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

By Kenneth J E Graham, N. Andrew, K. Hodgson. 2001

179 citations recorded by the source corpus.

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.

Subfields: Nature and Landscape Conservation

View Paper: https://www.semanticscholar.org/paper/ea0f37d9c64b3cf97bd2f0b51159f4873b4b3a8e

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In Nature and Landscape Conservation

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Citations in the corpus

• Limited potential to recover from overfishing raises concerns for deep-sea sharks, rays and chimaeras (2009, background): “There are few data on the effects of fishing on deep-sea chondrichthyans, but those studies available typically show substantial declines (i.e. Graham et al. 2001).”
• Reproduction of the angular angel shark (Squatina guggenheim): geographic differences, reproductive cycle, and sexual dimorphism (2007, background): “The pattern might be common to other angel sharks, because other species have suffered great declines in many regions (Rogers and Ellis, 2000; Vacchi et al., 2000; Graham et al., 2001).”
• Evaluating catch and mitigating risk in a multispecies, tropical, inshore shark fishery within the Great Barrier Reef World Heritage Area (2011, background): “Higher trophic-level predators such as elasmobranchs (sharks and rays) have fared particularly poorly, with some collapses, often rapid, of populations where they are targeted or taken as by-catch (Ripley 1946; Olsen 1959; Graham et al. 2001; Devine et al. 2006).”
• Sharks, rays and abortion: The prevalence of capture-induced parturition in elasmobranchs (2018, background): “These combined life-history traits make them sensitive to overfishing and many population declines have been observed (e.g. Graham et al., 2001; Stobutzki et al., 2002; Cortés et al., 2007; Oliver et al., 2015).”