The last few days of prey sampling were fortunately very successful as we were able to collect several zooplankton samples in relatively close proximity to bowhead whales. It seems likely that the whales were feeding deep in the water column–possibly grazing on small crustaceans (Calanoid copepods) that are about the size of grain of rice. But, without having the ability to sample discrete depths in the water column, the exact location of the prey will remain unknown. Hopefully next summer we will be able to sample the vertical distribution of the prey to gain a better understanding of how zooplankton aggregate in the water column.
In addition to spotting several whales in Cumberland Sound, we also encountered a few icebergs along the way…
On our last day on the water the wind picked up and we had a pretty sloppy trip out to Cumberland Sound. Conditions like these are definitely not ideal for sampling because it quickly becomes very easy to spill your organisms while you are trying to remain (at least somewhat) balanced in a teetering boat. It might not seem like a big deal to loose a few organisms here or there, but spilling even the teensy tiniest amount results in underestimating the total amount of prey available in the water column. A good friend of mine taught me how to process zooplankton samples years ago and while doing so he would frequently say “dryness is your friend”. I think this repetitive saying was made largely as a reminder to not spill my beaker full of seawater and plankton (I went through a clumsy phase while getting acquainted with the lab). Regardless of the origin of the saying, this little mantra has stuck with me.
So instead of risking the loss of samples and perhaps our breakfast jerky, we headed back into Pangnirtung Fiord. While steaming towards the harbour with flat calm seas, our Captain Ricky asked with a smile on his face, if we should take a zooplankton tow. Since our previous sampling strategy involved locating large groups of whales, sampling in an empty fiord seemed ridiculous. But, after a few minutes we decided why not, it was nice outside and I don’t think we were ready to go back to land. So we dropped our net into the water and sent it down to just above the sea bottom (only 30 m). With no animals in sight (including sea birds, fish or seals) we didn’t expect to come up with much as Eric (the Captain’s son) hauled up the net. What we did find though, was one really bright orange pteropod.I don’t think that either one of us expected to land a large haul and we realized that it was just as useful to know what isn’t found in areas where bowheads are absent (negative data is still data) just as it is important to know what zooplankton is present in areas where bowheads concentrate.
Pteropods are free-swimming pelagic sea snails and sea slugs that are named after the Greek meaning for “wing-foot”. Shell bearing pteropods (i.e., sea snails) are at risk in the Arctic Ocean due to ocean acidification, which can corrode their structural armour.
Once we finished washing down the net and pouring the sample into the jar we headed back into the harbour. The next day I would be heading out into Cumberland Sound with the multi-species research crew onboard the M/V Nuliajuk for three days of turbot (Scophthalmus maximus) fishing and zooplankton sampling.
Thanks for checking out our field note. Stayed tuned for another update on deep-sea fishing!