Genetic Effects of Cultured Fish on Natural Fish Populations

TLDR

The study is motivated by rapidly increasing intentional and accidental releases of fish, drawing on empirical observations reported in the literature. The paper investigates the genetic consequences of aquaculture on natural fish populations and recommends stringent restrictions on gene flow and effective monitoring. The authors propose strategies such as secure containment, sterilized fish, altered rearing and release points, and rigorous monitoring to protect native populations from aquaculture effects. Released cultured fish have produced a spectrum of genetic effects—from no detectable impact to complete introgression or displacement—with documented negative effects on performance traits, raising concerns about the genetic future of natural populations.

Abstract

This paper addresses the genetic consequences of aquaculture on natural fish populations. The study is motivated by rapidly increasing numbers of intentionally and accidentally released fish and is based on empirical observations reported in the literature. A wide variety of outcomes, ranging from no detectable effect to complete introgression or displacement, has been observed following releases of cultured fish into natural settings. Where genetic effects on performance traits have been documented, they always appear to be negative in comparison with the unaffected native populations. These findings are consistent with theoretical considerations of the implications of elevated levels of gene flow between cultured and locally adapted natural populations; they raise concerns over the genetic future of many natural populations in the light of increasing numbers of released fish. Strategies for the genetic protection of native populations from the effects of aquaculture are outlined including more secure containment, the use of sterilized fish, and modifying the points of rearing and release. We recommend strong restrictions on gene flow from cultured to wild populations and effective monitoring of such gene flow.