Exploring Life History Characteristics of Naturalized Versus Stocked Chinook

Grant: # 1198

Grant Amount: $256,107.00

Board Decision Year: 2011

U.S. Geological Survey - Lake Erie Biological Station (Sandusky)

Lake Erie Biological Station

Rogers, Mark ([email protected]) 734-214-9324

GLFT - Ecosystem Health and Sustainable Fish Populations-D - Ecological and biological fisheries research to inform management

Project Details

Naturalization of stocked populations can result in divergence of life-history traits from domestic stocks. Lake Michigan supports popular Chinook salmon fisheries that have been sustained by stocking since the late 1960s. Natural recruitment of Chinook salmon in Lake Michigan has increased in the last few decades and currently contributes over 50 percent of Chinook salmon recruits. Samples collected as part of a lakewide mass marking of Lake Michigan Chinook salmon, starting with the 2006 year class, indicated hatchery fish average 30 millimeters longer and 130 grams heavier than naturalized fish at age one. Researchers hypothesized that selective forces differ for naturalized and hatchery populations resulting in divergent life-history characteristics, with implications for Chinook salmon population production and the Lake Michigan fishery.

In general, results from this project did not indicate significant life-history divergence between naturalized and hatchery-stocked Chinook salmon populations in Lake Michigan. Researchers found weak evidence of changes in spawner demographics in a historical analysis and few significant differences from a field study that sampled naturalized, mixed, and hatchery-stocked populations. There were significant differences in egg thiamine concentrations between mixed and naturalized Chinook salmon spawning populations, but the hatchery-stocked population did not differ from the other types. The future demographics of Lake Michigan’s Chinook salmon spawning population cannot be fully discerned from these analyses and field study, but for now there appears to be relative stability with environmental variability.


2011.1198 Final Report
View - Rogers_chinook_final_report_v2.pdf