Spawning habitat characteristics of pacific herring (Clupea pallasii) in Prince William Sound, Alaska

Abstract

Spawning habitats of Pacific herring in Prince William Sound, Alaska were analyzed to determine the importance of habitat features including vegetation type, percent vegetative cover, substrate type, water depth, and shoreline slope in the importance of herring spawning ground selection. Sidescan sonar data were used to compare bottom habitat characteristics of herring spawning areas vs. non-spawn areas. No significant differences in vegetation or substrate type were detected between areas where herring do and do not spawn. Generalized linear models and analysis of variance models were constructed to predict the probability of herring spawn and estimate egg densities given habitat information collected by the Alaska Department of Fish and Game during herring egg deposition surveys. Habitat characteristics explained 31 % of the deviance in spawn presence and absence and 28% of the variability in egg densities. Vegetation type was the most important variable in determining the presence of spawn and vegetative percent cover was the most important variable in determining the intensity of herring spawn. Herring spawned most often on brown and red filamentous algae and red foliose algae. Egg densities increased with increasing percent vegetative cover. Spawning occurred most frequently in the shallow subtidal zone from 0 - 4 m.