About Globicephala macrorhynchus Gray, 1846
Globicephala macrorhynchus, commonly known as the short-finned pilot whale, has a base coloration ranging from black to dark gray or brown. It has a thick tail stock, a fluke with sharply pointed tips, a bulbous head, and a broad, sickle-shaped dorsal fin. Typical coloration includes light gray to white markings: a saddle patch behind the dorsal fin, a light gray or white anchor-shaped patch under the chin and belly, and a blaze marking behind the eye. These physical traits can vary between populations. For example, two distinct forms are recorded off the Pacific coast of central Japan. The larger Shiho morphotype has females measuring 4 to 5 m (13 to 16 ft) and males measuring 5 to 6 m (16 to 20 ft), with a white dorsal patch and a round melon (the bulbous forehead structure). The smaller Naisa type has females measuring 3 to 4 m (10 to 13 ft) and males measuring 4 to 5 m (13 to 16 ft), with a characteristic flattened or squarish melon and a darker, indistinct saddle patch. The maximum recorded size for the species is 7.2 m (24 ft) in length and up to 4,000 kg (8,800 lb) in weight, making it the third-largest species of oceanic dolphin, ranking behind only the orca and the long-finned pilot whale. Newborn short-finned pilot whales measure 1.4 to 1.9 m (4 ft 7 in to 6 ft 3 in) in length and weigh around 60 kg (130 lb). Short-finned pilot whales are often difficult to distinguish from long-finned pilot whales. As their common name suggests, the flippers of short-finned pilot whales are shorter than those of long-finned pilot whales, measuring around one-sixth of the animal's total body length. Short-finned pilot whales also have fewer teeth, with 7 to 9 teeth in each row, and a shorter, broader rostrum (snout) where the premaxilla bone covers more of the maxilla bone. Both species exhibit sexual dimorphism and have similar lifespans: around 45 years for males and 60 years for females, and long-finned pilot whales are generally larger overall than short-finned pilot whales. The two species have limited geographic overlap across the world: long-finned pilot whales live in cooler temperate waters, while short-finned pilot whales are distributed mostly in tropical and subtropical regions. Short-finned pilot whales occur in both coastal and pelagic waters across temperate and tropical regions of the Indian, Atlantic, and Pacific Oceans. Information on spatial habitat use by short-finned pilot whales in the northwest Atlantic is limited, but the species is thought to range from the southern end of Georges Bank into the tropics, overlapping with the range of long-finned pilot whales along the mid-Atlantic shelf break between Delaware and Georges Bank. Off the coast of Japan, the distributions of the Shiho and Naisa types are well-documented and largely nonoverlapping: Naisa-type individuals inhabit the warm-temperate waters of the Kuroshio Current, while Shiho-type individuals inhabit the cold-temperate waters of the Oyashio Current. Some evidence suggests these two populations may even be separate subspecies, based on differences in morphology, mitochondrial DNA, and breeding seasons. Outside of Japan, the Naisa-type is found in southeast Asia, the Indian Ocean, and Hawaii, while the Shiho-type can be found in the California Current and off Peru. Pilot whales display strong natal philopatry. Many populations remain year-round in locations including Hawaii, the U.S. and British Virgin Islands, the Madeira Islands, and parts of California, though some populations migrate to follow seasonal and annual fluctuations in water temperature and productivity. Short-finned pilot whales were once commonly sighted off Southern California, but disappeared from the area after the strong El Niño events of 1982 and 1983. Since that time, they have only been encountered infrequently, mostly during warm-water years including 1991, 1993, 1997, 2014, and 2015. It remains unknown whether the individuals sighted more recently belong to the same population documented off Southern California before the mid-1980s, or belong to a different wide-ranging pelagic population, so the conservation status of this stock is still unknown. Short-finned pilot whales are economically important to the whale-watching industry in several parts of the world, including Madeira, Hawaii, and the Canary Islands, all of which host resident populations of the species. The effects of tourism activities on these whales have not been extensively studied, but some evidence indicates that underwater noise from whale-watching boats can significantly disrupt communication when boats are at close range. Many countries have published safe whale-watching guidelines designed to minimize the impact of human activities on the whales. In terms of reproduction, male short-finned pilot whales are polygynous, meaning they mate with multiple females at one time and throughout their lives. Pods typically contain around one mature male for every eight mature females. During mating aggregations, males temporarily leave their pods to mate with females from other pods, then return to their original pods after mating is complete. This behavior helps prevent inbreeding. Females reach sexual maturity at around 7 to 12 years of age, and produce a new calf every five to eight years, averaging 4 to 5 calves over their entire lifetime. Calves suckle from their mothers for a minimum of two years, with most continuing to suckle for five years, and some evidence indicates that females may continue lactating for up to 15 years after the birth of their last calf. Females usually stop reproducing once they reach 40 years of age, even though their maximum lifespan is over 60 years.
