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Changes in relative abundance of sharks and rays on Australian South East Fishery trawl grounds after twenty years of fishing

Journal Article


Abstract


  • Upper continental slope trawling grounds (200-650 m depth) off New South Wales were surveyed with the same vessel and trawl gear and similar sampling protocols in 1976-77 (during the early years of commercial exploitation) and in 1996-97. The 1996-97 mean catch rate of sharks and rays, pooled for the main 15 species (or species groups), was ���20% of the 1976-77 mean. Individual catch rates were substantially lower in 1996-97 for 13 of the 15 species or species groups. The greatest decline was observed for dogsharks of the genus Centrophorus, which were most abundant in 1976-77 but rarely caught 20 years later. In contrast, 1996-97 catch rates of spiky dogshark (Squalus megalops) and, to a lesser extent, whitefin swell shark (Cephaloscyllium sp. A) were similar to those in 1976-77. Trawling during 1979-81 provided data for nine species, albeit not corrected for larger gear size, and the pooled mean catch rate for sharks and rays in the depth range 300-525 m was ���28% of the mean for 1976-77. The results suggest that the biomass of most species of sharks and rays declined rapidly as the fishery developed and is now at very low levels.

Publication Date


  • 2001

Citation


  • Graham, K. J., Andrew, N. L., & Hodgson, K. E. (2001). Changes in relative abundance of sharks and rays on Australian South East Fishery trawl grounds after twenty years of fishing. Marine and Freshwater Research, 52(4), 549-561. doi:10.1071/MF99174

Scopus Eid


  • 2-s2.0-0034792195

Start Page


  • 549

End Page


  • 561

Volume


  • 52

Issue


  • 4

Place Of Publication


Abstract


  • Upper continental slope trawling grounds (200-650 m depth) off New South Wales were surveyed with the same vessel and trawl gear and similar sampling protocols in 1976-77 (during the early years of commercial exploitation) and in 1996-97. The 1996-97 mean catch rate of sharks and rays, pooled for the main 15 species (or species groups), was ���20% of the 1976-77 mean. Individual catch rates were substantially lower in 1996-97 for 13 of the 15 species or species groups. The greatest decline was observed for dogsharks of the genus Centrophorus, which were most abundant in 1976-77 but rarely caught 20 years later. In contrast, 1996-97 catch rates of spiky dogshark (Squalus megalops) and, to a lesser extent, whitefin swell shark (Cephaloscyllium sp. A) were similar to those in 1976-77. Trawling during 1979-81 provided data for nine species, albeit not corrected for larger gear size, and the pooled mean catch rate for sharks and rays in the depth range 300-525 m was ���28% of the mean for 1976-77. The results suggest that the biomass of most species of sharks and rays declined rapidly as the fishery developed and is now at very low levels.

Publication Date


  • 2001

Citation


  • Graham, K. J., Andrew, N. L., & Hodgson, K. E. (2001). Changes in relative abundance of sharks and rays on Australian South East Fishery trawl grounds after twenty years of fishing. Marine and Freshwater Research, 52(4), 549-561. doi:10.1071/MF99174

Scopus Eid


  • 2-s2.0-0034792195

Start Page


  • 549

End Page


  • 561

Volume


  • 52

Issue


  • 4

Place Of Publication