The Pacific herring (Clupea pallasi) resource has supported one of the most important commercial fisheries on Canada's west coast for more than a century. Like many pelagic species, herring productivity has fluctuated throughout this period, especially for the largest population, which spawns in the Strait of Georgia. To provide long term sustainability and cogent management advice it is critical to understand the factors determining herring productivity. Since productivity can be influenced by survival of early life history stages, especially for pelagic species such as herring, we assessed the contribution of bottom-up forcing factors on young of the year (YOY) herring abundance and growth. Herring spawning is closely linked to the annual plankton production cycle and the match (or mismatch) between egg deposition and the initiation of the spring plankton bloom has a substantial impact on survival and production of YOY herring. Enhanced long-term monitoring of the production cycle could provide a better understanding and ultimately a prediction of Pacific herring production within the Strait of Georgia. Crown Copyright (c) 2013 Published by Elsevier Ltd. All rights reserved.

There have been recent changes in the Caspian Sea ecosystem, such as those due to changes in sea level or those caused by the invasive ctenophore, Mnemiopsis leidyi. It is believed that these changes had significant impacts on the absolute and relative abundance of the commercially important anchovy kilka (Clupeonella engrauliformis) and common kilka (C. cultriventris caspia) leading to decline in the former and increase in the latter species in the Iranian waters. Consequently, more rigorous management is required. The mixed-species yield-per-recruit was applied to the Iranian conical lift-net. This study showed that the pooled fishing mortality at F(40%) was 0.70 yr(-1) which is higher than fishing mortality of main species of anchovy kilka, but lower than the pooled fishing mortality at F(0.1) (0.75 yr(-1)). The ABC under the best information available, at pooled species reference points for two species of anchovy and common kilkas, was estimated to be 8260mt. An analogous goal in a multispecies situation would be fishing at a fishing level, denoted F(ws), such that the fishing rate for the weakest stock (in this case; anchovy kilka) does not exceed its F(40)% rate. Under this harvest strategy at F(40%) for anchovy kilka, it is suggested that the ABC of pooled species of anchovy and common kilkas was estimated 7920mt to be selected in kilka fishery in Iranian waters.

We review age-specific growth, recruitment, and population diversity of herring (Clupea pallasi) in the North Pacific. Eastern Pacific herring are smaller, grow slower, and reach a lower asymptotic weight (W∞) than western Pacific herring. In the eastern Pacific, there are latitudinal differences in size but this variation is slight compared to east–west differences. The east–west growth differences match geographic patterns of genetic variation between eastern and western Pacific herring described in earlier reports. Both the genetic studies and the growth variation show that virtually all western Pacific herring populations, including those in the Bering Sea, cluster in one group, and all eastern Pacific herring, from the Gulf of Alaska to California, cluster in a second group. Population diversity, estimated as the number of separate populations per degree of latitude, is highest in the mid-ranges (latitudes) of herring distribution but the available supporting data are limited. Recruitment variation, examined by comparing the coefficient of recruitment variation for nine eastern Pacific herring populations, was highest in the Gulf of Alaska and lowest in southern populations. We suggest that the broad geographic differences in herring populations are adaptive, evolving in response to local prey resources, competitive and climate regimes. If so, examination of these differences can provide insight about potential effects of future climate change.

This paper examines the changes in the population biology and biomass of common kilka (Clupeonella cultriventris caspia) in the Iranian waters of the Caspian Sea from 1995-2004. For most years during this 10-year period, we estimated the age structure of the catch, length-weight relationship, von Bertalanffy growth parameters, condition factor, sex ratios, maturity stages determined from ovarian analysis, natural and fishing mortality, age at first capture and biomass. Growth parameters were estimated as L infinity=132mm, K=0.259/yr, t(0)=-1.285/yr. The instantaneous coefficient of natural mortality was estimated as 0.506/yr and the instantaneous coefficient of fishing mortality varied during the 10-year period between 0.125/yr to 1.487/yr. Biomass of the common kilka increased from about 16,000mt in 1995 to more than 41,000mt in year of 2002. This increase in common kilka was simultaneous with a sharp decline in anchovy kilka, changes in zooplankton abundance and composition, and especially increase in zooplankton species used by common kilka. We concluded that at the present time, the stock of common kilka is being over-fished.

Future management of eulachon fisheries (Thaleichthys pacificus) in the Fraser River requires a management plan based on objective criteria. Ideally such criteria would be based on biological indicators and for each indicator there may be an explicit "reference" point that triggers a management decision. Usually reference points are determined from an understanding of population dynamics of a species. The main indicator for Fraser River eulachon is the spawning stock biomass (SSB) estimated annually since 1995 from egg and larval surveys. With such a short time series, we could not define explicit reference points based on population dynamic models. Instead, for the SSB and other indicators, we defined several "response" points. These response points are based on our judgment about the reliability of indicators that we think are precautionary and biologically realistic. We present these response points in the context of a "traffic light" scenario where, for example, an SSB of less than 150 t, for 2 consecutive years would represent a red light and fishing would not occur. A second indicator is an offshore eulachon biomass index estimated during annual shrimp trawl surveys in May. A biomass estimate of less than 1,000 t in offshore waters is a response point (yellow light) for concern about Fraser River eulachon fisheries. Another indicator is the assessment of the spawning run and catch data from the Columbia River fishery which occurs about 4 months prior to the fishery in the Fraser. A poor run or low catch in the Columbia may anticipate low Fraser River catches and could be a response point (yellow light) for the Fraser River. The last indicator is test-fishery data collected since 1995; but the reliability of these data remains uncertain-comparison of test-fishery catches with the SSB is promising but not convincing. However, these data provide a reassurance about run strength that may be useful for in-season management decisions. The paper concludes with a discussion of how to reconcile conflicting indicators in the context of the traffic light scenario.

We determined the scale of aggregative response of Harlequin Ducks (Histrionicus histrionicus) to seasonally and locally superabundant prey at Pacific herring (Clupea pallasi) spawning sites in the northern Strait of Georgia, British Columbia, in 1995-2002. Aggregations of 3400-5500 birds gathered at a small number of sites along the same 8-km stretch of shoreline each year that spawn was available there. Aggregations occurred in only a small fraction of the habitat area where spawn was available. Duration of stay at spawning sites averaged 2-3 weeks and many birds returned to their wintering grounds afterwards. Birds moving to spawning sites represented 55-87% of the total wintering population. The proportion of local wintering populations that moved to spawning sites was negatively related to the distance they had to travel, and few birds travelled farther than 80 km. The decline in proportions moving with increasing distance suggests that more distant individuals may be constrained by a lack of information or that there are tradeoffs between the benefits of exploiting spawn and the costs of movement. This raises a conservation concern because the temporal and geographic range of herring spawning in British Columbia is contracting and some wintering waterbird populations may be losing access to this important late-winter food.

* This series documents the scientific basis for the evaluation of fisheries resources in Canada. As such, it addresses the issues of the day in the time frames required and the documents it contains are not intended as definitive statements on the subjects addressed but rather as progress reports on ongoing investigations. * La présente série documente les bases scientifiques des évaluations des ressources halieutiques du Canada. Elle traite des problèmes courants selon les échéanciers dictés. Les documents qu’elle contient ne doivent pas être considérés comme des énoncés définitifs sur les sujets traités, mais plutôt comme des rapports d’étape sur les études en cours.

More than 570 000 Pacific herring (Clupea pallasi) were tagged with external anchor tags during 429 tag release sessions between 1979 and 1992. Individually numbered tags were released in quantities of 1000–2000 at a time and recovered from commercial fisheries. Often several tags were recovered at the same time and place, and some recoveries occurred as "matches", where two or more tags from a single release session were recovered together. We tested the hypothesis that the frequency of matching tag recoveries occurred by chance through random mixing of tagged herring before their recapture during fishing operations. The alternative is nonrandom, positive association among tagged individuals that persisted through time and during migrations. We used a statistical method developed to address a similar question in steelhead trout (Oncorhynchus mykiss). In separate tests, we examined tag recovery data from migratory stocks in five major regions of the British Columbia. The results indicate nonrandom association of herring for periods of 6 months to several years and through migrations over considerable distances.

Nearly 1.6 million tagged herring (Clupea pallasi) were released in two separate programs (1936–1967 and 1979–1992) in British Columbia. Several thousand tags were released in each of 955 release sessions. Over 85% of the release sessions had subsequent recoveries. Almost 43 000 tags were recovered over all years. We re-assembled the tagging data into an electronic database, geo-referenced all tag release and recovery data, analysed spatial movements, and estimated straying and fidelity rates. The analyses do not wholly support the conclusions of previous work indicating high homing rates to local coastal areas. Estimates of fidelity, defined as the proportion of tags recovered in the same area as released, varied with the size of the geographic area used in the analyses. Fidelity rates are high for large areas, such as the Strait of Georgia (~10 000 km2), but lower for small geographical areas, such as inlets or bays (~100 km2). High fidelity is not necessarily evidence for "homing." Homing and fidelity are different biological processes and tagging cannot necessarily distinguish between them. Although fidelity rates for small areas are generally low, there are exceptions that may be evidence for the existence of biologically distinct populations in certain areas.

This paper provides an overview of the biology, catch history, and current biomass status of the world's major herring stocks. Herring occur throughout the northern coastal marine areas of the Atlantic and Pacific oceans and parts of the Arctic Ocean. Throughout their entire range, they have been used for food and commerce for millennia. Although several herring stocks have been fished commercially for more than 1,500 years, it is only within the last 100 years that nearly all stocks have been subjected to intense fisheries. During the last century, many stocks "collapsed" but most subsequently "recovered." A few experienced several collapses. Currently, some stocks are thriving but the present state of others is worrisome, This review provides a brief history and review of the present state of each stock provided by the biologists who are familiar with them. In most cases the stocks described in this paper represent aggregations of different biological subpopulations existing within "major stocks." in some instances, especially from multinational fisheries, contributions from different authors were integrated to describe certain stocks. Although our objective was not to explain the causes of variation in abundance, the effect of climatic variation on herring abundance is repeatedly mentioned by various contributors. The effect of climate on Baltic, North Sea, and Norwegian herring has been known for a long time but the effects of climate are reinforced in this report for other stocks. We also see that some changes appear to be synchronous among stocks within the same general areas of the Atlantic and Pacific. In particular, we see a pattern of increases in herring stocks in the southwest Atlantic (Georges Bank, Maine) but a decrease in some in the northwest Atlantic (Newfoundland). Another clear observation is that while there are many biological differences among herring stocks, almost all are subject to substantial fluctuations in abundance and the most severe declines are preceded or accompanied by intense fishing. The temporal duration of periods of crash and recovery vary, but in general it is about a decade or longer. This would be expected given the life span of herring, which ranges from about 6 or 7 years in extreme southern populations to 20 years or more in northern populations. In most instances, when fishing decreases the stocks "recover" but this has not occurred in the Hokkaido-Sakhalin stock, which was once one of the world's largest, with nearly 1 million landed annually. There is no clear explanation for the failure of this stock to recover after all fishing has stopped, unless the population has been depleted beyond a point of no return. Although there is still hope that this stock may recover some day, after a decline of 50 years perhaps a "recovery" is not possible. There still are herring in the area but it is not clear if the small local stocks that still occupy those areas are part of the same biological entity that was once the great migratory Hokkaido-Sakhalin herring stock. The virtual disappearance of the Hokkaido-Sakhalin herring, when considered relative to the last century of herring fisheries in other areas of the world, indicates that herring stocks are remarkably resilient, but perhaps not indestructible.

We compared courtship behaviour of male threespine sticklebacks (Gasterosteus aculeatus) from an 'old' hybrid zone (OldHZ) and 'new' hybrid zones (NewHZ) in southwest British Columbia. High frequencies of phenotypically-intermediate forms occurred in each HZ, between the low-plated freshwater (FW) and high-plated marine (MAR) forms. The OldHZ was formed early in the present post-glacial period and probably has existed for thousands of years. The 'new' HZ (NewHZ) is a system of drainage ditches built in the late nineteenth century. In the laboratory, we quantified and compared courtship behaviour (zigzags, bites, creeping through, fanning) of males from each HZ. We compared these results with those from a previous study that quantified courtship of FW and MAR males. In general, courtship of male from the NewHZ was intermediate between the FW and MAR forms, but zigzag courtship of males from the OldHZ was the significantly less vigorous. In general, other courtship behaviour (biting, fanning, gluing, crawling through and the first response) of hybrid zones males was intermediate between FW and MAR males. Within each HZ, courtship differences were not related to phenotype (lateral plates) or size of males or females. The reduced zigzag courtship of OldHZ males is consistent with the hypothesis that change in courtship behaviour of hybrid phenotypes is evidence of the development of premating isolating mechanisms between the FW and MAR forms. There is no evidence, however, of any form of hybrid inviability although we did suspect that we had less success getting OldHZ males to build nests in our laboratory tanks. Without firm evidence of some form of hybrid inviability, the conclusion that male courtship could serve as an isolating mechanism remains speculative.

In 1977 an exceptionally strong year class of herring (Clupea pallasii) developed in many parts of British Columbia (B.C.) and Alaska. Within B.C. the strong 1977 year class occurred among geographically separated stocks, with different spawning times. In B.C. the number of eggs deposited in 1977 was approximately normal. The 1977 year class recruited to the B.C. herring fishery in 1980 as age 3 and dominated catches for more than 5 years. From analysis of sample data, we determined that the age-specific size of juveniles from the 1977 year class was normal but in later years size at age decreased relative to that of year classes from other years. We confirmed this through analyses of early growth from archival collections of herring scales. Scale growth of the 1977 year class during ages I and 2 was normal, indicating robust somatic growth of 1977-year-class juveniles in 1978 and 1979. Postrecruit growth, however, was below normal. The changes in age-specific difference in growth correspond approximately to different habitats used by pre- and postrecruit herring. In general, prerecruits occupy shallow, nearshore waters for the first 2 years of life. Robust juvenile growth within a strong year class is evidence of an abundant food supply for juveniles in 1978 and 1979. In contrast, the relative growth rates of 1977-year-class adults in offshore waters were much slower in postrecruits relative to that of preceding years, perhaps reflecting density-dependent limitations to growth. We speculate that a climate-based enhancement of juvenile food supply, particularly copepods, could have led to increased juvenile growth and decreased predation on young herring stages. This is consistent with the observation that the 1977 year class was strong in several other species.

Due to the apparent decline in size of a number of populations, eulachon, Thaleichthys pacificus, have recently become the focus of a conservation movement in the northeast Pacific. Little is known of the marine life-history phase of this anadromous fish, and although it has been suggested that eulachon spawning in different rivers may form distinct populations, nothing is known of their population structure. Molecular genetic data were used to investigate population structure and possible management schemes. Mitochondrial DNA genotypes, determined through restriction fragment length polymorphisms (RFLP) analysis, were resolved in fish from several rivers throughout the geographical range of eulachon. Our data support the idea that extant eulachon populations result from postglacial dispersal from a single Wisconsinan glacial refuge. Further, while three of the 37 haplotypes recovered account for approximately 79% of the samples, many private haplotypes were observed, suggesting possible regional population structure. While a great deal of genetic variation was observed (37 haplotypes in 315 samples), an AMOVA showed that > 97% of the total variation was detected within populations. As yet, it is unclear whether genetically distinct populations of eulachon exist, or if these fish may be treated as one or a few large populations. Results were tested against predictions made from hypotheses concerning the origin and persistence of subdivided populations in marine species, and seem to be more consistent with the Member-Vagrant hypothesis than isolation by distance. Eulachon present an interesting situation that illustrates the difficulties involved in defining management units in organisms with high levels of gene flow.

Pacific herring (Clupea pallasi) life history is closely associated with the continental shelf and adjacent coastal areas. In general, throughout the Northern Hemisphere, areas with large herring populations have broad continental shelves, and areas with small populations have small or narrow shelves. Eased on our own observations and data, we suggest that adult Pacific herring distribution is confined mainly to water with depths not exceeding 200 m. Within this depth range, herring aggregations often associate closely with the bottom in daylight hours, rising in darker hours. We do not often see acoustic targets resembling herring or catch herring in deeper water. We observe that summer distributions, when herring feed extensively, seem to be more diffuse than winter so the available areas for summer feeding may be part of the fixed carrying capacity for herring in all areas. This paper presents maximal estimated stock sizes for 14 different Pacific and Atlantic herring stocks, or production areas, and compares this with estimates of the associated shelf area. As an approximation, the density-independent maximal biomass of each stock is defined mainly by the availability of shelf area. We suggest this is a rough approximation of summer feeding habitat, and the maximal average density seems to be about 10 g/m(2). Pacific herring life history, however, includes at least five different stages (egg, larval, juvenile, adult summer habitat, adult winter habitat) and each stage might use different habitats. The availability of other habitats may impose limitations to population size that supersede continental shelf area as a limiting habitat. Also, other density-independent factors (i.e., annual variation in oceanographic climate) and density-dependent factors (predation, food availability) often operate within the constraints imposed by habitat limitation.

Pacific herring Clupea pallasi spawn in shallow and intertidal areas. Larval distributions and abundance of three major and several minor stocks were examined to determine if larvae mix among different spawning locations. The surveys were short, intensive, and occurred mainly within the first 30 days of larval life. Each major stock had a discrete larval distribution with continuous larval distributions within stock boundaries. Some overlap of distributions occurred among smaller stocks. Most larvae were found in inshore waters but there were no obvious oceanographic factors, such as fronts or eddies, to explain all the distributions. Estuarine circulation in inlets could promote larval retention in some areas. The results support the present geographic definitions for local herring stocks. The results are generally consistent with the concept of discrete larval distribution, including retention areas, as the basis for herring Stock Structure.