Introduction
Pacific herring (Clupea pallasi) are an ecologically critical component of the Prince William Sound (PWS) ecosystem and food web. Fisheries for this forage fish species have also historically been integral to the economic sustenance of local communities in the area. The crash of the herring stock in 1993 and its subsequent failure to recover despite the moratorium on fishing remains an issue of utmost concern.
This has prompted the development of a PWS herring restoration plan initiative by the Exxon Valdez Trust Council (EVOSTC) and an appointed steering committee comprised of scientists, resource managers, fishers, and other community stakeholders.
Central to these restoration efforts is a synthesis of available research results and data to drive the development of a spatially explicit, stage-structured population dynamics model for PWS herring.
Ecosystem Model of PWS Herring will aid in the integration ecological data that has been gathered on herring over the last 2 decades and simulate the processes that have caused the chronic decrease in herring stocks since the 1989 spill. It is being used to test the unresolved hypotheses of why the herring have not recovered to pre-spill densities.
The model and associated data is housed in the EASy geographic information system that developed by System Science Applications specifically for marine applications.
Some of the unique features of this model are:
- The Four Year Cycle in which exceptionally high rates of recruitment are followed by 3 years of low recruitment which was discovered by analyzing the data from Alaska Fish and Game’s Age Structure Analysis (ASA) Model.
- The Unrestricted Cohort Tracking Algorithm, developed by study participant Vince Patrick, which describes the abundance of herring born in a given year as they age and mature from age 0 juveniles that enter coastal nursery grounds to age 9 adults.
- The Nursery Model, developed by Dr. Dale A. Kiefer of USC.