• Temperature and food effects on larval Pacific herring (Clupea pallasi) in Prince William Sound, Alaska

      Thornton, Sarah Jane (2003-08)
      The effects of food availability and water temperature on larval Pacific herring growth rates and survival were studied using a coupled biophysical model for 1993 through 1997. The herring growth model included feeding gains, metabolic costs, mortality losses and vertical migration of the herring larvae. In years when springtime oceanographic processes resulted in a high concentration of zooplankton, food availability did not limit larval herring growth rates; water temperature determined survival. However, in other years, food availability did limit survival, either due to insufficient food concentrations or to inaccessibility of the food. Vertical migration occasionally was restricted by strong water column stratification, which prevented the larvae from reaching food concentrations sufficient for growth. Thus the amount of food, the temperature, and the vertical distribution of the food and the larvae were found to affect growth. The study of vertical properties of factors affecting larval fish must be included in larval fish research.