Tales of Transects & Smolt Traps

Tales of Transects & Smolt Traps

Smolt trap Mud Bay Creek

The forecast called for sun but there was a drizzle of rain on the windshield as we drove the short distance to Mud Bay Creek. We hoped to do a transect – that is, measure the stream flow – before the Fanny Bay Salmonid Enhancement folks installed their smolt trap. The smolt trap, appropriately enough, catches smolts, or baby fish, so they can be counted as they head out to sea. The problem for BWS is that the smolt trap raises the water level. Since we use the level as an indicator of how much water is flowing, anything that artificially raises the water level confuses our data. So, we try to get a transect just before and just after the smolt trap goes in and then we adjust the numbers accordingly.

We start by recording the stage, the hydrological term for water level. Then we string a measuring tape across the creek and begin taking readings at regular intervals perpendicular to the flow. While we are doing our prep work, the sun breaks through the drizzle and, even though we’re in the trees, stray sunbeams find us through the leaves. They carry some psychological warmth even if no real heat. The woods are full of robins, flitting from tree to tree, arguing over territory with their complex melodies. Our sophisticated instrument, the FlowTracker II, does all the thinking so we settle into a routine, enjoying the morning and swapping stories.

My transecting partner, Paul Anders, is a former teacher. His school used to incubate salmon eggs in a large tank in the school’s main hallway. The kids tracked the water temperature in the tank and watched for changes to the eggs over the course of the winter. In the spring, the kids took the newly hatched fry to Rosewall Creek. It was an exciting event for the kids, carrying their “pets” to the creek in buckets. They poked them, talked to them, and named them as they released them into pools along the creek bank. The kids watched as the fish skittered about, cautiously exploring their new, more expansive home.

Then thwack! Imagine the children’s horror as a huge brown trout darted out from under a log and, in a flash, gobbled up half of the little fish. A fun day ended with a hard lesson. Nature can be a merciless tutor!

Our transect is finished and we begin packing up. Nature is kind today and has nothing to teach us except that it feels good to be in the creek, in the dappled sunlight, after a long winter.

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