| Title | Limited contribution of hatchery-produced individuals to the sustainment of wild marble trout (Salmo marmoratus Cuvier, 1829) in an Alpine basin |
| Abstract | Fish stocking constitutes a common management practice in freshwaters all over the world, to enhance fisheries or to support threatened fish populations. Pervasive detrimental effects may affect the real effectiveness of stocking programs. However, studies assessing the real impacts and relative contribution of stocked trout in wild populations are surprisingly few.
The marble trout, Salmo marmoratus (Cuvier 1829), is a critically endangered sub-endemic salmonid in Northern Italy, and an iconic species for recreational fishing and conservation, also representing an emblematic case of species negatively affected by restocking. For instance, marble trout inhabiting the Toce River, the second largest tributary of Lake Maggiore, has been stocked with different hatchery congener trout belonging to the Salmo trutta complex (putative marble trout, Atlantic trout Salmo trutta Linnaeus 1758 and putative Mediterranean trout Salmo ghigii Pomini 1941) over the last decades. Using mitochondrial (D-loop) and nuclear (12 microsatellites and LDH-C1*) markers, we characterised the genetic variability and gene flow among the wild and hatchery individuals of marble trout of this basin, to investigate the effectiveness of stocking activities on the native residual population.
Despite extensive hybridization of marble trout with non-native brown trout stocks was shown, the presence of individuals belonging to pure native stock has been detected as well. However, concerns could be advanced regarding its future persistence, due to climatic and hydraulic instabilities or loss of environmental heterogeneity. Moreover, despite ongoing yearly massive stocking activities, a negligible contribution of reared putative marble trout in the wild sample has been documented, suggesting that natural recruitment represents the greatest source of this wild population sustainment. Important adaptive differences between wild and domestic trout are present, likely due to the deleterious long-term effects of the close breeding system of hatcheries. Finally, possible implications for stocking management improvement have been discussed. |
| Source | Science of the total environment 892 |
| Keywords | Salmo marmoratusStockingFish conservationIntrogressive hybridizationConservation genetics |
| Journal | Science of the total environment |
| Editor | Elsevier, Lausanne ;, Paesi Bassi |
| Year | 2023 |
| Type | Articolo in rivista |
| DOI | 10.1016/j.scitotenv.2023.164555 |
| Authors | Tommaso Righi,, Emanuele Fasola, Mattia Iaia, Fabrizio Stefani,, Pietro Volta. |
| Text | 489000 2023 10.1016/j.scitotenv.2023.164555 Salmo marmoratus Stocking Fish conservation Introgressive hybridization Conservation genetics Limited contribution of hatchery produced individuals to the sustainment of wild marble trout Salmo marmoratus Cuvier, 1829 in an Alpine basin Tommaso Righi,, Emanuele Fasola, Mattia Iaia, Fabrizio Stefani,, Pietro Volta. CNR Istituto di Ricerca sulle Acque Fish stocking constitutes a common management practice in freshwaters all over the world, to enhance fisheries or to support threatened fish populations. Pervasive detrimental effects may affect the real effectiveness of stocking programs. However, studies assessing the real impacts and relative contribution of stocked trout in wild populations are surprisingly few. The marble trout, Salmo marmoratus Cuvier 1829 , is a critically endangered sub endemic salmonid in Northern Italy, and an iconic species for recreational fishing and conservation, also representing an emblematic case of species negatively affected by restocking. For instance, marble trout inhabiting the Toce River, the second largest tributary of Lake Maggiore, has been stocked with different hatchery congener trout belonging to the Salmo trutta complex putative marble trout, Atlantic trout Salmo trutta Linnaeus 1758 and putative Mediterranean trout Salmo ghigii Pomini 1941 over the last decades. Using mitochondrial D loop and nuclear 12 microsatellites and LDH C1 markers, we characterised the genetic variability and gene flow among the wild and hatchery individuals of marble trout of this basin, to investigate the effectiveness of stocking activities on the native residual population. Despite extensive hybridization of marble trout with non native brown trout stocks was shown, the presence of individuals belonging to pure native stock has been detected as well. However, concerns could be advanced regarding its future persistence, due to climatic and hydraulic instabilities or loss of environmental heterogeneity. Moreover, despite ongoing yearly massive stocking activities, a negligible contribution of reared putative marble trout in the wild sample has been documented, suggesting that natural recruitment represents the greatest source of this wild population sustainment. Important adaptive differences between wild and domestic trout are present, likely due to the deleterious long term effects of the close breeding system of hatcheries. Finally, possible implications for stocking management improvement have been discussed. 892 Published version https //www.sciencedirect.com/science/article/pii/S0048969723031765 Articolo in rivista Elsevier 0048 9697 Science of the total environment Science of the total environment Sci. total environ. mattiaiaia IAIA MATTIA FASOLA EMANUELE RIGHI TOMMASO pietro.volta VOLTA PIETRO fabrizio.stefani STEFANI FABRIZIO |
