Food habits of the sandpaper skate, Bathyraja kincaidii (Garman, 1908) off central California: seasonal variation in diet linked to oceanographic conditions |
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Authors: | Christopher S Rinewalt David A Ebert Gregor M Cailliet |
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Institution: | (1) Pacific Shark Research Center, Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039, USA |
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Abstract: | The stomachs of 130 sandpaper skates, Bathyraja kincaidii (Garman, 1908), were sampled from off central California to determine their diet composition. The overall diet was dominated
by euphausiids, but shrimps, polychaetes and squids were also important secondary prey. A three-factor MANOVA demonstrated
significant differences in the diet by sex, maturity status and oceanographic season using numeric and gravimetric measures
of importance for the major prey categories. These three main factors explained more variation in diet than interactions between
the factors, and season explained the most variance overall. A detailed analysis of the seasonal variation among the prey
categories indicated that abundance changes in the most important prey, euphausiids, were coupled with seasonal changes in
the importance of other prey. When upwelling occurred and productivity was great (Upwelling and Oceanic seasons), euphausiids
were likely highly abundant in the study area and were the most important prey for B. kincaidii. As productivity declined (Davidson Current season), euphausiids appeared to decrease in abundance and B. kincaidii switched to secondary prey. At that time, gammarid amphipods and shrimps became the most important prey items and polychaetes,
mysids and euphausiids were secondary. |
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Keywords: | Arhynchobatidae MANOVA Euphausiids Gammarid amphipods |
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