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Diet of the Brandt's Cormorant (Phalacrocorax penicillatus) breeding population on Alcatraz Island, California, USA was determined for 2014-2016 using two sampling methods. Regurgitated pellets and complete nests were collected, once all chicks had left colonies, to reduce disturbance to nesting birds. Results identified 25 prey taxa including 23 teleost fishes and two cephalopods. Diet was dominated by northern anchovy (Engraulis mordax) and speckled sanddab (Citharichthys stigmaeus), with plainfin midshipman (Porichthys notatus), sole spp. (Pleuronectidae), and sculpin spp. (Cottidae) rounding out the top five abundant species. Comparison of diet by sample type yielded similar results in terms of prey species composition, but total diet differed between the two samples due to rare prey items being more prevalent in nest samples. Determining cormorant diet using a combination of pellet and nest samples is a novel approach with the potential to provide a better representation of prey consumed during the full breeding period (up to 6 months for cormorants), and similar methods may be informative for other seabirds that produce pellets. In contrast, diet determined from pellets alone may only represent a short time period just prior to collection, as pellets are often blown away by strong winds or disintegrate through trampling and/or exposure to the elements in open seabird breeding colonies. [ABSTRACT FROM AUTHOR]

Feeding studies can provide researchers with important insights towards understanding potential fishery impacts on marine systems. Raja rhina is one of the most common elasmobranch species landed in central and northern California demersal fisheries, yet life history information is extremely limited for this species and aspects of its diet are unknown. Specimens of R. rhina were collected between September, 2002 and August, 2003 from fisheries-independent trawl surveys. Percent Index of Relative Importance values indicated that the five most important prey items in 618 stomachs of R. rhina were unidentified teleosts (31.6% IRI), unidentified shrimps (19.6% IRI), unidentified euphausiids (10.9% IRI), Crangonidae (7.4% IRI), and Neocrangon resima (6.0% IRI). There were significant dietary shifts with increasing skate total length and with increasing depths. Smaller skates ate small crustaceans and larger skates ate larger fishes and cephalopods. With increasing depths, diet included bentho-pelagic teleosts and more cephalopods and euphausiids. The findings of this study are consistent with previous researchers that report similar diet shifts in skate species with size and depth. [ABSTRACT FROM AUTHOR]

The big ( Raja binoculata), California ( R. inornata), longnose ( R. rhina), and sandpaper ( Bathyraja kincaidii), skates are commonly found on soft-bottom regions of the central California continental shelf and upper slope. The feeding ecology of this assemblage was compared to evaluate the degree of trophic separation among species, based on the results of previous species-specific diet studies. Specimens were collected from fishery independent trawl surveys conducted during September 2002–March 2003 at depths of 9–536 m. Using single and compound measures, diet composition of small (≤60 cm TL) and large (>60 cm TL) individuals were compared within continental shelf (≤200 m) and slope (>200 m) regions using traditional, multivariate, and novel techniques. Diet compositions within size classes were similar in both regions. Diet compositions between size classes generally differed, however, with fishes more important and crustaceans (especially shrimps and euphausiids) less important in the diets of large individuals. Crabs contributed substantially to skate diet compositions on the shelf, but were uncommon prey items at deeper depths, probably because of their relative scarcity in slope waters. Conversely, cephalopods were common prey items at slope depths, but were rarely ingested at shelf depths. The studied skate assemblage appears to consist primarily of generalist crustacean and fish predators that exhibit high dietary overlap at similar sizes. It is possible that resource competition among skates and groundfish species has been reduced because of considerable recent declines in the biomass of upper trophic level groundfishes. Skates may therefore play important roles in contemporary benthic food web dynamics off central California. [ABSTRACT FROM AUTHOR]