Using fisheries modeling to assess candidate species for marine fisheries enhancement

- Contribution of stocked fish to fisheries outcomes is influenced by life history and regulatory policies.
- Fishes captured shortly after release contribute better to fisheries outcomes.
- Enhancement of red drum may yield fewer recruited fish but greater harvest than other candidate species.

Selecting target species or stocks in which releases of hatchery fish can contribute effectively to fisheries management goals is a key challenge in many fisheries enhancement programs. Here we show how fisheries modeling informed by stock assessments can be used to evaluate contributions of stocked fish to fisheries and how these contributions are influenced by life history and fishery attributes including regulatory policies and angler effort. We built an age-structured population model to quantitatively assess enhancement contributions to multiple fisheries management objectives: predicted catch, predicted harvest, abundance of catchable fish, abundance of harvestable fish and total spawning biomass. We used this model to evaluate candidate species for marine fisheries enhancement in Florida, where hatchery production capacity is scheduled to expand over the next decade yet it is unclear how fisheries managers can best use this capacity to achieve management objectives. We evaluated five candidate marine fishes in Florida: red drum Sciaenops ocellatus, spotted seatrout Cynoscion nebulosus, common snook Centropomus undecimalis, southern flounder Paralichthys lethostigma and red snapper Lutjanus campechanus. Comparative analysis shows that contribution of released fish to fisheries outcomes tend to decline with increasing time between release and capture or harvest. Enhancement of red drum, a species targeted by anglers during sub-adult life stages, is predicted to yield lower numbers of stocked fish entering the recruited population compared to alternative species but to contribute more to catch and harvest objectives. Our results demonstrate how commonly available biological information can be integrated with quantitative modeling approaches to provide useful information to managers tasked with identifying best uses of increasing enhancement capacity.