Image-based quantification of size, color, and image texture in meagre (Argyrosomus regius (Asso, 1801)) reared in different culture systems

Meagre is an important fish both regarding fisheries and aquaculture. Visual attributes of whole meagre are important for the purchase intention of consumers. Whole meagre grown in cages and earthen ponds were evaluated by image analysis for visual attributes (length, view area, color of right and left sides, image texture). The fish were weighed, and images of both sides were taken. Weight W vs length L data were fitted a power equation W = A LB. The B values for cage and earthen pond fish were 2.95 and 2.93, respectively. The R2 values for power fit to weight vs view area were 0.976 for cage fish, and 0.983 for earthen pond fish, respectively. The 1st null hypothesis was that the colors of cage and earthen pond-reared fish were not different. The 2nd null hypothesis was that for both type fish the colors of the right and left colors were not different. Specifically, the cage fish were lighter than the earthen pond-reared fish. The L*, a* and b* values of cage fish were statistically different than those of earthen pond fish (p<0.05). The a* values of both sides of cage and earthen pond fish, and b* values of both sides of cage fish were statistically different (p<0.05). Delta E values between the right and left skin colors for cage and earthen pond fish were 1.89, and 1.78, respectively, suggesting noticeable difference upon close examination. Also, there were 13 out of 53 Delta E values greater than 3 for cage fish, and 10 out of 66 for earthen pond fish. Texture change index and color change index of cage and earthen pond fish were statistically different (p<0.05). This suggests considering both sides of the fish should be considered in evaluating color and image texture.