Spring Creek Brookies

This culvert pool gave up 10+ fish on the first day

This week I took two trips to a stream in southern New Hampshire. It's a small stream, averaging 5-10 feet wide, but a significant portion of its flow comes from springs. Unlike most small streams in this area, the stream bed is covered with aquatic plants - it looks more like a salter stream on the Cape than a New Hampshire stream.

On the first trip I fished for a couple hours in the middle of the day, just after a rainstorm. The water was slightly stained, which turned out to be a huge benefit. There are a bunch of 4+ foot deep pools, and in those spots the stain prevented me from seeing the bottom, and therefore prevented the trout from seeing me.

I started out drifting a small wooly bugger through a deep pool below the road. On nearly every cast I felt a strike, usually coming just as the fly started to disappear into the murk. This continued to work for 5-10 fish in every pool. I was amazed that the fighting trout didn't spook the others, but I guess they aren't alarmed by other trout thrashing if they can't see an angler. I ended up fishing only 3 pools that day, but caught at least 20 trout and had takes from many more.

On the second trip conditions were a bit different. The water was lower and much clearer. No longer did I have the luxury of walking right up to every pool without spooking the fish. The day started out well, with a nicely-sized brook trout taking my humpy in the first pool. Unfortunately the fish were much spookier this time, and that was the only fish from that pool. I moved downstream, picking up a fish or two in each pool, but not nearing the same level of action as the first trip.

Biggest of the two days - caught on a size 12 humpy

Wild brook trout and wild geraniums

Things changed when I reached a nice bend pool near a beaver dam. Unlike the other pools, the fish kept hitting, cast after cast. I landed at least 10 fish, including three over 8 inches. The fish never stopped hitting, but I hooked a branch above the pool while trying to dodge a bee buzzing by my head, so I had to wade through the pool.

This bend pool was my honey hole on Day 2 - note the aquatic plants 

The number of fish in this stream is insane - I saw well over 100 fish in the less than 1/4 mile I fished, and that's just the 5"+ adult fish. When you factor in the young of the year, which usually outnumber adult fish in trout streams, the trout density of this stream must be well over 1000 fish per mile. 

The Eastern Hemlock: Guardian of Brook Trout

If you've ever walked or fly fished along a New England trout stream, you've probably noticed the dense shade of some large evergreen trees along the banks. At first glance, they look like spruce or fir, but those species generally grow only at high altitudes. These special trees, guardians of trout streams, are Eastern Hemlocks.

A hemlock-lined stream in western Massachusetts

Hemlocks prefer areas that are cool, shady, and moist, conditions met perfectly in the ravines formed by many small trout streams. Here the hemlocks grow, slowly but surely, for hundreds of years, ultimately reaching over 100 feet in the air with trunks over 5 feet in diameter. The dense needles of these mature trees provides shade year round - even on the brightest days it's surprisingly dark in a hemlock grove. This shade shields our trout streams from the warmth of the sun, helping to prevent temperatures from rising to levels lethal to brook trout.

Range of Eastern Hemlock

Unfortunately, hemlocks are currently under threat. The hemlock wooly adelgid is a parasitic insect species native to Japan. While its name may conjure up images of prehistoric beasts, it is formidable in its own right. It attaches to the base of a hemlock needle, then slowly robs the tree of its sap, ultimately leading to death. If you turn over a hemlock branch in Massachusetts, you're likely to see an adelgid on nearly every needle.

The adelgids are the puffy white balls on each needle

As of right now, the most significant threat the adelgid poses is to hemlocks in the Southern Appalachians. Because it's native to a relatively moderate maritime climate in Japan, it can't survive extreme cold, so it hasn't spread much farther north than southern New England...yet. As the climate grows warmer, the adelgid will likely be able to spread northward. I've never seen any in the White mountains, but it's all over the hemlocks in my town near the MA/NH border. The cold winter of 2014/15 probably reduced the population to some degree, but this past winter was too warm to do much damage, so they could be farther north than ever before.

A brook trout caught in shade of hemlocks

Fortunately, there is some hope. A study in the southern Appalachians found that while the death of hemlocks greatly increased the amount of light falling on headwater streams, temperatures in these streams were correlated more with proximity to groundwater sources than light levels (Study Here - it's behind a paywall, but the conclusions are in the abstract). That means the brook trout should be able to survive, but as the climate continues to warm every little bit of shade could make a difference. The adelgid has also been subject to intensive research in recent years, and new control methods, including introduction of predatory beetles and application of pesticides, have shown some promise in reducing the population.

While it looks like trout will make it through regardless of what happens to the hemlock, I hope at least some hemlocks will survive. Even if the trout don't need the shade, there's nothing quite like fishing in a hemlock-forested ravine.

Geology and the Trout Stream

The other day I was talking with Will from Flies, Fat Tires, and Family about a small wild trout stream we both fish. We both noticed that the fish there are bigger and more numerous than in similar streams, and Will mentioned that a friend from the MA Division of Fisheries and Wildlife told him electroshocking confirmed these observations.

A nice brook trout from the stream in question

A quick look at the Massachusetts Coldwater Fishery Resource List will tell you that there are a lot of wild trout streams in Massachusetts - over 1,200, in fact. But not all 1,200 have fish like the stream Will and I like. You might think that the best streams are those with the most pristine watersheds, but that isn't always true. This stream is fairly close to Boston, yet it is far more productive than several streams I've fished further west.

So why is this stream so much better? The answer is, at least in part, geology.

Bedrock and Acid Rain

Bedrock is the layer of rock that lies underneath soil, sand, and other deposits on the surface. If you've explored the White Mountains of New Hampshire, you've probably seen the granite bedrock jutting out from the thin mountain soil.

So how does bedrock affect a trout stream? Groundwater, which contributes a significant portion of the flow of most wild trout streams, flows over and through bedrock on its way to the stream. As it flows, it dissolves some of the rock, changing the chemical content of the water. For trout, the most important consequence of this chemical change is acidity.

Different trout species have different tolerances to acidity, with Brook Trout being the most tolerant and Rainbow Trout the least. But the direct effects of acidity on the trout are not the most significant influence on productivity, rather it is the effects on their food supply that translate to the quality of the stream. Most aquatic insects prefer water in the neutral to slightly basic range (pH ~7-8), and crustaceans, such as scuds and sowbugs, require basic conditions to prevent their shells from dissolving. This means that all other things being equal, a more basic trout stream will have more food, and therefore more/bigger trout than an acidic stream.

Precipitation is naturally mildly acidic (pH < 7), but in areas with significant industrial pollution (basically all of the Northeast and Great Lakes) it can be significantly worse. As this precipitation flows into the ground, the acid is neutralized by basic ions dissolved from the rock. The only problem is, when it comes to neutralizing acid, not all rocks are created equal.

Granite, which makes up most of the bedrock in New England, has very little capacity to buffer acid, so our streams tend to be more acidic, and therefore less fertile. The White Mountains are a perfect example - the fish are small and almost all wild fish are brook trout, rather than the less acid-tolerant browns and rainbows. A good counter-example would be the streams of the Driftless area of Wisconsin or the spring creeks of Pennsylvania - the bedrock there is limestone, which has an exceptionally high buffering capacity. This results in highly fertile streams with tons of insects and trout populations exceeding 10,000 fish per mile.

Applying Geology to find a Productive Trout Stream

There are many other types of bedrock besides granite and limestone, each with a different degree of buffering capacity. It can be a little difficult to figure out how a given type of bedrock will influence acidity, so the best things to look for are actual measurements of pH from the stream of interest.

For Massachusetts, a great source of data is the Acid Rain Monitoring Project run by UMass. They have pH data for most streams in the state dating back several decades.

When you look at the data, keep in mind the date of the measurement - nearly every stream will be relatively acidic in late winter and early spring when the snow is melting. Generally, streams with good buffering capacity will run between 6.5 and 8 in summer and fall. If a stream is lower than 6.5 in summer, it's probably somewhat sterile.

If you can't find any pH data for a stream, take a look at a Bedrock Geology map and identify the type of bedrock underlying the stream. Try a Google search for "X bedrock buffering capacity" or "X bedrock acidity". There are an unbelievable number of categories and subcategories of bedrock, so you might not get a definitive answer short of asking a Geologist.

For Massachusetts, the three main types of bedrock with good buffering capacity are Carbonate Rocks (royal blue on the map below), Calcpelite (sky blue), and Calcgranofels (lavender). Find a stream in one of these areas, and the fishing is likely to be pretty good.

Bedrock Geology of Massachusetts - from MA OLIVER

Conclusion

Keep in mind that there are many factors that influence the productivity of a trout stream. A stream flowing over limestone will generally be better than a stream flowing over granite, but there's more to trout fishing than productivity. If granite streams were never fun, no one would fish in the White Mountains, but obviously that's not the case. So as you explore new trout streams this spring, consider geology - just don't forget to consider everything else that makes for a great day on the water!

See also: Aquifers: Saviors of Suburban Trout Streams

Thinking About Mountains

A White Mountain remote pond.

Lately I've been craving a trip to the mountains. While I've had a lot of great fishing this winter/spring, it's mostly been in places like Eastern MA and Wisconsin. While I can't complain about the fishing, those places are pretty flat. There's something special about hills and mountains that I can't quite describe, but which is always obvious when fishing in those places.

Somewhere in the Berkshires...

Luckily it should be less than a month before I can head for the hills and fish. I'll probably start in the Berkshires, on a small stream in the Deerfield Watershed. As we move into June and the water gets warmer, I'll head up to the White Mountains. I can't wait to make a return to the remote pond I visited last year around this time, especially since it could be a long time before I get back there once I move to Wisconsin. There's also something special about White Mountain streams. The fish tend to be a little smaller than in MA, but they exist in great numbers in nearly every stream. You almost never run into another angler, but if you do, there's always another stream just a couple of minutes away.

A remote pond brook trout.

If all goes according to plan, this blog should be plastered with pictures of trout and mountain views. Unfortunately time can only move so fast!

A Week in the Whites

I spent the last week of August fishing and camping with a friend in the beautiful White Mountains of New Hampshire. The weather forecast leading up to the week looked iffy, with at least a 50% chance of rain every day, but we elected to go anyway - a little rain rarely inhibits fishing. In fact, some of my best days of fishing have come in the rain.

In the end, the weather turned out better than expected. Though we did get rained on a few times, it was mostly overcast with temps in the 60s - perfect trout fishing weather.

Our first destination was my favorite remote pond. I was hoping to match the success of my previous trips to this pond, but unfortunately conditions did not cooperate. We found the pond quite low and fairly warm. The only place we found fish was at the mouth of a frigid tributary, but we stopped fishing after realizing nearly every fish in the pond was holding there.

On Day 2 we drove north to fish a few streams originating high in the Presidential Range. The first stream emerges at over 4000' in elevation, then falls about 2500' over 3.5 miles before entering a relatively flat meadow in the valley. We knew the meadow stretch would have cold water due to the stream's high elevation and steep gradient, but would also likely have deeper, slower water than most of mountain streams, and therefore could possibly have some bigger fish.

One of the prettiest fish of the trip 

Wild Blueberries

We caught brookies in nearly every pool. It's rare to find a nice meadow stretch in New England - most meadow streams are too warm for trout. The combination of deep, slow pools and ample casting room made for some fun fishing.

Later in the afternoon we fished the Peabody River, which also has its source in the Presidential Range. We caught stocked brookies, stocked rainbows, and even a few small wild rainbows. The water here was crystal clear, and the fish were much more selective than typical mountain stream trout. The fishing was a little slower than the morning, but it was a fun challenge.

Peabody River wild rainbow

Mt. Jefferson covered by clouds

On Day 3 we packed up camp and fished the upper section of the Pemigewasset River in Franconia notch. We both caught several nice brookies in the deep pools formed from the granite bedrock. The water here was crystal clear, so we could see the fish dart through the water column to smash our hopper patterns.

Pemi Brookie with a broken mandible

After that we headed home, satisfied from a great fishing trip.

A Weekend in the Whites

This past weekend I drive up to the White Mountains for a quick camping/fishing/hiking getaway. I arrived just before dark Friday night and went to sleep, poised for an early start Saturday morning.

My first destination was the same pond I've fished twice already this year. I was on the trail at 7:00 and, thanks to my excited pace, arrived at the pond around 7:30. It was windy when I got there and I only had my 2 weight, so I moved to the back of the pond, where wind was partially blocked by trees.

I caught a few fish on terrestrials during the first hour, but after that the fishing slowed down relative to my previous trips. I noticed groups of fish congregating near round patches of lighter sediments on the bottom. I realized the lighter sediments must have been caused by springs upwelling through the bottom. The water in the shallows felt a bit warm, so the slow fishing must have been caused by warm water temperatures.

I hiked back down to my car around 11 and drove to a moderately-sized stream nearby. I tied on a size 12 hopper pattern and found fish in nearly every pool. Most were small compared to wild brookies from MA, but they were brilliantly colored and plentiful. Plus, there's nothing like fishing a crystal clear mountain stream.

I found this guy hanging out in a tiny tributary to the river I was hiking to

I hiked back to the pond around 6, hoping to catch an evening hatch, but the only fish rising were out of casting range. I caught one fish and hiked back to my car.

The next day I hiked to a new pond. The fish there are stocked by helicopter as fingerlings, but the views near the pond were spectacular. Several cliffs on the side of Mt. Osceola were visible from the pond. I caught a few small brookies before the action slowed down.

I decided to hike back down and fish a small stream I had crossed on the trail. It turned out to be a great decision. Though the stream was fairly small, the gradient was steep, so there were plenty of deep plunge pools holding fish. I even found a few large pools that were at least 4 feet deep. In one of these I caught the largest brookie of the day.

Small brookie, big appetite

It started to drizzle around noon, so I left for home, content with a great weekend of fishing.

One of the biggest pools...

...and one of its residents.