Thinking Inside the Box: Sweet Arrow Lake catfish study aims to establish self-sustaining population
Thinking Inside the Box
Sweet Arrow Lake catfish study aims to establish self-sustaining population
By Tyler Frantz
Waterfowl have long been beneficiaries of man-made nesting structures, especially at Sweet Arrow Lake in Southern Schuylkill County, where cavity dwelling wood ducks regularly brood their ducklings in rough-cut hemlock boxes hanging over the water.
But there are nearly 8,000 more eggs of another variety being laid per box below the water’s surface, thanks to a Channel catfish spawning study currently being conducted at the lake by Pennsylvania Fish & Boat Commission habitat specialists.
According to PFBC Habitat Section Manager Keith Beamer, Sweet Arrow Lake was one of four lakes chosen for a statewide study to determine whether a sustainable population of Channel catfish can be established by introducing artificial spawning habitat into lakes with a previously existing adult population.
“Sweet Arrow Lake was selected as a study site because of its relatively small size in comparison to other reservoirs (meaning fish are more likely to be caught), and we know there is already a good population of Channel cats in there,” Beamer said. “What Sweet Arrow lacks, however, is an abundance of natural spawning habitat.”
“Channel catfish are cavity spawners, which means they require stumps, hollow logs and undercut banks for spawn sites. For various reasons, some lakes don’t naturally offer a lot of these preferred areas. That’s why we provided the manmade structures to see if they will take advantage of them.”
The study called for PFBC to discontinue stocking adult Channel catfish in Sweet Arrow Lake as of 2015 and for thirty-three spawning boxes to be placed in the lake during the spring of 2016. With no new fish being stocked, the study is geared to measure the natural reproduction of adults already in the lake and to assess if the population can thrive on its own over time.
Beltzville Lake in Carbon County, Bessemer Lake in Lawrence County and Butler County’s Lake Oneida also received spawning boxes to participate in the statewide study.
The boxes, constructed of rough-cut hemlock boards measure approximately 30x20x15-inches with concrete bases to anchor them down into the firm lake bottom. Channel catfish generally spawn from May to July, with a peak spawning period in mid-June. While a mating pair can produce upwards of 8,000 offspring, only around 1-percent survive to reach adulthood.
“We’re trying to determine exactly how many boxes are required per acre to establish a self-sustaining population, which would obviously result in significant cost savings for PFBC wherever lakes can hold their own in terms of natural reproduction,” Beamer said.
“We’ll continue to monitor the spawning success by sampling the fish numbers compared to the initial baseline. If at the end of our study we find that catfish populations meet or exceed historical data, then we’ll know the boxes are doing their job, eliminating the need for future stocking.”
Natural reproduction is usually the best-case scenario for the longevity of any fishery, so Sweet Arrow Lake County Park staff has welcomed the study with open arms.
“We are very happy about the potential of a self-sustaining catfish population at Sweet Arrow Lake,” Parks and Recreation Supervisor Drew Kline said. “Fishing is our number one activity in the park, so anything that is good for the future of fishing is good for Sweet Arrow.”
Kline accompanied Beamer last year when a PFBC team checked the catfish boxes for the first time during peak spawn. They discovered adult pairs in more than 80-percent of the structures, with thousands of eggs or fry occupying each box.
“It was amazing how quickly the fish took to the spawn boxes, and I know Keith’s team was really pleased with the outcome,” Kline said.
While the nest sites weren’t monitored yet this year, last summer’s usage rates were already well above the norm to be expected so early into the study. It seems to be an “if you build it, they will come” scenario, meaning once the boxes are in place, they are going to be utilized.
“It is exciting to see the structures are already being used with such a high percentage of success. That shows great potential for the years ahead, and we’re looking forward to seeing our catfish numbers grow even more substantially,” Kline said.
According to a PFBC report on catfish management in Pennsylvania, Channel catfish were originally indigenous to Ohio and Lake Erie drainages, but they did not originally occur in Atlantic slope drainages (Susquehanna, Potomac, and Delaware Rivers). However, Channel catfish have been widely stocked in these drainages for many years and naturalized populations now occur in both the Susquehanna and Delaware Rivers.
It is suspected that necessary spawning elements are not available wherever natural reproduction does not sustain a fishery due to their specific spawning requirements.
Successful reproduction requires water temperature to reach 80-degrees F and overhead cover in which to construct a nest, spawn and incubate eggs. Hatching occurs in about one week with the male remaining with the nest through hatching. Channel catfish will not spawn in clear water without overhead structural elements according to previous studies.
0 Response to " Thinking Inside the Box: Sweet Arrow Lake catfish study aims to establish self-sustaining population"
Post a Comment