MOVING ON
Some trout travel after preseason stocking
“Stream sections with better habitat — log jams, undercut banks — have better stocked trout residency.” — Jason Detar, Fish and Boat Commission
Red worms didn’t work, so you switched to salmon eggs. After a while, you took off the bobber. Surely they’d go for a stinky green paste bait. Nothing. Where are all the trout? The short answer is, they’re in there. But they might not be where you think they are.
In Pennsylvania, angler purchases of Trout-Salmon Permits pay for the raising and stocking of more than 3 million adult trout averaging 11 inches. Once stocked, it’s hoped they’ll remain in the same general area until they’re harvested. But sometimes they leave. In 2006, the state Fish and Boat Commission published a Preseason Stocked Trout Residency Study that investigated how long stocked trout stay in the stream sections where they were placed. The results impacted the way Fish and Boat stocks trout, and could help anglers to find them.
“If people are fishing in the same place multiple opening days in a row and not catching fish, that could suggest there’s a problem with trout residency,” said Jason Detar, who recently took the helm of the agency’s Division of Fisheries Management. “There could be other reasons they’re not catching fish, but it could be an indication that the trout aren’t staying in that stream section.”
Stocked trout aren’t supposed to live for long in the lakes, rivers and streams where they are placed. The goal of the stocking program is to provide recreational angling opportunities — the fish are not expected to procreate or survive longer than a few months before they’re harvested, although there are some holdovers.
The Preseason Stocked Trout Residency Study found that about 70 percent of the sites sampled had fair or better residency. That is, stocked trout residency was not a problem on most stocked streams. But at about 30 percent of the sites, a large percentage of the fish had migrated away from the stocked stream sections.
In streams where residency was a problem, the trout moved within about nine days after stocking. A higher percentage of trout remained in areas with favorable habitat: reliable food availability and protective cover including fallen logs, undercut bank and boulders. Water chemistry and fish size made no significant difference. Variances between hatchery water conditions and sample site waters on the days of electro-fishing had little impact on residency. And curiously, rainbow trout were more likely to stay near their stocking sites than browns.
“It is a little counter-intuitive that the rainbows were moving less,” said Detar, “but all trout have the ability to move. Native trout are generally moving around spawning time or in the summer and winter, but that’s different — they’re doing it as part of a natural cycle.”
Since 2006, the research has continued. In March, Fish and Boat biologists performed multiple electro-shock studies on stocked trout in Toms Run in Indiana County, Mountain Creek in Fayette and Kimberly Run in Somerset.
Detar said the decade of research into stocked trout residency is winding down, but it influenced Fish and Boat’s trout management strategy.
“We decided that 40 percent is the threshold,” he said. “If we’re finding those trout remaining in the stream section, we consider that stream to not have a residency problem.”
Because rainbow trout are more likely to stay put, more rainbows are stocked in the pre-season. Stream sections with low residency are now stocked closer to opening day, or in season.
“If we could stock every water a week before opening day, we’d do it,” said Detar. “The challenge is we only have a finite number of stocking trucks and personnel.”
Also, the launch of Approved Trout Waters Open to Year-Round Fishing regulations was partially influenced by trout residency. On rivers so designated, that have trout residency problems, the new regs favor stocking closer to opening day.
Detar said the research offers clear insight for anglers.
“I don’t know if there’s one right answer on how to find them. In general, stream sections with better habitat — log jams, undercut banks — have better stocked trout residency,” he said. “The best thing we can do is distribute fish throughout a section. We want them to spread out, but we want them to stay in that system. It provides for maximizing the angling opportunity in that stream.”
Anglers who suspect that a stocked stream section may have a trout residency problem can report it on the Fish and Boat website at the Fishing Hole page, http://fishandboat.com/inform.htm.