Pacific White-sided Dolphin

Author: Isabella de Souza Dias

Common name: Pacific White-sided Dolphin.

Scientific name: Lagenorhynchus obliquidens

Size range: Maximum length of 2.3 meters.


Identifying Features: 

The Pacific White-sided Dolphin’s back is black, the sides are striped light and dark gray, and the belly is white.  They have a dorsal fin that located in the middle of the back and is very curved .  They are a very gregarious species, often seen in large groups that range from 1 to 1000 (mean: 62, median: 15, mode: 6), and will often leap clear of water.

Habitat:

Pacific White-sided Dolphins are found continuously throughout the north Pacific.  In the eastern part of their range, Pacific White-sided Dolphins are found from 20º N to 61ºN. Through out their range they are found in open-ocean and coastal waters.  In Canada, Pacific White-sided Dolphins were primarily considered a pelagic species, however since the mid-1980s their distribution has shifted and they are increasingly common in coastal waters.

Prey (food):

Pacific White-sided Dolphins eat herring, capelin, Pacific sardines, squid, anchovies, salmon, rockfish, pollock, hake and other small fish.

Predators:

Transient killer whales and sharks both eat Pacific White-sided Dolphins. When the dolphins first came back to B.C. waters, it took the Killer Whales a couple of years to figure out how to catch the fast-moving dolphins. Some Killer Whale pods drove groups of dolphins into small bays and killed them en masse but this behavior is no longer as common, suggesting the dolphins have learned to avoid this trap.

Life Cycle:

The maximum age recorded for a female Pacific White-Sided dolphin is 46. The oldest male recorded is 42. Females have their first calf when they are seven to nine years old. Length of pregnancy (gestation period) is around 12 months. When the calves are first born they are approximately one metre long and weigh roughly 15 kg. Females will nurse their calves for eight to ten months and give birth approximately every 4.5 to five years. In B.C. most newborn calves are sighted between June and August but researchers have yet to determine whether there is a defined calving season here.

Illustration by Isabella de Souza Diaz

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River Otter

Authors: Cory Davidson, Chandler North and Brianna Sheppard-Murphy

Common name:  River Otter

Scientific name: Lontra canadensis

Size:  1 to 1.4 meters in length (3.1 – 4.5 feet)


Identifying Features

The River Otter (Lontra canadensis) has a muscular body, short legs, webbed feet and rich brown fur.  The fur on their underside may be light brown to almost white.  The River Otter is three to four feet long with sharp claws, a slender body and it has a diamond shaped nose.  It weighs between 5 to 11 kg (11-25 pounds) and its thick tail is 17 to 18 inches long.

Habitat

L. candadensis is often found along the shore line of British Columbia including the Victoria area and the Gulf Islands.  They prefer marshes and wooded banks in fresh water areas but can be found along a variety of shores foraging among rocks or on sandy beaches. They create burrows around land habitats close to the water and are comfortable living in the space under docks at marinas.  River Otters stay close to the shore so they can avoid water predators.

Prey (food)

River Otters have a rapid metabolism and must hunt frequently. They eat a variety of animals including fish, clams, and frogs. They also attack beavers, and punch holes in beaver dams to collect and eat the trapped prey which include catfish, crayfish, and insects. In the ocean they often eat gunnels and pricklebacks, sculpins, and various crab species such as the Red Rock Crab (Cancer productus). They use their sharp claws to catch and eat their prey and can hold their breath under water for long periods of time using their large lungs while they are hunting.

Predators

There are a number of predators of the River Otters including bobcats and wolves and even bald eagles may take young pups. In the southern United States they are sometimes ambushed by alligators. They avoid being eaten by either fighting off the enemy or running/swimming away.

Life Cycle

River Otters breed in the winter or early spring. They can have up to three to five young pups each mating season and the pups are born blind and remain blind until five weeks of age. They can live from 13-15 years in the wild, and 20-25 years in captivity. River Otters are very playful and play games to teach their young coordination.

Photos by Lydia Young

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