**ABSTRACT NOT FOR CITATION WITHOUT AUTHOR PERMISSION. The title, authors, and abstract for this completion report are provided below.  For a copy of the full completion report, please contact the author via e-mail at erin.dunlop@ontario.ca or via telephone at 705-755-2296. Questions? Contact the GLFC via email at frp@glfc.org or via telephone at 734-662-3209.**

Mortality influences on maturation scheduling in lake whitefish and effects on great lakes fisheries management

Yolanda E. Morbey¹, Yingming Zhao², Erin S. Dunlop³

¹Department of Biology

The University of Western Ontario

1151 Richmond St, London N6A 5B7

²Ontario Ministry of Natural Resources and Forestry

Lake Erie Fishery Station,

320 Milo Rd, Wheatley, ON, N0P 2P0

³Ontario Ministry of Natural Resources and Forestry

2140 East Bank Drive

Trent University, DNA Bldg

Peterborough, ON, K9J 7B8

April 2017

ABSTRACT:

The purpose of this study was to evaluate whether fishing could cause evolution of maturation schedules in lake whitefish stocks in Lake Huron. Our approach was to rigorously examine the assumptions underlying fisheries induced selection and evolution as they relate to specific lake whitefish stocks. We first quantified the patterns of size-selectivity imposed on lake whitefish by commercial gill net and trap net harvest in Lake Huron. We also characterized spatial and temporal variation in growth and maturation schedules, which have been driven, in part, by major ecosystem changes in Lake Huron. We then built predictive models to investigate 1) whether size selective fishing is an important selective agent on maturation schedules and 2) how fisheries-induced evolution affects fish population dynamics and the implications for stock assessment and management. Although the gear used to commercially harvest lake whitefish is size-selective and despite fairly significant harvest pressure, it is not a major selective agent on maturation schedules, likely because fish are harvested after they reach maturation. In addition, growth rate variation appears to drive life history dynamics. Thus, we predict that lake whitefish stocks in Lake Huron are not experiencing a substantial degree of fisheries-induced selection for earlier maturation as has been observed in several marine stocks. However, if gear mesh sizes or size limits are reduced and fishing pressure increases, more substantial rates of fisheries-induced evolution of maturation are predicted, with fundamental effects on population growth rate, resilience, and yield dynamics. These changes in turn could lead to poor performance of stock assessment models, thus having implications for fisheries management. The overall results of our study indicate that ecological and evolutionary dynamics interact to determine stock responses to anthropogenic stressors, for lake whitefish and other valuable fishery resources in the Great Lakes.