Age, growth, and reproductive biology of the blackbelly rosefish from the Carolinas, U.S.A.

Abstract

Otoliths and gonads of blackbelly rosefish Helicolenus dactylopterus dactylopterus were collected from the commercial fishery off the Carolinas in 1994–1997. Opaque bands on transverse sections of otoliths were determined to be annuli by analysis of marginal increments. Opaque zone formation occurs between July and January. Ages ranged from 7 to 30 years. Blackbelly rosefish have intraovarian gestation. Fertilization is internal, as free spermatozoa were found primarily in resting ovaries from July through early December with peak occurrence in September through November. There was a delay of 1–3 months before fertilization, as oocyte development did not begin until December. Occurrence during January through April of early‐celled embryos, the most advanced stage observed, and postovulatory follicles indicated that oocyte development was rapid. Egg development occurs in a clear gelatinous matrix secreted into the ovarian cavity. The reproductive mode is a zygoparous form of oviparity, intermediate between oviparity and viviparity. Population sex ratio departed markedly from 1: 1 for most length intervals. Males were more abundant at lengths >250 mm LT and the overall male: female ratio was 1 : 0·60.