Protecting population integrity with genetic refuges

Posted on March 26, 2010

Although stocking of waterways with hatchery-reared fish is a common strategy in the management of freshwater fisheries, stocking can destroy the genetic integrity of local populations and threaten fitness.  In rivers of theEastern Pyrenees, the release of hatchery-reared brown trout has led to hybridisation with native populations.  However, beginning in 1997, a number ofPyreneesriver locations have been declared as genetic refuges, where releases of hatchery stocks are completely banned.  The repeated sampling of fish from refuge and non-refuge populations, and the use of a genetic marker (the LDC-C*90 allele, which is fixed in hatchery stocks but absent in wild populations), suggests that the introduction of genetic refuges has managed to contain previously increasing rates of hybridisation.  Local differences in the hybridisation rate indicate that the effectiveness of refuges can be enhanced by other management measures, such as limits on the numbers and size of captured fish.  For example, genetic refuges in headwaters can be buffered by downstream catch-and-release zones where native fish dominate the adult population and discourage the migration and reproduction of hatchery-released fish from further downstream.

Reference:  Araguas, R.M., Sanz, N., Fernandez, R., Utter, F.M., Pla, C. & Garcıa-Marin J.-L.  2008.  Genetic refuges for a self-sustained fishery: experience in wild brown trout populations in the eastern Pyrenees.  Ecology of Freshwater Fish 17, 610–616.