ASSIMILATION EFFICIENCY OF CAPTIVE RINGED SEALS (PHOCA-HISPIDA) FED DIFFERENT DIETS

Food type or quality can influence assimilation efficiency (AE). AE (d igestibility of dry matter) of two captive adult ringed seals (Phoca h ispida one male, one female) was estimated for five prey types. In tri als, each of > 8 days duration, the seals were fed redfish (Sebastes s pp.), capelin (Mallotus villosus), Arctic cod (Boreogadus saida), Atla ntic herring (Clupea harengus) and a mixture of herring and shrimp (Pa ndahus borealis). Prey were marked so that faecal samples could be mat ched to individual seals, and AE was estimated by the relative concent ration of Mn2+ in food and faeces. AE was high but varied among the pr ey species (redfish 83%; capelin 87%: Arctic cod 88%; herring 94%; her ring/Pandalus mixture 92%). There was a weak, positive relationship be tween AE and prey lipid content or energy density, but a negative rela tionship with inorganic content. AE was lower than expected for capeli n with high fat content. AE was not correlated with meal mass? number of fish in a meal, or seal mass. AE did not differ between the two sea ls.