Abstract:

To reveal the age and growth of silver carp (Hypophthalmichthys molitrix) in the middle of the Minjiang River, 126 specimens were collected from June 2015 to March 2017 in the middle of the Minjiang River, the scale rings’ observation and basic biology measurement were conducted to determine the age and growth characteristics. The results showed that the body weight of the silver carp ranged from 310.6 to 9420.8 g, and the body length ranged from 23.4 to 86.9 cm. The scale rings were closed cutting type and had sparse and dense characteristics. The age of the individuals ranged from 1 ⁺ to 7 ⁺, and most of the individuals aged 3 ⁺ to 4 ⁺. The obvious power function relationship between body length (L) and body weight (W) could be expressed as W=0.027×L ^2.953, power exponent approached 3. The silver carp in the middle of the Minjiang River was of the uniform growth type, and its growth could be described by the Von Bertalanfly growth equations: L_t=106.696×[1-e ^{-0.147( t +1.1443)}], W_t=26332.083×[1-e ^{-0.147( t +1.1443)}] ^2.953. The growth inflection t_i=5.923. Compared with silver carps in other water, its growth performance was slightly lower. Therefore, the fist capture of silver carp in the middle of the Minjiang River should be greater than 70 cm length and 7.7 kg weight. At the same time, we should regulate fishing gear and fishing methods to reduce fishing intensity and increase resource conservation efforts, so as to promote the recovery and protection of the silver carp resources in the Mingjiang River.

Key words: Minjiang River, Hypophthalmichthys molitrix, scale, fish age, growth equation, fishing