MATURATION OF THE NIGHT SHARK, CARCHARHINUS SIGATUS, IN THE SOUTHWESTERN EQUATORIAL ATLANTIC OCEAN

摘要

Over 700 night sharks, Carcharhinus signatus, comprising 327 females and 4l7 males were collected from semi-pelagic longliners operating throughout the south-western equa- torial Atlantic between October l992 and May l997. Analysis of various morphometric relationships showed significant differences between males and females for regressions ofprecaudal length (PL) and interdorsal space (IS) and for total weight (TW) and evicerated weight (EW) and headless finned and evicerated weight (HW). A common log EW/log TL regression was calculated for both sexes: log EW =-l2.03 + 2.93 log TL. Females and males were categorized into maturation stages (5 and 3, respectively) according to morphological changes in their gonads. The majority of specimens were sexually imma- ture. The size at sexual maturity for females was estimated at between 200 and 205 cm TL, While males mtheed at between l85 and l90 cm TL. A seasonal peak in male GSI during spring, combined with evidence of female ovulation shortly after suggests that copulation occurs in suminer Gravid females had between four and l5 pups varying in total length from l0 to 40 cm.