Scott Inlet - trawling and long lines

One of the glaciers

This is the forth installment on my field work in Scott Inlet, Baffin Island. Previous installments can be found here, here and here.

17 Sept 2013 – the ship spent the night just outside Scott Inlet starting out out at anchor, but wind and swell caused it to endlessly rub against the anchor chain. The mate, who was on watch, decided to start up the engines, pull the anchor and motor around for the night. All the while, small chunks of ice butted against the hull right beside my bunk which left me with visions of the sinking Titanic. No sleep was to be had, leaving us all looking rough around the breakfast table in the morning.

Over the course of the day we completed 5 trawls – the first time the Nuliajuk had done a bottom trawl. With each trawl, the turn-around time with the equipment sped up as everyone figured out what they were doing. Each trawl was slightly deeper than the last as no one knew exactly how much cable the trawl net had (it turns out around 900m worth). The catch included: Greenland Halibut, Flounder, Arctic Cod, Polar Cod, Alligator Fish, Snail Fish, Northern Shrimp, Striped Shrimp, other assorted shrimp, 2 species of skate, Hookear Skulpin, Eel Pout, and assorted jellies, sponges and stars. I saw none of the animals as I stayed on the bridge taking notes on times, locations and depths while trying not to get sea-sick (I could have popped down to the lab – but didn't think my stomach could take it).

For the night, we retreated to anchor in Refuse Bay. It was nice not to have to dance around to get my socks off at the end of the day.

18 Sept 2013 – We took the day to circumnavigate Sillum Island, one of two islands that Scott Inlet branches around. The aim was for me to do CTD casts while the long-lines were being set up for sharks. The occasional depth sounding of the chart didn't even hint at how complex the bottom topography is, multiple deep pools of 700 m and more are separated by shallower sills. Bumps and dips break the flat of the deeper pockets. Mostly, the depth sound returned a hard signal meaning the bottom was probably rock, but occasionally, the signal would return spread out suggesting isolated muddy patches (or something else).

Against the electric blue of the glaciers, the fresh snow looked dirty. In gullies where glaciers reached the water, calved off chunks floated away. These bergy-bits often sported whimsical shapes reminiscent of ancient monsters or partly submerged houses.

I finished the day with 47 CTD casts over a wide area, downloaded and backed up to three places (I'm mildly paranoid about losing data).

Greenland Shark complete with copepod (shark is on its back)

19-20 Sept 2013 – Over the next two days we fished for Greenland Shark deep within Scott Inlet (it was delightfully calm in the sheltered Inlet, I could set a cup of coffee cup down and not have it instantly spill everywhere). We used a long-line bated with squid for the sharks. A long-line is exactly as it sounds, a several hundred metre long line with shorter lines attached every few metres ending in hooks. Anchors weight down both ends keeping it on the bottom, which in our case was around 600 m. Off of the anchors at both ends were buoyant ropes attached to floats so we could recover everything (both ends in case we encountered a snarl and had to cut the line – then we could start again at the other end). Both days, the whole mess of lines, anchors and hooks was left in the water for 24 hours.

While I was there (shark fishing continued after I left), we caught 14 live shark and several more that had been snacked on. Sizes ranged from 1.6 m (baby size) to over 3 m with a good mix of males and females. We didn't catch anything else, so why were the shark even there? And what were they eating? The sharks were measured, tagged and tissue and blood samples were taken. The question as to why we needed the centrifuge was answered since the blood was spun to separate out the plasma.

Most sharks had a copepod parasite (Ommatokoita elongata) attached to their corneas. Each parasite dangled a finger-length yellowish egg case from the shark's eye, no doubt impairing the shark's vision (but, they live so deep, vision is probably not critical for their survival).

We brought on board a couple of shark heads (the assumption was that other sharks had eaten the rest of them). I took the opportunity to get a close up look. The Greenland Shark doesn't have flashy teeth like a Great White Shark does. Instead, it has tiny teeth reminiscent of a saw blade or razor wire. These shark bite and twist, effectively removing chunks of its prey. Up close, the teeth looked deadly.