Warming Pacific means more great white sharks swimming in B.C. waters
Published Wednesday, July 26, 2017 1:39PM PDT
Climate change could mean one of the world's most feared apex predators will be more common in Canadian waters.
Playing off one of the best-known quotes from the movie "Jaws," researchers at the University of British Columbia warned: "If ocean temperatures continue to climb, you're going to need a bigger boat."
Part-way through the Discovery Channel's "Shark Week" the university published a short interview with William Cheung, an associate professor at the Institute for the Oceans and Fisheries at UBC. Cheung studies the impact of climate change on marine ecosystems.
"Based on my team’s computer simulation modelling, we found that climate change will cause an expansion of the range of great white shark to northern temperature areas, including the offshore waters of the northeast Pacific, which includes B.C.," he said in the interview.
Great whites, also known as white pointers and white sharks, are not unheard of in B.C., but are most commonly found off the coasts of California and the northeastern U.S., Australia and South Africa.
Experts including Cheung predict that the massive predators, which can grow to a length of about six metres and can weigh as much as 1,100 kilograms, will travel north in larger numbers as the water temperature changes.
Cheung said other types of species seen off the coast of California can be expected to head toward Canada too, if carbon emissions aren't mitigated.
Climate change would have the same effect on the Atlantic Ocean, driving more great whites toward Newfoundland. Like in B.C., great whites have been recorded off the coast, but currently sightings are rare.
Cheung did not have an exact timeline because the ocean temperature fluctuates year to year in the Pacific. During warmer years, sightings of tropical sharks like great whites will increase. As the ocean warms over decades, the sharks' expansion north of the 49th Parallel will continue.
OTHER SHARKS OFF B.C. COAST
In addition to the odd great white, 13 other species of sharks have been documented in B.C. waters.
A guide by Fisheries and Oceans Canada shows species ranging from the green eye shark, which grows to a length of about 46 centimetres, to the basking shark, the second largest shark in the world.
Basking sharks grow to a length of up to 10 metres (33 feet), and are found near the surface. Their diet includes small fish, zooplankton and invertebrates.
Baskings are one of three sharks that can be found near B.C. that are listed under the Species at Risk Act. The sixgill shark, which grows as long as 4.8 metres, and the two-metre-long tope (soupfin) shark are also at risk.
While the basking is the largest spotted near B.C., other large sharks that swim in local waters include the common thresher shark, which can grow to 5.8 metres, the bigeye thresher and Pacific sleeper sharks which can grow to 4.3 metres, and the shortfin mako shark which can grow to four metres.
Salmon, blue and sevengill sharks can grow to three metres long, spiny dogfish grow to 1.6 metres long, and brown cat sharks grow to 68 centimetres long.
The most common species are salmon, blue, Pacific sleeper, brown cat, spiny dogfish and soupfin sharks.
Shark attacks on humans are rare, resulting in an average of about 10 fatalities per year, according to Discovery.com. The most common species involved in unprovoked attacks are great whites, tiger sharks, bull sharks and oceanic whitetips.
The U.S.-based National Oceanic and Atmospheric Administration Fisheries Service offers the following tips on minimizing the risk of shark attacks:
- Stay in groups
- Avoid being in the water in the early morning and late afternoon, when sharks are actively feeding
- Never go in the water if you're bleeding, even if the injury is minor
- Don't wear shiny jewelry in the water, and avoid brightly coloured clothing in murky waters
- Avoid areas where people are fishing
- Avoid excessive splashing
- Avoid swimming near sandbars, steep drop-offs and estuary inlets