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- Interbreeding between local and translocated populations of a cleaner fish in an experimental mesocosm predicts risk of disrupted local adaptationPublication . Gonzalez, Enrique Blanco; Espeland, Sigurd H.; Jentoft, Sissel; Hansen, Michael M.; Robalo, Joana Isabel; Stenseth, Nils Christian; Jorde, Per ErikTranslocation of organisms within or outside its native range carries the risk of modifying the community of the recipient ecosystems and induces gene flow between locally adapted populations or closely related species. In this study, we evaluated the genetic consequences of large‐scale translocation of cleaner wrasses that has become a common practice within the salmon aquaculture industry in northern Europe to combat sea lice infestation. A major concern with this practice is the potential for hybridization of escaped organisms with the local, recipient wrasse population, and thus potentially introduce exogenous alleles and breaking down coadapted gene complexes in local populations. We investigated the potential threat for such genetic introgressions in a large seminatural mesocosm basin. The experimental setting represented a simulated translocation of corkwing wrasse (Symphodus melops) that occurs on a large scale in the Norwegian salmon industry. Parentage assignment analysis of mesocosm's offspring revealed 30% (195 out of 651 offspring) interbreeding between the two populations, despite their being genetically (FST = 0.094, p < 0.05) and phenotypically differentiated. Moreover, our results suggest that reproductive fitness of the translocated western population doubled that of the local southern population. Our results confirm that human translocations may overcome the impediments imposed by natural habitat discontinuities and urge for immediate action to manage the genetic resources of these small benthic wrasses.
- Growth and age structure in captive and wild stocks of the endangered western ruivaco Achondrostoma occidentale (Cyprinidae)Publication . Mameri, D.; Santos, Carla Sousa; Robalo, Joana IsabelDeclines in freshwater fish populations are occurring at a fast rate, increasing the importance of ex-situ conservation programs supported by sound knowledge of population dynamics and life-history traits of the target species. We analysed the growth and age structure of wild and captive stocks of the western ruivaco Achondrostoma occidentale, a Portuguese endangered cyprinid, targeted for captive breeding and restocking since 2007. Specifically, we compared maximum size, longevity, and length-at-age among captive and wild populations, restocked and non-restocked. We found considerable variation in length-at-age and longevity between captive-bred and wild fish, with the former generally growing faster and living longer. Analysis of length-age distributions among wild populations suggested a positive effect of restocking actions in fish abundance. Results highlight the value of captive breeding for the conservation of endangered cyprinids, and reinforce the need for detailed data on life-history trait variation between captive and wild stocks to assess the efficiency of ex-situ conservation programs.