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Successful parks for sharks: No-take marine reserve provides conservation benefits to endemic and threatened sharks off South Africa
Abstract
Sharks are among the most threatened vertebrates on the planet. Marine protected areas (MPAs) have been widely established and promoted as a shark conservation tool. However, the geographic ranges of most imperiled shark species (endemic and threatened) fall outside the current global networks of MPAs, leaving the protective benefits of this tool questionable for the shark species of highest conservation concern. The Western Cape of South Africa is a hotspot for endemic and threatened shark species. Here, we examined the potential protective benefit of a no-take marine reserve (the De Hoop MPA) for imperiled shark species using baited remote underwater video stations (BRUVS). Eleven shark species were documented, with six of 11 species (55%) classified as threatened with extinction by the International Union for the Conservation of Nature. The composition of the shark assemblage was dominated by small to mid-sized species, including small endemics. Species-specific habitat preferences were identified, with all these habitats represented in the MPA. Frequency of occurrence and relative abundance of sharks on BRUVS were significantly higher inside the De Hoop MPA than outside. Both protected and commercially exploited sharks species exhibited higher relative abundance inside the MPA. Relative abundance also increased inside the MPA with increasing distance from the reserve boundaries. Our findings suggest that no-take MPAs can be an effective tool for protecting shark species of conservation concern, including threatened endemics, particularly if the MPA adequately incorporates their preferred habitats.
... Various effects of MPAs on megafauna abundance, diversity and space use have been reported. Several studies found positive MPA effects on the abundance or diversity of sharks and rays in different parts of the world (Espinoza et al., 2020;Albano et al., 2021), even in relatively young MPAs (Jaiteh et al., 2016). Positive effects on space use were also identified for reef manta rays (Mobula alfredi), grey reef shark (Carcharhinus amblyrhynchos), bottlenose dolphin (Tursiops truncatus) and green sea turtle (Chelonia mydas) (Gilmour et al., 2022). ...
... Video-surveys conducted from drones or light aircraft (Kiszka et al., 2016;Mannocci et al., 2021;Desgarnier et al., 2022) have the potential to outperform traditional observerbased aerial surveys in terms of accuracy and precision in the derived abundance estimates (Colefax, Butcher & Kelaher, 2018;Kelaher et al., 2020a). While many studies have investigated the effect of MPAs on the abundance of megafauna species (Bond et al., 2012;Espinoza et al., 2014;Dwyer et al., 2020;Jabado et al., 2021;Flowers et al., 2022), few have simultaneously accounted for the effect of habitat, i.e. how the spatial heterogeneity of habitat influences species abundance (Osgood, McCord & Baum, 2019;Albano et al., 2021). Throughout this study, the word 'habitat' is used synonymously with 'benthic substrate habitat' (Diaz, Solan & Valente, 2004). ...
... Accounting for the effect of habitat on the abundance of megafauna is crucial because differences in habitat type and quality between protected and unprotected sites can confound analyses of MPA effects (Miller & Russ, 2014) and overlooking habitat can lead to erroneous conclusions about the effectiveness and utility of MPAs (Claudet, García-Charton & Lenfant, 2010). Also, knowing whether the level of protection or the quality of habitat is most critical for marine megafauna is key to guide future conservation strategies (Albano et al., 2021). ...
Overfishing and habitat degradation are major threats to marine megafauna worldwide. Marine protected areas (MPAs) are effective spatial conservation tools for reducing anthropogenic pressures on threatened species but their benefits for megafauna are still debated. While the effects of MPAs on species abundances are widely reported, few studies have simultaneously investigated the confounding effect of habitat.
This study aimed at disentangling the effects of coral reef habitat and spatial protection on megafauna densities in a shallow lagoon partly covered by a no‐take MPA in New Caledonia (South‐west Pacific).
Twenty replicates of aerial‐video surveys (representing 17 h of videos) were conducted during a 5‐month period to estimate and map the densities of five megafauna taxa (dugongs, sea turtles, sharks, Dasyatidae rays and Myliobatidae rays). A permutational multivariate analysis of variance was then applied to assess and disentangle the effects of coral reef habitat obtained from high‐resolution satellite imagery and spatial protection on megafauna taxa densities.
The analysis revealed a significant effect of protection for sharks and Myliobatidae, with observed densities respectively 9 and 3 times higher inside the MPA compared with outside. The results also highlighted a significant combined effect of habitat and protection for dugongs and Dasyatidae, as well as a significant effect of habitat alone for Dasyatidae. In contrast, no significant effect of habitat or protection was detected for sea turtles.
In conclusion, this study revealed positive effects of protection (alone or combined with habitat) for four of the five studied megafauna taxa, confirming the effectiveness of the current MPA. Future studies should be conducted over broader spatial and temporal scales to examine whether detected effects hold beyond the surveyed period and area.
... This pattern amplifies the need for conservation action if this species is exposed to heavy fishing pressure prior to reaching sexual maturity. While this species is protected in South Africa, it shares a common habitat preference as species targeted by commercial shark fisheries, including smoothhound (Mustelus spp.), soupfin (Galeorhinus galeus), and bronze whaler (Carcharhinus brachyurus) sharks (Albano et al., 2021), making this species vulnerable to bycatch. Accordingly, understanding the residency and movement patterns of juvenile smooth hammerheads in relation to areas exposed to and protected from commercial shark fisheries will help inform their conservation management. ...
... The De Hoop MPA is bordered by the fishing villages of Struisbaai and Arniston (to the west), and Witsand and Stilbaai (to the east), rendering its surrounding waters easily accessed by fishing vessels. The MPA contains several habitat types such as rocky reefs, sandy bottom, and corrugated rock, which are suitable for a variety of shark species (Albano et al., 2021). The unprotected waters adjacent to the MPA contain similar habitat types, which may prompt movement between the MPA and outside areas by mobile shark species. ...
... While baited remote underwater video surveys in the study area have demonstrated that the De Hoop MPA can benefit the local shark community (Albano et al., 2021), here we found that tagged juvenile smooth hammerheads spent extensive periods of time immediately adjacent to the eastern boundary of the De Hoop MPA, where they may be vulnerable to fishing. In fact, residency was highest in unprotected waters to the east of the MPA (at receiver UM001), an area of high biological productivity due to its proximity to the mouth of an estuary at the Breede River (Figure 2). ...
The coastal waters of South Africa are habitat to a diverse composition of sharks that are vulnerable to exploitation, many of which are endemic and/or classified by the International Union for Conservation of Nature (IUCN) Red List as Threatened or Data Deficient. Accordingly, this region has been identified as a global research and conservation priority for elasmobranchs. The De Hoop Marine Protected Area (MPA), in the Western Cape Province of South Africa, provides 288 km2 of no-take protection within its boundaries. However, the region experiences heavy commercial fishing, with two vessels actively operating as dedicated shark longliners (as of 2022). When crossing MPA boundaries, sharks are susceptible to capture by these vessels. Utilizing passive acoustic telemetry, the present study evaluated the movements of a threatened juvenile shark species, the smooth hammerhead (Sphyrna zygaena), both inside and adjacent to the De Hoop MPA, and along the greater coastline. Movement data from 20 tagged sharks were used to explore the effects of spatial, environmental, and management variables on their residency and movement patterns. Results indicate a high reliance of sharks on unprotected waters immediately adjacent to the MPA’s eastern boundary, an area of high biological productivity due to its proximity to the mouth of an estuary. Although some tagged sharks did move regionally along the South African coastline, individuals spent 95% of their days detected just outside the eastern boundary of the MPA, rendering them vulnerable to commercial shark longlining occurring there. These findings have conservation implications for smooth hammerhead sharks in South Africa and present an opportunity to revisit management practices that may optimize spatial protection for an important life stage of this threatened species.
... Marine reserves (MRs) or no-take marine protected areas are increasingly being advocated for the conservation of shark populations MacKeracher, Diedrich & Simpfendorfer, 2019;Albano et al., 2021). Marine reserves are zoned areas where commercial and recreational fishing, and any other form of extractive or destructive activity, are completely prohibited. ...
... Previous studies have demonstrated direct and positive conservation benefits that MRs can provide some shark species owing to the reduction of targeted fishing, bycatch and disturbance (da Silva et al., 2013;Dick & Jefferies, 2013;Albano et al., 2021), as well as the recovery of prey populations (Hooker & Gerber, 2004;Goetze & Fullwood, 2013). Even small MRs have been demonstrated to provide conservation benefits. ...
... Brooks et al., 2011;Tickler et al., 2017;Acuña-Marrero et al., 2018;Irigoyen et al., 2018), including during surveys of MRs (e.g. Bond et al., 2012;Goetze & Fullwood, 2013;Speed, Cappo & Meekan, 2018;Albano et al., 2021). Since shark distribution is known to be affected by a variety of factors, differences in habitat characteristics between the MRs and control sites were accounted for by including environmental variables in a multi-model inference approach. ...
With the increasingly imperilled status of shark populations, there is a pressing need to evaluate management solutions. Given the threats posed by fishing, marine reserves (MRs) present a promising option.
Ata Whenua (Fiordland) in the South Island of Aotearoa/New Zealand is an ideal location to investigate this phenomenon owing to the presence of several shark species in coastal MRs.
One‐hundred and sixty‐seven baited remote underwater video deployments were made in five MRs. A multi‐model inference approach using generalized linear modelling was used to assess the combined effect of the MRs on two trophic groups of coastal sharks.
Generalized linear modelling was used to assess the effect of protection on, firstly, the presence of broadnose sevengill sharks ( Notorynchus cepedianus ), while accounting for variations in environmental variables, and secondly, the combined relative abundance of mesopredatory sharks detected (spiny dogfish, Squalus acanthias ; school shark, Galeorhinus galeus ; and carpet shark, Cephaloscyllium isabellum ).
Mesopredators had a higher relative abundance in MRs by a factor of 2.5 and there was a strong significant effect of protection, suggesting that MRs have led to an increase in their abundance or a change in distribution. In contrast, there was no effect of protection detected for sevengill sharks.
It is concluded that the relatively small (<40 km ² ) MRs sampled do not provide conservation benefits for a large, mobile shark, but that they are potentially large enough to offer protection for mesopredatory sharks with smaller home ranges.
To be effective for shark conservation, we therefore recommend that MRs need to be appropriately sized for the ranging behaviour of the target species for protection.
... The question of how MPAs can be used to protect chondrichthyans was first addressed over two decades ago (Bonfil, 1999). There is now a growing body of evidence that no-take reserves actually benefit chondrichthyan populations (Garla et al., 2005;Heupel et al., 2009;Goetze and Fullwood, 2012;Knip et al., 2012;da Silva et al., 2013;Bond et al., 2017;White et al., 2017;Juhel et al., 2019;Albano et al., 2021). It was demonstrated that MPAs may be most effective for juveniles due to smaller individuals being more site attached to specific reefs Garla et al., 2005;Pikitch et al., 2005;Robbins et al., 2006;Heupel et al., 2010). ...
... In particular, the coastal MPAs extend for 34% of the South African coastline and are fundamental for the protection of important habitats, such as rocky reefs and kelp forests (Fielding, 2021). Some studies have been done in recent years focusing on the effects of MPAs on chondrichthyans (de Vos et al., 2015;Osgood et al., 2019;Albano et al., 2021). Osgood et al. (2019) focused on a small MPA (Betty's Bay MPA) and on a seasonal marine reserve with restrictions put in place only for five months a year (Walker Bay Whale Sanctuary MPA), and in both cases, the chondrichthyan assemblages were not significantly affected by the presence of both MPAs. ...
... Osgood et al. (2019) focused on a small MPA (Betty's Bay MPA) and on a seasonal marine reserve with restrictions put in place only for five months a year (Walker Bay Whale Sanctuary MPA), and in both cases, the chondrichthyan assemblages were not significantly affected by the presence of both MPAs. Albano et al. (2021), on the other hand, found that sharks are significantly protected by the presence of the old and large De Hoop MPA. Results on the effects of marine reserves on chondrichthyan assemblages in South African waters are therefore variable based on a series of environmental factors and depending on the size and management of the MPA itself. ...
Chondrichthyans are threatened worldwide due to their life-history traits combined with a plethora of anthropogenic impacts that are causing populations to collapse. Marine Protected Areas (MPAs) are a conservation option, but their efficacy for chondrichthyans is still unclear. Conservation efforts might be challenging especially in developing countries, due to a lack of resources and monitoring and limited data and stakeholder support. Here Baited Remote Underwater Stereo-Video systems (stereo-BRUVs) were deployed inside and outside a small partially protected MPA (Robberg MPA, Western Cape, South Africa) to assess the status of cartilaginous fishes’ assemblages and to investigate the potential benefits derived from the presence of a marine reserve. Overall, 19 chondrichthyan species in 11 different families were observed. Chondrichthyans were observed in 78.5% of the sites and, of these, 89.7% of the MPA sites showed at least one chondrichthyan, while only in the 67.5% of surrounding exploited sites a cartilaginous fish was sighted. The presence of the MPA had a significant effect on the relative abundance of batoids, threatened species and local endemics, with more observations inside the MPA than outside, indicating the potential benefit of marine reserves on species that are more vulnerable to fishing pressure. Relative abundance was generally higher inside the bay than in the exposed area, and both relative abundance and species richness decreased significantly with depth. The analysis of the body length showed that the 35.5% of species had an average body length below maturity length, indicating that the area might be used as nursery ground for different species. This study provides evidence that MPAs, even though small and partially protected, can provide benefits for chondrichthyans, specifically to threatened species, endemic species and lesser-known species. Importantly, different environmental parameters must be considered to maximize the benefits an MPA can provide.
... Spatial or temporal fisheries closures are a variant of MPAs, and have been described as "other effective area-based conservation measures" (OECMs). However, some studies on migratory fishes suggest that MPAs, if properly placed, can have disproportionately positive benefits (Bond et al., 2017;Daley et al., 2015;Kerwath et al., 2009), and some locally exploited species can benefit from protection within MPAs (Albano et al., 2021;da Silva et al., 2013da Silva et al., , 2021. A network of well-placed MPAs has been shown to be one of the most effective measures to protect certain species of sharks and rays as this enables habitat connectivity and reduces exposure to fisheries across several areas (Simpendorfer and Cook, 2019). ...
... Specifically, this MPA was identified as a nursery ground due to the large concentrations of neonate and juvenile individuals found in higher abundances over several years within the notake area (da Silva et al., 2021). Another study within the De Hoop MPA demonstrated that medium to small endemic shark species have greatly benefited from the establishment of a no-take zone and have shown higher relative abundance within the MPA compared with areas outside the MPA (Albano et al., 2021). Whilst this study did not take into account aggregation areas, areas of highest chondrichthyan diversity were modelled and this can be seen as a start to assess the representation of sharks and rays in our MPA network. ...
... Spatial or temporal fisheries closures are a variant of MPAs, and have been described as "other effective area-based conservation measures" (OECMs). However, some studies on migratory fishes suggest that MPAs, if properly placed, can have disproportionately positive benefits (Bond et al., 2017;Daley et al., 2015;Kerwath et al., 2009), and some locally exploited species can benefit from protection within MPAs (Albano et al., 2021;da Silva et al., 2013da Silva et al., , 2021. A network of well-placed MPAs has been shown to be one of the most effective measures to protect certain species of sharks and rays as this enables habitat connectivity and reduces exposure to fisheries across several areas (Simpendorfer and Cook, 2019). ...
... Specifically, this MPA was identified as a nursery ground due to the large concentrations of neonate and juvenile individuals found in higher abundances over several years within the notake area (da Silva et al., 2021). Another study within the De Hoop MPA demonstrated that medium to small endemic shark species have greatly benefited from the establishment of a no-take zone and have shown higher relative abundance within the MPA compared with areas outside the MPA (Albano et al., 2021). Whilst this study did not take into account aggregation areas, areas of highest chondrichthyan diversity were modelled and this can be seen as a start to assess the representation of sharks and rays in our MPA network. ...
... Spatial or temporal fisheries closures are a variant of MPAs, and have been described as "other effective area-based conservation measures" (OECMs). However, some studies on migratory fishes suggest that MPAs, if properly placed, can have disproportionately positive benefits (Bond et al., 2017;Daley et al., 2015;Kerwath et al., 2009), and some locally exploited species can benefit from protection within MPAs (Albano et al., 2021;da Silva et al., 2013da Silva et al., , 2021. A network of well-placed MPAs has been shown to be one of the most effective measures to protect certain species of sharks and rays as this enables habitat connectivity and reduces exposure to fisheries across several areas (Simpendorfer and Cook, 2019). ...
... Specifically, this MPA was identified as a nursery ground due to the large concentrations of neonate and juvenile individuals found in higher abundances over several years within the notake area (da Silva et al., 2021). Another study within the De Hoop MPA demonstrated that medium to small endemic shark species have greatly benefited from the establishment of a no-take zone and have shown higher relative abundance within the MPA compared with areas outside the MPA (Albano et al., 2021). Whilst this study did not take into account aggregation areas, areas of highest chondrichthyan diversity were modelled and this can be seen as a start to assess the representation of sharks and rays in our MPA network. ...
The International Union for Conservation of Nature (IUCN) estimates that over a third of all chondrichthyan species (sharks, rays and chimaeras) are threatened with extinction, primarily by overfishing (as target or bycatch species). Owing to the wide-ranging distributions of many chondrichthyans, they are often overlooked in marine protected area (MPA) design. South Africa is a biodiversity hotspot for chondrichthyan species diversity, and to improve the conservation status of these species in the country's continental exclusive economic zone (EEZ), we collaborated widely to collate existing occurrence data. Ensemble models were developed for 87 species' distributions, which informed a systematic conservation planning analysis for 64 threatened and endemic species. We assessed the current representation of these species in South Africa's MPA network and identified priority areas for protection, avoiding fishing pressure where possible. Results show that many MPAs are well placed to protect chondrichthyans, especially along the east coast (KwaZulu-Natal province). Unfortunately, permissive fishing regulations within many MPA zones reduces their effectiveness at protecting chondrichthyans. Improved regulations designed to protect chondrichthyans within all MPAs should be considered a high priority. Priority areas for increased spatial protection were identified along the west coast continental shelf, the Agulhas Bank off the south coast, and south coast embayments. We found that supplementing the current MPA network by an additional 5 % of the EEZ would be sufficient to protect >30 % of the range of all 64 species, provided there is adequate enforcement. As South Africa prepares to expand its MPA estate to meet international targets, these findings can ensure that chondrichthyans are well represented.
... However, like global shark populations, South Africa's shark populations have experienced dramatic declines [12,23,24]. Elasmobranchs are exposed to heavy fishing pressure and overexploitation through target fisheries and bycatch via non-target fisheries [1,7,26], and recent research has shown these to be the most significant threats facing sharks both in South Africa and worldwide [14,24]. ...
Global shark populations are in serious decline, especially due to overexploitation through fisheries, whose impact is often increased by a lack of proper management regulations and enforcement. South Africa’s population of chondrichthyan fauna is one of the most diverse in the world, with high rates of endemic and imperiled elasmobranch species. South Africa has been lauded as a global leader in shark conservation through progressive management legislation, such as the 2013 National Plan of Action for the Conservation and Management of Sharks (NPOA-Sharks I). However, South Africa’s shark populations have continued to decline. This study aimed to survey stakeholders’ (students, academics, government representatives, conservationists, recreational anglers, commercial fishers, and tourism-related stakeholders) perspectives on the efficacy of NPOA-Sharks I in managing and enforcing fisheries regulations and to advise the 2022 NPOA-Sharks II approach concerning the conservation of South African elasmobranchs. A total of 89 stakeholders participated in an online questionnaire survey launched in 2021. Most stakeholders viewed the NPOA-Sharks I as somewhat appropriate, South Africa’s current exploitation of shark stocks as unsustainable and management and enforcement of regulations as inadequate. Commercial fishing and lack of enforcement were ranked as the two most pressing issues facing South Africa’s sharks. Similarly, the expert review panel found limited progress (<50%) made in the implementation of the NPOA-Sharks I concerning regulatory tools and sustainable management and called for improved monitoring, surveillance and enforcement of compliance regulations across fisheries as one of the top recommendations for immediate implementation in NPOA-Sharks II. However, the majority of action items under the “Sustainable Management” issue cluster in NPOA-Sharks II suggest a reassessment or reestablishment of existing regulations or the development of new regulatory tools with few specifics provided, reflective of a disconnect between what the lead government agency responsible for the management of South Africa’s sharks, the Department of Forestry, Fisheries and the Environment (DFFE), perceives to be effective and what stakeholders experience concerning shark conservation in South Africa. What was perceived by the national management agency as effective concerning shark conservation in South Africa was not necessarily experienced as such by the stakeholders. There is a need for increased collaboration among stakeholders and significant improvements in the practical management of South African fisheries for shark conservation, which is now also suggested in the NPOA-Sharks II.
... There is clear potential for environmental variability to influence the abundance and behavior of planktivorous elasmobranchs, and other marine species. However, studies on the efficacy of marine protected areas, assessments of elasmobranch population dynamics, and studies of elasmobranch movement ecology do not always account for environmental factors or simply include one environmental covariate (e.g., temperature or depth) (Goetze and Fullwood 2013, Juhel et al. 2018, Albano et al. 2021, Hammerschlag et al. 2022. However, incorporating a broad array of environmental factors, especially those associated with climate change is essential in making well-supported ecological inferences and generating critical data for management. ...
Several studies have found predictable relationships between the behavior of planktivores and environmental conditions, suggesting that planktivores may be especially sensitive to environmental change. However, many studies to date are based on limited observations, include few of the many environmental covariates which could influence planktivores, and do not occur over long enough time periods to make inferences about the potential effects of environmental change. As such, long term datasets on planktivores are necessary to disentangle the potential impacts of oceanographic and environmental variability. In this study, to elucidate the relationship between plankivores and environmental variability, we use data obtained over the last 28 years by a small group of divemasters at Cocos Island, Costa Rica, one of the oldest marine reserves in the world. We found that, in general, for planktivorous elasmobranchs, several environmental variables, such as, chlorophyll A, lunar cycle, and salinity have clear influences on their occurrence and relative abundances. We found that in the phases of lower illuminations, there were significant increases in abundance of mobula rays. Specifically, a 0.10 mg/m ³ increase in Chlorophyll A correlated with 26% decrease in whale sharks. We found that increases in salinity correlated with increases in mobula abundance but did not correlate with observations of mantas or whale sharks. We also found that omission of environmental covariates can lead to overprediction and underprediction of relative abundances. Our findings highlight the need to take environmental conditions into account when evaluating the efficacy of marine protection.
... Furthermore, approximately one-third of all individuals have been tagged within South African MPAs and, at time of writing, approximately 40% (n = 103) of the 251 active receivers were situated within MPAs ( Figure 6). These partner projects within MPAs aim to (i) evaluate the efficacy of the De Hoop Nature Reserve in protecting endemic and threatened shark species, including endemic catsharks (Albano et al., 2021); (ii) investigate the movements of giant kingfish Caranx ignobilis in the Mtentu Estuary within the Pondoland MPA and their connectivity with surrounding areas (Dixon, 2022), including their known spawning aggregation site in southern Mozambique (Daly et al., 2019); (iii) investigate the connectivity between the Pondoland and St Lucia MPAs using catface rockcod Epinephelus andersoni as the focal species; (iv) investigate the movements of green jobfish Aprion virescens and potato bass Epinephelus tukula in the iSimangaliso Wetland Park (an MPA); (v) assess the influence of fishing pressure on the behaviour and activity of an endemic sparid red Roman Chrysoblephus laticeps tagged in the Tsitsikamma National Park MPA; and (vi) understand how the resident sparid white steenbras responds to oceanographic features within the Greater Addo Elephant National Park MPA ( Figure 6). Together, these projects highlight the conservation potential that the ATAP has to inform whether vulnerable and endemic species are being effectively protected by the current MPA zonation in South Africa. ...
The Blue Economy is a global initiative aimed at using marine resources to create economic viability and environmental sustainability. While successes have been reported, for example, in Europe and China, examples of African successes are notably missing. Abject poverty, unemployment and food insecurity are everyday concerns on the African continent; however, its large latitudinal coverage gives rise to extremely biodiverse marine fauna, which could promote socio-economic development of coastal communities through initiatives such as sustainably-managed fisheries. In order to improve sustainability via improved management, information on a species and its habitat is needed, particularly how it moves and in which areas it occurs. Acoustic telemetry is a powerful tool used to determine the movements of aquatic animals, the success of which has led to the development of several large-scale networks throughout the globe, including South Africa’s Acoustic Tracking Array Platform. This network, formally in place for the last decade, has now matured, and data are revealing insights into residency, habitat connectivity and transboundary movements of a multitude of animals, with some species having been continually detected for the past 10 years. These data are also actively being incorporated into marine spatial planning efforts, with the aim of protecting threatened and endemic species. Due to knowledge generation, successful benefit-sharing arrangements, and dedication to engage with the public and other stakeholder groups, the ATAP represents a highly successful example of ocean stewardship in Africa.
... To accommodate the needs of various stakeholders, management planning typically includes areas where fishing is excluded (No-Take Areas) and other areas where some types of extractive activities are restricted. Several studies have used BRUVs as a tool to evaluate the efficacy of marine reserves on shark abundance in both tropical and temperate reefs 9,10 . The extent to which such strategies effectively protect highly mobile species such as sharks is a subject of debate given the size of their ranges relative to the area of protection (Ward-Paige et al. 2012). ...
Quantifying the drivers of population size in reef sharks is critical for the development of appropriate conservation strategies. In north-west Australia, shark populations inhabit coral reefs that border growing centres of human population, industry, and tourism. However, we lack baseline data on reef sharks at large spatial scales (hundreds of km) that might enable managers to assess the status of shark populations in the face of future development in this region. Here, we examined the occurrence, abundance and behaviour of apex (Galeocerdo cuvier, Carcharhinus plumbeus) and reef (C. amblyrhynchos, C. melanopterus, Triaenodon obesus) sharks using > 1200 deployments of baited remote underwater stereo-video systems (stereo-BRUVs) across > 500 km of coastline. We found evidence for species-specific influences of habitat and fishing activities on the occurrence (probability of observation), abundance (MaxN) and behaviour of sharks (time of arrival to the stereo-BRUVs and likelihood of feeding). Although the presence of management zoning (No-take areas) made little difference to most species, C. amblyrhynchos were more common further from boat ramps (a proxy of recreational fishing pressure). Time of arrival for all species was also influenced by distance to boat ramp, although patterns varied among species. Our results demonstrate the capacity for behavioural metrics to complement existing measures of occurrence and abundance in assessing the potential impact of human activities on shark populations.
Understanding how environmental drivers influence shark and ray spatial and temporal patterns can provide crucial knowledge for their evidence-based protection and long-term monitoring. However, information on which drivers of variation are most important for elasmobranch communities on soft sediments is limited. Using baited remote underwater stereo-video systems (stereo-BRUVs), we investigated how seasonal and environmental variables affected the elasmobranchs of the iSimangaliso Wetland Park marine protected area (MPA) in South Africa (SA). In total, 11 species were identified from 48 sites between 12 m and 33 m water depth in a sandy habitat. While species richness was similar across seasons, the total abundance of elasmobranchs recorded was higher in winter than summer. The species assemblage composition varied significantly between seasons, with the Human’s whaler shark Carcharhinus humani prevalent in summer and the Critically Endangered whitespotted wedgefish Rhynchobatus djiddensis more abundant during winter. Most species were sighted throughout the entire depth range, but rays were more common in shallower waters (< 25 m depth), while C. humani and R. djiddensis were more common in the deeper depth zone of this study. This research provides baseline information about this previously unexplored sandy habitat for elasmobranchs in a site of regional and global significance. Records of species of conservation concern in the sampling area highlight the importance of protecting sand environments within an MPA.
Human activities have led to the loss of critical habitats for aquatic species at such an accelerated rate that habitat modification is considered a leading threat to biodiversity. Sharks and rays are considered the second most threatened group of vertebrates that have also suffered from habitat loss, especially in nursery grounds and reef-associated species. In this sense, actions toward the conservation of critical grounds for species survival are urgently needed, especially for those threatened with extinction. This study aimed to gather and provide information on the worldwide distribution and habitat association of the ‘vulnerable’ Atlantic Nurse Shark Ginglymostoma cirratum through a literature review performed at the Dimensions research database. A total of 30 studies published between 1950 and 2021 were retained since they defined at least the type of habitat in which G. cirratum was associated. Most studies covered the Floridian ecoregion, where G. cirratum is more common and abundant. Reefs, seagrass, sandy, rocky, mangrove, and macroalgae accounted for the majority of habitat associations, with a higher diversity of habitats detected within marine protected areas (MPAs). Ginglymostoma cirratum was recorded at a maximum depth of 75 m, temperatures ranging from 25 °C to 34 °C, and salinities between 31 and 38 ppt. Neonates were associated with shallower habitats (
The bull shark (Carcharhinus leucas Valenciennes, 1839) is a large, primarily coastally distributed shark famous for its ability to penetrate far into freshwater bodies in tropical, subtropical, and warm-temperate climates. It is a cosmopolitan species with a geographical range that includes the coastlines of all major ocean basins (Atlantic Ocean, Indian Ocean, Pacific Ocean). As a consequence, freshwater occurrences of C. leucas are possible everywhere inside its geographic range. Carcharhinus leucas is a fully euryhaline, amphidromous species and possibly the widest-ranging of all freshwater tolerating elasmobranchs. This species is found not only in river systems with sea access that are not interrupted by human impediments but in hypersaline lakes as well. Rivers and estuaries are believed to be important nursery grounds for C. leucas, as suggested by observations of pregnant females in estuaries and neonates with umbilical scars in rivers and river mouths. Due to the physical capability of this species to enter riverine systems, the documentation of its occurrence in fresh and brackish water is essential for future conservation plans, fishery inspections, and scientific studies that focus on the link between low salinity habitats, shark nurseries, and feeding areas. The author’s review of the available literature on C. leucas revealed the absence of a comprehensive overview of fresh and brackish water localities (rivers and associated lakes, estuaries) with C. leucas
records. The purpose of this literature review is to provide a global list of rivers, river systems, lakes, estuaries, and lagoons with records and reports of this species, including a link to the used references as a base for regional, national, and international conservation strategies. Therefore, the objective of this work is to present lists of fresh and brackish water habitats with records of C. leucas as the result of an extensive literature review and analysis of databases. This survey also took into account estuaries and lagoons, regarding their function as important nursery grounds for C. leucas. The analysis of references included is not only from the scientific literature, but also includes semi-scientific references and the common press if reliable. The result of 415 global fresh and brackish water localities with evidence of C. leucas highlights the importance of these habitats for the reproduction of this species. Moreover, gaps in available distribution maps are critically discussed as well as interpretations and conclusions made regarding possible reasons for the distribution range of C. leucas, which can be interpreted as the result of geographic circumstances, but also as a result of the current state of knowledge about the distribution of this species. The results of the examination of available references were used to build a reliable and updated distribution map for C. leucas, which is also presented here.
The rapid expansion of human activities threatens ocean-wide biodiversity. Numerous marine animal populations have declined, yet it remains unclear whether these trends are symptomatic of a chronic accumulation of global marine extinction risk. We present the first systematic analysis of threat for a globally distributed lineage of 1,041 chondrichthyan fishes-sharks, rays, and chimaeras. We estimate that one-quarter are threatened according to IUCN Red List criteria due to overfishing (targeted and incidental). Large-bodied, shallow-water species are at greatest risk and five out of the seven most threatened families are rays. Overall chondrichthyan extinction risk is substantially higher than for most other vertebrates, and only one-third of species are considered safe. Population depletion has occurred throughout the world's ice-free waters, but is particularly prevalent in the Indo-Pacific Biodiversity Triangle and Mediterranean Sea. Improved management of fisheries and trade is urgently needed to avoid extinctions and promote population recovery.
Given the recent trend towards establishing very large marine protected areas (MPAs) and the high potential of these to contribute to global conservation targets, we review outcomes of the last decade of marine conservation research in the British Indian Ocean Territory (BIOT), one of the largest MPAs in the world. The BIOT MPA consists of the atolls of the Chagos Archipelago, interspersed with and surrounded by deep oceanic waters. Islands around the atoll rims serve as nesting grounds for sea birds. Extensive and diverse shallow and mesophotic reef habitats provide essential habitat and feeding grounds for all marine life, and the absence of local human impacts may improve recovery after coral bleaching events. Census data have shown recent increases in the abundance of sea turtles, high numbers of nesting seabirds and high fish abundance, at least some of which is linked to the lack of recent harvesting. For example, across the archipelago the annual number of green turtle clutches (Chelonia mydas) is ~ 20,500 and increasing and the number of seabirds is ~ 1 million. Animal tracking studies have shown that some taxa breed and/or forage consistently within the MPA (e.g. some reef fishes, elasmobranchs and seabirds), suggesting the MPA has the potential to provide long-term protection. In contrast, post-nesting green turtles travel up to 4000 km to distant foraging sites, so the protected beaches in the Chagos Archipelago provide a nesting sanctuary for individuals that forage across an ocean basin and several geopolitical borders. Surveys using divers and underwater video systems show high habitat diversity and abundant marine life on all trophic levels. For example, coral cover can be as high as 40-50%. Ecological studies are shedding light on how remote ecosystems function, connect to each other and respond to climate-driven stressors compared to other locations that are more locally impacted. However, important threats to this MPA have been identified, particularly global heating events, and Illegal, Unreported and Unregulated (IUU) fishing activity, which considerably impact both reef and pelagic fishes.
Decades of overexploitation have devastated shark populations, leaving considerable doubt as to their ecological status1,2. Yet much of what is known about sharks has been inferred from catch records in industrial fisheries, whereas far less information is available about sharks that live in coastal habitats³. Here we address this knowledge gap using data from more than 15,000 standardized baited remote underwater video stations that were deployed on 371 reefs in 58 nations to estimate the conservation status of reef sharks globally. Our results reveal the profound impact that fishing has had on reef shark populations: we observed no sharks on almost 20% of the surveyed reefs. Reef sharks were almost completely absent from reefs in several nations, and shark depletion was strongly related to socio-economic conditions such as the size and proximity of the nearest market, poor governance and the density of the human population. However, opportunities for the conservation of reef sharks remain: shark sanctuaries, closed areas, catch limits and an absence of gillnets and longlines were associated with a substantially higher relative abundance of reef sharks. These results reveal several policy pathways for the restoration and management of reef shark populations, from direct top-down management of fishing to indirect improvement of governance conditions. Reef shark populations will only have a high chance of recovery by engaging key socio-economic aspects of tropical fisheries.
Effective sampling of marine communities is essential to provide robust estimates of species richness and abundance. Baited Remote Underwater Video Stations (BRUVS) are a useful tool in assessment of fish assemblages, but research on the optimal sampling period required to record common and rare elasmobranch species is limited. An appropriate ‘soak time’ (time elapsed between settlement of the BRUVS on the seabed and when it is hauled off the seabed) requires consideration, since longer soak times may be required to record species rare in occurrence, or sightings in areas of generally low elasmobranch abundance. We analysed 5352 BRUVS deployments with a range of soak times across 21 countries in the Coral Triangle and Pacific Ocean, to determine the optimal soak time required for sampling reef-associated elasmobranchs, considering species rarity, and community abundance at each site. Species were categorised into 4 ‘rarity’ groups (very rare to common), by their relative occurrence in the dataset, defined simply by the proportion of BRUVS on which they occurred. Individual BRUVS were categorised into 3 ‘abundance’ groups (low to high) by overall relative elasmobranch abundance, defined as total number of all elasmobranchs sighted per unit of sampling effort. The effects of BRUVS soak times, and levels of rarity and abundance groupings, on the time to first sighting (TFS) and time to maximum number of elasmobranchs observed (tMaxN) were examined. We found that TFS occurred earlier for species groups with high occurrence, and on BRUVS with high elasmobranch abundance, yet longer soak times were not essential to observe rarer species. Our models indicated an optimum of 95% of both sighting event types (TFS, tMaxN) was recorded within 63–77 minutes, and a soak time of 60 minutes recorded 78–94% of the elasmobranch sighting events recorded (78–94% of TFS events and 82–90% of tMaxN events), when species rarity and abundance on BRUVS was accounted for. Our study shows that deployments of ~ 77 minutes are optimal for recording all species we observed, although 60 minutes soak time effectively samples the majority of elasmobranch species in shallow coral reef habitats using BRUVS.
Conservation surrogates, such as umbrella and flagship species, could help focus South Africa’s limited resources for research and management and enhance the conservation gains from marine protected areas (MPAs). Sharks, rays and chimaeras (Chondrichthyes), which are charismatic and ecologically diverse, are potential umbrella candidates, but tests of the ecological suitability of putative marine umbrella species are lacking. Using baited remote underwater video in and around two MPAs in the Western Cape Province, we assessed the potential of chondrichthyans as an umbrella species-complex by quantifying the relationships and co-occurrence patterns between chondrichthyan abundance and diversity and those of other taxa (primarily teleosts and crustaceans). Sites with abundant chondrichthyans, with catsharks or large sharks (>1 m total length), all had significantly greater abundance and diversity of these other taxa, and associations with species of commercial and conservation interest (e.g. roman Chrysoblephus laticeps). Endemic scyliorhinids (notably dark catshark Haploblepharus pictus) and the broadnose sevengill shark Notorynchus cepedianus also had many strong positive co-occurrences (28% and 21% of interactions, respectively). The puffadder catshark H. edwardsii had the highest centrality of any species, denoting its high connectedness to other taxa. Overall, chondrichthyans, especially the dark and puffadder catsharks and the broadnose sevengill shark, show strong potential as an umbrella species-complex in South Africa.
Synthesis report for South Africa's National Biodiversity Assessment 2011
Common smoothhound shark (Mustelus mustelus) are medium sized sharks distributed from the Mediterranean down to the SouthWest Indian Ocean. Commercially it is one of the top five most valuable shark species mainly caught as target or by-catch by the demersal shark longline fishery, commercial linefishery and the inshore trawl fishery. Total catches across all fisheries increased from 16 to 252 t between 1990 and 2010, thereafter catches have declined to 124 t in 2016. An initial trend analysis of the available fisheries-independent abundance indices with JARA indicated that there was a-42.3% population decline over the observation period (1991-2016) which translated into a more than 70% probability that smoothhound shark has declined by 30% since 1991. The projected decline over three generation lengths was 63.3% with 55.5% probability that smoothhound shark would fall into the Endangered category when assessed in accordance to the IUCN Red List criteria. The full stock assessment of smoothhound shark was conducted with JABBA, a Bayesian State-Space Surplus Production Model. The four alternative scenarios estimated MSY between 85 and 118 tons and median estimates for B/B MSY from the four scenarios ranged between 1.12 and 1.27. Biomass as a proportion of pristine biomass (B/K) ranged between 0.56 and 0.64. All four scenarios produce B/B MSY trajectories that decrease between 1990 and 2016, in conjunction with a steady increase of F/F MSY , with the exception of the years 2011 and 2012. Kobe biplots for three out of four scenarios indicated that the South African smoothhound shark stock was not overfished but subject to overfishing. Only the most optimistic scenario predicted a 65% probability that the smoothhound shark was not overfished and that overfishing was not occurring, while the other three scenarios estimated more than 50% probabilities that current fishing mortality is unsustainable (F/F MSY > 1). The sensitivity of the base-case to the exclusion of varying indices was inconsequential to the classification of current biomass levels as sustainable (B/B MSY > 1), but revealed notable effects on F/F MSY. Runs tests revealed that there was no data conflict between trawl surveys and research angling abundance indices. The retrospective analysis showed a moderate retrospective pattern over last decade with expectations (retrospective peel) typically more pessimistic then updated model. In general, current fishing levels (F/F MSY) are probably imprecisely estimated and sensitive to alternative model assumptions, while estimated B/B MSY provide a higher degree of confidence in the predictive capabilities of the assessment. To ensure that smoothound shark biomass has an increasing (positive) trajectory by 2024 with an 80% probability, a decrease in catch to below 75 tons is required.
Threatened chondrichthyan diversity is high in developing countries where scarce resources, limited data, and minimal stakeholder support often render conservation efforts challenging. As such, data on many species, including many evolutionarily distinct endemics, is poor in these countries and their conservation status and habitat needs remain uncertain. Here, we used baited remote underwater videos (BRUVs; n = 419) conducted at 167 sites over two years to assess the frequency of occurrence (FO), relative abundance, diversity, and structure of chondrichthyan assemblages in one of the world’s chondrichthyan biodiversity and endemism hotspots, South Africa. We compared chondrichthyan assemblages across three habitat types, and between unprotected and protected areas (a small marine protected area [MPA] and a larger, seasonal whale sanctuary). Although in total we observed 18 chondrichthyan species (11 families), over half of all observations were of just two species from the same family of mesopredatory endemic catsharks; only 8.8% were larger shark species. These mesopredatory species do not appear to be threatened, but some skates and larger shark species, including some endemics, were much rarer. Overall chondrichthyan FO was high (81% of all BRUVs); FO was higher in kelp (100% of BRUVS) and reef (93%) sites than at sites in sandy habitat (63%), which had a distinct chondrichthyan community. Independent of habitat, the chondrichthyan community did not relate strongly to protection. Because sites with kelp and reef habitat were rare in the whale sanctuary, this protected area had a lower chondrichthyan FO (67% of BRUVs) than either unprotected sites (81%) or those in the small MPA (98%), as well as having lower chondrichthyan relative abundance and species richness. Our study provides evidence of the importance of distinct habitat types to different chondrichthyan species, and suggests that even small MPAs can protect critical habitats, such that they may provide safe refuge for endemic species as anthropogenic pressures increase.
Many of the world’s shark populations are in decline, indicating the need for improved conservation and management. Well managed and appropriately located marine parks and marine protected areas (MPAs) have potential to enhance shark conservation by restricting fisheries and protecting suitable habitat for threatened shark populations. Here, we used shark occurrence records collected by commercial fisheries to determine suitable habitat for pelagic sharks within the Australian continental Exclusive Economic Zone (EEZ), and to quantify the amount of suitable habitat contained within existing MPAs. We developed generalised linear models using proportional occurrences of pelagic sharks for three families: Alopiidae (thresher), Carcharhinidae (requiem), and Lamnidae (mackerel) sharks. We also considered aggregated species from the Lamnidae and Carcharhinidae families (‘combined sharks’ in the models). Using a set of environmental predictors known to affect shark occurrence, including chlorophyll-a concentration, salinity, sea surface temperature, and turbidity, as well as geomorphological, geophysical, and sedimentary parameters, we found that models including sea surface temperature and turbidity were ranked highest in their ability to predict shark distributions. We used these results to predict geographic regions where habitat was most suitable for pelagic sharks within the Australian EEZ, and our results revealed that suitable habitat was limited in no-take zones within MPAs. For all shark groupings, suitable habitats were found mostly at locations exposed to fishing pressure, potentially increasing the vulnerability of the pelagic shark species considered. Our predictive models provide a foundation for future spatial planning and shark management, suggesting that strong fisheries management in addition to MPAs is necessary for pelagic shark conservation.
The smooth hammerhead shark Sphyrna zygaena is known to display a high degree of site fidelity to specific areas along the South African coastline. This species is vulnerable to overfishing and steep declines have been noted globally. In this study, a dual marker approach was used to investigate the spatial and temporal genetic variation of juvenile S. zygaena across the south and east coast of South Africa. Kinship of individuals was determined within and across cohorts from juvenile S. zygaena sampled in Mossel Bay, a putative pupping ground. Significant genetic differentiation (supported by F-statistics, multivariate analysis and Bayesian clustering) was evident between individuals sampled from the warm temperate south coast and the subtropical east coast, with asymmetric gene flow between regions. Distinct genetic composition was also revealed between sampling years, with different levels of relatedness within and among cohorts, indicating different temporal populations utilizing Mossel Bay annually. Based on these results, further investigation of S. zygaena populations across a wider region is warranted in order to make recommendations regarding conservation management of this vulnerable coastal shark.
Effective ocean management and conservation of highly migratory species depends on resolving overlap between animal movements and distributions and fishing effort. Yet, this information is lacking at a global scale. Here we show, using a big-data approach combining satellite-tracked movements of pelagic sharks and global fishing fleets, that 24% of the mean monthly space used by sharks falls under the footprint of pelagic longline fisheries. Space use hotspots of commercially valuable sharks and of internationally protected species had the highest overlap with longlines (up to 76% and 64%, respectively) and were also associated with significant increases in fishing effort. We conclude that pelagic sharks have limited spatial refuge from current levels of high-seas fishing effort. Results demonstrate an urgent need for conservation and management measures at high-seas shark hotspots and highlight the potential of simultaneous satellite surveillance of megafauna and fishers as a tool for near-real time, dynamic management.
Marine protected areas (MPAs) are not designed the same, nor are they equally effective. Efficacy of MPAs is frequently gauged by measuring the direct ecological responses of fish communities. However measuring the indirect, or knock-on effects from protection can provide additional insight into MPA effectiveness at the community level. Here we applied trait-based and community analyses to investigate MPA effectiveness by evaluating both direct and indirect effects of protection on fish assemblages using baited remote underwater stereo-video data from inside and outside 5 no-take MPAs along the South African coastline. The trait-based analyses indicated the presence of a significant overall direct effect (increased abundance of mature individuals targeted by fisheries) and indirect effects (reduction of the abundance of species not targeted by fisheries) inside MPAs, and highlighted that fish maturity is an essential trait to incorporate when assessing direct effects of protection. However, investigation of the species data of the individual MPAs showed positive reserve effects at the community level (both direct and indirect effects) in only 3 MPAs. For the most part these results conform with current theories on the factors that contribute to MPA effectiveness. Yet, one old, large and isolated no-take MPA showed no direct effects of protection, which is attributed to the lack of adequate offshore reef habitat throughout this MPA. While these results support the value of MPAs as ecosystem management tools, they highlight the need for appropriate site selection when designing MPAs.
Marine protected areas (MPAs) are increasingly advocated for the conservation and management of sharks and rays. However, substantial uncertainty remains regarding which species can benefit from MPAs. Meanwhile, area-focused protection targets have spurred recent and rapid gains in the creation of large MPAs, many of which carry vague objectives set by a diverse group of stakeholders with potentially different notions of "success." Here, we capture and critically evaluate current views on the use of MPAs for shark and ray conservation. Through interviews with scientists, MPA managers, fisheries experts, conservation practitioners, advocates and policy experts (n = 53), we demonstrate a variety of perspectives regarding: (a) the effectiveness of MPAs as a tool for shark and ray conservation; (b) which factors influence the success of MPAs for sharks and rays; and (c) the desired outcomes of these MPAs. While MPAs created specifically for sharks and rays were viewed to be slightly more effective than regular MPAs as a tool for shark and ray conservation, both were generally considered insufficient in isolation. Despite greater emphasis on social success factors (e.g., local support) over biophysical success factors (e.g., size), biological outcomes (e.g., increased abundance) were prioritized over social outcomes (e.g., livelihood benefits). We argue that a stronger focus on achieving social outcomes can enhance the potential for MPAs to benefit sharks and rays. In revealing current thinking regarding the drivers and indicators of MPA success for sharks and rays, the results of this study can inform efforts to conserve and manage these species. K E Y W O R D S effectiveness, factors, marine protected areas, outcomes, shark and ray conservation, success
Aim
Concurrently, assessing the effectiveness of marine protected areas and evaluating the degree of risk from humans to key species provide valuable information that can be integrated into conservation management planning. Tiger sharks ( Galeocerdo cuvier ) are a wide‐ranging ecologically important species subject to various threats. The aim of this study was to identify “hotspots” of tiger shark habitat use in relation to protected areas and potential risks from fishing.
Location
Southwest Indian Ocean, east coast of South Africa and Mozambique.
Methods
Satellite tags were fitted to 26 tiger sharks. A subset of 19 sharks with an average period at liberty of 197 ( SD = 110) days were analysed using hotspot analysis to identify areas of core habitat use. The spatial and temporal overlap of significant hotspots with current and planned marine protected areas as well as risks from fishing and culling was then calculated.
Results
There was a 5.97% spatial overlap between tiger shark hotspots and marine protected areas, which would increase significantly ( p < .05) to 24.36% with the expansion of planned protected areas in South Africa and could be as high as 41.43% if Mozambique similarly expanded neighbouring protected area boundaries. Tiger sharks remained largely coastal, but only showed a spatial overlap of 5.12% with shark culling nets in South Africa. Only three sharks undertook open ocean migrations during which they were more likely to interact with longline fisheries in the region.
Main conclusions
This study demonstrates how spatial information can be used to assess the overlap between marine protected areas and the core habitats of top marine predators and highlights how congruent transnational conservation management can improve the effectiveness of protected areas. Core habitat use of marine apex predators may also be indicative of productive habitats, and therefore, predators such as tiger sharks could act as surrogate species for identifying key habitats to prioritize for conservation planning.
Marine reserves are a commonly applied conservation tool, but their size is often chosen based on considerations of socio-economic rather than ecological impact. Here, we use a simple individual-based model together with the latest empirical information on home ranges and densities in 66 coral reef fishes to quantify the conservation effectiveness of various reserve sizes. We find that standard reserves with a diameter of 1–2 km can achieve partial protection (≥50% of the maximum number of individuals) of 56% of all simulated species. Partial protection of the most important fishery species, and of species with diverse functional roles, required 2–10 km wide reserves. Full protection of nearly all simulated species required 100 km wide reserves. Linear regressions based on the mean home range and density, and even just the maximum length, of fish species approximated these results reliably, and can therefore be used to support locally effective decision making. This article is protected by copyright. All rights reserved
AimUnderstanding the spatial and temporal variation in the distribution of migratory species is critical for management and conservation efforts. However, challenges in observing mobile marine species throughout their migratory pathways can impede the identification of critical habitat, linkages between these habitats and threat-mitigation strategies. This study aimed to gain insight into the long-term residency and movement patterns of the whale shark (Rhincodon typus) and to reveal important habitat in the context of R.typus usage of existing Marine Protected Areas (MPAs). LocationSouth-eastern Indian Ocean. Methods
Satellite telemetry was used to remotely track the long-term movements of 29 R.typus, and to quantify shark usage of the existing MPA network. From the tracking data and environmental predictors, nonlinear models were developed to predict suitable R.typus habitat throughout the south-eastern Indian Ocean. ResultsThis study includes the first documented complete return migrations by R.typus to Ningaloo Marine Park, which was found to be an important area for R.typus all year-round. We found that while existing MPAs along Australia's west coast do afford some protection to R.typus, telemetry-based habitat models revealed large areas of suitable habitat not currently protected, particularly along the Western Australian coast, in the Timor Sea, and in Indonesian and international waters. Main conclusionsAnimal-borne telemetric devices allowed the gathering of long-term spatial information from the elusive and highly mobile R.typus, revealing the spatial scale of their migration in the south-eastern Indian Ocean. Suitable habitat was predicted to occur inside conservation areas, but our findings indicate that the current MPA network may not sufficiently protect R.typus throughout the year. We suggest that telemetry-based habitat models can be an important tool to inform conservation planning and spatial management efforts for migratory species.
Marine reserves, areas protected from ex ploitative anthropogenic processes, are being widely implemented to conserve biodiversity and initiate species recovery. Evidence supports the effectiveness of marine reserves in improving biological attributes such as biodiversity, density, biomass, and body-size for sedentary species or those with r-selected life histories. However, there is limited long-term time series- based information determining the effectiveness of these protected areas for elasmobranchs. Marine reserve effectiveness is commonly evaluated spatially by examining differences in species' biological parameters inside and outside of protective boundaries, which can often mask the occurrence of slow population declines. We used a temporal fishery-independent standardized longline survey at Glover's Reef Mar - ine Reserve, Belize, to monitor long-term population trends in the commercially important Caribbean reef shark Carcharhinus perezi for more than a decade. Linear models were performed to examine whether the factors habitat, year, or their interaction had a significant impact on C. perezi catch per unit effort (CPUE) and on catch demographic composition. Only the factor 'habitat' had a significant influence on CPUE, with the forereef catch significantly higher than in the lagoon. Our results support that the population of Caribbean reef shark at Glover's Reef Marine Reserve appears stable with no significant decline in CPUE or decrease in mean total length detected. This is evidence that marine reserves can be an effective conservation tool for reef-associated shark species.
One goal of global marine protected areas (MPAs) is to ensure they represent a breadth of taxonomic biodiversity. Ensuring representation of species in MPAs, however, would require protecting vast areas of the global oceans and does not explicitly prioritize species of conservation concern. When threatened species are considered, a recent study found that only a small fraction of their geographic ranges are within the global MPA network. Which global marine areas, and what conservation actions beyond MPAs could be prioritized to prevent marine extinctions (Convention on Biological Diversity Aichi Target 12), remains unknown. Here, we use systematic conservation planning approaches to prioritize conservation actions for sharks, rays and chimaeras (class Chondrichthyes). We use chondrichthyans as they have the highest proportion of threatened species of any marine class. We find that expanding the MPA network by 3% in 70 nations would cover half of the geographic range of 99 imperilled endemic chondrichthyans. Our hotspot analysis reveals that just 12 nations harbour more than half (53) of the imperilled endemics. Four of these hotspot nations are within the top ten chondrichthyan fishing nations in the world, but are yet to implement basic chondrichthyan fisheries management. Given their geopolitical realities, conservation action for some countries will require relief and reorganization to enable sustainable fisheries and species protection.
Background
Protected areas, regarded today as a cornerstone of nature conservation, result from an array of multiple motivations and opportunities. We explored at global and regional levels the current distribution of protected areas along biophysical, human, and biological gradients, and assessed to what extent protection has pursued (i) a balanced representation of biophysical environments, (ii) a set of preferred conditions (biological, spiritual, economic, or geopolitical), or (iii) existing opportunities for conservation regardless of any representation or preference criteria.
Methods
We used histograms to describe the distribution of terrestrial protected areas along biophysical, human, and biological independent gradients and linear and non-linear regression and correlation analyses to describe the sign, shape, and strength of the relationships. We used a random forest analysis to rank the importance of different variables related to conservation preferences and opportunity drivers, and an evenness metric to quantify representativeness.
Results
We find that protection at a global level is primarily driven by the opportunities provided by isolation and a low population density (variable importance = 34.6 and 19.9, respectively). Preferences play a secondary role, with a bias towards tourism attractiveness and proximity to international borders (variable importance = 12.7 and 3.4, respectively). Opportunities shape protection strongly in “North America & Australia–NZ” and “Latin America & Caribbean,” while the importance of the representativeness of biophysical environments is higher in “Sub-Saharan Africa” (1.3 times the average of other regions).
Discussion
Environmental representativeness and biodiversity protection are top priorities in land conservation agendas. However, our results suggest that they have been minor players driving current protection at both global and regional levels. Attempts to increase their relevance will necessarily have to recognize the predominant opportunistic nature that the establishment of protected areas has had until present times.
Baited Remote Underwater Video Stations (BRUVS) is a popular technique to assess mobile nektonic and demersal assemblages, particularly for fish communities. The benefits of using BRUVS have been well documented, with their non-destructive and non-extractive nature, ease to replicate, relatively-cheap personnel costs, and low risk to personnel often cited. However, there is a wide variability in the set-up, experimental design, and implementation of this method. We performed a literature review of 161 peer-reviewed studies from all continents published from 1950 to 2016 to describe how BRUVS has been used by quantitatively assessing 24 variables, including camera set-up and orientation, soak time, bait quantity, type and preparation method, habitat and depth deployed in, and number of replicates used. Such information is critical to gauge the comparability of the results obtained across BRUVS studies. Generally, there was a wide variety in the location, deployment method, bait used, and for the purpose that BRUVS was deployed. In some studies, the methods were adequately described so that they included information on the 24 variables analysed, but there were 34 % of studies which failed to report three or more variables. We present a protocol for what minimal information to include in methods sections and urge authors to include all relevant information to ensure replicability and allow adequate comparisons to be made across studies.
Summary and Analysis of Extension Program Evaluation in R
2016. Salvatore Mangiafico. Rutgers Cooperative Extension. 569 pages.
Statistical analyses in R for extension program education. Descriptive statistics, plots, confidence intervals, hypothesis testing, Likert data, nonparametric tests, permutation tests, ordinal regression, tests for nominal data, analysis of variance, count data. Least square means, random effects, mixed models. Plus appearances by my favorite cartoon characters.
Web: http://rcompanion.org/handbook. Pdf: http://rcompanion.org/documents/RHandbookProgramEvaluation.pdf.
Global declines in chondrichthyan populations necessitate evidence‑based planning for their conservation. False Bay, in south‑west South Africa, has a high diversity of marine biota, with Atlantic and Indian Ocean influences, but its chondrichthyan fauna is poorly described ecologically. False Bay has a long fishing history and supports various harvesting methods, including shark‑directed fishing. This is the first baited remote underwater video system (BRUVs) survey of the relative abundance, diversity and seasonal distribution of chondrichthyans in False Bay. Nineteen species from 11 families were recorded across 185 sites at between 4 and 49 m depth. Diversity was greatest in summer, on reefs and in shallow water. Endemic scyliorhinids, especially Haploblepharus edwardsii, dominated everywhere, in summer and winter. Habitat and season were key predictors of species composition, and a significant interaction between depth and season indicated migration patterns for Mustelus mustelus. By avoiding the selectivity associated with catch records, BRUVs data are superior to fishery‑dependent catch‑per‑unit‑effort data to monitor chondrichthyan diversity and abundance. Baited remote underwater video systems access greater depths and more habitats than previously surveyed in False Bay and avoid taxonomic lumping typical of catch records in the region, making them more efficient than other methods of surveying chondrichthyan diversity.
Chondrichthyans (sharks, skates, rays and chimaeras) are captured in many marine fisheries. Management and research efforts directed at chondrichthyan fishing are often neglected because of low product value, taxonomic uncertainty, low capture rates, and harvesting by multiple fisheries. In South Africa's diverse fishery sectors, which include artisanal as well as highly industrialised fisheries, 99 (49%) of 204 chondrichthyan species that occur in southern Africa are targeted regularly or taken as bycatch. Total reported dressed catch for 2010, 2011 and 2012 was estimated to be 3 375 t, 3 241 t and 2 527 t, respectively. Two‑thirds of the reported catch was bycatch. Regulations aimed at limiting chondrichthyan catches, coupled with species‑specific permit conditions, currently exist in the following fisheries: demersal shark longline, pelagic longline, recreational line, and beach‑seine and gillnet. Limited management measures are currently in place for chondrichthyans captured in other South African fisheries. Catch and effort dataseries suitable for stock assessments exist for fewer than 10 species. Stock assessments have been attempted for five shark species: soupfin Galeorhinus galeus, smoothhound Mustelus mustelus, white Carcharodon carcharias, spotted ragged‑tooth Carcharias taurus, and spotted gully Triakis megalopterus. Fishery‑independent surveys and fishery observer data, which can be used as a measure of relative abundance, exist for 67 species. Compared with most developing countries, South African shark fishing is relatively well controlled and managed. As elsewhere, incidental capture and bycatch remain challenges to the appropriate management of shark species. In 2013, South Africa's National Plan of Action for the Conservation and Management of Sharks (NPOA‑Sharks) was published. Implementation of the NPOA‑Sharks should help to improve chondrichthyan management in the near future.
Well-designed and effectively managed networks of marine reserves can be effective tools for both fisheries management and biodiversity conservation. Connectivity, the demographic linking of local populations through the dispersal of individuals as larvae, juveniles or adults, is a key ecological factor to consider in marine reserve design, since it has important implications for the persistence of metapopulations and their recovery from disturbance. For marine reserves to protect biodiversity and enhance populations of species in fished areas, they must be able to sustain focal species (particularly fishery species) within their boundaries, and be spaced such that they can function as mutually replenishing networks whilst providing recruitment subsidies to fished areas. Thus the configuration (size, spacing and location) of individual reserves within a network should be informed by larval dispersal and movement patterns of the species for which protection is required. In the past, empirical data regarding larval dispersal and movement patterns of adults and juveniles of many tropical marine species have been unavailable or inaccessible to practitioners responsible for marine reserve design. Recent empirical studies using new technologies have also provided fresh insights into movement patterns of many species and redefined our understanding of connectivity among populations through larval dispersal. Our review of movement patterns of 34 families (210 species) of coral reef fishes demonstrates that movement patterns (home ranges, ontogenetic shifts and spawning migrations) vary among and within species, and are influenced by a range of factors (e.g. size, sex, behaviour, density, habitat characteristics, season, tide and time of day). Some species move <0.1–0.5 km (e.g. damselfishes, butterflyfishes and angelfishes), <0.5–3 km (e.g. most parrotfishes, goatfishes and surgeonfishes) or 3–10 km (e.g. large parrotfishes and wrasses), while others move tens to hundreds (e.g. some groupers, emperors, snappers and jacks) or thousands of kilometres (e.g. some sharks and tuna). Larval dispersal distances tend to be <5–15 km, and self-recruitment is common. Synthesising this information allows us, for the first time, to provide species, specific advice on the size, spacing and location of marine reserves in tropical marine ecosystems to maximise benefits for conservation and fisheries management for a range of taxa. We recommend that: (i) marine reserves should be more than twice the size of the home range of focal species (in all directions), thus marine reserves of various sizes will be required depending on which species require protection, how far they move, and if other effective protection is in place outside reserves; (ii) reserve spacing should be <15 km, with smaller reserves spaced more closely; and (iii) marine reserves should include habitats that are critical to the life history of focal species (e.g. home ranges, nursery grounds, migration corridors and spawning aggregations), and be located to accommodate movement patterns among these. We also provide practical advice for practitioners on how to use this information to design, evaluate and monitor the effectiveness of marine reserve networks within broader ecological, socioeconomic and management contexts.
Estimates of the relative density of fishes
form the basis of many marine ecological studies as well as the assessment of
effects of fishing or pollution. Plasticity in the behavioural response of
large reef fishes to SCUBA divers means that commonly used underwater visual
census (UVC) techniques do not always provide reliable estimates of relative
density. The paper describes the system configuration, deployment methods,
testing and use of a remotely deployed baited underwater video (BUV) system
for the survey of carnivorous reef fishes (snapper,
Pagrus auratus and blue
cod,Parapercis colias) in marine reserves of northern
New Zealand. Concurrent UVC and BUV surveys inside and outside a marine
reserve showed that, whereas UVC detected few snapper in either area
(resulting in little confidence in statistically significant results), BUV
demonstrated significant differences in relative density. Conversely, blue cod
were found to occur at significantly higher densities within the reserve by
UVC, but not by BUV. The provision of accurate estimates of fish size (<20
mm error) from video footage also illustrated differences in size structure
between protected and fished populations. The data suggest that a combination
of survey techniques is likely to be necessary where multispecies assemblages
are being assessed.
Marine protected areas (MPAs) play an important role in coastal conservation, but there is presently no uniformly applied methodology for monitoring the efficacy of coastal fish protection. Whereas underwater visual census and controlled angling surveys have been used, their skilled-labour requirements and environmental impact have prevented their nation-wide application in South Africa. We used a baited remote underwater video system (BRUVs) to provide the first survey of reef fishes in the Stilbaai MPA (SMPA), and assessed the deployment time and sample size requirements of BRUVs for reef fish monitoring. Thirty-eight species, including 13 chondrichthyans, were recorded in one-hour deployments across 29 sites in the 11.3 km2 no-take zone of the SMPA, in depths ranging from 5 to 41 m. Bait was limited to sardine Sardinops sagax homogenate, but the species recorded by BRUVs comprised several feeding guilds, including herbivores. Optimal deployment time was 49 min, but 60 min is recommended as a conservative and practical standard. Over a five-year period, annual BRUVs sample sizes required to detect increases in abundance of 0.1 y−1 with 80% power would be 28 deployments for abundant species and 129 for rare species. Detection of decreases of equivalent magnitude will require more samples.
National and international policies have encouraged the establishment of a representative network of marine protected areas (MPAs) in South Africa, with the aim of protecting marine biodiversity. The extent to which these marine and estuarine protected areas (EPAs) represent marine fish species and communities was assessed by comparing their species compositions with those of exploited areas, as sampled using four fishing techniques. Seven hundred fish species were sampled, representing one-third of South Africa's marine fishes. MPAs in coastal habitats scored c. 40% on the Bray-Curtis measure of similarity for species representativeness, but this score declined markedly for offshore ‘trawlable’ fishing grounds. The combined effects of sampling error, temporal variation and the effects of fishing on relative abundance suggest that 80% similarity would be the maximum achieveable. Forty-nine per cent of all fish species that were recorded were found in the 14 MPAs sampled. Redundancy in the MPA network was low, with fish species most commonly being represented in only one MPA or absent. There was greater redundancy in the 33 EPAs, with 40% of species being found in two or more EPAs, but many of these estuaries were adjacent to each other and embedded in large MPAs. Deep water fish communities (>80 m deep) and communities located on the west and south-east coasts of South Africa were most poorly represented by MPAs. Routine fishery surveys provide a robust and repeatable opportunity to assess species representativeness in MPAs, and the method used could form the basis of an operational definition of ‘representative’. In contrast to an assessment based on presence-absence data, this analysis of quantitative data presents a more pessimistic assessment of protection.
Counts of growth bands in sectioned vertebral centra were used to estimate the ages of 61 bronze whalers Carcharhinus brachyurus collected between March 1984 and June 1988 from southern Africa. Estimates of Von Bertalanffy parameters for the observed data were: L∞ = 384,8, K = 0,0385, t0 = −3,477. The t0 value overestimates the gestation, which is thought to be between 8 and 24 months. Growth in bronze whalers appears to be slower than in any Carcharhinus spp. previously studied. Maximum size recorded during this study was 294 cm total length (TL) for a male and 288 cm TL for a female, and the maximum ages recorded were 30 and 25 years respectively. Age at sexual maturity has been calculated at 13–19 years for males and 19–20 years for females. Differential mortality rates appear to operate on juveniles (Lee's phenomenon). Arguments are presented that indicate two separate populations: one distributed from the Western Cape eastwards and the other from just south of Walvis Bay northwards. The slow growth rate, low fecundity and high age at sexual maturity make the bronze whaler extremely vulnerable to overfishing.
Previous work on white sharks indicate the species show seasonally limited movement patters, at certain aggregation sites small areas may play vital roles in the life history of a large amount of the population. Acoustic telemetry was used to estimate habitat use of white sharks, Carcharodon carcharias, while aggregating at Mossel Bay, South Africa. Total range of all shark tracks combined accumulated 782 h and covered an area of 93.5 km2 however, within this range, sharks were found to highly utilise a core habitat (50 % Kernel, K50) of just 1.05 km2 over a reef system adjacent to a river mouth. Individual tracks revealed additional core habitats, some of which were previously undocumented and one adjacent to a commercial harbor. Much was found to be dependent on the size of the shark, with larger sharks (>400 cm) occupying smaller activity areas than subadult (300–399 cm) and juvenile (<300 cm) conspecifics, while Index of Reuse (IOR) and Index of Shared Space (IOSS) were both found to increase with shark size. Such results provide evidence that larger white sharks are more selective in habitat use, which indicates they have greater experience within aggregation sites. Furthermore, the focused nature of foraging means spatially restricted management strategies would offer a powerful tool to aid enforcement of current protective legislation for the white shark in similar environments of limited resources and capacity.
Anumber of demersal shark species are processed
in South Africa for export to Australia, where
there is high consumer demand for shark fillets
that cannot be met by Australia’s shark fishing industry.
Most of these sharks are caught as by-catch but some are
targeted in a number of South African fisheries. This
paper examines the harvest of demersal sharks in South
Africa, and the processing of demersal shark meat destined
for export to Australia. Trade statistics for demersal
shark products traded between the two countries during
the period 1998 to 2005 were reviewed. The study
shows that there is limited management and monitoring
of the catch and trade in these species and related products;
these inadequate regulatory controls, coupled with
the increased targeting of demersal sharks in the South
African traditional linefishery, could make certain
species vulnerable to over-harvesting. Further, there are
discrepancies in the import and export datasets for the
two countries, and both the catch figures and trade data
lack the necessary detail for effective monitoring and
regulation of the catch and trade. Capacity building of
compliance officers to improve identification of demersal
shark products in trade is required and trade data
discrepancies should be resolved. A review of trade categories
used by Australia and South Africa for shark
products in trade would assist in monitoring the trade.
No-take marine protected areas (MPAs) are a commonly applied tool to reduce human fishing impacts on marine and coastal ecosystems. However, conservation outcomes of MPAs for mobile and long-lived predators such as sharks are highly variable. Here, we use empirical animal tracking data from 459 individual sharks and baited remote underwater video surveys undertaken in 36 countries to construct an empirically supported individual-based model that estimates the conservation effectiveness of MPAs for five species of coral reef-associated sharks (Triaenodon obesus, Carcharhinus melanopterus, Carcharhinus amblyrhynchos, Carcharhinus perezi, and Ginglymostoma cirratum). We demonstrate how species-specific individual movement traits can contribute to fishing mortality of sharks found within MPAs as they move outside to adjacent fishing grounds. We discovered that the world's officially recorded coral reef-based managed areas (with a median width of 9.4 km) would need to be enforced as strict no-take MPAs and up to 5 times larger to expect protection of the majority of individuals of the five investigated reef shark species. The magnitude of this effect depended on local abundances and fishing pressure, with MPAs required to be 1.6-2.6 times larger to protect the same number of Atlantic and Caribbean species, which occur at lower abundances than similar species in the western Pacific. Furthermore, our model was used to quantify partially substantial reductions (>50%) in fishing mortality resulting from small increases in MPA size, allowing us to bridge a critical gap between traditional conservation planning and fisheries management. Overall, our results highlight the challenge of relying on abundance data alone to ensure that estimates of shark conservation impacts of MPAs follow the precautionary approach.
Mangroves provide essential habitat for juvenile fish species. Restoration and monitoring are important conservation tools to ensure the recovery and maintenance of coastal mangrove habitats impacted by humans. In this study, Baited Remote Underwater Video Stations (BRVUS) were used to non-invasively examine the relative abundance and richness of fishes within restored mangrove pools in Biscayne Bay, Florida, 15 years after replanting. The potential influence of several environmental factors on fish abundance and richness within the restored mangrove pools was also evaluated. Limited seine sampling was also conducted to provide a comparison of the current fish assemblage with that of two prior surveys using seine nets. Twenty fish taxa were observed in the current study, consisting of five families, two genera, and thirteen species. Several environmental factors emerged as significant influences on the presence and abundance of different fish taxa, especially individual pools. A comparison of CPUE between current and prior seine studies found an increase in forage fish taxa and a shift from taxa that prefer a range of habitats to mangrove specific taxa, indicating an increased ecological function of these mangroves as fish habitat.
There is limited evidence on the rate at which the shark populations of coral reefs can rebound from over-exploitation, the baselines that might signify when recovery has occurred and the role of no-take Marine Protected Areas (MPA) in aiding this process. We surveyed shark assemblages at Ashmore Reef in Western Australia using baited remote underwater video stations in 2004 prior to enforcement of MPA status and then again in 2016 after eight years of strict enforcement. We found an increase in the relative mean abundance of Carcharhinus amblyrhynchos from 0.16 ± 0.06 individuals h−1 in 2004 to 0.74 ± 0.11 individuals h−1 in 2016, a change that was also accompanied by a shift in the assemblage of sharks to greater proportions of apex species (from 7.1% to 11.9%) and reef sharks (from 28.6% to 57.6%), and a decrease in the proportional abundance of lower trophic level species (from 64.3% to 30.5%). Abundances and trophic assemblage of sharks at Ashmore Reef in 2004 resembled those of the Scott Reefs, where targeted fishing for sharks still occurs, whereas in 2016, abundances and trophic structures had recovered to resemble those of the Rowley Shoals, a reef system that has been a strictly enforced MPA for over 25 years. The shift in abundance and community structure coincident with strict enforcement of the MPA at Ashmore Reef has occurred at a rate greater than predicted by demographic models, implying the action of compensatory processes in recovery. Our study shows that shark communities can recover rapidly after exploitation in a well-managed no-take MPA.
Evidence from the wild as to the ecological and evolutionary consequences of top predator depletions remains limited, especially in marine systems. Given the pace and extent of predator loss, an understanding of these processes is important. Two sets of adjacent coral reef systems off north-western Australia have similar biological, physical and environmental conditions, but one of the reef systems has been exposed to nearly exclusive commercial fishing of sharks. Across reefs where sharks have been depleted, prey fishes had significantly smaller caudal fins and eyes compared to the reefs with intact shark populations (up to 40 and 46% relative difference in standardized means). These patterns were consistent across 7 teleost prey species (N = 611 individuals) that vary in behavior, diet and trophic guild. We hypothesize that these morphological patterns were primarily driven by differences in shark predation. Morphological differences were not consistent with plausible alternative explanations (habitat complexity, temperature, light, current, food availability, prey targets, competition) as primary drivers. These results provide field evidence of morphological changes in prey potentially due to predator depletions consistent with ecological predictions; specifically, predator loss caused a reduction in the size of prey morphological traits associated with predator detection and evasion. While our analysis cannot differentiate between rapid evolutionary change versus morphological plasticity due to shark depletions, either possible outcome would indicate that predator removals may have profound effects on body shapes of prey communities. This is particularly significant in the case of sharks, given that the consequences of their widespread removal have been a topic of significant speculation, debate and concern.
Sharks, rays, and chimaeras (Class Chondrichthyes; herein ‘sharks’) are the earliest extant jawed vertebrates and exhibit some of the greatest functional diversity of all vertebrates. Ecologically, they influence energy transfer vertically through trophic levels and sometimes trophic cascades via direct consumption and predation risk. Through movements and migrations, they connect horizontally and temporally across habitats and ecosystems, integrating energy flows at large spatial scales and across time. This connectivity flows from ontogenetic growth in size and spatial movements, which in turn underpins their relatively low reproductive rates compared with other exploited ocean fishes. Sharks are also ecologically and demographically diverse and are taken in a wide variety of fisheries for multiple products (e.g. meat, fins, teeth, and gills). Consequently, a range of fisheries management measures are generally preferable to ‘silver bullet’ and ‘one size fits all’ conservation actions. Some species with extremely low annual reproductive output can easily become endangered and hence require strict protections to minimize mortality. Other, more prolific species can withstand fishing over the long term if catches are subject to effective catch limits throughout the species’ range. We identify, based on the IUCN Red List status, 64 endangered species in particular need of new or stricter protections and 514 species in need of improvements to fisheries management. We designate priority countries for such actions, recognizing the widely differing fishing pressures and conservation capacity. We hope that this analysis assists efforts to ensure this group of ecologically important and evolutionarily distinct animals can support both ocean ecosystems and human activities in the future.
The design of ecological networks of marine protected areas (MPAs) is generally based on the identification of areas of high abundance for species of conservation concern or focal biodiversity targets. We discuss the applicability of this approach to marine top predators and contend that the design of comprehensive and effective MPA networks requires the following 7 principles: (1) the use of wildlife-habitat modelling and spatial mapping approaches to develop testable model predictions of species distribution and abundance; (2) the incorporation of life-history and behavioural data into the development of these predictive habitat models; (3) the explicit assessment of threats in the design and monitoring process for single- or multi-species MPAs; (4) the serious consideration of dynamic MPA designs to encompass species which use well-defined but spatially dynamic ocean features; (5) the integration of demographic assessment in MPA planning, allowing provision of advice to policy makers, ranging from no to full protection; (6) the clear articulation of management and monitoring plans allowing retrospective evaluation of MPA effectiveness; and (7) the adoption of an adaptive management approach, essential in the light of ongoing and anticipated ecosystem changes and species range shifts in response to climate change.
To provide more information about whether sharks benefit from no-take marine reserves, we quantified the relative abundance and biomass of reef sharks inside and outside of Namena, Fiji’s largest reserve (60.6 km2). Using stereo baited remote underwater video systems (stereo-BRUVs), we found that the abundance and biomass of sharks was approximately two and four times greater in shallow and deep locations, respectively, within the Namena reserve compared to adjacent fished areas. The greater abundance and biomass of reef sharks inside Namena is likely a result of greater prey availability rather than protection from fishing. This study demonstrates that marine reserves can benefit sharks.
Sharks have been shown to benefit from the protection of marine protected areas (MPAs). There is, however, little
information on the degree of protection by MPAs to shark populations. The movements of individual smoothhound
sharks Mustelus mustelus in, and adjacent to, a small (34 km2) no-take MPA (Langebaan Lagoon Marine Protected
Area; LMPA) situated on the west coast of South Africa were investigated over two years using acoustic telemetry.
Sharks spent the majority of the time (in hours, average 79%) inside the reserve, and some sharks (n = 2 of 15
recorded during a full year) did not leave the reserve during the study period. Time spent inside the LMPA and the
number of crossings of its boundary were strongly influenced by season. Sharks concentrated inside the LMPA
during summer, whereas they were widely distributed throughout the study area during winter. Six sharks left
the Saldanha Bay embayment during spring and winter for durations ranging from two to 156 days (median = 111
days). All returned to the bay within the study period. Individuals recorded over two years showed consistency in
behavioural patterns and protection by the LMPA between years, and spent an average of 74% and 80% of the time
inside the LMPA during the two study years respectively. The extended residency of smoothhound sharks within
the LMPA suggests that no-take area protection may be a viable management option.te or up to date.