Trends in the distribution, species composition and size of sharks caught by Gamefish Anglers off South-eastern Australia, 1961-90

Abstract

Records of shark captures were extracted from the archives of 10 of the major New South Wales gamefishing clubs that operate from ports located between latitudes 33ºs and 37ºs. Although organized game fishing began off eastern Australia in 1936, the majority of catches were made after 1960. Data normally recorded by these clubs included common name of shark, whole weight, locality of capture, boat name and angler. Recognized single species of sharks recorded by these clubs were blue (Prionace glauca), tiger (Galeocerdo cuvier), white (Carcharodon carcharias), shortfin mako (Isurus oxyrinchus) and grey nurse (Carcharias taurus). Species identified only to generic level, and recorded by clubs, were whalers or requiem sharks (Carcharhinus spp.), hammerheads (Sphyrna spp.) and threshers (Alopias spp.). Analysis of catch records indicated that the mako shark was the most common species caught overall, although whaler sharks dominated the catch in the northern part of the study area and hammerhead sharks dominated the catch in the south. Grey nurse and white sharks were relatively rare in the southern part of the study area. Whaler sharks dominated the catch in the 1960s, and the proportions of blue and tiger sharks in the catch increased in the 1980s. Size ranges and distributions of some species also varied through time and by area. Some of the observed changes could be attributed to changed fishing practices, particularly the increasing popularity of tag-and-release and an increasing tendency to fish further from the coast. A marked decline in the number and proportion of white sharks in the catch since the 1970s gives cause for some concern regarding the status of that species off south-eastern Australia.