Also known as the black porpoise, spiny porpoise and sea pig, Burmeister’s porpoise (Phocoena spinipinnis in Latin) was first identified by the German zoologist Karl Hermann Burmeister in 1856.
As with other species of porpoise Burmeister’s porpoise tends to be a fairly shy and timid marine mammal that prefers to remain distant from boats and human interaction, often disappearing at the sight of oncoming boats.
Their quiet nature and ability to remain undetected have made them somewhat difficult to study in great detail.
Although much has been learned in the more than 100 years since, this breed remains one of the least studied and most enigmatic members of the porpoise family.
Physical Characteristics and Appearance
Like all porpoises, Burmeister’s porpoise lacks the elongated beak evident in most species of dolphin.
One of the most distinguishing characteristics is the dorsal fin, which is set well back of the mid-body and carries a row of hard bumps on its forward edge.
This porpoises dorsal fin has a longer, lower rise than the dorsal fins of dolphins or other porpoises.
Another distinguishing feature is the marking stripes leading from each flipper back along the body are asymmetrical, being straight on the left side curved on the right.
The dark eye patches common in porpoises are surrounded by pale grey rings.
This is one of the smaller porpoises, ranging from just 1.4 to 1.8 meters (about 1.5 to 2 yards) in length and weighing from 40 to 70 kilograms (about 88 to 154 pounds) in weight.
Though males tend to be slightly larger than females, the difference is not great enough to be relied on as a determining factor of its sex.
Diet and Hunting Methods
Off the Chilean coast, they’ve also been found to feed on octopuses, snails and other mollusks.
Habitat and Migration
Burmeister’s porpoises are native to South America, inhabiting the coastal waters off both the Atlantic and Pacific shores.
On the Atlantic side, they are found from Rio de Janeiro all the way south to Tierra del Fuego, an area that includes the Falkland Islands.
On the Pacific side their territory begins farther north, along the northernmost coast of Peru, and extends south around the tip of the continent.
They have not been found outside this coastal region.
Their preference is for cold, relatively shallow waters of about 150 meters (500 feet) deep or less, and they sometimes wander into the very shallow waters of rivers and estuaries.
It is uncertain whether they inhabit the entire coastline continuously or only territories along it.
Social Structure and Communication
Not a flamboyant swimmer, this cetacean seldom breaches and can surface to breathe without greatly disturbing the water.
Capable of deep dives and swift speeds, they are shy of boats and often seem to vanish as soon as they are noticed, making their social behavior extremely difficult to study.
They are most often seen in pairs or in small groups of 2 – 8, yet groups as large as 70 – 150 have been spotted on occasion.
Which of these social arrangements most accurately represents their typical social structure remains uncertain, as the presence of humans may significantly alter their natural behavior.
Breeding and Reproduction
Due to the shyness of the Burmeister’s porpoise, breeding habits have not been extensively studied.
Mating season is thought to last from June to September, followed by ten to twelve months of gestation, with calving season occurring from May through August.
Calves are thought to be at least 44 centimeters (27 inches) in length at birth, with females reaching sexual maturity at about 155 centimeters (61 inches) and males at 160 centimeters (63 inches).
Aside from one natural predator, the killer whale, man poses the biggest threat to this porpoise.
They are among the cetaceans inadvertently caught in fishing nets, and until the mid-1990’s both Chile and Peru shot or harpooned them, selling their meat for human consumption or for crab bait.
As a result of tightened regulations, deliberate harvesting has declined, but net entanglements have not.
One of the biggest threats remains lack of knowledge.
While some suggest the population has dwindled below the danger point, the data is not solid enough to grant them endangered species status.
In addition to hunting and bycatch (accidental capture in fishing nets) Burmeister’s porpoise may suffer from habitat degradation and pollution, however studies on this topic have not been throughout researched and remain data deficient.