- Scientific name: Physeter macrocephalus
- Species of Greatest Conservation Need (MA State Wildlife Action Plan)
- Endangered (MA Endangered Species Act)
- Endangered (US Endangered Species Act)
Description
The sperm whale is the largest of the toothed whales. They display a significant degree of sexual dimorphism, with adult males being about 1.5 times longer and 3 times heavier than females. Females usually reach about 11 m (36 ft) and 15 tons. Males are now rarely greater than 15 m (49 ft) but can reach about 16 m (52 ft) and 45 tons. In the early 1900s, 20 m (66-foot) bulls were sometimes taken. The sperm whale’s skin is coarse with irregular corrugations and mostly colored dark grey, though some individuals have white patches on the belly. Their head takes up approximately one-third of their total body length and has a unique single blowhole on the front left side of the head. The small dorsal fin is low enough to be unnoticeable as there is a series of lower bumps visible along the top of the tail posterior to the fin. The lower jaw is very narrow and contains 20 to 26 conical functioning teeth. Adults have a large, overhanging rostrum that contains the spermaceti organ. Sperm whales are suction feeders, so teeth are probably unnecessary for feeding as they do not break through the gums until after puberty and healthy sperm whales have been captured that do not possess any teeth. The sperm whale’s brain is the largest of any animal at 7.7 kg (17 lb) in mature males.
Life cycle and behavior
Sperm whales are a social species and often form units of adult females, their young, and juveniles of either gender, just as elephants do. These stable, long-term matriarchal units often result in separation based on age and sex. Females reach sexual maturity at around 9 years of age and produce a calf at the rate of about one every five years. There is a 14- to 16-month gestation period and females give birth to a single calf that can be up to 13 feet in length. Puberty in males is prolonged and may not be reached until the whale is 10 to 20 years old. A male may not actively participate in breeding until his late twenties. The lifespan of the sperm whale is not definitively known; however, females physically mature around 30 years of age while males mature at 50. The reproductive schedule in the western North Atlantic is unknown.
The sperm whale’s diet consists mainly of large squids, sharks, skates, and other fishes. The average dive for a sperm whale when capturing food lasts around 35 minutes, but they may dive for up to an hour and reach depths over 3,000 feet.
Population status
Despite a significant population decline caused by commercial whaling in the nineteenth and twentieth century, the sperm whale remains the most abundant of the large whale species. Current estimates range from 200,000 to 1,500,000 individuals, worldwide. As for other whales, sperm whales are threatened by ship strikes, entanglement in fishing gear, pollution, habitat degradation, predation of young by killer whales, and disturbance by anthropogenic noise.
Distribution and abundance
Sperm whales can be found in all the oceans of the world, but primarily in the higher latitudes from 45° north and south. Sperm whales generally inhabit deep water over 3,000 feet in depth and are uncommon in shallow waters. Young whales live in tropical and subtropical waters, until they migrate towards the poles sometime between the ages of 4 and 21. Thereafter, they occasionally return to warm water for breeding. Though the sperm whale’s range depends on multiple variables such as locations of food sources, breeding condition, age, and sex, there is a general seasonal north-south movement of the species.
This is a deep-water whale that is rare in state waters. They concentrate along the edge of the continental shelf. They are found from Newfoundland to the West Indies. As with fin whales, the largest males go the farthest north.
Shifts in range, elevation, or depth: From 2010 to 2017, the centroid of the sperm whale’s core range shifted 114 km (70 miles) in the spring, 202 km (126 miles) in the summer, 255 km (158 km) in the fall, and 71 km (44 miles) in the winter, all in a northeastern direction along the northeastern U.S. coast (Chavez-Rosales et al., 2022).
Habitat
A sperm whale's blowhole is at the front of their head.
In New England, most sperm whales are generally found near the edge of the continental shelf, and beyond. During aerial surveys, sperm whales have also been sighted in shallower waters south of Martha’s Vineyard and Nantucket islands from August through November. The few live sperm whales seen in New England have usually been very young calves, but two large adult males have washed up on Nantucket in recent years. The first was a 14.3 m (47 ft) animal that stranded alive on Low Beach, Siasconset, on December 30, 1997. Its skeleton is now on display in the Nantucket Whaling Museum. The second was a 14.0 m, 41 Mt (46 ft, 45 ton) whale that washed up on June 7, 2002, at Great Point. The skeleton of this animal is now on display in the New Bedford Whaling Museum. Since 1900, at least 20 sperm whales have come ashore in Massachusetts.
Healthy habitats are vital for supporting native wildlife and plants. Explore habitats and learn about conservation and restoration in Massachusetts.
Threats
Marine mammals, particularly the large migratory whales and porpoises in the Northeast, are experiencing high rates of ocean warming, acidification, and other climate impacts to affect their distribution, phenology, and population dynamics (Letrick et al., 2023). Relatively few studies of marine mammal responses to climate change exist in part due to the difficulties in detecting and tracking their populations over the broad spatial scales that constitute their geographic ranges. Several of the large migratory whales have shown shifts in range and phenology over recent decades; however, the rate, magnitude, and direction of these shifts vary widely across sub-regions of their range and studies (Ramp et al., 2015; Charif et al., 2020; Pendleton et al., 2022). These conflicting patterns of earlier or later arrival may be due to the different methods used to monitor populations (e.g., acoustics vs aerial visual observations) with different detection abilities and spatial coverages.
A pod of sperm whales.
Shifts in the distribution of marine mammals are largely attributed to the indirect effects of climate change, as prey availability, abundance, and quality are altered due to ocean warming and acidification. Planktivorous species like North Atlantic right whales, which depend on seasonally reliable concentrations of highly nutritious and lipid-rich calanoid copepods, are more sensitive to bottom-up changes in primary and secondary production compared to piscivorous whales (Pendleton et al., 2022). However, rapid warming in the Gulf of Maine is having broad impacts on regional food webs with ramifications not only for whales but many other marine fish and seabirds that consume zooplankton or planktivorous forage fish such as sand lance and herring (Staudinger et al., 2019; Pershing et al., 2021). Most notably, increasing SSTs are negatively affecting cold-adapted subpolar copepod species, including Calanus finmarchicus through decreased growth, productivity, and shifts in overwintering phenology schedules (Staudinger et al., 2019; Staudinger et al., 2020; Pershing et al., 2021).
As food resources become increasingly unpredictable, migratory whales are occurring in unexpected locations and at unexpected times or showing elevated mortality and stranding rates, as indicated by the declaration of “Unusual Mortality Events” in the region (NOAA, 2024)1. This increases the potential for conflict and the incidence of injury and mortality of these already at-risk and endangered species with human activities such as shipping, fishing, and wind energy development.
Conservation
Consistent and expanded distribution monitoring of whale and porpoise populations is needed to better track populations over time and space and predict occurrence, especially as wind energy development areas are pursued and a better understanding of the distribution and occurrence of key prey populations and their responses to climate change. The region's most important and least understood populations that are shared prey across whales and other RSGCN include calanus copepods, C. finmarchicus in particular, and forage fishes, including sand lance, Atlantic herring, and river herring species. Studies on the physiological responses and energetic demands associated with climate-induced shifts in distribution, phenology, and foraging behaviors in marine mammals will help fill key knowledge gaps and increase understanding of changes in population changes due to altered growth and survival rates. Model projections of climate-induced distribution and phenology changes paired with current and future fishing areas, shipping corridors, and wind energy development areas can aid marine mammal conservation efforts by identifying intersecting spatiotemporal risk areas under different closure and operation schedules scenarios.
Stranded Whales
For all live or dead marine mammal strandings, please call one of the following hot lines:
For Cape Cod: 508-743-9548 (IFAW Marine Mammal Rescue and Research)
For all other areas: 866-755-NOAA (Northeast Marine Mammal and Sea Turtle Stranding and Entanglement Hotline)
Be prepared to provide the following information:
- Name and contact number
- Location of animal with detailed description and nearby landmarks, if possible
- Number, size, and type of animal
- Any other helpful information such as behavior or tidal cycle
- If the carcass is marked with grease pen or tagged, note the tag’s color, number, and position on the animal
- Keep a safe distance away from the animal.
References
Sperm whales (Physeter macrocephalus). Office of Protected Resources. NOAA Fisheries. URL: http://www.fisheries.noaa.gov/pr/species/mammals/whales/sperm-whale.html
National Marine Fisheries Service. 2010. Final Recovery Plan for the sperm whale (Physeter macrocephalus). National Marine Fisheries Service, Office of Protected Resources, Silver Spring, MD. 148 pp.
National Marine Fisheries Service. 2015. sperm whale (Physeter macrocephalus) 5-year Review: Summary and Evaluation. National Marine Fisheries Service, Office of Protected Resources, Silver Spring, MD. 58 pp.
Contact
| Date published: | March 14, 2025 |
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