Reproductive Biology of Two Hawaiian Pelagic Carangid Fishes, the Bigeye Scad, Selar Crumenophthalmus, and the Round Scad, Decapturus Macarellus

Bigeye scad Selar crumenophthalmus and round scad Decapturus macarellus were sampled from commercial fishery catches in Hawaii. Size at maturity of bigeye scad is ≤200 mm standard length. Spawning season is from April through September or October. Round scad mature at about 245 mm SL, and spawning occurs from April through August. Both species appear to spawn sometime between dawn and dusk. For bigeye scad, the frequency of postovulatory follicles indicates that females spawn every three days; batch costs average about 3% of body weight. Postovulatory follicles were found very infrequently in round scad. Mean batch fecundities of bigeye scad and round scad were 92,000 and 136,000, respectively; relative fecundity of bigeye scad averaged about twice that of round scad. Fecundities of bigeye scad and round scad are similar to those reported for other tropical carangids. Annual reproductive output appears to be higher in bigeye scad and round scad than in the temperate Trachurus spp., but spawning frequency of the latter may have been underestimated by most previous studies.