Premium
Aspects of reproduction and diet of the Australian endemic skate Dipturus polyommata (Ogilby) (Elasmobranchii: Rajidae), by‐catch of a commercial prawn trawl fishery
Author(s) -
Kyne P. M.,
Courtney A. J.,
Bennett M. B.
Publication year - 2008
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.2007.01655.x
Subject(s) - biology , elasmobranchii , prawn , skate , reproduction , fishery , chondrichthyes , crustacean , predation , bycatch , zoology , fish <actinopterygii> , ecology
The Australian endemic skate Dipturus polyommata collected from by‐catch of a benthic prawn fishery off southern Queensland was examined to provide information on reproduction and diet. Morphological relationships of total length ( L T ) to disc width and L T to mass were estimated. Size at birth was estimated at c. 100–110 mm and size at first feeding at c. 105–110 mm L T . Size at 50% maturity ( L T50 and 95% CI) was 321 (305–332) and 300 (285–306) mm L T for females and males, respectively. Size at first maturity corresponded to 87·7% of observed maximum size in females (366 mm L T ) and 87·5% in males (343 mm L T ). Two females, representing 18·2% of mature females sampled in the austral winter were each carrying two egg cases. Descriptions of egg cases are given. Diet described by the index of relative importance as a percentage (% I RI ) was predominantly crustacean based with carid shrimps (53·64%) and penaeoid prawns (23·30%) the most significant prey groups. Teleosts (11·72%), gammarid amphipods (5·31%) and mysids (4·72%) were also important to the diet of the species, while a further six prey groups made only a minor contribution to diet (1·31%). An ontogenetic change was evident between the diets of immature and mature skates. Immature animals fed more extensively on carids and amphipods and mature animals on penaeoids, teleosts and mysids.