Dall’s Porpoises
Phocoenoides dalli • Speed Demons of the Strait
These fast-moving porpoises are a frequent sight in the deeper channels of the Johnstone Strait. Known as the speed demons of the Pacific Northwest, Dall’s porpoises are among the fastest marine mammals in the region, creating distinctive “rooster tail” splashes as they race through the water.
Speed Demons
Dall’s porpoises are among the fastest marine mammals in the region, capable of reaching speeds close to 55 km/h (34 mph). This incredible speed makes them formidable hunters and helps them escape predators.
When swimming rapidly at the surface, they create a characteristic “rooster tail” splash - a cone-shaped spray of water that shoots up behind them. This distinctive splash pattern makes them easy to identify from a distance.
Unlike dolphins that often leap clear of the water, Dall’s porpoises rarely become fully airborne. Instead, they slice through the surface, creating their signature spray pattern.
Appearance & Behavior
They have a stocky, muscular body with a distinctive black and white coloration pattern that sometimes causes them to be mistaken for baby orcas. The body is mostly black with a large white patch on the belly and flanks.
Adults typically reach 1.8-2.3 meters in length and weigh 130-220 kg, making them one of the largest porpoise species. Males are slightly larger than females and have a pronounced hump in front of their dorsal fin.
Their small, triangular dorsal fin is positioned far back on their body and often has a white or light grey trailing edge, adding to their distinctive appearance.
Unique Characteristics
Physical Adaptations
Dall’s porpoises have unusually thick blubber for their size, sometimes up to 4 cm thick, which helps them maintain body temperature in cold waters.
Their teeth are tiny and spade-shaped, numbering 19-28 on each side of both jaws. These small teeth are perfect for gripping slippery prey like squid and small fish.
Swimming Style
Their muscular tail stock (peduncle) is uniquely adapted for high-speed swimming, with pronounced keels that reduce drag and increase propulsion efficiency.
They often bow-ride on vessels, but unlike dolphins, they prefer to ride the stern wake rather than the bow wave, zigzagging back and forth at high speed.
Diet & Hunting
Dall’s porpoises are opportunistic feeders, preying on a variety of small fish, squid, and crustaceans. Common prey includes herring, anchovies, hake, and lanternfish, as well as squid species that migrate vertically in the water column.
They often hunt at night when deep-water prey species migrate toward the surface. Their high-speed pursuit hunting style allows them to catch fast-moving prey that other marine mammals might struggle to capture.
They can dive to depths of up to 500 meters in search of prey, though most feeding occurs at depths of less than 200 meters. Dives typically last 2-4 minutes.
Social Structure & Reproduction
Dall’s porpoises typically travel in small groups of 2-12 individuals, though larger aggregations of up to 200 have been observed when food is abundant.
They often associate with Pacific White-Sided Dolphins and have been observed in mixed groups, though they generally maintain some distance from other species.
Females give birth to a single calf after a gestation period of 11-12 months. Calves are about 1 meter long at birth and are nursed for up to two years.
They reach sexual maturity at 3-8 years and can live up to 20 years in the wild, though most individuals live 15-17 years.
Fascinating Facts
They are named after American naturalist William H. Dall, who collected the first specimen.
Hybridization with Harbor porpoises has been documented, producing viable offspring.
They are the only porpoise species that commonly bow-rides with boats.
Their range extends from Japan to California, preferring waters deeper than 180 meters.
They produce clicking sounds for echolocation but are generally quieter than dolphins.
Their heart rate can slow from 110 to 20 beats per minute during deep dives.
Conservation Status
Dall’s porpoises are currently listed as “Least Concern” by the IUCN and are one of the most abundant cetacean species in the North Pacific, with an estimated population of over 1 million individuals.
However, they face threats from entanglement in fishing nets, particularly drift nets, and are sometimes caught as bycatch in commercial fishing operations. Ocean pollution and noise from vessel traffic also pose ongoing challenges.
Climate change and its effects on prey distribution may impact their populations in the future, making continued monitoring important for their conservation.
Best Viewing Times
Year-round
Most commonly seen in deeper channels and open waters. Look for their distinctive rooster tail splashes, especially when boats are traveling at moderate speeds.