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Vol. 53 - Alaska Resources Library and Information Services

Vol. 53 - Alaska Resources Library and Information Services

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DISCUSSION<br />

IMMUNOASSAY<br />

The immunological examination of stomach contents as applied here<br />

provided evidence that juvenile king crab consume prey items overlooked by<br />

conventional visual examination of gut contents <strong>and</strong> that these overlooked<br />

prey were soft-bodied, readily-digested organisms. As expected, the value<br />

of the immunoassay was greatest for the smallest juvenile king crab.<br />

The immunoassay suffered some lack of sensitivity apparently due to<br />

low gut residence times of antigenic determinants. Because of the rapid<br />

breakdown of antigenic determinants in crab stomachs, the extent to which<br />

the smallest juvenile crabs depend on soft bodied macro <strong>and</strong> meiofaunal<br />

prey could well be underestimated here.<br />

Further use of this immunoassay for king crabs <strong>and</strong> other crustaceans<br />

should be enhanced by experimental determination of gut residence times of<br />

the antigenic determinants. Particularly important would be the<br />

determination whether there is substantial enough variation in gut<br />

residence times of antigenic determinants with prey type to be a<br />

significant source of bias. If prey types do vary substantially in the<br />

gut residence times of their antigenic determinants, then correction of<br />

dietary composition determined by immunoassay would follow the procedures<br />

used here for correction of dietary composition determined by visual<br />

examination.<br />

Replacing the algorithm for eliminating reactions that may be<br />

cross-reactions with the retesting for lines of identity after initial<br />

screenings proved to be a better method for juvenile king crab although<br />

more time consuming. Retesting for lines of identity reduces potential<br />

loss of information due to the conservative nature of the algorithm. More<br />

study is needed to develop an improved experimental approach to the<br />

elimination of cross reactions.<br />

Other experimental studies to refine the immunoassay would include the<br />

following: time studies of the decay of mixtures of antigenic determinants<br />

using prey with no cross reactions; feeding experiments to determine the<br />

effects of digestive processes on changes in the antigenic determinants;<br />

241

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