Evidence for egg brooding and parental care in icefish and other notothenioids in the Southern Ocean
One of the least known Antarctic fish species is the icefish Chionobathyscus dewitti described first in 1978. Some of its reproductive characteristics appear to be similar to other channichthyids of similar size and shape. Females close to spawning have gonado–somatic indices (GSIs) of more than 20, and absolute fecundity was 2967 to 15612 oocytes in females 33–62 cm long. Relative fecundity was 7.6 in one female. Spawning has been observed in the Ross Sea at 1300 to 1500 m depth from January to March. Chionobathyscus dewitti may exhibit a remarkable egg carrying behaviour: eggs stick together in batches around the pelvic fins of females. The comparatively large number of mature males observed with no indication of an egg batch attached to their ventral fins makes it unlikely that males are involved in egg carrying. The few larvae of C. dewitti caught so far occurred from October onwards. Their size indicates that they have hatched as early as September. This suggests an incubation period of at least six months. We compare this with parental care reported in other notothenioids.(Received March 24 2005)
(Accepted January 25 2006)
Key Words: Antarctica; Chionobathyscus dewitti; reproductive behaviour; Ross Sea.