Investigation of rainbow trout (Oncorhynchus mykiss) culture in marine floating cages in the Southern Caspian Sea

Abstract

There is no long history of fish farming cages in the southern Caspian Sea. The rainbow trout is one of the most important fish raised in the last decade in this sea. The aim of this study was to determine the growth performance and survival of rainbow trout (Oncorhynchus mykiss) in floating cages in the south of the Caspian Sea. In this study, circular polyethylene floating cages with a diameter of 20 meters and a net height of 8 meters were used. The cages were located at a depth of 32 meters in the sea and at a distance of 5.6km from the shore. This research was conducted in 2017-2018 in a marine farm in the central region of the southern Caspian Sea. The fish culture period was 165days from December to May of the following year. For each cage, 37400±570 fish weighing 110±28grams and a fork length of 19.9±1.9cm were introduced. After 165 days, the average weight of fish reached 1200±168g in the marine fish farm. But, the fish yield was supplied with a weight of 700g to the local market, from March and continued to June of the following year (1200g). Fish average daily growth (ADG:g/day) was 6.61±1.02. The value feed conversion ratio of fish and the condition factor was determined 1.03±0.07and 1.42±0.05respectively. The fish special growth rate (SGR:%day-1) was determined1.44±0.09.The fish survival rate (SR%) at the end of during culture wasdetermined95.6±1.07 in cages. The results showed that the growth performance of rainbow trout was suitable in the Caspian Sea's brackish water in floating cages.