Investigations into fish quality for last year's autumn-spring herring fishery was undertaken by Bord Iascaigh Mhara, BIM, on the basis of a series of onboard investigations on both traditional dry hold polyvalent vessels and refrigerated-seawater, RSW, pelagic vessels. The aims of this study included: ascertaining the effectiveness of temperature management throughout the catching cycle – that is, from the net right through to the fish processor – and monitoring the development of histamine and TVB-N in fish products as a quantitative measure of fish quality.
The results from BIM's study show that the average TVB-N levels at point of landing for both dry hold polyvalent vessels and RSW pelagic vessels were not dissimilar. Indeed, of the samples tested, both cases recorded levels of TVB-N were 17 mg N/100g. For histamine, the levels recorded from dry hold polyvalent vessels were, on average, two parts per million and those recorded from RSW pelagic vessels were, on average, 0.8 parts per million. In both cases, the recorded levels were significantly less than the level stipulated in Council Directive 91/493/EEC laying down health conditions for the production and placing on the market of fishery products and the level currently demanded in the marketplace. While the average temperature of herring from dry hold polyvalent vessels measured on landing was 4ºC higher than similar landings from RSW pelagic vessels, the BIM study went on to show that with proper temperature management post landing, average temperatures of fish from both dry hold polyvalent and RSW pelagic vessels was approximately 7ºC.
These studies, which focused on the traditional fisheries pursued by the dry hold polyvalent fleet where fishing trips are short due to the proximity of the fishing grounds, clearly demonstrated that with proper temperature management both on board vessels and post landing, the temperature and quality of fish from both dry hold and RSW pelagic vessels more than meet market place requirements. Fishing vessels which fish pelagic stocks further offshore and remain fishing for several days are typically dedicated pelagic vessels fitted with refrigerated seawater systems that enable the effective chilling of large volumes of fish.
