By the numbers

We live in an amazing time. There is a mountain of data available to the public to use for purposes of fishing studies. In Pennsylvania, we have around 15,000 miles of wild trout streams. That’s a daunting number, and when you’re hunting for a specific fish, it seems unmanageable. However, using some data and tools that are available for everyone, we can break down these thousands of miles of stream into specifically what we’re looking for.

In this post I’m going to go deep down the rabbit hole of using this data to narrow down what streams to explore. This is about as geeky as you can get in fly fishing I think. Hopefully some of this is useful to someone out there.

The above is just an embedded Google map with nothing but water showing. Just as a visual aid for the amount of streams we have to sort through to find the right ones. In my quest for big brook trout in PA, I typically used to simply look through the PA Fish & Boat Commission’s online mapping tool found here: http://pfbc.maps.arcgis.com/apps/webappviewer/index.html?id=65a89f6592234019bdc5f095eaf5c6ac

This is a fantastic tool for finding the streams you want to fish. You can filter the streams you want to see by using the layers on the left to view only Class A streams for example. It’s one of the best visual ways to find streams that I know of. Kudos to the state for putting it out there for our use. It is still a bit of an overview, and I wanted to find a more specific way to drill down into the data to find the streams I’m interested in.

Another useful piece of information out there for Pennsylvania is the Class A list. If you’re not familiar, Class A streams are listed as “Streams that support a population of naturally produced trout of sufficient size and abundance to support a long-term and rewarding sport fishery.” You can download a pdf list of the Class A streams here: https://www.fishandboat.com/Fish/PennsylvaniaFishes/Trout/Documents/classa.pdf

This is a great list because it gives a little more information about the streams. It’s still a bit overwhelming though, and I needed a way to narrow things down a bit. So I exported the pdf to excel so I could sort the data. You can download a copy of my spreadsheet here (keep in mind this list is updated by the state, so my excel file will be out of date):

With the list in Excel, now I can sort by the fields to look at things a little more closely. The first thing I did was sorted all of the “Brook Trout Only” streams by length. In my opinion, anything under 3 miles in length is typically pretty small water, and usually has a lot of smaller fish. There are exceptions for this, but stream length or section length is a good place to start filtering down the list.

CountyWaterSectionFisherySection LimitsLower Limit LatitudeLower Limit LongitudeLength (miles)Percent Public Ownership
Potter-TiogaKettle Creek2BrookBillings Branch to Long Run41.560790-77.680600 7.9686

In the “snapshot” above, you can see what the basic layout of the Class A list is. With this information, we can apply some filters and sorting to narrow down our choices. After sorting by stream length, the next important piece of information is % Public Ownership. For this, I applied a conditional formatting rule to color code the rows based on the % value. This is just a quick visual clue that it’s either accessible or not.

It’s been my experience that streams with less than 85% public ownership are difficult to access. Even some that are above 85% ownership have access issues. In a lot of cases, only the headwater sections of the stream are on public land, and there are no roads remotely close to them. There are even 2 streams in the state with 99% public ownership where there is no road access anywhere along the stream. The only way to access these 2 streams would be by boat from a larger river.

The next conditional formatting rule I applied was for the stream length. I used a gradient bar rule to show the length of the stream. Again, this is just a visual clue to know whether it’s going to be a sizable section/stream. There are situations where the brook trout only portion of the Class A is just a smaller section of a larger stream. Kettle Creek is a good example of this.

The final piece of data I wanted to sort by was distance from my home. Thankfully the Class A list has the Latitude and Longitude location of the start of the Class A stretch in the list in decimal form. I searched and was able to find an excel formula that will calculate the distance using the decimal Lat/Long location.

The formula is:

=ACOS(COS(RADIANS(90-L3)) *COS(RADIANS(90-F15)) +SIN(RADIANS(90-L3)) *SIN(RADIANS(90-F15)) *COS(RADIANS(M3-G15))) *3958.756

In the formula, cell “L3” is the Longitudinal position of my home and “M3” is the Latitudinal location. “F15” is the Longitudinal location of the stream, and “G15” is the Latitudinal location.

My Final Sorted Spreadsheet

I then copy/pasted the Lat/Long coordinates into google maps and looked at satellite imagery to try to determine which locations looked the most promising. Sorting through all of this data narrowed down the options considerable. Some key results of my study;

  • Of the 524 Brook Trout Only streams, only 38 of them are longer than 3.24 miles and have more than 85% public ownership.
  • 138 of the Brook Trout Only streams have greater than 85% public ownership.
  • There are only 42 Brook Trout Only streams that are longer than 4 miles compared to 67 mixed brook/brown streams.
  • I ended up with 24 possible streams based on all of my criteria from the original 524.
  • A lot of the longer streams are either completely private, mostly private, or have no public access.

To add another layer of complexity, the next thing I looked at is the Eastern Brook Trout Joint Venture’s dataset which shows the probability of brook trout occurrence along with a bunch of other useful data. I’m not quite silly enough to merge my simple spreadsheet w/ the EBTJV data and build some kind of Google Earth overlay kmz file. What I did do though was use the EBTJV mapping tool to look at my top 24 streams.

You can view their mapping tool here: https://www.arcgis.com/apps/webappviewer/index.html?id=f70da52f45304ab8be440885d32d3866

Let’s look at one of the examples. I’ll disclose a stream here which is probably no secret. It’s also not unlike a lot of other streams in the state, so it’s not like it’s some kind of honey hole. Roaring Run in Centre county ticked a lot of the boxes for my criteria. On thing it doesn’t have going for it is the Public Ownership % number, but the 67% of public ownership is in the right place. I should note also that I didn’t exclude any streams from my search based on % of public ownership. I only used it as a factor for decision making and for determining how accessible it would be.

CentreRoaring Run1BrookHeadwaters to Sink at RM 1.3840.759741-77.823922 3.926762.76037438

The nice thing is that we can use the Lat/Long data from the spreadsheet to search in the EBTJV mapping tool. Below is the patch result in the map. There are “patches” throughout the Eastern Brook Trout’s range in the mapping tool that look at the areas from a watershed standpoint. These are predictions about the area as outlined in different colors within the map.

EBTJV Location

There are a few things of interest in the EBTJV results. The first thing I look at is the conservation strategy. Restore Persistent Population & Habitats means that there has been population degradation. While that’s probably true for 100% of the brook trout’s range, it’s a good indicator here that it’s probably a smaller population than is ideal. The next useful piece of data is teh “composite habitat integrity score”. In this case it’s 40.72%, which isn’t great. I understand this to mean that it’s habitat is mostly degraded. Finally, there is the future security score, which is 19.09% in this case. That’s likely due to the stream’s proximity to development, and because this stream is near a fast growing urban center, it’s probably likely that it will lose the battle for survival in the future.

The next thing we can look at is the actual stream itself. If you click on the stream, the mapping tool will provide another set of data that is more specific to the stream. One thing to note here is that this dataset uses a bunch of numerical values to make assumptions about the area. The results aren’t necessarily accurate. I’ve found patches and streams with very very low probability of brook trout that are actually full of brook trout in real life. Sometimes the fish show up in places that probably don’t make sense from a big data crunching algorithm standpoint.

Stream Specific View in the EBTJV Mapping Tool

Of note here is that the probability of brook trout occurrence is .57, which is pretty low. In the northern tiers of Pennsylvania, you’ll see areas with probability numbers around .82, and in Maine, you’ll see them as high as .94. It’s important to look at things relatively. It’s also important to consider how much variation there is within short distances in Pennsylvania. Look at areas where you know there are brook trout and then look at the numbers.

Another interesting result of viewing the EBTJV mapping tool data is that it can uncover streams that may not be on the PAFBC lists. There are streams throughout the state that have high probability predictions and conservations strategies like “Enhance Stronghold“. That’s the kind of entry you want to see. A lot of these streams aren’t listed as Class A, and a lot of them occur fully within Public Property.

In closing, it’s very common in Pennsylvania to run into “blue lines” that have a higher biomass than Class A listed streams. It’s still entirely possible to blueline in Pennsylvania. In fact, it’s probably a better method of finding a hidden gem than all this data wrangling. Regardless, it’s fun sometimes to make up theories about where you might encounter the best brook trout fishing. It’s a good way to get excited about trying new streams. I’m thankful that all this data and tools are available to the general public.

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