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Pacific halibut (Hippoglossus stenolepis) supports one of the most valuable groundfish fisheries in the North Pacific Ocean and the north American component has been managed by the International Pacific Halibut Commission since 1923. From its establishment, IPHC’s work has been focused on data collection and research programs to better understand stock dynamics, extent, and behavior across its range. In this review we summarize the 100 years of migration research available for Pacific halibut, with a focus on tagging experiments. A visual representation of all tags deployed and recovered is included, and all of the information available from different research (e.g. genetic analyses, oceanographic models, catch trends, IBM) has been unified into a conceptual model of Pacific halibut movement from southern California through the Bering Sea. From spawning grounds in the Gulf of Alaska, eggs and larvae are transported westward, some crossing Aleutian Island passes into the Bering Sea. Once settled, there is compensatory migration as some juveniles move back into the Gulf of Alaska. In the Gulf of Alaska, juveniles and adults exhibit net migration eastward and southward along the continental shelf of the US and Canadian coasts. Adults undertake seasonal migrations from feeding grounds to spawning grounds. While little information is available for the western side of the Pacific halibut range, research suggests a constant exchange across the Bering Sea between the eastern and western grounds. The hypothesis of multiple migratory behaviors is suggested. This review will serve as a guide for current modeling efforts and future research planning.

Accurate characterization of oocyte development is essential to understanding foundational aspects of reproductive biology and successful management of Pacific halibut (Hippoglossus stenolepis). Here this study provides complete histological descriptions for eight oocyte developmental stages in addition to postovulatory follicles and demonstrates the potential for oocyte size frequency distribution to act as a proxy for ovarian developmental stage and future maturity assessments. Importantly, it provides the first histological evidence that Pacific halibut have a group‐synchronous ovarian developmental pattern with determinate fecundity and support for their batch‐spawning strategy.

The British Columbia longline fishery for Pacific halibut (Hippoglossus stenolepis) has experienced important recent management changes, including the introduction of comprehensive electronic catch monitoring on all vessels; an integrated transferable quota system; a reduction in Pacific halibut quotas; and, beginning in 2016, sharp decreases in quota for yelloweye rockfish (Sebastes ruberrimus, an incidentally caught species). We describe this fishery before integration, after integration, and after the yelloweye rockfish quota reduction using spatial clustering methods to define discrete fishing opportunities. We calculate the relative utilization of these fishing opportunities and their overlap with areas with high encounter rates of yelloweye rockfish during each of the three periods. The spatial footprint (area fished) increased before integration, then decreased after integration. Each period showed shifts in utilization among four large fishing areas. Immediately after the reductions in yelloweye rockfish quota, fishing opportunities with high encounter rates of yelloweye rockfish had significantly lower utilization than areas with low encounter rates, implying rapid avoidance behaviour.

The width of trophic niches of the Kamchatka flounder Atheresthes evermanni, the Pacific halibut Hippoglossus stenolepis, and the Greenland halibut Reinhardtius matsuurae have been assessed quantitatively on the Western Kamchatka shelf of the Sea of ​​Okhotsk using the data of isotopic signatures of carbon (δ13C) and nitrogen (δ15N) of their prey. According to the corrected standard ellipse area, the trophic niche widths of the Kamchatka flounder, Pacific halibut, and Greenland halibut are 11.35, 9.41, and 12.36, respectively. The range of δ15N isotopic signatures (8.80–17.61) corresponds to the trophic level 2.63–5.22. According to the limits of variation of δ13C (–14.99… –22.9), the basic carbon sources for halibuts are the prey groups belonging to plankton, nekton, and nectobenthos. The maximum value of the niche overlap belongs to the Kamchatka flounder (93.25%) in the niche of the Greenland halibut; the minimum, on the contrary, belongs to the Greenland halibut (73.19%) in the niche of the Kamchatka flounder. The high degree in similarity of system-wide niche indicators calculated from the isotopic signatures of halibut/flounder prey is balanced by the differences of other parameters in specific habitats: depth, temperature, and food spectra variability in ontogenesis.

Hippoglossus stenolepis Schmidt, 1904. Pacific Halibut. To 2.67 m (8.78 ft) TL (Clemens and Wilby 1961). Northern Sea of Japan, Sea of Okhotsk to Kuril Islands, Commander and Aleutian Islands through Bering Sea (Mecklenburg et al. 2016), to northeastern Chukchi Sea (71��12���N, 163��05���W) (Mecklenburg et al, 2010), to Punta Camalu, Baja California (Allen and Smith 1988). Benthic; depth: 2���2,000 m (8���6,560 ft) (min.: Thomas Hurst, pers. comm. to M.L. from sampling reported in Hurst 2016; max.: Pietsch and Orr 2019)., Published as part of Love, Milton S., Bizzarro, Joseph J., Cornthwaite, Maria, Frable, Benjamin W. & Maslenikov, Katherine P., 2021, Checklist of marine and estuarine fishes from the Alaska-Yukon Border, Beaufort Sea, to Cabo San Lucas, Mexico, pp. 1-285 in Zootaxa 5053 (1) on page 219, DOI: 10.11646/zootaxa.5053.1.1, http://zenodo.org/record/5578008, {"references":["Clemens, W. A. & Wilby, G. V. (1961) Fishes of the Pacific Coast of Canada, Second Edition. Bulletin of the Fisheries Research Board of Canada, 68.","Mecklenburg, C. W., Mecklenburg, T. A., Sheiko, B. A. & Steinke, D. (2016) Pacific Arctic Marine Fishes. Conservation of Arctic Flora and Fauna, Akureyri.","Allen, M. J. & Smith, G. B. (1988) Atlas and zoogeography of common fishes in the Bering Sea and northeastern Pacific. NOAA Technical Report NMFS, 66.","Hurst, T. P. (2016) Shallow-water habitat use by Bering Sea flatfishes along the central Alaska Peninsula. Journal of Sea Research, 111, 37 - 46. https: // doi. org / 10.1016 / j. seares. 2015.11.009","Pietsch, T. W. & Orr, J. W. (2019) Fishes of the Salish Sea. University of Washington Press, Seattle."]}

Comparative bioinformation analysis of nucleotide composition of subunit 1 cytochrome oxydase gene (Co-1) mtDNA subunit of north-okhotomore population with representatives of other halibut genera was carried out. Statistical analysis of nucleotide sequences of a fragment of the gene cytochrome oxidase mtDNA of pacific halibut Hippoglossus stenolepis: haplotype diversity 0.852 ± 0.0059, nucleotide 0.00430 ± 0.009465. About 1% of the total value of nucleotide diversity in individuals from eastern and western regions is determined. Analysis of nucleotide sequences of the same gene in pacific greenland halibut Reinhardtius hippoglossoides matsuurae: haplotype diversity was 0.806 ± 0.0399, nucleotide diversity - 0.00185 ± 0.000149. About 6% of the relative value of nucleotide diversity is determined by interpopulation differences. The minimum value of haplotype diversity was determined in the northern halibut flounder Hippoglossus robustus, while in the second species of this genus Hipploglossus platessoides, the haplotype diversity is similar to the representatives of two genera Cleisthenes and Hippoglossus. The maximum value of haplotypic diversity was found in the Cleisthenes herzensteini, representatives of the Atherestes and Reinchardtius genera have intermediate values. The species Atherestes stomias is sharply separated from species of other genera, which is associated with a high degree of genetic differences between representatives of this genus and those from other genera.

Bycatch of Pacific halibut (Hippoglossus stenolepis) limits many trawl fisheries in Alaska and greatly concerns stakeholders from local communities and fisheries that rely on Pacific halibut. To reduce Pacific halibut mortality, trawlers in the Bering Sea that target flatfish have been developing expedited release procedures to sort Pacific halibut from catches earlier than current regulations allow, while continuing accurate bycatch accounting. We studied survival rates of released Pacific halibut from three trawlers by deploying accelerometer-equipped pop-up satellite archival tags (PSATs) on 160 fish handled under expedited procedures. PSATs recorded and transmitted two metrics indicating swimming activity every 2 h while attached to the fish (for up to 60 days). Analysis of the resulting survival outcomes largely validated current survival-estimation methods, based on structured viability assessments, and found that longer fish length, shorter duration of air exposure, and shorter duration of trawl tow improved predicted Pacific halibut survival. Differences in these results were detected among vessel trips and species targeted by trawling. PSATs provided detailed data from nearly all tagged fish, while exposing fish to conditions experienced by normal releases.

The ecological mechanisms driving an observed decline in the mean size-at-age of adult Pacific halibut (Hippoglossus stenolepis) in the eastern North Pacific Ocean have yet to be defined. Here, we present the results of a study designed to investigate the relationship between one potential mechanism — diet — and size-at-age using carbon and nitrogen stable isotope analysis. Our results indicate significant differences in the skeletal muscle δ13C and δ15N values between size-at-age categories for each sex, with larger-size-at-age fish consuming diets with higher δ15N values, indicating higher trophic level feeding. Analysis of Bayesian standard ellipse areas showed that for females, intermediate size-at-age categories have the largest dietary range. For males, the largest dietary range was observed in the largest size-at-age category. Our results suggest a size-based stratification in dietary strategy for Pacific halibut with implications for observed declines in size-at-age.

The integration of multiple tissues in physiological and ecological analyses can enhance methodological approaches, increase applications for data and extend interpretation of results. Previous investigations of the stress response in fish have focused primarily on cortisol levels in a single matrix—blood plasma—which confines interpretations of cortisol levels to a short temporal frame. Epidermal mucus has been proposed as an alternative or complement to plasma that may provide a view to cortisol levels over a different temporal window allowing comparative assessment. Here, we explore the potential for multi-tissue cortisol analysis using both plasma and epidermal mucus in Pacific halibut (Hippoglossus stenolepis). The relative timing at which cortisol increased and decreased in the two matrices as well as cortisol concentrations at estimated peak levels were compared in two trials after (i) inducing cortisol synthesis by adrenocorticotropic hormone (ACTH1–24) administration and (ii) inducing cortisol elimination using cortisol (hydrocortisone, 98%) injection. The ACTH treatment elicited a peak plasma cortisol response approximately 12 hours post-injection, while mucus cortisol concentrations peaked later at approximately 62 hours post-injection. Exogenous cortisol treatments suggested relatively little transfer of cortisol from plasma to mucus, potentially reflecting differential effects of endogenous and exogenous cortisol. Our results suggest the potential utility of mucus as a sampling matrix that provides an extended window for detection of the stress response as compared to plasma. Results also suggest the utility of a multi-tissue approach to cortisol analysis with potential applications to applied fisheries research. Increased understanding of the relative scale of the cortisol response to stress (e.g. capture) will allow researchers and managers to better interpret the physiological condition and survival outcome of fish subjected to regulatory discard.

In the U.S. West Coast groundfish bottom trawl fishery, Pacific halibut (Hippoglossus stenolepis) bycatch can impact some fishers’ ability to fully utilize their quota shares of groundfishes. In this study, we compared the catch efficiency for Pacific halibut and four commercially important groundfish species between an illuminated and non-illuminated trawl. The illuminated trawl caught significantly fewer Pacific halibut and sablefish than the non-illuminated trawl. For Dover sole (Microstomus pacificus), petrale sole (Eopsetta jordani), and lingcod (Ophiodon elongatus), the illuminated trawl caught fewer individuals than the non-illuminated trawl. However, this catch difference was not statistically significant. Physiological data collected on Pacific halibut caught in illuminated and non-illuminated trawls show blood levels of cortisol, a stress hormone, were significantly higher in fish caught in the illuminated trawl than in the non-illuminated trawl in the absence of differences in condition factor or fat content. While our results have obvious implications for the West Coast groundfish bottom trawl fishery, our findings could also have potential applications in Alaska and British Columbia, Canada trawl fisheries where Pacific halibut bycatch occurs.

Changes in the genetic mechanisms that control sexual determination have occurred independently across the tree of life, and with exceptional frequency in teleost fishes. To investigate the genomic changes underlying the evolution of sexual determination, we sequenced a chromosome-level genome, multi-tissue transcriptomes, and reduced representation population data for the Atlantic halibut (Hippoglossus hippoglossus), which has an XY/XX sex determination mechanism and has recently diverged (0.9-3.8 MYA) from the Pacific halibut (Hippoglossus stenolepis), which has a ZZ/ZW system. We used frequency and coverage-based population approaches to identify a putative sex-determining factor, GSDF. We characterized regions with elevated heterozygosity and linkage disequilibrium indicating suppression of recombination across a nascent sex chromosome. We detected testis-specific expression of GSDF, the sequence of which is highly conserved across flatfishes. Based on evidence from genome-wide association, coverage, linkage disequilibrium, testis and brain transcriptomes, and sequence conservation with other flatfishes, we propose a mechanism for the recent evolution of an XY sex-determination mechanism in Atlantic halibut. Changes to the ancestral sex-determining gene DMRT1 in regulating the downstream gene GSDF likely coincided with GSDF, or a proximal regulatory element of it, becoming the primary sex-determining factor. Our results suggest changes to a small number of elements can have drastic repercussions for the genomic substrate available to sex-specific evolutionary forces, providing insight into how certain elements repeatedly evolve to control sex across taxa. Our chromosome-level assembly, multi-tissue transcriptomes, and population genomic data provide a valuable resource and understanding of the evolution of sexual systems in fishes.

Fisheries for Pacific halibut (Hippoglossus stenolepis) in the US Pacific Northwest support a variety of harvest sectors including some that are restricted to coastal offshore waters and others confined to the inland waters of the Salish Sea. Such restrictions have generated interest in the degree to which the Salish Sea represents an extension of the offshore population versus its potential to support an isolated stock. Here, twelve female Pacific halibut were tagged during boreal summer with pop-up archival transmitting (PAT) tags that were programmed to report during either the subsequent winter spawning period or late-spring feeding period. High-resolution depth data failed to produce evidence of spawning within the Salish Sea, while depth-temperature profiles were consistent with the departure of migrants between October and January. Final positions and at-liberty longitude estimates suggest that ~60% of the tagged fish departed the Salish Sea, with confirmed migrations to Canada and Alaska. The recapture in the southern Salish Sea of one fish whose tag had reported earlier from offshore Canadian waters demonstrated the occurrence of cyclic migrations. Evaluation of likely maturity status suggests that local demographics reflect either the cumulative effects of spawning migrations in which some emigrants remain offshore after departing the system, or some combination of enhanced growth or delayed maturity. These findings confirm that the Salish Sea does not represent a functionally-independent stock, but suggest that inshore waters may play a unique role by receiving recruits, rearing individuals to maturity, and exporting spawners to the offshore stock components, while retaining a proportion of site-faithful individuals with cyclic seasonal connectivity with offshore spawning groups.

Examining the reasons why individuals choose to participate or comply with certain fishing regulations is a key part of successful fisheries management. This paper presents a case study that evaluates fisher perceptions of multiple recreational fishery regulations, including traditionally used methods of bag and size limits and a novel regulation involving quota leasing, in the for-hire (i.e., charter) recreational fishing sector for Pacific halibut (Hippoglossus stenolepis) in Alaska. This study examined responses from open-ended and Likert-scale questions from semi-structured interviews with 45 charter operators in Homer and Sitka. Our results highlight that controls on individual harvest can be perceived to have unintended consequences for charter businesses, such as effects on profitability and distance traveled. In response to open-ended questions on a voluntary quota leasing program, participants discussed themes of inequity reflecting broader perceptions of conflicts with the commercial sector and the management system. Perceived inequities that have not been fully addressed can shape how stakeholders feel about current management institutions and affect compliance. Therefore, it is important to understand the historical and political contexts of fishery systems to better anticipate support for future management approaches.

Catch per unit effort (CPUE) is a widely used index of population abundance for informing stock assessments for the purpose of estimating population status and setting fishing policies. However, for CPUE to be an unbiased index, influences that are not related to population abundance (e.g., spatial variation in effort and temporal changes in gear efficiency) must be accounted for in analyses known as CPUE standardization. In longline fisheries, one important factor that can affect CPUE is the spacing between hooks (‘spacing effect’), which influences effective effort and has largely been ignored in previous analyses. Here, we use the Pacific halibut (Hippoglossus stenolepis) long-line fishery as a case study to explore the spacing effect. Both commercial and experimental (fishery-independent) data with hook spacing, and a survey-based CPUE series, are available for this fishery. It thus provides a unique opportunity to explore the effect of hook spacing and its effect on CPUE trends. We quantify this effect using non-parametric and parametric relationships inside a spatially-explicit (geospatial) CPUE standardization model for commercial data, and non-linear mixed-effects model for experimental data. We found a clear non-linear spacing effect (i.e., hooks were less effective the closer they were), but accounting for space had a larger effect on CPUE trends than accounting for hook spacing. For this stock, it is likely the effect of hook spacing on CPUE was minimal due to little variation in average hook spacing over time. Regardless, historical and future trends in hook spacing can have important effects on longline CPUE standardization, highlighting the value of collecting this information. Accounting for hook spacing effects in other fisheries may improve estimates of trends in relative abundance and lead to better management.

Identifying the nursery origins of individual Pacific halibut (Hippoglossus stenolepis) is critical to a refined understanding of regional productivity, the effects of environmental forcing on population dynamics, and the spatial impacts of mortality and bycatch. Otolith microchemistry may provide a tool for identifying fish origins, but a precursor to using microchemistry-based assignment models is to evaluate the extent to which there exists detectable spatial structure in these natural tags. Here, we examined assignment accuracy as a function of spatial scale using canonical discriminant function analyses (DFA) applied to microchemical data from age-2 Pacific halibut in the western Gulf of Alaska (GOA) and southeastern Bering Sea (SEBS). Element:calcium ratios were assayed for fourteen trace elements using inductively coupled plasma mass spectrometry; δ13C and δ18O were determined via isotope ratio mass spectrometry. Substantial assignment success (∼75–90 %) was observed at spatial scales that are consistent with stock management. Elemental signatures were defined primarily by δ18O, δ13C, and 88Sr:48Ca, with a minor contribution from 55Mn:48Ca. Individuals were most commonly mis-assigned to adjacent locations. However, discontinuities were observed within the western GOA that suggest that elemental signatures do not vary along strictly longitudinal and latitudinal clines. These results highlight the need to exercise caution when attempting to use otolith microchemistry to assign fish to their origins when the baseline elemental data are unable to resolve missing nursery sources from the locations that are included in the discrimination models.

Understanding and identifying the genetic mechanisms responsible for sex-determination are important for species management, particularly in exploited fishes where sex biased harvest could have implications on population dynamics and long-term persistence. The Pacific halibut (Hippoglossus stenolepis) supports important fisheries in the North Pacific Ocean. The proportion of each sex in the annual harvest is currently estimated using growth curves, but genetic techniques may provide a more accurate method. We used restriction-site associated DNA (RAD) sequencing to identify RAD-tags that were linked to genetic sex, based on differentiation (FST) between the sexes. Identified RAD-tags were aligned to the Atlantic halibut (Hippoglossus hippoglossus) linkage map, the turbot (Scophthalmus maximus) genome, and the half-smooth tongue sole (Cynoglossus semilaevis) genome to identify genomic regions that may be involved in sex determination. In total, 56 RAD-tags (70 single nucleotide polymorphisms) were linked to sex, and 3 RAD-tags were identified in only females. Sex-linked loci aligned to 3 linkage groups in the Atlantic halibut (LG07: 7 loci, LG15: 1 locus, and LG24: 1 locus), 3 chromosomes in the turbot (LG12: 13 loci, LG01: 1 locus, and LG05: 1 locus), and 1 chromosome in the half-smooth tongue sole (ChrZ: 9 loci). Results add support to the hypothesis that Pacific halibut genetic sex is determined in a ZW system. Two sex-linked loci were further developed into sex identification assays, and their efficacy was tested on individuals that had been morphologically sexed. The accuracy of each assay on its own was 97.5% compared to morphological sex.

As part of its annual bottom-trawl survey program, the Alaska Fisheries Science Center (AFSC) has been collecting and analyzing the stomach contents of groundfish predators since 1981. Between 1981 and 2011, a total of 233,451 fish stomachs were collected and analyzed from the eastern Bering Sea, the Gulf of Alaska, and the Aleutian Islands large marine ecosystems; these data are now available online as AFSC’s Groundfish Trophic Interactions Database. Here, we discuss features of the survey and data to aid in the interpretation and use of this extensive dataset for the Alaska region. The primary fish sampled include walleye pollock (Gadus chalcogrammus), Pacific cod (Gadus macrocephalus), Pacific halibut (Hippoglossus stenolepis), and arrowtooth flounder (Atheresthes stomias), although 159 predator species have been included in the stomach content analysis. Prey length measurements are included for important commercial prey and can identify age or size classes of prey prior to their recruitment into fisheries and most other surveys. With these data, one can track time trends in growth, mortality, and prey composition as ecosystem indicators, and include food web interactions in fish stock assessments for ecosystem-based fisheries management.

Pacific halibut Hippoglossus stenolepis is registered in the Anadyr estuary (Bering Sea basin) for the first time: 20 specimens, 18.5–160.5 cm in length, were caught by trawl and longline within the sea portion of the Anadyr River estuary in August 2010 and September 2015 in highly desalted (23.5‰ on average) and heated (6.5°С) water at a depth of 14–30 meters. Halibut is suggested to form feeding groups within the Anadyr Estuary. An opportunity for organized fishing in this region is discussed.

Hippoglossus stenolepis Schmidt 1904 Sci. Res. Korea–Sakhalin Exp. 1900–1901: 224 Current status: Hippoglossus stenolepis Schmidt, 1904 Type: ZIN 12588 Sakhalin Island, Aniva Bay, Fort Korsakovsky [Korsakov], 27.05.1901, collector P.Yu.Schmidt. Lost between 2000–2010., Published as part of Voronina, Elena P. & Volkova, Galina A., 2019, Annotated catalogue of type specimens of flatfishes (Osteichthyes: Pleuronectiformes) in the Zoological Institute, St. Petersburg, Russia, pp. 253-282 in Zootaxa 4695 (3) on page 279, DOI: 10.11646/zootaxa.4695.3.2, http://zenodo.org/record/3532561, {"references":["Schmidt, P. Yu. (1904) Fishes of the eastern seas of the Russian Empire. Scientific results of the Korea-Sakhalin Expedition of the Emperor Russian Geographical Society 1900 - 1901. Fishes of the eastern seas of the Russian Empire, St. Petersburg, 466 pp. [in Russian]"]}

In the U.S. West Coast limited-entry (LE) groundfish bottom trawl fishery, catches of stocks with restrictive harvest limits (e.g., Darkblotched Rockfish Sebastes crameri, Sablefish Anoplopoma fimbria, and Pacific Halibut Hippoglossus stenolepis) continue to hinder many fishermen’s ability to fully utilize their quota shares of more abundant flatfish stocks (e.g., Dover Sole Microstomus pacificus and Petrale Sole Eopsetta jordani). We used a recapture net to examine the size-selection characteristics of two selective flatfish sorting-grid bycatch reduction devices (BRDs), which were designed to reduce catches of Pacific Halibut and non-flatfish species while retaining target flatfishes. The two devices were identical in materials and design except that the sorting-grid dimensions differed (BRD-1: 6.4- × 25.4-cm grid size; BRD-2: 6.4- × 30.5-cm grid size). The size selectivity for rockfishes, other roundfishes, Pacific Halibut, English Sole Parophrys vetulus, and Rex Sole Glyptocephalus zachirus di...

We examined the structure of the tegument surface of the acanthocephalan Corynosoma strumosum and its surrounding capsule in paratenic hosts: the notched-fin eelpout Zoarces elongatus (Kner, 1868) and the Pacific halibut Hippoglossus stenolepis (Schmidt, 1904). In both cases, the capsules are “leucocytic” and have, in general, a similar structure but with a few peculiarities. Some of them are evidently caused by the different ages of capsules and others may be connected with the species of the host. The tegument surface of C. strumosum from eelpout is covered with a thick layer of glycocalyx, which is absent in acanthocephalans from halibut. The results suggest that the acanthocephalan C. strumosum is more adapted to the eelpout Z. elongatus and to the sculpin Myoxocephalus stelleri than to flatfish.

The U.S. West Coast limited entry groundfish trawl fishery is managed under an individual fishing quota program. For many fishermen targeting flatfishes in this fishery, catches of rockfishes ( Sebastes spp.), sablefish ( Anoplopoma fimbria ), and Pacific halibut ( Hippoglossus stenolepis ) can be a concern because quota is limited relative to flatfish quotas. Thus, approaches to minimize bycatch of limiting species are important to the economic viability of the fishery. In this study, we examined the size-selection characteristics of a flexible sorting grid bycatch reduction device (designed to retain flatfishes while reducing catches of rockfishes, sablefish, and Pacific halibut) using a recapture net. The mean codend retention of target flatfishes (five species evaluated) ranged from 68.1% to 92.3%. Combined, the mean flatfish retention was 85.6%. Codend catches of shelf rockfishes, slope rockfishes, sablefish, and Pacific halibut were reduced by 80.3%, 64.0%, 97.0%, and 90.3% by weight, respectively. Significant differences in selectivity parameters between flatfishes, rockfishes, sablefish, and Pacific halibut were observed. Over fishing grounds where fishermen need a more selective trawl to harvest flatfishes, the experimental gear tested could provide fishermen a technique to reduce catches of non-target species.

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).

There is a growing body of literature evidencing the distributional impacts of leasing in catch-share fisheries but little research on the determinants of the leasing decision itself. This study addresses this gap by using a discrete-choice model to examine the determinants of the decision of quota shareholders to use hired skippers in the individual fishing quota (IFQ) fishery for Pacific Halibut Hippoglossus stenolepis in Alaska. Since the implementation of that Alaska IFQ program, there has been an increasing reliance on hired skippers by initial quota-share recipients in relationships that are often functionally equivalent to leasing. This has hampered the North Pacific Fishery Management Council’s efforts to ultimately transition the IFQ catcher-vessel fleet to a group of owner-operators. This study shows that the probability of hiring a skipper is statistically significantly related to the residency and shareholdings of shareholders and identifies potential attributes of shareholdings, inclu...

Alaska is the world’s principal supplier of Sablefish Anoplopoma fimbria, a buttery-flavored whitefish greatly prized in Japan. Sablefish are distributed from Baja California to western Japan, but the majority of commercial catches are from the Gulf of Alaska and the Aleutian Islands off Alaska. The volume and value of landings of this long-lived demersal fish are comparable to those of the well-known Pacific Halibut Hippoglossus stenolepis. As with Pacific Halibut, Alaska region catches of Sablefish are managed under an individual fishing quota (IFQ) program implemented in 1995. We present a simultaneous-equation market model for Sablefish and use it to examine the linkages between landings volume and exvessel prices and revenues, including the sensitivity of Alaska exvessel prices and revenues to changes in landings, the implementation of IFQs, and changes in the Japanese economy. The model simulations indicate that markets could absorb substantially more Sablefish than can be sustainably harves...

According to the nursery size hypothesis, flatfish recruitment is constrained by nursery area. Thus, if resource selection models can be shown to accurately predict the location and geographic extent of flatfish nursery areas, they will become important tools in the management and study of flatfish population dynamics. We demonstrate that some resource selection models derived previously to predict the presence and absence of juvenile flatfishes near shore were applicable to the broader continental shelf. For other age-species groups, derivation of new models for the continental shelf was necessary. Our study was conducted in the western Gulf of Alaska (GoA) during October 2011 on four groups of age-0 juvenile flatfishes: Pacific halibut (Hippoglossus stenolepis), arrowtooth flounder (Atheresthes stomias), northern rock sole (Lepidopsetta polyxystra), and flathead sole (Hippoglossoides elassodon); and three groups of age-1 juvenile flatfishes: northern rock sole, flathead sole, and yellowfin sole (Limanda aspera). Sampling occurred at 33 sites across the continental shelf. Fish were collected using a 3-m beam trawl, and a midwater trawl. Environmental data were collected on sediment composition and water temperature and depth. Many of the age-species groups co-occurred in the Shumagin and Barnabus sea valleys; however, age-0 arrowtooth flounder occurred at more locations than other juveniles, perhaps due to a relatively broad tolerance of environmental conditions and to the utilization of midwater habitat. Thus, the large nursery area of arrowtooth flounder may be one reason why they are currently the most abundant GoA flatfish. In fact, among all species, mean recruitment at age 3 increased with the percent occurrence of age-0 juveniles at the 33 sites, a proxy for relative nursery area, in accordance with the nursery size hypothesis, suggesting that mean recruitment among GoA flatfishes is structured by nursery size.

This article shows the results of testing the technology of producing combined fish farce from deep-sea and demersal fishes. The object of our research is frozen fish, such as Giant grenadier (Albatrossia pectoralis), Alaska plaice (Pleuronectes quadritubercula-tus), Pacific halibut (Hippoglossus stenolepis) and Pacific ocean perch (Sebastes alutus). We found out that a combination of Giant grenadier (Albatrossia pectoralis) and demersal fishes, such as Alaska plaice (Pleuronectes quadrituberculatus), Pacific halibut (Hippoglossus stenolepis) and Pacific ocean perch (Sebastes alutus) in the proportion of 50:50 and a certain salt curing method make it possible to produce high-quality farce systems. We provide a scientific basis for the certain technological parameters defining the formation process of farce system texture depending on the quantity of sodium chloride, temperature of salt curing and length of curing. We found out that sodium chloride at a rate of 1.5-2.0% increases rheological properties of combined fish farce. We outlined conditions and parameters of technological treatment affecting the quality characteristics of ground fish muscle of giant grenadier (Albatrossia pectoralis) with preliminary salt curing. We found out that the highest values of adhesiveness, viscosity, water retention capacity and yield strength belong to experimental samples with 1.5-2.0% of sodium chloride to the raw mass with the temperature of curing plus 20±2°C and reasonable curing time of about 15-20 minutes. Based on the data obtained, it seems promising to produce combined fish farce from deep-sea and demersal fishes, since this method makes it possible to improve their functional and technological properties and to increase consumption of deep-sea and demersal fishes for food.

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.

In fisheries management, ex-ante analysis of fishermen's preferences can provide reliable insights into specific characteristics of regulatory alternatives that are desirable, objectionable, or important, in the judgement of fishermen. This knowledge could facilitate consideration by fishery managers of additional regulatory alternatives with high likelihoods of meeting program objectives, minimal disruption to fishing operations and lifestyles, and high levels of acceptance and compliance from the fishing fleet. In this case study, we interviewed Pacific halibut fishermen (n = 76) in four communities across Southeast Alaska, to document their preferences about different types of data collection methods on their vessels. We demonstrate how to use interviewing to gather preference data from a relatively small group of fishermen and get a reliable snapshot of preferences across an entire region. Pairwise comparisons from interviews were analyzed using a three-stage analytic hierarchy process model. Results characterize the variability of fishermen's preferences about data collection methods.

This report of Ichthyophonus in common sport-caught fishes throughout the marine waters of southcentral Alaska represents the first documentation of natural Ichthyophonus infections in lingcod Ophiodon elongates and yelloweye rockfish Sebastes ruberrimus. In addition, the known geographic range of Ichthyophonus in black rockfish S. melanops has been expanded northward to include southcentral Alaska. Among all species surveyed, the infection prevalence was highest (35%, n = 334) in Pacific halibut Hippoglossus stenolepis. There were no gross indications of high-level infections or clinically diseased individuals. These results support the hypothesis that under typical conditions Ichthyophonus can occur at high infection prevalence accompanied with low-level infection among a variety of fishes throughout the eastern North Pacific Ocean, including southcentral Alaska.

Correspondence between patterns of occupied depth and environmental cycles, called “depth-specific periodic behavior”, has been used to inform management of several flatfishes. However, little is known about depth-specific periodic behavior of Pacific halibut ( Hippoglossus stenolepis ), an important species in recreational, commercial and subsistence fisheries in the eastern North Pacific Ocean. To evaluate depth-specific periodic behavior of Pacific halibut, an approach was developed in which depth data from electronic tags were used to produce four types of complementary plots, including two-dimensional time series of depth, activity level derived from differencing adjacent depth recordings, periodograms, and wavelet transform coefficients. From a visual examination of the plots, daily depth-specific periodic behavior types, including diel, tidal, spawning, semi-lunar and lunar, were assigned to 37 individual Pacific halibut. Overall, the approach used in this study was useful for describing relatively short term depth-specific periodic behavior, but was less informative for understanding relatively long term behavioral patterns. The results suggest that patterns in occupied depth may be related to seasonal activities of Pacific halibut. Specifically, during the summer feeding season, fish most commonly behaved periodically on a diel scale or inactively laid on the seafloor, which was manifested as tidal periodicity as the height of the water column fluctuated above the fish. Both active swimming and inactivity on the seafloor may be related to different foraging strategies. During fall and spring migratory periods and the winter spawning season, no periodicity in depth-specific behavior was most common, which may correspond to directed movement over irregular bathymetry between feeding and spawning locations or to reproductive behaviors. Evidence of an additional reproductive behavior, spawning rises off the seafloor, was also observed during the winter spawning season. This approach for understanding the periodicity of occupied depth of Pacific halibut provides additional insight into the behavior of this iconic species. This knowledge perhaps may be used in the future to inform this species' management, such as refining estimates of susceptibility to capture and examining timing of movement among regulatory areas.