The possibility of using river hopper barges as aquaculture facilities

Abstract

The aim of this study is to explore the possibilities of introducing the new technology of intensive carp (Cyprinus carpio) farming in a floating vessel. The experiment was conducted on an out-of-use hopper barge on the Danube. Water was pumped in from the Danube using two pumps with a total power of 1 kW. The farming was conducted in two barge compartments with volumes of 40 m³, from June 5th to November 5^th 2009. The first compartment was stocked with 800 (20 ind./m³), and the second one with 400 individuals (10 ind./m³) of juvenile carp, with an average weight of 420 g. The fish were fed 6 mm granulation pellet feed containing 38% proteins. The daily amount of feed varied during the experiment in the range of 1.2-2.7% of the stock weight. Indicators of water quality were measured daily (temperature, pH, dissolved oxygen, concentrations of ammonia, nitrites, nitrates and phosphates) both within the barge and in the Danube. It was determined that amounts of dissolved oxygen were bellow optimal values for intensive carp farming and often dropped bellow 3 mg/l. During periods of low oxygen concentrations the fish were not fed, and thus the number of feeding days (87) was lower than the duration of the experiment (153 days). Despite this, weight gain values were 97.23% for the first, and 94.8% for the second compartment, while feed conversion ratios were 1.89 in the first, and 1.95 in the second compartment. Mortality was low, 1.88% in the first, and 3.25% in the second compartment. These values are considerably better than those from fish farming in ponds and cages. Furthermore, a comparison of fish meat quality between carps raised in the experiment and those raised in a classic fish pond system has revealed no difference in quality. The obtained results, although preliminary, indicate that it is possible, with certain technical improvements, to achieve high yields from barges, with significantly lower expenditure on feed and negligible negative effects on the environment.