Observations on variations in physico-chemical water parameters of marine fish cage farm off Karwar

Abstract

An investigation was undertaken to study the fluctuations in the water quality parameters in a marine fish cage culture site off Karwar during the period 2009-2011. Two stations viz., one from cage site (Station 1) and the other away from the cage site (Station 2) were selected for the study. Water samples were collected at weekly intervals. Temperature of Station 1 varied from 28.5 ± 0.89 oC to 32.5 ± 1.04 oC during the first crop of Asian seabass culture in 2009-10 and it ranged between 26.7 ± 0.83 to 32.5 ± 0.79 oC during the second crop of seabass culture in 2010- 11. The salinity was minimum during July 2010 and maximum in May 2010. There was no significant difference observed between the water quality parameters of the two stations (p>0.05). However, difference in salinity was significant between the two culture periods in Station 1 (p<0.05). No significant difference was observed in the nutrient levels of the cage and reference sites and also between the two crops. No significant difference was observed between the mean weight of the fish and temperature of both the sites and periods. A positive correlation was observed between the weight gain of fish and salinity of water at cage site.