Identification of Antarctic fish eggs by surface structure as shown by the eggs of Trematomus eulepidotus (Teleostei: Nototheniidae)

Abstract

Oocytes and incubated eggs of the antarctic nototheniid fish Trematomus eulepidotus were observed with a scanning electron microscope to investigate whether their surface structures show a similar pattern. Oocytes were taken from the ovary or were stripped from running females. For comparison, incubated eggs of stages I and IV (classification after Apstein 1909) were sampled from a bottom trawl catch. We found no significant differences in surface pattern and interpore distances. This finding is of main importance for the determination of unknown incubated eggs from ichthyoplankton samples by SEM. T. eulepidotus exhibited a micropyle of type III in unfertilized eggs. Some incubated eggs were covered by hyphae of fungi, which resemble attaching-filaments of substrate spawning fishes.