Study on reproductive biology of Champsocephalus gunnari, Chaenocephalus aceratus and Pseudochaenichthys georgianus from South Georgia and Shag Rocks, Dr Eduardo Holmberg survey - May 2013

MILITELLI, M. I.; MACCHI, G. J.; RODRIGUES, K.

2013-04-01/2013-09-01

1-13

Biológica

Rec.Nat.Renov.-Conservacion y preservacion

The reproductive biology of C. gunnari, C. aceratus and P. georgianus in South Georgia and Shag Rocks Islands was studied. The macroscopic gonad information collected indicated the presence of totally mature females (with hydrated oocytes) of the three species, which confirms spawning of C. gunnari in South Georgia and Shag Rocks Islands and suggests that of P. georgianus and C. aceratus nearby. C. gunnari total fecundity showed a potential fit to size and a linear fit to weight that ranged from 2,500 (27 cm TL) to 21,300 (54 cm TL) hydrated oocytes; for P. georgianus and C. aceratus, of a linear fit to size and weight, values were 6,600 (47 cm TL) - 8,400 (52 cm TL) hydrated oocytes and 7,800 (55 cm TL) - 14,400 (63 cm TL) hydrated oocytes, respectively. Mean relative fecundity reached 21 oocytes/g of female for C. gunnari and 7 oocytes/g for C. aceratus and P. georgianus. It was observed that, in the case of C. gunnari and P. georgianus relative fecundity values decreased as length and weight of females increased. C. gunnari hydrated oocytes diameter and dry weight showed a positive relation to female size which suggest that larger females may produce eggs of better quality than young spawners