Environmental and fishing effects on the dynamic of brown tiger prawn (Penaeus esculentus) in Moreton Bay (Australia)

This analysis of the variations of brown tiger prawn (Penaeus esculentus) catch in the Moreton Bay multispecies trawl fishery estimated catchability using a delay difference model. It integrated several factors responsible for variations in catchability: targeting of fishing effort, increasing fishing power and changing availability. An analysis of covariance was used to define fishing events targeted at brown tiger prawns. A general linear model estimated inter-annual variations of fishing power. Temperature induced changes in prawn behaviour played an important role in the dynamic of this fishery. Maximum likelihood estimates of targeted catchability ($3.92 \pm 0.40 \ 10^{-4}$ boat-days$^{-1}$) were twice as large as non-targeted catchability ($1.91 \pm 0.24 \ 10^{-4}$ boat-days$^{-1}$). The causes of recent decline in fishing effort in this fishery were discussed.Comment: revised manuscript following reviewers comments + adding data and code for reader

Stock Assessment of Ballot's saucer scallop (Ylistrum balloti) in Queensland

This assessment estimates the status of saucer scallops in the main fishing grounds of the Queensland Southern Inshore fishery. The stock assessment data inputs included total harvests, standardised catch rates and fishery independent density estimates.   Analyses suggested that spawning biomass in 2019 fell to around 17 per cent of the unfished level. The report presents recommendations on fishing effort levels to begin rebuilding the stock to levels consistent with 40 per cent of unfished biomass

Quantitative assessment of the Queensland saucer scallop (Amusium balloti) fishery

In recent years (2015 and 2016) there has been growing concern from members of the fishing industry and the Queensland Government over declining catches of legal-sized saucer scallop. This led to a request in mid-2016 by Fisheries Queensland, the fisheries management service within the Department of Agriculture and Fisheries, for an investigative analysis of the status of saucer scallops. The scope of the investigation was limited to a short time frame of three months to urgently analyse the most recent data and undertake a stock assessment. This report provides findings that support the concerns about low abundance of legal-sized scallops. Average catch rates from January 2015 to April 2016 were the lowest in the 39-year record. These recent average catch rates are slightly lower than those in 1996 when the scallop population size fell to low levels and emergency closed areas were implemented by the Government. From these data the model estimates of spawning stock in 2015 are potentially as low as 5-6% of 1977 levels, when the fishery was in its early development