 National Marine Fisheries Service (NMFS) is mandated under the Marine
Mammal Protection Act to ensure the sustainability of marine mammal
populations in the U.S.; including the impact commercial fisheries are
having on these populations. According to a study by Carretta et al.
(2006), the estimated rate of serious injury and mortality caused to false
killer whales by the U.S. long-line fishery is estimated to be greater than
the “Potential Biological Removal” (PBR) level for the population existing
within the Hawaii Exclusive Economic Zone (EEZ). The Hawaii EEZ encompasses
a 200-mile zone around the state of Hawaii. This means that if the current
population estimates for false killer whales within the EEZ are correct, the
long-line fishery is significantly impacting this small population in a
negative way and must be properly managed. This information has made false
killer whales a species of concern in Hawaii and efforts are being made to
better understand their abundance, movements, and genetics.
One study conducted a large-vessel line transect survey within the EEZ and
estimated only 236 individuals (CV=1.13) (Barlow, 2006). Another study,
using mark-recapture analyses of dorsal fin photos, estimated 123
individuals (CV=0.72) around the main Hawaiian Islands (Baird et al.,
2005).
   
Genetic analysis has shown that
false killer
whales around the main Hawaiian Islands are genetically separated from those
elsewhere in the tropical Pacific (Chivers et al., 2006). However, the
boundary between inshore and offshore populations is not yet clear. Some
individual false killer whales found inshore appear to have dorsal fin
injuries caused by interactions with long-liners. This suggests that the
inshore populations may be interacting with the long-line fishery (Baird and
Gorgone, 2005).
Collaborative efforts among researchers to photo-identify false killer
whales within the main Hawaiian Islands continues. HAMER researchers
are participating in these efforts to help understand their population size, home range, movement
patterns, and social structure.
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