The humpback whales that we encounter in Campbell River aren’t here year-round. These are a migratory whale. They spend their summers in feeding grounds in higher latitudes, like here in Campbell River. Their winters are spent in warm breeding grounds near the equator.
Temperate waters have higher nutrient and oxygen content, and support huge amounts of krill and small schooling fish that these whales feed on. Warmer waters have very little food for them, but offer protection from predators including killer whales.
During the summer months in British Columbia, humpback whales spend most of their time feeding on krill, plankton and small fish including herring. They need to build up their fat supply for the winter months, and will eat around 2 tonnes a day, that’s over 4000lbs of food! They filter prey through their baleen plates.
They have a variety of feeding techniques to gather herring and other small fish while feeding including lunge feeding, bubble net feeding, and trap feeding. In their warmer wintering grounds, they consume almost no food and instead live off of their fat reserves for energy during that time. Each humpback whale can fast for around 6 months during migration and in their breeding grounds, and can lose up to 1/3 of their bodyweight while doing so.
It’s very important for these whales to get enough food during their feeding season as their migration is 5000-8000km each way, and can take between 4 to 8 weeks depending on how long they stop along the way to feed. Pregnant females begin their migration at the end of their 11 month gestation.
Once they arrive in their breeding grounds, females will give birth to their calf. If calves were born in temperate waters, they would die because of a lack of blubber at birth. They will feed from their mother and gain a healthy blubber layer, drinking 300-400L of milk per day. The mothers’ milk is 45% fat, and the calf will gain 100lb/45kg of bodyweight per day!
Calves only stay with their mothers for about a year, so they will have one chance to learn the migration routes from summer feeding grounds to winter breeding areas. Individual whales are very likely to migrate to the same areas that they were first taken to by their mothers. This leads to high site fidelity. Most of the humpback whales feeding in northern British Columbia during summer months winter in Hawaii, and the whales in southern British Columbia have been spotted off both Mexico and Hawaii. There are estimated to be 3000-5000 humpbacks in the southeast Alaska and northern British Columbia regions, and 200-400 in the southern BC and Washington regions.
We do see some humpback whales that remain in British Columbia throughout the year. They could be wintering in our surrounding waters to continue feeding, or beginning their journey south much later in the season. The reason they are staying is still unknown to researchers.
We’re very grateful to be seeing more and more of these whales call these waters home for the 6-8 months that they’re here. It’s especially exciting to start recognizing and encountering the same individuals returning year after year to their same feeding spots, and who they’re spending their time with!