Biology Ph.D. Dissertations

Assessment of Site-Fidelity and Straying in Lake Erie Steelhead Trout

Richard R. Budnik, Bowling Green State University


This dissertation examines straying in Lake Erie steelhead (Oncorhynchus mykiss) and investigates how stocking practices can influence the propensity of steelhead to stray. The Lake Erie steelhead fishery generates millions of dollars in revenue each year for local economies in New York, Ohio, Pennsylvania, Michigan, and the province of Ontario. This fishery is overwhelmingly dominated by stocking from each of the four contiguous US states, and approximately 1.8 million juvenile steelhead are stocked each year to sustain population numbers. River-spawned salmonids generally exhibit high rates of philopatry, while for stocked fish straying rates of up to 15% are common. In Chapter I, we quantify the proportion of straying adult steelhead in five Lake Erie tributaries using state-hatchery specific otolith chemical signatures to identify sources. We also investigate the prevalence of naturally produced fish and identify spatial differences in the proportion of strays at different stream locations within two Lake Erie tributaries. Because straying proportions were found to be high in New York, in Chapter II an otolith back-calculation method was used to investigate the influence of size at stocking on the survival of juvenile steelhead released by the New York hatchery program. In Chapter III, we investigate additional drivers of straying by using dual-frequency identification sonar (DIDSON) to estimate survival and tributary residence time of juvenile steelhead stocked into a small Lake Erie tributary. Patterns in emigration, and the role of environmental factors and individual size on emigration timing were also investigated. In Chapter IV, we identify the prevalence of aragonite versus vaterite sagittal otoliths in steelhead raised in Lake Erie hatcheries. We then present a technique to use sagittal otoliths that have transitioned from aragonite to vaterite to help develop otolith chemistry signatures of steelhead from different hatchery sources in Lake Erie. This research was an attempt to identify potential drivers of straying in Lake Erie steelhead. From an applied management perspective, we attempted to identify straying proportions in different Lake Erie tributaries and examine how differential stocking practices may influence overall survival and return rates. Straying is a complex process driven by a number of different biotic and abiotic factors. The identification of mechanisms that increase straying, especially those which can be controlled by hatchery managers, would be invaluable and greatly advance our ability to manage steelhead populations.