PORT AUX BASQUES – One local fisherman got quite a surprise on Monday, June 13, catching more than expected in their herring net – a shark.
The shark, which was identified as a porbeagle shark by DFO Paul Barter, Fisheries Officer and Field Supervisor in Channel Port Aux Basques, has been assessed as endangered by the Committee on the Status of Endangered Wildlife in Canada. Carolyn Miri, Marine Biologist and Taxonomist at Fisheries and Oceans Canada said that based on the photo she received it does appear to be a porbeagle.
“A few of the key visual differences he used, the main one with the porbeagle species is that it’s our only shark species that has that whitish or pale patch on the free rear tip at the bottom of its large triangular, the first dorsal fin. In contrast, the white shark has a rather darkish free rear tip on that first dorsal fin. Another aspect, the porbeagle has smooth edged, dagger-like teeth, and on each side of the tooth base you’ll see a small cusp whereas, in comparison, a white shark has triangular teeth, and the edges of those teeth are like a saw blade and there’s no secondary cusps at the base of each tooth.”
Miri said it is actually quite common to see the porbeagle this time of year in provincial waters.
“The porbeagles, they’re seasonal migrants around Newfoundland in particular. This species swims thousands of kilometers every spring, every year, to arrive in about five to ten degrees Celsius waters to feed. They’re summer visitors, if you will. About late autumn, early winter the porbeagles go back down south. They basically reverse their migration pattern and head back down south for the winter. So every year for spring, summer, and fall, the porbeagles are here feeding.”
Porbeagle sharks aren’t picky when it comes to the type of fish they consume.
“They are kind of lazy sharks; we call them opportunistic because they’ll eat anything that comes their way basically. Whether it’s a net or a cod or herring trap filled with some herring, the animal will, of course, be trying to feed on whatever fish are trapped in the net, sometimes getting caught itself, just looking for a meal.”
Porbeagle shark get reasonably large considering the size of large shark species in the North Atlantic, with the females maturing around 13 years old and the males around 8 years old.
“Porbeagles are a species, we actually call them sexually dimorphic, which means the female grow larger than the males and adult females also have thicker skin than males of the same size. The maximum verified length for this species so far is three and a half meters.”
While porbeagle sharks aren’t necessarily dangerous to people, they are a naturally curious species.
“They will put their snouts at the hull of small boats or floating buoys to see what they are, and sometimes a porbeagle will take an exploratory bite to see what that floating thing is, to see if it’s food, but all of the large sharks that come up here for summer, they’re more scared of us than we are of them and they just want to be left alone.”
Regardless of the nature of the shark, and whether or not it is alive, people still need to be careful when touching a carcass because the leading edges of the fins of any large species of shark are very sharp.
“It helps their hydrodynamics when they are swimming in the water. Another aspect about large sharks in summertime is that shark’s skin is like sandpaper. If you accidentally rub it from nose to tail, it’s fairly smooth and slick, but if you happen to brush your ankle or your calf the opposite way, from tail towards head, you can get a really nasty abrasion.”
Skin on a large shark is not the same as skin on a human or marine mammals. It is actually made up of ancient, modified teeth called dermal denticles.
“That’s why people have to be very careful, and it’s best just to avoid it. Even if it’s a dead specimen, try not to touch it, even though it’s very tempting.”
Miri said the number of sharks caught in fishing nets is not something she can readily answer.
“Over the past few years, I’ve been trying to encourage commercial fishermen, and recreational fishermen as well, I’ve been trying to encourage them to let us know at DFO here in St. John’s whenever they do accidentally catch a shark, whether it’s alive or dead and it doesn’t matter what species, so that we can put it into our database and start trying to figure this out.”
Miri said she is currently unsure of what was done with this particular shark as she hasn’t been contacted about the specifics yet, but she can give clarification on why the shark likely died.
“We refer to them as ram breathers. All of our large sharks must swim to breathe; the oxygenated seawater must be flowing over their gills so they don’t drown. You wouldn’t think that a fish would drown in the water, but this is actually the case because these sharks don’t have muscles to be able to push the water through their mouth and over their gills if they are stationary. They have to keep moving. Or, for example, if they are accidentally hooked on the side of a vessel or something, if the vessel could just slowly troll along while they’re trying to move the lines around the shark to let it go, it leaves seawater still, gently at least, flowing over their gills so they have the chance to breathe and survive the accident.”
When DFO are not notified, it tends to lead holes or gaps in its information database.
“When it comes to what accidentally gets tangled up in fishing gear, we don’t have numbers that reflect reality and on top of that, our department here, we don’t have a dedicated shark research survey in our waters. We have our usual twice-a-year offshore survey, which is multi-species, but we don’t have a dedicated shark survey, so that’s another area where there’s a lot of data gaps.”
People are asked to contact DFO even if they just happen to spot a shark, and having a photo would be even better.
“It doesn’t have to be trapped or anything, but if they happen to see it when they are walking home on the beach, or maybe the carcass of a dead shark may wash up on the beach or the coastline area, I would love it if they could contact us and give us more data,” said Miri. “A side photo from head to tail would be great and if they could note the day they saw it, the approximate location, and guesstimate the total length of the animal.”
Photos and information can be tweeted to DFO, @DFO_NL, with the hashtag #NLSHARKS.
Jaymie White, Local Journalism Initiative Reporter, Wreckhouse Weekly News