Coupling ecology and economy: modeling optimal release scenarios for summer flounder (Paralichthys dentatus) stock enhancement

Increasing interest in the use of stock enhancement as a management tool necessitates a better understanding of the relative costs and benefits of alternative release strategies. We present a relatively simple model coupling ecology and economic costs to make inferences about optimalrelease scenarios for summer flounder (Paralichthys dentatus), a subject of stock enhancement interest in NorthCarolina. The model, parameterized from mark-recapture experiments, predicts optimal release scenarios fromboth survival and economic standpoints for varyious dates-of-release, sizes-at-release, and numbers of fish released.Although most stock enhancement efforts involve the release of relatively small fish, the model suggests that optimal results (maximum survival and minimum costs) will be obtained when relatively large fish (75–80 mm total length) are released early in the nursery season (April). We investigated the sensitivity of model predictions toviolations of the assumption of density-independent mortality by including density-mortality relationshipsbased on weak and strong type-2 and type-3 predator functional responses (resulting in depensatory mortalityat elevated densities). Depending on postrelease density, density-mortality relationships included in the model considerably affect predicted postrelease survival and economic costs associated with enhancement efforts, but do not alter the release scenario (i.e. combination of release variables) that produces optimal results. Predicted (from model output) declines in flounder over time most closely match declines observed in replicate field sites when mortality in the model is density-independent or governed by a weak type-3 functional response. The model provides anexample of a relatively easy-to-develop predictive tool with which to make inferences about the ecological andeconomic potential of stock enhancement of summer flounder and provides a template for model creation for additionalspecies that are subjects of stock enhancement interest, but for which limited empirical data exist.

Bibliographic Details

Main Authors:	Kellison, G. Todd, Eggleston, David B.
Format:	article biblioteca
Language:	English
Published:	2004
Subjects:	Ecology, Fisheries, Management,
Online Access:	http://hdl.handle.net/1834/30886
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