Feeding patterns of post-larval and juvenile notothenioids in the southern Weddell Sea (Antarctica)

Summary The food of 163 juvenile specimens of 13 species of notothenioid fishes collected in the southern Weddell Sea (Antarctica) was analyzed. Investigated fish size range was 3–13 cm SL. Principal food items were calanoid copepods Metridia gerlachei, Calanoides acutus, and Calanus propinquus; all developmental stages of Euphausia crystallorophias, and post-larval nototheniid fish Pleuragramma antarcticum. Diet of juvenile channichthyids is limited to few species of euphausiids and fish in the size > 10 mm, but does not include significant numbers of copepods. Pelagic stages of nototheniids feed on copepods and/or larval euphausiids smaller than 10 mm. At similar size, nototheniids and bathydraconids take smaller prey items than channichthyids.     

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

Summary 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.     

Sardine Sardinops sagax and anchovy Engraulis encrasicolus larvae avoid regions with low dissolved oxygen concentration in the northern Benguela Current system

Larvae of sardine Sardinops sagax and anchovy Engraulis encrasicolus in the northern Benguela upwelling system were distributed predominantly in waters with dissolved oxygen concentrations >2·0 ml l⁻¹ and oxygen saturations >75%.