Released 12/2013. Click on the >>>PA Downloads link in the PA Resources menu to download this file!
Note: In January, 2014 we published an improved version of the overlay which is both more accurate and easier to interpret than the “old” version illustrated here. If you are interested in Class B and lower streams, you will certainly want to download both the Class B vector layer described on this page, and the Class B-D overlay layer.
PAFBC defines a Class B stream as supporting more than 20 kg/hectare* of trout biomass, but less than 40 kg if it’s dominated by brown trout and rainbows, or less than 30 kg/hectare if dominated by brook trout. Note that a few Class B streams are “Class A” in waiting, since it can take a while for the bureaucratic wheels to certify a stream as Class A. We noted several streams in this 2010 dataset that are now in the Class A list (and we’ve removed them).
Why would you want to fish a Class B stream? Because there’s very little published information about them, they generally get less pressure than the A’s. In addition, if the structure is right, and it’s easy to spot likely holding spots, the B might actually fish better than an A which doesn’t provide such clear-cut structure. Keep in mind that a B fishery may have just as many fish as an A, simply ones that weigh less (pretty typical for small brook trout streams). So if size doesn’t matter to you as much as having a relationship with a less-fished stream, then a ‘B’ might just be the ticket. (Though check to make sure the B you want to explore isn’t stocked. ‘A’ streams are never stocked, but a fair number of ‘Bs’ are).
In 2011, we published a set of KMZ’s based on a map published in the 2010-2014 PAFBC Strategic Plan. To my knowledge, this map (and our derivatives) are the only places where this information has ever been published (except for 38 B segments disclosed in the wilderness trout stream list). We used the Strategic Plan map to create a set of visual overlays in Google Earth. These allow you to view the overlay along with stream segments and visually judge the stream class. While this is an incredible tool, it was tough to use. The geo-alignment of the images was often slightly off, requiring some careful interpretation when several streams are close together, and the color fidelity of the overlays was far from perfect. (This layer has subsequently been enhanced and is much easier to use).
As we’ve become more proficient in the use of our QGIS workstation, we realized we could create a vector dataset containing the B streams only. This is a easier to use than even the improved overlay. It won’t be perfect: recognize that the underlying data still comes from intepreting these visual images, but we’ve got a lot of experience doing that, and we’ve been as accurate as we know how. Check out the New vs. Old image of Cameron County below…
The left hand image is the “new” dataset, and the Class B streams are the blue lines. The right hand image illustrates the “old” way of doing things. You’d need to display the overlay, display the Trout Natural Reproduction layer (purple lines) above it, and pick out the streams that are on top of the blue areas. Not impossible, but not easy.
In constructing the new dataset, we also compared the overlay images to the original published map, recognizing that some of the green areas took on a blue tinge after processing in Photoshop. That’s why some of the streams you might think belong on the left have been excluded (e.g. the two streams about 2/3 down towards the lower right corner. The area looks blue, but it’s actually green in the original).
Since there’s no published list, we can’t be completely sure how accurate the final result is. However, you can think of the 38 stream segments listed in the Wilderness list is as a “random” sample, and this layer correctly identified 30 of them (77%). So, while it’s not perfect it’s no doubt pretty good.
*For those of you not raised on the Metric system, a kg is 2.2 pounds and a hectare is 2.4 acres. So you can take the biomass numbers, add 10%, and convert it to pounds/acre. Or just use the numbers as they are (10% is no doubt within the margin of error).