Herring gather to spawn in large numbers. This provides an opportunity to get information on the biomass of the spawning stock and age composition. This information is then fed into the age-structure-analysis model to estimate the return for the next year.
Aerial surveys are used to measure the miles of spawn, estimate biomass, and map congregations of birds and mammals. Information is recorded on an electronic tablet and photographs taken for confirmation of the distribution of spawn. Fish are collected using a seine or cast nets. The fish are frozen and later analyzed to determine age, weight, length, and sexual maturity. Fish are also provided to the herring disease and maturity projects. The length-weight information used by the acoustic survey project.
This project provides the data required to estimate the herring population in Prince William Sound. The observations are provided to all of the other projects for use in their analysis. It is only by collecting the information included in this project that we can determine the status of herring recovery.