Relative Cost and Post‐Release Performance of Hatchery Catchable Rainbow Trout Grown to Two Target Sizes

Abstract

Catchable‐sized hatchery trout (hereafter, catchables) have become a staple component of many fisheries management programs throughout North America. Due to their size, catchables create immediate fisheries once they are stocked, and fisheries managers have gradually shifted towards stocking fewer, larger trout. However, the cost of growing larger fish may reduce the efficiencies of catchable stocking programs overall. We grew catchable‐sized Rainbow Trout Oncorhynchus mykiss to two target average sizes (254 and 305 mm total length) at a production scale, while tracking feed expenditures to examine the costs and benefits associated with increased size‐at‐stocking. Although larger catchables cost 31% more in feed expenditures than those reared to a smaller average size, catch (by anglers) of larger fish increased by 100% relative to smaller fish. Consequently, if target stocking size was changed from 254 to 305 mm and feed costs were held constant by reducing the total number of fish stocked, anglers would benefit by catching larger and more fish, despite the reduction in number of fish stocked. In lentic systems, larger catchables were reported by anglers more quickly than smaller fish, so managers must consider interactions between stocking size and residence time for lentic systems supported by catchables. In lotic systems, overall catch by anglers was much lower than catch at lentic waterbodies, and all catchables were either reported by anglers quickly or failed to be reported at all regardless of size‐at‐stocking. Producing larger catchables for hatchery‐supported fisheries serves to benefit angling and would likely increase angler satisfaction while improving efficiencies associated with hatchery catchable stocking programs.