With the glow of city lights reflecting off the Susquehanna River, Rob Wnuk slowly guided his boat along the shore.
Two poles extended from the bow of the boat, each equipped with a series of electrodes sending a light shock into the water. Powered by a generator, the electrodes temporarily stunned any fish in their path, which were quickly scooped up to be weighed, measured and counted.
Wnuk, who is the fisheries manager for the Pennsylvania Fish and Boat Commission’s Northeast Region, uses the method on the river to determine if the smallmouth bass population is increasing, decreasing or staying the same.
Last week in Kingston, the numbers proved that bass are faring well in that stretch of the river and other sampled areas.
After nearly four hours of netting and counting fish, Wnuk, PFBC biologist Aaron Frey and intern Peter Horger tallied 209 smallmouth bass, well above the long-term average (1990-2017) of 100.5 fish per hour. The bass ranged from 4 to nearly 16 inches.
Wnuk also sampled stretches of the river in Great Bend, Sayre, Tunkhannock, Harding and Berwick. The sampling is typically done in late June or July after the fish are done spawning. But over the last few years, Wnuk said, spawning has been occurring earlier so the bass survey was moved up by two weeks.
While Wnuk is more interested in the trend representing the total catch per hour than he is in overall numbers to determine how the population is faring, this year’s work has yielded some interesting results.
At Sayre, for example, Wnuk and his crew caught approximately 200 smallmouth per hour, which is on par with Kingston. And in Tunkhannock, things were even better with a catch rate of 330 smallmouth bass per hour, more than tripling the long-term average.
“At times we were to the point of being overwhelmed,” Wnuk said. “We were catching more bass than we could handle.”
Surveying is conducted in three 20-minute intervals. In between, Wnuk stops so fish can be counted and data collected. In addition to the 209 smallmouth bass caught in Kingston, Wnuk and his crew also captured 247 rock bass, 100 redbreast sunfish and several walleye.
Not every site yielded high numbers of smallmouth bass. In Berwick, the catch rate was near the 100 fish per hour average, Wnuk said, adding that lesser quality habitat is the issue. Still, the number of larger fish caught at Berwick was higher than average.
And that was the case overall this year.
“Smallmouth measuring 12 inches and over and those greater than 15 inches, the numbers are higher than they’ve ever been,” Wnuk said. “We’re getting higher numbers of big fish for this time of year.”
The catch-per-hour rate this year for smallmouth bass 12 inches and larger was nearly 12, higher than the average of five per hour. For bass 15 inches and larger, the catch-per-hour rate this year was just over four, continuing an upward trend.
Smallmouth bass that are 12 inches or larger are typically 4 years old, while those 15 inches and greater are 5 years of age.
“It’s been increasing every year,” Wnuk said of the larger fish. “I attribute it to an increase in catch-and-release angling. It’s very rare to see smallmouth bass on a stringer anymore.”
As far as unusual findings this year, one bass was found with sores and, in Kingston, another didn’t have pelvic fins.
Wnuk said the findings aren’t a concern considering the disease rate are far less than what it is in the central Susquehanna River.
“We’ve been lucky on the North Branch. We do see some disease here with the young of the year bass, but there’s no impact on the population because it’s well beyond carrying capacity,” Wnuk said.
One thing that has been noticeable with the annual surveys are significant swings in the catch rates of adult bass during certain years. Wnuk said the variations are due to year class strength – the number of bass produced in a given year.
This spring and early summer conditions haven’t been good for growth of young bass, and that’s something that could turn up in future surveys.
In fact, Wnuk already expects smallmouth reproduction to be poor this year.
“Reproduction is best when the water is high in April and low and warm in May and June,” he said. “This year it’s been all high, cold water. We could see the impact of that 2 to 4 years down the road.”
Reach Tom Venesky at 570-991-6395 or on Twitter @TomVenesky