Aquatic Ecosystems and Fisheries: Current Research
Reconstructing Historical Baselines of the Puget Sound Groundfish and Invertebrate Communities
- Tim Essington UW Climate Impacts Group (CIG)
Although human activity has impinged on the Puget Sound ecosystem for years, we have limited understanding about the long-term dynamics of this ecosystem and the roles of human activity therein. This fundamental lack of understanding is now widely acknowledged to be a major impediment to restoring Puget Sound. We seek to collect, organize, and analyze all of the environmental data collected in Puget Sound over the past century, evaluate the cumulative impacts of human activities on this ecosystem, and identify indicator species that can be used to monitor the effectiveness of restoration efforts.
We have compiled all demersal trawl records dating back to 1947, and also analyzed contemporary time series of demersal fish and invertebrate species spanning the last 18 years. The historical record has revealed that, contrary to anecdotal reports, now abundant species such as ratfish appear to have always been dominant members of the community and do not appear to be more abundant now compared to historical times. However, comparison of the historical to contemporary data has revealed that several species, once common, are now virtually absent from Puget Sound. Most of these species are gadoids (Pollock, cod), whose productivity is tightly linked to environmental conditions. We hypothesis that climate shifts have intervened to diminish cod and Pollock productivity and thereby prevent any recovery from fishing.
Moreover, analysis of recent time series data reveals that the demersal community is dynamic, with species exhibiting synchronous shifts in recruitment over the past two decades. Analysis of environmental time series (temperature, salinity) has not identified any relationships between the observed shifts in species composition and potential environmental drivers. However, we note a paucity of the types of data (e.g. detailed larval advection fields, zooplankton abundance and composition) that are most often associated with changes in fish production.
University of Washington School of Aquatic and Fishery Sciences, Washington Dept. of Fish and Wildlife
SeaDoc Society, Wakefield Endowment
For more publications on CIG's research on climate and PNW aquatic ecosystems, please see CIG Publications.