Enzymatic polymorphism was used to detect variability within Notothenia rossii from two sites on the Kerguelen Plateau and Champsocephalus gunnari from the same sites and the South Orkney Islands. No polymorphism was found in the second species and it was low but not statistically significant in the first. This apparent homogeneity does not substantiate suggestions from other results that the populations can be separated, especially in the case of C. gunnari. Other approaches will be necessary to solve definitively the question of population separation.

During winter research cruises to South Georgia (1983 and 1993) fish eggs were abundant in the neuston. Examination of the external sculpturing and the micropyle morphology of the eggs collected during 1993 using scanning electron microscopy indicated that these were fertilized ova of Notothenia rossii marmorata. A comparison between the eggs of N. rossii from Iles Kerguelen and South Georgia showed these to have a similar surface morphology but a difference in the structure of the micropyle. In 1993, the abundance of fish eggs in the neuston varied from 0-116 eggs m−3 with an average of 4.5 eggs m−3. During 1983, eggs were most abundant in the neuston but at lower average levels (0.04 eggs m−3, range 0–1.17 eggs m−3) and these were distributed from the surface to >380 m.