Evaluation of a Low-Cost Smallmouth Bass Population Estimate and Angler Use and Harvest Study on the West Branch Susquehanna River, Pennsylvania

In May 2008, we tagged 485 smallmouth bass ≥ 275 mm with Floy® internal anchor tags at two locations on the West Branch Susquehanna River, Pennsylvania to estimate population size as part of a larger angler use and harvest study conducted from June-October, 2008 on a 31.6-km (756 ha) reach of the river. A Schnabel multiple mark-recapture estimate was used to estimate smallmouth bass abundance in near-shore habitats at each 4-km long site over a 4 night sampling period.  Results of the population estimates, assuming no migration over short duration, indicated that the estimated abundance of smallmouth bass ≥ 275 mm was 258 (± 60) fish/km (average of the two sample sites) and 8,152 (± 1,896) smallmouth for the entire reach.  Results of the bus route angler survey estimated angler use at 26 hr/ha and anglers caught an estimated 10,109 (± 2,416) smallmouth bass during the study period.  No smallmouth bass were harvested by the 97 anglers interviewed during the study.  However, it should be noted that a roving design would have provided more interviews than the bus route design increasing the probability of encountering harvest.  An unexpected side benefit of the project was the high voluntary tag return rate by anglers from 2008-2010 (15% of all bass tagged were reported caught by anglers).  Of the 71 tag returns we received, anglers reported harvesting only 11 fish (15%).  If we presume reporting rates to be about the same among harvest anglers and catch and release anglers, most anglers are practicing voluntary catch and release as evident in our bus route results.  The tag return data also provided useful information on the location of angler catch relative to the initial location of tagging, which in some cases extended over 90 km.  Results of this low-cost survey provided insight into smallmouth bass abundance and angler use and harvest of smallmouth bass on the West Branch Susquehanna River and further analysis will guide future sampling methodologies.