Sunday, February 11, 2024

Traprock Brookies

 I've fished wild trout streams through all sorts of substrate and geology. Classic limestoners, freestones through limestone bedrock, marble, quartzite, granite, gneiss, schist, sandstone, brownstone, conglomerate, alluvial substrate from clay to cobble, glacial till, even muddy lake beds. But it occurred to me not long ago that I'd never caught a brookie in a stream flowing out of and through traprock bedrock. 

Traprock is a reminder of our continent's volcanic past. Millenia ago, tectonic motion let magma seep up into cracks in the Earth's crust in what is now the Mid Atlantic and Southern New England area. This magma hardened into the two kinds of rock referred to as traprock: basalt and diabase. Basalt is generally extrusive, meaning the magma cooled on the Earth's surface. Diabase typically cools below the surface. Of the two, basalt is a little more common in Connecticut. The massive, imposing mountains and ridges that run North from New Haven to Holyoke, then arc east to a terminus between Belchertown and Amherst are all volcanic remnants. Today, we drive on a lot of this, and I don't mean that our roads go over these rocky slopes. Basalt is very uniform in it's crystallization and also very hard, so it makes great aggregate for road and railroad beads, and is used in concrete and asphalt as well. Basalt is a staple of the development, industry, and infrastructure of our world whether you knew it or not. Unfortunately that means the quarrying of it has negatively impacted the species that utilize the environments that evolved around these geological features. That includes species like red cedar, blue spotted and Jefferson's salamanders, northern copperheads, red squirrel, and peregrine falcons.

Female Northern copperheads often rely on the crevices on open trap rock ridges to gestate and birth their young.

But what about brook trout? Are there any small streams on or along these traprock ridges, and do they have brook trout in them? 

The very nature of these geologic features doesn't make for an ideal situation for a coldwater stream habitat to arise. First of all, spatially they aren't huge, so there just isn't that much room. Traprock ridges are narrow and tall, their shape lends better to streams running along or between them in the sedimentary rock they intrude rather than on the dykes themselves. But there are a couple streams that emerge from them and run some distance, and they have heavy spring influence so those that aren't season seem to stay cold. 

My decision to try to catch a traprock brookie was followed by the sort of oddball research I don't often hear about other small stream anglers doing but which isn't at all unfamiliar to me. I lined up bedrock maps with topographic maps to find streams that ran not just near trap rock but through it. Then I examined some satellite imagery to get an idea of the stream's consistency. I have enough experience to tell when a mapped stream is likely to be the sort that can hold water and therefore fish year round. It also gives me an idea of the forest type and what I might be in for as far as bushwhacking. Eventually I found one that looked very promising. An added confidence booster, though it had never been sampled another in the watershed had been with brook trout, albeit very few, in the 1990's and there were no dams preventing cross pollination, if you will, between the two streams. Some culverts could throw a wrench in that. Access would suck though, with questionable parking and a long circuitous walk. When the time came though, I suited up and hit the road. 

My parking spot turned out to be legal, thankfully, but proved to be a reminder of why I got an off-road capable vehicle. I parked grabbed my rod and sling pack quickly, as I had a decent distance to walk down the road and I hate being seen with a fly rod in hand. I hustled to a bridge, not on the stream I wanted to fish but the one it flowed into. This was down in the basin, in mudstone rather that traprock. I then traversed this low gradiant creek down. There was one ominously deep pool in about a half mile of difficult to negotiate water and I hooked a brook trout there. Not only did that put a new stream on my list automatically but it gave me even more hope as the survey site at the rod I'd parked on had no brook trout in the two years it was sampled. This was likely just wintering water though. Eventually I reached my stream. I looked at my map quickly as I'd saved where it crossed the line from basalt to sedimentary bedrock on the bedrock map as my starting point. It also didn't look very favorable at the bottom end, very straight on the map and shallow in real life, but where I wanted to start there were some bends and much steeper gradient. So I hoofed it upstream, staying out of the water but stopping to fish the two decent looking runs I did see. 

Just as I reached the point I'd marked I could see a good deep, slow pool upstream. The hope was there to put this goal to bed and fast. I had on a size 12 Ausable Ugly and was fishing each pool upstream, which would work well with this one as it was blocked by brush near the head. I covered the tail- as there is often at least one fish in the tail of a pool like this in the winter -to no avail. But as I extended my cast the water I was fishing held promise in the for of exceptional depth. I let the fly fall and there was a discernable but delicate tap. The next cast in the same spot I was ready and the fish was on. Success! The fish was diminutive and far from the most colorful example of her species, but that was all I'd needed. I continued upward and caught one more fish and missed some others, all very small, and decided to bother them no more. The day had been a fantastic one already.

 Though this may seem like an extremely trivial goal to have achieved and perhaps an unnecessary one for just a couple tiny brook trout, I think many anglers miss some significant keys to the understanding of fish and fisheries. Frankly I'll be blunt... I've only twice been legitimately impressed by the comprehensiveness of understanding an individual trout angler had of not only wild trout but the totality of their habitat, movement, behavioral patterns, and the nature of their whole lives. The geology of the land and rivers plays a HUGE roll in how trout survive, grow, and behave and it is one of the foremost factors I look at to understand a stream and what potential it has. And though I may only very rarely fish traprock trout, it is a piece of the puzzle and another step toward my end goal of having the most thorough understanding of the natural world I can. 

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1 comment:

  1. A well told story that motivates me to get out and explore. It’s always fun to hook (or even just see) that first fish in a new stream. Especially when it is not certain whether they are even there.