I may be too stubborn to stop wearing shorts, but there’s no question that summer has ended in Pennsylvania. Tomorrow I’ll be headed to Loyalsock for my first day of fall sampling, and the third-to-last sampling event of my PhD (crazy). It’s been one wild ride, and the last day I drive out of Loyalsock is going to be a bittersweet exit. But, I have a few months before I need to think about that.
What’s on my mind today is the feedback that I’ve gotten from my post last week on stocking. Great discussions, great questions, and hopefully a few people that thought twice about their positions on trout stocking. Generally speaking, the vibe I get from most people is that they do support stocking programs, just not in Class-A wild trout streams. Some even go as far as to advocate for the end of stocking in all streams that support wild trout, regardless of abundance.
There’s nothing wrong with these views. In fact, my own opinions are casted with shades of this logic. They present a compromise- potentially a stocking protocol that could allow for increased recreational opportunities while still protecting wild trout.
Notice I say “potentially”? In ecology, everything is connected. And, when we do one thing to one stream, we can’t be certain that it will or won’t impact the streams around it. That’s what makes natural resource management a game of knowledge and know-how, but sometimes also a lot of luck. Mother Nature can be finicky. We can do math, study the science, and prescribe a certain management protocol and get the same result 99 times. And then the 100th time it fails. Hopefully it’s a contained failure with minimal loss, but other times the damage cascades throughout the ecosystem causing damage at levels. Not often, but sometimes.
So, we can limit stocking. We can even put a moratorium on stocking Class-A streams, or any other stream that holds a special designation. But, how much damage control does that really do? Seriously, I’m asking- I don’t know the answer.
The uncertainty comes from the fact that fish move. A lot. Particularly large, stocked fish that are spooked by their new surroundings when they are plopped down into a stream for the first time. In our dataset, we found evidence of hatchery introgression and fish straight off the hatchery truck at sites that are several miles from the closest stocking location. And, we routinely find a pulse of very large fish moving into smaller tributaries in June- the same time when water temperatures in larger waters get too warm. I can’t say that these are definitely hatchery fish, but I would bet money on it (and on a grad student salary, that says a lot).
So, my post today is just a cautionary tale. To protect and conserve waters, we can’t keep thinking of streams as individual units. Effective restoration of one stream often requires action to be taken on surrounding streams and on the landscape. Likewise, the effects of stocking will extend beyond the streams that fish are put in. Not stocking Class-A streams would be a great success for native trout conservation. But, if there is a stocking location in the next adjacent tributary, then the successes could still be minimal.
As long as we are stocking trout somewhere, there will still be some chance for negative effects to native populations. That isn’t meant to be a rally call for the end to hatcheries. It’s meant to be a warning that the solution isn’t quite as easy as “stock here, not there.” How far hatchery fish can spread is not certain, and it is going to vary depending on a lot of factors. When determining stocking locations, we need to think beyond the immediate radius of the release location. We need to consider what streams are within a few hundreds yards, to maybe even as far as a few miles. Could those stream be influenced by hatchery trout?
This brings up a bigger point, and that is nature is too variable for a “one size fits all” approach to management. It’s probably not advisable to advocate for a single management strategy to be deployed across an state. We need more emphasis on adaptive management- on adjusting management protocols in response to changing demands from humans, shifts in climate, and loss or gain of habitat. We need to use all the data available to us and make decisions. If we suspect that a certain management action is threatening trout populations, then it needs to be looked at a little closer and sooner rather than later.
It’s a daunting task, and certainly easier said than done. But, aren’t our natural resources worth it?