Scientific investigations aboard the ATOLL concentrated on one of the most important food chain transitions: the linkages between the early life stages of herring ("Clupea harengus") and their principal prey, the copepods. A major hypotheses of fisheries ecologists is that the microdistribution of prey, the microturbulence of the ocean, or the retention conditions are normally not suited to allow strong year classes of fish to develop. In most years more than 99% of herring larvae do not survive. Occasionally however, physical and biotic conditions are favorable, larval survival is high, and large year-classes result. Research work at the ATOLL investigated the effects of small-scale dynamics on fish feeding and predator avoidance and their correlation to year-class strength.