Characterization and husbandry of wild broodstock of the blackfin icefish Chaenocephalus aceratus (Lonnberg 1906) from the Palmer Archipelago (Southern Ocean) for breeding purposes

The blackfin icefish Chaenocephalus aceratus represents a key component of the fish fauna surrounding the Antarctic Peninsula that may be especially vulnerable to the effects of climate change. Although the sensitivity of adults to elevated temperature has been evaluated, little is known about the potential impact of a warmer temperature on other life history stages including embryos and larvae. To investigate thermal effects on embryogenesis and larval development, one must establish optimal zootechnical parameters for maintaining reproductively competent broodstock in captivity. During two consecutive years, we conducted an evaluation of body morphometrics and reproductive traits and investigated appropriate husbandry practices. Absolute and relative fecundities of females were estimated as 14,367 +/- 5733 and 8.87 +/- 2.35 (Mean +/- SD), respectively. Mean wet and dry masses (+/- SD) of eggs were 24.5 +/- 11.0 and 15.3 +/- 4.8 mg, respectively and the mean egg diameter (+/- SD) was 0.31 +/- 0.03 cm. Post-capture mortality was high and no spawning state females survived for a sufficiently long time to allow release or extraction of mature eggs. Injecting males with gonadotropin-releasing hormone (GnRH) increased their gonadosomatic index by 2-fold and stimulated spermiation. Mean (+/- SD) sperm cell count per mL post-GnRH treatment was 9.9 x 10(9) +/- 2.5 x 10(9), and the spermatocrit was 16.9 +/- 3.8%. Our findings indicate that extending the duration of female survival post-capture will be necessary for the production of fertile eggs. Suggestions for future research are discussed.