Journal of the Marine Biological Association of India

Volume 40 Issue 1&2

Food and feeding habits of the spotted seer, Scomberomorus guttatus (Bloch and Schneider) in the Gulf of Mannar and Palk Bay.

M. Devaraj

Tbc spotted seer, essentially a surface feeder, feeds on a limited number of about five species, of which the sardines are the most important and the whitebaits the next The ration per active feeding (R) in 1968-69 declined by 50% of the 196748 level.owing to shortage of food. The shift from whitebaits which constitute the exclusive diet of the young, to sardines which form the major food of the adult, takes place at .about 315 mm, about 114 the asymptotic length. The fish is far less aggressive than the kingseer or the streaked seer as evident from ih inability to compete ably in times of food shortage, the much larger size at which it shifts to feeding on larger forage species and the orientation of 68.4% of the forage fish in its stomach in its reverse axis. The spotted seer is numerically more abundant, but gravimetrically less abundant than the kingseer, and thenfore, its poor catch by weight must be seen more as a function of its small size than as a function of compctena or competitiveness. 

Thas are two active feedinga a day, one between 7 and 10 p.m. and the other between 6 and 10 a.m. Food intake did not slacken in maturing or ripe fish and was generally high from September to March. Young fish less than 300 mm length, distributed in nearshore areas were found much better fed than the adults in grounds beyond the 20 meter depth line. Young spotted seer (say, 1 to 3 year old) consume more food per unit body weight than old Fih (say, 4 year old), but the former require much less food to produce a unit weight growth than the latter. The T-line suggests that the ration available and consumed by the spotted seer is sufficient enough to sustain the normal growth of the fish, and that the process of normal food consumption and growth goea on in spite of severel interspacific competition. The K-lines reveal that the general level of gross growth efficiency is within the noma1 range of 0.25 to 0.75. The Paloheimo-Dickie weight growth model is not valid for the apotted seer, owing to the slope of the T-line being significantly different from the value describing the relation between metabolism and body weight under normal non-stress conditions.



Date : 30-12-1998