The story of the Hawaiian false killer whales

I was going to write an entry introducing you to the False Killer Whale since I'm guessing you may not have heard of it, but Andrew has already done a fine job of that. Since the distribution of the entire species spans around the world, however, you may be wondering why we are concerned about one population - and this population in particular.

It's largely because they have decided to make Hawaii their home. While the rest of the species is found far from land in deep waters, this population of false killer whales has taken up year-round residence just off shore from the Hawaiian archipelago. Who could blame them, really? Their physical and genetic separation from other false killer whales points to the uniqueness of this population, but it also highlights the ecological and evolutionary significance of the Hawaiian Islands.

One of the most isolated island chains in the world, Hawaii is also home to an unusually large number of ‘endemics' - organisms that are not found anywhere else. While endemism is considered uncommon in wide-ranging cetaceans (whales, dophins and porpoises), several other species also have unique populations in and around the Hawaiian Islands. Bryde's whales and short-finned pilot whales, for example, are genetically distinct from animals sampled in the surrounding pelagic waters. Spinner dolphins, rough-toothed dolphins and bottlenose dolphins also appear to have differentiated island populations in the Hawaiian archipelago. This clearly tells us that Hawaii is an ecologically rich and evolutionarily unusual area for marine life.

In the case of the false killer whale, their unique population is also telling us another part of the story. Fin disfigurements tell us that this small population is directly affected by fisheries in the area while declines in the size or number of some of their main prey species (bigeye tuna, yellowfin tuna and mahi mahi) indicate an indirect effect of the fisheries. Tissue samples tell us that one third of the population contains levels of PCBs above the safety recommendations identified for other species, indicating that Hawaiian false killer whales may suffer health effects from pollutant exposure.

Considering these factors are likely to affect other marine animals in the area and knowing the vast array of unique marine life found around the islands, the story of the Hawaiian false killer whales is an important one to hear. By addressing the threats to this rare population, we may be better able to ensure the persistence of not only the Hawaiian false killer whale, but the persistence of one of the most biologically important marine areas on earth.