Date

2007

Document Type

Master's Thesis

Degree Name

Master of Science (M.S.)

Department

Moss Landing Marine Laboratories

Abstract

Stomach contents of the sandpaper skate, Bathyraja kincaidii (Garman, 1908), were examined from a limited depth off central California and from a wider depth and area range along the eastern North Pacific (ENP). The species overall diet was dominated by euphausiids and shrimps, with polychaetes, squids, and gammarid amphipods important secondary prey. A three-factor MANOVA demonstrated significant differences in the importance of major prey categories by sex, maturity status, and oceanographic season in the central California data. These three main factors explained the greatest amount of dietary variation and season explained the most variance overall. Differences in the diet by sex, maturity status, and geographic zone of capture occurred in the ENP. Geographic zone explained the most variance in the diet, though much less than the amount explained by the central California data. A three-factor MANCOVA revealed significant differences in the oral and dental morphology of B. kincaidii due to all the main factors (sex, maturity status, and geographic zone) and their interactions among all variables measured. However, variation between the sexes explained one third of all the morphological variance. A comparison of the intra-specific differences in morphology with such differences in the diet indicated that the two were not related. I suggest that intra-specific differences in the morphology of skates are related more to mating; the extreme morphology of mature males allows them to better capture and hold females during courtship, but such differences do not satisfactorily account for differential exploitation of any prey category.

Comments

Thesis (M.S.) Division of Science and Environmental Policy. Moss Landing Marine Laboratories

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