The traditional theory of cetacean evolution was that cetaceans were related to the mesonychids. Beluga whales are the only cetacean being common around the peninsula. Cetacean bycatch is increasing in intensity and frequency. Dusky dolphins may fall victim to the small cetacean fisheries of Peru and Chile. The term cetacean (for whale) derives from "cetus". White shark predation on other species of small cetacean has also been observed. Risso's dolphins are one of the most commonly observed cetacean along east coasts of Taiwan. The cetacean ear has specific adaptations to the marine environment. Cook Strait is an important habitat for many cetacean species. Three subspecies are recognised in Rice's 1998 survey of cetacean taxonomy. There is heavy debate as to whether cetacean vocalizations can constitute a language. The Delphinidae are the most diverse of the cetacean families, with numerous variations between species. The Japanese Institute of Cetacean Research disputes Sea Shepherd's statements. This indicates that "B. ceti" is common amongst cetacean families and populations. A stranding is when a cetacean leaves the water to lie on a beach.