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14 September 2021 Quantitative Analysis of the Fishery-Independent Queensland Saucer Scallop (Ylistrum balloti) Trawl Survey
Samara M. French, Anthony J. Courtney, Wen-Hsi Yang
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The Queensland saucer scallop Ylistrum balloti fishery is a significant component of the Queensland East Coast Otter Trawl Fishery. In 1996, the saucer scallop stock collapsed, and by 2006, had partially recovered. In 2016, the stock again collapsed, when it was declared, and remains, overfished. In response to the collapses, fishery managers implemented an annual fishery-independent trawl survey of scallop abundance, although funding for the survey has been inconsistent. This study examined 8 y of discontinuous fishery-independent scallop trawl survey data (1997 to 2000, 2017 to 2020). A two-stage approach was introduced to firstly calibrate catch rates for differences between survey vessels for each year, and then derive adjusted mean densities (number ha–1) for the 0+ and 1+ scallop age classes and total scallops, for each year and strata. Quasi-Poisson generalized linear models were used for both stages. Results showed that adjusted mean total scallop densities declined by approximately half from the early survey years (1997 to 2000) to the later survey years (2017 to 2020). Adjusted mean total scallop density and adjusted mean densities of the 0+ and 1+ age classes were lowest in 2020. The 1+ age class numerically dominated survey catch rates.

Samara M. French, Anthony J. Courtney, and Wen-Hsi Yang "Quantitative Analysis of the Fishery-Independent Queensland Saucer Scallop (Ylistrum balloti) Trawl Survey," Journal of Shellfish Research 40(2), 297-309, (14 September 2021).
Published: 14 September 2021
fishery-independent survey
Generalized linear model
Queensland saucer scallop
scallop densities
Ylistrum balloti
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