Updated 2024-11-22 14:44:57
Lake Superior -> 5.0 Walleye -> Walleye Juvenile Abundance
Reporting Interval
2017 - 2021
Area
Various
Meeting Target?
Does Not Meet
Indicator Trend
No trend
Confidence?
Medium
5.1.1 Juvenile walleye abundance is stable or increasing
Walleye have historically played a significant role in regional fisheries and the fish communities within embayment’s, estuaries, and tributaries of Lake Superior (Hoff 2003). As a result of population specific rehabilitation efforts and their associated monitoring; trends in the status of Walleye on a lakewide scale have been difficult to quantify. Two annual or semi-regular gillnet surveys (Black Bay, ON, and WI-1) that target Walleye provide stock-specific relative abundance estimates provide some indication of walleye status in Lake Superior. These surveys are neither coordinated amongst agencies nor follow a single standardized methodology, making direct comparisons across surveys and stocks challenging. Relative abundance of age-0 and age-1 walleye from Black Bay, ON has been variable through time. Juvenile catch rates in years sampled since 2008 appear to be higher than those observed early in the time series, however, no trend in catch rates is evident in this region of Lake Superior. Similarly, juvenile walleye catch rates in WI-1 (western arm of Lake Superior), conducted by WDNR, have been variable through time, with no discernable trend evident, however, juvenile catch rates in 2021 were the highest in the time series suggesting a strong recruitment event for walleye recently.
Figure 1. Black Bay juvenile walleye catch rates (#/km gillnet)
Figure 2. WDNR WI-1 juvenile walleye catch rates (#/km gillnet)
Methodology
OMNR Black Bay, ON Survey - Fall Walleye Index Netting (FWIN) was conducted in Black Bay in 2002,2008,2010, 2012-2014, 2016 & 2017 . FWIN is a depth stratified graded mesh gillnet survey conducted during September and October when water temperatures are between 10oC and 15oC that primarily targets percid species. Mesh sizes range from 25mm to 152mm stretch mesh. OMNR switched to Broadscale Monitoring (BsM) (North American Gillnet standard NA1) in 2020. BsM is a depth stratified graded mesh gillnet survey conducted during the summer when water temperatures are greater than 18oC. Mesh sizes range from 38mm to 127mm stretch mesh. BsM has become the provincial standard by which the OMNRF surveys inland Walleye fisheries and has been the subject of several peer reviewed papers that look at the relationship between CPUE and fish density; also known as the catchability of the gear and as such a means for translating CPUE into estimates of fish density.
WDNR WI-1 Survey - A summer, graded-mesh gill net survey (12 300-ft panels of 1.5 to 7-inch mesh by 0.5-inch increments) has been conducted in WI-1 waters of Lake Superior during odd years from 1981 to 2021. Length distributions of walleye collected in this survey have signaled recruitment of younger fish in several years throughout the time series, and the magnitude of recruitment levels is measured using the walleye recruitment index, or the geometric mean CPE of walleye in 1.5”-2.0” meshes.
Other Resources
Contributing Author(s)
- Lake Superior Technical Committee -