Gastrointestinal evacuation of particulate matter in polar cod Boreogadus saida

Abstract

Gastrointestinal evacuation of inert particles was monitored in the polar cod Boreogadus saida (Lepechin), held at a temperature of 0.5°C. Fish (31.8 g ± 0.8 SD) were fed a moist diet, based on natural prey items, containing a particulate marker. Evacuation of marker from the gastrointestinal tract started 48 h after ingestion of a meal. The average time needed to evacuate 50% of the marker was estimated to be 132 h, whereas the total evacuation time was approximately 400 h. This may indicate that the polar cod does not feed on a daily basis at temperatures close to zero because of the prolonged time needed to evacuate meals. This work provides a methodological basis for studies of feeding and growth in polar cod using X-radiography.