Using Swimming Speed as an Indicator of Malformation: A Practical Approach for Identification and Removal of Juvenile Seabass (Dicentrarchus labrax L., 1758) with Skeletal Deformity

Abstract

Skeletal abnormalities in farmed fish are one of the main problems that negatively affect the production enterprises in terms of economic, biological and animal health. Fish with skeletal deformities in hatcheries are considered as non-economic individuals and are therefore detected and removed manually from the production tanks, which is a time consuming and laborious work for the facilities. Since the formation of abnormalities in the skeletal structure of the fish during the early growth period cause reduced swimming ability or speed that prevent fish to compete during feeding. Further, since deformed fish has no market value, even the share of a small amount of feed among deformed fish will reduce the feed conversion for the market targeted individuals within the culture tank that in terms may increase the production cost per fish. Therefore, in culture conditions it is important to remove the deformed fish from the tank environment by quickly determining those fellows at the early stage of growth. The present study evaluates the effects of water velocity on swimming behavior of juvenile seabass (Dicentrarchus labrax) and provides a solution for a rapid identification -and mechanical removal of deformed fish from the culture environment by using swimming speed slowdown -and behavioral differences as an indicator of deformation.