Publication Date

1987

Series Number

Fisheries Report No 75

Publisher

Fisheries Department, Western Australia

City

Perth

ISBN

07309 1600 6

ISSN

0726 0733

Abstract

The Western Australian-based mixed gear fishery for edible shark generally operates from Geraldton to Esperance in waters shallower than 10 fm to a maximum depth of 100 fm. In 1983/84, the total catch was 1262 tonnes live weight. The total shark catch was taken by 158 gillnet boats, 45 longline boats and 152 handline boats. However, nearly two thirds (62%) of these boats caught 1 tonne or less in 1983/84 and were assumed to rely more heavily on other target fisheries than shark.

Of the 20 or so species of shark caught in W.A., 3 species together comprise two thirds of the total catch by weight. These are whiskery shark (Furgaleus ventralis, 23%), bronze whaler spp. (dominated by Carcharhinus obscurus, 29%) and gummy shark (Mustelus antarcticus , ea. 11%). In some regions other species are more important than gummy shark.

If fishing effort is not taken into account, the trend towards increased annual catch tends to create a false impression of optimism for this fishery. In fact, total fishing effort has grown sharply in the W.A. fishery from 4048 gillnet km.days in 197b/76 to 17170 gillnet km.days in 1983/84, a 420% increase since reliable effort figures first became available from the Australian Bureau of Statistics. Gillnets, which took 90% by weight of the total catch, also contributed most to total fishing effort in 1983/84. During the period compared, the number of gillnet boats increased from 79 in 1975/76 using a mean length of 686 m of net, to 158 boats in 1983/84 using a mean length of 1698 m of net. The maximum length of gillnet used was 6500 m. Longliners set up to 12 000 m of gear. As intra-regional competition for the limited shark resource has increased, so too has effort, and falling catch rates, wherever they occur, have forced some fishermen mainly dependent on shark to leave the industry; to purchase and set more and more gear each year in an attempt to remain economically viable or to place even greater pressure on other fisheries.

Number of Pages

74

Keywords

Commercial shark fishery, Temperate waters, Western Australia, Whiskery shark, Bronze whaler shark, Gummy shark

Disciplines

Aquaculture and Fisheries | Marine Biology | Natural Resources and Conservation | Natural Resources Management and Policy | Survival Analysis | Sustainability

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