The Yukon River gillnet fishery may be the only remaining fishery in the world that targets Chinook salmon (Oncorhynchus tshawytscha) with largemesh gear. Concern regarding potential consequences of the selective removal of large fish is being expressed with increasing frequency among fishery professionals and in public meetings. Investigations attributing changes in population size and structure (i.e., the age, sex, and size composition of a population) to selective fisheries are common in the literature. However, relatively few of these investigations concern salmon, and even fewer consider Alaskan Chinook salmon. Exploratory analyses of data collected during typical harvest sampling or stock assessment activities are hampered by the short time series of available data, as well as high levels of natural variation. In addition, if the decades-old Yukon River Chinook salmon fishery has the capability of modifying population structure, the effects may now be largely manifested and investigations founded on available data, collected only in recent years, may be uninformative. For these reasons, we propose to evaluate the potential longterm effects of large-mesh gillnet fisheries on Yukon River Chinook salmon by stochastic modeling of population dynamics. Parameters of primary interest include the productivity and age, sex, and size structure of Yukon River Chinook salmon. If results suggest that long-term effects are probable, the resiliency of the population to alternative harvest strategies will be explored.
Our overall objective is to construct a realistic model of Yukon River Chinook salmon population dynamics to facilitate investigation of the potential for selective fisheries to impose changes to population structure and productivity. There are numerous specific objectives that one might list; the subset we wish to pursue follow. Develop a model of Yukon River Chinook salmon that is temporally stable over multiple generations in the absence of exploitation, with a plausible level of natural variability. Model the effect of various levels of selective exploitation on the productivity and age, sex, and size structure composition of Yukon River Chinook salmon. Evaluate the sensitivity of results obtained under Objective #2 to moderating selective pressures to maintain population structure. Evaluate the resiliency of the population to partially or fully regain original population structure and productivity under alternative harvest-management strategies. Evaluate the information content of data obtained post-exploitation with respect to preexploitation productivity.
Jeff Bromaghin
jeffrey_bromaghin@fws.gov
U. S. Fish and Wildlife Service
907-786-3559
Fisheries and Ecological Services
1011 E. Tudor Road
Anchorage
AK
99503
A Final Report is available for this project: Click to view First Year Funding: $183,005.00
A Project Authorization Statement is available for this project: Click to view
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Keyword Tree for Project
Fields of Expertise
Biological Science
Population Biology - 26 Other Projects
Physical Science
Socio/Economic
Professional Activity
Management analyst - 2 Other Projects
Ecosystems
Freshwater – Rivers/Streams - 45 Other Projects
Ecosystem Components
Fish - 51 Other Projects
Species Groups
Anadromous salmonids - 51 Other Projects
Chinook - 22 Other Projects
Specific research issues
Catchability and selectivity - 1 Other Projects
Geographic Regions
Yukon River Watershed - 21 Other Projects
Technological Expertise/Lab Methods
Lab Methods
Technology
Modeling
Method
Type
Physical Science Specialties Areas
Management/Policy/Social
Fishing gear performance - 2 Other Projects