In Hawaiian waters, dorsal fin shapes show a lot of variability, often caused by injury from fishery interactions.Īdult females reach lengths of 16 feet, while adult males are almost 20 feet long. The dorsal fin is located in the middle of the back and generally curves backward. The pectoral fins or flippers have a distinct central hump creating an S-shape along the outer edge. The front of an adult male’s head hangs over the lower jaw to a greater extent than in females and is flattened in older males. They have a small conical head without a beak. The species is large and slender, and males are slightly larger than females. They are dark gray, often appearing black on all but a small part of their ventral (underside) surface, which is lighter between the pectoral fins running from the throat down to the belly. Learn more about the three populations of false killer whales in Hawaiʻi Protected Statusįalse killer whales are large members of the dolphin family. Current population abundance estimates for all stocks (Northwestern Hawaiian Islands, the northern Gulf of Mexico, and the western North Atlantic) can be found in the latest marine mammal stock assessment reports. The Northwestern Hawaiian Islands, northern Gulf of Mexico, and western North Atlantic stocks (populations) of false killer whales are not as well-studied. There have been only three large-scale surveys in Hawaiian waters, and changes in survey design (intended to provide more precise estimates given the social structure and behavior of false killer whales) make it difficult to determine trends in abundance for this pelagic population. Their historical population size is also unknown, though interactions with longline fisheries are known to have killed or seriously injured animals in this population since at least the late 1990s. Sighting data collected from ship-based, line-transect surveys conducted by NOAA Fisheries within the central Pacific Ocean between 1986 to 2017 uses a model-based approach to estimate the Hawaiʻi pelagic population of false killer whales to be roughly 2,115 individuals. Annual variability in survey efforts within the range of the main Hawaiian Islands insular false killer whale make it difficult to assess population trends, so it’s unknown whether the population has continued to decline, recently stabilized, or recently increased. The cause of this decline is unknown, but it’s thought to be partially due to interactions with fisheries, especially before 1990 when longline fishing was more common in the nearshore waters of Hawaiʻi. Aerial survey sightings since then suggest that the main Hawaiian Islands insular false killer whale population declined at an average rate of 9 percent per year through at least the early 2000s. The historical population size is unknown, though spotter planes in the late 1980s observed large aggregations of 350 to 400 whales in a single area. The endangered main Hawaiian Islands insular false killer whale distinct population segment (DPS) is estimated to number less than 200. The broad pelagic distribution of most false killer whale populations makes it difficult to estimate the global population size of this species. Our scientists and partners use a variety of innovative techniques to study and protect this species. NOAA Fisheries is committed to conserving and protecting false killer whales. This stock is also listed as depleted under the Marine Mammal Protection Act (MMPA). It is the only false killer whale population protected under the ESA. This is especially a concern for false killer whales that interact with the Hawaiʻi longline fishery.ĭue to its very small population size (less than 200 individuals) and population decline until at least the early 2000s, the main Hawaiian Islands insular false killer whale distinct population segment (DPS) is listed as endangered under the Endangered Species Act. False killer whales are known to depredate (take fish and bait off of fishing lines), which can lead to hooking and/or entanglement. The false killer whale’s entire body is black or dark gray, although lighter areas may occur ventrally (on its underside) between the flippers or on the sides of the head.įishery interactions are one of the main threats facing this species. False killer whales are social animals found globally in all tropical and subtropical oceans and generally in deep offshore waters.
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