Highly Variable and Elevated Straying Rates of Steelhead Trout from Lake Erie Tributaries

In Lake Erie, the fishery for steelhead trout is overwhelmingly dominated by smolt stocking from each of the four contiguous US states. We have quantified the occurrence of straying in adult steelhead trout (Oncorhynchus mykiss) in five Lake Erie tributaries (fall and spring) using state-hatchery specific otolith chemical signatures to identify sources of these fish.  Laser-ablation-inductively-coupled-plasma-mass-spectrometry (LA-ICP-MS) was utilized to quantify the otolith chemistry of known origin (hatchery reared) yearling steelhead trout.  Linear discriminant analyses were conducted using Sr and Ba concentrations from nine otolith regions, enabling the hatchery stocks to be accurately discriminated. In addition, naturally reproduced yearlings from Cattaraugus Creek New York were distinguished with high accuracy.   The origin of adult steelhead trout from five Lake Erie tributaries were then identified, allowing the proportions of strays to be calculated. The observed straying rates range from 12.9% in 16-Mile Creek, PA, 17.7% in Vermillion River, OH, 31.8% in Huron River, MI, 77.6% in Chautauqua Creek, NY, to 87.8% in Cattaraugus Creek, NY.  While straying rates in Ohio and Pennsylvania tributaries are consistent with observations for salmonids in other systems, a large proportion of adult steelhead trout in the New York streams were strays from other state stocking programs.