Article

Use of total allowable catch to regulate a selective marine aquarium fishery

Authors:
  • PNG National Fisheries Authority
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Abstract

The Papua New Guinea (PNG) marine aquarium fishery was partly managed by total allowable catch (TAC) limits, implemented since the fishery's inception in 2008. Species-specific TACs, based on stock assessments conducted prior to the commencement of fishing, were established for all fish and invertebrate species presumed to be fished by the fishery. By analysing the selectivity of the PNG fishery in 2012, a large portion (74.9%) of the managed fish diversity (n = 267 species) was found to be “weakly” to “strongly” avoided relative to their availability. More than half (53.2%; n = 142) of the fish species with TACs were never fished in 2012. Of those species with TACs that were actually fished, 76.8% (n = 96) of fish and all invertebrate catches never exceeded 1% of their TACs. Catches of only seven fish species exceeded 10% of their TACs. Catch records also identified 124 fish species that were fished in the absence of species-specific TACs. Unbiased recursive partitioning was used to examine ecological attributes of these species to help identify flaws in the methods used for initial TAC assignment. Refining the role species-specific TACs play in the management of this fishery is necessary to optimise managerial resources. The lessons learned from this approach to marine aquarium fishery management are likely to be of interest and value to PNG, other developing island nations, and marine aquarium fisheries globally.

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... Price premiums also reflect perceived rarity and thus can drive markets for collection in the wild (Rhyne et al. 2012b). A study by Militz et al. (2018a) in Papua New Guinea found that collectors and exporters received export prices that were exponentially related to the rarity of two different color morphs of two anemonefish species, A. perculua (grey circles) and A. biaculeatus (black circles) color morphs. Even with the increase in economic value of individual morphs, they did not find that overexploitation of the fishery as fishers collected more opportunistically rather than focusing the time needed to find the rare morphs. ...
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A frequent expectation of the use of marine reserves in management of coral reef fisheries is maintenance or enhancement of yields to areas adjacent to reserves by adult (post-settlement) movements from reserve to fished areas (the so-called 'spillover effect'). Demonstration of this effect has been rare. This paper reports on some circumstantial evidence derived from underwater visual census monitoring of densities of large predatory coral reef fish [Serranidae (Epinephelinae), Lutjanidae, Lethrinidae and Carangidae as a group] inside and adjacent to a small marine reserve at Apo Island in the central Philippines over a 10 yr period (1983 to 1993). The marine reserve (sanctuary) at Apo Island was established in 1982 and was protected from fishing for the duration of the study. The non-reserve area was open to fishing by up to 200 municipal fishers using traditional fishing gear (bamboo traps, hooks and lines, gill nets and spears). Significant positive correlations of both mean density and species richness of large predatory fish with duration of reserve protection (from 1 to 11 yr) were observed in both the reserve and non-reserve areas surveyed. The minimum distance from the boundary of the reserve to the non-reserve area surveyed was 200 m. During the first 8 yr of reserve protection combined, the density of large predatory fish at distances 200 to 300, 300 to 400 and 400 to 500 m from the reserve boundary did not differ significantly from an even distribution (chi-squared test, p > 0.05). During the period of 9 to 11 yr of protection combined, there was a significantly higher density of these fish in the area closest to the reserve (i.e. in the 200 to 300 m area, chi-squared test, p < 0.05). This visual census data is consistent with a proposed model of adult fish export from the reserve to the non-reserve areas. Along with interview data collected in 1986 and 1992 that showed that fishers were unanimous that their yields had increased since the reserve was implemented, this study provides evidence for export of adult fish from reserve to fished areas.
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Since the 1970s, people in Melanesian countries have been beguiled by the prospect of economic development that would enable them to participate in a world market economic system and so allow them to progress, to improve their standards of living and to take their places as independent nations in a modern world. The forms of participation available to them and those encouraged by international capital entailed the extraction of natural resources - minerals, timber and fish. In these enterprises, the 'developers' provided the capital and the Melanesians provided the resources and sometimes the cheap labor. These projects were also viewed as ways of supporting emergent independent national governments through equity agreements, taxes and royalties. 'Development' referred to both the economic and the political processes facilitated by resource extraction by multinational corporations. Globalization, like 'development,' is a loose term that describes or theorizes the processes whereby economic activities in these small islands are constituted within a broad financial and political landscape that is shaped by the distant, 'developed' nations and their linked corporations. It encompasses the financial, economic and political policies and practices of this imagined entity - the 'global economy' - and incorporates the communication made possible through electronic media. But 'globalization' also includes the emergence of 'global culture' and the dissemination of knowledge, ideas and desires. As with the economic imperatives, the cultural forces originate predominantly in
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Atlantic cod (Gadus morhua) was the dominant demersal fish and most important predator in the southern Gulf of St. Lawrence ecosystem as recently as the 1980s. However, productivity of southern Gulf cod has declined, and the population is no longer viable even in the absence of fishing. We conducted population projections taking into account uncertainty in current abundance-at-age and uncertainty or variability in each of the components of population productivity (i.e., rates of recruitment, individual growth, and adult natural mortality). We defined extirpation as a spawning stock biomass less than 1000 t (< 0.3% of historical levels). Based on these projections, at its current level of productivity, this population is certain to be extirpated within 40 years in the absence of fishing and in 20 years with fishery removals at the level of the total allowable catch in 2007 and 2008 (2000 t). Elevated natural mortality of adult cod (M) is the main factor contributing to the low productivity of this stock. Because M appears to be increasing, our projections are likely overly optimistic.
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Marine protected areas can enhance fish stocks within their boundaries, but the circumstances in which they might also supplement stocks or enhance fisheries outside their boundaries are less clear. Using visual survey and fishery data, we assess the impacts of increasing fishing effort, and of the establishment in Hawaii of a network of areas closed to aquarium fishing, on the prime-target species, yellow tang (Zebrasoma flavescens), and draw conclusions about MPA impacts on long-term fishery sustainability. Between 1999, when 27.8% of the coastline was closed to collecting, and 2007, the number of active fishers and total catch of yellow tang doubled. Prior to MPA establishment, yellow tang densities were similar at sites open to fishing and those slated for closure. By 2007, closed areas had five times the density of prime targeted sized fish (5–10 cm), and 48% higher density of adults than open areas. Densities of adults in 'boundary' areas (open areas <1 km from nearest MPA boundary) were significantly higher than in open areas far from MPA boundaries, which was indicative of spillover at that scale. Given the long lifespan of yellow tang (>40 years) relative to the duration of protection and the increasing intensity of fishing, the likelihood is that protected areas will become increasingly important sources for the adult fishes which will sustain stocks and the fishery over the longer term.
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The commercial fishery for coral reef fish for the aquarium trade has begun to change, at least in some parts of the world, from destructive methods such as cyanide and dynamite fishing to less-destructive methods such as hand-net fishing. However, data on the effects on wild populations of such relatively nondestructive methods is nonexistent. The Banggai cardinalfish ( Pterapogon kauderni ) is a paternal mouthbrooder living in groups of 2–200 individuals in the proximity of sea urchins ( Diadema setosum ). This fish has limited dispersal abilities because it lacks a pelagic larval phase, and it is believed to be endemic to the Banggai archipelago off the east coast of Sulawesi, Indonesia. Since its rediscovery in 1995, the Banggai cardinalfish has become a popular aquarium fish, and thousands have been exported—mainly to North America, Japan, and Europe. To study the effects of the aquarium trade fishery on wild populations of the Banggai cardinalfish, we performed a field study in which we quantified density, age distribution ( quantified as the ratio of numbers of juveniles to adults ) and habitat quality ( i.e., sea urchin density ) at eight sites in the Banggai archipelago. Through interviews with local fishers, we estimated the fishing pressure at each site and related this to data on fish density. We found a marginally significant negative effect of fishing pressure on density of fish and significant negative effects on group size in both sea urchins and fish. We did not find any effect of fishing on fish size structure. To our knowledge this is the first study to compare sites under different amounts of fishing pressure that has demonstrated the negative effects of the aquarium trade on wild populations of reef fish, despite the widespread use of relatively nondestructive fishing methods.
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Tropical marine ornamentals comprise an increasingly important fishery worldwide. Although the potential for overexploitation of marine ornamentals is great, few studies have addressed the population-level impacts of ornamental exploitation and few ornamental fisheries are managed. Analysis of catch records obtained from collectors over a four-month period in the vicinity of Cebu, Philippines, showed that anemonefish and anemones comprised close to 60% of the total catch. Underwater visual census surveys revealed that both anemone and anemonefish densities were significantly lower in exploited areas than in protected areas. The low density of anemones on exploited reefs accounted for over 80% of the reduced density of anemonefish at those sites. There were similar numbers of anemonefish per unit area of anemone in protected and exploited sites; however, biomass of anemonefish per unit area of anemone was lower in exploited areas. Reduction of anemone removals is recommended to support the sustainable harvest of anemonefish from this region.
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The diversity and density of small, benthic reef fishes were estimated using visual census and enclosed rotenone stations, Visual census Underestimated the number of species present and the density of common species by up to 91%. (C) 2001 The Fisheries Society of the British Isles.
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Despite its wide use in terrestrial ecology, distance sampling is as yet rarely used in underwater visual censuses. The present study attempts to compare density estimators based on distance sampling and on strip transects. Three stations with increasing densities of Chaetodontidae and Pomacanthidae were sampled twice by two divers of unequal experience, using two different transect types. A total of 96 transects and 2970 records of Chaetodontidae and Pomacanthidae were analysed. Nine estimators based on distance sampling were calculated and only the best fit (DT estimator) was kept for comparison with other estimators. These were either based on the average distance of the fish to the transect (AD estimator), or a 3-m- or 5 m-wide strip transect estimator (FW3 and FW5, respectively). There were no significant differences between the means found by DT, AD and FW3. Lower density estimates were given by FW5 in all cases. FW3 and FW5 did not detect several significant differences between stations which were otherwise detected by DT or AD. The number of transects needed to detect a significant difference between stations was four to ten times higher with FW3 or FW5 than with DT or AD. Diver experience was found to be a significant factor in density estimates. However, this factor was less important than the choice of the density estimator Transect type or the day of sampling had no consequence for the estimates. The distance distributions of fish were divided into three different patterns which may be explained by a combination of detectability function and a behavioural component. (C) 1999 Ifremer/Cnrs/Inra/Ird/Cemagref/Editions scientifiques et medicales Elsevier SAS.
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Visual census biomass estimates are compared with yields of three emperor (Lethrinidae) genera from shallow water fished reef habitats and we demonstrate that visual census can consistently underestimate the exploitable biomass of Lethrinus spp. (C) 1995 The Fisheries Society of the British Isles.
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Direct estimates of larval retention and connectivity are essential to understand the structure and dynamics of marine metapopulations, and optimize the size and spacing of reserves within networks of marine-protected areas (MPAs). For coral reef fishes, while there are some empirical estimates of self-recruitment at isolated populations, exchange among sub-populations has been rarely quantified. Here, we used microsatellite DNA markers and a likelihood-based parentage analysis to assess the relative magnitude of self-recruitment and exchange among eight geographically distinct sub-populations of the panda clownfish Amphiprion polymnus along 30 km of coastline near Port Moresby, Papua New Guinea. In addition, we used an assignment/exclusion test to identify immigrants arriving from genetically distinct sources. Overall, 82 per cent of the juveniles were immigrants while 18 per cent were progeny of parents genotyped in our focal metapopulation. Of the immigrants, only 6 per cent were likely to be genetically distinct from the focal metapopulation, suggesting most of the connectivity is among sub-populations from a rather homogeneous genetic pool. Of the 18 per cent that were progeny of known adults, two-thirds dispersed among the eight sub-populations and only one-third settled back into natal sub-populations. Comparison of our data with previous studies suggested that variation in dispersal distances is likely to be influenced by the geographical setting and spacing of sub-populations.
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Acceptance of marine protected areas (MPAs) as fishery and conservation tools has been hampered by lack of direct evidence that MPAs successfully seed unprotected areas with larvae of targeted species. For the first time, we present direct evidence of large-scale population connectivity within an existing and effective network of MPAs. A new parentage analysis identified four parent-offspring pairs from a large, exploited population of the coral-reef fish Zebrasoma flavescens in Hawai'i, revealing larval dispersal distances ranging from 15 to 184 km. In two cases, successful dispersal was from an MPA to unprotected sites. Given high adult abundances, the documentation of any parent-offspring pairs demonstrates that ecologically-relevant larval connectivity between reefs is substantial. All offspring settled at sites to the north of where they were spawned. Satellite altimetry and oceanographic models from relevant time periods indicated a cyclonic eddy that created prevailing northward currents between sites where parents and offspring were found. These findings empirically demonstrate the effectiveness of MPAs as useful conservation and management tools and further highlight the importance of coupling oceanographic, genetic, and ecological data to predict, validate and quantify larval connectivity among marine populations.
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A remote archipelago, Hawai'i, offers a plethora of sought after coastal and marine tourism experiences. The same unique marine fauna that draws tourists also makes Hawai'i a major player in the international ornamental aquarium trade. For many residents of Hawai'i, the marine realm is part of their island home and interactions with tourists and tourism activities are a part of everyday life. For many residents, the ocean is an important resource and for some a staple source of livelihood, be it through tourism, fisheries, or the aquarium trade. This variance between extractive and non-extractive marine resource use creates conflicts between stakeholder groups in Hawai'i. This study thematically analyzes public testimony records, which included 1652 individual testimonies, from proposed legislation aimed to establish ‘an aquatic life conservation program in the Division of Aquatic Resources to implement conservation measures, including limited entry areas and certification requirements, to regulate the collection of fish and other aquatic life for aquarium purposes. Public opinions evident in individual testimonies are representative of the disagreement in the literature regarding the stability and health of reef fishes populations in Hawai'i and broader resource-user conflicts. This study aims to better describe the user conflict between stakeholder groups in the marine resources of Hawai'i by exposing themes concerning change in natural environments.
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Spillover, the net export of adult fish, is one mechanism by which no-take marine reserves may eventually have a positive influence on adjacent fisheries. Although evidence for spillover has increased recently, mechanisms inducing movement of adult fish from reserve to fished areas are poorly understood. While density-dependent export is a reasonable expectation, given that density of fish targeted by fisheries should increase over time inside well-protected no-take reserves, no study to date has demonstrated development of the process. This study provides evidence consistent with density-dependent export of a planktivorous reef fish, Naso vlamingii, from a small no-take reserve (protected for 20 years) at Apo Island, Philippines. Mean density of N. vlamingii increased threefold inside the reserve between 1983 and 2003. Density approached an asymptote inside the reserve after 15-20 years of protection. Modal size in the reserve increased from 35 to 45 cm total length (TL) over 20 years of protection. In addition, both density and modal size increased outside the reserve close to (200-300 m), but not farther from (300-500 m), the reserve boundary over the 20 years of reserve protection. Movement of adult N. vlamingii across the boundaries of the reserve was rare. Aggressive interactions among adult N. vlamingii were significantly higher (by 3.7 times) inside than outside the reserve. This suggests that density-dependent interactions were more intense inside the reserve. When interacting adults differed in size, the larger individual usually chased away the smaller one. Furthermore, the mean size of adult fish captured by experimental fishing decreased from 35-cm TL 50-100 m outside the boundary, to 32-cm TL 250-300 m outside the boundary. This represents some of the best evidence available for density-dependent home-range relocation of fish from a no-take reserve.
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Poos, J. J., Bogaards, J. A., Quirijns, F. J., Gillis, D. M., and Rijnsdorp, A. D. 2010. Individual quotas, fishing effort allocation, and over-quota discarding in mixed fisheries. – ICES Journal of Marine Science, 67: 323–333. Many fisheries are managed by total allowable catches (TACs) and a substantial part by individual quotas. Such output management has not been successful in mixed fisheries when fishers continue to fish while discarding marketable fish. We analyse the effects of individual quotas on spatial and temporal effort allocation and over-quota discarding in a multispecies fishery. Using a spatially explicit dynamic-state variable model, the optimal fishing strategy of fishers constrained by annual individual quotas, facing uncertainty in catch rates, is studied. Individual fishers will move away from areas with high catches of the restricted quota species and, depending on the cost of fishing, will stop fishing in certain periods of the year. Individual vessels will discard marketable fish, but only after their individual quota for the species under consideration has been reached. These results are in line with observations on effort allocation and discarding of marketable fish, both over-quota discarding and highgrading, by the Dutch beam-trawl fleet. The models we present can be used to predict the outcomes of management and are therefore a useful tool for fisheries scientists and managers.
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Coral reefs support numerous ornamental fisheries, but there are concerns about stock sustainability due to the volume of animals caught. Such impacts are difficult to quantify and manage because fishery data are often lacking. Here, we suggest a framework that integrates several data-poor assessment and management methods in order to provide management guidance for fisheries that differ widely in the kinds and amounts of data available. First, a resource manager could assess the status of the ecosystem (using quantitative metrics where data are available and semi-quantitative risk assessment where they are not) and determine whether overall fishing mortality should be reduced. Next, productivity susceptibility analysis can be used to estimate vulnerability to fishing using basic information on life history and the nature of the fishery. Information on the relative degree of exploitation (e.g. export data or ratios of fish density inside and outside no-take marine reserves) is then combined with the vulnerability ranks to prioritize species for precautionary management and further analysis. For example, species that are both highly exploited and vulnerable are good candidates for precautionary reductions in allowable capture. Species that appear to be less vulnerable could be managed on a stock-specific basis to prevent over-exploitation of some species resulting from the use of aggregate catch limits. The framework could be applied to coral reef ornamental fisheries which typically lack landings, catch-per-unit-effort and age-size data to generate management guidance to reduce overfishing risk. We illustrate the application of this framework to an ornamental fishery in Indonesia.
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Export of aquarium-fish from the Maldives began in 1980 and in 1989 almost 54,000 marine fishes, worth approximately US$ 130,000, were exported. The collection of aquarium species is confined to a relatively small area around the capital island, Malé. Estimates of annual exports of 95 species were obtained by examining packing-lists held by Maldivian Customs. In parallel, the population densities of about 70 aquarium-fish species were estimated by visual assessment. Using a number of assumptions, potential (maximum sustainable) yields for 65 of these species — those for which export data were available — were estimated for the area (530 km ² ) within a 13-km radius (one hour's journey by local boat) of Malé. For 27 species there were some reasons for concern about the levels of exploitation, although only 12 of these species appeared to be ‘at risk’ in 1986 (the year of highest exploitation). If the assumptions made in estimating potential sustainable yields were valid, these 12 aquarium-fish species were being overexploited or exploited at levels close to maximum sustainable yields. Should the trade expand threefold, a further 12 species are considered to be potentially at risk of overexploitation. Two species of butterflyfish, Chaetodon meyeri and C. triangulum , which feed exclusively on coral polyps and generally die in captivity after a short time, were being exported in significant numbers. Both clownfishes ( Amphiprion spp.) and their host sea-anemones were being heavily exploited. Because of the symbiotic relationship between these fishes and their anemone homes, this group may be particularly susceptible to overexploitation. Damage to branching corals may result from the collection of specimens of Dascyllus aruanus , which shelter within them. With many thousands of individuals of this species being exported each year, this could represent considerable collateral coral damage. Although levels of exploitation of ‘cleaner wrasses’ ( Labroides bicolor and L. dimidiatus ) appear well below potentially sustainable ones, it is unclear whether the health of reef fishes might locally be adversely affected in heavily exploited areas. Monitoring and regulation of the aquarium-fish trade is discussed, together with the need for collection of catch statistics by those involved in the trade. The importance of regulation of collection techniques, of standards of facilities, and of satisfactory packaging of fish for export, is stressed. If more accurate estimates of sustainable yields are to be obtained, there needs to be monitoring of populations of key aquarium-fish species in designated collecting areas where exploitation levels are known. Until such estimates become available, the cautious approach adopted in the Maldives to estimate yields and set species-based quotas will, it is hoped, prevent local overexploitation.
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Connectivity, the demographic linking of local populations through the dispersal of individuals, is one of the most poorly understood processes in population dynamics, yet has profound implications for conservation and harvest strategies. For marine species with pelagic larvae, direct estimation of connectivity remains logistically challenging and has mostly been limited to single snapshots in time. Here, we document seasonal and interannual patterns of larval dispersal in a metapopulation of the coral reef fish Amphiprion polymnus. A 3-year record of larval trajectories within and among nine discrete local populations from an area of approximately 35 km was established by determining the natal origin of settled juveniles through DNA parentage analysis. We found that spatial patterns of both self-recruitment and connectivity were remarkably consistent over time, with a low level of self-recruitment at the scale of individual sites. Connectivity among sites was common and multidirectional in all years and was not significantly influenced by seasonal variability of predominant surface current directions. However, approximately 75% of the sampled juveniles could not be assigned to parents within the study area, indicating high levels of immigrations from sources outside the study area. The data support predictions that the magnitude and temporal stability of larval connectivity decreases significantly with increasing distance between subpopulations, but increases with the size of subpopulations. Given the considerable effort needed to directly measure larval exchange, the consistent patterns suggest snapshot parentage analyses can provide useful dispersal estimates to inform spatial management decisions.
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Individual transferable quota (ITQ) programmes have been incorporated into many marine fisheries management strategies for 30 years, but their implementation and utility remains controversial. This study provides an overview of the global status of ITQ programmes, the reasons they have been adopted and the changes in stock biomass after their implementation. Eighteen countries currently use ITQs to manage several hundred stocks of at least 249 species. ITQs were adopted in these countries for many reasons: overcapitalization, economic gains, safety concerns for fishers and political change. The implementation of ITQs does not translate into consistent changes in stock biomass. Improvements in 12 of 20 stocks after ITQs were introduced suggest that ITQs can be an effective component of fisheries management strategies, but eight of the stocks continued to decline after ITQs were introduced. This suggests that alternative or complementary measures are needed to sustain those fisheries, such as combining ITQs with more effective total allowable catches, better enforcement and monitoring, and implementing aspects of ecosystem-based fisheries management.
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Coral reefs worldwide are being degraded because of global warming (coral bleaching) and coastal development (sedimentation and eutrophication). Predicting the risk of species extinctions from this type of habitat degradation is one of the most challenging and urgent tasks facing ecologists. Habitat specialists are thought to be more prone to extinction than generalists; however, specialists may be more susceptible to extinction because (1) they are specialists per se, (2) they are less abundant than generalists, or (3) both. Here, I show that declines in coral abundance lead to corresponding declines in the abundance of coral-dwelling fishes, but with proportionally greater losses to specialists than generalists. In addition, specialists have smaller initial population sizes than generalists. Consequently, specialists face a dual risk of extinction because their already small populations decline more rapidly than those of generalists. Corresponding with this increased extinction risk, I describe the local extinction of one specialist species and the near-global extinction of another species. I conclude that habitat specialists will be the first species lost from coral reefs because their small populations suffer the most from human-induced disturbances.
Article
Spillover, the net export of adult fish, is one mechanism by which no-take marine reserves may eventually have a positive influence on adjacent fisheries. Although evidence for spillover has increased recently, mechanisms inducing movement of adult fish from reserve to fished areas are poorly understood. While density-dependent export is a reasonable expectation, given that density of fish targeted by fisheries should increase over time inside well-protected no-take reserves, no study to date has demonstrated development of the process. This study provides evidence consistent with density-dependent export of a planktivorous reef fish, Naso vlamingii, from a small no-take reserve (protected for 20 years) at Apo Island, Philippines. Mean density of N. vlamingii increased threefold inside the reserve between 1983 and 2003. Density approached an asymptote inside the reserve after 15–20 years of protection. Modal size in the reserve increased from 35 to 45 cm total length (TL) over 20 years of protection. In addition, both density and modal size increased outside the reserve close to (200–300 m), but not farther from (300–500 m), the reserve boundary over the 20 years of reserve protection. Movement of adult N. vlamingii across the boundaries of the reserve was rare. Aggressive interactions among adult N. vlamingii were significantly higher (by 3.7 times) inside than outside the reserve. This suggests that density-dependent interactions were more intense inside the reserve. When interacting adults differed in size, the larger individual usually chased away the smaller one. Furthermore, the mean size of adult fish captured by experimental fishing decreased from 35-cm TL 50– 100 m outside the boundary, to 32-cm TL 250–300 m outside the boundary. This represents some of the best evidence available for density-dependent home-range relocation of fish from a no-take reserve.
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Increasing attention is being paid to overfishing and the biological, economic, and social implications of persistent mismanagement of aquatic natural resources. In this chorus of concern, little attention is focused on sustainable fisheries, and the lessons to be learned from management systems that produce these successes. Although there is no one prescription for sustainability, a range of quota-based management tools have been used to eliminate the race for fish, increasing the incentives for long-term investment and efficiency. Variously referred to as fishing rights, tenure rights, or dedicated access privileges, quota-based fisheries confer a percentage (or quota) of the total allowable catch to named entities over some predetermined period, from short-term auction systems to intergenerational customary sea tenure. Whether a rights-based system stems from a traditional fishing rights system or has been recently introduced into modern commercial fisheries, achieving sustainability in the fishery is dependent on incentivizing the collective – from local communities to national fleets – to actively participate in self-regulation of the resource. Thus criticism of the approach often stems from the observation of the potential for cheating at the individual level (e.g., high grading, excessive discards), and the necessary exclusivity that accompanies any transition in management from open access to club membership. It is also worth noting that the resource in question – the fish – remain a public good, and as such, the public should be compensated – or at least not taxed – for their use. Thus the cost of fishery management, and the windfall profits of fishery conversion, should be shared. Rights-based management is not a silver bullet, and is probably not appropriate for all fisheries; however, the successes of the longline fisheries for Pacific halibut and sablefish in Alaska, the artisanal fisheries for loco in Chile and for spiny lobster in Mexico, and the Australian fisheries for Northern prawns and rock lobster, all clearly indicate that fishing rights should have a central place in the fisheries management toolbox.
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Estimates of reef fish densities made by divers visually censusing 5 m wide strip transects were compared with capture–resight estimates calculated independently using data on the resighting frequencies of fish marked with colour-coded tags. The difference in density estimates between methods varied between species but with patterns consistent at the three eastern Tasmanian sites studied. Densities of the two most abundant species, the wrasses Notolabrus tetricus and Notolabrus fucicola, showed good agreement between methods. By contrast, populations of the two monacanthids Meuschenia australis and Meuschenia freycineti were underestimated by an order of magnitude in strip transects relative to capture–resight, while populations of the open-water latrid Latridopsis forsteri were overestimated.
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This paper explores the nature of conflict and how institutional failure may be a primary cause of conflict over natural resources. Typologies for studying conflicts are reviewed and a typology specific to tropical fishery conflicts is proposed. Using data from three tropical fisheries, it shows how conflicts emerge and how they are managed.1 The paper concludes that local level management of conflict can be successful, but, without proactive support from higher levels of government the underlying causes of conflict are unlikely to be removed in the long term.
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The impact of the TAC and quota system, which is the corner stone of resource management and conservation policy of the Common Fisheries Policy (CFP), is evaluated. Particular attention is given to the situation of the North Sea demersal fisheries, in order to elucidate the effectiveness of the resource management. The TAC and quota system has not had the desired influence on the direction of economic development in the fishing industry. The system fails to achieve its principal aim, which is to maintain fish stocks and conserve the resource. In several species landings are continually decreasing, while, in addition, the measure generates a series of common practices that are incompatible with the conservation objective. Political pressures usually lead to considerable alterations of the scientist's recommendations, resulting in regular overestimation of the resource capacity. For the time being fisheries management in the European Union (EU) has little to gain from the use of MATACs and/or MSTACs.