Publication
Reproductive characteristics of Ratabulus diversidens and Ambiserrula jugosa (Pisces: Platycephalidae) from continental shelf waters of south-eastern Australia
Publisher:
Cambridge University Press (CUP)
Date:
06-2021
DOI:
10.1017/S0025315421000540
Abstract: The reproductive characteristics of co-occurring freespine flathead, Ratabulus ersidens , and mud flathead, Ambiserrula jugosa , that interact with fisheries across continental shelf waters of eastern Australia were examined. S les were collected across three depth strata and two locations on a monthly basis over two years. Males of both species matured younger and at smaller total lengths (TL) than females. Estimated TL and age (years) at maturity (L 50 and A 50 , respectively) of R. ersidens also varied between locations, but differences were not related to differential growth. Although some mature in iduals of both species occurred year-round, they were most prevalent and gonadosomatic indices greatest, between the austral spring and autumn. Mature R. ersidens almost exclusively occurred in deeper offshore waters, whereas the opposite was evident for A. jugosa . Both species displayed asynchronous oocyte development, and were thus considered capable of spawning more than once throughout each spawning season. Potential batch fecundity was positively related to TL for R. ersidens , but not A. jugosa , possibly due to the small size of the latter species. The sex ratios for R. ersidens varied between locations and length categories, and like A. jugosa the larger categories were skewed towards females, a result of ergent growth between sexes. Macroscopic and microscopic evidence indicated both species were gonochoristic. The data provide new information for fisheries management consideration and contribute to the data-poor international knowledge base of platycephalid biology.