Morphological characteristics of fins of the Baikal omul’s spawning herd Coregonus migratorius (Georgi) of three morpho-ecological groups

Abstract

A comparative characteristic of the meristic and plastic features of the fins of the spawning part of the population of three morpho-ecological groups (coastal, bottom-deep and pelagic zones) of the Baikal omul, which are in a depressed state, is given. In the bottom-deepwater and coastal MEG, in relation to the pelagic MEG, the greatest difference in dimension is noted in such features as: the height of the dorsal fin (by 2.14% l Sm), the height of the anal fin (by 1.5% l Sm), the length of the caudal stems (by an average of 2.17% l Sm), the length of the abdominal and pectoral fins (in average 1.64% l Sm). The difference in the length of the base of the anal (0.17% l Sm) and dorsal fins (0.49% l Sm) is less pronounced. Thus, the greatest differences in dimension are noted in the height of the dorsal, anal fins, the length of the pectoral, ventral fins and caudal stems. The difference in the length of the base of the anal and dorsal fins is less pronounced. During the period of anthropogenic load, there is no obvious, significant variability of morphological signs associated with the movement of fish of the Baikal omul. Sexual dimorphism is traced. In males, the indices of the signs of the studied fins are greater than in females by an average of 0.7% of the length according to Smith. A greater limit value of soft rays is observed in bottom-dwelling fish in the abdominal (up to 15 pcs.) and anal (up to 14 pcs.) fins, while in pelagic up to 12 soft rays in the compared fins. In bottom-dwelling fish, a greater number of soft rays are noted in the abdominal and anal fins, which are responsible for fish stabilization, rapid ascent in the vertical plane, rotation and abrupt stop.