Fecundity of Individual Fish Pseudobagrus truncatus

Total of 63 female Pseudobagrus truncatus whose ovaries at stage Ⅳ were collected from the Yangtze River's tributaries-Minjiang river from April to May in 2013. The body length( L),body weight( M),net body weight( W),ovary weight( Wa) of the sampled fish were measured. The age of sampled fish was determined by lapilli,egg diameters were measured by vernier caliper. The individual absolute fecundity( F)was obtained by gravimetric method,then it was used to calculate the relative fecundity per centimeter( FL),relative fecundity per gram( FW),coefficient of maturing( GSI),fullness( K),and other indices. Based on these measurements and calculations,the relationship between the individual fecundity and the morphologicalindices of 63 female specimens of P. truncatus was studied. The results showed that the age of the specimens ranged from 2+to 5+years old( Table 1). The individual absolute fecundity( F) ranged from 566 to 6 758eggs( average 3 056 eggs). The individual relative fecundity per centimeter( FL) ranged from 68 to 469 eggs( average 234 eggs) and the individual relative fecundity per gram( FW),ranged from 45 to 349 eggs( average145 eggs)( Fig. 3). The absolute fecundity and length relatively fecundity was power correlated with body length,body weight and maturing coefficient( GSI),respectively. While weight relative fecundity was only power correlated with the maturing coefficient( GSI),but not correlated with other morphological indices.Multi-regressive analysis showed that the individual absolute fecundity was significantly correlated with body weight and maturing coefficient( GSI),the relative fecundity per centimeter was significantly correlated with body weight,net weight and maturing coefficient( GSI) while the relative fecundity per gram was only correlated with maturing coefficient( GSI). The multiple stepwise regression equation were as follow: F =16 370. 714 + 3 284. 028 GSI + 58. 361 M( n = 63,R2= 0. 973,P 0. 01); FL= 251. 749 + 18. 961 M +684. 273 W + 3 268. 421 GSI( n = 63,R2= 0. 852,P 0. 01); FW= 138. 590 + 837. 641 GSI( n = 63,R2= 0. 539,P 0. 01). Based on the distribution of egg diameter,this species of fish spawns once a year.