Spatial ecology of juvenile lake sturgeon (Acipenser fulvescens) in the Detroit River

DRJLS

July 2017 - July 2021

Improved understanding of the movements and habitat use of juveniles is needed to improve habitat restoration planning for lake sturgeon for Lake Sturgeon (Acipenser fulvescens) in the Great Lakes. Compared with adults, much less is known about the movements, dispersal, and habitat selection of juveniles, but this information is critical for identifying habitats for protection, designing and siting habitat restoration projects that meet the needs of individuals throughout ontogeny, and for monitoring juvenile abundance in response to habitat enhancement projects. The Detroit River is an international area of concern (AOC), but supports a remnant Lake Sturgeon population that has been the focus of numerous habitat restoration projects. Juveniles in the system are known to inhabit only two areas, one in the lower river (the “river” site) and one in Lake Erie at the confluence with the river mouth (the “lake” site). The primary goal of this project is to determine if these locations represent isolated patches of nursery habitat used by different groups of juveniles or if juveniles use both the river and lake sites on a seasonally recurring basis. A second goal is to understand whether juvenile site fidelity is better explained by the “restricted range” or “home-range shift” hypothesis. To address these questions, juvenile Lake Sturgeon were captured at the lake site during 2017-2019 and surgically implanted with acoustic tags. Half the individuals were released at the site of capture while the remaining half were translocated to the river site or a second lake location. Both translocation sites are located 10 km from the lake (i.e., capture) site. Movements of acoustic-tagged juveniles monitored on a network of acoustic receivers throughout the Detroit River and Lake Erie then were used to address the objectives below.

• Study objectives are to determine:
• 1. if non-translocated juveniles from the lake site are detected at sites within the Detroit River and whether detection probability on river sites depends on season.
• 2. The probability that translocated juveniles return to their original capture site and whether the probability of return depends on the type of translocation (river, lake), body size (total length), or their interaction.

• Results are expected to help fishery managers and scientists determine if juvenile lake sturgeon in the Detroit River and in other large river systems require large sections of uninterrupted high-quality habitat (corridors) or whether they utilize discrete patches of habitat in a sequential fashion as they age (habitat “stepping-stones”). Results also will inform design of a juvenile lake sturgeon monitoring program, data from which will be used to develop an index of juvenile abundance needed

• Darryl Hondorp (United States Geological Survey) - dhondorp@usgs.gov
• Justin Chiotti (United States Fish And Wildlife Service)

• United States Geological Survey - Great Lakes Science Center
• United States Fish and Wildlife Service

• USGS-Science Support Program