Age structure, growth rate and exploitation pattern of Cirrhinus mrigala (Ham. 1822) in Vallabhsagar reservoir, Gujarat, India

Abstract

Mrigal, Cirrhinusmrigala (Ham.1822), one of the Indian major carps widely distributed in Indian inland waters, has considerable aquaculture potential. Knowledge on factors such as age, growth and exploitation pattern is important in fisheries management. Here, we investigated the age structure, growth increment and exploitation pattern of mrigal in Vallabhsagar reservoir, Gujarat (India). Age composition of thestudied fish was 1+ to 9+ age groups with mean total lengths 40.78, 50.99, 59.82,66.32,70.72, 74.56, 77.80, 80.22 and 82.50 cm. The corresponding growth rate in terms of length were 40.78, 10.21, 8.83, 6.50, 4.40, 3.84, 3.24, 2.42 and 2.28 cm observed for these age groups. The growth increment was maximum at the initial age group whereas it was moderate to low in the subsequent years of the age. The exploitation patterns of fish were 3.94 for +1, 32.02 for +2, 22.17 for +3, 25.12 for +4, 2.96 for +5, 6.16 for +6, 4.43 for +7, 2.46 for +8 and 0.74% for +9 age classes. Results depict that exploitation pattern of fish was high at early age fish stock than the higher age classes. The exploitation pattern for 1+ to 3+ age classes was 58.13%, and 41.87% contributed by 4+ to 9+ age classes. Higher catch rate of younger fishes is not a good sign for natural stocking of fish i.e., mrigal in the Vallabhsagar reservoir