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Reconstructing historical baseline catches along Highway 101: U.S. West Coast marine fisheries, 1950-2017
Abstract
The United States of America, as most other countries, emphasizes commercial fisheries when reporting statistics to the Food and Agriculture Organization of the United Nations (FAO), and excludes data from other sectors, such as recreational fisheries. Our study is a first attempt to account comprehensively for all sources of total U.S. marine catches from the Exclusive Economic Zone waters along the West Coast of the continental USA from 1950-2017 in one dataset, i.e., excluding the states of Alaska and Hawaii. Total reconstructed catches for 1950-2017 were 1.2 times higher than the data reported by the USA to the FAO. Commercial landings dominated catches, with 65% from large-scale, industrial fisheries and 31% from small-scale, commercial fisheries. Recreational fisheries accounted for 4% of the total catch, after accounting for post-release mortality. Total catches were highest in 1950 at around 750,000 t and declined to 570,000 t by 2017. Internationally unreported discards increased from 24,000 t in 1950 to 86,000 t in 1989, but declined after the introduction of bycatch reduction devices to around 10,000 t⋅year ⁻¹ by the mid-2010s. Total catches by taxonomic category suggest a decline in the diversity in catches. Levels of reporting for total catches is excellent for recent decades, with around 95% of total catches accounted for by the mid-2010s, but around 40% of catches were missing from data reported to the FAO between the late 1960s and early 1990s. This discrepancy was largely driven by industrial catches of North Pacific hake (Merluccius productus) that were not in the officially reported data. Our results suggest that recreational fisheries and discards can make up a considerable component of total catches over time. We suggest that the USA include their recreational catch estimates in their annual data submission to the FAO, retroactively to 1950.
China has a number of fisheries management policies aimed at curbing the decline of fisheries resources. Due to the management subject is relatively unitary, we speculate that policies are constantly influencing each other, which results in system fault. To investigate the structural correlation between policies, a hybrid method comprising the probabilistic linguistic term set (PLTS), the Dempster–Shafer evidence theory (DST), and the decision-making trial and evaluation laboratory (DEMATEL) was proposed. First, the policy factors for China’s marine fisheries management are analyzed, and the PLTS is used to obtain the original data given by experts to describe the direct influence degree between each pair of policy factors. Then, all PLTSs are transferred to the basic probability assignment functions, and they are fused by Dempster’s rule to obtain the initial direct-relation (IDR) matrix. With the IDR matrix as inputs, the DEMATEL method was employed to identify the key policy factors. The results found that the prominence degrees of the two policies of output control were the highest, indicating that output control is the core policy type that can be critically linked to the effectiveness of policy system. Finally, the corresponding suggestions were put forward.
Recent literature on marine fish farming brands it as potentially compatible with sustainable resource use, conservation, and human nutrition goals, and aligns with the emerging policy discourse of ‘blue growth’. We advance a two-pronged critique. First, contemporary narratives tend to overstate marine finfish aquaculture’s potential to deliver food security and environmental sustainability. Second, they often align with efforts to enclose maritime space that could facilitate its allocation to extractive industries and conservation interests and exclude fishers. Policies and investments that seek to increase the availability and accessibility of affordable and sustainable farmed aquatic foods should focus on freshwater aquaculture.
Purpose of review:
This review brings together recent key research related to the role of fisheries as a source of nutrients to improve human health and discusses the implications of fisheries policy on food- and nutrient-security.
Recent findings:
Recent studies highlight the critical role of fisheries to support human nutrition, describing the nutrient composition of hundreds of species of fish, the global distribution of these fish, and the strategic role of fisheries in addressing micronutrient deficiencies. In many developing regions and emerging economies, fisheries can address malnutrition with local supplies of critical nutrients such as fatty acids, zinc, iron, calcium, and vitamins, making these accessible to low-income populations. However, this local potential is jeopardized by overfishing, climate change, and international trade, which reduce the local availability of nutritious and affordable fish in low-income countries, where they are most needed. This calls for policy reforms that shift management focus of fisheries as a commodity provider to a domestic public health asset to ensure food- and nutrient-security.
Commercial fisheries catches by countries are documented since 1950 by the Food and Agriculture Organization (FAO). Unfortunately, this does not hold for marine recreational catches, of which only few, if any, estimates are reported to FAO. We reconstructed preliminary estimates of likely marine recreational catches for 1950—2014, based on independent reconstructions for 125 countries. Our estimates of marine recreational catches that are retained and landed increased globally until the early-1980s, stabilized through the 1990s, and began increasing again thereafter, amounting to around 900,000 t·year−1 in 2014. Marine recreational catches thus account for slightly less than 1% of total global marine catches. Trends vary regionally, increasing in Asia, South America and Africa, while slightly decreasing in Europe and Oceania, and strongly decreasing in North America. The derived taxonomic composition indicates that recent catches were dominated by Sparidae (12% of total catches), followed by Scombridae (10%), Carangidae (6%), Gadidae (5%), and Sciaenidae (4%). The importance of Elasmobranchii (sharks and rays) in recreational fisheries in some regions is of concern, given the life-history traits of these taxa. Our preliminary catch reconstruction, despite high data uncertainty, should encourage efforts to improve national data reporting of recreational catches.
Nutrient content analyses of marine finfish and current fisheries landings show that fish have the potential to substantially contribute to global food and nutrition security by alleviating micronutrient deficiencies in regions where they are prevalent.
This contribution presents a synthesis, via a semilogarithmic regression, of estimates of the slow increase of technological efficiency, or "creep factor," as estimated by various authors for a number of demersal and pelagic fisheries. This factor is used in fisheries science to adjust for the gradual increase in the effectiveness of fishing gear resulting from the successive introduction of technological improvement to fishing gear and vessels. Altogether, 51 estimates of this creep factor, mostly around 2-4%/yr and covering periods from 4 to 129 yr, were assembled or newly calculated from secondary data and shown to decrease as the period covered increased. This finding is compatible with the hypothesis that creep factors are usually estimated and published to correct for the introduction of an effective new technology over a short period of time. We suggest that estimates obtained in this fashion cannot be applied to long-term analyses and propose instead our empirical relationship, derived from estimates of creep factor and the number of years covered in a study. Also, our study confirms that technology creep must be included in all analyses involving time series of fishing effort, particularly if they exceed one decade in temporal coverage.
Accurate historical data are useful for fisheries management and monitoring long-term changes in marine ecosystems. However, official catch statistics typically only include landings data from commercial fisheries and do not include other important sources of catch such as recreational fisheries, discards, or illegal fishing. Here, we estimate the major sources of marine withdrawals for fisheries in California, Oregon and Washington for the 1950-2010 period by including sources of typically unreported catch (such as discards and recreational fisheries) and by replacing gaps in the time series with actual estimates. The reconstructed catch was 750,000 t in 1950, just before the waning of the sardine fishery, and declined to 545,000 t by 2010, ranging between 380,000 t•year-1 and 640,000 t•year-1 from 1951-2009. Catches consisted of commercial landings (87%), followed by discards (8%) and recreational take (4%), and were 1.2 times the landings reported by NOAA/NMFS for the West Coast. As part of the Sea Around Us database definitions, we split the commercial catches into two fishing sectors: 'industrial' (being large-scale commercial) and 'artisanal' (being small-scale commercial). We hope the results presented here will help improve historic time series of catch and provide a better understanding of important changes that have occurred over the past 6 decades. We also hope that this study may shed some light on the extent of recreational fisheries and discards and will provide justification for continued monitoring of these sources of catch.
This paper re-evaluates the contributions to global food supplies of ‘aquatic animal-source food’ from aquaculture and capture fisheries, and ‘terrestrial animal-source food’ from livestock farming. Three common misunderstandings in the scientific and policy literature are addressed: (1) aquaculture was the fastest growing food production sector over the past three decades, (2) aquaculture has surpassed capture fisheries as the main source of fish for human consumption, and (3) production of aquatic animal-source foods has outstripped that of terrestrial animal-source food. These misunderstandings result partly from misuse of statistics: although possessing a relatively high annual growth rate in percentage terms, production of aquatic animal-source food increased from a much lower basal production level than the production of terrestrial animal-source food. Misunderstanding also arose partly from differences in the ways that aquatic and terrestrial animal-source food production are reported in global statistics. These differences systematically biased the reported gross weight of aquatic animal-source food produced globally upwards relative to that of terrestrial animal-source food. Comparing edible portions of aquatic and terrestrial animal-sources foods revealed the following three main points: first, although having a high annual growth rate in percentage terms, growth in the production of edible aquatic food has lagged far behind that of terrestrial meat by volume; second, capture fisheries still produce more edible aquatic food than aquaculture, and third, global production of beef exceeds that of farmed aquatic meat. Poultry is the largest animal-source food producing sector and is growing faster than aquaculture by volume.
Keywords: Aquaculture; Aquatic animal-source food; Fisheries; Food security; Livestock; Terrestrial animal-source food
Since 2014, the U.S. West Coast has experienced a sudden increase in reported whale entanglements with commercial fishing gear. The increase has been particularly acute in reported entanglements between Humpback whales (Megaptera novaeangliae) and commercial Dungeness crab gear. The current rate of entanglements is alarming and could trigger consequences for the responsible fisheries under the Marine Mammal Protection Act (MMPA) and Endangered Species Act (ESA); it seems likely that some change in the social-ecological status quo will be necessary to avoid significant harm to either the fishing community or the whale population. Here, we compare management alternatives to reduce entanglements, thereby reducing conflicts between whales and fishermen, scoring these alternatives according to estimated cost to fishermen, likely technical effectiveness, and anticipated reaction of fishermen in response to the change. We analyze these alternatives quantitatively using a Multi-Criterion Decision Analysis, and provide the analytical code as a decision-aid tool for managers and policy makers to use when contemplating changes to the West Coast commercial Dungeness fishery. We find a small number of high-ranking policy options; most prominently among these are Galvanic Timed Releases, which minimize the time that crab-pot lines are in the water and thus reduce the likelihood of entanglement. In addition, we include in an appendix a detailed list of regulations affecting the commercial Dungeness fishery, thereby providing both a substantive and procedural roadmap for reducing fishery-whale conflict.
The bias in catch time series data that occurs when improvements in fisheries catch reporting systems (e.g., consideration of a previously unmonitored fishery, or region) lead to an increase in current catches without the corresponding past catches being corrected retroactively, here called ‘presentist bias’ is described, and two examples, pertaining to Mozambique and Tanzania are given. This bias has the effect of generating catch time series at the aggregate that appear ‘stable’ or increasing when in fact catches are declining over time, with potentially serious consequences for the assessment of the status of national fisheries, or in interpreting the global landings data disseminated by the FAO. The presentist bias can be compensated for by retroactive national data corrections as done, e.g., through catch reconstructions.
Amidst overexploited fisheries and further climate related declines projected in tropical fisheries, marine dependent small-scale fishers in Southeast Asia face an uncertain future. Yet, small-scale fishers are seldom explicitly considered in regional fisheries management and their contribution to national fish supply tends to be greatly under-estimated compared to industrial fisheries. Lack of knowledge about the small-scale sector jeopardizes informed decision-making for sustainable ecosystem based fisheries planning and social development. We fill this knowledge gap by applying reconstructed marine fish catch statistics from Cambodia, Malaysia, Thailand, and Vietnam—countries of the Gulf of Thailand—from 1950 to 2013 to assess the relative contribution of small-scale and industrial fisheries to national food security. Reconstructed catches quantify reported and unreported fish catch from industrial, small-scale, and recreational fishing. We then conduct a comparative analysis of the degree to which the industrial and small-scale sectors support food security, by converting total catch to the portion that is kept for human consumption and that which is diverted to fishmeal for animal feed or other purposes. Total reconstructed marine fish catch from the four Southeast Asian countries totalled 282 million t from 1950 to 2013, with small-scale sector catches being underestimated by an average of around two times. When the amount of fish that is diverted to fishmeal is omitted, small-scale fishers contribute more food fish for humans than do industrial fisheries for much of the period until 2000. These results encourage regional fisheries management to be cognisant of small-scale fisheries as a pillar of socio-economic well-being for coastal communities.
As part of the global marine fisheries catch reconstruction project conducted by the Sea Around Us over the last decade, estimates were derived for discards in all major fisheries in the world. The reconstruction process derives conservative but non-zero time-series estimates for every fisheries component known to exist, and relies on a wide variety of data and information sources and on conservative assumptions to ensure comprehensive and complete time-series coverage. Globally, estimated discards increased from under 5 million t/year (t = 1,000 kg) in the early 1950s to a peak of 18.8 million t in 1989, and gradually declined thereafter to levels of the late 1950s of less than 10 million t/year. Thus, estimated discards represented between 10% and 20% of total reconstructed catches (reported landings + unreported landings + unreported discards) per year up to the year 2000, after which estimated discards accounted for slightly less than 10% of total annual catches. Most discards were generated by industrial (i.e. large-scale) fisheries. Discarding occurred predominantly in northern Atlantic waters in the earlier decades (1950s–1980s), after which discarding off the West Coast of Africa dominated. More recently, fleets operating in Northwest Pacific and Western Central Pacific waters generated the most discards. In most areas, discards consist essentially of marketable taxa, suggesting a combination of poor fishing practices and poor management procedures is largely responsible for the waste discarding represents. This is important in an era of increasing food security and human nutritional health concerns, especially in developing countries.
Comments are provided on several points in the 2016 State of the World Fisheries and Aquaculture produced by the Food and Agriculture Organization of the United Nations (FAO). It is shown that data assembled by FAO from submissions by countries suggest a “stable” trend mainly because the declining catches of a number of countries with reliable statistics is compensated for by unreliable statistics from countries where reporting increasing catches may be politically expedient, e.g., China, Myanmar. Also, concerns are raised as to why FAO chose to ignore the well-documented data ‘reconstruction’ process, which fills the gaps that exist in data reported by countries to FAO. It is being ignored despite its importance for governance and resource conservation being well known. This process and its findings could be used by FAO to encourage countries to improve their data reporting, including retroactive corrections. This is important in view of successive analyses of the status of fisheries resources undertaken by FAO (published in current and past SOFIAs) and also in modified form by the Sea Around Us. This suggests a degradation of marine fisheries, and, if trends continue, a crisis by mid-century. Finally, comments are presented on the proposition that aquaculture will overtake wild capture fisheries in terms of food production, notably because current aquaculture requires huge quantities of wild-caught fish as feed. Indeed, this emphasis on aquaculture-as-substitute for fisheries raises issues of food security and malnutrition in developing countries, from which much of the fish used as feed originates.
Christopher Golden and colleagues calculate that declining numbers of marine fish will spell more malnutrition in many developing nations.
Supplementary Table S1. Supplementary material
Fisheries data assembled by the Food and Agriculture Organization (FAO) suggest that global marine fisheries catches increased to 86 million tonnes in 1996, then slightly declined. Here, using a decade-long multinational 'catch reconstruction' project covering the Exclusive Economic Zones of the world's maritime countries and the High Seas from 1950 to 2010, and accounting for all fisheries, we identify catch trajectories differing considerably from the national data submitted to the FAO. We suggest that catch actually peaked at 130 million tonnes, and has been declining much more strongly since. This decline in reconstructed catches reflects declines in industrial catches and to a smaller extent declining discards, despite industrial fishing having expanded from industrialized countries to the waters of developing countries. The differing trajectories documented here suggest a need for improved monitoring of all fisheries, including often neglected small-scale fisheries, and illegal and other problematic fisheries, as well as discarded bycatch.
Tourism is vital to the economy of small island states like The Bahamas and is closely linked to fisheries. Fish is a protein source for tourists and residents, and both groups expect to catch and eat local fish. To adequately manage these dual demands, we need to know total removals of fish, as well as patterns of demand by tourists and residents in the past and present. Using a reconstruction approach, we performed a comprehensive accounting of fisheries catches in The Bahamas from commercial and noncommercial sectors for 1950-2010 and estimated the demand from tourism over the same period. Our results distinctly contrast with national data supplied to the Food and Agriculture Organization of the United Nations (FAO), which presents only commercial landings. Reconstructed total catches (i.e., reported catches and estimates of unreported catches) were 2.6 times the landings presented by the FAO for The Bahamas. This discrepancy was primarily due to unreported catches from the recreational and subsistence fisheries in the FAO data. We found that recreational fishing accounted for 55% of reconstructed total catches. Furthermore, 75% of reconstructed total catches were attributable to tourist demand on fisheries. Incomplete accounting for catches attributed to the tourist industry, therefore, makes it difficult to track potentially unsustainable pressures on fisheries resources. © 2016, National Marine Fisheries Service. All rights reserved.
We synthesize fisheries catch reconstruction studies for 25 Pacific island countries, states and territories, which compare estimates of total domestic catches with officially reported catch data. We exclude data for the large-scale tuna fleets, which have largely foreign beneficial ownership, even when flying Pacific flags. However, we recognize the considerable financial contributions derived from foreign access or charter fees for Pacific host countries. The reconstructions for the 25 entities from 1950 to 2010 suggested that total domestic catches were 2.5 times the data reported to FAO. This discrepancy was largest in early periods (1950: 6.4 times), while for 2010, total catches were 1.7 times the reported data. There was a significant difference in trend between reported and reconstructed catches since 2000, with reconstructed catches declining strongly since their peak in 2000. Total catches increased from 110,000 t yr−1 in 1950 (of which 17,400 t were reported) to a peak of over 250,000 t yr−1 in 2000, before declining to around 200,000 t yr−1 by 2010. This decrease is driven by a declining artisanal (small-scale commercial) catch, which was not compensated for by increasing domestic industrial (large-scale commercial) catches. The artisanal fisheries appear to be declining from a peak of 97,000 t yr−1 in 1992 to less than 50,000 t yr−1 by 2010. However, total catches were dominated by subsistence (small-scale, non-commercial) fisheries, which accounted for 69 % of total catches, with the majority missing from the reported data. Artisanal catches accounted for 22 %, while truly domestic industrial fisheries accounted for only 6 % of total catches. The smallest component is the recreational (small-scale, non-commercial and largely for leisure) sector (2 %), which, although small in catch, is likely of economic importance in some areas due to its direct link to tourism income.
Intergenerational loss of information about the abundance of exploited species can lead to shifting baselines, which have direct consequences for how species and ecosystems are managed. Historical data provide a means of regaining that information, but they still are not commonly applied in marine conservation and management. Omission of relevant historical information typically results in assessments of conservation status that are more optimistic, recovery targets that are lower, and fisheries quotas that are higher than if long-term data were considered. Here, we review data and methods that can be used to estimate historical baselines for marine species including bony fishes, sharks, turtles, and mammals, demonstrate how baselines used in management change when historical data are included, and provide specific examples of how data from the past can be applied in management and conservation including extinction risk assessment, recovery target setting, and management of data-poor fisheries. Incorporating historical data into conservation and management frameworks presents challenges, but the alternative—losing information on past population sizes and ecological variability—represents a greater risk to effective management of marine species and ecosystems.
Global marine fisheries are underperforming economically because of overfishing, pollution and habitat degradation. Added to these threats is the looming challenge of climate change. Observations, experiments and simulation models show that climate change would result in changes in primary productivity, shifts in distribution and changes in the potential yield of exploited marine species, resulting in impacts on the economics of fisheries worldwide. Despite the gaps in understanding climate change effects on fisheries, there is sufficient scientific information that highlights the need to implement climate change mitigation and adaptation policies to minimize impacts on fisheries.
Fisheries catches from Pacific Island coral reefs are rarely recorded in official statistics. Reconstruction of catch estimates with limited hard data requires interpo- lation and assumptions, justifiable only by the unsatis- factory alternative of continued substitution of zero catches, a common policy interpretation for 'no data'. Uncertainties associated with reconstructions are high, requiring conservative estimation. American Samoan domestic fisheries consist of an artisanal, small-boat sec- tor, whose commercial catches are reported, and a shore- based subsistence sector, with no regular reporting. Our catch reconstruction (with large pelagic species removed) suggested a 79% decrease in catches between 1950 (752 t) and 2002 (155 t). Accounting for rapid human population growth on the main island, the per capita catch rate may have declined from 36.3 kgÆperson 1 year 1 in 1950 to 1.3 kgÆperson 1 year 1 by 2002, while the catch rate for the inhabited outer islands has been independently re- ported as 58.6 kgÆperson 1 year 1 . Catch per area of coral reef (to 50-m depth) may have declined from 5.5 to 0.7 t km 2 year 1 for the main island, and from 9.1 to 4.9 t km 2 year 1 for the outer islands, for 1950 and 2002, respectively. Summed for 1950-2002, our recon- struction suggested a 17-fold difference between recon- structed estimates and reported statistics.
Marine fishes and invertebrates respond to ocean warming through distribution shifts, generally to higher latitudes and deeper waters. Consequently, fisheries should be affected by 'tropicalization' of catch (increasing dominance of warm-water species). However, a signature of such climate-change effects on global fisheries catch has so far not been detected. Here we report such an index, the mean temperature of the catch (MTC), that is calculated from the average inferred temperature preference of exploited species weighted by their annual catch. Our results show that, after accounting for the effects of fishing and large-scale oceanographic variability, global MTC increased at a rate of 0.19 degrees Celsius per decade between 1970 and 2006, and non-tropical MTC increased at a rate of 0.23 degrees Celsius per decade. In tropical areas, MTC increased initially because of the reduction in the proportion of subtropical species catches, but subsequently stabilized as scope for further tropicalization of communities became limited. Changes in MTC in 52 large marine ecosystems, covering the majority of the world's coastal and shelf areas, are significantly and positively related to regional changes in sea surface temperature. This study shows that ocean warming has already affected global fisheries in the past four decades, highlighting the immediate need to develop adaptation plans to minimize the effect of such warming on the economy and food security of coastal communities, particularly in tropical regions.
Fisheries catches from Pacific Island coral reefs are rarely recorded in official statistics. Reconstruction of catch estimates with limited hard data requires interpolation and assumptions, justifiable only by the unsatisfactory alternative of continued substitution of zero catches, a common policy interpretation for ‘no data’. Uncertainties associated with reconstructions are high, requiring conservative estimation. American Samoan domestic fisheries consist of an artisanal, small-boat sector, whose commercial catches are reported, and a shore-based subsistence sector, with no regular reporting. Our catch reconstruction (with large pelagic species removed) suggested a 79% decrease in catches between 1950 (752t) and 2002 (155t). Accounting for rapid human population growth on the main island, the per capita catch rate may have declined from 36.3kgperson−1year−1 in 1950 to 1.3kgperson−1year−1 by 2002, while the catch rate for the inhabited outer islands has been independently reported as 58.6kgperson−1year−1. Catch per area of coral reef (to 50-m depth) may have declined from 5.5 to 0.7tkm−2year−1 for the main island, and from 9.1 to 4.9tkm−2year−1 for the outer islands, for 1950 and 2002, respectively. Summed for 1950–2002, our reconstruction suggested a 17-fold difference between reconstructed estimates and reported statistics.
The Amerasian Arctic, covering northern Siberia (Russia), Arctic Alaska (USA), and the Canadian Arctic, extends over seven
coastal Large Marine Ecosystems and makes up the seasonally ice-free part of FAO Statistical Area 18 (Arctic Sea). Historically,
the harsh climate has limited marine fisheries (here excluding marine mammal hunting) to small-scale operations conducted
mainly in estuaries and river deltas. Most of the catches have traditionally not been reported to FAO, with the result that
total catch estimated here from 1950 to 2006 is 75 times higher than the sum of the catches reported for FAO 18 (Arctic).
Catches were reconstructed from data on fishing communities in Canada and Alaska, and from various government and non-government
sources for Siberia. Based on national data supplied to FAO since 1950, catches have been reported as 12,700t in toto (reported on behalf of the former Soviet Union). This compares with our reconstructed catches of over 950,000t, i.e., 770,000,
89,000, and 94,000t by Russia, USA, and Canada, respectively for the same time period. The reconstructed catch (mainly whitefishes
in Siberia, various salmonids in Alaska, and Arctic char in Canada) was 24,100tyear−1 in 1950, but declined to 10,200tyear−1 by the mid-2000s. Reasons for these trends are discussed by country, along with sources of uncertainty (particularly large
for Siberia). Catches were allocated to Large Marine Ecosystems to present ecosystem-relevant baselines for the impact of
fisheries on the Arctic, which can be expected to increase, as industrial fisheries move into a warming Arctic following the
invasion of boreal species, unless countries apply precautionary ecosystem-based management approaches.
KeywordsCatch reconstruction–Amerasian arctic–Small-scale fisheries
Biodiverse coastal zones are often areas of intense fishing pressure due to the high relative density of fishing capacity in these nearshore regions. Although overcapacity is one of the central challenges to fisheries sustainability in coastal zones, accurate estimates of fishing pressure in coastal zones are limited, hampering the assessment of the direct and collateral impacts (e.g., habitat degradation, bycatch) of fishing. We compiled a comprehensive database of fishing effort metrics and the corresponding spatial limits of fisheries and used a spatial analysis program (FEET) to map fishing effort density (measured as boat-meters per km²) in the coastal zones of six ocean regions. We also considered the utility of a number of socioeconomic variables as indicators of fishing pressure at the national level; fishing density increased as a function of population size and decreased as a function of coastline length. Our mapping exercise points to intra and interregional 'hotspots' of coastal fishing pressure. The significant and intuitive relationships we found between fishing density and population size and coastline length may help with coarse regional characterizations of fishing pressure. However, spatially-delimited fishing effort data are needed to accurately map fishing hotspots, i.e., areas of intense fishing activity. We suggest that estimates of fishing effort, not just target catch or yield, serve as a necessary measure of fishing activity, which is a key link to evaluating sustainability and environmental impacts of coastal fisheries.
Illegal and unreported fishing contributes to overexploitation of fish stocks and is a hindrance to the recovery of fish populations and ecosystems. This study is the first to undertake a world-wide analysis of illegal and unreported fishing. Reviewing the situation in 54 countries and on the high seas, we estimate that lower and upper estimates of the total value of current illegal and unreported fishing losses worldwide are between $10 bn and $23.5 bn annually, representing between 11 and 26 million tonnes. Our data are of sufficient resolution to detect regional differences in the level and trend of illegal fishing over the last 20 years, and we can report a significant correlation between governance and the level of illegal fishing. Developing countries are most at risk from illegal fishing, with total estimated catches in West Africa being 40% higher than reported catches. Such levels of exploitation severely hamper the sustainable management of marine ecosystems. Although there have been some successes in reducing the level of illegal fishing in some areas, these developments are relatively recent and follow growing international focus on the problem. This paper provides the baseline against which successful action to curb illegal fishing can be judged.
Dialogue on improving small-scale fisheries for food security tends to centre on developing countries due to the generally more acute socio-economic problems these countries face in meeting global Sustainable Development Goals. Current management approaches to improve small-scale fisheries thus tend to cater specifically to the context of developing country fishers. This inadvertently excludes the small-scale fisheries of developed countries from international dialogue, which is a missed opportunity given the insights that can be drawn from understanding progressive challenges that emerge as small-scale fisheries evolve through different stages of socio-economic development. Japan is a developed country whose small-scale fisheries cannot be ignored- yet, most international dialogue about Japanese fisheries centre on its industrial fisheries. Against this backdrop, we stress that it is essential to raise the profile of Japanese and other developed country small-scale fisheries in order to ensure that challenges and potential solutions to their future ecological and socio-economic sustainability are heard and included in the global small-scale fisheries dialogue.
Despite worldwide demand for tuna products and considerable conservation interest by civil society, no single global dataset exists capturing the spatial extent of all catches from fisheries for large pelagic species across all ocean basins. Efforts to spatially quantify the historical catch of global tuna fisheries have been restricted to the few taxa of major economic interest, creating a truncated view of the true extent of the fisheries for tuna and other large pelagic fishes. Individual Regional Fisheries Management Organizations (RFMOs) have given varying degrees of attention to minor taxa and non-target species only in more recent years. Here, we compiled and harmonized public datasets of nominal landed catches, as well as spatial data on reported catches of large pelagic taxa reported for the industrial tuna and large pelagic fisheries by tuna RFMOs for the last 60+ years. Furthermore, we provide a preliminary estimate of marine finfishes discarded by these fisheries. We spatialized these data to create a publicly available, comprehensive dataset presenting the historical reported landed catches plus preliminary discards of these species in space for 1950-2016. Our findings suggest that current public reporting efforts are insufficient to fully and transparently document the global historical extent of fisheries for tuna and other large pelagic fishes. Further harmonization of our findings with data from small-scale tuna fisheries could contribute to a fuller picture of global tuna and large pelagic fisheries.
We estimated condition-specific survival rates of gray triggerfish (Balistes capriscus) using a tag-recapture approach and extrapolated these values to produce an overall discard survival estimate for the US South Atlantic recreational hook-and-line fishery. Tag return rates of fish tagged at the seafloor using SCUBA served as a reference for return rates of fish tagged at the surface. We examined the validity of gross necropsy as a proxy for survival by identifying likely causes of discard mortality. Best-condition surface-released fish (no external trauma) had an estimated mean proportional survival of 0.39 (95% confidence interval 0.28, 0.55). For gray triggerfish exhibiting visible trauma, estimated survival was 0.24 (0.10, 0.60). Floating fish had a survival rate of zero. The necropsy-based estimate of gray triggerfish lacking organ displacement closely matched the tag-based estimate of survival. Mean estimated discard survival across all depths for North Carolina was 0.35 (0.10, 0.59) and for Florida was 0.34 (0.08, 0.59). These results have implications for gray triggerfish management because our estimate of discard survival is substantially lower than previously assumed and for future discard survival research given our findings with gross necropsies.
Marine fisheries target and catch fish both for direct human consumption (DHC) as well as for fishmeal and fish oil, and other products. We derived the fractions used for each for 1950–2010 by fishing country, and thus provide a factual foundation for discussions of the optimal use of fisheries resources. From 1950 to 2010, 27% (~20 million tonnes annually) of globally reconstructed marine fisheries landings were destined for uses other than DHC. Importantly, 90% of fish destined for uses other than DHC are food-grade or prime food-grade fish, while fish without a ready market for DHC make up a much smaller proportion. These findings have implications for how we are using fish to feed ourselves or, more appropriately, how we are not using fish to feed ourselves.
Nearshore fisheries in the tropical Pacific play an important role, both culturally and as a reliable source of food security, but often remain under-reported in statistics, leading to undervaluation of their importance to communities. We re-estimated nonpelagic catches for Guam and the Commonwealth of the Northern Mariana Islands (CNMI), and summarize previous work for American Samoa for 1950-2002. For all islands combined, catches declined by 77%, contrasting with increasing trends indicated by reported data. For individual island entities, re-estimation suggested declines of 86%, 54%, and 79% for Guam, CNMI, and American Samoa, respectively. Except for Guam, reported data primarily represented commercial catches, and hence under-represented contributions by subsistence and recreational fisheries. Guam's consistent use of creel surveys for data collection resulted in the most reliable reported catches for any of the islands considered. Our re-estimation makes the scale of under-reporting of total catches evident, and provides valuable baselines of likely historic patterns in fisheries catches.
The mortality of discarded fish bycatch is an important issue in fisheries management and, because it is generally unmeasured, represents a large source of uncertainty in estimates of fishing mortality worldwide. Development of accurate measures of discard mortality requires fundamental knowledge, based on principles of bycatch stressor action, of why discarded fish die. To date, discard mortality studies in the field have focused on capture stressors. Recent laboratory discard experiments have demonstrated the significant role of environmental factors, size- and species-related sensitivity to stressors, and interactions of stressors, which increase mortality. In addition, delayed mortality was an important consideration in experimental design. The discard mortality problem is best addressed through a combination of laboratory investigation of classes of bycatch stressors to develop knowledge of key principles of bycatch stressor action and field experiments under realistic fishing conditions to verify our understanding and make predictions of discard mortality. This article makes the case for a broader ecological perspective on discard mortality that includes a suite of environmental and biological factors that may interact with capture stressors to increase stress and mortality.La mortalité des prises accessoires rejetées à l'eau est une question d'importance dans la gestion des pêches; parce qu'elle est rarement mesurée, elle représente une source considérable d'incertitude dans les estimations de la mortalité due à la pêche à l'échelle mondiale. L'élaboration de mesures précises de la mortalité des prises accessoires nécessite des connaissances fondamentales sur les causes de cette mortalité basées sur les modes d'action des facteurs de stress. À ce jour, les études se sont concentrées sur les stress reliés à la capture. Des études récentes en laboratoire ont souligné le rôle significatif des facteurs de l'environnement, de la sensibilité au stress spécifique à la taille et à l'espèce et des interactions entre les facteurs de stress, qui accroissent tous la mortalité. De plus, la mortalité retardée est un élément important du plan d'expériences. La meilleure façon d'aborder le problème de la mortalité des prises accessoires est par une combinaison d'études de laboratoire des différentes classes de facteurs de stress pour obtenir des connaissances sur les principes fondamentaux de leur mode d'action et par des expériences sur le terrain dans des conditions de pêche réalistes pour vérifier ces connaissances et faire des prédictions sur la moralité. Il faut donc utiliser dans l'étude de la mortalité des prises accessoires une perspective écologique élargie qui considère une série de facteurs environnementaux et biologiques qui peuvent interagir avec les facteurs de stress lors de la capture pour accroître le stress et la mortalité.[Traduit par la Rédaction]
The assumption that animals released from fishing gears survive has frequently been scrutinized by researchers in recent years. Mortality estimates from these research efforts can be incorporated into management models to ensure the sustainability of fisheries and the conservation of threatened species. Post-release mortality estimates are typically made by holding the catch in a tank, pen or cage for short-term monitoring (e.g. 48 h). These estimates may be inaccurate in some cases because they fail to integrate the challenges of the wild environment. Most obvious among these challenges is predator evasion. Stress and injury from a capture experience can temporarily impair physiological capacity and alter behaviour in released animals, a period during which predation risk is likely elevated. In large-scale commercial fisheries, predators have adapted their behaviour to capitalize on impaired fishes being discarded, while in recreational catch-and-release fisheries, exercise and air exposure can similarly impede the capacity for released fish to evade opportunistic predators. Owing to the indirect and often cryptic nature of this source of mortality, very few studies have attempted to document it. A survey of the literature demonstrated that <2% of the papers in the combined realms of bycatch and catch-and-release have directly addressed or considered post-release predation. Future research should combine field telemetry and laboratory studies using both natural and simulated predation encounters and incorporate physiological and behavioural endpoints. Quite simply, predation is an understudied and underappreciated contributor to the mortality of animals released from fishing gears.
With data series extending for 60 years, including catch data for almost 1850 species items, and reflecting geo-political, historical and natural events, the FAO capture database provides a service to the community interested in fishery information. Over 600 articles from refereed journals cited the database in the last 15 years. Species included grew significantly in the last decade and an analysis of annual reporting showed more timely data submissions, although the number of non-reporting countries remained stable throughout the years. An evaluation of data quality found over half developing countries reporting inadequately but also one-fourth of reports by developed countries were not satisfactory. This article also provides meta information on historical developments, data sources and coverage, and advice on what should be kept in mind when using the database for trend studies.
Since 2006, the IPHC stock assessment has been Þ tted to a coastwide dataset to estimate total exploitable biomass. Coastwide exploitable biomass at the beginning of 2010 is estimated to be 334 million pounds. The assessment revised last year's estimate of 325 million pounds at the start of 2009 downwards to 291 million pounds and projects an increase of 14% over that value to arrive at the 2010 value of 334 million pounds. The downward revision is part of a still present, but relatively modest, retrospective behavior shown in the model. At least part, if not most, of the downward revision for 2009 is believed to be caused by the ongoing decline in size at age, which continues for all ages in all areas. Just as last year, projections based on the currently estimated age compositions suggest that the exploitable and female spawning biomasses will increase over the next several years as a sequence of strong year classes recruit to the O32 component of the population. Trawl estimates of abundance were assembled this year and are comparable to the assessment estimates. The coastwide exploitable biomass was apportioned among regulatory areas in accordance with survey estimates of relative abundance, modiÞ ed by 1) adjustment factors for hook competition, station depth distribution, and timing of the annual setline survey; 2) equal (1:1:1) and reverse (2:2:1) weighting of the three most recent survey years; and 3) weighting with historical shares in a 2:1 ratio with the survey index receiving the larger weight. These factors resulted in 32 different apportionment schemes.
The mortality of discarded fish bycatch is an important issue in fisheries management and, because it is generally unmeasured, represents a large source of uncertainty in estimates of fishing mortality worldwide. Development of accurate measures of discard mortality requires fundamental knowledge, based on principles of bycatch stressor action, of why discarded fish die. To date, discard mortality studies in the field have focused on capture stressors. Recent laboratory discard experiments have demonstrated the significant role of environmental factors, size- and species-related sensitivity to stressors, and interactions of stressors, which increase mortality. In addition, delayed mortality was an important consideration in experimental design. The discard mortality problem is best addressed through a combination of laboratory investigation of classes of bycatch stressors to develop knowledge of key principles of bycatch stressor action and field experiments under realistic fishing conditions to verify our understanding and make predictions of discard mortality. This article makes the case for a broader ecological perspective on discard mortality that includes a suite of environmental and biological factors that may interact with capture stressors to increase stress and mortality.
This paper discusses fish consumption and preference patterns for fish species by income groups, and by urban/rural divide in Bangladesh, China, India, Indonesia, the Philippines, Thailand, and Vietnam. The analysis is based on primary data collected by the WorldFish Center and its partner institutes by means of a survey of 5,931 households in the selected countries. The FAO database and other published materials were also used to analyze trends in fish consumption. Freshwater fish species constitute a major share in total per capita fish consumption in most of these countries. Pelagic and demersal marine fish are the main contributor to per capita total fish consumption in the countries with longer coastal boundaries (such as Indonesia, the Philippines and Thailand), and in the coastal regions within each country. Results suggest that fish contributes between 15% and 53% of the total animal protein intake in these countries. Fish consumption varies widely with economic position of the households, in terms of both per capita consumption and type of fish species. Per capita fish consumption increases with increase in income. The share of fish protein in total animal protein expenditure is higher for lower income groups, demonstrating their dependence on fish as a source of animal protein. Poor people consume mostly low-price fish and rich people spend a significant portion of their fish budget on expensive fish. Per capita fish consumption is substantially higher in rural areas than in urban areas.
Previous projection of climate change impacts on global food supply focuses solely on production from terrestrial biomes, ignoring the large contribution of animal protein from marine capture fisheries. Here, we project changes in global catch potential for 1066 species of exploited marine fish and invertebrates from 2005 to 2055 under climate change scenarios. We show that climate change may lead to large-scale redistribution of global catch potential, with an average of 30–70% increase in high-latitude regions and a drop of up to 40% in the tropics. Moreover, maximum catch potential declines considerably in the southward margins of semienclosed seas while it increases in poleward tips of continental shelf margins. Such changes are most apparent in the Pacific Ocean. Among the 20 most important fishing Exclusive Economic Zone (EEZ) regions in terms of their total landings, EEZ regions with the highest increase in catch potential by 2055 include Norway, Greenland, the United States (Alaska) and Russia (Asia). On the contrary, EEZ regions with the biggest loss in maximum catch potential include Indonesia, the United States (excluding Alaska and Hawaii), Chile and China. Many highly impacted regions, particularly those in the tropics, are socioeconomically vulnerable to these changes. Thus, our results indicate the need to develop adaptation policy that could minimize climate change impacts through fisheries. The study also provides information that may be useful to evaluate fisheries management options under climate change.
Correct catch data are necessary for age-structured assessment models. Those data may be biased among other reasons due to fishing practices such as discarding or selection by gear and subsequent escapee mortality. In a number of fisheries juveniles make a large fraction of catches while their survival is low. We applied length-specific selection and escapee mortality functions to estimate “underwater discarding” and the actual total removals from the herring (Clupea harengus L.) stock in the northern Baltic Sea. Contemporarily an array of fleet selection scenarios was investigated to estimate the impact of underwater discarding on perceived stock dynamics. The analysis showed that in ages 0 and 1 year herring are discarded underwater in larger numbers than landed. Unaccounted mortality involves a marked seasonal pattern because the growth rate of immature herring is high. During the first quarter of the year the first fully recruited age group is 1 year instead of 2 years as indicated by catch samples. The effect of fishing induced mortality decreases as a function of age and size so that the impact on estimated recruitment and fishing mortality at age 1 year is considerable, but irrelevant at age 2 years and older. The actual fishing mortality at age 1 year is estimated to be more than twice higher than estimates of F based on the unadjusted data. The practical effect of underwater discarding on evaluation of stock status, the stock–recruitment function, and reference points is minor. However, changes in codend mesh size, induced by management actions or fishing strategies, should be recognized and their effects considered in stock assessment, in short term forecasts, and in management advice.
Derelict fishing gear remains in the marine environment for years, entangling, and killing marine organisms worldwide. Since 2002, hundreds of derelict nets containing over 32,000 marine animals have been recovered from Washington’s inland waters. Analysis of 870 gillnets found many were derelict for years; most were recovered from northern Puget Sound and high-relief rocky habitats and were relatively small, of recent construction, in good condition, stretched open, and in relatively shallow water. Marine organisms documented in recovered gillnets included 31,278 invertebrates (76 species), 1036 fishes (22 species), 514 birds (16 species), and 23 mammals (4 species); 56% of invertebrates, 93% of fish, and 100% of birds and mammals were dead when recovered. For all taxa, mortality was generally associated with gillnet effectiveness (total area, age and condition, and suspension in the water). Mortality from derelict fishing gear is underestimated at recovery and may be important for species of economic and conservation concern.
The bottom-fish stocks of the Main Hawaiian Islands (MHI) are intensively fished, both commercially and recreationally. Recent assessments of the Bottomfish Management Unit Species (BMUS) complex suggested overfishing, and expressed concerns about missing non-commercial data. We used reported commercial time-series data and estimation ratios to indirectly estimate non-commercial catches for non-pelagic species (i.e., excluding tuna and billfishes) for 1950–2005. Using adjustment ratios, we also accounted for commercial under-reporting, which suggested that total commercial non-pelagic catches were 28–128% higher than reported commercial catches for any given year. Estimated non-commercial catches for 1950–2005 were 2.1 times higher than reported commercial catches. Reported catches underestimated likely total catches (reported and un-reported commercial plus non-commercial) of non-pelagic species and BMUS components for 1950–2005 by a factor of 3.9 and 2.9, respectively. We incorporated the reconstructed BMUS non-commercial catches into stock assessments of the officially reported commercial BMUS catches via a Schaefer production model. Total catch increased by 2.5–3.5 times with the addition of non-commercial BMUS catch estimates, which in turn increased model estimates of MSY and carrying capacity (k) by approximately four times compared to analyses with reported commercial data alone. As the CPUE data lacked information to resolve the confounding between large, unproductive and small, productive stocks, an informative prior was used for fishing mortality rate to attain MSY (FMSY). To address uncertainty in key management parameters, independent estimates of exploitation rate, or fisheries independent estimates of abundance, and informative trends in recreational effort or catches are required.
The requirement, in 2003, that trawl vessels fishing for ocean shrimp (Pandalus jordani) use bycatch reduction devices (BRDs) has reduced fish bycatch by between 66% and 88% from historical (pre-BRD) levels. Prior to BRD requirements, bycatch was composed by weight mostly of adult and juvenile Pacific hake (Merluccius productus), various smelts (Osmeridae), yellowtail rockfish (Sebastes flavidus), sablefish (Anoplopoma fimbria) and lingcod (Ophiodon elongatus) and ranged from 32% to 61% of the total catch by weight. By 2005, BRD use had reduced fish bycatch to approximately 7.5% of total catch, composed mostly of juvenile Pacific hake, slender sole (Eopsetta exilis), smelts, rex sole (Errex zachirus) and juvenile rockfish (Sebastes). BRD requirements have eliminated marketable-sized fish from the catch, changing the economic incentives in the fishery to favor the use of more efficient BRDs. Based on Oregon data, from 2002 to 2005 the use of soft-panel BRDs declined and the use of more efficient rigid-grate BRDs increased to 97% of all trips. Over this same period, mean bar spacing in rigid-grate BRDs declined from 43 to 32 mm, also contributing to BRD efficiency. Data collected from a trawl experiment testing a rigid-grate BRD with 19-mm bar spacing suggest that bycatch in the ocean shrimp fishery can be reduced further, perhaps below 5% of total catch.
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Derelict fishing gear persists for decades and impacts marine species and underwater habitats. Agencies and organizations are removing significant amounts of derelict gear from marine waters in the United States. Using data collected from repeated survey dives on derelict gillnets in Puget Sound, Washington, we estimated the daily catch rate of a given derelict gillnet, and developed a model to predict expected total mortality caused by a given net based on entanglement data collected upon its removal. We also generated a cost:benefit ratio for derelict gear removal utilizing known true costs compared to known market values of the resources benefiting from derelict gear removal. For one study net, we calculated 4368 crab entangled during the impact lifetime of the net, at a loss of 19,656 dollars of Dungeness crab to the commercial fishery, compared to 1358 dollars in costs to remove a given gillnet, yielding a cost:benefit ratio of 1:14.5.