Maturity, spawning and fecundity of the streaked seer, Scomberomorus lineolatus (Cuvier & Valenciennes), In the Gulf of Mannar and Palk Bay

Abstract

The ovary of streaked seer passes through 12 finer maturity stages,-A to L, of which all but A show bimodality in the ova-size-frequency distribution. The growth of the advanced mode (first batch) through successive stages takes place at slightly less than two times the growth of the preceding mode (second batch) except from stage G to H when the growth of the advanced mode is nearly five times the growth of the preceding mode. After most of the ova in the first batch are spawned at the first ripe stage J, the second batch of ova at stage K, which resembles the advanced mode of stage G, grows abruptly (like the growth from G to H) into and is spawned at the second ripe stage L. The duration of 96 days taken for the growth from stage B to L includes 75 days from B to J and 21 days from J to L. Gonad index values separating the spawning from the nonspawning females range from 3 at the 441-480 mm length group to 5 at the 961-1000 mm group. The fish attain first maturity when about 700 mm total length when they are about 2 years old. Each year class is composed of one weak brood produced in the period January to early March, a dominant brood during mid-March to end of May and another weak brood in late June to late July. Spawning takes place in inshore waters up to a distance where the ciepih is about 25 m. There is no lunar periodicity in spawning. Males and females occur in the ratio of 40.5 : 59.5. The increase in fecundity per 10 mm body length is 65,998, whereas the fecundity per ton of spawning females is 570 million.