Identifying survival of hatchery Cisco in northern Lake Michigan using otolith microchemistry

Session: Restoration and Management of Great Lakes Fishes (4)

Gary Michaud, United States Geological Survey , [email protected]

Abstract

Cisco have been the focus of native species restoration in the Great Lakes over the last few decades and stocking is being explored as a viable option to enhance natural reproduction. Laser ablation is commonly used to identify stock structure using chemical signatures obtained from sagittal otoliths. The process involves analyzing the otolith’s chemical signature through mass spectrometry and comparing it to signatures from the water.  Ideally, different regions of a lake or different tributaries have unique water signature owing to differences in geology or watershed characteristics. Managers value this information because it can identify productive spawning or nursery habitat .  We explored the feasibility of laser otolith ablation to detect survival of hatchery-stocked cisco in northern Lake Michigan embayment’s.  We collected larval Cisco from various locations in 2017 and created a classification model based on otolith chemical signatures. Larval otolith signatures differed between Grand Traverse Bay, Little Traverse Bay, and the Little Traverse Bay Bands of OdawaIndians (LTBB) Hatchery. Overall, LDA proved successful in identifying hatchery larvae (100%) and was able to classify 88% of the data correctly. Across three years of collections of age-1+ ciscoes in Little Traverse Bay, 2/39 individuals were identified as hatchery origin.