New Distributional Record of Greater Amberjack Seriola dumerili (Risso, 1810) (Perciformes: Carrangidae) from the Eastern Arabian Sea, India

Background: The fishes of the family Carangidae forms one of the largest families of bony fishes, representing about 140 species, widely distributed in all tropical and temperate marine waters of the world. In recent past, fishes of this family are exhibiting new geographical distribution which could be attributed to climatic variability. Methods: The specimens were collected from multiday trawl boats operated along Karnataka coast. Morphometric and meristic characteristics together with genetic analysis using DNA bar coding was used to validate the identity of the specimen. Spatial distribution map of the species in Indian Ocean was generated using the information from the present study and available literature. Result: The morphometric and meristic characteristics of the specimens of greater amberjack, Seriola dumerili collected during the study were comparable with the previous investigations. The phylogenetic tree constructed using sequences of COI (MW974826 and MW974827) of the Seriola species showed distinct clustering among species with significant bootstrap values confirming the identity to the extent of 99% with the sequences of Seriola dumerili deposited in NCBI GenBank. This study confirms the first distributional record of Seriola dumerili from the eastern Arabian Sea.

First report on the diet and reproductive biology of red-toothed triggerfish Odonus niger (Ruppell, 1836) from the south-eastern Arabian Sea

The feeding habits and reproductive biology of red-toothed triggerfish Odonus niger (Ruppell, 1836) was analysed from 449 specimens collected from the Karnataka coast of the south-eastern Arabian Sea. Of the total stomachs examined, only 54 (12%) were empty and 395 contained food remains. The diet comprised crustacean remains (48.0%), zooplankton (21.4%), algae (16.5%), fish remains (6.1%) and cephalopod remains (5.3%) along with partially digested matter (2.3%) and detritus (0.4%). The species was found to be a generalist feeder and an omnivore. The overall sex ratio between males and females (1: 0.44) was significantly (P < 0.05) different. Histological examination of the ovaries indicated asynchronous ovarian development in females, with males maturing earlier than females. The gonadosomatic index (GSI) patterns of males and females, and the presence of ripe ovaries and spermatozoids suggested that April–May is the peak spawning period. The absolute and relative fecundity estimates ranged from 16,464–312,420 eggs and 251–2812 eggs g−1 respectively. Fecundity was positively correlated with total length and body weight. The biological information on diet composition and reproductive traits provided for the first time in this study can facilitate conservation, management and sustainable exploitation of this species in the study area.