Biology of Skates

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.

Preface: Biology of skates.- Biodiversity and systematics of skates (Chondrichthyes: Rajiformes: Rajoidei).- Southern African skate biodiversity and distribution.- Food habits of the sandpaper skate, Bathyraja kincaidii (Garman, 1908) off central California: seasonal variation in diet linked to oceanographic conditions.- Food habits of the longnose skate, Raja rhina (Jordan and Gilbert, 1880), in central California waters.- Dietary comparisons of six skate species (Rajidae) in south-eastern Australian waters.- Comparative feeding ecology of four sympatric skate species off central California, USA.- Standardized diet compositions and trophic levels of skates (Chondrichthyes: Rajiformes: Rajoidei).- Normal embryonic development in the clearnose skate, Raja eglanteria, with experimental observations on artificial insemination.- Endocrinological investigation into the reproductive cycles of two sympatric skate species, Malacoraja senta and Amblyraja radiata, in the western Gulf of Maine.- Morphological variation in the electric organ of the little skate (Leucoraja erinacea) and its possible role in communication during courtship.- Reproductive biology of Rioraja agassizi from the coastal southwestern Atlantic ecosystem between northern Uruguay (34°S) and northern Argentina (42°S).- Profiling plasma steroid hormones: a non-lethal approach for the study of skate reproductive biology and its potential use in conservation management.- Age and growth estimates for the smooth skate, Malacoraja senta, in the Gulf of Maine.- Age, growth, maturity, and mortality of the Alaska skate, Bathyraja parmifera, in the eastern Bering Sea.- Age and growth of the roughtail skate Bathyraja trachura (Gilbert 1892) from the eastern North Pacific.- Age and growth of big skate (Raja binoculata)and longnose skate (R. rhina) in the Gulf of Alaska.