With the current trends in climate and fisheries, well-designed mitigative strategies for conserving fish stocks may become increasingly necessary. The poor post-release survival of hatchery-reared Pacific salmon indicates that salmon enhancement programs require assessment. The objective of this study was to determine the relative roles that genotype and rearing environment play in the phenotypic expression of young salmon, including their survival, growth, physiology, swimming endurance, predator avoidance and migratory behaviour. Wild- and hatchery-born coho salmon adults (Oncorhynchus kisutch) returning to the Chehalis River in British Columbia, Canada, were crossed to create pure hatchery, pure wild, and hybrid offspring. A proportion of the progeny from each cross was reared in a traditional hatchery environment, whereas the remaining fry were reared naturally in a contained side channel. The resulting phenotypic differences between replicates, between rearing environments, and between cross types were compared. While there were few phenotypic differences noted between genetic groups reared in the same habitat, rearing environment played a significant role in smolt size, survival, swimming endurance, predator avoidance and migratory behaviour. The lack of any observed genetic differences between wild- and hatchery-born salmon may be due to the long-term mixing of these genotypes from hatchery introgression into wild populations, or conversely, due to strong selection in nature—capable of maintaining highly fit genotypes whether or not fish have experienced part of their life history under cultured conditions.

The abundance and distribution of overwintering Calanus finmarchicus in the NE Norwegian Sea and shelf waters off North Norway was studied during January for 2000–02. Depth integrated distribution of C. finmarchicus CV showed aggregations with high abundances in the Lofoten Basin and southwest of Tromsøflaket for all three years. The exact location of the aggregation areas and the maximum abundances did, however, vary between the years. The concentrations southwest of Tromsøflaket were almost twofold higher in 2000 at 150 000 ind. m−2 compared to 70 000 and 90 000 ind. m−2 in 2001 and 2002, respectively. Vertical distribution of the animals was similar for the three years, with most of the CVs of the population residing in the depth interval between 700 and 1200 m. Peak abundances of 350 ind. m−3 were found at 850–1000 m west of Tromsøflaket in 2000, whereas in 2001 the maximum abundances were located in the Lofoten Basin at 700–900 m, in the order of 150 ind. m−3. In 2002, the highest concentration of animals was found west of Vesterålen between 1100 and 1200 m, with a concentration of 385 ind. m−3. The vertical and horizontal distribution of C. finmarchicus CV closely followed the hydrographic structures in the area, with the highest abundances associated with cold (<2°C), less saline (34.85–34.9) water with a density of 27.95–28. The patches of high abundance were located in confined areas along the continental shelf slope and in the Lofoten Basin, indicating that the animals may have been extracted from the highly flushed surface areas in late summer during their ontogenetic descent, and trapped in mesoscale physical features in the deep‐water masses throughout the winter. We argue that deep‐water mesoscale anticyclonic eddies, which are frequently formed along the continental slope and in the Lofoten Basin, may provide favourable retention areas for the overwintering population of C. finmarchicus. Consequently, the impact of ocean climate as well as more regional and local effects on the creation and persistence of these mesoscale features is likely to influence the Calanus abundance and advection paths in the following spring and summer.

The consumption of various prey species, required by the Barents Sea harp seal (Phoca groenlandica) stock in order to cover their energy demands, has been estimated by combining data on the energy density of prey species and on seasonal variations in the energy expenditure and body condition of the seals. Data on diet composition and body condition were collected in the period 1990-1996 by sampling harp seals during different seasons, in various areas of the Barents Sea. All diet composition data were based on reconstructed prey biomass, and adjustments were made for differences in digestibility of crustaceans and fish. The number of seals representing different age and sex groups were calculated for the entire population, and the monthly food requirements were estimated. In 1998, the total Barents Sea harp seal stock was estimated to comprise 2.22 million seals based on a mean production of 301,000 pups. After adjustments for a pup mortality of 30% its total annual food consumption was estimated to be in the range of 3.35-5.05 million tonnes (depending on choice of input parameters). Assuming that there are seasonal changes in basal metabolic rate associated withchanges in body mass, and that the field metabolic rate of the seals corresponded to two times their predicted basal metabolic rate, the annual food consumption of the Barents Sea harp seal stock was estimated. If capelin (Mallolus villosus) was assumed to be abundant, the annual total consumption was estimated to be 3.35 million tonnes, of which 1,223,800 tonnes were crustaceans, 807,800 tonneswere capelin, 605,300 tonnes were polar cod (Boreogadus saida), 212,400 tonnes were herring (Clupea harengus), 100,500 tonnes were cod (Gadus morhua) and 404,200 tonnes were "other fish". A very low capelin stock in the Barents Sea (as it was in the period 1993-1996) led to switches in seal diet composition, with increased consumption of polar cod (from ca. 16%-18 % to ca. 23%-25 % oftotal consumption), other gadoids (dominated by cod, but also including haddock (Melanogrammus aeglefinus) and saithe (Pollachius virens)), herring, and "other fish". Using the same set of assumptions as in the previous estimate, the total consumption would have been 3.47 million tonnes, divided between various prey species as follows (in tonnes): polar cod 876,000, codfish (cod, saithe and haddock) 359,700, "other fish" 618,800, herring 392,500, and crustaceans 1,204,200. Overall, the largest quantities of food were estimated to be consumed in the period June-September.In 1999, the total Barents Sea harp seal stock size was estimated to be 2.18 (95% CI, 1.79 to 2.58) million animals, which would give an annual food consumption in the range of 2,69 - 3.96 million tonnes (based on upper and lower 95% confidence limits and adjusted for a pup mortality rate of 0.3) if capelin is assumed to be abundant.

In order to resolve advection, migration, and in situ population dynamics of zooplankton and capelin larvae in a mesoscale physical setting on the coast of North Norway, an extensive field survey was conducted. This paper reports on the physical conditions in the area and lays the basic environmental understanding for the analysis of vital rates of the biological components studied. We used a towed wing (SCANFISH) equipped with sensors and Objective Analysis for interpolation of hydrographic data into continuous fields. We show the importance of the mixing process along the coast of Norway, and identify the weakening of the signatures of Atlantic Water (AW). We also described the presence of a distinct and isolated water mass that is neither Norwegian Coastal Water (NCW) nor AW. This water mass had intermediate salinity but was significantly colder than NCW and AW. Several distinct non-linear mesoscale eddies were observed during a 12-day period. Anticyclonic eddies had lower salinity, while cyclonic eddies were relatively saline. We also observed meanders further offshore. Elongated eddies with the principle axis parallel to the shelf break developed into relatively larger isotropic eddies. The evolution of the eddy field was examined by cross-correlation between different periods of the survey. The most significant observation is the indication of eddy transport along the shelf. The translation speed was approximately 7 km day−1. We propose that the observed features are formed by baroclinic instabilities of the Norwegian Coastal Current (NCC) and that they play a crucial role as transport agents for biota.

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