Dear colleagues As a part of one of the long-term studies of killer whales in the North Atlantic we have for years been trying to explain the apparent ecological and behavioral differences between the whales in the eastern North Atlantic, off the Norwegian coast, and the whales in the Pacific Northwest. Parts of the explanation might be related to the catastrophic events in these waters when the North Atlantic spring-spawning herring stock collapsed in the late 1960s and the compensatory high-intensity cull of killer whales in Feb-March in 1969 and 1970. I have been searching the literature for years (so far without luck) to try to find similar events in other species, where a mammal population has been exposed to catastrophic events removing their prey base, or from radical culls, and where there are some data allowing us to look at some of the consequences, both in terms of reproduction, social ecology and/or feeding ecology. Any bit of information will be highly appreciated. Regards, - - - - - - - - - - - - - - - - - - - - Dag Vongraven Senior adviser Norwegian Polar Institute Fram Center N-9296 Tromsø, Norway Tlf +4777750638 Faks +4777750501 Mobil +4792059526