International Pacific Halibut Commission Research Articles

Biological characteristics of the Pacific halibut in the Bering Sea and off the eastern coast of Kamchatka in spring 2022

The purpose of the work: to give a biological characteristic of the Pacific halibut in different areas of the Bering Sea and off the eastern coast of Kamchatka and to analyze its size age composition in catches of trawl fishing. Methods used: the material was collected during the expedition research, a complete biological analysis of the Pacific halibut was carried out, the otoliths were selected to determine the age. The age was determined in accordance with the guidelines developed specifically for the Pacific halibut in the International Commission on Pacific Halibut (International Pacific Halibut Commission, IPHC).Novelty: the elements of novelty are generalized and analyzed data on Pacific halibut. The material collected in the waters of Eastern Kamchatka and the Bering Sea in 2022. Pacific halibut from trawl catches have been studied, its biological characteristics have been considered, the size-age composition and growth rate have been analyzed.Practical significance: the results of these studies can be used in forecasting the stocks of Pacific halibut in this area.Result: data on catches of Pacific halibut in different regions of the North West Pacific Ocean, the size and age composition, a comparative characteristic of males and females by growth rate, the age composition of fish by maturity stages.

Environmental conditions on the Pacific halibut fishing grounds obtained from a decade of coastwide oceanographic monitoring, and the potential application of these data in stock analyses

Context Establishing baseline environmental characteristics of demersal fish habitat is essential to understanding future distribution changes and to identifying shorter-term anomalies that may affect fish density during monitoring efforts. Aims Our aim was to synthesise environmental data to provide near-bottom oceanographic baseline information on the Pacific halibut fishing grounds, to establish geographic groupings that may be used as co-variates in fish-density modelling and to identify temporal trends in the data. Methods Water-column profiler data were collected from 2009 to 2018 along the North American continental shelf, during summer fishery surveys focused on Pacific halibut. Key results In addition to establishing baseline information on the fishing grounds, this analysis illustrated that environmental variables can be grouped geographically into four regions that correspond to the four biological regions established by the International Pacific Halibut Commission. A spatio-temporal modelling approach is presented as an example of how to describe the relationship between environmental data and Pacific halibut distribution. Conclusions This study has highlighted the efficacy of environmental data in analysing fish distribution and density changes. Implications Oceanographic monitoring provides the ability to detect annual anomalies such as seasonal hypoxic zones that may affect fish density and to establish baseline information for future research.

Dispersal and seasonal movements of Pacific halibut (Hippoglossus stenolepis) in the eastern Bering Sea and Aleutian Islands, as inferred from satellite-transmitting archival tags

BackgroundUnderstanding connectivity is critical to the management of exploited fish stocks, but migratory dynamics of Pacific halibut (Hippoglossus stenolepis) in the Bering Sea and Aleutian Islands region are not well-understood. In the current study, 145 Pacific halibut ≥ 82 cm fork length were tagged with Pop-up Archival Transmitting (PAT) tags to evaluate interannual dispersal, seasonal migration, and depth-specific habitat use.ResultsEndpoint locations obtained after 1 year at liberty (n = 79), fishery recoveries after 2–3 years at liberty (n = 5), and at-liberty geopositions based on light data (n = 5313 estimates from 109 fish) indicated geographically distinct movement patterns: Pacific halibut tagged in the Western and Central Aleutian Islands remained within the island groups in which the fish had been tagged; fish in the eastern Bering Sea remained in that ocean basin, moving among International Pacific Halibut Commission (IPHC) regulatory areas and into Russian waters; those tagged south of Unimak Pass in IPHC Regulatory Area 4A displayed the greatest amount of emigration, dispersing eastward both seasonally and interannually to as far south as Washington State. Analysis of daily maximum depth and temperature data from 113 individuals demonstrated group-level variation in summer temperatures experienced by the fish and in the timing, duration, and synchrony of movement to deep-water wintering grounds.ConclusionsDepth-specific habitat use was suggestive of regionally explicit migratory contingents, while interannual dispersal patterns were consistent with the existence of multiple functional spawning units. The results may guide future research to examine cross-basin connectivity in the Northern Bering Sea and provide inputs for numerical modelling of individual movements, larval advection, and recruitment analyses.

Fully subscribed: Evaluating yield trade-offs among fishery sectors utilizing the Pacific halibut resource

The Pacific halibut (Hippoglossus stenolepis) stock in the waters of the exclusive economic zones of Canada and the United States of America has been actively managed by the International Pacific Halibut Commission since its formation in 1923. Fisheries accessing this resource have become increasingly varied over time and among geographical areas, and more than capable of utilizing the entire yield available each year, which has averaged 34,000 mt since 1992. In recent years, 69.5 % of the mortality has come from the directed commercial fishery landings, 15.4 % from non-directed commercial fisheries (legally restricted from retaining any halibut) and 15.1 % from all other sources combined (commercial discards, recreational, subsistence). Understanding the relative effects on the stock and potential yield of allocation among fishery sectors is a high priority for managers and participants in these fisheries. This analysis used the 2019 stock assessment for Pacific halibut and three analytical methods to compare the directed and non-directed commercial fisheries. We found that potential yield to the directed fishery was generally larger than a simple reallocation from non-directed discards (115 % on average), that the rate of exchange is variable over time (range of 86–139 %), and that the effect of the directed commercial fishery on the spawning biomass has also changed over time. We conclude that managers should be aware that no simple ‘conversion rate’ exists for translating mortality among fisheries that differ appreciably when operating on a stock with dynamic biology.

Climate effects and bottom‐up controls on growth and size‐at‐age of Pacific halibut (Hippoglossus stenolepis) in Alaska (USA)

AbstractPacific halibut (Hippoglossus stenolepis) are an ecologically, commercially, and culturally important Alaskan groundfish species. Commercial harvest of halibut dates back to the late 19th century and has been managed by the International Pacific Halibut Commission (IPHC) since 1921. IPHC surveys have revealed declining trends in survey biomass in multiple regions and region‐specific declines in mean size‐at‐age (size‐at‐age) over the past two decades (>50% in some areas). Changes in size‐at‐age can arise from a variety of physical, ecological, sampling, and fishery effects, including size‐dependent fishery or predation mortality, alteration in growth from variability in prey quality or quantity, and changes in temperature‐dependent metabolic demands. Here, we develop and apply a bioenergetics model for halibut using survey‐based diet and temperature data for Alaska to evaluate potential environmental drivers of size‐at‐age. In general, juvenile (<40 cm fork length) foraging rates were highest in the Gulf of Alaska concomitant with higher potential growth and elevated basal metabolic demands during warm summer conditions. In contrast, adult (40–120 cm FL) potential growth was highest in the Eastern Bering Sea, potentially reflecting lower metabolic costs and higher rates of prey consumption in that region. We additionally find evidence for interannual variation in potential growth, with a higher frequency of reduced growth potential in the last decade, particularly in the Eastern Bering Sea in 2015 and 2016 for both juvenile and adult halibut. These results suggest the potential for patterns in size‐at‐age to arise from trophic and environmental constraints that collectively limit growth in some regions and years.

The International Pacific Halibut Commission and Social Media

The International Pacific Halibut Commission and Social Media

Declining size and age of rockfishes (Sebastes spp.) inherent to Indigenous cultures of Pacific Canada

Yelloweye Rockfish (Sebastes ruberrimus) and Quillback Rockfish (S. maliger) are important foods in the traditional diets of Indigenous people in coastal British Columbia (BC), Canada. These species are vulnerable to overexploitation because fecundity increases with maternal size or age, yet large-scale fisheries truncate size and age structures. In BC's Central Coast, Indigenous fishers have observed declines in the size and abundance of rockfishes, particularly since the commercial over-exploitation that occurred in the late 1970s and 1980s. To address this conservation concern, we analyzed fishery-independent data collected annually since 2003 by the International Pacific Halibut Commission (IPHC) and the Pacific Halibut Management Association (PHMA). These surveys are coast-wide, yet we focused on data for BC's Central Coast and vicinity. Linear mixed models tested for temporal trends in size and age while controlling for environmental variables. IPHC and PHMA surveys differed in field methodology and were analyzed separately. For Yelloweye Rockfish, fork length declined at average rates of −3.53 mm yr−1 (IPHC: 2003–2015) or −4.26 mm yr−1 (PHMA: 2006–2015), and age declined at average rates of −0.73 yrs yr−1 (IPHC: 2003–2012) or −0.86 yrs yr−1 (PHMA: 2006–2012). The fork length of Quillback Rockfish declined at an average rate of −4.57 mm yr−1 (PHMA: 2006–2015). Although rockfish management in BC has become more conservative since the early 2000s, the abundances of Yelloweye and Quillback Rockfish remain at historical low levels. Our results, along with the body of work that precedes them, suggest that loss of reproductive potential associated with size and age truncation could be hampering recovery. Current management criteria, however, are biomass-based and might fail to address this problem. Incorporating old age and large size structures into management objectives could enhance rockfish recovery and help maintain the cultural integrity of Indigenous people who rely on these species.

Subtle genetic population structure in Pacific halibut Hippoglossus stenolepis.

Pacific halibut Hippoglossus stenolepis from 10 sampling locations throughout their range were investigated for signs of population structure. Two genetic data sets were created: (1) all individuals (n = 828) at few anonymous microsatellite markers (number of loci = 16); (2) fewer individuals (n = 435) genotyped at anonymous as well as expressed sequence-tag linked microsatellites (number of loci = 61). A combination of multidimensional scaling plots, discriminant analysis of principal components and pairwise differentiation estimates suggested that samples from the Aleutian Islands, particularly the western Aleutian Islands, were genetically distinct from samples collected in other regions. In addition, outlier analyses found that two markers linked to expressed sequence tags may be under directional selection and could explain the differentiation among samples. These results confirm findings from previous research and suggest that population structure may exist within a current management unit (i.e. International Pacific Halibut Commission Regulatory Area 4B).

Mercury concentrations in Alaska Pacific halibut muscle relative to stable isotopes of C and N and other biological variables

Total mercury concentrations ([THg]), δ15N and δ13C values were determined in muscle of 693 Pacific halibut caught in International Pacific Halibut Commission setline surveys in Alaska (2002−2011). Project goals were to evaluate whether 1) δ15N and δ13C varied with region, age, sex and length of halibut, and 2) muscle [THg] varied with δ15N and δ13C (feeding ecology) while accounting for sex, length, and region. Variation in [THg] was explained, in part, by halibut feeding ecology as [THg] increased with trophic position (increasing δ15N). Halibut from the western Aleutian Island region were the exception, with overall lower δ15N values and significantly higher [THg] than halibut from other Alaskan waters. This [THg] pattern has been observed in other Aleutian biota, possibly the result of northeasterly atmospheric movement of mercury emissions from Asia and/or other local sources and processes. The significantly lower δ15N values for these halibut warrants further investigation of halibut prey.

Pacific halibut on the move: a renewed understanding of adult migration from a coastwide tagging study

Results of a coastwide tagging study show that ontogenetic migration of Pacific halibut (Hippoglossus stenolepis) continues for larger fish, whereas in recent years the assumption had been that only smaller, younger fish migrated. In 2003–2004, a total of 67 000 Pacific halibut tagged with passive integrated transponder tags were released by the International Pacific Halibut Commission (IPHC) from Oregon to the Bering Sea. Portside scanning recovered over 3000 of these tags. Models were fitted that allowed commercial fishing mortality to be a function of fish length, year, and IPHC regulatory area, while migration probability was a function of area and length. Estimates from the models support the view that exploitation rates were much higher in eastern than western areas prior to the reduction of quotas following new results from a coastwide stock assessment in 2007. We explore possible explanations for differences between tagging and IPHC stock assessment results and note that this research provides confirmation of historical inferences regarding patterns of halibut migration based on conventional tagging.

Evaluation of Video Technology for Monitoring of Multispecies Longline Catches

AbstractAt‐sea catch monitoring of the Alaskan longline fishery for Pacific halibut Hippoglossus stenolepis is insufficient. The International Pacific Halibut Commission (IPHC) conducted studies in 2002 and 2004 comparing catch composition data from electronic monitoring (EM) systems to those of at‐sea observers. The EM systems use automated data loggers linked to digital video cameras, a transducer on shipboard hydraulic systems, and a global positioning system receiver. The goal of both studies was to determine whether EM technologies could provide precise and verifiable catch composition data on commercial longline vessels to supplement and complement the data collected by fisheries observers. The EM video analyst's catch data were similar to the observers' data in the 2002 study; however, the video analyst recorded fewer fish for 7 of the 17 species categories investigated. In 2004, the IPHC employed EM technology in another study incorporating recommendations from the 2002 study, including improved camera configurations. The video analyst's data showed increased agreement with the observer data. However, the observers recorded slightly fewer individuals of some species categories, opposite the findings of the 2002 study. This change suggests that incorporating the technology recommendations enhanced the video analyst's accuracy relative to the observer data. Our analysis also highlights the fact that data provided by human observers have their own suite of errors and that the comparisons between EM and observers have no absolute standard of reference. The findings indicate that EM technology can effectively address the lack of catch composition data in the Pacific halibut and other hook‐and‐line fisheries in Alaska.

A General Model for Analyzing Data from Mark-recapture Experiments with an Application to the Pacific Halibut

A general model is developed to examine the patterns of the regional movement of tagged and released fish from mark-recapture experiments. It is a stochastic model that incorporates fishing mortality, natural mortality, fish movement, tag-shedding, and different rates of reporting. A likelihood function is constructed for estimating its parameters. We used this model to analyze data on the Pacific halibut from mark-recapture experiments conducted by the International Pacific Halibut Commission (IPHC), with a total of 36,058 releases from 1982 to 1986 and 5,826 recoveries from 1982 to 2000. We estimated their rates of movement among IPHC management areas, along with their instantaneous rates of natural and fishing mortalities. Our analysis revealed that fish movement was not significant among areas, with a resident probability of > 0.92. This lends support to the IPHC catch-at-age stock assessment model (which has no built-in movement components). The estimated instantaneous rate of natural mortality (0.198 year−1) lies between that assumed in all IPHC stock assessments before 1998 (0.20 year−1) and that from 1999 onwards (0.15 year−1). The estimates of the instantaneous rates of fishing mortality were consistent with those from the IPHC stock assessment model.

A Conditional Constant Catch Policy for Managing the Pacific Halibut Fishery

Abstract Since 1985, the staff of the International Pacific Halibut Commission (IPHC) has used a constant harvest rate policy—currently 20% of exploitable biomass—to estimate the yield currently available from Pacific halibut Hippoglossus stenolepis stock. This paper outlines a more stable alternative policy in which yield is held constant at some ceiling level so long as taking that yield would not result in a total exploitation rate exceeding a specified ceiling rate. During any periods of low abundance, the policy would revert to a constant harvest rate policy at the ceiling rate. The ceiling harvest rate would be chosen so as to assure that spawning biomass remained above a specified minimum. A policy of this kind could produce a yield similar to the present 20% constant harvest rate policy but with much less year-to-year variation attributable to changes in stock abundance, assessment methods, and estimated removals by other fisheries.

A MODEL FOR THE WORLD: 80 YEARS OF MODEL DEVELOPMENT AND APPLICATION AT THE INTERNATIONAL PACIFIC HALIBUT COMMISSION

ABSTRACT. This is a short history of modeling work done by the staff of the International Pacific Halibut Commission, from the pioneering work of Thompson and Bell through the present.

Jurisdictional and administrative limitations affecting management of the halibut fishery

Abstract The Canadian‐U.S. Halibut Convention and its Enabling Acts were re‐examined to assess the ability of the International Pacific Halibut Commission (IPHC) to manage the fishery under the existing terms of reference and to re‐evaluate the need for international management of the halibut resource. National goals such as limited entry and optimum yield have not been incorporated in the terms of the existing Convention and these inconsistencies, as well as administrative deficiencies concerning enforcement and staffing, have limited the effectiveness of IPHC. A revision of the present treaty and associated legislation is recommended and suggestions are made for the restructuring of international arrangements now under study by the federal governments.

Management of the Pacific Halibut Fishery

The International Pacific Halibut Commission (IPHC) has managed the Canadian and United States halibut fishery since 1923. During the early years of the Commission the abundance of the halibut stocks was declining and there were major changes in fishing techniques. After 1930 the Commission instituted more regulatory control, and catches gradually improved, reaching a maximum in the early 1960s. Some scientists attribute IPHC’s success to its organizational structure; others credit the simplicity of the fishery; still others contend that success was possible because the two nations have similar cultures. A more important factor has been the control of the fishery, i.e. the authority to introduce conservation measures that are supported by adequate enforcement.Since 1960 IPHC has lost control of certain elements in the fishery, and the abundance of halibut has declined markedly. The total catch by the North American longline fleet in 1962 was approximately 45,000 metric tons, while in 1972 it was 25,000 metric tons (round weight). Maximum catch per unit effort (CPUE) was reached before the expansion of domestic (Canada and United States) and foreign trawling. In the late 1950s IPHC had increased the removals to test the estimated maximum sustained yield (MSY) of the stock and expected a decline in CPUE when fishing intensity was increased; however, the rate of decrease was greater and lasted longer than anticipated. Changes in recruitment may have contributed to this decline. By 1965, the incidental catch of halibut by foreign and domestic trawl fisheries had increased substantially, and this accelerated the decrease in abundance. Reductions of the catch limits of the longline fleet failed to arrest the decline. In addition, longline fishermen had improved the effectiveness of their gear by increasing the spacing between hooks; as a result IPHC’s measure of CPUE since 1960 was overestimated. The effects of this gear change are far reaching and basic parameters of the halibut populations must be reassessed. Though the fishery has changed measurably, and IPHC has lost some control through the incidental catch by trawlers, a viable fishery has been maintained through the sacrifice of yield by the North American longline fleet. Productivity of this fishery is in jeopardy because losses to trawl fleets are not controlled, and continue to increase.

A Study of Production and Factor Shares in the Halibut Fishing Industry

A LARGE number of empirical studies in the area of production functions in recent years have used aggregative time-series data. As a result, the inferences drawn from such studies with respect to the functional forms and the nature of technical progress have not been duly convincing because of the aggregation and related problems. In the present study, we utilize a panel of thirty-two halibut fishing boats representing data that cover seven years of the boats' fishing operations. Halibut fishing in the North Pacific is regulated by the International Pacific Halibut Commission, and the regulations are provided for by a convention between the United States and Canada. The regulatory measures, which are based on biological studies, aim at providing a maximum sustainable yield of

International North Pacific Fisheries Commission

The Convention for the High Seas Fisheries of the North Pacific Ocean was signed at Tokyo on May 9, 1952, on behalf of Canada, Japan, and the United States, and came into effect on June 12, 1953, upon the exchange of ratifications by the three governments at Tokyo. The first meeting of the Commission was held in Washington, D.C., in February 1954. Canada, the United States, and Japan sent representatives, and invitations to send observers were extended to FAO, the International Pacific Halibut Commission, the International Salmon Fisheries Commission, the International Commission for the Northwest Atlantic Fisheries, and the Inter-American Tropical Tuna Commission. The purposes of the conference were “to decide matters of organization, to prepare coordinated programs of research on the stocks of fish that are of common concern to the three countries, and, generally, to carry out the commitments of the convention”. The Commission decided to establish temporary headquarters at the University of British Columbia in Vancouver, B.C.