GRAND MANAN – Scientists at the Grand Manan Whale and Seabird Research Station (GMWSRS) are furthering their knowledge of the Bay of Fundy through studying basking sharks and lobsters.
Founded in 1981 by University of Guelph professor Dr. David Gaskin, the scientists working at the non-profit facility dedicate their time to studying marine life in the Bay of Fundy. The facility’s research projects largely pertain to endangered or threatened species in the area including prior research subjects such as the right whale and harbour porpoises.
Since 2008, the station has studied the diving behaviour of basking sharks.
The sharks dive to the bottom of the Bay of Fundy for one of their primary food sources, copepods, a microscopic zooplankton. The species is continuously diving from the surface to the bottom, making them a valuable tool for the scientists at GMWSRS.
“We get to see what the sharks are doing,” said senior scientist Heather Koopman.
Koopman and scientists at the centre tag between two and seven basking sharks annually. They’ve yet to tag a shark this year, but Koopman says there’s still time to tag this season.
“It’s been a really slim year. We haven’t put a tag on yet, but we should have,” she said. “We don’t know if that means there are less sharks here or if they’re spending less time at the surface.”
Because the basking shark doesn’t require surfacing to breathe, they can spend long stretches of time beneath the surface.
“We’re hoping August will bring us some better weather and more basking shark fins,” said Koopman. “The hardest part is finding these basking sharks. Once the boat gets to where their eyes are, they get spooked.”
Despite the basking shark being the second largest fish in the ocean behind the whale shark, Koopman says they don’t know much about their biology.
When the team can locate the fin of a basking shark, they deploy satellite transmitting tags onto the dorsal fin. The device tracks the depths the sharks dive to, as well as the temperatures of those depths.
The tags are made from buoyant material. After four to five days, the magnesium inside the tag corrodes the piece holding it to the shark, causing the tag to float to the water’s surface.
From there, the team at GMWSRS tracks the location of the tag through satellite transmissions.
So far, 75 tags have been deployed across this study.
“We’ve had a remarkable 75 recoveries,” said Koopman.
Each retrieval’s difficulty level depends on the weather and the distance from Grand Manan Island where the tag is found.
Koopman says that with skilled trackers like Dr. Andrew Westgate, a retrieval can take less than an hour once the research vessel reaches the general vicinity of the tag. If the weather prevents a retrieval, the scientists have no choice but to wait.
“You often have to watch the tag drift (virtually),” she said.
Tracking the diving behaviour of these sharks has allowed GMWSRS to develop water columns, studying the effects of climate change on the Bay of Fundy.
The Gulf of Maine is warming rapidly, but, according to Koopman, the findings from this ongoing project show that the Bay of Fundy is not following the same trajectory.
In 2012, the Bay of Fundy endured a warmer than usual year, the temperature at the bottom showing a 2 C difference. Because of that warmer than average year, the plankton in the following years were affected, consisting of less calories and fat.
“There’s been a little bit of recovery in recent years,” said Koopman. Despite the recovery, the Bay of Fundy does not see the same number of right whales, likely because of a lack of available food.
Between November and June, the GMWSRS shifts its studies to focus on lobsters.
Like the basking sharks, lobsters spend time at the bottom of the Bay of Fundy, allowing the station to continue its study of the water’s temperatures.
Through their ongoing partnership with local fishermen, they attach thermal loggers with Koopman’s contact information to the claws of female lobsters with eggs that can’t be landed. This allows the team to track where the lobsters are travelling to and what temperatures the females are choosing.
Koopman says it’s “absolutely amazing” how many calls she’s received from fishermen.
“We really rely on the captains and the fisheries,” she said.
After five years, 1,200 tags have been reported back to the station. Koopman now has 163 lobster vessels reporting back, with some reports coming from Maine and Nova Scotia.
Because lobsters are sensitive to temperature, their findings – which range in variability by a degree or two depending on the month – are intriguing to the scientists.
“It’s interesting to see they don’t experience the same temperatures,” said Koopman.
The team of scientists at the GMWSRS conducts invaluable research, continuously expanding their knowledge of the Bay of Fundy and its inhabitants.
heatherknight@stcroixcourier.ca
About basking sharks
- The basking shark has a conical snout with gill slits extending nearly entirely around the top and bottom of its head.
- Canada’s Species at Risk Act (SARA) listed the basking shark as endangered in 2010, providing it legal protection.
- Their seasonal movements are not greatly known; however, they are said to be a high migratory species. A baking shark tagged in Europe swam across the Atlantic, ending up in the waters of Newfoundland.
- The sharks swim with their mouths open, filtering plankton and other crustaceans from the water with the use of their gill rakers, the water leaving their bodies through their gill slits. Copepods are a main part of their diet.
- Their reproductive habits are not well known. It is believed that the species are ovoviviparous, meaning they give birth to live pups after a two- to three-year gestation period.
- The estimated population of basking sharks in Atlantic Canada is approximately 10,000.
- A single basking shark’s liver can provide 200-400 gallons of oil and historically the species were harvested for that purpose, to provide oil for lamps and machinery.
- Because the sharks are easily tangled in netting, they were considered a nuisance to fishermen in the western part of Canada. Though the goal to eliminate the sharks has changed, the basking shark’s population was severely depleted and still has yet to recover today.
Source: Fisheries and Oceans Canada