure to fishery 13 . ...
Marine reserves (MRs) are implemented worldwide to protect, restore, and manage marine ecosystems and species. However, it is important to document the positive effects those marine reserves have on slow-growth, temperate invertebrates such as abalone. Abalone, Haliotis spp., are marine gastropods of high economic value extracted worldwide for decades, which has led to fisheries-driven population decreases. In this work, we focused on a case study and assessed the short-term (1–2 years) effects of marine reserves established and managed by a local fishing cooperative at Guadalupe Island, Mexico. We evaluated the population status of green abalone, H. fulgens, by conducting (1) an assessment of the green abalone population around Guadalupe Island through subtidal monitoring and (2) an evaluation of the effect of two recently established marine reserves on population parameters such as the increase in density (individuals·m²), biomass, number of aggregated abalone, egg production, and proportion of individuals bigger than 150 mm (minimum harvest size) compared to fished areas. To assess the population around Guadalupe Island, we surveyed 11,160 m² during 2020 and 2021. We recorded 2327 green abalones with a mean ± SE shell length of 135.978 ± 0.83 mm and a mean density of 0.21 ± 0.02 individuals·m². All variables were statistically higher at the MRs except for shell length in 2021. In this work, we report for the first time the green abalone population status at Guadalupe Island and a positive short-term biological response to community-based marine reserves. This study suggests that a network of MRs combined with good management could help abalone populations in the short term in Guadalupe Island, potentially leading to more sustainable fishing practices and social-ecological resilience.
... Diverse research demonstrated that fish numbers and sizes are growing in marine protected zones. (Côté et al., 2001;Roberts et al., 2001). ...
Biodiversity and well-functioning ecosystems provide natural solutions that foster resilience, thereby assisting society in adapting to the negative effects of climate change. Through conducting a thorough review on maintaining and restoring native ecosystems, agrobiodiversity, landscape connectivity, and protected areas, this project aims to achieve its objective. Biodiversity is the variety of all living organisms on the planet. To examine the role of biodiversity in climate change adaptation, 55 distinct sources, including 50 peer-reviewed publications and 5 books, were utilized. The current analysis identifies sustainable management of biodiversity as an essential climate change adaptation strategy because species and genetically diverse ecosystems have a greater capacity to adjust to climate change. Furthermore, such measures boost the climate change resilience of ecosystems. So that they can continue to provide ecosystem services, hence facilitating the supply of alternate means of subsistence in the face of climate change. Many of these studies assume that biodiversity and climate change are tightly interconnected due to their mutual impacts. For instance, human-induced climate change poses a threat to biodiversity, but biodiversity resources can mitigate the effects of climate change on populations and ecosystems. However, a large number of research also point to context-dependent adaptation techniques that can be either positive or harmful depending on the circumstances. The majority of research has been undertaken on the poorest or most vulnerable households, with a primary focus on small islands and mountains, whereas other ecosystem products have been mostly neglected. Consequently, an essential strategy for conserving biodiversity and human well-being entails measures that are kept flexible in order to better adapt human societies to climate change, as well as biodiversity education and training activities that are superior at distributing innovative techniques.
... Ongoing human pressures are often overlooked in CA monitoring frameworks, despite the fact that CAs can only be successful if regulated activities are mitigated and if non-regulated activities are not causing unforeseen impacts Gill et al., 2017). Marine CA monitoring instead has typically focused on measuring ecological performance to track the maintenance or improvement of biodiversity and fish stocks, primary goals of many CAs (Côté et al., 2001;Edgar et al., 2014). The main regulatory focus of marine CAs is to limit extractive impacts of fishing (Grorud-Colvert et al., 2021); we refer to all static, geographically defined areas with fishing restrictions as "conservation areas" (including Marine Protected Areas (MPA), which for Canada are those established under the Oceans Act, and other designated area types; see Iacarella et al., 2023). ...
Abstract Expansion of marine conservation areas (CA) necessitates resource‐efficient and achievable strategies for monitoring and evaluation of ongoing fishing activity at national levels. To demonstrate and explore such a strategy, we conducted the first extensive analysis of fishing activity within Canada's static, geographically defined marine CAs with fishing regulations (n = 264 areas). We used 8 years of Automatic Identification System data to estimate fishing effort across three oceans and conducted temporal and spatial comparisons specific to each CA's regulations and enactment date. We addressed questions on CA effectiveness, fishing displacement, fishing the line behavior, and relationships between fishing activity and spatial CA attributes. We estimated 22,000 h of fishing activity within CAs after enactments, 22% of which was identified as illegal. CA effectiveness appeared to be lowest for Atlantic CAs based on illegal fishing effort density within CAs. Fishing displacement and fishing the line was generally not apparent as buffer areas around CAs tended to already have higher fishing effort prior to enactments. CA effectiveness and responses to CAs varied considerably, as was visualized using timeseries plots and maps developed for each CA. Our evaluation of a nation's full suite of CAs provides managers with a foundation and approach for continued monitoring and reporting.
... Even if variation is substantial (five fold between minimum and maximum CPUE increase) and more empirical studies are necessary, these results should provide a base for other MPA studies through benefit transfer, or through calibration of the many existing bio-economic fishery models. Other observed effects were not valued, such as: (i) less variability on fish harvest per trip (Cote et al., 2001) and, (ii) larger-sized fish caught for villages with MPAs (Halpern and Warner, 2002). ...
La protection côtière est un service écosystémique (SE) des récifs coralliens extrêmement important, en particulier avec les impacts négatifs imminents et croissants du changement climatique mondial (GCC). Le SE de protection côtière n'a cependant pas retenu la même attention que celle portée à des SE plus « évidents » peut-être parce que les avantages du SE ne sont visibles que sur terre (pas en mer) et sont couplés à des défis dans son évaluation tels que la détermination précise du rôle du corail vivant dans la fourniture du service. Malgré ces défis, la contribution des récifs à la prestation des SE a été scientifiquement prouvée. Les récifs coralliens sont en déclin à l'échelle mondiale à cause des impacts locaux et mondiaux, exacerbés par un financement inadéquat et non durable de leur protection et gestion. Il est impératif que nous déterminions les méthodes les plus adaptées pour améliorer la santé des récifs, dans un monde où la situation est à la fois désastreuse et sensible au temps ; avec un délai estimé à moins de 50 ans pour agir. Un élément essentiel de toute solution est de savoir comment payer pour ces améliorations, à un moment où les méthodes de financement traditionnelles semblent insuffisantes et où un financement inadéquat est identifié comme un obstacle majeur au succès de la conservation. L'objectif de cette thèse est d'étudier des solutions à la fois écologiques et financières pour améliorer la santé des récifs coralliens et son SE de protection des côtes. Nous concentrons l'analyse sur la viabilité et le financement de récifs artificiels “gris-verts” avec des solutions de restauration des récifs coralliens visant à protéger les plages de l'érosion. Le chapitre 2. Du paper pose le « décor » des chapitres suivants. Les interventions écologiques et financières interviennent dans le cadre d'une Aire Marine Protégée (AMP). Le document a analysé les données de 2 nations insulaires et via des analyses coûts-avantages a fourni des preuves de l'attractivité de l'investissement dans les AMP pour protéger les SE. Le chapitre prochaine passe en revue ce que l'on sait de la protection côtière des récifs coralliens et détermine sa faisabilité pour un système de paiement pour les services écosystémiques (PSE). Au cours du processus, le rôle du corail vivant a été analysé et les actions de gestion identifiées qui pourraient améliorer la santé des récifs pour la prestation de services ont été identifiées. Ce document identifie la restauration des coraux comme une intervention clé pour la protection côtière et fournit la justification du chapitre 5. Le chapitre 5 explore plus en détail les moyens non publics de financement de la conservation marine via des investissements à impact et des financements mixtes. Ayant identifié qu'il est logique d'investir dans les AMP au chapitre 1, nous identifions le type de financement et proposons un mécanisme de financement pour l'investissement. Les sorties sont utilisées dans le chapitre 5Le chapitre 6 utilise les résultats des chapitres 4 et 5 et développe des solutions écologiques et financières pour la protection côtière. Dans cet article, nous démontrons l'impact positif de la restauration des récifs, proposons des options pour le faire et montrons l'additionnalité obtenue en utilisant de telles solutions basées sur la nature par rapport aux infrastructures grises traditionnelles pour atténuer l'érosion côtière. Le chapitre 7 synthétise les résultats des chapitres précédents et conclut que si la restauration n'est pas une solution « parfaite », c'est peut-être notre meilleure chance d'améliorer la santé des récifs pour la protection côtière. Le fardeau du financement de telles solutions - dont le coût varie considérablement - ne devrait pas incomber uniquement aux gouvernements et devrait être partagé avec le secteur privé, en particulier ceux qui bénéficient directement de la protection côtière.
... Therefore, marine protected reserves served an important safeguarding tool against specifically the targeted fish breed. They can increase and maintain fish populations, compared to other non-protected surroundings (Cote et al., 2005). ...
5.ULUSLARARASI ERCİYES
BİLİMSEL ARAŞTIRMALAR
KONGRESİ TAM METİN KİTABI
... Given the complexities of managing data-poor SSF in many locations, marine protected areas (MPAs) have become one of the more popular tools within ecosystem-based and/or integrated coastal management strategies (Cote, Mosqueira & Reynolds, 2001;Cinin-Sain & Belfiore, 2005;Edgar et al., 2014;Prince & Hordyk, 2019). This approach is based on the closed area concept (Beverton & Holt, 1957) with the inference that displacement of fishing effort may be more effective than control of catch or effort. ...
Many species targeted by multi‐gear small‐scale fisheries in developing countries are poorly studied in terms of fisheries sustainability even as their contributions to biodiversity, livelihoods, export earnings and food security are well documented.
This study presents new information on more than 150 fish species that constitute the bulk of small‐scale fishery landings in Belize and on the Pacific coast of Guatemala to provide guidance for improved biodiversity conservation and fisheries management. This includes a number of species listed as threatened on the IUCN Red List and Appendix II of CITES.
Simple, length‐based approaches and thresholds of size at maturity show that many of the elasmobranch and bony fish species examined have many immature individuals landed (Belize 51%, Guatemala 77%) across several gears.
In both countries, maximum size is negatively correlated with the intensity of overfishing for several common metrics: proportions of mature, optimal sized and mega‐spawners. The disproportionate removal of the largest species first will have cascading effects on biodiversity, community structure and species interactions, as well as livelihood opportunities and food security for fishing communities.
Status indicators, such as fishing mortality rate relative to natural mortality rate and estimates of depletion based on lengths are sensitive to the assumed values of life history parameters, indicating the importance of improved data on growth, maturity and mortality for these populations.
Our study emphasizes the use of a combination of fisheries conservation strategies, including size and effort controls, in conjunction with the closed area concept (i.e. marine protected areas) and meaningful consultation with resource users in order to maximize benefits for nature and people.
... επεκτείνονται ακόμη και πέρα από τα όρια της περιοχής (Halpern and Warner 2002, Halpern 2003, Gell and Roberts 2003. Αυτό συμβαίνει ανεξάρτητα από το μέγεθος της περιοχής (Côté et al. 2001, Halpern, 2003, ενώ αντιφατικά είναι τα αποτελέσματα σε σχέση με την παλαιότητα της Θ.Π.Π. (Mosquera et al. 2000, Halpern and Warner 2002, Micheli et al. 2004, Russ and Alcala 2004. ...
... What happens inside small-scale MPAs is important to understand their function in ecosystem maintenance and recovery (Di Lorenzo et al., 2016;Edgar et al., 2014;Lipcius et al., 2001;Russ 2002). The purposes of estimating the CME value for MPAs is to show that MPAs have value in their ability to safeguard the marine ecosystem, modeling their economic benefits on fishery effects, and the evaluation of other benefits such as those related to tourism and other businesses (Côté et al., 2001;Edgar et al., 2014;Forcada et al., 2008;Gell and Roberts 2003). These commercial and informal economic activities support the livelihoods of local populations through fishing, wild resources, recreation, and tourism (Barbier 2012). ...
Coastal marine resource over-exploitation has led to the loss of marine biodiversity and environmental degradation. This has serious consequences to Coastal and Marine Ecosystems (CME) and ecosystem services. Marine Protected Areas (MPAs) can have positive influences on adjacent fisheries and habitat recovery, which can help resolve these issues. However, quantifying the monetary value of an MPA's potential ecosystem service delivery is notoriously difficult. In this study, we review available tools for evaluating the monetary value of CME services for MPAs. We show that only four out of the 12 most frequently used CME tools incorporate monetary value assessments for MPAs, the rest of the tools can help build monetary awareness but only indirectly. We argue that the monetary value measurement of CME services for MPAs should be based on the biophysical production of services in MPAs rather than from subjective human perspectives (e.g., Willingness to Pay surveys). This requires transdisciplinary knowledge connecting ecology and economy, to produce an ecology-based monetary value measurement. We suggest that developing this novel method could help to better understand the valuation of CME services for MPAs and make a positive influence on marine conservation.
... Such a region is called a No-Take Area (NTA). The meta-analysis of [1] found that those species that were targeted by fisheries showed the most significant increase in abundance within MPAs. The effectiveness of these areas for species survival depends on their ecological suitability for fish reproduction, and on their size compared to the mobility of the fish. ...
... Such a region is called a No-Take Area (NTA). The meta-analysis of [1] found that those species that were targeted by fisheries showed the most significant increase in abundance within MPAs. The effectiveness of these areas for species survival depends on their ecological suitability for fish reproduction, and on their size compared to the mobility of the fish. ...
Sustainable natural resource management strategies are required to maintain a fishery. One common device is to designate a No-Take Area (NTA) or a less restrictive Marine Protected Area (MPA) within a fishery. In this work, exact time-dependent solutions to 2-D nonlinear reaction-diffusion equations of Fisher type are constructed to model the fish population density of a single species within an NTA. The spillover rate from an NTA, important for harvesters, has previously been calculated without allowing for spatial variation within the NTA. Here, that spatial dependence is incorporated in the calculation. Spatially-dependent and density-dependent diffusivity and birth rates are considered for linear, rectangular and circular geometries, the latter being the most efficient with minimal critical domain area. The effect of the spatial dependence of diffusivity and birth rates, common in fish populations where reproduction and protection are favoured towards the centre, on the minimum size of an exclusion zone that ensures species survival, is studied. It is shown that when any one of these factors is taken into account, the size of the critical domain decreases by a small amount.
... However, the results from previous meta-analyses on the effects of NTZ size on fish populations are mixed. While some found that rapid biological responses within NTZs were independent of reserve size, indicating that even small reserves can enhance populations of targeted species (e.g., Côté et al. 2001;Halpern & Warner 2002;Halpern 2003;Micheli et al. 2004), others found clear effects of reserve size (Claudet et al. 2008;Edgar et al. 2014). These different outcomes likely reflect the importance of a species mobility in relation to the NTZ size. ...
Areas closed to fishing year-round (no-take zones, NTZs) or during spawning time (spawning closures) are used as a management tool to increase declining fish populations. We evaluated the effects of a 147 km2 NTZ and a 3980 km2 spawning closure on whitefish populations in the northern Baltic Sea, and also accounted for fish consumption by seals and cormorants. Fish monitoring with multimesh gillnets in 2011–2016 showed a significant increase in catch per unit effort (CPUE) of mature whitefish (> 30 cm) both in the spawning closure and the NTZ compared with the reference area open to fishing. The rate of increase was significantly higher in the NTZ than in the spawning closure. Our results suggest that NTZs may strengthen coastal fish populations in temperate regions and that also seasonal closures under a critical period of the life cycle may benefit the populations.
... Although it is known that environmental variables (i.e., topographic complexity, wave exposure, benthic cover and depth) are important predictors of reef fish assemblages (Floeter et al., 2007;Gibran and Moura, 2012;Teixeira-Neves et al., 2015 and consequently sources of confounding factors to detect MPA outcomes (Claudet and Guidetti, 2010;Sciberras et al., 2013), in our results the level of protection was the most important variable to explain biomass variation of two targeted fish groups (Epinephelidae and Lutjanidae) and one non-targeted group (territorial herbivores). As expected, highly targeted fish species with higher trophic level and body size showed positive response to protection (Mosquera et al., 2000;Côté et al., 2001;Rolim et al., 2019), whereas territorial herbivores probably responded to lesser predator pressure in the open-access area. In contrast, the main predictor of biomass of the parrotfishes was coral cover followed by depth and island size. ...
Marine protected areas (MPAs) represent a useful tool for resource management, as well as to conserve and/or restore biological communities. The level of protection is key factor influencing the marine biodiversity, where a more enforced protection is expected to drive positive outcomes. In 2008, a large MPAs network ( 11,380 km 2)
was established in one of the the most populated and industrialized areas in the world (i.e., São Paulo State coast, southeast Brazil). Given many goods and services provided by marine ecosystems, this MPA network represents the most challenging marine conservation initiative in Brazil. Harboring areas with different socio-ecological contexts
and management regimes, this MPA network provides a unique opportunity to investigate the effects of cumulative impacts. We contrasted the biomass and size structure of reef fish in three subtropical islands under different levels of enforcement. We analyzed the influence of variables as island size, benthic cover, depth, topographic complexity, wave exposure, and protection level on the biomass of reef fish assemblages. Protection level was the main attribute responsible to explain the high biomass of fish target species and small territorial herbivores. In sites sheltered from the waves, the biomass of groupers was 1600% higher within enforced area than that from open-access area. Beyond the idea of positive effects of enforcement on reef fish biomass and size, we add evidences that even under multiple stressors, the area-based management is still a strong tool to marine conservation.
... La pression de pêche se concentre généralement aux limites extérieures des AMPs puisque ces dispositifs de conservation sont connus pour abriter de plus fortes biomasses et niveaux de richesse spécifique, notamment pour les espèces sédentaires (Lester et al., Synthèse| 106 2009). En revanche, les espèces mobiles ne profitent pas totalement des AMPs puisqu'ils peuvent être capturés à l'extérieur des limites (Cote et al., 2001;Lester et al., 2009). ...
Au-delà de la perte de richesse spécifique, les activités humaines entraînent probablement la diminution de la diversité phylogénétique et fonctionnelle portée par les espèces dans les communautés. Comprendre les effets des activités humaines sur l’ensemble des facettes de la biodiversité liées au fonctionnement des écosystèmes et évaluer les outils de conservation de ces facettes restent des enjeux majeurs de l’écologie notamment en milieu marin.Les objectifs de la thèse sont donc i) d’évaluer les impacts humaines sur la diversité des lignées phylogénétiques et des fonctions au sein des communautés de poissons coralliens indépendamment des facteurs environnementaux naturels, ii) d’évaluer la capacité des aires marines protégées à conserver efficacement ces facettes et à produire des valeurs de références pour la gestion des écosystèmes et iii) de mesurer la vulnérabilité fonctionnelle intrinsèque, sans pression humaine, des communautés de poissons.. Pour cela nous avons dû échantillonner des sites très isolés des populations humaines à travers l’Indopacifique et nous avons utilisé des modèles permettant de prendre en compte les effets de seuil et les interactions pour extraire les effets ‘purs’ liés à l’homme.Dans un premier temps, nous montrons, à l’échelle du Pacifique sud-ouest, que le nombre d’espèces des poissons perroquets diminue linéairement mais uniquement de 12% le long d’un gradient d’impact humain alors que les diversités phylogénétique et fonctionnelle diminuent de 36% et de 47%, respectivement, avec de forts effets de seuil.Dans un deuxième temps, en considérant un gradient d’impact humain et une large gamme d’aires marines protégées (AMPs) en Nouvelle-Calédonie, nous démontrons que les sites très isolés des activités humaines (>20 heures de temps de trajet depuis Nouméa la capitale régionale) possèdent des communautés de poissons avec une plus forte diversité fonctionnelle et biomasses de prédateurs apicaux que la plus grande et plus ancienne AMP intégrale.Finalement, en considérant quatre sites isolés des activités humaines à travers l’Indo-Pacifique, nous avons révélé que la diversité des fonctions portées par les poissons est très vulnérable, 60% n’étant portées que par une espèce, même sans impact humain.Nos travaux montrent la très forte vulnérabilité aux activités humaines des facettes fonctionnelles et phylogénétiques de la biodiversité, avec un manque de capacité des AMPs à restaurer l’ensemble des rôles fonctionnels des poissons et une redondance très limitée pour ces fonctions même dans les sites les plus isolés.
... Non-compliance is known to hinder management measures benefits(Byers & Noonburg, 2007;Edgar et al., 2014), and spatial ecology is related to the response of species to protectionDi Franco et al., 2018).In most of the analyses performed, the impact area showed higher levels of abundance and biomass throughout the experiment (in both periods, before and after). This is a common output in MPA assessments, since the most productive areas are usually selected for protected areas, owing to their particular habitat or assemblage quality(García-Charton & Ruzafa, 1999;Côté, Mosqueira & Reynolds, 2001).MPA restrictions are intended to reduce fishing mortality and increase individual longevity(Lester et al., 2009), resulting in a growing trend of commercial species' average TL, as seen in some of the populations studied (e.g. M. azevia, M. merluccius, and S. senegalensis).Although there was a >9% increase in R. clavata average TL, this increase was not statistically significant, most probably due to the low sample size.The average TL increase of most commercial species within the impact area, together with the decrease in abundance and biomass of legal-size commercial species within the control area, probably result in a larger spawning capacity of the impact-area population than in the control area. ...
• The implementation of marine protected areas (MPAs) has been widely used as a tool to manage and conserve marine resources and services. Yet, to date, the reserve effect is still weakly evaluated, particularly for soft‐sediment habitats.
• The Arrábida MPA, considered as a biodiversity hotspot, was fully established in 2009 on the west coast of Portugal and is characterized by large expanses of soft‐sediment habitats. This MPA was established to protect biodiversity and to ensure the livelihood of the local small‐scale fisheries community.
• Beyond before–after‐control–impact (BACI) analyses were carried out on catch data (abundance and biomass) of 351 trammel net sets from experimental fishing campaigns (2007–2019) to study the reserve effect on demersal fish populations.
• The results show a declining trend in abundance inside and outside the protected area, with significant positive effects only found for undersize commercial species and Solea senegalensis, and a general increase in fish species total length. Despite the lack of any obvious reserve effect, the increase in fish length can be considered as a first sign.
• Anthropogenic pressures are generalized around the area, and transgressions of the restrictions are frequently observed inside the no‐take zone. These can, among other aspects, delay or prevent the expected reserve effects. Therefore, enforcement and/or modification of the spatial plan must be incentivized to achieve the goals of the MPA.
... are several examples in which the effects of protection benefits have been identified through CST in the Mediterranean Sea (Guidetti & Sala, 2007;Guidetti et al., 2008;Hackradt et al., 2014;Sala & Giakoumi, 2017) and at a broader scale (Mosquera et al., 2000;Côté, Mosquera & Reynolds, 2001;Micheli, Halpern & Botsford, 2004;Edgar et al., 2014). Thus, if the purpose of the study is to compare different protection levels, any method may be suitable, although CST provides lower accuracy, and in many cases the high variability of the estimations may be too large to detect differences between treatments. ...
• Marine protected areas (MPAs) are used as fisheries management and conservation tools. Well‐enforced no‐take zones allow the rebuilding of natural populations of exploited species; however, there is still controversy on the role of buffer zones.
• The effectiveness of MPAs could be underestimated, as fish population assessments depend largely on traditional methodologies that have difficulties in detecting predatory fish because of their low abundances, their patchy distribution, and their reaction to the presence of divers.
• The performance of different census methods was compared in assessing the protection benefits for large predatory fishes under different protection levels (i.e. no‐take and buffer zones) in five Mediterranean MPAs. Specifically, conventional strip transects (CSTs, 50 × 5 m²) and tracked roaming transects combined with distance sampling (TRT + DS, variable lengths) were compared, including a series of TRT‐derived estimators with variable transect lengths and fixed widths of 20, 10, and 6 m (TRT20, TRT10, and TRT6, respectively). Additionally, the effectiveness of the MPAs studied and protection levels for conserving large predatory species was evaluated.
• Transects covering larger areas (i.e. TRT + DS and TRT20) allowed the detection of a greater number of species and yielded more accurate estimates of density and biomass than transects of narrower fixed widths, particularly the CSTs, which were associated with the lowest richness detection capability, accuracy, and precision. On average, both no‐take zones and buffer zones appeared effective for the conservation of predatory fishes, indicating that multiple protection areas were ecologically effective. Differences between MPAs were also observed, however, probably arising from both local environmental and management factors.
• We suggest the implementation of methodologies with larger transects for the study of large predatory fish, combined with CSTs for the rest of the fish community, in order to avoid biases in predatory population assessments, which are key indicators of MPA effectiveness.
SALT og Havforskningsinstituttet har på oppdrag fra Miljødirektoratet utarbeidet en «Kunnskapssyntese om virkninger av marine verneområder (MPA) for økosystemfunksjon og potensial for høsting i omkringliggende områder» (saksnummer 2024/3032). Med bakgrunn i Stortingsmeldingen «Heilskapleg nasjonal plan for bevaring av viktige område for marin natur» har regjeringen
et uttalt mål om å styrke kunnskapen om effekter av marine verneområder i Norge, og ønsker å få gjennomført en kunnskapssyntese om virkninger av marine verneområder for økosystemfunksjon og muligheter for høsting av levende ressurser i omkringliggende områder. --------------------------------------------SALT and the Institute of Marine Research have, on behalf of the Norwegian Environment Agency, prepared a "Knowledge synthesis on the effects of marine protected areas (MPA) on ecosystem function and potential for harvesting in surrounding areas" (case number 2024/3032). Based on the White Paper "Comprehensive national plan for the conservation of important areas for marine nature", the government has a stated goal of strengthening knowledge about the effects of marine protected areas in Norway, and wants to have a knowledge synthesis carried out on the effects of marine protected areas on ecosystem function and potential for harvesting living resources in surrounding areas.
The transboundary nature of marine ecosystems and their more difficult accessibility create challenges for the conceptualisation of effective marine conservation, because of the complexity of the marine functioning and often unclear competences. Marine conservation thus often relies on (international) policies. The EU environmental policies are known for their high ambition levels. However, their implementation has been subpar so far. This study investigates the viewpoints of marine nature, wilderness, and strict protection in the EU seas and whether those help explain why the implementation of EU marine environmental policies has been incoherent and uncoordinated so far. The viewpoints and nature imaginaries were investigated amongst key actors in policy implementation from national to the EU and Regional Sea Conventions levels, using policy analysis, diagramming, and Living Q workshops. The results show a variety of divergent viewpoints that frame marine issues in different ways, resulting in different interpretations of common policies and definitions, as well as a variety of policy implementation priorities. The variety of different values associated with marine nature, wilderness, and the role of EU policies is thus likely to influence the way common EU policies will be implemented in the future and by extension their effectiveness.
Na Amazônia brasileira, iniciativas comunitárias para regular a exploração dos lagos de pesca na várzea já tem uma história antiga (De Castro 1999). A natureza dessas iniciativas tem evoluído rapidamente desde 1960, quando a expansão da pesca comercial levou ao aumento dos conflitos entre pescadores comerciais itinerantes e pescadores locais residentes da várzea (McGrath et al. 1993, De Castro 1999, Oliveira & Cunha 2000, Pereira 2000, Smith 2000).Palavras-chave: Pescadores. Baixo Amazonas. Pesca.
Marine Protected Areas (MPAs) are essential tools in the protection and conservation of marine ecosystems. However, very few MPAs are effective and meet their conservation objectives mainly due to a lack of coordination, participation or resources. For instance, in the Mediterranean Sea there are about 1062 MPAs, but 72% of them do not have effective regulations to reduce human impacts on biodiversity and current efforts are insufficient in managing human uses for the conservation and protection of marine biodiversity. This makes necessary to seek new ways or instruments for their management. In this sense, digitalization and Information and Communication Technologies (ICT) can provide tools to facilitate the development of MPAs management in a more effective, participatory and efficient manner because automatic agents report their information and digest the data no matter the situation.
In the specific case of Spain, one of the main problems identified for MPAs management is the overlapping of different kinds of protected areas in the same territory. In addition, these are managed by different administrations (Regional, National). An example of this situation is the Sierra Helada Marine Natural Park (SHMP) in Alicante. Within its territorial scope there are 3 MPAs with different protection figures that overlap each other, SHMP, the Natura 2000 site of Serra Gelada i la Marina Baixa and a fishing protected area. These MPAs are managed by different regional governmental bodies, and have a natural resources action plan in use, supported by a management collaboration agreement with the town councils in the area and the Altea Nautical Club. In the SHMP, Posidonia oceanica (PO) is one of the most important ecosystems and its presence prompted its creation and declaration. PO is a marine angiosperm endemic to the Mediterranean Sea that forms extensive meadows from the sea surface to 30–40 m depth and which provides essential goods and services: it improves water quality and protect beaches against erosion. PO meadows are recognized as biodiversity hotspots, and as major carbon sinks, but they are very sensitive to human activities. However, although many regulations protect PO, there are still significant threats to their conservation.
In this regard, the research presented in this paper is the development of an ICT-based software tool, called Smart MPA, that includes an analysis framework based on management and governance indicators specific for PO and a database on PO that includes and combines different sources of information, including the results obtained of the evaluation of the analytical framework, input from information from citizens or MPA users, for example, by sending photos to report infractions in PO at specific points and from satellite images or underwater UAVs. The main objective of the Smart MPA tool is to offer services applied to PO management, either through the analysis of governance indicators or by facilitating the integration of citizen information to be used in management activities. The tool has been tested and used by the management staff of SHMP to be applied to an annual monitoring of management measures to develop an adaptive management of PO and the SHMP. After that, a semi-structured interview was carried out to collect information on the analytical framework co-developed and a survey was created where management staff of SHMP have given their perception on the usability of the tool and on the environmental problems affecting the conservation of PO in SHMP. According to the results obtained, the management of PO in SHMP is efficient, at a general level, with the lack of adequate funding being a limiting factor. The main threats are boat anchoring and organic pollution. In conclusion, the Smart MPA tool and the analytical framework are instruments that can facilitate the management and promote good environmental governance processes for the conservation of PO meadows in SHMP. At the same time, the importance of exploring mobile apps to increase citizen participation and mitigate threats and impacts on PO have been highlighted.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
The local diversity and global richness of coral reef fishes, along with the diversity manifested in their morphology, behaviour and ecology, provides fascinating and diverse opportunities for study. Reflecting the very latest research in a broad and ever-growing field, this comprehensive guide is a must-read for anyone interested in the ecology of fishes on coral reefs. Featuring contributions from leaders in the field, the 36 chapters cover the full spectrum of current research. They are presented in five parts, considering coral reef fishes in the context of ecology; patterns and processes; human intervention and impacts; conservation; and past and current debates. Beautifully illustrated in full-colour, this book is designed to summarise and help build upon current knowledge and to facilitate further research. It is an ideal resource for those new to the field as well as for experienced researchers.
The local diversity and global richness of coral reef fishes, along with the diversity manifested in their morphology, behaviour and ecology, provides fascinating and diverse opportunities for study. Reflecting the very latest research in a broad and ever-growing field, this comprehensive guide is a must-read for anyone interested in the ecology of fishes on coral reefs. Featuring contributions from leaders in the field, the 36 chapters cover the full spectrum of current research. They are presented in five parts, considering coral reef fishes in the context of ecology; patterns and processes; human intervention and impacts; conservation; and past and current debates. Beautifully illustrated in full-colour, this book is designed to summarise and help build upon current knowledge and to facilitate further research. It is an ideal resource for those new to the field as well as for experienced researchers.
The local diversity and global richness of coral reef fishes, along with the diversity manifested in their morphology, behaviour and ecology, provides fascinating and diverse opportunities for study. Reflecting the very latest research in a broad and ever-growing field, this comprehensive guide is a must-read for anyone interested in the ecology of fishes on coral reefs. Featuring contributions from leaders in the field, the 36 chapters cover the full spectrum of current research. They are presented in five parts, considering coral reef fishes in the context of ecology; patterns and processes; human intervention and impacts; conservation; and past and current debates. Beautifully illustrated in full-colour, this book is designed to summarise and help build upon current knowledge and to facilitate further research. It is an ideal resource for those new to the field as well as for experienced researchers.
Marine Protected Areas (MPAs) are a popular conservation strategy aimed at managing anthropogenic pressures and protecting habitats and the diversity of ocean flora and fauna. Robust, cost-effective sampling of fish assemblages is important in understanding the effects of these management strategies on ocean ecosystems. We compared the sampling effectiveness and efficiencies of three commonly used methods of sampling fish assemblages (underwater visual census (UVC), baited remote underwater stereo-video systems (stereo-BRUVs), and diver operated stereo-video (stereo-DOV) and one emerging method (remotely operated vehicle with stereo-video system (stereo-ROV)). We assessed the assemblage composition, numbers of species and individuals, and the statistical power to detect hypothetical changes in the number of species and individuals for each method.
Stereo-BRUVs sampled a distinctive assemblage compared to all transect-based methods, with more individuals, total species, and predatory fishes from higher trophic groups that are targeted by commercial and recreational fishers. UVC also sampled a distinctive assemblage compared to stereo-ROV and stereo-BRUVs (comparisons with stereo-DOV were not possible due to sampling restrictions). The fish assemblage sampled by UVC consisted of more species and individuals than stereo-ROV and small bodied or cryptic species that were not detected by the video methods. Although stereo-DOV sampled more individuals than stereo-ROV with differences in small schooling species at a few sites, the assemblage composition was broadly comparable. To effectively monitor MPAs a combination of BRUVs, which more effectively sampled fisheries indicator species, and one of the transect based methods should be used. Given the similarities in the assemblages sampled by the stereo-video transect based methods and the advantages associated with health and safety, logistics and field efficiency with remote methods, we recommend stereo-ROV and stereo-BRUVs.
Marine protected areas (MPAs) – clearly defined spaces dedicated to achieving long-term conservation of nature and nature’s values – have been identified as one of the most effective tools for safeguarding marine ecosystems. Other Effective Area-based Conservation Measures (OECMs) are increasingly recognized as an additional tool to achieve global biodiversity goals. As governments refine their conservation targets over the next decade and beyond, it is timely to discuss the role of MPAs and OECMs in meeting global biodiversity and sustainable development goals. Key areas needing improvement to achieve these goals include broader engagement with Indigenous peoples and community groups and increased sustainable financing and management effectiveness. In addition, MPAs and OECMs must be designed and managed to address climate change and include targeted restoration to promote recovery to effectively conserve marine ecosystems and support human needs.
Marine reserves can increase the abundance and size of harvested fish species, but the indirect effects of protection on wider fish assemblages are less well understood. Better understanding how marine reserves indirectly effect reef fish is essential to interpreting changes in non-targeted taxa and informing management expectations as to the long-term effects of marine protection. We investigated how reef fish assemblages and habitats have changed within New Zealand's oldest marine reserve after 40 years of no-take protection (1978 to 2018), and how they differed inside and outside the reserve in 2018. Reef fish assemblages differed between 1978 and 2018, and between reserve and fished sites, and these effects were greatest at depths where habitats had changed. We report an overall increase in fish biomass in the reserve, but a long-term decline in total fish density. The increase in biomass under protection was largely driven by an increase in six target species. Eleven species exhibited long-term declines in the marine reserve; three likely a result of indirect effects related to habitat change and/or increased predation, while other declines likely reflect large-scale changes independent of reserve protection. Predicted indirect effects associated with large-scale habitat change were not apparent, except for an increase in one non-target herbivore species alongside increased kelp abundance. While further work is needed to confirm the mechanisms driving individual indirect effects, the results demonstrate that the long-term indirect effects of protection on reef fish are less common, more complex and more difficult to predict than direct effects.
Consistency in conservation
Marine protected areas (MPAs) are now well established globally as tools for conservation, for enhancing marine biodiversity, and for promoting sustainable fisheries. That said, which regions are labeled as MPAs varies substantially, from those that full protect marine species and prohibit human extraction to those that permit everything from intensive fishing to mining. This inconsistency can in some cases inhibit both conservation and quantifying the proportion of the marine environment that is truly protected. Grorud-Colvert et al . review the consistency of MPAs and propose a framework by which levels of protection can be evaluated and improved. —SNV
Marine fisheries are a critically important source of food, nutrition, and employment for millions of people. As the global population increases, new and expanding pressures are created on fish resources. Marine Protected Areas (MPAs) have been widely promoted as valuable tools for rebuilding or maintaining fish stocks around the world. The success of MPAs, however, widely depends on their particular configuration and management and their effectiveness is often object of contentious debates in both scientific and political arenas. Since fisheries management is a collective action problem, some forms of human cooperation in terms of fishing behaviour can lead to sustainable fisheries and can represent, in theory, a complementary or even an alternative approach to the establishment of no-take marine reserves. We present here a new Agent-Based Model (ABM) that captures the main characteristics of an idealised small-scale fishery. We then use the model to investigate the combined effects of different fishing strategies (expressed by a cooperative trait associated to fishing effort) and various configurations of no-take reserves (including presence or absence of MPA, size of MPA, age of MPA, i.e. time elapsed since its establisment, and distance between two MPAs) on fish abundance and catch under an overfishing regime. Our results show that high cooperation without an MPA can be as effective as lower levels of cooperation combined with an MPA in maintaining fish stocks and catches at relatively high levels. The mobility of our fish agents implies that, contrary to current belief, these results may not be limited to sedentary species. We also found that the greatest impacts on fish abundance and catch are produced by the size of an MPA and the time elapsed since its establishment. Furthermore, the distance between two MPAs has no significant effect, regardless of the cooperation levels characterising the fishing agents. Despite its simplicity, the ABM presented here provides insights on the most plausible effects that combinations of different MPA designs and human cooperation strategies can produce on overexploited small-scale fisheries. When appropriately adapted with a realistic, fishery-specific parameterisation, this model can constitute a valuable tool for evaluating the impact of different resource management strategies. We make the model available as open-source software with the aims of fostering reproducibility, transparency, and flow of ideas.
Non-conventional methods to maintain and restore reef fishery productivity include protecting fishery habitats, hatchery releases, artificial reefs, introduction of exotic species, habitat restoration and marine fishery reserves. I conclude that it is far better to prevent overfishing and stock collapse in the first place than to have to rebuild fishery productivity later. The most important strategies to prevent loss of fishery productivity are switching to less destructive fishing methods, preventing destruction of fishery habitats and protecting some areas by establishment of marine fishery reserves. If fisheries must be rebuilt, habitat restoration and marine reserves appear to be the more promising alternatives over the long term. Except for unique circumstances, deployment of artificial reefs and release of hatchery-raised organisms have less potential for retrieving lost fishery productivity. Because of unpredictable consequences and the general inability to correct mistakes, the introduction of exotic organisms is the least favoured alternative for rebuilding fishery productivity.
The need to compare and combine data quantitatively is becoming more frequent in studies of animal behaviour, ecology and conservation. Using a hypothetical data set, I point out some limitations of combining and comparing data using Null Hypothesis Significance Testing (NHST). First, I discuss three different aspects of data analysis that should regularly be considered: (1) effect size estimation, (2) confidence intervals estimation and, (3) power analysis. I then suggest meta-analysis as a sensible alternative method to account for some limitations of NHST. Meta-analysis is a quantitative technique for the combination and comparison of independent but similar studies. Meta-analysis allows comparison and summary of effect sizes across studies. When testing hypotheses framed in evolutionary theory, where small effects may have profound consequences, a knowledge of the magnitude of the association may be as important as knowing whether the data comply with the arbitrary, sacred and dogmatic significance criterion of p < 0.05.
This study investigates the effects of es-tablishment of the Ras Mohammed Marine Park on fish population structure. The park has been pro-tected from most forms of fishing for 15 years. Ces-sation of fishing is expected to result in increases in abundance and average size of target species and may also lead to shifts in species composition. To determine if such effects were evident, populations of nine commercially fished families and pelagic piscivores were censused using point counts at 15m depth. Effects of protection were determined by comparison of similar sites from three fishing lev-els: (1) none (Ras Mohammed), (2) little-fished, and (3) fished. Data were analysed using ANOVA. The results of the study were complex. Abundance of 1 1 of 45 species differed significantly among fishing levels. There were greater numbers on unfished reefs for four, little-fished for three and fished for four. At the family level, surgeonfishes were signif-icantly more common on fished reefs. Seven species increased in size significantly with decreasing fish-'-ing intensity. Biomass of 14 species differed signif-icantly among fishing levels with higher biomass in unfished sites for five, in fished sites for four and equivocal results for five. At the family level, there were significant differences for parrotfishes and sur-geonfishes with the former greatest on little-fished reefs and the latter on fished. Total biomass of all species combined (excluding the schooling sur-geonfish Naso unicornis) did not differ significantly among fishing levels although mean biomass was 1.2 times greater on unfished than fished reefs. These results provide some support for the view that marine reserve establishment has been effec- tive in protecting stocks. However, fishing levels in the northern Red Sea are low and use of reserves to manage fisheries may prove most effective in regions where fishing intensities are high or use of damaging fishing methods widespread.
Meta-analysis is a statistical technique that allows one to combine the results from multiple studies to glean inferences on the overall importance of various phenomena. This method can prove to be more informative than common ''vote counting,'' in which the number of significant results is compared to the number with nonsignificant results to determine whether the phenomenon of interest is globally important. While the use of meta- analysis is widespread in medicine and the social sciences, only recently has it been applied to ecological questions. We compared the results of parametric confidence limits and ho- mogeneity statistics commonly obtained through meta-analysis to those obtained from re- sampling methods to ascertain the robustness of standard meta-analytic techniques. We found that confidence limits based on bootstrapping methods were wider than standard confidence limits, implying that resampling estimates are more conservative. In addition, we found that significance tests based on homogeneity statistics differed occasionally from results of randomization tests, implying that inferences based solely on chi-square signif- icance tests may lead to erroneous conclusions. We conclude that resampling methods should be incorporated in meta-analysis studies, to ensure proper evaluation of main effects in ecological studies.
A frequent expectation of the use of marine reserves in management of coral reef fisheries is maintenance or enhancement of yields to areas adjacent to reserves by adult (post-settlement) movements from reserve to fished areas (the so-called 'spillover effect'). Demonstration of this effect has been rare. This paper reports on some circumstantial evidence derived from underwater visual census monitoring of densities of large predatory coral reef fish [Serranidae (Epinephelinae), Lutjanidae, Lethrinidae and Carangidae as a group] inside and adjacent to a small marine reserve at Apo Island in the central Philippines over a 10 yr period (1983 to 1993). The marine reserve (sanctuary) at Apo Island was established in 1982 and was protected from fishing for the duration of the study. The non-reserve area was open to fishing by up to 200 municipal fishers using traditional fishing gear (bamboo traps, hooks and lines, gill nets and spears). Significant positive correlations of both mean density and species richness of large predatory fish with duration of reserve protection (from 1 to 11 yr) were observed in both the reserve and non-reserve areas surveyed. The minimum distance from the boundary of the reserve to the non-reserve area surveyed was 200 m. During the first 8 yr of reserve protection combined, the density of large predatory fish at distances 200 to 300, 300 to 400 and 400 to 500 m from the reserve boundary did not differ significantly from an even distribution (chi-squared test, p > 0.05). During the period of 9 to 11 yr of protection combined, there was a significantly higher density of these fish in the area closest to the reserve (i.e. in the 200 to 300 m area, chi-squared test, p < 0.05). This visual census data is consistent with a proposed model of adult fish export from the reserve to the non-reserve areas. Along with interview data collected in 1986 and 1992 that showed that fishers were unanimous that their yields had increased since the reserve was implemented, this study provides evidence for export of adult fish from reserve to fished areas.
Fishers have been complaining about the effects of bottom trawl gear on the marine environment since at least the 14th century. Trawl gear affects the environment in both direct and indirect ways. Direct effects include scraping and ploughing of the substrate, sediment resuspension, destruction of benthos, and dumping of processing waste. Indirect effects include post‐fishing mortality and long‐term trawl‐induced changes to the benthos. There are few conclusive studies linking trawling to observed environmental changes since it is difficult to isolate the cause. However, permanent faunal changes brought about by trawling have been recorded. Research has established that the degree of environmental perturbation from bottom trawling activities is related to the weight of the gear on the seabed, the towing speed, the nature of the bottom sediments, and the strength of the tides and currents. The greater the frequency of gear impact on an area, the greater the likelihood of permanent change. In deeper water where the fauna is less adapted to changes in sediment regimes and disturbance from storm events, the effects of gear take longer to disappear. Studies indicate that in deep water (>1000 m), the recovery time is probably measured in decades.
Potential changes in spawning stock biomass per recruit and yield per recruit, when varying fractions of exploitable reef area were closed to fishing, were estimated. Fundamental transfer rates were adjusted for possible density-dependent emigration from closed areas as relative densities decreased in surrounding non-closed areas because of continued fishing. Three hypothetical "fish-types' were constructed, bracketing the likely extremes in fundamental transfer rates and related life-history parameters of Pacific coral reef fishes: a small-bodied, fast-growing and short-lived, strongly philopatric species of damselfish was contrasted with a large-bodied, relatively slow-growing, long-lived, vagile species of jack. A "surgeonfish' type was used to represent intermediate parameter values. -from Author
We studied the coral-reef fish communities of Saba Marine Park (Netherlands Antilles) and Hol Chan Marine Reserve (Ambergris Caye, Belize) in the Caribbean to assess differences between them and adjacent ecologically similar sites after 4 yr of protection from fishing. Forty-five percent of target species commonly recorded in visual censuses in Belize (23 % of all recorded target species), and 59 % at Saba (22 %), showed greater abundance, size or biomass in shallow protected sites. These differences are considered primarily to reflect increased survivorship with the cessation of fishing mortality. The greatest estimated biomasses were observed in locally protected snapper (Lutjanidae) in Belize and Saba, and grunt (Haemulidae) at Saba. In both protected areas the local stock of visible demersal target fishes was 1.9 to 2.0 times greater in biomass and 2.2 to 3.5 times greater in commercial value than in fished sites. Larger local stock of many target species is likely to support higher egg output from the protected areas, while larger predator biomass will mean more intense predation at the protected sites.
The movements, growth rates and distribution of a population of white goatfish Mulloides flavolineatus were investigated using a combination of tag-and-release and sonic tracking techniques. The study site was a 137 km2 patch reef which has been a no-fishing conservation zone for over 30 years. The population showed high site fidelity; 93% of recaptures occurred at the release site, with times at liberty of up to 531 days. Tracking revealed crepuscular movements away from daytime schooling sites to consistent nighttime foraging grounds up to 600 m away. The route taken between daytime and nighttime habitats was the same each night. Suround-net quadrats were used to measure goatfish densities on the nighttime feeding grounds. The high site fidelity and limited range of diel movements of these fish indicate that quite small harvest refugia can serve to effectively protect populations of mature adults, and that for most of the year, emigration of adults into adjacent fisheries was minimal.
Ludwig (1995) argued that (1) management for sustained yield cannot be optimal and (2) effective management models cannot be realistic. I concur, and I begin with the view that sustained yield is more important than maximum yield; indeed maximum sustained yield must become a constraint rather than a target. Mangel et al. (1996) stress that we are very far from managing ecosystems; we manage human interventions in ecosystems. Following Ludwig's advice, I will use a relatively simple model to show how essential fish habitat and fishing mortality are intimately connected—loss of spawning habitat is equivalent to additional fishing mortality on adults. Reserves can help guarantee sustainability of the fishery, even when fishing mortality outside the reserve cannot be very well controlled (despite attempts to do so). In fact, in some circumstances (identified by the model) reserves can simultaneously enhance the stock, protect habitat, and increase catch. Finally, I will show how the model can be used to help resolve the reserve design question, which in this case is how we decide how much spawning habitat and how much of the fishing ground to protect.
By comparing stations inside and outside the total protection area of the reserve (where all fishing is prohibited) one could assess the ecological effects of protection. Mean density and biomass were similar for the different Posidonia oceanica meadow stations: 3 ind./10 m2 (0-25 m), 56-66 g ww/10 m2 (0-10 m) and 35 g ww/10 m2 (10-25 m), but demographic structure and relative importance of dominant species differed between the total protection area and partly protected areas of the reserve. On rocky substrate, density and biomass differed significantly: 0.6 vs 0.1 ind./10 m2 and 202 vs 42 g ww/10 m2 for totally and partly protected areas, respectively. -from Author
Marine reserves, where fishing is excluded, have been argued to be an effective means of managing complex reef fisheries and of protecting populations of species vulnerable to overfishing. The argument rests on predictions of increases in abundance and size of fishes after the elimination of fishing mortality, which in turn leads to greater egg production per unit of reef and greater export via pelagic dispersal to fishing grounds. This study reports responses of fish populations to area closure in a small Caribbean marine reserve surrounding the island of Saba in the Netherlands Antilles. Part of the reserve has been closed to fishing since 1987, and the remainder is subject only to light fishing. Fish populations were visually censused and sizes of individuals present estimated from counts in fished and unfished areas of the marine park in 1991 and 1993. For four of five commercially fished families, biomass was greater in the unfished area than in the fished. Predictions of greater abundance and size in the unfished area were upheld for many of the species observed. Between 1991 and 1993 overall biomass of commercially important families increased 60%, based largely on increases in abundance between years. The predatory snappers (Lutjanidae) increased 220%. Fishing pressure in Saba was reduced between censuses due to changing employment opportunities. It was notable that populations increased in both fished and unfish ed areas of the park, and the latter is probably an effect of this reduced fishing intensity. Reserves have been suggested as refuges for species vulnerable to overexploitation, especially groupers. Despite protection from fishing, the Saba Marine Park has low population densities of such species, perhaps due to a lack of supply of larvae from unprotected source areas. My study shows that target fish populations may respond swiftly to reductions in fishing pressure and that reserves could play an important role in fisheries management. But protection of vulnerable species is only likely to be successful if networks of reserves are established throughout species ranges to link larval supply and settlement areas.
Las reservas marinas, donde la pesca esta excluída, han sido consideradas como un medio efectivo para manejar las complejas pesquerias de arrecifes y para proteger poblaciones de especies vulnerables a la sobrepesca. El argumento se basa en las predicciones de un incremento en la abundancia y tamaño de los peces luego de la remoción de la mortalidad por pesca, lo que a su vez conduce a una mayor producción de huevos por unidad de arrecife y a una mayor exportación por medio de la dispersión pelágica a las áreas de pesca. Este estudio reporta las respuestas de las poblaciones de peces a la clausura de un área en una pequeña reserva marina del Caribe que rodea la isla de Saba en las Antillas Holandesas. Parte de la reserva ha estado cerreda a la pesca desde 1987 y et resto ha estado sujeto solo a una pesca reducida. Las poblaciones de peces fueron sensadas visualmente y el tamaño de los individuos presentes estimados a partir de conteos en las áreas pescadas y no pescadas del parque marino en 1991 y 1993. La biomasa para cuatro de las cinco familias sujetas a la pesca comercial fue mayor en el área cerrada a la pesca que en aquella sujeta a la misma. Las predicciones de una mayor abundancia y tamaño en el área libre de pesca fue apoyada para muchas de las especies observadas. Entre 1991 y 1993 la biomasa total de las familias comercialmente importantes incrementó un 60%, debido principalmente a aumentos en abundancia entre los distintos años. Los pargos predadores (Lutjanidae) aumentaron un 220%. La presión pesquera en Saba fue reducida entre los censos debido al cambio de oportunidades de empleo. Fue notable que las poblaciones aumentasen tanto en las áreas pescadas como en aquellas no pescadas del parque, el incremento en las áreas sujetas a la pesca es probablemente el efecto de esta redución de la presión pesquera. Las reservas han sido propuestas como refugios para las especies vulnerables a la sobreexplotación, en especial para las chernas. A pesar de estar protegido de la pesca, el Parque Marino de Saba tiene bajas densidades poblacionales de estas especies, quizás debido a una falta de suministro de larvas de áreas “fuentes” no protegidas. Este estudio demuestra que las poblaciones de peces sujetas a la pesca responderían rapidamente a reducciones en la presión pesquera y que las reservas podrían jugar un papel importante en el manejo pesquero. Sin embargo, la protección de especies vulnerables sálo sería exitosa si se establecen redes de reservas a lo largo de todó el área de distribución de las especies a los efecto de conectar las áreas de provisión de larvas y las áreas de asentamiento.
Meta-analysis provides formal statistical techniques for summarizing the results of independent experiments and is increasingly being used in ecology. The response ratio (the ratio of mean outcome in the experimental group to that in the control group) and closely related measures of proportionate change are often used as measures of effect magnitude in ecology. Using these metrics for meta-analysis requires knowledge of their statistical properties, but these have not been previously derived. The authors give the approximate sampling distribution of the log response ratio, discuss why it is a particularly useful metric for many applications in ecology, and demonstrate how to use it in meta-analysis. The meta-analysis of response-ratio data is illustrated using experimental data on the effects of increased atmospheric CO{sub 2} on plant biomass responses.
We synthesize the results of empirical studies of marine reserves to assess the potential benefits of protection for fish populations. Our meta-analyses demonstrate that the overall abundance of fishes inside reserves is, on average, 3.7 times higher than outside reserve boundaries. This enhancement is mainly a result of a significant increase in abundance of species that are the target of fisheries. Non-target species are equally abundant inside and outside reserves. Large-bodied species also respond more to protection, irrespective of their fishery status. Species within genera show great heterogeneity in their response to protection despite similarities in their life histories. Our study confirms that marine reserves benefit fish populations and highlights the need for monitoring prior to reserve establishment to provide more accurate, habitat- controlled studies of the effects of marine reserves on fish populations.
A fishery independent underwater visual census technique was used to assess the effects of fishing on the diversity, biomass and trophic structure of the diurnally active non-cryptic reef- associated fish communities of the Seychelles. One hundred and thirty four species associated with three significantly different types of reef habitat were censused at one unfished ground and in six fishing grounds subject to different fishing intensities. There was an inverse relationship between fishing intensity and the biomass of several species targeted by the fishery. The diversity of families containing target species (lutjanidae, lethrinidae) was significantly higher at unfished and lightly fished sites as was the total biomass of the fish community and the biomass of piscivorous, piscivorous/invertebrate feeding and herbivorous trophic groups. However, there was no indication that the biomass of non-target species increased in response to the removal of their predators by fishing. The findings of this study are significant for fishery managers because they suggest that the intensive differential cropping of top predators will not necessarily lead to increases in the biomass and productivity of their prey.
We evaluate the goals of meta-analysis, critique its recent application in ecology, and highlight an approach that more explicitly links meta-analysis and ecological theory. One goal of meta-analysis is testing null hypotheses of no response to experimental manipulations. Many ecologists, however, are more interested in quantitatively measuring processes and examining their systematic variation across systems and conditions. This latter goal requires a suite of diverse, ecologically based metrics of effect size, with each appropriately matched to an ecological question of interest. By specifying ecological mod- els, we can develop metrics of effect size that quantify the underlying process or response of interest and are insensitive to extraneous factors irrelevant to the focal question. A model will also help to delineate the set of studies that fit the question addressed by the meta- analysis. We discuss factors that can give rise to heterogeneity in effect sizes (e.g., due to differences in experimental protocol, parameter values, or the structure of the models that describe system dynamics) and illustrate this variation using some simple models of plant competition. Variation in time scale will be one of the most common factors affecting a meta-analysis, by introducing heterogeneity in effect sizes. Different metrics will apply to different time scales, and time-series data will be vital in evaluating the appropriateness of different metrics to different collections of studies. We then illustrate the application of ecological models, and associated metrics of effect size, in meta-analysis by discussing and/or synthesizing data on species interactions, mutual interference between consumers, and individual physiology. We also examine the use of metrics when no single, specific model applies to the synthesized studies. These examples illustrate that the diversity of ecological questions demands a diversity of ecologically meaningful metrics of effect size. The successful application of meta-analysis in ecology will benefit by clear and explicit linkages among ecological theory, the questions being addressed, and the metrics used to summarize the available information.
This study investigates the effects of establishment of a marine reserve on the coral reef fish communities at Mayotte Island, Western Indian Ocean, after three years of protection. Both total species richness and global abundance did not differ significantly between protected and non-protected areas. Nevertheless, there were significant differences for numerous families and species. Most of the big carnivorous fishes (Serranidae, Lutjanidae, Lethrinidae) were more diverse and more abundant in the marine reserve. Conversely, other fishes, mainly in the families Pomacentridae, Scaridae and Acanthuridae, presented the opposite pattern. The mean biomass of commercial fish species was significantly higher in the reserve (202 g.m-2) than in non-protected areas (79 g.m-2). This pattern was also evident for carnivorous fishes, such as Epinephelus microdon, and semi-pelagic fishes, such as Caesionidae. In contrast, other commercial species, such as Scarus caudovittatus and Acanthurus nigricauda had higher biomass in non-protected areas. Despite this apparent contradiction, our results seem to be linked with the marine reserve protection. Cessation of fishing activities in the reserve may have caused increases in diversity, abundance and biomass of large carnivores. The decrease in the number of these fishes in non-protected areas due to fishing may favour development of other populations, dominated by potential prey for carnivorous fishes.
(1) A visual scuba diving census, in which abundance and size class structure of conspicuous fish species were determined, was used to assess the effects of depth and marine reserve fishing restrictions on the structure of a Mediterranean rocky reef fish assemblage by comparing communities at sites from two depth ranges inside and outside a marine reserve. (2) The total assemblage had thirty-five conspicuous species and was dominated by Labridae (thirteen spp.) and Sparidae (nine spp.). (3) Mean species richness (number of species) and diversity (Shannon) did not differ significantly between sites. (4) Ordination of abundance data showed that occurrence and relative abundance of species was affected by depth (deep samples separated completely from shallow samples) and marine reserve status (samples from the marine reserve were significantly separated from those taken at the same depth outside the reserve). (5) Samples from the same depth were similar, because the majority of species showed a preference for either deep or shallow areas. The known biology of several species indicated that feeding requirements may be responsible for depth preferences. (6) Samples from reserve sites had signficantly higher densities of fish species sought after and/or vulnerable to local fishing methods, than those from non-reserve sites of similar depth. (7) Size frequency distributions of vulnerable species at reserve sites generally had a larger modal size class than distributions from non-reserve sites. (8) The data suggest that reduced fishing pressure in the reserve has provided effective protection for species vulnerable to fishing.
Reductions in fishing mortality within no-take coral reef marine reserves can produce gradients in the density and size of fishes across reserve boundaries. Such gradients may be affected by other factors, however, including differences in habitat quality between reserve and non-reserve areas and the movement of fish across reserve boundaries. To examine the effects of protection from fishing mortality and of habitat quality on an assemblage of exploited reef fishes, we measured the spatial patterns of fish density and size on fringing reefs near the boundary of the Barbados Marine Reserve (Barbados, West Indies) and statistically controlled for habitat correlates of fish density and size. Reserve sites supported a higher total density and size of fishes than non-reserve sites. Most species had a non-significantly higher mean density and size at reserve sites. The density and/or size of many species were correlated with the depth, rugosity, and/or substrate composition of sites. After statistically controlling for the effects of habitat correlates, the difference in total density between reserve and non-reserve sites remained significant, and the mean density and size of most species remained nonsignificantly higher at reserve sites. Neither the mobility of species nor their vulnerability to capture by Antillean fish traps was correlated with their relative difference in density or size between reserve and non-reserve sites. Spearfishing target species had a significantly higher relative difference in size between reserve and non-reserve sites than non-target species. Protection from fishing mortality and higher habitat quality appear to contribute to the increased density and size of fishes on study reefs in the Barbados Marine Reserve, and this difference is not compromised by emigration from the reserve.
High population densities of larger fish within reserves could result in emigration of fish to surrounding non-reserve areas, producing a gradient of abundance and mean size across the reserve boundaries. The difference in fish abundance and size between reserve and non-reserve should be higher for sedentary than for mobile species and for highly catchable than for less catchable species. To test these hypotheses we estimated the abundance and size of fishes by trapping and visual census on fringing reefs in Barbados: 5 reefs within the 2.2 km of the Barbados Marine Reserve (BMR) and 8 reefs in the non-reserve (NR) area within 4 km of the reserve boundaries. The abundance of large, trappable size fish of all species combined was higher in the BMR than in the NR, but abundance of small, nontrappable fish did not differ between BMR and NR. Trap catches decreased gradually with distance from the BMR center, but this gradient of abundance was less evident in visual census counts of trappable size fishes of all species combined, and not apparent in trap or visual census estimates of abundance for individual species. Mean size was larger in the BMR than in the NR for 18 out of 24 species. The relative differences in both abundance and size between BMR and NR did not differ between mobile and sedentary fish taxa. However, for sedentary taxa, the relative differences in abundance and size increased with trappability (the vulnerability to traps, which are the most common fishing method). These patterns suggest that the BMR does protect the fish community from fishing mortality and that emigration rates are generally low. Trappability and mobility depend on complex behavioral characteristics of fishes and are potentially important for the functioning of marine reserves.
Recruitment rates are determined by larval production, and both intrinsic (eg reproductive mode, larval behavior) and extrinsic (eg predation, resource availability, currents) factors that influence the geographic range over which a refuge can effectively supply recruits. The size, number, and distribution of refuges depend on patterns of larval replenishment. Since resource requirements of fish often change with ontogeny and reproductive condition, refuges may need to include a wide variety of habitats. Larval production by refuges may be enhanced by multispecies management that provides protection for or allows harvesting of nontarget species. Additionally, protection may be needed for resources located outside refuges that enhance recruitment to harvested populations. -from Authors
Marine fisheries refugia, unaltered areas that serve as sources of replenishment, can potentially compensate for recruitment and ecosystem overfishing and enhance fishery yields for some coastal stocks. Evidence from existing marine reserves indicates that increased abundance, individual size, reproductive output, and species diversity occurred in a variety of marine species in refuges of various sizes, shapes, and histories in communities ranging from coral reefs to temperate kelp forests. Fishery yield enhancement in areas surrounding refuges occurred in the few studies where yields were examined. The export of propagules required to enhance fisheries in areas surrounding refugia adds a level of complexity to the design of fishery refugia beyond that of terrestrial reserves. Fishery refugia design should consider species life histories, oceanographic regimes, habitat quality, and socioeconomic factors. -from Authors
This manual shows you a statistical program that will allow you to summarize the results of multiple independent studies using either a fixed-effects model or mixed-effects model meta-analysis, and allow you to compare multiple classes using cumulative effect sizes and confidence intervals, as well as the between-class homogeneity, Q
B. The program also tests within-class homogeneity, Q
W, in the fixed-effects model, using chi-square. The program also allows for the direct input of an effect size by the user and the sampling variance of that effect size, for each study. This input allows the user to perform a meta-analysis on alternative measures of effect size (e.g., correlation coefficient, odds ratio, and so on).
This program will also allow you to incorporate resampling tests into your meta-analysis. In particular, confidence intervals for mean effect sizes can be generated using 2 different bootstrap procedures (bootstrap confidence intervals and bias-corrected bootstrap confidence intervals).
The program also allows you to refine your analysis by removing certain classes or studies from the analysis without having to alter the data file. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
In 1896, Sir Almroth Wright—a colleague and mentor of Sir Alexander Heming, who discovered penicillin—developed a vaccine to protect against typhoid (Susser 1977; see Roberts 1989). The typhoid vaccine was tested in several settings, and on the basis of these tests the vaccine was recommended for routine use in the British army for soldiers at risk for the disease. In that same year, Karl Pearson, the famous biometrician, was asked to examine the empirical evidence bearing on the decision. To do so, he synthesized evidence from five studies reporting data about the relationship between inoculation status and typhoid immunity, and six studies reporting data on inoculation status and fatality among those who contracted the disease. These eleven studies used data from seven independent samples, with four of those being used twice,once in a synthesis of evidence about incidence of typhoid among those inoculated, and once in a synthesis of evidence about death among those contracting typhoid. He computed tetrachoric correlations for each of these eleven cases, and then averaged these correlations (separately for incidence and fatality) to describe average inoculation effectiveness. In his subsequent report of this research, Karl Pearson concluded that the average correlations were too low to warrant adopting the vaccine,since other accepted vaccines at that time routinely produced correlations at or above .20 to .30: "I think the right conclusion to draw would be not that it was desirable to inoculate the whole army, but that improvement of the serum and method of dosing, with a view to a far higher correlation, should be attempted" (1904b, 1245). We tell this story for three reasons. First, we discovered this example when first researching this chapter in 1991,and at the time it was the earliest example of what we would now call a meta-analysis. So it is historically interesting,although a few older examples have now been located.Second, we will use the data in table 14.1 to illustrate how to combine results from fourfold tables. Finally,the study illustrates some conceptual and methodological issues involved in combining estimates of effect size across studies, points we return to in the conclusion of this chapter. In many ways, the capacity to combine results across studies is the defining feature of meta-analysis, so the conceptual and statistical issues involved in computing these combined estimates need careful attention. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The role of a marine protected area in enhancing local fisheries, through the emigration or spillover or exploitable fishes, was studied in a coral reef park (Mombasa Marine Park, Kenya) and fishery over a seven year period during a time when the park's border changed and pull seines were eliminated. We measured catches before and after the park's establishment and during the management changes and compared these catches with the unmanaged side of the park. Additionally, we placed baited traps on both sides of the park over a full tidal cycle which allowed us to measure the spillover from the park compared to the deeper rougher and less fished reef edge. The total wet mass of catches per trap declined as a function of the distance away from the park edge on both the southern and northern sides. However, this relationship was truncated on the unmanaged side, which also had smaller catches, smaller fish and fewer species than the managed side. Trap fishers on the managed side adapted to the spillover by increasing the traps per fisher, which had the effect of reducing the catch per trap. Tides and reef morphology also appeared to interact and influence catches, but we found no relationship between catches and benthic substratum cover, which was usually dominated by sea grass and sand. Spillover form the deeper reef edge was evident for the managed but not the unmanaged side of the park, but may be due to the differences in reef morphology interacting with tidal patterns rather than management. On the managed side, the park significantly increased the catch per fisher and catch per area by 50% but even after the park size was reduced, the total catch was reduced by ~30%. The reduced park was still ~50% of the total area. Consequently the catch per area increase was insufficient to compensate for the lost area over this early period of the park's establishment. Spillover was greatest for the dominant fisheries species. There were moderately vagile species including Signaidae, Lethrinidae, and Acanthuridae families which had instantaneous emigration rates from the park to the reserve fishing ground of ~0.5. Our field survey combined with previous modeling studies, based on adult emigration rates from marine reserves, suggests that tropical fisheries dominated by rabbitfish, emperors and surgeonfish should be enhances by closed areas of ~10-15% of total area. The optimal protected area may increase if larval export is important, but the predicted response should not be measurable for >10 years, beyond the length of our study as breeding stock develop inside protected areas.
IntroductionWhat Happens to Target Species in Mpas?What are the Potential Benefits to Fishers?What else do MPAs Offer?Realities, Advocacy and Implementation of MpasConclusions
AcknowledgementsReferences
Abstract Establishing permanent ‘no-take’ marine reserves, areas where fishing and all other extractive activities are prohibited, is an attractive but under-utilized tool for fisheries management. Marine reserves could potentially deal with many fishery problems that are not effectively addressed by other traditional management measures; they also offer numerous social, economic, and scientific benefits not directly related to fisheries. Limited but growing research has shown beneficial biological and economic effects of marine reserves on fisheries. More research is needed, especially at larger scales, to determine the ideal marine reserve size, number and location necessary to optimize fisheries productivity and resource conservation. Sufficient evidence is available to justify the expanded use of marine reserves in an adaptive approach to fisheries management.
This paper summarizes research on the uses of marine reserves for fisheries management. Examples emphasize temperate marine reserves.
Marine reserves commonly support higher densities and larger sizes of heavily fished species than are found outside reserves.
‘Spillover’ of individuals across reserve borders is likely to augment local catches. There are good reasons to expect such spillover, and there is limited direct evidence for it. However, the magnitude of any resulting increase in local catches will be difficult to predict.
‘Larval export’ from reserves has potential to augment recruitment over large regions, but its success will depend upon many factors that are difficult to predict. No studies have clearly tested the effects of larval export.
To design more effective marine reserves, studies are needed of the movement patterns and habitat requirements of all life stages (larval, settlement, juvenile, adult, feeding, and breeding) of targeted species.
To determine clearly the effects of marine reserves on fisheries requires replicated before/after studies.
Population density, number of species, diversity, and species-area relationships of fish species in eight common coral reef-associated families were studied in three marine parks receiving total protection from fishing, four sites with unregulated fishing, and one reef which recently received protection from fishing (referred to as a transition reef). Data on coral cover, reef topographic complexity, and sea urchin abundance were collected and correlated with fish abundance and species richness. The most striking result of this survey is a consistent and large reduction in the population density and species richness of 5 families (surgeonfish, triggerfish, butterflyfish, angelfish, and parrotfish). Poor recovery of parrotfish in the transition reef, relative to other fish families, is interpreted as evidence for competitive exclusion of parrotfish by sea urchins. Reef substrate complexity is significantly associated with fish abundance and diversity, but data suggest different responses for protected versus fished reefs, protected reefs having higher species richness and numbers of individuals than unprotected reefs for the same reef complexity. Sea urchin abundance is negatively associated with numbers of fish and fish species but the interrelationship between sea urchins, substrate complexity, coral cover, and management make it difficult to attribute a set percent of variance to each factor-although fishing versus no fishing appears to be the strongest variable in predicting numbers of individuals and species of fish, and their community similarity. Localized species extirpation is evident for many species on fished reefs (for the sampled area of 1.0 ha). Fifty-two of 110 species found on protected reefs were not found on unprotected reefs.
This study examined the effect of fishing on the density, biomass, species richness and overall structure of the reef fish
community at two islands (Sumilon and Apo) in the Philippines from 1983 to 1993. A series of natural fishing experiments over
this period involving marine reserves were monitored at each island, where estimates of fishing intensity and selectivity
were available. Fishing intensity (15% and 25% of biomass removed per year at Sumilon and Apo, respectively) was high enough
to affect total community biomass, but not density, significantly. Species richness was not affected significantly by fishing,
except at Sumilon reserve. The fishery was relatively non-selective with most families/trophic groups caught roughly in proportion
to their contribution to community biomass. Thus fishing did not alter the relative abundance of the major families/trophic
groups significantly, except during a period of use of explosives and drive nets in the Sumilon reserve. At the level of family/trophic
group the community displayed strong resilience of structure. There was little evidence of secondary effects e.g. declines
in abundance of large predators resulting in measurable increases in abundance of their prey. This resilience of the community
to the effects of fishing most likely results from three important community attributes (open nature of the component populations,
likely maintenance of upstream recruitment supply and apparent lack of any obvious “keystone” species or families) and one
important characteristic of the fishery (relatively non-selective with respect to the components of the community).
The macrobenthic (coral, algae, and sea urchins) and fish communities in 15 back-reef sites on the patch and rock-island reefs of southern Kenya and northern Tanzania (∼250 km of coastline) were studied in order to (1) test an overfishing model developed in Kenya’s fringing reef (McClanahan, 1995a, A coral reef ecosystem-fisheries model: impacts of fishing intensity and catch selection on reef structure and processes. Ecol. Model. 80, 1–19.), (2) develop a baseline of information on Tanzanian coral reef ecosystems, and (3) determine if some of the government gazetted but unprotected marine reserves were still deserving of protective management. The overfishing model was tested by comparing five sites in two fully protected reefs—one in southern Kenya (Kisite Marine National Park) and the other in Zanzibar (Chumbe Island Coral Park)—with 10 sites in eight fished reefs, and by comparing coral surveys conducted in reefs off of Dar es Salaam in 1974 with present-day studies. These comparisons suggest that fishing is primarily reducing the abundance of angelfish, butterflyfish, parrotfish, scavengers, surgeonfish, and triggerfish groups while some species of small-bodied damselfish and wrasse appear to have benefited. The total fish wet weight estimate was 3.5 times higher in protected than unprotected sites. Sea urchin abundance was six times higher, and predation rates on tethered sea urchin Echinometra mathaei were two times lower, in unprotected compared to protected sites. This is largely attributable to the reduction of the red-lined triggerfish Balistapus undulatus and other sea urchin predators by fishing. Loss of coral cover and changes in coral generic composition had occurred in four of the five sites visited in the Dar es Salaam area after the 22-year period. There was no evidence for species losses. One site appeared to be severely damaged over this time. Some reefs were dominated by fleshy brown algae, such as Sargassum and Dictyota, which may result from a loss of grazers and coral cover. Reduced fishing effort, elimination of destructive gear (dynamite and beach seines), protection of vulnerable species and, in some cases, sea urchin reductions could rectify the problems of overfishing. Despite the damage, the gazetted but unprotected reefs of Mbudya and Bongoyo still have high potential as marine protected areas due to the persistence of species and reef structure.
While marine reserves can replenish local populations of reef fishes exploited by fishermen through enhanced survivorship of post-recruitment fishes, the manner in which reserves enhance larger-scale recruitment to fish stocks is poorly understood. We investigate a metapopulation model to see how marine reserves might help to conserve such populations and benefit fisheries. The model defines two kinds of patches: (i) those open to fishing and (ii) those maintained as reserves free from exploitation. Each patch may occur in one of two states according to whether or not it contains fishes recruited to the fishery. It is shown that reserves become highly beneficial as the local extinction rate caused by fishing becomes large because they provide a source of recruitment into fished-out patches. In such circumstances, the introduction of reserves meets the needs both of conservation and of sustainable exploitation of the fishery.The abundance of the exploitable population is maximized when half of all patches (reserves + exploited patches) are occupied by the stock. The sustainable yield is also maximized when half of all patches are occupied, assuming that yield is proportional to the local extinction rate. This result could provide a rule of thumb for fishery managers addressing the specific question of enhancing recruitment in heavily deleted stocks of certain reef fisheries. However, like other metapopulation models, the one here makes some important simplifying assumptions which would need to be addressed in the application of these results to specific fisheries.
The reef biota in four Tasmanian marine reserves and at associated unprotected reference sites was investigated over a 6-year period following protection from fishing. The largest reserve at Maria Island (7 km coastline length) proved the most effective at achieving species conservation and resource enhancement. The number of fish, invertebrate and algal species, the densities of large fishes (>325 mm length), bastard trumpeter (Latridopsis forsteri) and rock lobsters (Jasus edwardsii), and the mean size of blue-throated wrasse (Notolabrus tetricus) and abalone (Haliotis rubra), all increased significantly within the Maria Island reserve relative to external reference sites. Increases of an order of magnitude in the biomass of rock lobsters and two orders of magnitude in the abundance of trumpeter were particularly noticeable. Small abalone declined in density within the reserve, while large abalone became more numerous. The effectiveness of marine reserves corresponded with reserve size. Changes in species richness of fishes, invertebrates or plants were not detected in any of the three smaller reserves, other than an increase in number of fish species greater than 325 mm size within the Tinderbox marine reserve (2 km reserve length). Although patterns were partly obscured by the low power of statistical tests, trends were generally evident at the Tinderbox reserve for increasing densities of large fishes and rock lobsters, and for increases in the mean size of rock lobsters, abalone and blue-throated wrasse. Most of these trends were not apparent in the reserves with small reef areas at Governor Island (1 km reserve length) and Ninepin Point (1 km length). Rock lobsters above the legal size limit nevertheless became abundant in all reserves by the end of the study while remaining rare outside. Indirect changes to reef assemblages were also detected following the declaration of the Maria Island marine reserve. Accompanying the increase in macroalgal species richness was a change in predominant plant species from Cystophora retroflexa to Ecklonia radiata. Results of this study provide the first clear evidence that shallow Tasmanian reef ecosystems are overfished, and that unfished coastal ecosystems differ substantially from those where fishing occurs. The most noticeable changes caused by fishing were the virtual elimination of net-susceptible and heavily targeted species, which may otherwise be common, plus indirect changes to algal communities. We suggest that ecosystem change associated with fishing of shallow coastal reefs may be a widespread phenomenon worldwide.
Statistics is a subject of many uses and surprisingly few effective practitioners. The traditional road to statistical knowledge is blocked, for most, by a formidable wall of mathematics. The approach in An Introduction to the Bootstrap avoids that wall. It arms scientists and engineers, as well as statisticians, with the computational techniques they need to analyze and understand complicated data sets.
Quantitative synthesis across studies requires consistent measures of effect size among studies. In community ecology, these measures of effect size will often be some measure of the strength of interactions between taxa. However, indices of interaction strength vary greatly among both theoretical and empirical studies, and the connection between hypotheses about interaction strength and the metrics that are used to test these hypotheses are often not explicit. We describe criteria for choosing appropriate metrics and methods for comparing them among studies at three stages of designing a meta-analysis to test hypotheses about variation in interaction intensity: (1) the choice of response variable; (2) how effect size is calculated using the response in two treatments; and (3) whether there is a consistent quantitative effect across all taxa and systems studied or only qualitatively similar effects within each taxon-system combination. The consequences of different choices at each of these stages are illustrated with a meta-analysis to examine the relationship between competition/facilitation intensity and productivity in plants. The analysis used a database of 296 cases in 14 studies. The results were unexpected and largely inconsistent with existing theory: competition intensity often significantly declined (rather than increased) with productivity, and facilitation was sometimes restricted to more productive (rather than less productive) sites. However, there was considerable variation in the pattern among response variables and measures of effect size. For example, on average, competitive effects on final biomass and survival decreased with standing crop, but competitive effects on growth rate did not. On the other hand, facilitative interactions were more common at low standing crop for final biomass and growth rate, but more common at high standing crop for survival. Results were more likely to be significant using the log response ratio (In[removal/control]) as the effect size than using the relative competition intensity ([removal - control]/removal), although the trends for these conceptually similar indices did not differ. When all studies were grouped in a single meta-regression of interaction intensity on standing crop to test quantitative similarity among studies, survival showed the dearest negative relationship. However, when the same regressions were done for each unique combination of taxon and site within each study to test for qualitative similarity among studies, the slopes averaged over studies tended to be negative for biomass and growth rate, but not different from zero for survival. These results are subject to a number of caveats because of the limitations of the available data-most notably, the extension of effects of interactions on individual growth or survival to effects on population distribution and abundance or community structure is highly problematic. Nevertheless, the fact that none of the meta-analyses demonstrated a significant positive relationship between competition and standing crop but that we frequently found negative relationships is an important pattern that has not been apparent from qualitative surveys of individual studies, and it demonstrates the potential power of meta-analysis in ecology. We conclude with recommendations to overcome some of the limitations of the currently available data and meta-analytical procedures.
Managing most marine finfisheries to achieve optimum yields is an unattainable dream. Protecting these resources from serious depletion through precautionary management seems the only practical option. But even this is of limited application if we demand scientific data for each managed fishery. There are too few researchers to do the work and, in any event, such research would usually not be cost-effective. Thus, we need not merely precautionary management; we need data-less management.