topo maps and brook trout
"briang" posted an interesting topic in the discussion forum earlier today and it got me thinking about an article I have been promising to write. How does one go about finding fresh water for pursuing native brook trout? I am a topography map junky and spend countless hours pouring over my maps looking for relatively unknown waters throughout the Northeast and Midatlantic. It started off as a simple visit to TopoZone.com but I quickly tired of hours of slow internet-fed scrolling. Now I use National Geographics Topo! software and buy map packs for areas that I am interested in exploring. The maps are clear and the software allow me to connect to my GPS via USB or a serial port so I can transfer where I am going and where I have been.
There are other tools on the market and paper maps available for the less technically savy or more traditional folks but topo maps are clearly one of the best ways to scout new water from the comfort of you easy chair. The trick is in knowing what to look for. Keep in mind, just because a site meets all my criteria does not guarantee that there are native brook trout in a given stream. Many things can affect brook trout habitat. One little accident and a stream can lose it's brook trout population forever. Also the maps are dated and don't include all of the latest development. Clearing of forest can allow water temperatures to rise and kill off a brook trout population in one summer.
That said here is what I look for!
reading the topo map - example one
A Small Stream in Pennsylvania
Here is a great example of a mystery stream that I found using topo maps. It has all the characteristics I look for in a PA stream. I have listed my criteria and will apply it to two locations to show you how I do it.
If you can't get to it, you can't fish it. This is a no brainer. No sense trying to find streams that require a two-day hike just to reach and find that acid rain has killed off the population of native fish. This stream has a highway running right next to the access area. One bummer here; the access is private! Fortunately some good will and a promise to release all fish got me right in. Most lands are posted to prevent hunters from entering, very few people have problems with catch-and-release fisherman.
Cover and Protection
You will notice that the stream is entirely surrounded by undeveloped woodland and other than Jeep trails (which no longer exist) can only be reached on foot. There are no buildings on or even near the stream which means little chance of contamination from sources like petroleum, fertilizer or pesticides. Additionally the lack of dwellings means the cover will likely be very, very thick preventing sunlight and other fisherman from reaching the stream. Finally notice that the headwaters are completely protected by this cover. No matter how pristine a valley is, if the headwaters are not protected you will probably not find native brook trout. Take a look at Rock Creek Park in Washington, DC. Beautiful stream, good cover and steady flow but horribly polluted headwaters means hardly a fish to be seen, much less a native brook trout.
Constant Flow and Temperature
This one is a little tougher to discern from a Topo map. I have scouted many streams via topo maps only to find they dry out completely in drought conditions. Fortunately in the area where this stream is located that is seldom a problem. Lattitude also plays a part here. Water flow and temperature are often affected by lattitude. The further south I got the higher in altitude I look. Once again this location doesn't suffer from that problem.
reading the topo map - example two
Blue Ridge Bliss
This is an example of a cool tributary off of relatively well known stream in the Blue Ridge Area. Just like the Pennsylvania example we are looking for cover, protected headwaters and good flow. Something else we look for as we head south is elevation. By getting up in the clouds we can find an important resource to the fly fisherman that says "Y'all"; cold water. Another feature I look for on southern streams is elevation change. This keeps the water moving and oxygenated. Oxygenated water is important everywhere brook trout call home but it is especially important as we head south. Stagnant, slow moving water cannot support native brook trout.
Notice a parking area on the bottom of the image. Excellent! Also notice that there is quite a hike to the tributary in question. This will keep all but the burliest fly fishman away. The terrain is rough but passable.
Cover and Protection
This one is protected by a National Park. That pretty much assures the cover will be heavy and this stream doesn't disappoint. Headwaters are completely protected and it is adjacent to a well known brook trout stream. Get ready to be nursing that poison ivy for a few weeks while you think about your trout.
Constant Flow and Temperature
Looking at the elevation numbers you can see there is some altitude here and some major changes in elevation. This will ensure fast, oxygenated water and many, many plunge pools for anyone daring enough to hike along this rugged stream.
Okay, you found a promising stream. How do you know if there are brook trout? Between mid-March and the end of October the best bet is to just fish. You will know within a couple of hours. If you don't catch any fish, you will at least have seen small brookies streaking upstream away from you as you spook them. It is a little harder to tell in the winter. I often need to spend all day on a stream to make an assessment in the off season. If they can, brook trout will often move downstream in the winter and hang out in deeper more temperate pools. The best time for scouting is what is usually considered the worst time to fish; mid-summer. The summer heat and low water forces the trout to head upstream and congregate in the only pools cool enough and large enough to hold them. They are extremely spooky at this point in the season and just standing upright can cause them to scatter; but at least you know they are there. This is also a good time of year for scouting because it will show you if a stream carries water year round. Many raging torrents completely disappear in the heat of the summer. In the first topo map above, I discovered an entire section of stream that disappears completely underground in August only to resurface 100 yards later. I would never have known that without my mid-summer scouting excursions. Explains why I catch so few fish in that stretch.
Hope this helps you in your quest for native brook trout.