Last Thursday a colleague at the Bamfield Marine Sciences Centre called to tell me that a large female bluntnose sixgill shark had been found dead along the shore of the Alberni Canal on the west coast of Vancouver Island. Second-hand reports also claimed that pups (the name given to baby sharks) were coming out of her.
As the primary author on the federal status report on this species, I was aware that, despite its global distribution, only a handful of mature pregnant females have ever been observed. Colleagues at the Department of Fisheries and Oceans managed to assemble a couple of people to take scientific advantage of the unfortunate situation.
I also took the opportunity to see the shark. Indeed, it was impressive. She was 4.2 metres long and weighed about 570 kilograms. The dissection found that she was still carrying 33 pups. There was no obvious human cause for its death. Samples were taken that can be used for contaminant testing and genetic analyses.
Biologists believe that mature females live most of their lives in deep waters off the continental slope and only come inshore to give birth. Studies of sixgill sharks in Canada's Pacific waters have only ever observed immature individuals.
Sixgills are listed as "Special Concern" under Canada's Species at Risk Act. These sharks were fished heavily in the 1940s for their liver oils but are now only caught occasionally as bycatch, primarily in groundfish longline fisheries for halibut, sablefish and dogfish. Just a month ago, I was involved in a meeting hosted by DFO to develop a management plan for this species. Part of the plan is to collect information on sightings and basic biology.
Slowly, sharks are getting the conservation attention they deserve in Canada. Sharks have roamed the world's oceans for tens of millions of years and are exquisitely adapted for their environments. Nothing in their history has prepared them for the onslaught of pressures they receive from human activities, particularly fishing.
In Canada, approximately 100,000 blue sharks are caught each year as bycatch in our pelagic longline fishery for swordfish. Despite this egregious fishing practice, the swordfish fishery is on the verge of becoming eco-certified by the Marine Stewardship Council.
My glimpse into the unknown life of the female sixgill shark made me question how much we know about any of these shark species. In a few weeks we may have a Canadian eco-certified fishery that kills tens of thousands of blue sharks, not to mention sea turtles. I don't believe our understanding of these sharks or their role in the ecosystem is sufficient to be labelling this fishery "sustainable". Stay tuned; we may need your help.