2019 Sturgeon For Tomorrow Research

Lake Sturgeon Research and Stocking Summary

By Doug Larson, Research Assistant I, Michigan Department of Natural Resources, Michigan State University

The 2019 Black Lake research season began on April 26th when Michigan State University (MSU) and Michigan Department of Natural Resources (MDNR) researchers captured 3 adult Lake Sturgeon ascending the Upper Black River. Radio Frequency Identification (RFID) data suggests that Lake Sturgeon Adults were in the river on April 18th, 2019, MSU sampled the river from April 26th, 2019 – May 30th, 2019.

A total of 293 adult Lake Sturgeon were captured during the spawning season, of which 47 were captured for the first time (16.07%). Of the first time captures, three fish showed signs of hatchery origin. The largest single day capture was on May 9th, where the crew sampled 28 fish. The largest fish captured this year was a 6.4‐foot female that weighed 137 pounds. Gametes were collected from spawning Lake Sturgeon and transported to the Streamside Rearing Facility for fertilization and rearing. In total 1,159 unique individual Lake Sturgeon have been captured in the Upper Black River since 2001.

In addition to raising eggs in the hatchery, wild larval Lake Sturgeon were captured as they drifted downstream. Previous research conducted by MSU and MDNR found that wild larvae represent the highest quality genetic source stock, so MSU and MDNR make an effort to fulfill all stocking quotas with fish captured in the wild, where possible. This year, larval drift sampling began on May 30th and continued until July 7th. Researchers captured 2,437 wild dispersing larvae at Site D, the fewest captured in a single season since 2015. As part of a graduate project, staff collected larval fish at two additional sites: The historical site for the sawmill and site C. In total researchers caught 6,131 drifting larvae across 15 drift nights. A contributing factor to the low drift numbers was the period extending from June 9th – June 20th in which rain events kept water too high for crew sampling.

In 2019, 520 Lake Sturgeon were released into the Black River. All fish that were stocked into the Black River were implanted with a passive integrated transponder tag, which will aid future management efforts. In addition, 521 Lake Sturgeon were released into Mullet Lake, all of which were implanted with a PIT tag.

At the direction of the Lake Sturgeon committee and in collaboration with the United States Fish and Wildlife Service, Black Lake Sturgeon for Tomorrow, and Michigan Sea Grant, 130 fall fingerling Lake Sturgeon were released into the Titabawassee, Flint, Shiawassee and Cass Rivers, respectively as part of an ongoing rehabilitation and research effort. This project will continue at an approximate density of 125 Lake Sturgeon from the Black River Streamside Rearing Facility for the foreseeable future.

The Sturgeon released in 2019 reached an average length of 3.75 inches. This decline was likely to the sharp decline in average temperature in 2019. Indeed, the number of days exceeding 24°C (75°F), which averages 30±2 days in a typical year, was zero in 2019. Sturgeon growth is heavily dependent on temperature (Eckes et al. 2015; Black River, Unpublished Data) Increased size at stock out can be attributed to an improved feeding strategy developed and published by John Bauman.

During the fall juvenile Lake Sturgeon assessment, we captured 1 fish across 4 nights. Researchers conducted a mark‐recapture assessment across four transects from the mouth of the river to Red Bridge nightly from dusk until completion during the week of July 29th, 2019. This assessment resulted in a calculated population estimate of 1; (95% CI; Lower: 0, Upper: ‐‐) Lake Sturgeon in the lower 4km of the Upper Black River.

Research efforts in 2019 focused on factors contributing to reproductive success; particularly those that can be quantified by data collected from Radio Frequency Identification (RFID) antennas placed throughout the Upper Black River including migratory strategy, inter-annual migratory trade‐offs and sperm quality. Additionally, 2019 marked the beginning of a project evaluating the factors contributing to olfactory imprinting by age‐o Lake Sturgeon. Graduate Student Jake Kimmel raised Lake Sturgeon under differing water combinations (ground water, Black River Water) to differentiate when Age‐0 Lake Sturgeon imprint on their natal water. Additionally, Jake monitored the changes in amino acid consistency in the Upper Black River as this has shown to differentiate imprinting in salmonid smolts. Analysis of that data is ongoing. Research evaluating the behavioral ecology of Lake Sturgeon in the context of modified stress environments both in the wild and the hatchery was completed in 2019. Two publications were produced from this work. Continuing research through MSU includes: the selective properties of female lake sturgeon ovarian fluid; down‐stream outmigration of drifting Lake Sturgeon and the consequences for recruitment; behavioral plasticity as a function of intraspecies reproductive competition and its consequences for current and future reproduction; the interaction of predatory and herbaceous macroinvertebrates, fungi, antibiotics and lake sturgeon eggs; and feeding efficiency of Lake Sturgeon in the hatchery.