Faculty of Biosciences, Fisheries and Economics, University of Tromsø, N-9037, Tromsø, Norway.
J Fish Biol. 2014 Jun;84(6):1640-53. doi: 10.1111/jfb.12366. Epub 2014 May 2.
The migratory behaviour and spatial area use of sympatric Arctic charr Salvelinus alpinus and brown trout Salmo trutta were investigated during their marine feeding migration. The likelihood of finding individuals of both species in the inner or outer fjord areas was dependent on water temperature in the inner area (especially for S. alpinus), the temperature difference between the inner and outer areas (especially for S. trutta) and fish fork length (both species). The strongest predictor was the water temperature in the inner area, and particularly S. alpinus left this area and moved to the outer areas with increasing temperatures in the inner area. At 8° C in the inner area, the likelihood of finding S. alpinus in the outer areas was >50%. This predictor had a smaller effect on S. trutta, and the likelihood of finding S. trutta in the outer areas only started to increase at around 14° C. The relationships between temperature and area use did not correspond to the species' optimal growth temperatures, but to their previously documented temperature preferences. Individuals of both species used mainly the littoral fjord areas, and to a lesser extent the pelagic areas. In conclusion, temperature differences between the inner and outer marine areas probably resulted in the segregated area use between the species, because water temperatures or factors influenced by temperature affected their migratory behaviour and habitat use differently. The results indicate that increased marine temperatures with global warming may lead to increased spatial overlap between S. trutta and S. alpinus, which again may lead to increased interspecific competition during their marine phase, and with S. alpinus probably being the more negatively affected.
在海洋摄食洄游期间，研究了同域分布的北极红点鲑（Salvelinus alpinus）和褐鳟（Salmo trutta）的洄游行为和空间区域利用。在峡湾内部或外部区域发现这两个物种个体的可能性取决于峡湾内部的水温（特别是对于北极红点鲑）、内部和外部区域之间的温度差异（特别是对于褐鳟）以及鱼叉长（两个物种）。最强的预测因子是峡湾内部的水温，随着内部水温的升高，北极红点鲑离开该区域并迁移到外部区域。在内部区域的 8°C 时，在外部区域发现北极红点鲑的可能性大于 50%。该预测因子对褐鳟的影响较小，只有在内部区域的温度约为 14°C 时，才开始增加在外部区域发现褐鳟的可能性。温度与区域利用之间的关系与物种的最佳生长温度不对应，而是与它们之前记录的温度偏好相对应。两个物种的个体主要利用近岸峡湾区域，较少利用远洋区域。总之，内部和外部海洋区域之间的温度差异可能导致了物种之间的区域利用分离，因为水温或受温度影响的因素对它们的洄游行为和栖息地利用的影响不同。研究结果表明，全球变暖导致海洋温度升高，可能会导致褐鳟和北极红点鲑的空间重叠增加，这可能再次导致它们在海洋阶段的种间竞争增加，而北极红点鲑可能受到的负面影响更大。
