Pectoral fin development in the Baikalian viviparous golomyankas (Comephoridae; Cottoidei), with a remark on eggs and embryos of Comephorus baicalensis (Pallas)

Abstract

Measurements of pectoral fin (PF) growth in relation to standard body length (SL) for Comephorus dybowskii (SL: 14-126 mm) and C. baicalensis (SL: 22-173 mm) were made and compared with corresponding data obtained for 13 other Baikalian cottoid species (sculpins). The allometry for the PF/SL relationships (Y = a + bX) is clearly biphasic. Expressed in percentages, these values for the larval period of C. dybowskii [Yp = -28.886 + (2.419X)] are much higher than for C. baicalensis [Yp = -11.904 + (1.233X)]. The postnatal period of development of the golomyanka up to 30-35 mm SL is considered to be the larval stage. In the postlarval period, growth of pectoral fin and the body in C. dybowskii are directly proportional [Yp' = 48.92 + (-0.009X)] whereas in C. baicalensis they rise slightly [Yp' = 30.966 + (0.0505X)]. Absence of the air bladder characterizes all Baikalian cottoid species, including the golomyankas. Various species of the golomyanka differ in the ways of obtaining neutral buoyancy. It is supposed that large pectoral fins guarantee behavioural buoyancy in small species such as C. dybowskii, whereas in C. baicalensis, obtaining much larger body size but lower PFp/SL index, the buoyancy is gained mainly due to the accumulation of large amount of lipids. This paper also documents the ovary and advanced embryos of C. baicalensis.