Temporal stability in gill raker numbers of subarctic European whitefish populations
Siwertsson, A.; Knudsen, R.; Amundsen, P.-A.
The temporal stability of the distribution of gill raker number in European whitefish (Coregonus lavaretus) populations was monitored through a long-term study of seven subarctic lakes. There is long tradition to identify different morphs of whitefish and other coregonids by the number of gill rakers, which is a heritable morphological trait. This trait is closely associated with the trophic behavior of the fish and rapid changes have been observed following extensive alterations in the selection regime. Contrary to other studies, we found that the gill raker number was stable for up to 24 years within a set of both monomorphic and polymorphic whitefish populations. The observed stability occurred regardless of a variable level of human disturbance including large ecological changes related to the invasion of a zooplanktivore specialist (vendace) and to intensive stock reduction of stunted whitefish. Our findings support the use of gill raker counts as a reliable means to identify European whitefish morphs.