Sharks caught in the protective gill nets off KwaZulu-Natal, South Africa. 12. The African angel shark Squatina africana (Regan)

  • RL Shelmerdine Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen, UK, AB24 2TZ; current address: Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Dunbeg, Oban, UK, PA37 1QA
  • G Cliff Natal Sharks Board, Private Bag 2, Umhlanga 4320, South Africa

Abstract

Between 1980 and 2001, a total of 661 African angel sharks Squatina africana was caught in the protective nets off KwaZulu-Natal, South Africa. The mean annual catch was 30 sharks (range = 11–69, SD = 12.4), with no trend in catch rate over the study period. Individuals were caught throughout the year and through much of the netted region, with a higher catch to the south. The sex ratio of the catch was 2.9 females:1 male. Males matured between 640mm and 700mm and females at about 700mm precaudal length (PCL). Mature males had clusters of thorn-shaped denticles, each about 2mm high, near the anterio-dorsal margins of both pectoral and pelvic fins. Of the mature females, 44% were pregnant, many of which contained only ova in utero. Embryos were present from April through to January. The average litter size was six, with length at parturition at least 240mm PCL. Most early-term pregnant females and all mature males were caught in the south. The reproductive cycle showed some seasonality and appeared to be biennial, with a gestation of about one year. Teleosts were the most common prey (76% of stomachs with food), followed by cephalopods (52%).

Keywords: cpue; distribution; embryos; gill nets; length frequency; length-weight relationships; maturity; nursery grounds; reproduction; seasonality; stomach contents

African Journal of Marine Science 2006, 28(3&4): 581–588
Published
2006-12-08
Section
Articles