Data obtained from field trips as part of the current project (FRDC 2008/208) indicate the development of TFS may not be due to inappropriate onboard handling practices. Textural issues appear to be due to a combination of biological, geographical and seasonal factors. Results from the current research suggest a significant influence of both sex and season on the toughness observed in Saddletail Snapper. Current findings do not discount potential compounding influences such as ‘cold shock’ for example. Collagen content and ultimate pH of Saddletail Snapper muscle also represent significant influences of measured toughness. However, these factors alone do not provide a definitive explanation for the toughness observed in the species.
Results to date are provisional only. Further investigation across multiple seasons is required to substantiate or refute observed trends and preliminary statistical correlations. The potential influence of ‘cold-shock’ also needs to be clarified. The limited timeframe of FRDC project 2008/208 will not provide this clarity.
This project is needed to obtain the additional seasonal data to provide a definitive information base which will enable the development of strategies for the management of TFS. This will enable stakeholders to market their product with confidence, achieve an increase in price commensurate with premium quality reef fish and ensure the ongoing sustainable use of the resource.
The resolution of the problem or the adoption of management strategies to minimise the occurrence of TFS will have positive spin offs in all sectors of the supply chain i.e. catcher, buyer, exporter, wholesaler, distributor, retailer, restaurateur, and home consumer.
This proposed project addresses the focus of increasing profitability and optimum utilisation of fish identified by the NT, Qld and WA within their respective current fisheries research and development priority documents.
Final report
A major achievement of this research is the confirmation of fish age being the primary driver of toughness in cooked Saddletail snapper flesh. Knowing the cause provides confidence to develop solutions and make business decisions for the reef fish fisheries.
The influence of other fish physiological factors was shown to have little impact with respect to fish flesh toughness. Additionally, there was no apparent connection between flesh toughness and seasonality nor year to year conditions. The possibility of toughness being engendered through in appropriate chilling immediately post capture was ruled out as a factor contributing to tough fish syndrome (TFS).
The outcome following on from identification of the cause of TFS surrounded developing procedures for reducing the incidence of tough fish where the cause was preventable . However, as post-harvest handling was not a contributor to toughness, implementing alternative handling procedures was irrelevant. The focus of this outcome shifted to developing strategies to ensure fish at risk of exhibiting TFS did not enter the value chain. This was addressed by provision of currently available technology on non-invasive ultrasonic imaging and near infrared spectroscopy (NIRS) to the industry partners.
Keywords: Saddletail snapper, Lutjanus malabaricus, flesh toughness, fish texture, fish age, consumer perception
