High water levels made it difficult for federal and state managers to count salmon all across the Yukon Kuskokwim Delta this year, which can have real effects on salmon management in the area. Aaron Webber, a fish biologist with the U.S. Fish and Wildlife Service, says that high waters can bring more uncertainty to a job that already has plenty of it.
“Tundra turds. I didn’t wanna say it on air, but yeah, tundra turds," Webber said.
Tundra turds, as they are nicknamed, are basically huge pieces of dirt that break off when river banks are eroded. These can float down the river and get stuck in weirs, which are the fish counting machines used on local rivers.
“Every day the technicians have to go out and sometimes push sections of tundra that weigh hundreds or even more pounds over the top of the weir, which is just an amazing task, Webber said.
Webber manages counting operations at the Kwethluk River weir, one of two federally run weirs in the area. He says that high water causes these tundra turds to come downriver in higher than average numbers. This can be a big distraction because workers are supposed to be counting fish, not moving dirt. Debris can also damage the weirs, making holes in them that fish can get through without being counted.
When they’re working, weirs are basically dams in the river with a hatch that opens to allow fish to swim through a small area and be counted by workers. In this case, they use a camera to record fish passing.
“Each day we look at the video that we have, and if the weir is fish-tight we’re pretty certain that we have a census of what goes up[river]. Now when it’s not fish-tight, when we call it not fish-tight that means there’s water going over the weir to the point where a fish, if it wanted to, could swim up and over the weir, then we call it not fish-tight," Webber said.
If the weir isn’t fish-tight, counts can be difficult to make. The Kwethluk weir was fish-tight for less than a month this summer, so it didn’t record as much of the data Webber hoped it would. But it still managed to record that sockeye salmon in that river met escarpment goals, which is valuable because it could mean conservation efforts are working.
Why is this information important? Lou Coggins, fish biologist for U.S. Fish and Wildlife, explains.
“The run reconstruction is informed by a whole bunch of different pieces of information; the weirs are one of them," Coggins said.
The run reconstruction is a projection constructed by numbers from many different sources. State biologists put these numbers together to find out how many of each type of fish were in the water this year. These numbers include not only data from weirs, but also data from aerial surveys and other tools. Managers then take that data and decide things like how many openers there should be, and when they should take place, but it can be challenging to make those decisions when dealing with so much uncertainty.
"Actually, the more important thing is what is the run reconstruction is used for and how is that tied back to management," Coggins said. “We are trying be very transparent in the way we portray uncertainty in discussions with the inter-tribal fish commission, and Fish and Game."
Uncertainty is a concept that is not new to fisheries management; there are too many variables to control for, and estimates have to be made. Coggins says that involving tribes will help people better understand how uncertainty is dealt with, and though this was a hard year for the weirs, Coggins says the modeling tools scientists are using to make predictions are better than ever. As for what this could mean for next year, the numbers are not in yet.