Develop Environmentally Explicit Population-Dynamics Models for Coho Salmon
Current Status of Accomplishment or Milestone: An ongoing collaboration has been formed with Professor Marc Mangel, Center for Stock Assessment Research (CSTAR), University of California at Santa Cruz.
An environmentally explicit model of individual growth has been developed and parameterized from published data sources. Growth information has been retrieved from the Coded-Wire Tag Database (http://www.rmis.org), and this information has been used to evaluate predictions from the growth model. This work has been submitted for publication; referees comments have been received; and the manuscript is currently being revised
Additional modeling in which the environmentally explicit growth model is used to describe how ocean conditions influence the age at maturity has nearly been completed. A draft manuscript describing this work is nearly complete, but cannot be finalized until the growth model is accepted for publication.
Background: Population-dynamics models provide methods both to synthesize multiple types of data and to evaluate the mechanisms by which environmental variation influences the production of marine resources. It is recognized that variation in ocean conditions influences the survival of coho salmon, but observational data (e.g., numbers of individuals returning to spawn) can often be explained equally well by environmental effects on survival or environmental effects on maturation. In reality, environmental conditions probably influence both survival and maturation. Since both of these process are size-dependent, an environmentally explicit growth model seems appropriate. To our knowledge, no such model exists for coho salmon. We have developed an environmentally explicit growth model by reparameterizing the well know von Bertalanffy function. This growth model can easily be extended to consider other salmonids and marine fishes in general.
Purpose of Activity/Goal of Project: Evaluate mechanisms by which environmental variation influences the production of coho salmon, and thereby improve predictions about future productivity of these fish. Integrate multiple data sources into the predictive tools.
Description of Accomplishment and Significant Results: A post-doctoral fellow was successfully co-sponsored through a collaboration between CSTAR and PFEL. The post-doc has subsequently been hired to continue work at PFEL through the Joint Institute for Marine and Atmospheric Research.
An environmentally explicit model of individual growth has been developed and compared to observed data describing coho growth at sea. This work was submitted to the Journal of Fish Biology for publication. Referees' comments have been received and the manuscript is currently being revised. Our results illustrate how fish behavior interacts with environmental conditions to determine growth conditions in the sea.
The growth model has been used to describe how ocean conditions influence the age at which coho salmon mature. A draft manuscript describing this work is almost complete.
Significance of Accomplishment (e.g., to the Center, to Management, and to NMFS Strategic plan Goals): Co-sponsoring post-docs is an important method of providing new scientists with quantitative skills that are of use to NOAA Fisheries. Ultimately, bringing these individuals into the agency will improve our ability to provide stakeholders and decision makers with useful scientific advice.
Our modeling work is significant because it provides a method of evaluating the mechanism by which conditions in the ocean influence both the survival and maturation of coho salmon. Ultimately, mechanistic models like ours may increase our ability to predict how salmon production will be influenced by conditions in the ocean.
Our growth model can also be used to describe how conditions in the ocean influence the growth of other marine fishes.
Problems: None.
Key Contact: George Watters (831-648-0623, gwatters@pfeg.noaa.gov)