Hawaiian Islands False Killer Whale
The false killer whale is a large member of the dolphin family found in tropical oceans worldwide. The Main Hawaiian Islands (MHI) insular population is a small, discrete group of false killer whales that lives exclusively in nearshore waters around the Main Hawaiian islands and is listed as endangered. The number of whales in this population has declined in recent decades likely due primarily to interactions with fisheries.
False killer whales are highly social animals that form social “clusters” of individuals that tend to move in unison and maintain close associations with one another. Within clusters, animals form smaller hunting groups that change size constantly as cluster members join and leave them. The species tight-knit social structure serves to maintain populations as discrete reproductive groups within relatively fixed home ranges. At least three geographically overlapping populations of false killer whales occur in Hawaii. The MHI insular population consists of three social clusters that occur primarily within about 50 nautical miles of the MHI, but individual members have been tracked with telemetry tags to waters as far as 75 nautical miles from shore. The other two populations of false killer whales found in Hawaii waters consist of (1) a pelagic population that occurs in offshore waters from about 20 nautical miles of shore to beyond the 200 nautical mile limit of the U.S. exclusive economic zone (EEZ), and (2) a Northwestern Hawaiian Islands Insular population that lives within about 50 nautical miles of the chain’s small islets from Gardner Pinnacles (midway along the chain) to western Oahu in the MHI.
Aerial surveys, photo-identification, satellite telemetry, and genetic studies have made the MHI insular population the world’s most thoroughly studied false killer whale population. Based on photo-identification studies, its current size is estimated to number about 150 whales. This is believed to be significantly smaller than its size in the late 1980s when aerial surveys around the MHI sighted individual groups of false killer whales in excess of 300 whales. The major known threat for this and other false killer whale populations in Hawaii is interactions with fisheries. Such interactions can cause injury and death when whales become hooked or entangled on fishing lines, particularly longlines, as they try to take bait or caught fish from deployed gear.
The National Marine Fisheries Service (NMFS) is responsible for conserving false killer whales. In September 2009, the Natural Resources Defense Council petitioned the agency to list the MHI insular population of false killer whales as endangered under the Endangered Species Act (ESA). After considering the petition and concluding that the population qualified as a distinct population segment under the ESA, NMFS listed it as endangered on November 28, 2012.
Although such listings require that the agency identify critical habitat for the species, as of November 2016 NMFS had not designated any critical habitat areas. As part of the population’s listing process, NMFS announced on October 2, 2013 its intent to prepare a recovery plan to guide future research and management recovery activities. To gather information and ideas on actions to include in the plan, NMFS convened a recovery planning workshop for MHI insular false killer whales on 25-28 October 2016 and expected to circulate a draft plan for public comment in 2017.
What the Commission Is Doing
In 2009, the Commission recommended and supported actions by NMFS to list MHI insular population of false killer whales as endangered. In part, we provided support for a study to compile and analyze related biological information. To reduce threats due to fishery interactions to the MHI insular population and other false killer whale populations in Hawaii, we also recommended that NMFS establish a Hawaiian False Killer Whale Take Reduction Team. In February 2010, NMFS established the team and charged it with preparing a plan to minimize false killer whale interactions with the Hawaii longline fisheries for tuna and swordfish. A representative of the Commission has participated on the team since inception. In November 2012, the NMFS also listed the population as endangered.
In July 2010, the team developed a recommended take reduction plan and provided it to the NMFS. The plan focuses primarily on the Hawaii pelagic population of false killer whales because most fishery interactions with this species in Hawaii have occurred within its range. However, some interactions also occurred within the range of the insular population. Therefore, the plan also includes important measures for its protection as well. Since 2010, the team has met several times to review information on plan implementation. Its most recent meeting was held in on April 29 – May 1, 2015. A representative of the Commission participated.
To learn more, see current conservation efforts for Hawaiian false killer whales.
Commission Reports and Publications
See the false killer whale sections in chapters on Species of Special Concern in past Annual Reports to Congress.
Report prepared for the Marine Mammal Commission:
Baird, Robin W. 2009. A review of false killer whales in Hawaiian waters: biology, status and risk factors.
|Letter Date||Letter Description|
|July 10, 2014|
|February 4, 2010|
|February 17, 2010|
|October 1, 2012|
Interactions with fisheries are the primary threat to false killer whales. They are often attracted to fishing vessels where they take or “depredate” bait and hooked fish. As a consequence, they are sometimes caught on hooks or entangled in fishing lines. Such fisheries interactions with Hawaii-based longline fisheries have become a significant conservation issue for false killer whales. Learn more.
Current Conservation Efforts
In 2015, the Hawaiian False Killer Whale Take Reduction Team met to review new information on the effectiveness of the take reduction plan in mitigating fishery interactions with false killer whales in Hawaii. Learn more.