Factors influencing return-to-creel of hatchery catchable-sized Rainbow Trout stocked in Idaho lentic waters

Abstract

In recent years, increases in hatchery rearing and transport costs coupled with stagnate or declining funding has often resulted in reduced numbers of hatchery fish stocked in public waters. This has intensified the need to better understand how to maximize return-to-creel rates of hatchery trout by identifying factors contributing to better post-stocking performance. From 2011 through 2014, we tagged 50,745 catchable-sized hatchery Rainbow Trout Oncorhynchus mykiss and stocked them into 54 different lentic waters in Idaho (mostly impoundments) across 226 individual stocking events. Angler tag returns (n = 5092) were used to generate water-specific estimates of angler return rates (i.e., the proportion of stocked fish caught by anglers) and average days-at-large of captured fish. We then modeled water-specific angler return rates and days-at-large against a suite of water- and stocking-specific characteristics to determine what factors most influenced both angler returns and fishery longevity. First-year angler return rates across all four study years averaged 23% and ranged from 0% to 76% for individual stocking events; the variation in angler returns was best explained by mean fish length at stocking, water size, rearing hatchery, and water elevation. Average days-at-large for angled fish in individual waters varied from a low of 10 d to a high of 297 d, and this variation was best explained by water size, stocking season, and the rearing hatchery. We found the highest angler returns for larger trout stocked into smaller waters at lower elevations. However, these smaller waters also had shorter fisheries, requiring more frequent stocking to prolong the fisheries through the entire angling season. When considering these findings, managers must also consider the balance between angler catch, effort, and satisfaction as they work towards maximizing the benefit to anglers from put-and-take fisheries.