Reproductive strategies of three deep-water benthopelagic fishes from the northeast Atlantic Ocean

The reproductive strategies of three benthopelagic species of deep-water fish from the northeast Atlantic were studied: Helicolenus dactylopterus (245–800 m depth), Coryphaenoides rupestris (400–1500 m depth) and Alepocephalus bairdii (650–1700 m depth). The reproductive strategies and fecundity of the females of the three species were studied over a 2-year sampling period (December 1995–December 1997). H. dactylopterus reproduced from March to June and oocyte development within the population was synchronous. Annual fecundity was indeterminate, but batch fecundity ranged from 1212 to 20 504 oocytes per female. Reproduction in C. rupestris extended from February to November with a maximum from May to November. Oocyte development within the population was not synchronous. Annual fecundity was indeterminate, but batch fecundity was estimated to be between 4078 and 68 780 oocytes per female. The precise period of reproduction for A. bairdii could not be determined; however, mature fish were found throughout the year with a major spawning period from January to April. Oocyte development within the population was not synchronous. Annual fecundity was indeterminate, but batch fecundity was estimated at 458–7049 oocytes per female. There was a trend for an increase in the duration of the reproductive period and a decrease in synchronicity of maturation with increasing depth. A long spawning period and asynchrony in maturation may be partially explained by the lack of marked cyclic environmental factors in the deep sea.