Abundance and Population Structure of Walleye in Milk River Ridge and Forty Mile Coulee Reservoirs, 2012
Walleye (Sander vitreus) populations throughout Alberta experience high angling pressure, and are characterized by late-maturity and slow growth rates, resulting in many populations being susceptible to over-exploitation. In 1995, Alberta Natural Resources Service implemented the Alberta Walleye Management and Recovery Plan (AWMRP), to facilitate the protection and recovery of exploited walleye fisheries. As part of the AWMRP, and to monitor the effectiveness of the management strategy for Milk River Ridge and Forty Mile Coulee reservoirs, Alberta Conservation Association conducted Fall Walleye Index Netting (FWIN) surveys in September 2012.
Relative abundance of walleye in Milk River Ridge Reservoir was 19.8 fish/100 m2/24 h. Sizes of walleye ranged from 105 to 690 mm fork length (FL), with 100 to 150 mm FL as the strongest length class. Fish age ranged from young-of-the-year (yoy) to 14 y, with strong yoy and 2 y age-classes. Overall, growth rates were slow with an estimated maximum size of 797 mm FL for females, and 587 mm FL for males. Male walleye in Milk River Ridge Reservoir reach maturity by age 3, and females by age 7.
Relative abundance of walleye in Forty Mile Coulee Reservoir was 18.7 fish/100 m2/24 h. Sizes of walleye ranged from 203 to 686 mm FL, with the majority of the population in the 450 to 600 mm FL size ranges. Fish age ranged from 1 y to 15 y, with strong 6 y and 9 y age-classes. Walleye had moderate growth rates with an estimated maximum size of 683 mm FL for females, and 521 mm FL for males. Male walleye in Forty Mile Coulee Reservoir reach maturity by age 3, and females by age 5.
The information collected in these surveys will provide current data to Alberta Environment and Sustainable Resource Development (AESRD). These data will assist AESRD in making accurate management decisions regarding the walleye sport fisheries and populations in these reservoirs.