Porównanie strategii żerowania kozy Cobitis taenia complex (Linneusz, 1758) i kozy bałtyckiej Sabanejewia baltica (Witkowski, 1994) (Pisces, Cobitidae)

Abstract

Comparison of the foraging strategies of spined loach (Cobitis taenia complex) and northern golden loach (Sabanejewia baltica) was conducted. Due to current limited knowledge on the nutritional biology of both species, diel research of fish diet was conducted in: spring, summer and autumn. Because the sensory organs responsible for finding food may affect differences in the feeding efficiency of these fishes, the structure of the olfactory organ of both species was examined. The stomach fullness index of S. baltica was higher than for spined loach. Both species showed similar patterns of foraging activity in spring and summer, with S. baltica having a more diversified foraging activity over a twenty-four hour period. There were differences in the diet between size classes of both species in all seasons. No differences were found in the habitat preferences of prey between individuals of the same species. The width of the food niche of C. taenia was twice as high as that for S. baltica. A high diet similarity was found between loach species, both can be considered as opportunistic. The surface structure of the olfactory receptor epithelium in both loach species was similar, but S. baltica had a greater number of olfactory lamellae. The average area of a single spined loach lamellae was significantly larger, but the total area of the olfactory lamellae of both loach species did not differ. S. baltica individuals had a larger total surface area of the olfactory epithelium than individuals of C. taenia with the same body length.