Welcome to another Wildlife of the Week which brings an opportunity to learn about another excellent Salish Sea species! What species have we chosen this time? Well, it is a small and quite common (but equally elusive) cetacean that you may or may not have caught a glimpse of before. The animal is not a dolphin, though it may appear as one, due to a few key differences.
The Harbour Porpoise (Phocoena phocoena) is an important component to the Salish Sea ecosystem. Has anyone seen a Harbour porpoise before? Was the animal alone, or in a group? The Harbour porpoise is often seen alone or in small groupings (6-10), however occasionally large “superpods”can be spotted. These are estimated to possibly number into the hundreds at times! To learn more about this mysterious creature, read on!
The Harbour porpoise is small compared to its whale and dolphin relatives; reaching only a maximum length of 5-6 feet (1.8-1.9m). The animal weighs between 130-200 pounds (60-90 kg). Unlike some other cetacean species, the females typically range larger in size than males. This species has a dark black/ grey/brown back with a lighter belly; this “countershading” is common in whales, dolphins and porpoises and helps them to blend in with their ocean surroundings. A small grey stripe extends along their side.
Perhaps one of the most useful ways to tell a porpoise (like the Harbour porpoise) apart from a dolphin is by identifying the shape of the dorsal fin. The Harbour porpoise, similar to other porpoises, has a wide, triangular and pointed dorsal fin. In this same respect, this species and its porpoise relatives have rounded, blunt snouts instead of an elongated beak and melon.
The Harbour porpoise, as with the vast majority of other porpoise species, tends to favour higher latitude waters above tropical ones. This is a species that is found in the northern reaches of the globe, such as temperate and subarctic regions. They encompass various seas such as the North Pacific, North Atlantic and the Black Sea. They tend to favour coastal and inshore areas rather than open ocean.
The Harbour porpoise carries with it an extensive network of small, conical teeth that aid it in capturing (and hanging onto) slippery prey; food items like sardines, pilchard and herring ( schooling fishes). The Harbour porpoise boasts 44-56 teeth in its mouth. Often, large groups of Harbour porpoise may be spotted feeding together.
Like other cetaceans, the Harbour porpoise is vulnerable when young. At birth, the Harbour porpoise is not very large at all at only a mere 70-90 cm and 14-22 pounds. The calf is nursed for about ¾ of a year with its mother, depending on her thick, fatty milk to survive cool waters.
The Harbour porpoise is an interesting species in itself, but is more difficult to spot than some larger cetaceans due to its small size and shy, brief surface behaviours. They are not as outgoing as some other porpoises and dolphins, who may more frequently leap out of the water and even “ride the bow waves” of boats. To spot a Harbour porpoise, conditions must usually be quiet, calm and clear.
Harbour porpoises are a frequent prey item for Salish Sea’s “Bigg’s Killer Whales”, who also prey on other marine mammals. Bigg’s Killer Whales must remain quiet when hunting for marine mammals, as a species like a Harbour porpoise might easily detect their calls. The Harbour porpoise is threatened by present-day human impacts in the form of entanglement in fishing nets, chemical pollution and human-induced habitat changes. The species has been affectionately known and nicknamed by many (see below).
To test out your knowledge further with the Harbour porpoise, try out some trivia below!
- True or False? Harbour porpoise may sometimes be found within rivers. (ANS: True! The Harbour porpoise may wander into bays and large rivers from the ocean).
- How long is gestation for this species? (ANS: About 11 months).
- The Harbour porpoise may consume _____% of its body weight/ day? (ANS: 10%).
A common nickname that the Harbour porpoise has earned from fisherman, naturalists and whale-watchers is ______? Hint: it is derived from the sound of their short breaths at the surface combined with a translation for their Latin name.
Authored By: Alexa D./ Five Star Whale Watching.
To learn more, read on with our References below!
“Harbour Porpoise.” American Cetacean Society. https://www.acsonline.org/harbor-porpoise.
“Harbour Porpoise.” Whale and Dolphin Conservation. https://uk.whales.org/whales-dolphins/species-guide/harbour-porpoise/.