Bruising patterns in commercially harvested yellowtail flounder (Limanda ferruginea)

Abstract

a b s t r a c tFillet discolouration, commonly known as bruising, is an unintended and undesirable consequence in many commercial fishing operations. The purpose of this study was to develop a method to objectively measure and characterize the size and location of discolouration patterns that are currently observed in the fillets of commercially harvested yellowtail flounder (Limanda ferruginea) on the east coast of Canada. To accomplish this, an image processing program was developed to analyse fillet discolouration patterns. Total discoloured area and percent fillet coverage were measured and compared to total bruise weight and percent bruise weight attained from manual assessment. Results revealed that bruising was evident in 86.5% of the fish sampled. Of all the parameters measured, fish weight was the only parameter correlated with bruise weight. Bruise area ranged from 0 to 124.5 cm 2 , with a mean of 12.1 cm 2 (s.d. = 21.4), and accounted for an average of 4.3% of fillet area. Bruises were not uniformly distributed on any of the fillet sides. Results revealed a strong tendency for bruising to occur at the anterior dorsal region of the fillet, commonly known as the "nape". Functional explanations for this finding are provided, including recommendations for future research.

Testing the effect of soak time on catch damage in a coastal gillnetter and the consequences on processed fish quality

“…Most of the processed plaice produced in Denmark is sold as frozen fillets (FAO, 2014). Bruises do not impair the taste of fillets, but they are not attractive to consumers, and the fish processing factory would usually remove the part of the flesh with these marks, which reduce fillet weight and final profit (Kenney, Rahman, Manuel, & Winge, 2015;Roth et al, 2007). Marks on the fins and tail may not impair the yield in fillet as it is standard procedure to remove these parts during filleting.…”

Digital image analysis of flatfish bleeding injury

“…Although cost efficient and simple to perform, ratings typically involve an abstraction and interpretation of criteria, which might be influenced by experience, cognitive ability, and other personal traits, and hence might be biased (Meagher 2009, Burghardt et al, 2012Tuyttens et al, 2014;Meeremans et al, 2017). Digital image analysis may offer an alternative to deliver more accurate and repeatable results in a standardized procedure (Balaban et al, 2011;Davis and Ottmar, 2006;Kenney et al, 2015). To quantify the amount of bleeding injury using normal white light (as opposed to fluorescent or polarized light; Davis and Ottmar, 2006;Balaban et al 2011, respectively), Kenney et al, 2012 described procedures for North American yellowtail flounder (Limanda ferruginea), focusing on detecting discolorations among photographed fillets as a quality indicator.…”