Gonadal Assessment of Picnic Sea Bream Acanthopagrusberda (Forsskål 1775), a Potential Aquaculture Candidatefor Indian Waters

Gonadal assessment of Acanthopagrus berda (Forsskal 1775), a commercially and recreationally important fish from Indian waters, was studied by collecting 250 fishes from the Korapuzha estuary, Calicut, Kerala using cast net during December 2015 to January 2016. External morphology of the gonads reveals that A. berda is bisexual (with ovo-testis) in nature with the ovarian lobe in the mid-dorsal region of the abdominal cavity and the testicular lobe as a band along the ventro-lateral wall with a major portion running along the extreme posterior region of the gonad. Males were dominant in lower length classes (17–23 cm) while females dominated in upper length classes (24–43 cm), confirming protandrous hermaphroditism in the species. Gonado-somatic index (GSI) was significantly higher (P<0.05) for the females. Males and transitional groups were showing almost similar GSI. External morphological and histological evaluation of the gonads of A. berda during the 2-month study revealed the presence of different developmental stages such as matured testis with oozing milt, an intermediate gonad structure with an anterior thin ovary-like structure and a posterior thick testis-like morphology indicating a transitional ovo-testis, maturing ovary and matured ovary. The simultaneous availability of milt oozing males and matured females from the wild indicates the opportunity for development of captive breeding, seed production and hatchery technology for this important commercial food fish.