U.S.-GLOBEC: NEP Phase IIIb-CGOA: Habitat effects on feeding, condition, growth and survival of juvenile pink salmon in the northern Gulf of Alaska
L. Haldorson, M. Adkinson [Both at University of Alaska Fairbanks]

Project Summary

Juvenile pink salmon from Prince William Sound (PWS) hatcheries occupy a series of distinct marine habitats during their first summer. All PWS hatchery fish carry thermal otolith marks that allow calculations of growth in the early marine phase and overall cohort survival, thus providing an exceptional opportunity to study the effects of habitat quality. We will use data from four programs that sampled juvenile pink salmon in the northern GOA to estimate feeding intensity, condition, and growth for each hatchery cohort by time and habitat. We will determine where and when favorable habitats occurred, and describe characteristics of habitats where juvenile pink salmon were feeding well, were in good condition, and exhibited fastest growth. There is compelling evidence that mortality of juvenile salmon is reduced in larger individuals; consequently, we will quantify feeding, condition and growth in upper size-based quantiles to determine if characteristics of larger, faster-growing individuals are better indicators of habitat quality than overall means or medians. Our synthesis strategy is a top-down approach, we will use the fish to tell us where and when favorable habitats occurred. Within the GLOBEC program we have an exceptional opportunity to determine what processes were responsible for developing those favorable habitats.

It is clear that climate and oceanographic conditions affect marine ecosystems and salmon production; however, mechanistic understanding of the processes is still lacking. The Optimal Stability Hypothesis (OSH) suggests that, in the northern GOA, increased water column stability during summer enhances primary production and zooplankton abundance; leading to enhanced feeding, growth and survival of juvenile salmon. We will examine water column stability, depth distribution of chlorophyll, light availability at depth, zooplankton abundance and salmon response variables (feeding, condition and growth) to determine if there are significant relationships among them, and if those relationships are consistent with the OSH.

Intellectual Merit - The northeast Pacific Ocean has become a focus of oceanographic interest since observations that decadal-scale fluctuations in salmon abundance are linked to basinwide changes in meteorological forcing and oceanographic conditions. These regime shifts indicate that climate changes are quickly expressed in biological productivity, although the mechanisms that alter ecosystem structure and function are not well documented. Pink salmon are particularly suited to serve as indicators of marine conditions, as they are abundant and have a short, two-year life cycle with non-overlapping generations. The synthesis research we propose will demonstrate how conditions in nearshore marine habitats affect juvenile pink salmon, and thus will contribute substantially to understanding of how marine ecosystems respond to climate shifts.

Broader Impacts - The synthesis research we propose will have broad applications to research infrastructure in Alaska, and to management of important resources. One important outcome will be development of a comprehensive database for pink salmon juveniles, compiled from four projects. The database will be an asset to other synthesis projects and to future research. Education and research are closely linked at the U. of Alaska Fisheries Division, our research plan includes support for a Ph.D. student and for a post-doctoral fellow. We will collaborate with scientists at the Alaska Dept. of Fish and Game, who would like to use early marine survival estimates to improve forecasting, and who will be providing a data set for the database. Also, both P.I.s in this project have been working closely with an alliance of stakeholders in the PWS salmon fishery, and will continue to do so. We will use a website developed by that group to communicate results of our synthesis research to the broader resource-dependent community of PWS and the northern GOA.

NSF Award Summary

None available.

This page was last updated on March 14, 2007.

Maintained by:
Hal Batchelder
College of Oceanic and Atmospheric Sciences
Oregon State University
Corvallis, OR 97331-5503
phone: 541-737-4500; FAX 541-737-2064