Primary Growth Increments in Otoliths of Six Tropical Myctophid Species

Abstract

AbstractThe otoliths of six species of myctophids belonging to the genera Benthosema, Diaphus, Myctophum, Lampanyctus, and Symbolophorus were collected in the western Arabian Sea in 1979 and revealed primary growth increments; the readability of the otoliths, however, varied considerably among the six species. The hypothesis of a daily deposition rate of the increments could not be verified, but strong circumstantial evidence for this was put forward. Under this hypothesis, power curves were fitted to the length at age data, yielding length = 0.59 Age0.77 and length = 0.69 Age0.79 for B. pterotum in the Gulf of Oman and the Gulf of Aden respectively, and length = 2.65 Age0.53 for B. fibulatum. A prominent check in the otoliths is suggested to be caused by metamorphosis.