|Section 07 of the Lackawanna River extends 8.8 miles from the Route 347 Bridge in Olyphant downstream to the confluence with Roaring Brook in Scranton. Historically, this section supported a very low density wild brown trout population. A 1979 survey captured four wild brown trout in 600 meters of sampling, but none of these fish were young-of-the-year (YOY). A 1991 survey captured 14 wild brown trout in 345 meters of sampling. Two of those fish were YOY.
PFBC biologists re-surveyed Section 07 during the week of July 26, 2010. The purpose of our survey was to obtain an updated estimate of wild brown trout density, as anglers have been telling us that the trout population in this stretch has been expanding. This was a difficult survey to accomplish because the river is so wide. As a result, we had to wait for a relatively dry summer when stream flows were low. We also had to get several different groups of biologists together to do the survey. The sampling crew consisted of the Coldwater Unit from Centre County, Area 5 Fisheries Management from Pike County, and Area 4 Fisheries Management from Luzerne County. We used two towed boat crews to cover the width of the river (Figure 1) and one processing crew to measure, weigh, mark, and take scale samples from the fish while electrofishing operations took place.
Figure 1. Sampling crew using two towed boats on the Lackawanna River at Green Ridge Street.
We sampled at four different sites. The sites we sampled were:
The total electrofishing distance was 1,383 meters. Our results this time were much better than during historic work. At all sites combined we caught 737 wild brown trout including 403 YOY. Wild brown trout ranged from 2 to 22 inches long (Figure 2). We also caught a single YOY wild brook trout and small numbers of hatchery brown, brook, rainbow, and golden rainbow trout.
The largest trout we caught was 22 inches long and weighed 2.9 pounds. There are two things to note about this. First, there are larger trout available in the river. However, these fish typically spend most of their time in the deepest pools where we are unable to sample even during low stream flows. Second, the larger trout we captured from this section were much lighter for their lengths than the statewide average (Figure 3). The reason for this was a long stretch of warm summer weather prior to the survey. We measured water temperatures as high as 78°F during our work. As a result, the larger trout had not been feeding well for some time. Warm summer water temperatures are the primary factor limiting wild brown trout abundance in this stretch of the Lackawanna. The river also suffers from combined sewer overflows, acid mine drainage, and litter. Nevertheless, wild brown trout continue to thrive.
Figure 2. Length-frequency distribution of wild brown trout captured in Section 07 of the Lackawanna River in July 2010.
Figure 3. Weights of brown trout captured in the Lackawanna River compared to statewide averages.
Pictures of wild brown trout captured in Section 07 of the Lackawanna River
|— Rob Wnuk, Area 4 Fisheries Manager|
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