Ocean sunfish are normally found in tropical and temperate waters — but they have been showing up off BC’s west coast. Photo: Wikipedia

Ocean sunfish are normally found in tropical and temperate waters — but they have been showing up off BC’s west coast. Photo: Wikipedia

COLUMN: Will Vancouver Island become home to tropical species?

Warming winter waters off BC’s coast has resulted in some previously unusual fish sightings

By Ronja Perner and Travis Hoogland

It is time for your annual family trip to the west coast of Vancouver Island. You are having a nice relaxing time reading a book while sitting on your fishing boat. It is an activity you have done many times before on your previous trips.

Everything feels familiar until suddenly a grey pancake the size of your car goes floating by. It startles you, because in all the years you have visited this spot you have never seen anything like this before. Curious, you take a closer look. To your surprise you realize it is a living creature. That creature is known as a sunfish or a Mola mola.

The sunfish is the largest bony fish reaching up to 14 feet (4.2 meters) tall and 10 feet (three meters) long (they have long dorsal and anal fins that make them taller than they are long) and weigh up to 5,000 pounds (2,300 kg). They have an unusual body shape that looks like a giant head attached directly to a tail with no real body, giving them a silhouette of a flattened bullet. They have long fins coming off the top and bottom.

They can often be seen floating at the surface on their side, warming their body after deep dives. They do deep dives, up to 200 meters down, to prey on jellyfish and zooplankton. Despite their size they are not a threat to humans, although they can be very curious and might come and check you out.

So true they are a strange looking fish, but more importantly, they are not supposed to be here! Sunfish are traditionally found in warmer waters in tropical climates. In the last number of years, we have been experiencing warmer ocean water temperatures off our coast. The tropical fish are simply following the warmer waters. Right now a patch of warm water known as “The Blob” is off the west coast of North America.

These warm waters are a natural occurrence during the summer months as a part of the ocean currents. The water is warmed up at the tropics and is then moved out towards the poles. This warm water would traditionally be broken up by large storms and wind events that coincided with the frigid Arctic winters. But the reason the warm water is not being broken up is because Arctic winters have been milder than usual, meaning less severe storm and wind events.

The warmer winters mean the water on BC’s west coast is staying slightly warmer than usual and thus allowing for marine life adapted to tropical climates to move in. Not all species like the warmer waters. Some like salmon evolved in cooler waters. Just at the tropical species follow the warm water, so will the cool adapted species follow the cold water and likely move further north.

The effects of this habitat shift is unknown. Will it simply be a move to a new habitat or will it be so disruptive to cause damage to the fish stocks? The results of this potential shift will not only affect the West Coast but also the communities and wildlife that live up the rivers and rely on species such as salmon for food as well as industry.

What exactly will happen to Vancouver Island’s ecosystem might be difficult to predict as it is influenced by so many factors. Almost certain, however, seems to be that we will all be facing changes in the natural world. Thanks to their peculiar appearance, the sunfish off the shore of Vancouver Island is just one obvious indicator.

Ronja Perner and Travis Hoogland are second year recreation, fish, and wildlife students at Selkirk College in Castlegar.


COLUMN: Will Vancouver Island become home to tropical species?