Due to its large range and population, currently estimated at over 50,000, of which around 45,000 reside in the tropical east Pacific, the melon-headed whale is not thought to be threatened with extinction. This species is relatively common in parts of its range, in particular in the Philippine Sea, which is perhaps the species’ stronghold. However, at present there is no information available on population trends, and as its fish prey is likely decreasing from over-fishing, this whale may actually be in decline (1).
The melon-headed whale is taken in a number of small net and harpoon cetacean fisheries, including in St Vincent, the Philippines and Taiwan, while it is also killed in the annual dolphin drive at Taiji, Japan, although the number of whales killed in these fisheries and its impact on the population is unknown (1). A small number of whales are also killed as bycatch in nets for tuna, although this is likely to be a somewhat smaller threat compared to direct fishing (1) (5).
Mass strandings of the melon-headed whale are commonly reported which, although the cause of this is unknown, may be due to outbreaks of parasites or a panic response in the school when a few members accidentally become stranded (5). However, one incident on the Hawaiian island of Kauai, when between 150 and 200 whales become stranded on a bay, may be attributed to U.S. Navy training involving the use of sonar (1) (8). It is also possible that the use of sonar and seismic exploration can kill whales by causing gas bubble disease (9).
The melon-headed whale could also become threatened by climate change, as rising sea levels and increased surface sea temperatures may potentially alter the abundance and distribution of its prey species (10).