 Nevertheless, particularly in the early 60s, fins were killed in large numbers, with the maximum kill in 1961–62 numbering over 4,000.During their journey to and from the Antarctic, Soviet fleets had a habit of stopping in the tropics to hunt whales, which was entirely illegal (despite a small number of sperm whales permissible north of the Antarctic).The tropical Indian Ocean was particularly hard hit by southbound Soviet whalers, and during the season 1966–67 the non-migratory Arabian humpback population and populations of pygmy blue whales in the northern Indian Ocean were decimated by the "Sovetskaya Ukraina" fleet.