Potential Catch Research Articles

Applicability of remote sensing oceanographic data in the detection of potential fishing grounds of Rastrelliger kanagurta in the archipelagic waters of Spermonde, Indonesia

Rastrelliger kanagurta is among the pelagic fish of commercial value caught in the archipelagic waters of Spermonde, Indonesia. The dynamic oceanographic pattern in this area influences the distribution of this pelagic fish. Understanding the relationship between the distribution of fish and environmental factors is important in exploring fisheries resources. This study used Rastrelliger kanagurta fishing-catch data during the high-catch season in the second quarter, which was from April to June (2008 and 2009), and satellite data of chlorophyll-a (chl-a), and sea surface temperature (SST) from MODIS-Aqua. The study aimed to identify the relationship between fish distribution with chl-a and SST constructed using the Generalized Additive Model (GAM), detect the potential fishing grounds, and determine the impact of climate change on fish distribution based on temperature projection of IPCC-AR5-RCPs. The distribution of Rastrelliger kanagurta was significantly associated (p<0.0001) with the preferred range of chl-a at 0.30–0.40mg/m3 and SST at 30.00–31.00°C. The potential fishing ground maps showed that areas with high potential catch were located near the coast to offshore (3–20M), with acceptable level of map accuracy at 83.34%; with kappa value at 0.70. Increased temperature of 1.80°C resulted in movement of potential fishing grounds to the southern part of Makassar Straits leading to the archipelagic waters of Spermonde. In contrast, increased temperature of 2.60°C and 3.30°C resulted in lesser potential fishing grounds area which shifted further to the south. The results of this study indicated applicability of remote sensing in contributing to optimal fishing effort and decision making for long-term management of Rastrelliger kanagurta resources.

The potential for blue growth in marine fish yield, profit and abundance of fish in the ocean

The oceans provide food, employment and income for billions of people. Using data from scientific stock assessments and a statistical model for other fish stocks the past and present status, and the potential catch, abundance and profit for 4713 fish stocks constituting 78% of global fisheries are estimated. Three major scenarios of future trends are considered; business as usual (BAU) in which largely unmanaged fisheries move towards bioeconomic equilibrium but where well-managed fisheries maintain their management, maximum sustainable yield (MSY) in which fisheries are managed to maximize yield, and fisheries reform (REF) where the competitive race to fish is eliminated and fisheries are managed to maximize profit. The future prospects differ greatly based on region of the world and product type. This analysis forecasts that yield in major tuna and forage fish species will remain roughly the same as current levels under all three scenarios, while there does appear to be potential for increased yield of whitefish. There is considerable room for increased profit in most of these fisheries from better management. Increased yield will come from rebuilding overexploited stocks, reducing fishing mortality on stocks that are still abundant but fished at high rates, and surprisingly from fishing some stocks harder. Indeed in Europe and North America the primary potential for increased yield comes from fully exploiting stocks that are now lightly exploited. Asia provides the greatest opportunity for increased fish abundance and increased profit by fisheries reform that would lead to reduced fishing pressure.

Estimating efficiency of survey and commercial trawl gears from comparisons of catch-ratios

AbstractAssumptions about gear efficiency and catchability influence estimates of abundance, mortality, reference points and catch potential. Despite the need to better quantify fishing effects on some target species and on many non-target species taken as bycatch, there are few gear efficiency estimates for some of the most widely deployed towed fishing gears in the northeast Atlantic. Here, we develop a method that applies generalised additive models to catch-at-length data from trawl surveys and a commercial catch and discard monitoring program in the North Sea to estimate catch-ratios. We then rescale these catch-ratios and fit relationships to estimate gear efficiency. When catches of individuals by species were too low to enable species-specific estimates, gear efficiency was estimated for species-groups. Gear efficiency (and associated uncertainty) at length was ultimately estimated for 75 species, seven species-groups and for up to six types of trawl gear per species or species-group. Results are illustrated for dab (Limanda limanda), grey gurnard (Eutrigula gurnardus) and thornback ray (Raja clavata), two common non-target species and a depleted elasmobranch. All estimates of gear efficiency and uncertainty, by length, species, species-group and gear, are made available in a supplementary data file.

Large benefits to marine fisheries of meeting the 1.5°C global warming target.

Translating the Paris Agreement to limit global warming to 1.5°C above preindustrial level into impact-related targets facilitates communication of the benefits of mitigating climate change to policy-makers and stakeholders. Developing ecologically relevant impact-related targets for marine ecosystem services, such as fisheries, is an important step. Here, we use maximum catch potential and species turnover as climate-risk indicators for fisheries. We project that potential catches will decrease by more than 3 million metric tons per degree Celsius of warming. Species turnover is more than halved when warming is lowered from 3.5° to 1.5°C above the preindustrial level. Regionally, changes in maximum catch potential and species turnover vary across ecosystems, with the biggest risk reduction in the Indo-Pacific and Arctic regions when the Paris Agreement target is achieved.

Projected change in global fisheries revenues under climate change.

Previous studies highlight the winners and losers in fisheries under climate change based on shifts in biomass, species composition and potential catches. Understanding how climate change is likely to alter the fisheries revenues of maritime countries is a crucial next step towards the development of effective socio-economic policy and food sustainability strategies to mitigate and adapt to climate change. Particularly, fish prices and cross-oceans connections through distant water fishing operations may largely modify the projected climate change impacts on fisheries revenues. However, these factors have not formally been considered in global studies. Here, using climate-living marine resources simulation models, we show that global fisheries revenues could drop by 35% more than the projected decrease in catches by the 2050 s under high CO2 emission scenarios. Regionally, the projected increases in fish catch in high latitudes may not translate into increases in revenues because of the increasing dominance of low value fish, and the decrease in catches by these countries’ vessels operating in more severely impacted distant waters. Also, we find that developing countries with high fisheries dependency are negatively impacted. Our results suggest the need to conduct full-fledged economic analyses of the potential economic effects of climate change on global marine fisheries.

Overview of West African fisheries under climate change: Impacts, vulnerabilities and adaptive responses of the artisanal and industrial sectors

Climate change affects ocean conditions, fish stocks and hence fisheries. In West Africa, climate change impacts on fisheries were projected to be mainly negative through multi-facet ways. However, analysis of adaptation responses of fishers to climate change impacts is scarce. This paper reviews the impacts on climate change on fisheries in West Africa and discusses the potential adaptation strategies adopted by both the artisanal and industrial fishing sectors. Overall, climate change and over-exploitation have altered species composition of fisheries catches in West Africa. The effect of ocean warming on fisheries is indicated by the increase in dominance of warmer water species in the landings, shown from an increase in Mean Temperature of Catch, in the region. Climate change induced changes in potential catch and species composition, which inherently have similar symptoms as over-exploitation, are expected to have repercussions on the economic and social performance of fisheries. Both artisanal and industrial sectors may adapt to these changes mainly through expansion of fishing ground that increases operation costs. Our results highlight that historical changes in target species are more common in industrial than artisanal fisheries. This result challenges the prevailing assumption that artisanal fisheries, given their limited movement capacity, would adapt to climate change by shifting target species and/or gear type.

Structural uncertainty in projecting global fisheries catches under climate change

The global ocean is projected to be warmer, less oxygenated and more acidic in the 21st century relative to the present day, resulting in changes in the biogeography and productivity of marine organisms and ecosystems. Previous studies using a Dynamic Bioclimate Envelope Model (DBEM) projected increases in potential catch in high latitude regions and decreases in tropical regions over the next few decades. A major structural uncertainty of the projected redistribution of species and fisheries catches can be attributed to the habitat suitability algorithms used. Here, we compare the DBEM projections of potential catches of 500 species of exploited marine fishes and invertebrates from 1971 to 2060 using three versions of DBEM that differ by the algorithm used to predict relative habitat suitability: DBEM-Basic, DBEM-Maxent and DBEM-Aquamaps. All the DBEM models have similar skill in predicting the occurrence of exploited species and distribution of observed fisheries production. Globally, the models project a decrease in catch potential of 3% to 13% by 2050 under a high emissions scenario (Representative Concentration Pathway 8.5). For the majority of the modelled species, projections by DBEM-Maxent are less sensitive to changes in ocean properties than those by DBEM-Aquamaps. The mean magnitude of projected changes relative to differences between projections differ between regions, being highest (>1 times the standard deviation) in the tropical regions and Arctic Ocean and lowest in three of the main Eastern Boundary Upwelling regions, the eastern Indian Ocean and the Southern Ocean. These results suggest that the qualitative patterns of changes in catch potential reported in previous studies are not affected by the structural uncertainty of DBEM, particularly in areas where catch potential was projected to be most sensitive to climate change. However, when making projections of fish stocks and their potential catches using DBEM in the future, multiple versions of DBEM should be used to quantify the uncertainty associated with structural uncertainty of the models. Overall, this study contributes to improving projection of future changes in living marine resources by exploring one aspect of the cascade of uncertainty associated with such projections.

Projected Scenarios for Coastal First Nations' Fisheries Catch Potential under Climate Change: Management Challenges and Opportunities.

Studies have demonstrated ways in which climate-related shifts in the distributions and relative abundances of marine species are expected to alter the dynamics and catch potential of global fisheries. While these studies assess impacts on large-scale commercial fisheries, few efforts have been made to quantitatively project impacts on small-scale subsistence and commercial fisheries that are economically, socially and culturally important to many coastal communities. This study uses a dynamic bioclimate envelope model to project scenarios of climate-related changes in the relative abundance, distribution and richness of 98 exploited marine fishes and invertebrates of commercial and cultural importance to First Nations in coastal British Columbia, Canada. Declines in abundance are projected for most of the sampled species under both the lower (Representative Concentration Pathway [RCP] 2.6) and higher (RCP 8.5) emission scenarios (-15.0% to -20.8%, respectively), with poleward range shifts occurring at a median rate of 10.3 to 18.0 km decade-1 by 2050 relative to 2000. While a cumulative decline in catch potential is projected coastwide (-4.5 to -10.7%), estimates suggest a strong positive correlation between the change in relative catch potential and latitude, with First Nations’ territories along the northern and central coasts of British Columbia likely to experience less severe declines than those to the south. Furthermore, a strong negative correlation is projected between latitude and the number of species exhibiting declining abundance. These trends are shown to be robust to alternative species distribution models. This study concludes by discussing corresponding management challenges that are likely to be encountered under climate change, and by highlighting the value of joint-management frameworks and traditional fisheries management approaches that could aid in offsetting impacts and developing site-specific mitigation and adaptation strategies derived from local fishers’ knowledge.

Building confidence in projections of the responses of living marine resources to climate change

Abstract The Fifth Assessment Report of the Intergovernmental Panel on Climate Change highlights that climate change and ocean acidification are challenging the sustainable management of living marine resources (LMRs). Formal and systematic treatment of uncertainty in existing LMR projections, however, is lacking. We synthesize knowledge of how to address different sources of uncertainty by drawing from climate model intercomparison efforts. We suggest an ensemble of available models and projections, informed by observations, as a starting point to quantify uncertainties. Such an ensemble must be paired with analysis of the dominant uncertainties over different spatial scales, time horizons, and metrics. We use two examples: (i) global and regional projections of Sea Surface Temperature and (ii) projection of changes in potential catch of sablefish (Anoplopoma fimbria) in the 21st century, to illustrate this ensemble model approach to explore different types of uncertainties. Further effort should prioritize understanding dominant, undersampled dimensions of uncertainty, as well as the strategic collection of observations to quantify, and ultimately reduce, uncertainties. Our proposed framework will improve our understanding of future changes in LMR and the resulting risk of impacts to ecosystems and the societies under changing ocean conditions.

Using a spatially structured life cycle model to assess the influence of multiple stressors on an exploited coastal-nursery-dependent population

Exploited coastal-nursery-dependent fish species are subject to various stressors occurring at specific stages of the life cycle: climate-driven variability in hydrography determines the success of the first eggs/larvae stages; coastal nursery habitat suitability controls juvenile growth and survival; and fisheries target mostly adults. A life cycle approach was used to quantify the relative influence of these stressors on the Eastern English Channel (EEC) population of the common sole (Solea solea), a coastal-nursery-dependent flatfish population which sustains important fisheries. The common sole has a complex life cycle: after eggs hatch, larvae spend several weeks drifting in open water. Survivors go on to metamorphose into benthic fish. Juveniles spend the first two years of their life in coastal and estuarine nurseries. Close to maturation, they migrate to deeper areas, where different subpopulations supplied by different nurseries reproduce and are exploited by fisheries. A spatially structured age-and stage-based hierarchical Bayesian model integrating various aspects of ecological knowledge, data sources and expert knowledge was built to quantitatively describe this complex life cycle. The model included the low connectivity among three subpopulations in the EEC, the influence of hydrographic variability, the availability of suitable juvenile habitat and fisheries. Scenarios were designed to quantify the effects of interacting stressors on population renewal. Results emphasized the importance of coastal nursery habitat availability and quality for the population renewal. Realistic restoration scenarios of the highly degraded Seine estuary produced a two-third increase in catch potential for the adjacent subpopulation. Fisheries, however, remained the main source of population depletion. Setting fishing mortality to the maximum sustainable yield led to substantial increases in biomass (+100%) and catch (+33%) at the EEC scale. The approach also showed how climate-driven variability in hydrography is likely to interact with human pressures, e.g., overfishing increased the sensitivity to unfavourable conditions. Our results provided insights into the dynamics of numerous exploited coastal-nursery-dependent species while paving the way toward more robust advice for sustainable management of these resources.

Projecting marine fish production and catch potential in Bangladesh in the 21st century under long-term environmental change and management scenarios

AbstractThe fisheries sector is crucial to the Bangladeshi economy and wellbeing, accounting for 4.4% of national gross domestic product and 22.8% of agriculture sector production, and supplying ca. 60% of the national animal protein intake. Fish is vital to the 16 million Bangladeshis living near the coast, a number that has doubled since the 1980s. Here, we develop and apply tools to project the long-term productive capacity of Bangladesh marine fisheries under climate and fisheries management scenarios, based on downscaling a global climate model, using associated river flow and nutrient loading estimates, projecting high-resolution changes in physical and biochemical ocean properties, and eventually projecting fish production and catch potential under different fishing mortality targets. We place particular interest on Hilsa shad (Tenualosa ilisha), which accounts for ca. 11% of total catches, and Bombay duck (Harpadon nehereus), a low price fish that is the second highest catch in Bangladesh and is highly consumed by low-income communities. It is concluded that the impacts of climate change, under greenhouse emissions scenario A1B, are likely to reduce the potential fish production in the Bangladesh exclusive economic zone by &amp;lt;10%. However, these impacts are larger for the two target species. Under sustainable management practices, we expect Hilsa shad catches to show a minor decline in potential catch by 2030 but a significant (25%) decline by 2060. However, if overexploitation is allowed, catches are projected to fall much further, by almost 95% by 2060, compared with the Business as Usual scenario for the start of the 21st century. For Bombay duck, potential catches by 2060 under sustainable scenarios will produce a decline of &amp;lt;20% compared with current catches. The results demonstrate that management can mitigate or exacerbate the effects of climate change on ecosystem productivity.

Climate change impacts in Latin America and the Caribbean and their implications for development

This paper synthesizes what is known about the physical and biophysical impacts of climate change and their consequences for societies and development under different levels of global warming in Latin America and the Caribbean (LAC). Projections show increasing mean temperatures by up to 4.5 °C compared to pre-industrial by the end of this century across LAC. Associated physical impacts include altered precipitation regimes, a strong increase in heat extremes, higher risks of droughts and increasing aridity. Moreover, the mean intensity of tropical cyclones, as well as the frequency of the most intense storms, is projected to increase while sea levels are expected to rise by ~0.2–1.1 mm depending on warming level and region. Tropical glacier volume is found to decrease substantially, with almost complete deglaciation under high warming levels. The much larger glaciers in the southern Andes are less sensitive to warming and shrink on slower timescales. Runoff is projected to be reduced in Central America, the southern Amazon basin and southernmost South America, while river discharge may increase in the western Amazon basin and in the Andes in the wet season. However, in many regions, there is uncertainty in the direction of these changes as a result of uncertain precipitation projections and differences in hydrological models. Climate change will also reduce agricultural yields, livestock and fisheries, although there may be opportunities such as increasing rice yield in several LAC countries or higher fish catch potential in the southernmost South American waters. Species range shifts threaten terrestrial biodiversity, and there is a substantial risk of Amazon rainforest degradation with continuing warming. Coral reefs are at increasing risk of annual bleaching events from 2040 to 2050 onwards irrespective of the climate scenario. These physical and biophysical climate change impacts challenge human livelihoods through, e.g., decreasing income from fisheries, agriculture or tourism. Furthermore, there is evidence that human health, coastal infrastructures and energy systems are also negatively affected. This paper concludes that LAC will be severely affected by climate change, even under lower levels of warming, due to the potential for impacts to occur simultaneously and compound one another.

Predictive mapping of abalone fishing grounds using remotely-sensed LiDAR and commercial catch data

Defining the geographic extent of suitable fishing grounds at a scale relevant to resource exploitation for commercial benthic species can be problematic. Bathymetric light detection and ranging (LiDAR) systems provide an opportunity to enhance ecosystem-based fisheries management strategies for coastally distributed benthic fisheries. In this study we define the spatial extent of suitable fishing grounds for the blacklip abalone (Haliotis rubra) along 200 linear kilometers of coastal waters for the first time, demonstrating the potential for integration of remotely-sensed data with commercial catch information. Variables representing seafloor structure, generated from airborne bathymetric LiDAR were combined with spatially-explicit fishing event data, to characterize the geographic footprint of the western Victorian abalone fishery, in south-east Australia. A MaxEnt modeling approach determined that bathymetry, rugosity and complexity were the three most important predictors in defining suitable fishing grounds (AUC=0.89). Suitable fishing grounds predicted by the model showed a good relationship with catch statistics within each sub-zone of the fishery, suggesting that model outputs may be a useful surrogate for potential catch.

Improving the Reliability of Fishery Predictions Under Climate Change

The increasing number of publications assessing impacts of climate change on marine ecosystems and fisheries attests to rising scientific and public interest. A selection of recent papers, dealing more with biological than social and economic aspects, is reviewed here, with particular attention to the reliability of projections of climate impacts on future fishery yields. The 2014 Intergovernmental Panel on Climate Change (IPCC) report expresses high confidence in projections that mid- and high-latitude fish catch potential will increase by 2050 and medium confidence that low-latitude catch potential will decline. These levels of confidence seem unwarranted, since many processes are either absent from or poorly represented in the models used, data are sparse and, unlike terrestrial crop projections, there are no controlled experiments. This review discusses methodological issues that affect our understanding of climate impacts, such as how to improve coupled models from physics to fish and how to strengthen confidence in analysis of time series.

Marine capture fisheries in the Arctic: winners or losers under climate change and ocean acidification?

AbstractClimate change, ocean acidification (OA) and the subsequent changes in marine productivity may affect fisheries and eventually the whole economy in the Arctic. We analysed how changes in climate and ocean pH under scenarios of anthropogenic CO2 emissions are likely to affect the economics of marine fisheries in the Arctic. We applied a Dynamic Bioclimate Envelope Model (DBEM) and outputs from four different Earth System Models (ESMs) to project future changes in the distribution and maximum catch potential of exploited marine fishes and invertebrates. We projected that total fisheries revenue in the Arctic region may increase by 39% (14–59%) by 2050 relative to 2000 under the Special Reports on Emission Scenario (SRES) A2. Simultaneously, total fishing costs, fishers’ incomes, household incomes and economy‐wide impacts in the Arctic are also projected to increase. Climate change with OA is expected to reduce the potential increases in catch and the economic indicators studied herein. Although the projections suggest that Arctic countries are likely to be ‘winners’ under climate change in comparison with tropical developing countries, the effects of OA will lower the expected future benefits in the Arctic. The predicted impacts are likely to be conservative as we consider only the direct effects of OA on fishes and calcifiers, of which there are only a few in the Arctic. Results of this study would be useful for designing effective adaptation strategies to climate change and measures to mitigate the potential negative impacts of OA in the Arctic.

Region-based MTI: resolving geographic expansion in the Marine Trophic Index

The Marine Trophic Index (MTI), which tracks the mean trophic level of fishery catches from an ecosystem, generally, but not always, tracks changes in mean trophic level of an ensemble of exploited species in response to fishing pressure. However, one of the disadvantages of this indicator is that declines in trophic level can be masked by geographic expansion and/or the development of offshore fisheries, where higher trophic levels of newly accessed resources can overwhelm fishing-down effects closer inshore. Here, we show that the MTI should not be used without accounting for changes in the spatial and bathymetric reach of the fishing fleet, and we develop a new index that accounts for the potential geographic expansion of fisheries, called the region-based MTI (RMTI). To calculate the RMTI, the potential catch that can be obtained given the observed trophic structure of the actual catch is used to assess the fisheries in an initial (usu- ally coastal) region. When the actual catch exceeds the potential catch, this is indicative of a new fishing region being exploited. The MTI of the new region can then be calculated, and subsequent regions are determined in a sequential manner. This method improves upon the use of the Fish- ing-in-Balance (FiB) index in conjunction with the original MTI calculated over the whole time series because assumptions of fleet and stock stationarity over the entire time series and geo- graphic area are removed. We illustrate the utility of the RMTI with simulated examples and actual data, and generalize these results.

Fishing inside or outside? A case studies analysis of potential spillover effect from marine protected areas, using food web models

Marine protected areas (MPAs) are implemented worldwide as an efficient tool to preserve biodiversity and protect ecosystems. We used food web models (Ecopath and EcoTroph) to assess the ability of MPAs to reduce fishing impacts on targeted resources and to provide biomass exports for adjacent fisheries. Three coastal MPAs: Bonifacio and Port-Cros (Mediterranean Sea), and Bamboung (Senegalese coast), were used as case studies. Pre-existing related Ecopath models were homogenized and ecosystem characteristics were compared based on network indices and trophic spectra analyses. Using the EcoTroph model, we simulated different fishing mortality scenarios and assessed fishing impacts on the three ecosystems. Lastly, the potential biomass that could be exported from each MPA was estimated. Despite structural and functional trophic differences, the three MPAs showed similar patterns of resistance to simulated fishing mortalities, with the Bonifacio case study exhibiting the highest potential catches and a slightly inferior resistance to fishing. We also show that the potential exports from our small size MPAs are limited and thus may only benefit local fishing activities. Based on simulations, their potential exports were estimated to be at the same order of magnitude as the amount of catch that could have been obtained inside the reserve. In Port Cros, the ban of fishing inside MPA could actually allow for improved catch yields outside the MPA due to biomass exports. This was not the case for the Bonifacio site, as its potential exports were too low to offset catch losses. This insight suggests the need for MPA networks and/or sufficiently large MPAs to effectively protect juveniles and adults and provide important exports. Finally, we discuss the effects of MPAs on fisheries that were not considered in food web models, and conclude by suggesting possible improvements in the analysis of MPA efficiency.

Evaluation of three harvest control rules for Bigeye Tuna (Thunnus obesus) fisheries in the Indian Ocean

The stock of Bigeye tuna (Thunnus obesus) in the Indian Ocean supports an important international fishery and is considered to be fully exploited. The responsible management agency, the Indian Ocean Tuna Commission (IOTC), does not have an explicit management decision-making framework in place to prevent over-fishing. In this study, we evaluated three harvest control rules, i) constant fishing mortality (CF), from 0.2 to 0.6, ii) constant catch (CC), from 60000 to 140000 t, and iii) constant escapement (CE), from 0.3 to 0.7. The population dynamics simulated by the operating model was based on the most recent stock assessment using Stock Synthesis version III (SS3). Three simulation scenarios (low, medium and high productivity) were designed to cover possible uncertainty in the stock assessment and biological parameters. Performances of three harvest control rules were compared on the basis of three management objectives (over 3, 10 and 25 years): i) the probability of maintaining spawning stock biomass above a level that can sustain maximum sustainable yield (MSY) on average, ii) the probability of achieving average catches between 0.8 MSY and 1.0 MSY, and iii) inter-annual variability in catches. The constant escapement strategy (CE=0.5), constant fishing mortality strategy (F=0.4) and constant catch (CC=80000) were the most rational among the respective management scenarios. It is concluded that the short-term annual catch is suggested at 80000 t, and the potential total allowable catch for a stable yield could be set at 120000 t once the stock had recovered successfully. All the strategies considered in this study to achieve a ‘tolerable’ balance between resource conservation and utilization have been based around the management objectives of the IOTC.

Is a fish in hand worth two in the sea? Evidence from a stated preference study

The value anglers place on their fishing opportunities is critical information for fully informing marine policy within an economic efficiency framework. In this paper, we use data from a 2007 stated preference survey of anglers to estimate the value of catching Pacific halibut (Hippoglossus stenolepis), Chinook salmon (Oncorhynchus tshawytscha), and coho salmon (Oncorhynchus kisutch) off the coast of Southeast and Southcentral Alaska, the primary regions for saltwater sport fishing in the state. The data support a specification that differentiates between values for fish that are caught and kept, caught and released (due to a bag limit restriction), and potential catch (fish in excess of the number caught but within the bag limit). The results indicate that for single-day marine private boat fishing trips where one species is caught with catches less than or equal to the allowable bag (or take) limit, Southeast Alaska residents had mean values for fishing ranging from $248 to $313 (U.S. dollars), depending upon whether the fish was kept or released. Single-day private boat fishing trips in Southcentral Alaska were valued between $284 and $385 by Alaska residents. Among Alaska residents, mean values for charter fishing trips in Southcentral Alaska were between $228 and $328. Non-residents had much higher total values for the same fishing experiences, likely due to the fact that the trips are both less common and considerably more expensive to participate in given the travel costs to Alaska. Mean trip values ranged from $1849 to $2686 for charter fishing in Southeast Alaska and $1954 to $2819 in Southcentral Alaska. Non-resident and Alaska resident anglers generally had statistically-significant positive values for increases in number of fish caught and kept, potential catch, and fish size.

Using scenarios to project the changing profitability of fisheries under climate change

AbstractOver‐exploitation and economic underperformance are widespread in the world's fisheries. Global climate change is further affecting the distribution of marine species, raising concern for the persistence of biodiversity and presenting additional challenges to fisheries management. However, few studies have attempted to extend bioclimatic projections to assess the socio‐economic impacts of climate‐induced range shifts. This study investigates the potential implications of changes in relative environmental suitability and fisheries catch potential on UK fisheries by linking species distribution modelling with cost‐benefit analyses. We develop scenarios and apply a multimodel approach to explore the economic sensitivity of UK fisheries and key sources of uncertainty in the modelling procedure. We projected changes in maximum potential catch of key species and the resulting responses in terms of net present value (NPV) over a 45‐year period under scenarios of change in fuel price, discount rate and government subsidies. Results suggest that total maximum potential catch will decrease within the UK EEZ by 2050, resulting in a median decrease in NPV of 10%. This value decreases further when trends of fuel price change are extrapolated into the future, becoming negative when capacity‐enhancing subsidies are removed. Despite the variation in predictions from alternative models and data input, the direction of change in NPV is robust. This study highlights key factors influencing future profitability of UK fisheries and the importance of enhancing adaptive capacity in UK fisheries.