THE PLANKTON OF SHELIKOF-STRAIT, ALASKA - STANDING STOCK, PRODUCTION,MESOSCALE VARIABILITY AND THEIR RELEVANCE TO LARVAL FISH SURVIVAL

Physically-mediated variations in production, standing stock and distr ibution of plankton have a significant impact on the growth and surviv al of larval fishes in Shelikof Strait, We integrate descriptions of m echanisms that control the distribution and regional production of pla nktonic organisms with mechanisms that influence survival of early lif e history stages of marine fish, especially the locally abundant walle ye pollock, Theragra chalcogramma. The timing of the spring phytoplank ton bloom is more variable than the regular appearance of pollock larv ae, and is affected by variability in the winter to spring storm seaso n transition, stratification in the Alaska Coastal Current (ACC), and cloudiness. The spring bloom occurs first in the ACC, fuelling local p roduction of copepod nauplii, the main prey item of early larval pollo ck. Shelikof Strait 2ooplankton standing stock is higher in the ACC th an the surrounding Coastal Water (CW) throughout the spring. This is t he result of local production as well as regional production which occ urs upstream of the strait. Mesoscale features associated with the ACC (fronts, meanders, and eddies) determine the distribution of plankton through physical convergence, and reduced dispersion and transport. E vidence for enhancement of planktonic production in these features is lacking, Thus the ACC plays a strong role in determining plankton prod uction, standing stock, and distribution in the Shelikof region. The s trength of the relationship among plankton, planktonic production, lar val pollock growth and survival, and fisheries recruitment is variable . The plankton is only one of several key variables that affect eventu al recruitment to the pollock fishery.