Physical and biological variables affecting juvenile Pacific herring (Clupea pallasi) in Prince William Sound (PWS) from 1995 to 1998 were investigated as part of a multifaceted study of recruitment, the Sound Ecosystem Assessment (SEA) program. Though more herring larvae were retained in eastern PWS bays, ages‐0 and ‐1 herring used bays throughout PWS as nursery areas. Water transported into PWS from the Gulf of Alaska (GOA) contributed oceanic prey species to neritic habitats. Consequently, variations in local food availability resulted in different diets and growth rates of herring among bays. Summer food availability and possible interspecific competition for food in nursery areas affected the autumn nutritional status and juvenile whole body energy content (WBEC), which differed among bays. The WBEC of age‐0 herring in autumn was related to over‐winter survival. The limited amount of food consumption in winter was not sufficient to meet metabolic needs. The smallest age‐0 fish were most at risk of starvation in winter. Autumn WBEC of herring and winter water temperature were used to model over‐winter mortality of age‐0 herring. Differences in feeding and energetics among nursery areas indicated that habitat quality and age‐0 survival were varied among areas and years. These conditions were measured by temperature, zooplankton abundance, size of juvenile herring, diet energy, energy source (GOA vs. neritic zooplankton), WBEC, and within‐bay competition.

Egg masses of 772 red king crab, Paralithodes camtschatica, were sampled to determine the prevalence, intensity, and patterns of cooccurrence of brood symbionts from 28 Alaskan localities. Carcinonemertes regicides and three other undescribed nemertean egg predators were recovered from many localities, as were an undescribed turbellarian and an amphipod, Ischyrocerus sp. A widespread outbreak of nemerteans occurred in the 1983–84 and 1984–85 red king crab brooding seasons. At some locations, nearly all of the eggs were consumed in the 1983–84 brood season. Feeding of C. regicides on eggs was documented in vitro and these worms caused substantial egg mortality at many locations. The amphipod was also an egg predator and may have had a significant impact at three locations. The turbellarian did not kill eggs. From the seasonal pattern of C. regicides infestation at Kachemak Bay, we postulate an abbreviated life cycle and autoinfection for C. regicides. Such life history features may have contributed to the peak intensities observed late in the 1983–84 and 1984–85 brooding seasons. At some localities, heavy brood mortality may reduce or eliminate recruitment of some year classes to the fishery.

No abstract

During the winter of 1996-1997, somatic energy content and diets of age-0 Pacific herring Clupea pallasi from Prince William Sound, Alaska, were examined. From October to March, the standard length of age-0 recruits continued to increase, indicating either growth or mortality of smaller fish. The whole-body energy content averaged 4.4 kJ/g wet weight for fish captured in October and increased to 5.0 kJ/g wet weight in November. Thereafter, somatic energy continually declined, reaching 3.9 kJ/g wet weight in March. The December-March decline in nutritional status of the recruits verified that the energy derived from feeding was not enough to meet metabolic needs. The energy density of taxa found in the diets remained steady through the winter and increased in March. Total zooplankton biomass, however, decreased as the mean water temperature decreased. Estimated assimilation rates were lower for smaller fish than larger fish and decreased as winter progressed. We concluded that juvenile herring rely on energy stores to overwinter and that smaller fish are more likely to be affected by starvation. Also, the duration of overwinter starvation may be related more to photoperiod than to mean water temperature.

During the early spring four groups of sub-adult Pleuronectes asper were fasted for either 0, 2, 4 or 6 weeks at the beginning of a 12-week experiment, then fed to satiation to examine their ability to compensate with faster growth after food deprivation. All fish increased their stored energy reserves markedly and at the end of the experiment all four groups had similar body energy content (J g-I), length gains and dry weight to wet weight ratios. The groups of yellowfin sole fed continuously or fasted for 2 weeks gained the most weight, 25 and 24% respectively. Fishes fasted either 4 or 6 weeks exhibited significantly lower weight gains of 16 and 15% respectively over the 12-week experiment. Because of this disparity in weight gain the total body energy content of the continuously fed fish and those fasted for only 2 weeks increased by approximately 60 vs 46%) or 35% for sole fasted for 4 or 6 weeks.The experiment showed P. asper had a limited capacity for compensatory growth. When food was scarce yellowfin sole allocated energy preferentially to growth in length instead of weight. These findings may account for some of the interannual differences in mean length and weight at age for yellowfin sole from the Bering Sea where variations in extent and duration of ice cover and the boreal bottom water delimit the growing season.