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OCEARCH to seek great white sharks in Newfoundland

STUART PEDDLE SALTWIRE NETWORK speddle@herald.ca @Guylafur

OCEARCH is bringing an expedition to Newfoundland waters in July to capture, tag, sample and release great white sharks.

Dr. Bob Hueter, chief scientist with OCEARCH, said the non-profit research organization is looking to complete its goal of 100 animals tagged and studied with this trip back to Canada after four successful years visiting Nova Scotia. Together with work done off the U.S. Carolinas and Massachusetts, they are coming close to reaching that.

Hueter said the knowledge gained from great white sharks has been invaluable.

“We started working in Nova Scotia in 2018, I believe,” Hueter said in a phone conversation from Sarasota, Fla. “We had our fourth expedition there last September, we’re planning to have one more. We are approaching the end of this first study of the white sharks of the North Atlantic this year. We’re wrapping up with a final expedition in Atlantic Canada focusing this time on Newfoundland, because we had not spent any time there whatsoever.

“But, up to this point, Nova Scotia has been the most productive area for us in terms of finding and sampling and tagging white sharks that are part of this big population that are on the east coast of Canada and the U.S.”

Previous expeditions to Canadian waters were held in September and October, but this year, OCEARCH intends to come earlier and then head across the Atlantic for expeditions off the U.K. and in the Mediterranean.

Each shark captured was caught on a hook and line and brought to the main research vessel, the MV OCEARCH, where a hydraulic platform would lift them out of the water so researchers involved in 24 projects could collect samples, affix tracking gear and collect physical data. The sharks were then released.

HIGH MERCURY LEVELS

One project has revealed through analysis of trace materials like mercury in their system that the sharks are eating high on the food chain, including seals, other marine mammals, and fish like tuna.

“The Nova Scotia animals, even though the water is … probably in many ways less impacted by pollution than some of the other parts of their range in the southeast United States, the mercury content of the animals up there is on the higher end – higher than in the south,” Hueter said.

“Atlantic Canada, in general, is probably the major source of energy for these animals,” Hueter said. “They’re up there to really bulk up and eat a lot and store a lot of energy that will then carry them through the rest of the year.”

The sharks also eat in the southern ranges, too, of course, but Hueter said it’s not the high-energy food like the seals that are available in this area.

“Something else that has become apparent in our research, is that the white sharks that come there are very sort of imprinted on very specific places. They’ve returned with great regularity to these individual sites like West Ironbound, for example.”

Telemetry data from the tracking projects has greatly helped in filling in the knowledge of the life cycle, Heuter said. The sharks’ tracks can be seen on the OCEARCH website at https://www.ocearch.org/tracker/.

HEALTHY ANIMALS

The animals in Canada are very healthy, the samples have revealed. Fecal sampling has revealed a lot about their diet. Bacterial studies have shown low diversity, and the ones that are in the mouth are killed fairly effectively by readily available antibiotics, so that data is helping inform doctors should they have to treat a bite victim, where there is a risk of infection.

Reproductive system studies and samples also show that the sharks are not looking for love in Canadian waters. That’s happening down south in the winter.

Hueter also said the size of the sharks at reaching maturity is smaller than expected by about a metre. That could have implications in the time it takes to replenish population numbers if they are reaching maturity earlier.

“(Also,) microplastics have been found … in every part of the animal,” he said. “So, microplastics are getting into these big predators.”

Underwater video cameras have also captured images of many more white sharks that have not been caught and tagged, indicating the population numbers are even greater.

Fisheries and Oceans Canada is responsible for permitting OCEARCH and DFO researchers to also benefit from the data.

INFORMING POLICY

Paige Crowell, species at risk biologist, and Mark Mclean, acting director for aquatic ecosystems for DFO Maritimes said OCEARCH and their partners continue to publish studies in peerreviewed science journals.

“This, over time, has contributed to kind of a growing body of knowledge on the species and so they’re helping to answer questions about how white sharks use habitat in Canada, their biology and their ecology and helping to better understand threats,” Crowell said.

“And all of this information that’s produced through OCEARCH and other shark research partners informs management decisions for the population as a whole as well as management decisions in Atlantic Canada.”

Crowell, who is lead on the recovery strategy for white sharks, said all of that data is taken into account as DFO drafts a recovery plan for the species.

“For white sharks in Canada, the main threat that we’ve identified, even though it’s infrequent ... is fishing and by-catch in fishing gear so the measures will speak to that and any other threats that have been identified for the species as well as monitoring the species in Canada.”

No fishery is permitted for white sharks in Canadian waters and by-catch is not allowed to be retained.

OCEARCH’S data is part of a larger picture provided through numerous research partners, such as the Ocean Tracking Network, under Dalhousie University’s Fred Whoriskey as well as DFO’S own researchers.

“The work of OCEARCH as well as the work of our own DFO researchers has really highlighted where we’re starting to see white sharks in this area and we’re starting to see the results of that with even fishing organizations taking proactive measures to avoid interactions with white shark,” Maclean said.

Fishers have in some cases delayed setting nets to avoid interactions with white sharks, he said.

“So already we’re seeing some of the information that’s being collected across the board really help support management measures, either ones from DFO or ones taken proactively by fishing organizations.”

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2022-05-18T07:00:00.0000000Z

2022-05-18T07:00:00.0000000Z

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