Small-scale Arctic charr Salvelinus alpinus fisheries in Canada's Nunavut: management challenges and options

The Arctic charr Salvelinus alpinus is a diverse and abundant resource in Canada's Nunavut. The anadromous form is primarily targeted by exploitation in small-scale fisheries. The continued importance of subsistence fisheries and growing interest in further developing commercial fisheries underline the need for proper management of S. alpinus in northern Canada. This paper presents the current state of S. alpinus fisheries in Nunavut and related management challenges. An alternate framework for assessment using life-history information as it determines stock productivity and resilience to harvesting is presented. This framework combines (1) a risk assessment tool [productivity-susceptibility analysis (PSA)] to evaluate the relative vulnerability of S. alpinus stocks to harvest and (2) a conceptual model for quantitative assessment to determine sustainable harvest levels. Diversity in S. alpinus life history and contrast in vulnerability scores derived from PSA assessment are demonstrated for a sample of 86 anadromous stocks from throughout Nunavut. These data provide evidence in support of an alternate strategy for assessment permitting to integrate diversity in S. alpinus life history for improved generalization and representativeness. Salvelinus alpinus fisheries in Arctic regions exemplify the need for stock assessment and management alternatives to ensure fish conservation in remote, sensitive ecosystems and in data-poor circumstances.     

Stock information requirements for quota management systems in commercial fisheries

Economic inefficiency and other problems associated with managing fisheries through restrictions on fishing times, places and gear have led to development of management systems based on individual fishers' quotas. But this shift from input controls to output controls calls for much more accurate and timely stock assessments. The risk of stock collapse resulting from overfishing, coupled with growing pressure for low-risk resource management policies, call for conservative quota-setting in the face of uncertain stock information. Under existing assessment systems, quotas may need to be so conservative that foregone catches could wipe out the economic gains from quota management. This problem might be overcome by taking advantage of the incentives of quota-holders to contribute to, and invest in, the gathering of information to improve stock assessments.     

Lessons for stock assessment from the northern cod collapse

Fisheries assessment scientists can learn at least three lessons from the collapse of the northern cod off Newfoundland: (1) assessment errors can contribute to overfishing through optimistic long-term forecasts leading to the build-up of overcapacity or through optimistic assessments which lead to TACs being set higher than they should; (2) stock size overestimation is a major risk when commercial catch per effort is used as an abundance trend index, so there is continued need to invest in survey indices of abundance trend no matter what assessment methodology is used; and (3) the risk of recruitment overfishing exists and may be high even for very fecund species like cod. This implies that harvest rate targets should be lower than has often been assumed, especially when stock size assessments are uncertain. In the end, the high cost of information for accurate stock assessment may call for an alternative approach to management, involving regulation of exploitation rate via measures such as large-scale closures (refuges) that directly restrict the proportion of fish available to harvest. Development of predictive models for such regulatory options is a major challenge for fisheries assessment science.     

The summer flounder chronicles III: struggling with success, 2011–2016

The summer flounder or fluke, Paralichthys dentatus, supports the most important commercial and recreational flatfish fisheries of the U.S. Atlantic coast. The stock and fisheries range from Massachusetts to North Carolina. The assessment and management of the summer flounder has been contentious since 1989, when a joint Atlantic States Marine Fisheries Commission/Mid-Atlantic Fishery Management Council Fishery Management Plan was implemented. Two previous papers recounted how fishing mortality on the summer flounder stock had decreased by 2010 to its lowest level in over 30 years, with stock biomass at its highest since the stock assessments began in the 1960s. Since 2010, the most important issues and controversies for summer flounder have included: (a) debate over the nature and causes of the observed changes in the spatial distribution of summer flounder and potential impacts for science and management, (b) the re-emergence of retrospective error in the assessment modeling results affecting the evaluation of stock status and the reliability of catch forecasts, (c) scientific and political debate over the necessity of including sex structure in the summer flounder assessment, and (d) the ongoing changes in the ‘tools’ used for catch regulation and allocation that attempt to effectively control fishing mortality while accounting for changes in spatial distribution. This work chronicles how summer flounder serves as a case study of the increasing ‘politicalization’ of fishery science and management, as the actions for summer flounder taken in response to the media commentary and ensuing political pressure have influenced U.S. national fisheries science, management strategy, and law.     

Longtail tuna,Thunnus tonggol (Bleeker, 1851): a global review of population dynamics,ecology, fisheries,and considerations for future conservation and management

Longtail tuna (Thunnus tonggol) is a neritic species that supports commercial, artisanal and recreational fisheries throughout the Indo-Pacific region. Historically receiving little attention by commercial fisheries, the global annual catch of longtail tuna has steadily risen from around 30,000 t in the early 1980s to exceeding 200,000 t since 2004, reaching a peak of 291,264 t in 2007, and was 281,613 t in 2017. Catches of longtail tuna in the Indian Ocean now exceed catches of principal commercial target species, such as albacore and bigeye tunas. A sequence of stock assessments undertaken throughout the species’ range since the late 1980s persistently indicated that at least three of the four stocks defined in this paper are likely to have been, and most likely are currently, subject to overfishing and overfished as a result of excess fishing effort on this relatively slow-growing and long-lived tuna species. As the spawning biomass of principal tuna target species continue to decline in both the Indian and western and central Pacific Oceans, the increasing catches of longtail tuna, other neritic tunas, and seerfishes is worrisome. Few conservation and management measures (CMMs) are currently in place specifically for longtail tuna, although in recent years some coastal States, Regional Fishery Bodies, and tuna Regional Fisheries Management Organisations have begun to develop initiatives to improve the catch and biological data quality for longtail tuna and sympatric species of neritic tunas and tuna-like species. This paper provides a global review of biological, ecological and fishery information to provide researchers, fishery managers and policy makers with the most current information from which to begin to guide future stock assessment and the development of CMMs for longtail tuna.

     

Trade-Based Estimation of Bluefin Tuna Catches in the Eastern Atlantic and Mediterranean, 2005–2011

The Eastern Atlantic and Mediterranean stock of Bluefin tuna Thunnus thynnus (BFTE) has long been considered overfished and at risk of collapse. Although ICCAT quotas for this stock have decreased considerably over the past years, uncertainty exists about the degree of catch beyond this quota. The extent of such catch is an important piece of information in stock assessment models as well as being an indicator of the effectiveness of fisheries management. We present a model using Bluefin tuna trade data to infer actual catches. Basing our calculations on 25 countries involved in BFTE trade, we estimate that between 2005 and 2011, allowable quotas were exceeded by 44 percent. This gap between catch and quotas has slightly increased over past years, leading to estimated excess catches of 57 percent for the period between 2008 and 2011. To improve assessments, preparation and design of BFTE management, we suggest that the estimated total removals reported in this paper be included in stock assessment models for BFTE. An implication of our findings is that ICCAT member states should take stronger measures to monitor and enforce compliance with quotas.     

Managing the fisheries by social engineering: a re-evaluation of the methods of stock assessment

This paper criticises the management of the world's fisheries that are based upon the use of 'positive' predictions derived from fisheries models, an instrumentalist approach which is illustrated by the practical application of Graham-Schaefer models constructed according to the verificationist's view of science. Instrumentalism is attractive for stock assessment because it appears to meet the need to overcome barriers within fisheries science to the deduction of specific predictions from universal laws. Through the construction of empirical models, existential predictions are produced which ape the specific predictions of the physical sciences and are of no more value in the management of the world's fisheries than the magic spells of witch doctors. To be contrasted with instrumentalism's prophetic use of 'positive' predictions, Karl Popper advocated a realist approach in which theoretical models help us gain factual information about the real-world in the form of what cannot be achieved : 'negative' explanatory predictions produced by models constructed according to the falsificationist's view of science and illustrated by the practical application of theoretical Gordon-Schaefer fisheries models.
The absence within fisheries stock assessment of a suitable alternative to instrumentalism comprises a widespread methodological lacuna. It is proposed that Popper's technological social science, designed to solve problems of social tradition of which overfishing is an example, would fill this lacuna. This technology would employ the services of a social engineer, a modern fisheries manager , who would use the pre-scientific method of trial and error and the negative guidance of bold pattern predictions to re-evaluate the institutions of fisheries management.     

How have spawning ground investigations of the Japanese eel Anguilla japonica contributed to the stock enhancement?

After Schmidt’s discovery of the spawning area of the Atlantic eels Anguilla anguilla and A. rostrata, the search for the Japanese eel A. japonica began in the Pacific Ocean. In 1991, the spawning area of the Japanese eel was determined to be the western North Pacific. Because of enthusiastic research, eggs and maturing eels have been collected in the Japanese eel. These findings are the first for one of the 19 freshwater eels. The population sizes of the Japanese and Atlantic eels are linearly decreasing. Thus, these eel population sizes are considered outside of safe biological limits, and the current fisheries are not sustainable. Artificial propagation has not yet succeeded for the freshwater eels. Stock assessment and management of the European eel have received increasing attention; however, such assessments and management of the Japanese eel have not yet been seriously considered. This paper is an overview of the results of intensive spawning ground investigations of the Japanese eel and describes how the outcomes of these studies have contributed not only to biological interests but also to stock enhancement. During the past 20 years of expeditions, noticeable findings have only been collected for wild eggs and mature adult specimens in spite of the expenditure of large research grants and the large amounts of time invested. The outcomes throughout an expedition do not necessarily contribute to the development and improvement of artificial breeding techniques and stock enhancement. Thus, eel research should be more focused on the studies related to eel stock management.     

Coral reef fisheries stock assessment

Summary Although all fisheries are multispecies and spatially heterogeneous, coral reef fisheries are an extreme in both respects. The two main approaches to stock assessment have been either to consider individual species separately or to lump all species together. Both are limited in their predictive power. The lack of ecological knowledge and the large number of parameters required make methods based on single species often impractical or expensive. However, where the appropriate information is available, ecological studies do not provide significant improvements on yield-per-recruit or surplus yield models currently used.Alternative community models based on aggregates of species lack predictive power, empirical support and relative data. Models are further limited because they do not address various economic aspects, fish movement and recruitment, all of which must be spatially resolved. However, the ECOPATH model, based on trophic compartments, represents a new approach useful to multispecies assessment, and the only way at present to include predation in stock models. In practice the data available will be the most important factor in the choice of stock assessment model.The major concern for management of many coral reefs is conservation of the habitat and stocks. In some cases this has been achieved with little reference to stock assessment, by using community management and closed areas, which are receiving increasing support. However, once the objective of conservation is achieved, stock assessment should have an important role in improving the economic performance of the fisheries. The wider problems of management have no simple solutions, but managers should look to adaptive management, designing their own experiments to choose between management models.     

Shared Stocks of Snappers (Lutjanidae) in Australia and Indonesia: Integrating Biology, Population Dynamics and Socio-Economics to Examine Management Scenarios

Joint Australia–Indonesia scientific workshops on the fisheries of the Arafura Sea, held in 1992 and 1994, concluded that the two countries might share stocks of the red snappers Lutjanus malabaricus and L. erythropterus and the gold-band snapper Pristipomoides multidens. At that time, no information concerning stock structure, distribution and movements of these species was available. Moreover, data on the population biology and on commercial catches were inadequate. Such data are crucial for stock assessment and for managing the stocks. Clearly, if the stocks being fished were shared, joint management would be appropriate. In order to answer the questions related to managing shared stocks, a collaborative research project was initiated by Australia (CSIRO as the lead agency) and Indonesia in 1999. The objectives were firstly, to describe the population dynamics, stock structure and biology of snappers relevant to the management of stocks shared between Australian and Indonesian fisheries; secondly, to characterize the social and financial structures of the Indonesian fishery so they could be taken into account in the development of management strategies; and thirdly, to explore ways of developing complementary management for the long term sustainability of the snapper fisheries. This project finished in 2003 and in this paper we bring together the results of the biological, genetic, population dynamics and socioeconomic research in relation to managing shared stocks in the context of managed versus unmanaged fisheries, small scale and industrial fisheries, and in both developed and developing country regulatory environments. Severe data limitations necessitated an innovative approach making use of comparative analyses, often data-poor values, and the drawing together of fishery dependent and independent data to evaluate the status of the stocks.     

The summer flounder chronicles II: new science,new controversy, 2001–2010

The summer flounder, or fluke, Paralichthys dentatus, supports the most important commercial and recreational flatfish fisheries of the US Atlantic coast. The stock and fishery range from Massachusetts to North Carolina. The assessment and management of the summer flounder fishery has been very contentious since implementation of the joint Atlantic States Marine Fisheries Commission/Mid-Atlantic Fishery Management Council Fishery Management Plan (FMP) in 1989, when the poor status of the summer flounder stock was evident to scientists, managers, and fishermen. Management efforts to control fishing mortality in the face of increasing stock abundance and competing demand for fish from both the commercial and recreational sectors continue to evoke the question of “How much fish is enough?” to provide for long-term sustainability. In spite of the numerous controversies, however, by 2010 the fishing mortality on summer flounder had declined to its lowest level in at least 30 years, and summer flounder stock biomass was the highest since the stock assessments began in the 1960s. From a scientific perspective, future assessments need to: (a) better account for the uncertainty resulting from “internal model” retrospective error, (b) better integrate environmental, ecological, and other non-traditional calibration indices into the modeling framework, and (c) better discern summer flounder stock-recruitment dynamics by considering covariates such as environmental factors and predator/prey abundance. Initiatives are underway to acquire improved fishery and biological data to allow the assessments to better reflect the true “state of nature.”     

The Conservation and Management of Tunas and Their Relatives: Setting Life History Research Priorities

Scombrids (tunas, bonitos, Spanish mackerels and mackerels) support important fisheries in tropical, subtropical and temperate waters around the world, being one of the most economically- and socially-important marine species globally. Their sustainable exploitation, management and conservation depend on accurate life history information for the development of quantitative fisheries stock assessments, and in the fishery data-poor situations for the identification of vulnerable species. Here, we assemble life history traits (maximum size, growth, longevity, maturity, fecundity, spawning duration and spawning interval) for the 51 species of scombrids globally. We identify major biological gaps in knowledge and prioritize life history research needs in scombrids based on their biological gaps in knowledge, the importance of their fisheries and their current conservation status according to the International Union for Conservation of Nature Red List. We find that the growth and reproductive biology of tunas and mackerel species have been more extensively studied than for Spanish mackerels and bonitos, although there are notable exceptions in all groups. We also reveal that reproductive biology of species, particular fecundity, is the least studied biological aspect in scombrids. We identify two priority groups, including 32 species of scombrids, and several populations of principal market tunas, for which life history research should be prioritized following the species-specific life history gaps identified in this study in the coming decades. By highlighting the important gaps in biological knowledge and providing a priority setting for life history research in scombrid species this study provides guidance for management and conservation and serves as a guide for biologists and resource managers interested in the biology, ecology, and management of scombrid species.     

Past, present and future of fishery management on one of the world’s last remaining pristine great lakes: Great Bear Lake, Northwest Territories, Canada

Great Bear Lake, Northwest Territories, Canada supports important sport and aboriginal-subsistence fisheries and is among the last remaining pristine great lakes of the world. The lake’s unique ecology is characterized by a harsh subarctic climate, low productivity and species diversity, and high intraspecific diversity of lake trout. These aspects in combination with geographical remoteness present special challenges to the management of two exceptionally different fisheries. The history of its management has not been well documented or reviewed; therefore, our objectives in this paper were to summarize the history and status of Great Bear Lake’s fisheries and their management, and to identify gaps in knowledge, future challenges, and actions required to meet those challenges. Prior to 1970, management goals for the lake had not been established formally, and harvest numbers and biological characteristics of fish were unknown. To reduce data gaps, creel surveys, gillnet assessments, fish tagging, and subsistence monitoring were implemented. During the 1980s, Canada established the management goal of conserving a high quality sport fishery, while protecting aboriginal access to the subsistence fishery. On the basis of assessment data, lodge harvest quotas, lodge guest capacity limits, individual angler harvest limits, and angler licensing were among the management actions taken to achieve that goal. Since 2005, decision making has been guided by the “water heart,” a management plan for Great Bear Lake. Management has since evolved into a complex co-management system among aboriginal, territorial, and federal governments. Changes in regulations, sport trophy and tourism industries, subsistence resource use, and social and cultural norms and practices contributed to changes in the Great Bear Lake fishery and its management. In the future, anthropogenic and climate change are the two main challenges facing co-management of the lake’s resources. We recommend the adoption of an ecosystem approach to management, establishment of a fishery technical committee, reformulation of the current plan, explicit commitment to evaluation, conducting community-based monitoring, and development and use of a joint strategic plan among co-managers to describe how to interact and implement the Great Bear Lake management plan.     

Fisheries stock assessment and decision analysis: the Bayesian approach

The Bayesian approach to stock assessment determines the probabilities of alternative hypotheses using information for the stock in question and from inferences for other stocks/species. These probabilities are essential if the consequences of alternative management actions are to be evaluated through a decision analysis. Using the Bayesian approach to stock assessment and decision analysis it becomes possible to admit the full range of uncertainty and use the collective historical experience of fisheries science when estimating the consequences of proposed management actions. Recent advances in computing algorithms and power have allowed methods based on the Bayesian approach to be used even for fairly complex stock assessment models and to be within the reach of most stock assessment scientists. However, to avoid coming to ill-founded conclusions, care must be taken when selecting prior distributions. In particular, selection of priors designed to be noninformative with respect to quantities of interest to management is problematic. The arguments of the paper are illustrated using New Zealand's western stock of hoki, Macruronus novaezelandiae (Merlucciidae) and the Bering--Chukchi--Beaufort Seas stock of bowhead whales as examples     

Review of the life history characteristics,ecology and fisheries for deep-water tropical demersal fish in the Indo-Pacific region

Deep-water tropical fishes support locally significant commercial fisheries, high value recreational fisheries, and culturally and economically important artisanal and subsistence fisheries throughout the Indo-Pacific region. The main species captured by these fisheries are deep-water snappers (Lutjanidae), groupers (Epinephelidae), and emperors (Lethrinidae). Quantitative assessments of deep-water tropical fisheries have been limited by a lack of adequate biological and fisheries data. We review the biology and ecology of deep-water tropical fishes, discuss the implications for assessment and management of tropical deep-water fisheries, and provide perspectives on future research priorities. We found that biological and fisheries information is lacking for the majority of deep-water tropical fishes. Furthermore, many studies were constrained by low samples sizes and the use of methods that have not been validated or verified. Most species for which reliable information was available were reported to have extended longevities (>20 years), low rates of natural mortality (M < 0.15), and slow to modest growth rates (K = 0.12–0.25). These life history traits indicate a low production potential for many deep-water tropical fishes, and suggest that sustainable exploitation rates and potential yields may be low. There is a need for more representative and adequate studies of deep-water tropical fishes and for improved fisheries data collection and the use of consistent methods in addition to information sharing to facilitate the development of robust data-poor assessment techniques for these species.     

Assessment of exploited fish species in the Lake Edward System,East Africa

The unknown status of inland fish stocks hinders their sustainable management. Therefore, increasing stock status information is important for sustainable inland fisheries. Fisheries reference points were estimated for five exploited fish species (11 stocks) in the Lake Edward system, East Africa, which is one of the most productive inland water systems. The aim was to ascertain the status of the fisheries and establish reference points for effective management. The reference points were based on four linked stock assessment approaches for data-limited fisheries. Estimates showed poor stock status with the stocks defined as either collapsed, recruitment impaired or overfished. However, higher catches could be obtained under sustainable management. Estimates of maximum sustainable yield (MSY) and supporting biomass (B_msy) are provided for 10 of the stocks as targets for rebuilding plans. The immediate target of management should be rebuilding biomass to B_msy. Applicable measures include shifting length at first capture to the length that maximizes catch without endangering size structure and biomass, and livelihood diversification out of fisheries.     

Putting all the pieces together: integrating current knowledge of the biology,ecology, fisheries status,stock structure and management of yellowfin tuna (<Emphasis Type="Italic">Thunnus albacares</Emphasis>)

Yellowfin tuna (Thunnus albacares; YFT) is an apex marine predator inhabiting tropical and sub-tropical pelagic waters. It supports the second largest tuna fishery in the world. Here, we review the available literature on YFT to provide a detailed overview of the current knowledge of its biology, ecology, fisheries status, stock structure and management, at global scale. YFT are characterized by several peculiar anatomical and physiological traits that allow them to survive in the oligotrophic waters of the pelagic realm. They are opportunistic feeders, which allows fast growth and high reproductive outputs. Globally, YFT fisheries have expanded over the last century, progressively moving from coastal areas into the majority of sub-tropical and tropical waters. This expansion has led to a rapid increase in global commercial landings, which are predominantly harvested by industrial longline and purse seine fleets. For management purposes, YFT is divided into four stocks, each of which is currently managed by a separate tuna Regional Fisheries Management Organization. Our current understanding of YFT stock structure is, however, still uncertain, with conflicting evidence arising from genetic and tagging studies. There is, moreover, little information about their complex life-history traits or the interactions of YFT populations with spatio-temporally variable oceanographic conditions currently considered in stock assessments. What information is available, is often conflicting at the global scale. Finally, we suggest future research directions to manage this valuable resource with more biological realism and more sustainable procedures.     

Monitoring programs of the U.S. Gulf of Mexico: inventory,development and use of a large monitoring database to map fish and invertebrate spatial distributions

Since the onset of fisheries science, monitoring programs have been implemented to support stock assessments and fisheries management. Here, we take inventory of the monitoring programs of the U.S. Gulf of Mexico (GOM) surveying fish and invertebrates and conduct a gap analysis of these programs. We also compile a large monitoring database encompassing much of the monitoring data collected in the U.S. GOM using random sampling schemes and employ this database to fit statistical models to then map the spatial distributions of 61 fish and invertebrate functional groups, species and life stages of the U.S. GOM. Finally, we provide recommendations for improving current monitoring programs and designing new programs, and guidance for more comprehensive use and sharing of monitoring data, with the ultimate goal of enhancing the inputs provided to stock assessments and ecosystem-based fisheries management (EBFM) projects in the U.S. GOM. Our inventory revealed that 73 fisheries-independent and fisheries-dependent programs have been conducted in the U.S. GOM, most of which (85%) are still active. One distinctive feature of monitoring programs of the U.S. GOM is that they include many fisheries-independent surveys conducted almost year-round, contrasting with most other marine regions. A major sampling recommendation is the development of a coordinated strategy for collecting diet information by existing U.S. GOM monitoring programs for advancing EBFM.     

Stock structure analysis of ‘Bombay duck’ (Harpadon nehereus Hamilton, 1822) along the Indian coast using truss network morphometrics

Harpadon nehereus, commonly known as ‘Bombay duck’, is a fish with a discontinuous distribution along the Indian peninsula. The fisheries are dominant on the north‐east and north‐west coast but are absent in commercial landings below 15° north latitude. Heretofore stock assessment studies had not considered the various spawning stock components that replenish this fishery, therefore the present study. Fish samples were collected from four locations: two each from the northeast and the northwest coasts. Twenty‐four morphometric variables were measured using a box‐truss network method. Factor analysis of these variables differentiated the east and the west coast fish populations. Multiple comparisons on the factor scores indicated two independent stocks on the east coast, whereas the fishery on the west coast is replenished by a single stock. The important morphometric traits that accounted for most of the stock variations were related to swimming adaptations of the fish. Future stock assessments can consider the population on the west coast as a single stock when formulating management plans. To harvest the resource in a sustainable manner, the maritime states on the west coast should adopt collaborative efforts towards managing this fishery.     

The Fishery Performance Indicators: A Management Tool for Triple Bottom Line Outcomes

Pursuit of the triple bottom line of economic, community and ecological sustainability has increased the complexity of fishery management; fisheries assessments require new types of data and analysis to guide science-based policy in addition to traditional biological information and modeling. We introduce the Fishery Performance Indicators (FPIs), a broadly applicable and flexible tool for assessing performance in individual fisheries, and for establishing cross-sectional links between enabling conditions, management strategies and triple bottom line outcomes. Conceptually separating measures of performance, the FPIs use 68 individual outcome metrics—coded on a 1 to 5 scale based on expert assessment to facilitate application to data poor fisheries and sectors—that can be partitioned into sector-based or triple-bottom-line sustainability-based interpretative indicators. Variation among outcomes is explained with 54 similarly structured metrics of inputs, management approaches and enabling conditions. Using 61 initial fishery case studies drawn from industrial and developing countries around the world, we demonstrate the inferential importance of tracking economic and community outcomes, in addition to resource status.