Field Work: Day Four
I have traded in my blue jeans and hiking boots for plastic coveralls and knee-high waterproof boots. That’s right; I’ve abandoned the comforts of a warm desk for early mornings catching lake trout in the wilds of the Adirondacks, as part of a multi-year project for The Nature Conservancy’s Adirondack Chapter. You might be wondering why we want to catch more lake trout after getting an initial version of the Follensby Pond population model up and running. The answer is simple: the more data we have, the better we can understand the lake trout population. So, how do we collect this data?
Field work. A lot of it.
A beautiful lake trout is the prize for a hard day’s work on Follensby Pond
It’s currently the end of day four of my month long stint in the Adirondacks. My back aches from pulling gillnets, my face and hands are tomato red from what was apparently not enough sunscreen, my knees are bruised, and I count at least five cuts across my knuckles and fingers. Follensby Pond at its deepest is 31 meters (102 feet). Lake trout are found throughout the water column this time of year, but most stay near the bottom in 20 to 30 meters of water during the day. Pulling gillnets from the depths is a terrific (brutal) workout. I have high hopes that I will look like Hercules by the end of this month.
You might be wondering “what are gillnets?” Gillnets are panels of strategically sized mesh that tangle fish around the body or gills, hence the name. We do our best to limit accidental mortality, but despite our best intentions, not all fish survive the netting process.
We also angle for lake trout in addition to setting gillnets
As of today, we have caught twenty-two lake trout. For each lake trout caught, we weigh, measure, and scan for an internal PIT tag. Each tag has a unique identification number that lets us determine whether we have caught the trout before and if so, when. If the fish are in good shape, we release them back into the depths of the lake. The few lake trout that do not survive are dissected for otoliths (ear bones that tell us the trout’s age), tissue samples, and diet analysis.
So far we have dissected three trout. It’s not a huge number, but one we are hoping to minimize as we become savvier at quickly removing lake trout from gillnets. But here is the cool part: one of those 340 mm lake trout had a 120 mm lake trout in its stomach. A mushy, partially digested fish corpse probably doesn’t sound exciting to you, but I could not be happier because we were able to extract its otoliths as well! The gillnets’ mesh is too large for the smallest of lake trout, and I need otoliths from a few youngsters to anchor down my von Bertalanffy (age with length) growth curve.
One of the perks of field work is being back in the wonderful U. S. of A. Sarah can keep her fancy Italian pasta, lambrusco, and gelato outings: I’ve got a box of Grape-Nuts and some good old New York State sharp cheddar cheese. You might find it a bit odd that I am obsessed with eating Grape-Nuts in the United States, but due to food politics, finding Grape-Nuts in Canada is like finding a needle in a haystack. And nothing makes you crave a food more than knowing you cannot eat it.
Tomorrow we set out on the lake again armed with gillnets, fishing rods, and a fish finder. It’s still early in the month and we are trying to determine the best times, places, and net orientations to maximize the lake trout catch. We work rain and shine, weekend and weekday, although thunderstorms or particularly strong winds can keep us off the lake. It’s hard work for a few fish, but “The worst day fishing is better than the best day at work.”
Before heading out to the field, I got the chance to visit the Butterfly exhibit the Jardin Botanique de Montreal …
….And visit the New England Aquarium in Boston. This amazing aquarium had a great brook trout tank, another favorite Adirondack fish.
Speaking of work, office life keeps churning on without me. Back in March, I promised I would speak more about the paper I am publishing on the seasonal variation of a frog-killing fungus in the Northeastern United States. Although final revisions took longer than expected, the paper is finally going through the publishing process and I could not be more excited. With any luck, this time next month I will be able to share the full citation from the Journal of Diseases of Aquatic Organisms.
Tune in next month to find out whether I actually look like a Greek god or whether my sunburnt skin has simply turned to leather. Or to find out how many boxes of Grape-Nuts cereal I can eat in a month.