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

The reproductive biology of C.gunnari, C. aceratus and P.georgianus was studied on samples taken around South Georgias and Shag Rocks. The macroscopic analysis indicated the presence of totally mature females of three species (with hydrated oocytes). C. gunnari, C. aceratus and P. georgianus  This not only confirms the spawning time of C.gunnari in South Georgias and Shag Rocks, but also suggests spawning of P.georgianus and C.aceratus. C. gunnari batch fecundity showed a potential fit to size and a lineal fit to weight and ranged from 2,500 (27 cm TL) to 21,300 (54 cm TL) hydrated oocytes. Batch fecundity values for P.georgianus and C.aceratus showed a lineal fit to size and weight, they ranged between 6,600 (47 cm TL) and 8,400 (52 cm TL) hydrated oocytes and 7,800 (55 cm TL) and 14,400 (63 cm TL) hydrated oocytes respectively. Mean relative fecundity values were 21 oocytes/g for C.gunnari and 7 oocytes/g for C.aceratus and P.georgianus. In the case of C.gunnari and P.georgianus, it was observed that relative fecundity decreased with increasing length and weight of the females. Diameter and dry weight of C.gunnari’s hydrated oocytes showed a positive relationship with female size.