Abstract: We used stable nitrogen isotopes to describe the pelagic food-web structure of three coastal Baltic Sea areas, each of which was sampled twice. Two of the areas were influenced by 15N-rich nutrient discharges from a sewage treatment plant. Analyses were made of particulate organic matter (<35 μm, mainly phytoplankton), zooplankton, mysids (Mysis mixta and M. relicta), sprat (Sprattus sprattus), smelt (Osmerus eperlanus), four size classes of herring (Clupea harengus), and pikeperch (Stizostedion lucioperca). Discharges from the sewage treatment plant significantly increased δ15N values in the whole food web, from phytoplankton to piscivorous fish. Based on nitrogen isotopic compositions, consistent trophic food-web structures were observed on both occasions and in all three areas. The results indicate that zooplankton and mysids may have more complex diets than assumed before. Apparent trophic fractionation, i.e., differences in δ15N between a consumer and its assumed food, averaged 2.4‰ with a standard e...

Abstract: The escape behaviour of solitary herring (Clupea harengus L.) startled by a sound stimulus was observed by means of high-speed video-filming. The results were compared with data from a previous study on the escape behaviour of schooling herring. Escape responses were divided into “away responses” and “towards responses” according to the orientation of the C-bend of the body relative to the stimulus. The proportion of away responses was smaller for solitary than for schooling herring. In solitary herring, the subsequent escape trajectories of fish making initial away responses showed a bimodal pattern of distribution, with modes at 130 and 180° from the stimulus. Trajectories following towards responses, however, were mainly within the semicircle directed at the stimulus, and their pattern of distribution differed from that of away responses. This result contrasts with observations on schooling herring, whose trajectories following both initial away and towards responses are directed away from the stimulus. In addition, we measured the response latency, defined as the interval of time between stimulus presentation and the first detectable movement of the fish. Solitary herring showed a higher proportion of short-latency responses (latency <50 ms) than schooling herring. Different behaviours appear to be exhibited by herring depending on whether they are solitary or within a school. We hypothesize that schooling may raise the threshold for initiation of fast escape responses, giving longer latencies and slower responses which are more appropriate in their directionality and reduce the possibility of collisions with neighbours. In addition, we suggest that schooling behaviour enhances the directionality and co-ordination of the escape response of the whole school, possibly increasing the probability of surviving a predator attack.

Abstract: During 1992–93, an extensive collection program of seal stomachs was conducted as a part of the Multi-Species Research program of the Marine Research Institute in Iceland which commenced in 1991. The aim of the seal part of the program was to investigate their food and feeding habits and role as top-predators. In total 1 059 stomachs from grey seals (Halichoerus grypus) (737 had food remains), 799 stomachs from common seals (Phoca vitulina) (493 had food remains), 62 stomachs from hooded seals (Cystophora cristata) (47 had food remains) and 72 stomachs from harp seals (Phoca groenlandica) (39 had food-remains) were obtained. The main food species of grey seals in Icelandic waters ordered in percentage by weight, were cod (Gadus morhua), sand eels (Ammoditdae), catfish (Anarhichas lupus), saithe (Pollachius virens) and lumpsucker (Cyclopterus lumpus). Seasonal and geographic variation observed during the period January to September, showed sand eel was the dominant food of grey seals off the south-coast of Iceland, but cod, catfish, saithe and lumpsucker in other areas. During breeding, October to December, sand eel still dominated in grey seals from the south coast of Iceland, while saithe, catfish and lumpsuckers did not occur in the diet in the same amount in the west-northwest-northeast-east coastal area, where bull-rout (Myoxocephalus scorpius) was the main prey. The main food species of common seals in Icelandic waters, ordered in percentage by weight, were cod, redfish (Sebastes sp.), sand eels, saithe, herring (Clupea harengus), catfish and capelin (Mallotus villosus). The most pronounced geographic difference in feeding was between common seals from the south coast and seals from the other coastal areas. Sand eel was the main prey item in the south, but cod in the other areas. There seemed to be no seasonal variation in feeding on cod, however, capelin and herring were more important in the diet in autumn/winter. Sand eel, on the other hand, was more important in the food in most coastal areas during spring/summer, than in autumn/winter. The main food items of hooded seals were, redfish and cod, while harp seals took sand eels, herring, bull-rout and cod. The cod eaten by grey seals were mainly of the 2–5 year-olds, the common seals fed mostly on 0–3 year-olds, hooded seals on 3–5 year-olds, and harp seals on 0–2 year-olds.

Abstract: Newly hatched autumn-spawned herring larvae Clupeu lzurengus were released in two 2500-m' outdoor mesocosms and reared over a 2-month period. Hydrographic conditions were similar in the two mesocosms, but the average plankton density was initially more than 10 times higher in mesocosm B compared to mesocosm A (>1 1 Half-way through the experiment the feeding conditions reversed with three times higher average densities in mesocosm A than in mesocosm B (>3 1 ~ ' v. - 1 1 ~ '). Herring larvae were sampled with a 0.3-m2 two-chambered net twice weekly, and survivors were harvested by draining the mesocosms at the end of the experiment. Otolith growth trajectories of individual larvae were determined by relating radial otolith size with number of increments from the outer edge of the otolith (days before capture). The increment widths during the first 3 weeks after hatching, including the first-check size, were generally wider among larvae from mesocosm B (relatively good initial feeding conditions) than among those from mesocosm A (poor initial feeding conditions). The otolith growth pattern also confirmed that the surviving herring in mesocosm A belonged to the upper size range of larvae in the mesocosm after only 2-3 weeks from hatching; no such trend was found in mesocosm B. In both mesocosrns the otolith size-at-age indicated that with the present sampling gear, herring larvae larger than 20--25 mm were underrepresented in the net samples. The information obtained from otolith-size-at-age is compared with other morphometric and biochemical measures of size and condition of larvae

Abstract: .-This study comparedthe hatching season and the actualspawning season of spring-and au­tumn-spawningherring in the north­ernGulfofSt. Lawrenceasdeterminedby otolith characteristicsandmaturitystages. respectively, to measure thecrossover between the two spawningpopulations. Thegrowthcharacteristicsoftwo cohorts that showed significantcrossoverwerecontrastedwiththoseofa cohort thatdid not. It was concludedthat variable juvenile growth does in­fluence the adoption of the season offirst spawning in these populations.and therefore the progeny of a givenseasonal-spawningpopulationmayre­cruit to a local population that has adifferent reproductive season. It wasalso shown that the twinning ofyear­class strength can be explained by thecrossoverofa largenumberofindividu­als from one seasonal spawning popu­lation to another. The data presentedindicatethatthespawningseasonthatisestablishedatthetimeoffirstmatu­rationis maintainedfor theremainderofadult life. The present study there­fore does notsupporttheconceptofdis­crete sympatric seasonal-spawningpopulations inAtlantic herring.Manuscriptaccepted 7 August 1996.FisheryBulletin 95:126-136(1997).

Abstract: Food type or quality can influence assimilation efficiency (AE). AE (digestibility of dry matter) of two captive adult ringed seals (Phoca hispida; one male, one female) was estimated for five prey types. In trials, each of >8 days duration, the seals were fed redfish (Sebastes spp.), capelin (Mallotus villosus), Arctic cod (Boreogadus saida), Atlantic herring (Clupea harengus) and a mixture of herring and shrimp (Pandalus borealis). Prey were marked so that faecal samples could be matched to individual seals, and AE was estimated by the relative concentration of Mn2+ in food and faeces. AE was high but varied among the prey species (redfish 83%; capelin 87%; Arctic cod 88%; herring 94%; herring/Pandalus mixture 92%). There was a weak, positive relationship between AE and prey lipid content or energy density, but a negative relationship with inorganic content. AE was lower than expected for cape lin with high fat content. AE was not correlated with meal mass, number of fish in a meal, or seal mass. AE did not differ between the two seals.

Abstract: Kaaria¨, J., Rajasilta, M., Kurkilahti, M., and Soikkeli, M. 1997. Spawning bed selection by the Baltic herring (Clupea harengus membras) in the Archipelago of SW Finland. - ICES Journal of Marine Science, 54: 917-923. The spawning bed characteristics of the Baltic herring (Clupea harengus membras L.) were investigated during the spawning season in the Airisto Inlet (Northern Baltic Sea) in SW Finland. Within the area, 46 transects were investigated by scuba diver; 37 transects were randomly selected and 9 were known to be spawning beds. Data on the substratum and vegetation were analysed by principal component analysis and discriminant analysis which revealed 10 parameters describing the spawning beds. Two groups were identified; the first contained most of the known spawning beds as well as those resembling them in many parameter values. These beds were situated near the deepest part of the area and contained broad and rich vegetation zones growing on hard bottoms. Herring eggs were not found on all of these beds, but analysis showed they were all potentially suitable for spawning. The other group consisted of sites with bottoms covered by soft sediments, even near the shore line, with the vegetation zone becoming narrower and poorer in plant species. Only two spawning beds were found in this group.

Abstract: Samples of herring (Clupea harengus) were spice-salted, using the same recipe, as partially gutted (nobbed), completely gutted or fillets. The salt uptake and the development of ripening characteristics were followed during storage at 5 ± 1°C. In fillets the salt uptake was more rapid than that in nobbed or gutted herring. The fillets lost less water than the herring and increased considerably in weight during the salting period. Fillets did not develop the characteristic ripened taste whereas the other two groups had a high intensity of ripened taste. All trial groups sampled during salting had similar texture characteristics. The general proteolytic enzyme activity at pH 8 was low in all groups, although it appeared to be slightly higher in the samples containing part of the intestines. Results indicate that the rate of salt uptake was an important regulator of ripening during spice-salting of herring products.

Abstract: The gonad weight and gonadosomatic index of the male Baltic herring Clupea harengus membras L., were highest at the beginning of the reproductive season (April/May), the values decreasing towards the end of it (July/August) during 1988–1991. The decline could not be explained by fish size but may have been due to fish condition. A high individual variation was typical for both gonad weights and gonadosomatic indices in fish of the same size and maturity stage. The mean density of sperm cells was significantly higher in June (34·9 × 109 ml−1) than in July (19·2 × 109 ml−1, Mann-Whitney U= 17; P<0·05), the variation among the males being high in both groups. Electron microscope analysis showed a severe disruption of the mitochondrial elements in males spawning at 22°C.

Abstract: Forestomach contents from 223 Northeast Atlantic minke whales (Balaenoptera acutorostrata), caught in scientific whaling operations in Norwegian and adjacent waters in 1992–94, were analysed with reference to the feeding behaviour of the species. More than half of the examined forestomachs had single-prey contents. This was particularly evident for krill (Thysanoessa spp.), herring (Clupea harengus) and capelin (Mallotus villosus), while a more frequent occurrence of gadoid species in mixed-prey forestomachs indicated that these were either less common in single-species aggregations or that they may have occasionally been eaten while pursuing the same prey as the minke whales. Within a given area, it appeared that small and large minke whales exploit the same resources, the forestomachs of the larger animals containing larger food quanta than those of smaller ones. Substantial variations in observed weights of forestomach contents suggest that minke whales usually feed during long and well defined feeding bouts separated by non-feeding periods. Krill was, however, usually found in stomachs with little contents suggesting that it may be consumed during shorter and more frequent feeding bouts. That krill was more dispersed in the area than any of the other prey items may have contributed to this. The available data may indicate that the feeding activity of minke whales is low during late night and early morning.

Abstract: Oxygen uptakes, dry weights and energy contents of herring Clupea harengus were measured periodically from the time of egg fertilization to the end of the yolk-sac stage (without added food). Temperature of incubation (3·5–17° C) had little effect on efficiency of conversion of egg reserves to body material.

Abstract: Twenty stations were sampled monthly along a primary marine migration corridor in the northern region of southeastern Alaska to assess the distribution, growth, mortality, and diet of wild and hatchery stocks of juvenile (age -.0) Pacific salmon (Oncorhynchus spp.). Stations were stratified into three different habitats-inshore (Taku Inlet and near Auke Bay), strait (Chatham Strait and Icy Strait), and coastal (Cross Sound and Icy Point)-and sampled aboard the NOAA ship John N. Cobb from May to August 1997. At each station, fish, zooplankton, temperature, and salinity data were collected during daylight with a surface rope trawl, conical nets, bongo nets, and a CTD (conductivity, temperature, and depth profiler). A total of 6,252 fish and squid were captured withthe rope trawl, representing 31 taxa. All five species of juvenile Pacific salmon and steelhead (D. mykiss) were captured and made up 80% of the total catch. Of the 5,000 salmonids caught, over 99% were juveniles, and less than 1% were immatures or adults. Non-salmonid species making up > 1 % of the catch included Pacific herring (Clupea harengus), squid (Gonatidae), capelin (Mallotus villosus), walleye pollock (Theragra chalcogramma), and sablefish (Anoplopoma fimbria). Chum (D. keta) , coho (D. kisutch), pink (D. gorbuscha), sockeye (D. nerka), and chinook (D. tshawytscha) salmon and crested sculpin (Blepsias bilobus) occurred most frequently (~30%) in the trawl catches. Overall catches of juvenile salmon were highest in July and zero in May. Catch rates of coho and sockeye salmon were highest in June, whereas catch rates of chum, pink, and chinook salmon were highest in July. Catch rates of juvenile salmon except chinook salmon were highest in strait habitat and lowest in inshore habitat; chinook salmon catch rates were highest in inshore habitat. Overall catch rates for juvenile salmon along the offshore transect declined with distance offshore: most juveniles were within 25 km of shore, and no juvenile salmon was found beyond 40 km. Mean fork lengths of juvenile salmon in JuneJuly-August were: chum (97-137-162 mm), pink (96-136-156 mm), sockeye (110-146-154 mm), coho (148-207-247 mm), and chinook salmon (143-172-222 mm). Twenty-three juvenile and immature salmon containing internally planted coded-wire tags (CWTs) were recovered; 21 originated in Alaska and two in Oregon (one chinook and one coho salmon). The Oregon chinook salmon is the earliest recorded recovery of a stream-type chinook salmon of the Columbia River stock in Alaska during its first summer at sea. Onboard stomach analysis of potential predators of juvenile salmon did not indicate a high level of salmon predation; however, few predators were present during high levels of juvenile salmon abundance, and fish remains in stomachs were often too far digested to identify. Results from this study and further laboratory analysis of otolith-marked fish will be used to assess competitive interactions between wild and hatchery stocks and stock-specific life history characteristics.

Abstract: The herring catch represents two-thirds of the entire fish catch in the Gulf of Finland. Herring reach maturity at a total length of 12-15 cm by the age of 2-3 years. Spawning takes place in May-June along most of the coast. Mass spawning begins when the water temperature is 8-9 °C; eggs are usually attached to vegetation. Egg development takes 6-15 days. In recent years the growth of herring has been slow. In the catches, the oldest herring have been over 15 years. In the spring trap net catches, the most plentiful age group are the three-year-olds. In the autumn trawl catches, the most abundant age group is one-year-old herring. The stock is presently exploited around the F 0.1 level. Assessing the state of the herring stock in the Gulf of Finland is complicated, because of the spawning and feeding migrations between the Gulf and the Baltic Sea proper.

Abstract: The catch, distribution, and biology were studied in Norwegian spring spawning herring during the spawning season in 1995. Both the spawning time and choice of spawning grounds were influenced by the size and condition of the fish. The stock wintered in Vestfjorden, northem Norway, and spawning grounds were utilized southwards along the coast within a range of 1500 km. The herring arrived the spawning grounds in a decreasing order of length and condition. This was mainly due to size specific swimming speed and not size specific maturation. Delayed maturation with fish length was only found within the recruits, which spawned in a second wave. In addition, the size and condition of the fish in a spawning area increased southwards, and there was a delayed spawning and prolonged spawning period at the northemmost spawning grounds. We suggest that life-history theory explains the observed spawning distribution. Individuals must consider trade off between migration distance, reproductive output, own survival and larval survival based on their body size and condition.

Abstract: Recruitment is generally recognized as a complex ecological process determined by the interrelation ofmany biological and environmental variables and has always been one ofthe most difficult terms to estimate in fisheries science (Russell, 1931). Methods for forecasting fisheries yields with timeseries analyses (Saila et aI., 1980; Mendelssohn, 1980), surplus production models (Schaaf et aI., 1975), and models employed to relate recruitment to egg production (Koslow et aI., 1987), larval abundance (Lett and Kohler, 1976; Lough et aI., 1981; Smith, 1981), or spawning stock size (Sissenwine, 1984) have had limited success. Factors dominating recruitment appear to operate on local scales (Cohen et aI., 1991); changes in physical factors operating through marine food webs are a major force affecting the abundance of fish stocks (Mann, 1993). Clupea harengus, are an important component of the fisheries of the Northwest Atlantic and show great variability in recruitment. Spawning usually begins in the eastern part of the Gulf of Maine (Fig. 1) during August (Graham, 1982; Stevenson et aI., 1989) and over the Nova Scotian shelf (McKenzie, 1964), and occurs as late as November or December (Graham, 1982; Lazzari and Stevenson, 1992). Eggs are deposited on the bottom (Boyar et aI., 1973; Caddy and lIes, 1973; Stevenson and Knowles, 1988) and hatch in one to two weeks depending on temperature. Larvae are transported to estuaries and embayments along the central and western Maine coast (Graham, 1982; Graham and Townsend, 1985) or remain offshore for the winter (Townsend, 1992). The planktonic larval stage lasts until spring when larvae undergo metamorphosis into the juvenile form. Recruitment to the fishery occurs primarily in the following spring (at age 2) when juveniles reach a size appropriate for canning (150200 mm). The recruitment success of herring may be associated with various physical environmental factors, including sea surface temperature (SST) (Sutcliffe et aI., 1977; Cushing, 1982; Anthony and Fogarty, 1985; Murawski, 1993), residual surface currents (Norcross and Shaw, 1984), winds (Corten!; Christensen et aI.2), or atmospheric-pressure gradients (Carruthers, 1938), or a combination of the last two. Theoretical models for predicting variations in juvenile herring production in the Gulf of Maine were developed by using sea surface temperature from the late-larval to early-juvenile period (Anthony and Fogarty, 1985), first quarter (January-March) sunshine CEzzy, 1988), and by using either food supply and spawning distribution when yearclass strength was established during the larval stage or predation for those years when year-elass strength was established in the brit stage (Campbell and Graham, 1991). In addition, several hypotheses concerning wind events or larval dispersal may help us to understand herring recruitment in the GulfofMaine. Ridgway (1975) proposed a conceptual model ofrecruitment variability based on changes in the dispersal of herring larvae by ocean currents from spawning areas to nursery areas. Water column stability and its impact on the availability of food resources for larval fish at some critical life stage also has been proposed to affect recruitment (Lasker, 1975). Periodic winds that produce moderate turbulence may enhance larval survival by increasing the probability of encounter between larvae and their prey (Sundby et aI., 1989; MacKenzie et aI., 1994). The purpose of this study was to associate physical environmental factors with size estimates of age-2 herring of the coastal Atlantic herring stock in order to identify the important environmental factors underlying recruitment variablity and to examine the importance of the wind and dispersal hypotheses

Abstract: Gear selection and sampling gears. Proceedings of the seventh IMR-PINRO Symposium. Murmansk, 23-24 June 1997.

Abstract: The Baltic herring (Clupea harengus membras. L) is one of the most essential commercial fish species in the Baltic Sea. The annual landings of herring have varied from 300,000 to about 480,000 tonnes in recent 20 years. Herring in the Baltic Sea can be treated as a complex of several stoks, each linked to separate spawning grounds. The hydrological, particularly salinity conditions vary from 1–2 on the herring spawning grounds in the Eastern Gulf of Finland to above 10 in the Southwestern Baltic. This shows good adaptation of herring to the low and variable salinity conditions in the Baltic Sea. Despite of that, changes in salinity conditions, depending on occurrence or absence of inflows from the North Sea, seem to have an essential effect on both herring growth and behaviour. The prolonged period of absence of big inflows of saline water into the Baltic Sea can probably even affect of the stock structure of herring. That points at the importance of regular inflows of saline water as the stabilizing factor in the ecosystem of the Baltic Sea.

Abstract: approved: ( AN ABSTRACT OF THE THESIS OF James T. Harvey for the degree of Doctor of Phi1osoph in Oceanography presented on November 10, 1987. Title: Population Dynamics. Annual Food Consumption. Movements, and Dive Behaviors of Harbor Seals. Phoca vitulina richardsi. in Oregon. Signature redacted for privacy. Bruce R. Mate Number of harbor seals, counted on 32 haul-out areas in Oregon, increased by 6 8.8 % per year from 1975 1983. Percent of seals in bays has increased an average 1.8%/year, from 47% in 1975 to 61% in 1983. Along the central Oregon coast, harbor seals were most abundant during January and April. Four environmental factors, height of low tide, amount of rain, wind speed, and wave height, were correlated significantly with number of harbor seals on land. A greater precentage of radio-tagged harbor seals were found on land during summer and spring counts (X = 53.1%), than during autumn and winter ( = 9.2%). There were an estimated 9,023 20,018 harbor seals in Oregon during winter 1985. The results of experiments with captive harbor seals indicated that only 25 34% of some fish species (e.g. Engraulis mordax, Clupea harengus, and Thaleichthys Dacificus) was represented as otoliths in feces, whereas with other species it was 80%. Over 80% of the otoliths were excreted within 24 h of ingestion. Mean reduction in otolith length (X = 27.5%, = 10.3) was not significantly different among fish species. Harbor seals caught in Oregon ( = 214) were an average 126 cm in length and 55.7 kg in mass. Average dive duration for six individuals ranged from 1.0 mm ( = 0.7) to 3.1 mm (SD = 1.8). Maximum dive duration was 11.4 mm. Radio-tagged individuals moved as far as 280 km, but 92% of time were found within 8 km of the release site. Harbor seals fed primarily on fishes of 8 15 cm standard length. Generally they consumed smaller fish in spring and summer and larger fish during fall and winter. Juvenile fishes (e.g. Parophrys vetulus and Citharichthys sordidus) were probably consumed by harbor seals in estuaries, whereas adults were eaten in the ocean. In 1980, 5 species of fishes, Leptocottus armatus (721.4 metric tons), Clupea harengus (451.4 metric tons), Cymatogaster aggregata (440.8 metric tons), Parophrys vetulus (427.8 metric tons), and Glyptocephalus zachirus (332.6 metric tons), comprised 42.5% of a total 5,584.9 metric tons of fish estimated consumed by harbor seals in

Abstract: Viral haemorrhaglc septicaemia vuus (VHSV) was isolated from apparently healthy Atlantlc herrlng Clupea harengus from the English Channel The virus was isolated in bluegill fibroblast (BF-2) cells but not epithelioma papulosum cypnni (EPC) cells, however, the virus was passaged from BF-2 to EPC cells The identlty of the virus was confirmed by an enzyme-llnked ~rnmunosorbent assay and by a reverse transcnptase-polymerase chain reaction (RT-PCR) The virus was classified as a member of genogroup 111 of VHSV which comprises many European freshwater and manne VHSV 150- lates Sequence comparisons of the RT-PCR products showed that the herring isolate was closely related (99 1 % nucleotlde similarity) to a VHSV isolate from Atlantlc cod Gadus morhua both of those isolates were avirulent for rainbow trout Oncorhynchus myklss by bath infection Circumstantial evidence is presented which suggests that VHSV from herring could have been the source of VHS disease in rainbow trout in Denmark

Abstract: A comprehensive survey in the larval distribution area of Norwegian springspawning herring along the Norwegian west coast was carried out annually by the Institute of Marine Research, Bergen in the years 1986-1990. Moreover, two small subareas were sampled repeatedly (usually twice a week) off Sunnmore and at Buagrunnen throughout the hatching period each year. The daily larval production was worked out with the data obtained from the comprehensive survey covering the entire larval distribution area. Data obtained in the subareas had been used to construction the hatching curve so as to get the daily larval production percentage in the hatching period. Then, the annual larval productions were estimated. The· annuallarval production from 1986 to 1990 were 1.7 x10, 3.9 x 10, 35.4 x 10, 72.8 x 10 and 99.1 x 10 individuals.