Native species ill-equipped to take on ‘bucket-stocked’ fish

Over the past several months, you’ve seen the terms “illegal introduction” and “bucket stocking” in this space on several occasions.

After once such mention – during which I tossed around a few moderately inflammatory adjectives describing the folks who would commit such acts – a reader called me to task for skipping a bigger issue.

His point, in part:

“In [your column], you use such words as ‘illegal,’ ‘troubling,’ ‘sickening,’ and ‘selfish’ to describe illegal stocking and the people who do it. But please understand that a fairly large proportion of your readers will read ‘Northern Pike in Pushaw’ and say: ‘Great! Wonderful! Let’s Go Fishing!’

“The critical information missing from the article is, why is it wrong, and when you say, ‘regardless of its effects,’ just exactly what are the possible effects? Perhaps a quote by a fisheries expert would help readers understand why they should NOT be happy.”

In this business it’s pretty easy to stop thinking of columns as singular events, and begin to view them as a pieces of a larger, hopefully entertaining, series.

Of course, that’s not really the case. Each piece should be able to stand on its own. And though I’d dealt with a few of the “why” and “why not” questions before, the reader made a great point: Another refresher course on fisheries biology would have fit in well in the column that dealt with illegal pike in Pushaw Lake.

I quickly e-mailed one of the best “fish guys” I know (though, I’ve got to say, the state is full of them). Paul Johnson is a longtime regional fisheries biologist in Greenville for the Department of Inland Fisheries and Wildlife. I asked for help. The outspoken Johnson kindly obliged.

One basic point Johnson made in a follow-up interview rang true, and I’ll share it with you here.

“Additions [of a species] are always ‘in replace of’ [existing fish],” Johnson said. “They are never ‘in addition to.'”

Here is his response, in which he fleshes out that point quite nicely:

“Maine waters are limited in their ability (potential) to produce fish, especially compared to other areas in the U.S. and Canada. That’s because of Maine’s bedrock geology and soils, where the nutrients to begin the food chain originate, and the climate,” he wrote.

“Adding a new species to a water will not add to the pounds of fish produced there. Pounds of fish already there will be replaced by the introduced species if they successfully establish.

“Fish that are replaced by an introduction are those that are most vulnerable to the effects of competition (the ability to compete for the basic requirements of life – most especially food and space) and/or the effects of predation. If the introduced species is a large predator that eats other fish, all native fish that live in their space stand a chance of being eaten. Big predators eat lots of other fish!

“Our native Maine species, especially the brook trout, and to a lesser extent the landlocked salmon, have evolved since glaciation (that’s over the past 12,500+ years) in the absence of competition and predation from species like yellow perch, white perch, bass, pike, muskies, crappies, etc., ad nauseam. Those other species did not make their way into Maine waters after the ice left the area, and brook trout and salmon did and have thrived in their absence. But add other species, and see what happens.

“Where, for instance, is there a good brook trout fishery in Maine where there is an established population of white perch? Look how the brook trout fisheries in the Rangeleys and in Moosehead were compromised by yellow perch in the early ’50’s and early ’60’s. (Yellow perch are more competitors than predators, think what bass will do! Or add pike to the mix.)

“New introductions affect not only the body of water where they occur, but as the introduced species increases in abundance, over time it can – and will – move to every other body of water in the drainage downstream to the ocean, and upstream to the first barrier to movement, either a falls or dam.

“How many miles of river, and how many lakes and ponds, and what kind of other fish populations stand to be affected by the pike in Pushaw Pond?

“Because of fish passage up the Penobscot and Piscataquis, we could in time even see pike upstream as far as Blanchard. Is that what the perpetrators wanted?

“Because of this, I consider illegal introductions of fish acts of biological terrorism!”

Thank you, Paul. I hope the answer is as enlightening for you as it was for me.

Coming up on Thursday, I’ll finally tell you about Ruth Jewell and the monstrous doe (yes, I said doe) she shot recently.

I’ve been sitting on the story for a week or so, waiting for the photos to be developed. I assure you, it’s been worth the wait.

John Holyoke can be reached at jholyoke@bangordailynews.net or by calling 990-8214 or 1-800-310-8600.