Under Pressure

After a full day of early-spring steelheading trip on the Salmon River last March, I had a couple beers with owner of Tinker Tavern Lodge and Guide Service, Scott Glazier. As midnight neared and the empties began outnumbering the fulls in our case of Coors Light, Scott began dropping the kind of knowledge that good fishermen only divulge after one beer too many. The kind of knowledge that is only told to you after you’ve had one too many as well, making it iffy if you’re going to even remember it the next day. Fortunately, when I retreated back to my cabin, I still had the wherewithal to scribble down a few words to jog my memory. Among them were: pressure, microorganisms, off-bottom, get things moving.

I had been asking Scott about what factors determined whether or not the steelhead would be more likely to bite. Water level, water temperature and light conditions all came up as part of the answer, but not pressure.

I’ve heard plenty of anglers blame barometric pressure for difficult fishing, though I’ve never heard a very convincing reason why. The most popular explanation was that high-pressure systems affect fish the way we might be affected by a hangover – a sensation I’d experience first-hand the morning after my late-night chat with Scott – making them lethargic, lazy and unlikely to feed.

Scott had a different theory about pressure. In his days as a tournament bass fisherman, he spoke with marine biologists who said that part of the reason low pressure is so often associated with good fishing is because when the pressure is low, near-weightless microorganisms are lifted off the pond, lake or river bottom, drawing and concentrating the baitfish that feed on them which in turn draws the larger predatory fish. The low pressure kickstarts the food chain and gets fish and their food moving. True or not, it sounded good to me.

Whatever the reason, I’m going to pay extra close attention to the barometer this season, and when it starts to fall, I’m going to make it a point to get out on the water.

Any other theories on why barometric pressure matters to the fish out there?