PREDATOR STOMACHS AS SAMPLING TOOLS FOR PREY DISTRIBUTION, ATLANTIC COD (GADUS-MORHUA) AND CAPELIN (MALLOTUS-VILLOSUS)

We demonstrate a direct relationship between the amount of prey (cape in, Mallotus villosus) in its predators' stomachs (Atlantic cod, Gadus morhua) and the biomass of the prey in the same localities. The relat ionship at a local scale implies that predator stomach contents can be used to estimate prey distribution. There is no evidence for either ( 1) a negative effect of local predator abundance on stomach contents ( expected if local prey depletion and/or feeding interference occurs wh en predator density is high) or (2) a negative effect of the amount of other food in cod stomachs on the amount of capelin in the stomachs ( expected if prey switching occurs). There is a negative effect of bott om depth on amount of capelin in cod stomachs as expected, since capel in are pelagic and cod are primarily bottom-dwelling, resulting in les s vertical overlap between the species in deep water. This type of ana lysis may be useful in other predator-prey systems. Simultaneous stoma ch samples and independent biomass estimates of the prey are required, but once the model is built, it permits estimation of prey distributi on in places and times when no direct survey of the prey can be done.