Biology Of Skates (developments In Environmental Biology Of Fishes)

Skates have become a concern in recent years due to the preponderance of these elasmobranchs that are caught as bycatch or as a directed fishery. This has raised concern because skates have life history characteristics that may make them vulnerable to over-exploitation. It was due to this concern that prompted Drs. David Ebert and James Sulikowski to organize an international symposium on the "Biology of Skates". The aims and goals of the symposium were to bring together an international group of researchers to meet, discuss, perhaps develop collaborations, and present their most recent findings. The symposium was held over two days, on 13-14 July, 2006, in conjunction with the 22 nd annual meeting of the American Elasmobranch Society in New Orleans, LA. A total of 31 authors from four countries contributed 16 papers that appear in this volume. The papers are broadly arranged into four separate categories: systematics and biogeography, diet and feeding ecology, reproductive biology, and age and growth. This is the first dedicated book on the biology of skates. We hope that readers will find this volume of interest and that it helps encourage and stimulate future research into these fascinating fishes. Front Matter....Pages I-VI Preface: Biology of skates....Pages 1-4 Biodiversity and systematics of skates (Chondrichthyes: Rajiformes: Rajoidei)....Pages 5-18 Southern African skate biodiversity and distribution....Pages 19-39 Food habits of the sandpaper skate, Bathyraja kincaidii (Garman, 1908) off central California: seasonal variation in diet linked to oceanographic conditions....Pages 41-57 Food habits of the longnose skate, Raja rhina (Jordan and Gilbert, 1880), in central California waters....Pages 59-73 Dietary comparisons of six skate species (Rajidae) in south-eastern Australian waters....Pages 75-90 Comparative feeding ecology of four sympatric skate species off central California, USA....Pages 91-114 Standardized diet compositions and trophic levels of skates (Chondrichthyes: Rajiformes: Rajoidei)....Pages 115-131 Normal embryonic development in the clearnose skate, Raja eglanteria , with experimental observations on artificial insemination....Pages 133-149 Endocrinological investigation into the reproductive cycles of two sympatric skate species, Malacoraja senta and Amblyraja radiata , in the western Gulf of Maine....Pages 151-159 Morphological variation in the electric organ of the little skate ( Leucoraja erinacea ) and its possible role in communication during courtship....Pages 161-169 Reproductive biology of Rioraja agassizi from the coastal southwestern Atlantic ecosystem between northern Uruguay (34°S) and northern Argentina (42°S)....Pages 171-178 Profiling plasma steroid hormones: a non-lethal approach for the study of skate reproductive biology and its potential use in conservation management....Pages 179-186 Age and growth estimates for the smooth skate, Malacoraja senta , in the Gulf of Maine....Pages 187-202 Age, growth, maturity, and mortality of the Alaska skate, Bathyraja parmifera , in the eastern Bering Sea....Pages 203-217 Age and growth of the roughtail skate Bathyraja trachura (Gilbert 1892) from the eastern North Pacific....Pages 219-230 Age and growth of big skate ( Raja binoculata ) and longnose skate ( R. rhina ) in the Gulf of Alaska....Pages 231-243