Fate of stocked trout: 5 things learned from 4-year study (No. 2)
Editor’s Note: This is the second of five “things we learned” from our 4-year study to investigate the fate of rainbow trout and Apache trout stocked into several of Arizona’s popular stream trout fisheries.
As part of this project, AZGFD biologists conducted nearly 5,000 angler interviews on six different streams (Canyon Creek, East Fork Black River, East Verde River, Silver Creek, Tonto Creek, and West Fork Little Colorado River) during the trout stocking seasons (April to September) of 2013–2016. From these interviews, biologists estimated total harvest (number of stocked trout kept by anglers), angler effort (total time spent fishing by anglers), and angler catch rates. Our biologists also implanted trout with radio transmitters in order to track their movements and determine how long they survived in the streams.
Check back each day this week as we reveal the entire list. AZGFD’s Zach Beard, Ryan Mann and Andy Clark contributed to these posts.
2. Trout don’t move far from release locations
A stocked rainbow trout, it seems, is not exactly a wandering Nemo.
Radio-tagged trout did not move far from release locations — typically less than 200 yards. In fact, many of the fish we stocked were caught from the pools in which they were stocked. More good news for anglers, because, of course, you don’t have to move far to find fish.
Here’s a tip of the day: We found that many fish tend to wander slightly away from deeper pools of an exact stocking location and seek refuge in oddball places like undercut banks, boulders, or overhanging structures. This was often only about 15 yards or less from a stocking point. So naturally, anglers also should consider targeting these structures once a stocking day has passed.
Here’s an example of one of our biologists detecting the position – and, in turn, fate or movement — of a tagged trout, part of the technology of telemetry.
There could be several possible explanations for this behavior,” said AZGFD Sport Fish Research Biologist Zach Beard regarding the trout’s minimal movement.
“It may just be a natural trout behavior. Several studies have documented that wild stream trout often spend the majority of their lives in a relatively small portion of the stream. It could also be a remnant of the hatchery conditions trout are raised in. Trout stocked in Arizona streams spend their entire time in a relatively short raceway of a hatchery, which doesn’t allow them to move more than a few hundred feet. As such, they may grow accustomed to remaining in a relatively small area.”
Even some of our longest surviving fish did not move very far from where they were stocked.
For example:
- Fish “1C”’s longest recorded journey was 49 meters downstream. Fish 38C wandered about 150 meters downstream and 186 meters upstream.
- Both 1C and 38C, Apache trout featured earlier in the No. 1 “thing we learned”, had survived 123 days at the time of our last survey before the winter of 2015. The batteries in our radio tags typically die after 200 days, and so these fish could no longer be tracked. Yet they could still be alive.
- And then there’s the exception (one of 492 radio-tagged trout). During a nine-day trek in 2015, Fish No. 41, a rainbow trout, propelled itself 12.3 kilometers downstream on the East Verde River before finding a home. Yet it was caught and harvested a couple weeks later.
This, for better or worse, is a snapshot of a stocker trout’s life.
Check back tomorrow for No. 3.
See No. 1: “Most trout don’t survive past 1 week of being stocked”
