Catch composition and conservation management of a human-dolphin cooperative cast-net fishery in the Ayeyarwady River, Myanmar

A study of the catch composition of a cooperative fishery practiced between cast-net fishermen and Irrawaddy dolphins (Orcaella brevirostris) in the Ayeyarwady River, Myanmar, was conducted at fishing grounds near Myay Zun, Indown, The‘ Kyun and Hsithe during November and December 2006 and 2007. A total of 4139 fish from 42 species and five crustaceans from a single species were recorded in 1099 net casts made during 33 fishing sessions. Sufficient data were only available to conduct in-depth analyses of catches obtained from Myay Zun (776 net casts, 41.2% while cooperating with dolphins). These analyses indicated that catch per cast, defined by the number of fish, their weight and economic value, was higher (Mann-Whitney P < 0.001) during both 2006 (about double for all parameters) and 2007 (about triple for all parameters) while the dolphins were cooperating with fishermen. Differences in catch between cooperative and non-cooperative net casts were primarily explained by the much higher frequency of empty catches (Chi-square P < 0.001, df = 3 during both 2006 and 2007) recorded during non-cooperative casts (68.3% and 71.3% in 2006 and 2007, respectively) versus cooperative casts (13.7% and 31.6% in 2006 and 2007, respectively). Overall, fish catch could be described as meager, which may partially be explained by the abnormal timing of flow recession during both years. However, the cast-net fishermen also consistently reported dramatically depleted catches in recent years due to illegal electric fishing. Elimination of electric fishing in a recently established protected area will be crucial for conserving the dolphins and the cooperative cast-net fishery.     

Effects of fishing protection on the genetic structure of fish populations

Marine reserves have been identified as an important tool in the management of fishery resources and their number is increasing rapidly, most of them being on islands. However, knowledge on the real effect of protection from fishing on the genetic structure of populations, the spatial scales involved, or the suitability of islands as reserves in terms of connectivity, is scarce. This paper analyses the effects of fishery protection on the genetic structure of populations of Diplodus sargus, a target species, in protected and non-protected areas of the western Mediterranean. Populations studied showed high genetic variability at spatial scales from 10¹ to 10³ km. Protected areas have significantly higher allelic richness. The lower levels of heterozygosis and higher heterozygote deficit showed by islands compared with coastal areas makes clear the importance of considering the connectivity processes when designing a MPA.     

Competition for shifting resources in the southern Benguela upwelling: Seabirds versus purse-seine fisheries

In the southern Benguela upwelling ecosystem off the west coast of South Africa, seabird populations are decreasing dramatically because of reduced availability of pelagic fish. We tested the hypothesis that the west coast fishing industry is competing for the remaining stocks of anchovy and sardine with the largest colony of Vulnerable Cape Gannets (Morus capensis) along the Atlantic coast. Using GPS-tracking of the birds, echo-sounding of pelagic fish, and vessel log books, we located overlap areas between bird foraging ranges, pelagic fish distribution, and fishing activities. We then compared fish catches by gannets and vessels within their joint foraging zones. In October 2007, purse-seine fishing grounds and gannet foraging areas overlapped by only 13%. However, for a 1-month period, the amount of fish removed from this area by purse-seine boats amounted to 41% of the food requirements of the 72,000 gannets breeding on Malgas Island (25% of the world population). The fishery’s catch in this area is significant in terms of its potential impact on gannets, but comprises only 3.6% of total fishery catch. Based on this finding, the rapidly decreasing size of the gannet colony and the stated objectives of South Africa’s Marine Living Resources Act of 1998, the case for considering and experimenting with at-sea ‘no-take’ areas for the purse-seine fishery is strong. Efforts to establish whether ‘no-take’ fishing zones increase food availability for top predators is an important next step in conservation of the southern Benguela Ecosystem.     

Just passing through: Global change and the conservation of biodiversity in protected areas

Climate and land-use changes are expected to cause many species to shift into or beyond the boundaries of protected areas, leading to large turnover in species composition. Here, we tested whether long-established protected areas in Canada were more robust to such climate change impacts than areas with no formal protection by measuring changes in modeled butterfly species distributions (n = 139) within them. We used a recently established distribution modeling technique, Maxent, to model butterfly species’ distributions in two epochs (1900-1930 and 1960-1990). We compared rates of butterfly species richness and composition change within protected areas against distributions of randomly selected, ecologically similar, but non-protected, areas. Change in species richness and composition within protected areas were, for the most part, the same as changes observed among random areas outside protected area boundaries. These results suggest that existing protected area networks in Canada have provided little buffer against the impacts of climate change on butterfly species richness, possibly because land-use change surrounding long-standing protected areas has not been substantial enough to elevate the habitat protection afforded by these protected areas relative to other areas. Although protected areas are unarguably beneficial in conserving biological diversity, their capacity to maintain habitat appears insufficient to prevent broader-scale climate changes from sweeping species beyond their boundaries.     

From both sides: Dire demographic consequences of carnivorous mice and longlining for the Critically Endangered Tristan albatrosses on Gough Island

The IUCN recently uplisted the Tristan albatross (Diomedea dabbenena) to Critically Endangered. Here we present new data indicating negative population trends on Gough Island arising from low adult survival (∼91%, ascribed to accidental mortality on fishing gear) and low breeding success (averaging 32%, due to mouse predation). Fledgling production from 1979 to 2007 and numbers of incubating adults from 1956 to 2007 have both decreased by ∼1% p.a. Consecutive annual counts of incubating adults and a population model permit the first reliable estimates of the Tristan albatross population, presently 5400 breeding adults and 11,300 birds in all age- and stage-classes. Population models explore scenarios of likely demographic trends using combinations of hypothetical best-case estimates vs. observed estimates for two key parameters: adult survival and breeding success. These scenarios highlight the relative benefits to the species of eradicating mice or mitigating bycatch. The model scenario using observed estimates predicts annual growth rate at −2.85%. Adult survival rates have probably decreased in recent years, concomitant with increased longline fishing effort, which might explain the discrepancy between counts and modelled trends. Negative trends cannot be reversed by improving breeding success alone, and adult survival must exceed an improbable 97% to balance the current chick production. A worst-case scenario including a fixed number of adult deaths annually predicted a catastrophic 4.2% p.a. decrease and extinction in ∼30 years. Population growth was most sensitive to adult survival, but even using an adult survival estimate without fishery mortality, current breeding success is insufficient to maintain the population. These findings do not support the ‘compensatory mitigation of bycatch’ model (offsetting bycatch impacts by eradicating invasive species), and the impacts of both fishery mortality and mouse predation must be addressed to improve the conservation status of the Critically Endangered Tristan albatross.     

From common to rare: The case of the Mediterranean common dolphin

Although overfishing has been recognized as responsible for the decline of major fish stocks, it has been less easy to demonstrate its indirect and detrimental effects on marine mammals, particularly dolphins. Competition with fisheries for the same food resources has been hypothesized to have led to the decline of several species of dolphins, including the endangered Mediterranean short-beaked common dolphin. Based on an ecosystem model for the Inner Ionian Sea Archipelago, a former hotspot for common dolphins in the Mediterranean Sea, we investigated the effect of increasing fishing effort on common dolphins, its prey and on marine biodiversity and we evaluated the outcomes of different fisheries closures (1 – closure of the purse seine fishery, 2 – closure of purse seine, trawl and beach seine fisheries, 3 – entire area closed to fisheries) ran between the years 2011 and 2030. Our results showed that local fisheries have negatively impacted the marine biodiversity of the ecosystem causing sharp declines of common dolphins and major fish stocks and weakening the robustness of the marine food web. The implementation of fisheries closures would gradually recover fish stocks, while common dolphins would increase more pronouncedly only if the study area was to be closed to all fisheries. As shown in this study, common dolphins have reflected ecosystem changes and degradation over time. Ensuring the survival of dolphin populations is thereby essential to enhance marine ecosystems and ensure sustainable fishing.     

Long-term trends in lobster populations in a partially protected vs. no-take Marine Park

Increasing the level of protection afforded to the marine environment requires assessment of the efficacy of existing marine protected areas (MPAs) in protecting exploited species. Long-term data from before and after the establishment of MPAs provide a rare but valuable opportunity to assess these effects. In this study we present long-term data (1977-2005) from before and after park establishment, on the abundance of spiny lobster Jasus edwardsii from fixed sites in a no-take marine park and a recreationally fished marine park, to assess the efficacy of no-take vs. partial protection. Lobster densities were comparable between both marine parks prior to park establishment, but the response of lobster populations differed markedly following protection. On average, legal-sized lobster were eleven times more abundant and biomass 25 times higher in the no-take marine park following park establishment, while in the partially protected marine park there has been no significant change in lobster numbers. Furthermore, no difference was found in densities of legal-sized lobster between the partially protected marine park and nearby fully-fished sites (<1 per 500 m²). Long-term data from fully fished and partially protected sites suggest long-term declines in lobster populations and reflect regional patterns in catch per unit effort estimates for the fishery. The long-term patterns presented provide an unequivocal example of the recovery of lobster populations in no-take MPAs, but clearly demonstrate that allowing recreational fishing in MPAs has little benefit to populations of exploited species such as J. edwardsii.     

Live coral trade impacts on the mushroom coral Heliofungia actiniformis in Indonesia: Potential future management approaches

The poorly regulated aquarium trade in live corals poses yet another threat to fragile coral reef ecosystems. The Indonesian authorities routinely allocate some of the highest trade quotas in South Sulawesi to Heliofungia actiniformis despite a lack of data on the impacts of current collection practices on this species. Semi-structured interviews with fishermen and in situ surveys revealed a size-selective fishery towards small polyps. This resulted in a shift of size-frequency distributions, and reduced overall abundances at harvested sites. Total mortality rates calculated using a catch curve approach at harvested sites were significantly higher compared to those known from unharvested sites for polyps sized 0-11 cm. Recorded exploitation rates were 0.1 and 0.7 for polyps sized 0-4 cm and 4-11 cm respectively. The application of a utility per recruit approach, calculated with a Thompson and Bell model, revealed maximum potential economic yield to occur at a size of 5 cm, corresponding to an age of 5 years. This is 5 years before the attainment of reproductive maturity, and 15 years before the attainment of maximum biomass yield per recruit. A predictive model indicated the need for a 5 cm size limit to curb economic overfishing, and protect attached anthocauli stalks capable of maintaining the trade through continued asexual reproduction. In addition, a reduction of exploitation rates for polyps in the 4-11 cm size bracket to 0.5 is urgently needed. Calculations reveal that this would in fact be possible without lowering current profits. Achieving long term sustainability will in addition to a reduction of harvest quotas necessitate an effective protection of spawning stocks through stricter enforcement of existing marine protected areas.     

Community-based conservation results in the recovery of reef fish spawning aggregations in the Coral Triangle

In the Coral Triangle community-based marine protected areas (MPAs) are being established at a prolific rate. Their establishment can benefit both fisheries and biodiversity, and they provide both a socially and economically acceptable means of managing coral reefs in developing nations. However, because such MPAs are typically small (usually <0.5 km²), they will rarely provide protection to large mobile fishes. An exception to this limitation may exist when community-based MPAs are established to protect small sites where vital processes occur, such as fish spawning aggregations (FSAs). To test the effectiveness of small (0.1–0.2 km²) MPAs for protecting FSAs, we monitored three FSA sites where brown-marbled grouper (Epinephelus fuscoguttatus), camouflage grouper (Epinephelus polyphekadion) and squaretail coralgrouper (Plectropomus areolatus) aggregate to spawn. Sites were monitored during peak reproductive periods (several days prior to each new moon) between January 2005 and November 2009. All three sites are located in New Ireland Province, Papua New Guinea, and had been exploited for decades, but in 2004 two sites were protected by the establishment of community-based MPAs. The third site continued to be exploited. Over the monitoring period densities of E. fuscoguttatus and E. polyphekadion increased at both MPAs, but not at the site that remained open to fishing. At one MPA the densities of E. polyphekadion increased tenfold. Our findings demonstrate that community-based MPAs that are appropriately designed and adequately enforced can lead to the recovery of populations of vulnerable species that aggregate to spawn.     

Post-breeding season distribution of black-footed and Laysan albatrosses satellite-tagged in Alaska: Inter-specific differences in spatial overlap with North Pacific fisheries

We integrated satellite-tracking data from black-footed albatrosses (Phoebastria nigripes; n = 7) and Laysan albatrosses captured in Alaska (Phoebastria immutabilis; n = 18) with data on fishing effort and distribution from commercial fisheries in the North Pacific in order to assess potential risk from bycatch. Albatrosses were satellite-tagged at-sea in the Central Aleutian Islands, Alaska, and tracked during the post-breeding season, July-October 2005 and 2006. In Alaskan waters, fishing effort occurred almost exclusively within continental shelf and slope waters. Potential fishery interaction for black-footed albatrosses, which most often frequented shelf-slope waters, was greatest with sablefish (Anoplopoma fimbria) longline and pot fisheries and with the Pacific halibut (Hippoglossus stenolepsis) longline fishery. In contrast, Laysan albatrosses spent as much time over oceanic waters beyond the continental shelf and slope, thereby overlapping less with fisheries in Alaska than black-footed albatrosses. Regionally, Laysan albatrosses had the greatest potential fishery interaction with the Atka mackerel (Pleurogrammus monopterygius) trawl fishery in the Western Aleutian Islands and the sablefish pot fishery in the Central Aleutian Islands. Black-footed albatrosses ranged further beyond Alaskan waters than Laysan albatrosses, overlapping west coast Canada fisheries and pelagic longline fisheries in the subarctic transition domain; Laysan albatrosses remained north of these pelagic fisheries. Due to inter-specific differences in oceanic distribution and habitat use, the overlap of fisheries with the post-breeding distribution of black-footed albatrosses is greater than that for Laysan albatrosses, highlighting inter-specific differences in potential vulnerability to bycatch and risk of population-level impacts from fisheries.     

Effects of fishing and protection on Brazilian reef fishes

The vast Brazilian coast harbors unique and diverse reef fish communities. Unfortunately, relatively little is known about the impact of fishing on these fish species, and few management or conservation efforts are being made to protect them. Here, we examine the effect of different levels of protection on the composition, abundance, and size structure of reef fish species along a 2500 km portion of the Brazilian coastline, noting in particular the relative abundance of endemics and the effect of protection on these species. Pairwise comparisons of sites with different protection status (more versus less protected) were used to determine the potential responses of reef fishes to the establishment of marine protected areas. Highly targeted species (top predators and large herbivores) were significantly more abundant and larger in size within sites with a higher degree of protection, indicating that they benefit from protection, while lightly fished and unfished species were not. These results are consistent with past work documenting the responses of species to protection. Here, we use our results in particular to suggest strategies and provide expectations for managing and protecting Brazilian reef fisheries. Because this biogeographic province lies entirely within the jurisdiction of a single nation, there may be unique and significant opportunities to effectively manage and conserve these fish species.     

Improving social acceptability of marine protected area networks: A method for estimating opportunity costs to multiple gear types in both fished and currently unfished areas

We present a novel method for calculating the opportunity costs to fishers from their displacement by the establishment of marine protected areas (MPAs). We used a fishing community in Kubulau District, Fiji to demonstrate this method. We modelled opportunity costs as a function of food fish abundance and probability of catch, based on gear type and market value of species. Count models (including Poisson, negative binomial and two zero-inflated models) were used to predict spatial abundance of preferred target fish species and were validated against field surveys. A profit model was used to investigate the effect of restricted access to transport on costs to fishers. Spatial distributions of fish within the three most frequently sighted food fish families (Acanthuridae, Lutjanidae, Scaridae) varied, with greatest densities of Lutjanidae and Acanthuridae on barrier forereefs and greatest densities of Scaridae on submerged reefs. Modelled opportunity cost indicated that highest costs to fishers arise from restricting access to the barrier forereefs. We included our opportunity cost model in Marxan, a decision support tool used for MPA design, to examine potential MPA configurations for Kubulau District, Fiji Islands. We identified optimum areas for protection in Kubulau with: (a) the current MPA network locked in place; and (b) a clean-slate approach. Our method of modelling opportunity cost gives an unbiased estimate for multiple gear types in a marine environment and can be applied to other regions using existing species data.     

Assessing the effects of marine protected area (MPA) on a reef fish assemblage in a northwestern Mediterranean marine reserve: Identifying community-based indicators

Marine protected areas (MPAs) are increasingly envisaged as a tool to manage coastal ecosystems and fisheries. Assessment of their performance with respect to management objectives is therefore important. A number of MPAs provided conservation benefits for fished species. Observed benefits do not apply to all species at all times, and responses to protection are also highly variable among fish taxa. Among the many empirical studies on marine reserves, only a few designs considered ‘before and after data’ and spatial variation. In this paper, we are interested in assessing the effect of a no-take reserve on the reef fish assemblage in a northwestern Mediterranean example. Data were obtained from a three-year survey using underwater visual censuses (UVC), before and after MPA establishment. Permutational multivariate analysis of variance (PERMANOVA) and multivariate regression trees (MRT) were used to evaluate the effects of reserve protection on the reef fish assemblage, while accounting for habitat. Modelled biological responses were abundances and diversity indices calculated at different levels of the assemblage. Significant effects were found for many of these metrics. In addition to PERMANOVA, univariate models provided more insight into the magnitude and direction of effects. The most sensitive metrics were related to large species and species targeted by fishing. These results may be used to choose the metrics that are more suitable as community-based indicators of MPA impact in the perspective of monitoring programs.     

Protection from harvesting restores the natural social structure of eastern wolf packs

Legal and illegal killing of animals near park borders can significantly increase the threat of extirpation for populations living within ecological reserves, especially for wide-ranging large carnivores that regularly travel into unprotected areas. While the consequences of human-caused mortality near protected areas generally focus on numerical responses, little attention has been given to impacts on social dynamics. For wolves, pack structure typically constitutes an unrelated breeding pair, their offspring, and close relatives, but intense harvest may increase adoption of unrelated individuals into packs. Concerns that high human-caused mortality outside Algonquin Park, Canada threatened the persistence of eastern wolves, led to implementation of a harvest ban in surrounding townships. We combined ecological and genetic data to show that reducing anthropogenic causes of mortality can restore the natural social structure of kin-based groups despite the absence of a marked change in density. Since implementation of the harvest ban, human-caused mortality has decreased (P = 0.000006) but been largely offset by natural mortality, such that wolf density has remained relatively constant at approximately three wolves/100 km². However, the number of wolf packs with unrelated adopted animals has decreased from 80% to 6% (P = 0.00003). Despite the high kinship within packs, incestuous matings were rare. Our results indicate that even in a relatively large protected area, human harvesting outside park boundaries can affect evolutionarily important social patterns within protected areas. This research demonstrates the need for conservation policy to consider effects of harvesting beyond influences on population size.     

Effects of habitat characteristics and sedimentation on performance of marine reserves in St. Lucia

This study examines factors affecting the rate and extent of biomass build-up among commercially important groupers, snappers, grunts, parrotfish and surgeonfish in a network of four marine reserves in southwest St. Lucia, Caribbean. Reserves constituted 35% of the total reef area originally available for fishing. Protection was instigated in 1995 after a baseline survey with annual or biennial censuses performed until 2002. Each survey consisted of 114 fifteen minute fish counts in reserves and 83 in fishing grounds, at depths of 5 m and 15 m in a 10 m diameter counting area. Estimates of number and size (cm) of target species were used to calculate fish family biomass. Data were analysed using three-way ANOVA in a before-after-control-impact pairs (BACIP) design. All families increased significantly in biomass over time at nearly all sites. Increases were greater in reserves than fishing grounds, except for grunts, and responses were strongest in parrotfish and surgeonfish. The combined biomass of families more than quadrupled in reserves and tripled in fishing grounds between 1995 and 2002. During this period coral cover declined by 46% in reserves and 35% in fishing grounds. Multiple regression showed that neither habitat characteristics nor habitat deterioration significantly affected rates of biomass build-up. The key factor was protection from fishing, which explained 44% of the variance in biomass growth. A further 28% of the variance was explained by sedimentation, a process known to stress reef invertebrates, significantly reducing the rate of biomass build-up. St. Lucia’s reserves succeeded in producing significant gains to fish stocks despite coral cover and structural complexity falling steeply over the period of the study.     

A new abundance estimate for Maui’s dolphin: What does it mean for managing this critically endangered species?

Hector’s dolphin Cephalorhynchus hectori is found only in New Zealand waters. We carried out a population survey of the North Island subspecies Cephalorhychus hectori maui, also known as Maui’s dolphin. The total population size estimate is 111 individuals (95% confidence interval = 48-252). The small population size confirms its critically endangered IUCN status. A sustainable level of human-caused mortality for this population would be 0.16 (one dolphin every 6.4 years). This essentially means that fisheries bycatch, and where possible other human impacts, need to be eliminated to allow population recovery. A protected area has been created to reduce the threat from entanglement in fishing gear. Gillnet fishing is prohibited along a 210 nautical mile stretch of coastline. The main concerns are that gillnet fishing is still allowed inside harbours and trawling continues inside the protected area.     

The spatial extent of termite influences on herbivore browsing in an African savanna

Termite mounds form islands of fertility in savanna landscapes and create foraging hotspots for herbivores, but the magnitude and spatial extent of these influences is unknown. We mapped terrain, termite mound and woody vegetation three-dimensional (3-D) structure at 56 cm resolution across a large-scale (254 ha), long-term (34 years) herbivore exclusion experiment in the Kruger National Park, with the Carnegie Airborne Observatory (CAO). We compared vegetation 3-D structure in areas protected from herbivores with those accessible to herbivores, both on termite mounds and in the landscape matrix between termite mounds. Termite mound density was 1.1 ha⁻¹ across the study area and mound size did not differ between protected and accessible areas. Woody vegetation canopy cover was ∼100% greater on protected than accessible mounds, but was only ∼20% greater in the protected inter-mound matrix when compared to the accessible matrix. Woody canopy height class distributions differed significantly between protected and accessible areas, with the tallest vegetation (>10 m) occurring on protected termite mounds. The impacts of herbivore browsing were evident at distances of up to 20 m from termite mound centres. Spatial analysis of mound distribution revealed that the sphere of termite mound influence constitutes ∼20% of the total landscape. Termite influences on herbivore browsing operate at scales much larger than the spatial extent of their mound building activities.     

Assessing the performance of the existing and proposed network of marine protected areas to conserve marine biodiversity in Chile

The growing concern about the profound influence of human activities on marine ecosystems has been the driving force behind the creation of marine reserves in the last few decades. With almost 4200 km of coastline, Chile has not been the exception to this trend. A set of conservation priority sites has recently been proposed by the Chilean government to expand the current marine reserve network. In this study, we used the most comprehensive information currently available on the distribution of 2513 marine species in Chile to assess the efficiency of the existing system of marine protected areas (MPA) and the conservation priority sites identified by the government. Additionally, we evaluated the vulnerability of the reserve network selected with respect to threatening human activities. Our results show that both the existing protected areas and the proposed priority sites are relatively effective at protecting Chilean marine biodiversity. However, the majority of the species that are not represented within the existing or projected MPA network have very restricted distributions and are, therefore, of high conservation concern. To cover all species requires a network of 35 MPAs (46% of the total number of planning units). Many of the sites identified as irreplaceable present conflict with one or more human activities, particularly in the central region of the country. This study emphasizes the need for a systematic conservation planning approach to maximize the representation of species and prioritize those areas where conflicts between marine biodiversity conservation and human activities may occur.     

Measurement, management and mitigation of operational interactions between the South Australian Sardine Fishery and short-beaked common dolphins (Delphinus delphis)

This study arose from recommendations given in response to a legislated ecological assessment of the South Australian Sardine Fishery in 2004, urging it to: (i) attempt to mitigate operational interactions with marine mammals if excessive levels were detected; and (ii) improve the accuracy of their reporting of these events.An initial observer program revealed high rates of encirclement and mortality (1.78 and 0.39 dolphins per net-set, respectively) of short-beaked common dolphins (Delphinus delphis). This equated to an estimate of 1728 encirclements and 377 mortalities across the entire fleet over the same period. The average time taken for fishers to respond to encirclements was 135.93 ± 3.72 min and 21.3% of encircled animals subsequently died. During that time, fishers only reported 3.6% of encirclements and 1.9% of mortalities recorded by observers.A code of practice (CoP) was subsequently introduced aimed at mitigating operational interactions. A second observer program revealed a significant reductions in the observed rates of dolphin encirclement (0.22; down 87.3%) and mortality (0.01; down 97.1%) with an estimate of 169 and eight, respectively. The average time taken for fishers to respond to dolphin encirclements also reduced to 16.33 ± 4.67 min (down 76.9%) and the proportion of encircled animals that subsequently died reduced to 5.0%. Agreement between industry reports and observer records improved, with the fishery reporting 57.9% and 58.9% of the rate of encirclements and mortalities, respectively, recorded by observers.A number of avoidance and release strategies in the CoP may have been responsible for these improvements. In particular, fishers were required to delay or relocate their activities if dolphins were observed prior to fishing and to release encircled dolphins immediately or abort the fishing event if release procedures were unsuccessful. Future improvements to the CoP include: (i) improved response times when an encircled dolphin is detected; (ii) better use of behavioural cues for deciding when to abort a net-set; (iii) ceasing fishing during rough weather; and (iv) continuing to increase reporting accuracy by fishers. It is also recommended that the abundance, movements and boundaries of the common dolphin population in the region be determined, so that the impact of fishing activities on their status can be established.     

Interactions between poaching and management policy affect marine reserves as conservation tools

To explore the effects of poaching within marine reserve boundaries under three different management policies this analysis uses a simple age-structured reserve model based on yield maximization or reproductive thresholds of Black rockfish (Sebastes melanops). Departures from the traditional assumptions of full compliance to reserve boundaries alter the conclusions of prior modeling work that demonstrate yield equivalence to no-reserve effort control management and augmented reproductive benefits when small reserves are implemented. By degrading the recruitment subsidization effect to nonreserve areas from protected reserve populations, poaching resulted in negative externalities for compliant fishermen in open areas in terms of yield and degraded the reproductive output and age-structure of the system. All three policies required effort reduction in open areas as a response to poaching in reserves. The strength of the impacts from poaching varied with policy choice and harvest intensity in the reserve, where at the highest level of poaching modeled here (15% annual exploitation rate of the vulnerable reserve population) biological and fishery benefits of implementing reserves were totally negated. Under the assumptions of this model, a policy managing for a reproductive threshold that excludes the reserve population is the precautionary choice if poaching is likely. The results of this exercise emphasize the importance of garnering compliance to reserve boundaries from resource-users for spatial closures to be successful ocean management tools.