The Selection of Stocking Locations for Fisheries Enhancement in the Estuarine Environment: A Decision Support Tool

Abstract

Stock enhancement is an important tool for fisheries management agencies around the world, and survival of stocked individuals is vital to the success of enhancement activities. This is especially true when fish are stocked as juveniles. Suitable nursery habitat is known to increase the survival of juvenile fishes. Several logistical constraints to the stocking process (e.g., differences in environmental conditions between the hatchery facility and stocking sites) may similarly influence the survival of stocked individuals. The objective of this project was to construct a decision support tool for the selection of stocking locations. I trialed this tool for three species stocked in Corpus Christi Bay, Texas: Red Drum Sciaenops ocellatus, Spotted Seatrout Cynoscion nebulosus, and Southern Flounder Paralichthys lethostigma. The decision support tool incorporated three layers: a species‐specific habitat suitability model (accounting for suitable salinity, temperature, seagrass presence, and seasonality), a layer comparing the similarity of salinity in hatchery grow‐out ponds to salinities in the bay system, and a layer comparing the similarity of water temperature in hatchery grow‐out ponds to temperatures in the bay system. Outputs of stocking suitability were found to vary regionally throughout the bay system based largely on the intra‐estuary variation in salinity (through both the habitat suitability model and the grow‐out pond salinity model) and the presence of seagrass (as specified in the habitat suitability model). Outputs from this tool will be greatly improved as input data sources are refined and as managers adapt the use of this tool to specific drivers of postrelease survival for their specific application.

Temperature regulates sex determination and growth in the paralichthid flatfish California halibut

“…Other competing factors that could impact production, such as the effect of temperature on malpigmentation (MacNamara et al, 2023), also need to be considered. For stock enhancement, release timing can be strategized to occur either before or after the thermosensitive period (depending on the targeted size-at-release) or to ensure that temperature in the hatchery and at the release location are in harmony (e.g., Olsen, 2019). The growth data presented here for California halibut show that regardless of temperature, there are intrinsically fast and slowgrowing individuals within a cohort.…”