Fate of stocked trout: 5 things learned from 4-year study (No. 5)

Editor’s Note: This is the the final 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.

AZGFD Sport Fish Biologist Zach Beard contributed to these posts.

5. Fish within a few days of a stocking

Maybe you’ve heard it over and over: Fish right after a stocking. Well, this study showed that’s a prime strategy.

We conducted analyses to look at how an angler’s catch rate would be affected by several factors:

• The number of trout stocked.
• The number of days since the last stocking event.
• Other characteristics of our anglers such as tackle type.

From this analysis, we found that factors such as the number of days since the last stocking event and preferred gear type did influence angler catch rates.

For one, the probability that an angler catches at least one trout decreases significantly as the number of days since the last stocking increases. This means that your best chance to catch a trout is during the first few days after stocking. Not to say fish aren’t still in the stream — they just might be a bit harder to catch.

So this, then, is a big takeaway for anglers from these 5 things we learned? If you want to catch more stocked trout, focus your efforts fishing near a stocking location in the days shortly following a stocking event. After that, don’t be afraid to fish spots along the stream margins like undercut banks, and under overhanging vegetation or boulders. These are the places that fish go to as they distribute in the stream and become more selective.

How to fish right after a stocking event

So you didn’t see the stocking truck roll by? Or you missed our #WheresHatch live videos on our “Fish AZ” Facebook page that show one of our hatchery trucks hauling in a fresh batch of fish?

No worries.

We have plenty of resources to help you fish around a stocking date. Stocking schedules are available.

But even better, our I Support Wildlife memberships include up-to-date stocking information.

Finally, visit this site often for all kinds of fishing information, including our “Reel Deal” statewide reports that mention the weekly stockings.

Of course, nothing beats time on the water.

Thanks to our employees and volunteers for their countless hours of labor on this project, and the many anglers who caught fish and reported tag information.

This study will help us provide better fishing for generations to come!

Missed the entire list?

Here’s a recap:

1. Most trout don’t survive past one week of being stocked

Soon after they’re stocked, the fish are being caught. Anglers: It seems you’re doing a great job of fishing AZ.

First, some facts during the duration of the study:

• Biologists implanted 492 trout with radio transmitters (246 rainbow trout and 246 Apache trout).
• Many of the trout — 60 percent — are no longer alive after one week in the streams.
• It was several weeks before the percent of trout remaining from a single stocking was below 20 percent.

This is why most streams on our stocking schedules call for waters to be stocked every 1-2 weeks, keeping trout in these “intensive use” systems to maintain opportunity.

Yet there are rare exceptions. In one stream, 71 percent of radio tagged trout remained alive after one week. Surprising?

Get this: The longest surviving trout was a pair of Apache trout (Fish Nos. 1C and 38C) that were still alive 123 days after they were stocked when we detected them on Dec. 4, 2015 in the East Fork of the Black River. Who’s up for the challenge of catching these hard-nosed Apaches?

Anglers were not the only ones eating stocked trout. Birds and mammals, such as ospreys, great blue herons, and raccoons, consumed between 6 to 30 percent of radio tagged trout.

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.

“There could be several possible explanations for this behavior,” said AZGFD Sport Fish Research Biologist Zach Beard regarding the trout’s lack of 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. Fish “1C”’s longest recorded journey was 49 meters downstream. Fish 38C wandered about 150 meters downstream and 186 meters upstream. Both Apache trout, featured earlier in the No. 5 “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.

3. Anglers spend tons of time fishing for stocked trout!

If fishing a high country stream in Arizona is a therapeutic experience, and we believe it is, then anglers who fished during these surveys should have an advantage in the mental health department. Anglers have spent thousands of hours casting lines and catching fish on these scenic stretches of stream.

Depending on the stream, anglers each year spent around 3,600-13,800 hours fishing and caught around 1,900-14,300 trout.

In general, anglers kept a large proportion of the stocked rainbow and Apache trout.

Return-to-creel rates are estimates of the percent of fish stocked that were ultimately caught and kept by fisherman. These rates are used by managers to measure how good a fishery is performing. In most of our stocked trout streams, our goal is for as many trout as possible to be harvested by anglers.

Our state’s return-to-creel rates are similar to those from other streams all around the country. We estimate that usually greater than 25 percent our fish stocked were harvested by anglers. Nationwide, most stream fisheries stocked with trout generally have return-to-creel rates of between 30 and 40 percent.

Canyon Creek had the best return-to-creel rate at 66 percent in 2014 — higher than most return-to-creel studies documented in the entire nation.

4. Current stocking amounts satisfy anglers

Do extreme amounts of stocked fish equal anglers catching bag limits? Well, stocking amounts are perhaps not as important as some have thought.

For example, during the study, we varied the amount of trout stocked in a stream. Some streams received a big increase and some were cut in half. Our analysis showed the probability of catching a trout only increased by 3 percent (from 50 to 53) even when stocking numbers went up substantially. This takes into account all the other factors that go into catching a fish.

We of course want to maximize angler satisfaction. Our current stocking numbers seem to keep catch rates satisfactory. Increasing the number of trout stocked may not increase catch rates in these streams. Our hatcheries are at maximum capacity for producing fish (in 2013 we were 100,000 pounds short of the amounts of stocked fish our managers requested). And so studies like these are important in helping us spread stockings throughout the state in the most efficient ways possible.

Fortunately, the majority of anglers were typically happy with memories made on our mountain streams.

Results from our study also indicated:

• Factors such as an angler’s catch rate, age, and the tackle they used (bait, flies, or lures) influenced an angler’s satisfaction with their fishing experience.
• In general, anglers 50 years of age and older were less satisfied with their fishing experience at lower catch rates than younger anglers.
• Additionally, anglers who used multiple gears types on the same trip (bait, flies, and lures) were less satisfied with their fishing experience compared to anglers using a single tackle type.