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Microplastics (MPs) and other anthropogenic particles (APs) are pervasive environmental contaminants found throughout marine and aquatic environments. We quantified APs in the edible tissue of black rockfish, lingcod, Chinook salmon, Pacific herring, Pacific lamprey, and pink shrimp, comparing AP burdens across trophic levels and between vessel-retrieved and retail-purchased individuals. Edible tissue was digested and analyzed under a microscope, and a subset of suspected APs was identified using spectroscopy (μFTIR). Anthropogenic particles were found in 180 of 182 individuals. Finfish contained 0.02–1.08 AP/g of muscle tissue. In pink shrimp (Pandalus jordani), the average AP/g was 10.68 for vessel-retrieved and 7.63 for retail-purchased samples; however, APs/g of tissue were higher in retail-purchased lingcod than vessel-retrieved lingcod, signaling possible added contamination during processing from ocean to market. Riverine young adult Pacific lamprey contained higher concentrations of APs (1 AP/g ±0.59) than ocean phase adults (0.60 AP/g ±0.80 and p = 0.08). Particle types identified were 82% fibers, 17% fragments, and 0.66% films. These findings suggest a need for further research into technologies and strategies to reduce microfiber pollution entering the environment. [ABSTRACT FROM AUTHOR]

Natural preservatives make it possible to maintain the quality and safety of fish products, which makes this matter a relevant and promising research area. This article describes the effect of supercritical extracts of marine brown algae Undaria pinnatifida and Ascophyllum nodosum on the quality and safety of fish preserves from Pacific herring in oil and mayonnaise. The experimental samples contained 3% of supercritical extracts of brown algae in the fillings. The samples were stored at 0–5℃ for six months. The authors used standard research methods to study the microbiological, sensory, and physicochemical variables. The safety indicators were established by standard methods in the accredited test center of the Far Eastern Federal University. The acid number was determined by neutralizing free fatty acids with an alcohol solution of sodium hydroxide while the peroxide number was determined by the titrimetric method. The sensory profile included appearance, consistency, color, smell, taste, and the general state of the filling, which were assessed on a five-point scale. The supercritical extracts of brown algae affected the development of microorganisms in both kinds of preserves during storage. The QMAFAnM in the test samples approached that in the control during 6 months of storage, which indicated an opportunity to extend the shelf life of the experimental samples by two months. The experimental samples had lower peroxide and acid numbers, as well as better sensory indicators. In this research, supercritical extracts of U. pinnatifida and A. nodosum improved the quality and safety status of oil and mayonnaise herring preserves. The extracts reduced the accumulation of QMAFAnM and microscopic fungi while slowing down lipid oxidation and hydrolysis.

Microplastics (MPs) and other anthropogenic particles (APs) are pervasive environmental contaminants found throughout marine and aquatic environments. We quantified APs in the edible tissue of black rockfish, lingcod, Chinook salmon, Pacific herring, Pacific lamprey, and pink shrimp, comparing AP burdens across trophic levels and between vessel-retrieved and retail-purchased individuals. Edible tissue was digested and analyzed under a microscope, and a subset of suspected APs was identified using spectroscopy (μFTIR). Anthropogenic particles were found in 180 of 182 individuals. Finfish contained 0.02–1.08 AP/g of muscle tissue. In pink shrimp (Pandalus jordani), the average AP/g was 10.68 for vessel-retrieved and 7.63 for retail-purchased samples; however, APs/g of tissue were higher in retail-purchased lingcod than vessel-retrieved lingcod, signaling possible added contamination during processing from ocean to market. Riverine young adult Pacific lamprey contained higher concentrations of APs (1 AP/g ±0.59) than ocean phase adults (0.60 AP/g ±0.80 and p = 0.08). Particle types identified were 82% fibers, 17% fragments, and 0.66% films. These findings suggest a need for further research into technologies and strategies to reduce microfiber pollution entering the environment.

The purpose of the research is to analyze specifics of Anisakis simplex larvae infection in the body cavity of the lake Pacific herring in Lake Tunaicha (from materials of 1980 to 1995).Materials and methods. Conventional parasitological methods were used for collecting the material. The dissection recorded the number of nematodes in the fish. Parasitological studies of the herring from Lake Tunaicha (southern Sakhalin) were conducted from 1980 to 1995. A total of 4,438 fish caught in the Krasnoarmeyskaya channel and Lake Tunaicha were examined.Results and discussion. The parasite fauna in the herring from Lake Tunaicha included six parasite species of which two nematode species (Anisakis simplex l., Hystorethylacium aduncum l.), one acanthocephala species (Corynosoma strumosum juv.), one trematode species (Brachyphalus crenatus) and two parasitic copepod species (Ergasilus wilsoni and E. hypomesi). Among all the above species, A. simplex larvae were of greatest interest for study. The helminth is a typical species of the Pacific herring and poses a threat to human and animal health. The results of the studies found no difference in the infection of herring females or males in Lake Tunaicha. A change in the infection rate was demonstrated in the herring by age and linear dimensions depending on the fish life cycle (spawning and wintering migration periods). The first cases were recorded for herrings infected with Anisakis sp. larvae sized from 14 cm.

Objective: Changes in abundance and distribution of schooling forage fish, such as the Pacific Sand Lance Ammodytes hexapterus and Pacific Herring Clupea pallasii, can be difficult to document using traditional boat‐based methods, especially in the shallow, nearshore habitats frequented by these species. In contrast, nearshore fish schools are easily observed and quantified from aircraft when light and sea conditions are favorable. We used aerial shoreline surveys to assess interannual variability in the distribution and abundance of schooling forage fish in Prince William Sound, Alaska, during the summers of 2010 and 2012–2022. Methods: During the surveys, aerial observers classified fish schools by their size, species, and (in some cases) age‐class. All observations were georeferenced along the flight path, converted to estimated surface area (m2) based on school diameter, and standardized by effort (shoreline kilometers surveyed). Result: Pacific Herring were widely distributed, and school densities varied annually; there were several spikes in school density of up to 54.38 m2/km interspersed among years of lower average densities (7.73–25.57 m2/km). In contrast, Pacific Sand Lance were usually limited in their distribution to a few predictable locations. School density in these consistent areas varied across years, from a high of 50.98 m2/km in 2010 to a low of 0.15 m2/km in 2017. We validated 88 schools during aerial surveys conducted in 2014–2016 and 2019–2022, of which 76 (86%) were correctly identified to species. Conclusion: Here, we provide indices of Pacific Herring and Pacific Sand Lance school density over time in shallow nearshore coastal areas of Prince William Sound, Alaska. These indices were generated from aerial surveys, which offer an effective alternative to boat‐based surveys for tracking forage fish schools when they occur in shallow and nearshore coastal habitats. Impact statementIn this study, we estimated the density of forage fish schools in Prince William Sound, Alaska by flying surveys along the shoreline and estimating the surface area of fish schools seen for every kilometer of shoreline surveyed. This index can help researchers understand how fish populations vary over time and how they may respond to ecosystem changes. [ABSTRACT FROM AUTHOR]

Objective: The primary objective of this study was to determine the effects of temperature on viral erythrocytic necrosis (VEN) progression under controlled conditions. Secondarily, this study was intended to evaluate the combined effects of temperature and VEN on the Pacific Herring Clupea palasii transcriptome. Methods: The effects of temperature on VEN progression were assessed by waterborne exposure of laboratory‐reared, specific‐pathogen‐free Pacific Herring to tissues homogenates containing erythrocytic necrosis virus (ENV) at 6.9, 9.0, or 13.5°C. Result: Exposure of Pacific Herring to ENV resulted in the establishment of infections characterized by high infection prevalence (89%; 40/45) and mean viral loads (5.5 log10[gene copies/μg genomic DNA]) in kidney tissues at 44 days postexposure. Mean viral loads were significantly higher in fish from the ambient (mean = 9.0°C) and warm (mean = 13.5°C) treatments (6.1–6.2 log10[gene copies/total genomic DNA]) than in fish from the cool (mean = 6.9°C) treatment (4.3 log10[gene copies/μg genomic DNA]). Similarly, the peak proportion of diseased fish was directly related to temperature, with cytoplasmic inclusion bodies detected in 21% of fish from the cool treatment, 52% of fish from the ambient treatment, and 60% of fish from the warm treatment. The mean VEN load in each fish (enumerated as the percentage of erythrocytes with cytoplasmic inclusions) at 44 days postexposure increased with temperature from 15% in the cool treatment to 36% in the ambient treatment and 32% in the warm treatment. Transcriptional analysis indicated that the number of differentially expressed genes among ENV‐exposed Pacific Herring increased with temperature, time postexposure, and viral load. Correlation network analysis of transcriptomic data showed robust activation of interferon and viral immune responses in the hepatic tissue of infected individuals independent of other experimental variables. Conclusion: Results from this controlled laboratory study, combined with previous observations of natural epizootics in wild populations, support the conclusion that temperature is an important disease cofactor for VEN in Pacific Herring. Impact statementViral erythrocytic necrosis is a temperature‐dependent disease in Pacific Herring. These findings provide insights into the future impacts of climate change on coastal marine ecosystems and a critical marine forage fish. [ABSTRACT FROM AUTHOR]

The data on linear growth and the scale annuli forming are generalized for pacific herring in Peter the Great Bay. The growth zone on scales begins in April-May, whereas the annuli of slow growth are formed from October to January. The phenological season of active somatic growth also starts in April-May for herring in this area, the largest gains of the body length are detected in late summer — early autumn, and the active growth ends by NovemberDecember. Size diversity for young fish depends on starting conditions of growth in the first year of life and the timing of puberty. The diversity increases for adults because of the growth accelerating for the fish dwelling in local favorable environments with longer growing season.

Anthropogenic climate change is projected to affect marine ecosystems by challenging the environmental tolerance of individuals. Marine fishes may be particularly vulnerable to emergent climate stressors during early life stages. Here we focus on embryos of Pacific herring (Clupea pallasii), an important forage fish species widely distributed across the North Pacific. Embryos were reared under a range of temperatures (10-16°C) crossed with two pCO2 levels (600 and 2000 matm) to investigate effects on metabolism and survival. We further tested how elevated pCO2 affects critical thermal tolerance (CTmax) by challenging embryos to short-term temperature fluctuations. Experiments were repeated on embryos collected from winter and spring spawning populations to determine if spawning phenology corresponds with different limits of environmental tolerance in offspring. We found that embryos could withstand acute exposure to 20°C regardless of spawning population or incubation treatment, but that survival was greatly reduced after 2-3 hours at 25°C. We found that pCO2 had limited effects on CTmax. The survival of embryos reared under chronically warm conditions (12°, 14°, or 16°C) was significantly lower relative to 10°C treatments in both populations. Oxygen consumption rates (MO2) were also higher at elevated temperatures and pCO2 levels. However, heart contraction measurements made 48 hours after CTmax exposure revealed a greater increase in heart rate in embryos reared at 10°C compared to 16°C, suggesting acclimation at higher incubation temperatures. Our results indicate that Pacific herring are generally tolerant of pCO2 but are vulnerable to acute temperature stress. Importantly, spring-spawning embryos did not clearly exhibit a higher tolerance to heat stress compared to winter offspring. [ABSTRACT FROM AUTHOR]

Based on long-term data on Pacific herring in the Peter the Great Bay, it has been established that the growth zone on scales begins in April and May, whereas the annuli form between October and January. The phenological season of active somatic growth starts in April and May for herring in this area, the largest body length gains are detected in late summer and early autumn, and active growth ends by November and December. Size diversity for young fish depends on starting conditions for growth in the first year of life and the timing of puberty. Size diversity increases in adult fish because of the accelerated growth for the fish dwelling in local favorable habitats with longer growth seasons or internal reserves of the body. [ABSTRACT FROM AUTHOR]

Causes of population collapse and failed recovery often remain enigmatic in marine forage fish like Pacific herring (Clupea pallasii) that experience dramatic population oscillations. Diseases such as ichthyophoniasis are hypothesized to contribute to these declines, but lack of long-term datasets frequently prevents inference. Analysis of pathogen surveillance and population assessment datasets spanning 2007–2019 indicate that the age-based prevalence estimate of Ichthyophonus infection was, on average, 54% greater among a collapsed population of Pacific herring (Prince William Sound, Alaska, USA) as compared to a nearby population (Sitka Sound, Alaska, USA) that is relatively robust. During the study years, the age-based infection prevalence ranged from 14 to 44% in Prince William Sound and 5 to 33% in Sitka Sound. At both sites, the age-based infection prevalence declined over time, with an average decrease of 7% per year. Statistical analyses indicated that infection prevalence between the two populations was reduced by regional factors affecting both sites, and that these factors were independent of herring density. Infection prevalence in both populations was positively correlated with herring age and negatively correlated with the Pacific Decadal Oscillation. This study demonstrates how synthesis of environmental, stock assessment, and disease assessment data can be leveraged to elucidate epidemiological trends in diseases of wild fish. [ABSTRACT FROM AUTHOR]

Anthropogenic climate change is projected to affect marine ecosystems by challenging the environmental tolerance of individuals. Marine fishes may be particularly vulnerable to emergent climate stressors during early life stages. Here we focus on embryos of Pacific herring (Clupea pallasii), an important forage fish species widely distributed across the North Pacific. Embryos were reared under a range of temperatures (10-16°C) crossed with two pCO2 levels (600 and 2000 μatm) to investigate effects on metabolism and survival. We further tested how elevated pCO2 affects critical thermal tolerance (CTmax) by challenging embryos to short-term temperature fluctuations. Experiments were repeated on embryos collected from winter and spring spawning populations to determine if spawning phenology corresponds with different limits of environmental tolerance in offspring. We found that embryos could withstand acute exposure to 20°C regardless of spawning population or incubation treatment, but that survival was greatly reduced after 2-3 hours at 25°C. We found that pCO2 had limited effects on CTmax. The survival of embryos reared under chronically warm conditions (12°, 14°, or 16°C) was significantly lower relative to 10°C treatments in both populations. Oxygen consumption rates (MO2) were also higher at elevated temperatures and pCO2 levels. However, heart contraction measurements made 48 hours after CTmax exposure revealed a greater increase in heart rate in embryos reared at 10°C compared to 16°C, suggesting acclimation at higher incubation temperatures. Our results indicate that Pacific herring are generally tolerant of pCO2 but are vulnerable to acute temperature stress. Importantly, spring-spawning embryos did not clearly exhibit a higher tolerance to heat stress compared to winter offspring.

A limit reference point (LRP) is defined as a level of biomass to be avoided with high probability, which should be selected to protect fish stocks from "serious harm". We present an evidence-based approach for diagnosing serious harm and apply it to the selection of LRPs for five Pacific herring (Clupea pallasii) stocks in British Columbia (BC). Natural mortality (M) is estimated to be time varying and has increased more than it declined over the past three decades, which presents a challenge for estimation of equilibrium reference points based on maximum sustainable yield. We present a semi-empirical approach for developing LRPs, which examines surplus production in relation to spawning biomass to determine whether there is evidence for low productivity, low biomass (LP-LB) states consistent with serious harm. Three stocks showed evidence of persistent LP-LB states that resulted in periods of fishery closures. Based on these results, an LRP of 30% of unfished spawning biomass (0.3B0) was recommended and adopted for management of all five major stocks of BC Pacific herring. [ABSTRACT FROM AUTHOR]

Recruitment of estuarine organisms can vary dramatically from year to year with abiotic and biotic conditions. The San Francisco Estuary (California, USA) supports a dynamic ecosystem that receives freshwater flow from numerous tributaries that drain one of the largest watersheds in western North America. In this study, we examined distribution and habitat use of two forage fish larvae of management interest, Longfin Smelt Spirinchus thaleichthys and Pacific Herring Clupea pallasii, during a low-flow and a high-flow year to better understand how their rearing locations (region and habitat) may affect their annual recruitment variability. During the low-flow year, larval and post-larval Longfin Smelt were distributed landward, where suitable salinity overlapped with spawning habitats. During the high-flow year, larval Longfin Smelt were distributed seaward, with many collected in smaller tributaries and shallow habitats of San Francisco Bay. Local spawning and advection from seaward habitats were speculated to be the primary mechanisms that underlie larval Longfin Smelt distribution during the high-flow year. Larval Pacific Herring were more abundant seaward in both years, but a modest number of larvae were also found landward during the low-flow year. Larval Pacific Herring abundance was lower overall in the high-flow year, suggesting advection out of the area or poor recruitment. Future monitoring and conservation efforts for Longfin Smelt and Pacific Herring should recognize that potential mechanisms underlying their recruitment can vary broadly across the San Francisco Estuary in any given year, which suggests that monitoring and research of these two species expand accordingly with hydrologic conditions that are likely to affect their spawning and larval rearing distributions.

Atlantic herring (Clupea harengus) and Pacific herring (C. pallasii) are sister species that split from a common ancestor about 2 million years ago. Balsfjord, a subarctic fjord in Northern Norway, harbors an outpost population of Pacific herring within the range of the Atlantic herring. We used whole genome sequencing to show that gene flow from Atlantic herring into the Balsfjord population has generated a stable hybrid population that has persisted for thousands of generations. The Atlantic herring ancestry in Balsfjord was estimated in the range 25–26%. The old age and large proportion of introgressed regions suggest there are no obvious genetic incompatibilities between species. Introgressed regions were widespread in the genome and large, with some in excess of 1 Mb, and they were overrepresented in low-recombination regions. We show that the distribution of introgressed material is non-random; introgressed sequence blocks in different individuals are shared more often than expected by chance. Furthermore, introgressed regions tend to show elevated divergence (F ST) between Atlantic and Pacific herring. Together, our results suggest that introgression of genetic material has facilitated adaptation in the Balsfjord population. The Balsfjord population provides a rare example of a stable interspecies hybrid population that has persisted over thousands of years. [ABSTRACT FROM AUTHOR]

Biological characteristics and dynamics of stocks and fishery are considered for pacific herring in the South-Kuril fishing district on the data of research surveys and fishery statistics for 2014–2021. Features of the herring wintering and the rates of linear growth and maturation are analyzed. The stock recovery on the shelf of southern Kuril Islands is detected that corresponds to recovery of the whole Sakhalin-Hokkaido population of this species. A sharp increase of the herring abundance in this area is observed nowadays for the first time since the 1940s. According to results of cohort modeling, the commercial biomass of herring in the South-Kuril district has increased from several tens of ton in 2014–2017 to 9,700 t in 2021. The basis of the stock consists of fish aged 3–4 years, 25–29 cm long, that prevailed (76–82 %) in the catches in 2020–2021. The stock increasing is accompanied by expansion of the herring distribution, the aggregations density increasing in spring, complication of the size and age structure, heightening of the average size and age in catches of fixed nets in the spawning season, mass appearance of the juveniles in catches of bottom trawl survey in 2020, and progressive growth of the landing in 2018–2021. The usual place for the herring wintering in this area is the eastern side of the deep-water canyon off the western coast of Kunashir Island. According to updated data, the spawning migrations of herring begin in early-middle April. The producers migrate mainly from the wintering sites to the southern Kunashir Strait, and then along the Pacific side of Kunashir Island to their spawning grounds. The migration along the Okhotsk Sea coast is secondary. The spawning occurs at Kunashir Island in the period from late April to middle May (the timing varies from year to year; the peak of spawning was observed in early May in 2020, but in middle May in 2021). Unlike other populations, the herring of the South-Kuril area do not make extended migrations after the spawning, but feed on adjacent shelf for a long time. Fishery on herring develops rapidly in the South-Kuril fishing district: the annual catch was 140 t in 2018, but reached 1010 t in 2021. Trawl fishery of pacific herring has the highest prospects for coming years. The fishing by Danish seines can be intensified in the waters between Kunashir and Shikotan in the pre-spawning period, though the landing by fixed nets on the spawning grounds can be stabilized if the number of coastal fishing teams will be increased.

Understanding the response of predators to ecological change at multiple temporal scales can elucidate critical predator–prey dynamics that would otherwise go unrecognized. We performed compound‐specific nitrogen stable isotope analysis of amino acids on 153 harbor seal museum skull specimens to determine how trophic position of this marine predator has responded to ecosystem change over the past century. The relationships between harbor seal trophic position, ocean condition, and prey abundance, were analyzed using hierarchical modeling of a multi‐amino‐acid framework and applying 1, 2, and 3 years temporal lags. We identified delayed responses of harbor seal trophic position to both physical ocean conditions (upwelling, sea surface temperature, freshwater discharge) and prey availability (Pacific hake, Pacific herring, and Chinook salmon). However, the magnitude and direction of the trophic position response to ecological changes depended on the temporal delay. For example, harbor seal trophic position was negatively associated with summer upwelling but had a 1‐year delayed response to summer sea surface temperature, indicating that some predator responses to ecosystem change are not immediately observable. These results highlight the importance of considering dynamic responses of predators to their environment as multiple ecological factors are often changing simultaneously and can take years to propagate up the food web. [ABSTRACT FROM AUTHOR]

The biological characteristics of Pacific herring and the dynamics of herring stocks and fishery in the Southern Kuril fishery zone are considered based on the data of observations and fishery statistics for 2014–2021. The herring abundance off the southern Kuril Islands currently shows a sharp increase. According to the modeling results, the commercial herring biomass grew from several dozens of tons in 2014–2017 to 9700 t in 2021. The major part of the stock consisted of age 3–4 years, 25–29-cm-long individuals that accounted for 76–82% of the total number in catches in 2020–2021. The increasing trend of the stock is confirmed by the following processes: the expansion of the areas of herring occurrence and by the increase in the aggregation density of herring during surveys in spring; the complication of the size and age structure and the increase in the average size and age in stake net catches during the spawning season; the mass occurrence of the young-of-the-year in catches of the bottom trawl survey 2020; and the progressive increase in the annual catch values in 2018–2021. The data on timing and pattern of pre-spawning herring migrations over the Kunashir Island shelf has been updated. The onset of these migrations occurs in the first or second 10-day periods of April. The major part of spawners move, first, from the wintering grounds to the southern Kunashir Strait and then along the Pacific side of Kunashir Island to their spawning grounds. The most likely location of the herring wintering ground is the eastern side of the deep-sea strait off the western Kunashir Island coast. Herring in the waters off the southern Kuril Islands are currently harvested with midwater trawls, Danish seines, and small stake nets during the spawning season. The annual catches increased from 140 t in 2018 to 1010 t in 2021. Trawl fishery for Pacific herring will play the major role in harvesting the commercial resources in the coming years. [ABSTRACT FROM AUTHOR]

Abstract Food limitation can dampen the survival and growth of fish species during early development. To investigate prey diversity important to the planktivorous larval longfin smelt (Spirinchus thaleichthys) and Pacific herring (Clupea pallasii) from the San Francisco Estuary, we used DNA metabarcoding analysis of the cytochrome oxidase I gene on the guts of these fishes and on environmental zooplankton samples, in comparison with results from abundance analyses of zooplankton samples. Overall, both fish consumed the prey that were commonly available and relatively abundant: Diets were dominated by arthropods but also included soft‐bodied and difficult to identify organisms. Prey taxa substantially overlapped between the two species (Schoener's index = 0.66), and alpha diversity analysis suggested high variability in the content of guts from different individuals. Abundant prey taxa in both fish species included the copepods Eurytemora carolleeae, Acanthocyclops americanus, and A. robustus; Acanthocyclops spp. are difficult to distinguish morphologically. Differential abundance analysis suggested that both species consumed the most abundant zooplankton in lower proportions than their availability in the environment. A few uncommon prey observed in the diets may hint at feeding strategies employed by the larvae, such as herring DNA in the longfin smelt diets, suggesting feeding on eggs near substrates or schooling behavior. Herring consumed the small (

The Pacific herring (Clupea pallasii) is one of the most important species in the commercial fisheries distributed in the North Pacific Ocean and the northeastern European seas. This teleost has marine and lake ecological forms a long its distribution in the Holarctic. However, the level of genetic differentiation between these two forms is not well known. In the present study, we used ddRAD-sequencing to genotype 54 specimens from twelve wild Pacific herring populations from the Kara Sea and the Russian part of the northwestern Pacific Ocean for unveiling the genetic structure of Pacific herring. We found that the Kara Sea population is significantly distinct from Pacific Ocean populations. It was demonstrated that lake populations of Pacific herring differ from one another as well as from marine specimens. Our results show that fresh and brackish water Pacific herring, which inhabit lakes, can be distinguished as a separate lake ecological form. Moreover, we demonstrate that each observed lake Pacific herring population has its own and unique genetic legacy.

The Pacific herring (Clupea pallasii) is one of the most important species in the commercial fisheries distributed in the North Pacific Ocean and the northeastern European seas. This teleost has marine and lake ecological forms a long its distribution in the Holarctic. However, the level of genetic differentiation between these two forms is not well known. In the present study, we used ddRAD-sequencing to genotype 54 specimens from twelve wild Pacific herring populations from the Kara Sea and the Russian part of the northwestern Pacific Ocean for unveiling the genetic structure of Pacific herring. We found that the Kara Sea population is significantly distinct from Pacific Ocean populations. It was demonstrated that lake populations of Pacific herring differ from one another as well as from marine specimens. Our results show that fresh and brackish water Pacific herring, which inhabit lakes, can be distinguished as a separate lake ecological form. Moreover, we demonstrate that each observed lake Pacific herring population has its own and unique genetic legacy. [ABSTRACT FROM AUTHOR]

Recent changes of the main oceanographic, chemical, and biological parameters of the Okhotsk Sea ecosystem are considered briefly for the last decades (2000–2010s), mostly on the data obtained in marine expeditions conducted by Pacific Fish. Res. Center (TINRO) annually. Since the mid-2000s, anomalous oceanographic conditions were formed there with prevailing heightened temperature in all layers of the sea and lowered ice cover caused by changes in the atmosphere circulation with northward shift of cyclones tracks in winter and weakening of winter monsoon. The ice cover was below the normal value every year since 2004. In the warmer winter conditions, producing of the high-density water on the northern shelf decreased from 3.2–7.8 . 103 km3 in 1998–2002 to 1.2 . 103 km3 on average in 2004–2015, and the water with density sq > 26.8 was not formed at all in 2007–2009, 2011, and 2014–2015. As the result, winter convection, including the slope convection, became weaker and shallower and ventilated worse the water column, so dissolved oxygen content decreased in the lower portion of the intermediate layer, usually ventilated by slope convection. For the core of the intermediate layer (isopycnal surface 27.0 σθ), positive trend of temperature is estimated as +0.04…+0.16 o/decade, by areas, while the trend of dissolved oxygen content is negative: –0.07…–0.14 mL/L.decade, by areas. From the other hand, spring phytoplankton bloom became less intensive, presumably because of poorer upward flux of nutrients in conditions of weaker vertical mixing, and zooplankton biomass decreased, particularly for phytophages. However, these changes did not cause significant response in fluctuations of stocks for the main commercial fish and crab species. The largest stock of walleye pollock had cyclic fluctuations driven mostly by intra-population regulations, the stocks of pacific herring were rather stable, and the stocks of deep-water fish species, as flounders and halibuts had a slight tendency to growth, possibly because of better conditions for reproduction. Indeed, the densest aggregations of greenland halibut shifted from the depth of 600–700 m to 500–600 m that may be caused by de-oxygenizing of the lower portion of the intermediate layer. Crabs abundance also had positive dynamics obviously because of the effect of protective measures for red king crab in the 2009–2012, though its biomass continued to grow even after restoring the commercial landings. There is concluded that recent changes in the macroecosystem of the Okhotsk Sea correspond to the conception of the sub-polar ecosystems transformation under climate warming toward decreasing of their productivity and increasing of their functioning efficiency that was proposed earlier for the Japan Sea. Thus, from position of commercial exploitation of marine biological resources, the modern reconstruction of the Okhotsk Sea ecosystem under the climate change impact could be considered as a positive process.

Using ten microsatellite loci, the analysis of genetic variability and differentiation of the Pacific herring Clupea pallasii over a wide geographic range in the Sea of Okhotsk, the Bering, Chukchi, Kara, Barents, and White seas was performed. A similar level of genetic variability is shown for the herring belonging to three geographical subspecies. The genetic structure at a large scale is most pronounced between the three geographical subspecies of herring, with the different level of genetic differentiation within each of the subspecies. Herring of the Pacific distribution range is differentiated only at the level of large basins, the Sea of Okhotsk and Bering Sea, which indicates a significant level of gene exchange, as in the southeastern part of the Barents Sea and in the Kara Sea. However, the gene flow in the White Sea herring is limited to a very small spatial scale. [ABSTRACT FROM AUTHOR]

During 2014-2016, the northeast Pacific Ocean experienced a large-scale marine heatwave (nicknamed 'The Blob'), an event that was associated with die-offs of several marine bird species. The Marbled Murrelet Brachyramphus marmoratus is a small seabird in this region for which we evaluated trends in abundance--for the purposes of conservation planning--during radar surveys at 58 sites in coastal British Columbia, from 1996 to 2018, and for which we determined whether trends may have been affected by 'The Blob'. A hierarchical Bayesian model allowed us to separate long-term trends from short-term annual fluctuations ('year effects') that might have resulted from changes in ocean conditions, and it also allowed us to test whether predicted regional counts were associated with two indices of marine conditions: (1) measured abundance of a prey species, Pacific Herring Clupea pallasii; and (2) sea surface temperature (SST). Province-wide mean annual rate of change in counts was significantly negative, with a posterior median of -0.023 (95% credible interval: -0.033, -0.014); mean rate of change in counts per year was negative for all six Marbled Murrelet Conservation Regions; and trends were significantly negative at the Central Mainland Coast, East Vancouver Island, Haida Gwaii, and the South Mainland Coast conservation regions. Year effects during or after 'The Blob' at West and North Vancouver Island (2016) and East Vancouver Island (2018) conservation regions were not statistically significant. Mean predicted regional counts of murrelets showed weakly positive correlations with age two herring recruitment, and no consistent associations with SST. These results indicate that the marine heatwave did not strongly affect forest-bound murrelets and are consistent with the hypothesis that ongoing loss of terrestrial nesting habitat is associated with population declines of Marbled Murrelets in British Columbia. [ABSTRACT FROM AUTHOR]

Increasing green house gas emissions are expected to raise surface seawater temperatures and lead to locally intensified ocean acidity in the U.S. Pacific Northwest. Pacific herring (Clupea pallasi) are ecologically and economically important forage fish species native to this region. While the impacts of ocean acidification and ocean warming on organism physiology have been extensively studied, less is known on how concurrent climate change stressors will affect marine fish. Therefore, our study focused on the combined effects of ocean acidification and warming on Pacific herring early life history stages. Pacific herring embryos were incubated under a factorial design of two temperature (10°C or 16°C) and two pCO2 (600 μatm or 1200 μatm) treatments from fertilization until hatch (6 to 15 days depending on temperature). Elevated pCO2 was associated with a small increase in embryo mortality. Elevated temperature, as a single stressor, generated greater embryo mortality and embryo heart rates, larger yolk areas upon hatch, lower hatching success, and shorter larval lengths; compared with the same parameters measured under ambient temperature. The interaction of elevated temperature and pCO2 was associated with greater embryo heart rates and yolk areas compared to ambient conditions. This study suggests that while temperature is the primary global change stressor affecting Pacific herring embryology, interaction effects with pCO2 could introduce additional physiological challenges.

The timing of reproduction influences key evolutionary and ecological processes in wild populations. Variation in reproductive timing may be an especially important evolutionary driver in the marine environment, where the high mobility of many species and few physical barriers to migration provide limited opportunities for spatial divergence to arise. Using genomic data collected from spawning aggregations of Pacific herring (Clupea pallasii) across 1600 km of coastline, we show that reproductive timing drives population structure in these pelagic fish. Within a specific spawning season, we observed isolation by distance, indicating that gene flow is also geographically limited over our study area. These results emphasize the importance of considering both seasonal and spatial variation in spawning when delineating management units for herring. On several chromosomes, we detected linkage disequilibrium extending over multiple Mb, suggesting the presence of chromosomal rearrangements. Spawning phenology was highly correlated with polymorphisms in several genes, in particular SYNE2, which influences the development of retinal photoreceptors in vertebrates. SYNE2 is probably within a chromosomal rearrangement in Pacific herring and is also associated with spawn timing in Atlantic herring (Clupea harengus). The observed genetic diversity probably underlies resource waves provided by spawning herring. Given the ecological, economic and cultural significance of herring, our results support that conserving intraspecific genetic diversity is important for maintaining current and future ecosystem processes. [ABSTRACT FROM AUTHOR]

Pacific and Atlantic herring populations (genus Clupea) commonly experience episodic collapse and recovery. Recovery time durations are of great importance for the sustainability of fisheries and ecosystems. We collated information from 64 herring populations to characterize herring fluctuations and determine the time scales at low biomass and at high and low recruitment, and use generalized linear models and Random Survival Forests to identify the most important bottom‐up, top‐down and intrinsic factors influencing recovery times. Compared to non‐forage fish taxa, herring decline to lower minima, recover to higher maxima and show larger changes in biomass, implying herring are more prone to booms and busts than non‐forage fish species. Large year classes are more common in herring, but occur infrequently and are uncorrelated among regionally grouped stocks, implying local drivers of high recruitment. Management differs between Pacific and Atlantic herring fisheries, where at similarly low biomass, Pacific fisheries tend to be closed while Atlantic fisheries remain open. This difference had no apparent effect on herring recovery times, which averaged 11 years, although most stocks with longer recovery periods had not yet recovered at the end of the observation period. Biomass recovery is best explained by median recruitment and variability in sea surface height anomalies and sea surface temperatures—higher variability leads to shorter recovery times. In addition, the duration of recruitment failure is closely linked with low biomass. While recovery times rely on the nature of the relationship between spawning biomass and recruitment, they are still largely governed by complex and uncertain processes. [ABSTRACT FROM AUTHOR]

A comparative study of the nutritional value of salmon caviar and that of Pacific herring has been conducted showing that the herring caviar nutritional value is not inferior to the salmon one. One of the directions of processing caviar raw materials is the production of pasty products: pates, spreads, pastes, sauces, creams and oils. The successful development of such products using caviar raw materials is only possible by conducting regular analysis of food values, the study of structuring and emulsifying properties, which are currently not sufficiently studied. The functional and technological properties of Pacific herring have been investigated: water-binding capacity (WBC), water-holding capacity (WHC), emulsifying capacity (EC) etc. It has been experimentally established that the stability of emulsion systems from Pacific herring caviar affects the type of pretreatment of raw materials. Emulsions with fresh caviar have high functional and technological properties. Fresh caviar is characterized by the high rate of WBC equal to 76.90 %. In the process of cold storage there is a decrease in the WBC, within four weeks the decline is 70.17 %, by the end of three months storage WBC is reduced to 51.82 %. Studies have shown that herring caviar has a high EC (100 %), which is not changed during cold storage. The use of frozen Pacific herring caviar as the emulsion allows obtain systems with a high emulsifying ability, i. e. the freezing does not reduce their capacity to hold water and fat phases in the system. However, the stability of emulsion systems using frozen Pacific herring caviar is lower than fresh. In addition, the longer term cold storage of caviar, the lower the stability of emulsion systems prepared with its use. Caviar salting with the salt content 3.5 % leads to a slight decrease in the functional and technological properties of raw materials. Thus, studies have shown the promising use of Pacific herring caviar in the technology of emulsified products both as a structurant, and a highly valuable food component.

State of the demersal fish community in the northwestern Japan Sea in the period 1978-1990 is considered on the data of bottom trawl surveys. Mean total biomass of the demersal fish in the USSR economic zone in those times is estimated as 1.106. 106 t. The bulk of fish community was formed by the families Gadidae, Pleuronectidae, Clupeidae, Hexagrammidae, and Cottidae with summary portion 95.1 % by biomass and 84.8 % by number. The most abundant fish species were walleye pollock Theragra chalcogramma (44.8 % of the biomass), scale-eye plaice Acanthopsetta nadeshnyi (12.2 %), pacific herring Clupea pallasii (8.6 %), blackfin flounder Glyptocephalus stelleri (7.7 %), pacific cod Gadus macrocephalus (4.7 %), and arabesque greenling Pleurogrammus azonus (4.6 %), portions of other species didn’t exceed 3 %. The summary portion of flounders (23 species) was 28.0 %, by biomass. Scale-eye plaice dominated among them (on average 135.4. 103 t), other mass flounders were the blackfin flounder (84.8. 103 t), yellowstriped flounder Pseudopleuronectes herzensteini (29.0. 103 t), and yellowfin sole Limanda aspera (13.2. 103 t) though the latter species had dominated there in the 1930s.

Throughout a 20 year biosurveillance period, viral hemorrhagic septicemia virus was isolated in low titers from only 6/7355 opportunistically sampled adult Pacific herring, reflecting the typical endemic phase of the disease when the virus persists covertly. However, more focused surveillance efforts identified the presence of disease hot spots occurring among juvenile life history stages from certain nearshore habitats. These outbreaks sometimes recurred annually in the same temporal and spatial patterns and were characterized by infection prevalence as high as 96%. Longitudinal sampling indicated that some epizootics were relatively transient, represented by positive samples on a single sampling date, and others were more protracted, with positive samples occurring throughout the first 10 weeks of the juvenile life history phase. These results indicate that viral hemorrhagic septicemia (VHS) epizootics in free-ranging Pacific herring C. pallasii are more common than previously appreciated; however, they are easily overlooked if biosurveillance efforts are not designed around times and locations with high disease potential.

A qualitative understanding of the long‐term variation in the population dynamics of Yellow Sea (YS) herring is particularly important for clarifying the evolutionary processes and driving mechanisms of the YS large marine ecosystem. Unfortunately, because of a lack of long‐term, continuous, and simultaneous monitoring data, the specific driving processes and mechanisms of climate effects on the population dynamics of YS herring remain largely unknown. In response to this scientific issue, we preliminarily propose the idea of reconstructing long‐term changes in YS herring abundance over the past 590 years (AD 1417–2004) based on historical documents and attempt to explore the impacts of climate on the population. Our results show that YS herring abundance maintained at a relatively high level from AD 1417 to 1870 (during the Little Ice Age); in contrast, the population declined significantly from AD 1870 to 2004 at different rates. In addition, we also found that there were strong relationships between the population abundance of YS herring and the Pacific decadal oscillation (PDO) and drought/flood cycles. We suggest that the fluctuations in YS herring abundance may be influenced by ocean–climatic circulation shifts throughout the North Pacific, especially the PDO. [ABSTRACT FROM AUTHOR]

The article focuses on herring was one of the most important fish in Europe in the late Middle Ages and contains protein, up to two years of preservation and cheap from the 15th century, the herring formed one core component of the diet. It mentions importance of quality control of the herring became although hinted at by Angelika Lampen or Carsten Jahnke and food hygiene has become more important.

Fisheries surveys are required to assess the status of fish populations but are rarely evaluated to determine which data provide most information for least cost. We develop such a method focused on Pacific herring (Clupea pallasii) in Prince William Sound, Alaska. This population collapsed in 1992–93 and an intensive monitoring programme has been developed to assess why herring have not yet recovered, including the development of a Bayesian stock assessment model. We conducted a Monte-Carlo simulation study that calculated the deterioration in assessment performance when each survey was excluded, which allowed us to assess the trade-off between cost and improvement in model performance from including each survey data. For $10,000 a year the disease survey reduces bias and imprecision in current biomass by 34% on average, increases model reliability by 22%, and decreases by 31% the probability of a false management conclusion related to regulating the fishery. For $350,000 a year the diver survey reduces bias and imprecision by 12%, increases model reliability by 6%, and decreases the probability of a false management conclusion by 23%. The framework presented here can be used in other fisheries to weigh the costs and benefits of alternative sampling programmes in estimating current biomass. [ABSTRACT FROM AUTHOR]

Assessment of risk from industrial developments often relies on simple habitat descriptions for focal species. However, simple habitat metrics may not be accurate predictors of locations that species actually use. Understanding the nature of habitat is particularly pressing for estuaries, as they are among the most degraded ecosystems globally but provide critical rearing habitat for many species, including Pacific salmon.Canadian environmental impact assessment approaches use simple habitat‐type models to assess risk from developments and assume that different species of salmon rely on the same habitat. This study asked what combination of habitat type and biophysical covariates best predicted use of estuary habitat by juvenile salmon and two dominant small pelagic fish.Fish were sampled via purse seine throughout the Skeena River estuary (British Columbia, Canada) for 2 years across different habitat types (eelgrass, open water, sandy banks, and rocky shores). Simple habitat‐type models were compared with models with more complex biophysical variables to predict the variability in relative abundance of juvenile Chinook (Oncorhynchus tshawytscha), coho (Oncorhynchus kisutch), and sockeye (Oncorhynchus nerka) salmon, along with pelagic fish species Pacific herring (Clupea pallasii) and surf smelt (Hypomesus pretiosus).The combination of variables that best predicted abundance differed across fish species. Pelagic fish were associated with near‐shore sites, increased temperature (herring), and increased salinity (smelt). Juvenile coho and sockeye salmon (but not Chinook), were more abundant in higher turbid waters. Chinook and sockeye salmon used eelgrass habitat more frequently than other habitat types, whereas coho salmon were more abundant in areas with high macroalgae cover. Models with these variables had greater predictive power than those using habitat type alone for juvenile salmon.Simple classifications of estuary habitat currently used in environmental risk assessment may not reflect the complex nature of fish–habitat associations. Understanding biophysical factors associated with estuary fish abundance can inform management of estuary habitat to support their nursery function for important fish. [ABSTRACT FROM AUTHOR]

Wild specimens are often collected in challenging field conditions, where samples may be contaminated with the DNA of conspecific individuals. This contamination can result in false genotype calls, which are difficult to detect, but may also cause inaccurate estimates of heterozygosity, allele frequencies and genetic differentiation. Marine broadcast spawners are especially problematic, because population genetic differentiation is low and samples are often collected in bulk and sometimes from active spawning aggregations. Here, we used contaminated and clean Pacific herring (Clupea pallasi) samples to test (a) the efficacy of bleach decontamination, (b) the effect of decontamination on RAD genotypes and (c) the consequences of contaminated samples on population genetic analyses. We collected fin tissue samples from actively spawning (and thus contaminated) wild herring and nonspawning (uncontaminated) herring. Samples were soaked for 10 min in bleach or left untreated, and extracted DNA was used to prepare DNA libraries using a restriction site‐associated DNA (RAD) approach. Our results demonstrate that intraspecific DNA contamination affects patterns of individual and population variability, causes an excess of heterozygotes and biases estimates of population structure. Bleach decontamination was effective at removing intraspecific DNA contamination and compatible with RAD sequencing, producing high‐quality sequences, reproducible genotypes and low levels of missing data. Although sperm contamination may be specific to broadcast spawners, intraspecific contamination of samples may be common and difficult to detect from high‐throughput sequencing data and can impact downstream analyses. [ABSTRACT FROM AUTHOR]

In the Gulf of Alaska (GOA), forage fish species, such as age-0 walleye pollock (Gadus chalcogrammus), capelin (Mallotus villosus), Pacific herring (Clupea pallasii), and mesopelagic fishes (e.g. Myctophidae), are ecologically important as both consumers of zooplankton, and as prey for fish, seabirds, and marine mammals. As part of the Gulf of Alaska Integrated Ecosystem Research Program, an acoustic-trawl survey was conducted in the summer and fall of 2011 and 2013 to quantify variability in species composition, density, and distributions of forage fish over the continental shelf and slope in the central and eastern regions of the GOA. The forage fish community in 2011 was characterized by the absence of age-0 pollock and lower densities of capelin, herring, and mesopelagics compared to observations in 2013. Age-0 pollock were abundant across both regions in summer 2013, but were rarely observed in fall. In contrast, summer observations of herring were rare, while aggregations of herring were observed over the eastern GOA shelf in fall of both years. Seasonal changes in community composition are attributed to the transport of age-0 pollock from offshore waters in summer to nearshore waters in fall, and to immigration of herring to the eastern GOA shelf in fall. Forage fish spatial patterns varied within and between regions due to intra- and interspecific differences in horizontal and vertical distributions that were correlated with bottom depth. Observed spatial and temporal variability in community composition and distributions of forage fish species may potentially impact predator foraging in the GOA, as well as the effectiveness of monitoring to detect changes in forage fish biomass. [ABSTRACT FROM AUTHOR]

To clarify nursery habitat use for larval and juvenile Pacific herring Clupea pallasii, we collected eggs, larvae, and juveniles at several sampling sites in inner Miyako Bay from 2012 to 2016. Adult C. pallasii used sea grass beds on the west side of inner Miyako Bay as a spawning area. In contrast, their offspring grew up to approximately 100 mm in total length (TL) on the east side of the inner bay, where they stayed until July. C. pallasii seemed to leave the nursery area on the east side of the bay with the rise in temperature in August. Therefore, C. pallasii shifted habitats with ontogenetic development, from the west side of the inner bay in the egg stage, to the east side of the inner bay in the larval and early juvenile stages, and then to the central bay area in the later juvenile stage. Environmental surveys showed lower salinity near the bottom of the east side than the west side of inner Miyako bay, suggesting that larval and juvenile C. pallasii appeared to use the area with low salinity on the east side of Miyako Bay as a nursery. [ABSTRACT FROM AUTHOR]

From June to August 2012, we conducted over 500 h of visual surveys from Cormorant Island, British Columbia, to determine behaviour and habitat use patterns of nearby cetaceans. Seven species were documented, but Minke Whales (Balaenoptera acutorostrata) were by far the most common and were observed lunge feeding at the surface on 15 occasions. In addition, this species was documented surface lunge feeding on Pacific Herring (Clupea pallasi) and Pacific Sand Lance (Ammodytes personatus) on 32 occasions during vessel-based cetacean surveys around Cormorant Island between 2010 and 2014. Although Minke Whales are relatively uncommon in British Columbia, these results indicate that they can regularly be found in specific feeding areas during the summer. [ABSTRACT FROM AUTHOR]

The effects of an environmental stressor (salinity) and an anthropogenic stressor (creosote-derived compounds) on sperm motility, fertilization and early development were investigated in the Pacific herring. In the laboratory, the optimal salinity for sperm motility initiation in response to an egg-derived factor, sperm motility initiating factor (SMIF), was 16-24 parts per thousand (ppt), while the optimal salinity for both fertilization and development was 12-24 ppt. These salinities are approximately one-half that of full-strength seawater. These laboratory data correlated with the optimal salinity for development (16-20 ppt) for embryos deployed at field sites in San Francisco Bay. The effect of individual cations on fertilization was also assessed. Sodium (Na·) inhibited fertilization at concentrations ≤55 or ≥440 mM. Alterations in calcium or magnesium had no effect on fertilization unless omitted from the medium. A similar effect was seen for potassium (K·), but elevated K. in combination with elevated Na· inhibited fertilization to a greater degree than Na· alone.To characterize the mechanism for the effects of altered salinity on sperm motility, changes in intracellular ions in response to SMIF or by manipulation of extracellular ions were investigated. SMIF induced a membrane depolarization that was inhibited by increasing either salinity or the Na' concentration. SMIF, and an activator of protein kinase C. induced an increase in intracellular Ca2+ ((Ca2+]i), which along with motility initiation required the presence of extracellular Ca2+ ((Ca2+]o). An efflux of Na· was observed in response to SMIF, or in the absence of SMIF, in low sodium media. again requiring [ca2+]o. Membrane depolarization. increase in [Ca2+]i, and Na· efflux were inhibited by calcium channel and sodium-calcium exchange inhibitors.Finally, the effects of creosote-derived compounds on development were investigated. Exposed embryos exhibited significant mortality, delay in development, cardiac abnormalities, abnormal movement within the chorion. and edema. Hatching success of exposed embryos was also decreased, and all larvae exhibited severe morphological deforinities (scoliosis, pericardia! and/or yolk-sac edema. Less than optimal salinities (8 and 28 ppt) enhanced the effects of creosote-derived compounds on development.

An eDNA assay for the detection of Pacific herring (Clupea pallasii) in water samples was developed using quantitative PCR (qPCR) technology. Species-specific primers and a minor groove binding (MGB) probe were designed based on the mitochondrial cytochrome b gene sequence. Upon conducting a cross-species test, the target species DNA was not only detected at low concentrations but also with high specificity. The assay was validated using field-collected water samples from aquatic environments known to be inhabited by Pacific herring and tested positive in samples from Pacific herring-inhabited sites. Our in silico, in vitro, and in situ results highlight the sensitivity of our proposed eDNA-based procedure for the detection of C. pallasii DNA, and could provide a non-invasive and non-destructive approach to detect this species and characterize its distribution in the Jinhaeman Bay, Korea. [ABSTRACT FROM AUTHOR]

Abstract The Pacific herring (Clupea pallasii) population in Prince William Sound, Alaska suffered a sudden collapse in 1993 and has failed to recover. No consensus has been reached for the causes of the collapse, but hypotheses span a range of ecological, environmental, and anthropogenic drivers. During the course of investigations into changes in PWS herring and salmon population dynamics and fisheries we discovered that the observed percentage of male herring in spawning biomass estimates appeared to increase since the mid-1980s. Using available data (1983–2015) we analysed sex ratios of herring caught in close proximity to the spring spawn using various gear types. In recent years, the overall sex ratio of Pacific herring in PWS has been skewed towards males (>60%), but only if samples from cast nets are included, which generally catch spawning fish. In contrast, purse seine samples, generally collected days to weeks prior to the spawn, had relatively equal sex ratios. Age also affected the sex ratio, with a higher proportion of older fish being females. Using an age-structured simulation model, we illustrate that overestimating the number of males in the population can lead to biases in estimated model parameters (such as vulnerability at age) and as a result, biases in the inferred age composition of the population, and other derived quantities. After accounting for differences in sampling gears to improve estimated sex ratios, we recommend that future work focus attention on separating spatial and temporal differences in sex ratios of this otherwise much-studied population. [ABSTRACT FROM AUTHOR]

Abstract Age-specific declines in length and weight of Pacific herring occurred in all coastal areas of British Columbia (BC) from approximately 1985 to 2010, followed by a more recent reversal in that trend. Concurrent with declining age-specific size, the number of egg layers deposited on vegetation, as estimated from diver surveys, declined but recently this trend also has reversed. In most areas egg layers declined by half, or more, of pre-decline estimates, from means of about 2–3 layers to about 0.5–1 layers. In general, as egg density declined, no corresponding reductions occurred in other metrics of herring spawning such as the mean length or width of the spawning bed. Correlation analyses indicate that the coherence of these two independently measured trends (declining size-at-age and declining egg density) is highly significant (p ≪ 0.01) in all REGIONs of the BC coast. We briefly examine two of several potential biological explanations for these temporal changes: (1) size-dependent ovary size; (2) size-dependent packing density of spawning fish. Quantitative estimates of herring spawn deposition are integral to herring spawning stock biomass assessments in BC and elsewhere so it is important to understand the factors that affect egg density. Our analyses indicate that changes in herring growth or 'size-at-age', which probably reflect regional warming related to climate change, can subsequently impact parameters of reproduction and spawning behaviour. [ABSTRACT FROM AUTHOR]

The factors affecting herring recruitment are still poorly understood, complicating the prediction of stock dynamics and the choice of operational management strategies. We investigated effects of intrinsic (SSB) and extrinsic factors (physical and biological environments, including competition and predation) on recruitment of the spring and fall spawning components of each of the two herring stocks occurring in the Gulf of the St. Lawrence between 1971 and 2014. Effects of potential explanatory factors on recruit (age 2) abundance were tested using Generalized Additive Models. Model fit was significantly improved by incorporating both physical and biological environmental variability, but effects of herring SSB and predation were not significant. Indices of zooplankton abundance and phenology explained more variance in recruitment than physical indices. Our results emphasize the dominance of bottom‐up processes over SSB in the regulation of herring recruitment. Environmental variability did not seem to act uniformly on the recruitment of either stock or their respective spawning components. A long‐term trend of decreasing recruitment in spring spawners was associated with a long‐term decline in abundance of cold water copepods. In fall spawners, optimal recruitment was dependent on warmer environmental conditions combined with an adequate supply (species composition and phenology) of zooplankton. These results provide the first empirical evidence that spring and fall spawning herring are adapted to contrasting environmental conditions and shed light on the potential mechanisms linking herring recruitment to key zooplankton community characteristics and phenology. Management strategies can be improved by incorporating this new knowledge on environmental drivers of herring recruitment. [ABSTRACT FROM AUTHOR]

Abstract Spawning stock biomass (SSB) and environmental factors, such as water temperature, can affect the size and location of spawning grounds of small pelagic fishes. We examined the effects of SSB, water temperature, and day length on the probability of egg presence of the round herring Etrumeus teres to clarify spatiotemporal variation in its spawning grounds in the Tsushima Warm Current region off the west coast of Japan. Egg presence probability (EPP) was estimated from monthly egg surveys and annual stock assessments from 1997 to 2013. Our results indicated that EPP was positively correlated with sea surface temperature (SST), and increased between 12 and approximately 17 °C, where it became constant, and then decreased when SST exceeded 24 °C. From February to June, locations of the main spawning grounds gradually shifted northeast from the waters off western Kyushu to the Japan Sea as the areas with water temperatures suitable for successful egg development (≥17 °C) expanded. However, few eggs were observed during the season when day length shortened daily, even when SST was suitable. The main spawning grounds expanded more towards northern waters in warmer years than in cooler years. In addition, EPP was positively correlated with SSB, which resulted in an expansion of the spawning grounds into coastal regions in years with high SSB. These results indicate that spawning of the round herring responds to seasonal changes in SST and day length, and interannual fluctuations in SST and SSB in the Tsushima Warm Current region. Highlights • Spatiotemporal variations of spawning grounds of round herring were presented. • Location of the spawning ground shifted with increase of water temperature. • Spawning grounds expanded more towards northern waters in warmer years. • Size of the spawning grounds expanded with the increase in spawning stock biomass. [ABSTRACT FROM AUTHOR]

Spatial structures of larval fish in the Strait of Georgia (British Columbia, Canada) were quantified in the springs of 2009 and 2010 to investigate linkages to environmental heterogeneity at multiple scales. By applying a multiscale approach, principal coordinate neighborhood matrices, spatial variability was decomposed into three predefined scale categories: broad scale (>40 km), medium scale (20∼40 km), and fine scale (<20 km). Spatial variations in larval density of the three dominant fish taxa with different early life histories (Pacific herring (Clupea pallasii), Pacific hake (Merluccius productus), and northern smoothtongue (Leuroglossus schmidti)) were mainly structured at broad and medium scales, with scale-dependent associations with environmental descriptors varying interannually and among species. Larval distributions in the central-southern Strait were mainly associated with salinity, temperature, and vertical stability of the top 50 m of the water column on the medium scale. Our results emphasize the critical role of local estuarine circulation, especially at medium spatial scale, in structuring hierarchical spatial distributions of fish larvae in the Strait of Georgia and suggest the role of fundamental differences in life-history traits in influencing the formation and maintenance of larval spatial structures. [ABSTRACT FROM AUTHOR]

Improving fisheries management is a key challenge in addressing the United Nations Sustainable Development Goal 2 (Zero Hunger) and support Goals 1 (No Poverty) and 14 (Life Below Water). However, sustaining the ocean’s living resources has important dimensions beyond food security, such as cultural values, which might be of equal importance in some settings. Fisheries management faces special challenges when there is a mismatch between biological units and management units, e.g., when ecological spatial structures are not reflected in how catch limits are set. This might result in overexploitation and even the loss of sub-stocks. We use a spatially structured ecological-economic model parameterized for a pelagic schooling fish to examine how the benefits of implementing spatially differentiated fisheries management depend on biological parameters. We focus on a subset of socio-ecological variables, i.e., fisheries yield, present value of economic surplus, and loss of spawning sites (which might be linked to loss of cultural values) to demonstrate that, in theory, ideally differentiated spatial management can be implemented without exact information about recruitment behavior. For imperfectly differentiated spatial management, however, knowledge about recruitment behavior becomes key to avoiding economic losses and to sustaining stock structure, especially when there is large spatial heterogeneity in biological parameters. Knowledge about variability in site-specific productivity determines the expectation of achievable sustainable harvest levels. Further research on such ecological issues is therefore warranted, both for ecological as well as economic reasons. [ABSTRACT FROM AUTHOR]

A simulation-estimation approach is used to evaluate the efficacy of stock assessment methods that incorporate various levels of spatial complexity. The evaluated methods estimate historical and future biomass for a situation that roughly mimics Pacific herring Clupea pallasii at Haida Gwaii, British Columbia, Canada. The baseline operating model theorizes ten areas arranged such that there is post-recruitment dispersal among all areas. Simulated data (catches, catch age-composition, estimates of spawning stock biomass and its associated age structure) generated for each area are analyzed using estimation methods that range in complexity from ignoring spatial structure to explicitly modelling ten areas. Estimation methods that matched the operating model in terms of spatial structure performed best for hindcast performance and short-term forecasting, i.e., adding spatial structure to assessments improved estimation performance. Even with similar time trajectories among sub-stocks, accounting for spatial structure when conducting the assessment leads to improved estimates of spawning stock biomass. In contrast, assuming spatial variation in productivity when conducting assessments did not appreciably improve estimation performance, even when productivity actually varied spatially. Estimates of forecast biomass and of spawning stock biomass relative to the unfished level were poorer than estimates of biomass for years with data, i.e., hindcasts. Overall, the results of this study further support efforts to base stock assessments for small pelagic fishes on spatially-structured population dynamics models when there is a reasonable likelihood of identifying the sub-stocks that should form the basis for the assessment. [ABSTRACT FROM AUTHOR]

While the agency of individuals has been identified as a key factor in triggering governance transformations in social-ecological systems, more research attention is needed on how the social position of the actors involved influences these processes of change. Here, we highlight how the unique position of Indigenous women in a recent fishery conflict brought strength to this resource struggle and led to changes in the management of Pacific herring (Clupea pallasii) on the Central Coast of British Columbia, Canada. Through 18 semi-structured interviews with Heiltsuk women and men involved in this fishery conflict, we identified important actions taken by women in the community, which contributed to advancing the preconditions for transformation of the existing governance system. Heiltsuk women took on key leadership roles, increasing social cohesion, facilitating the flow of information, and negotiating among those holding power and conflicting objectives. Viewed through the framework of transformative change in social-ecological systems, women demonstrated strategic agency in challenging colonial governance regimes and catalyzing change. We relate these findings to theoretical understandings of women in environmental justice movements and activism and underscore the importance of Indigenous women as agents of change in their communities and as important actors in fisheries governance transformations. These leadership roles must be recognized and supported to navigate towards natural resource sustainability and social justice, globally, as well as reconciliation for past injustices, nationally. [ABSTRACT FROM AUTHOR]