The Deerfield River Trout Spawning Study, Part 2

The Deerfield River Watershed Trout Unlimited chapter (DRWTU) recently conducted a scientific and volunteer-based survey that found spawning brown trout in the main stem of the upper Deerfield River.

This means that there could indeed be wild brown trout in the river.  This invaluable resource is being taken for granted by some, but others are doing what they can to ensure a healthy river habitat that supports the Deerfield River ecosystem and the multiple tourism-based businesses that rely on this magnificent river.

Learn more about it in this three-part series (Part 1 is here).


Earlier this year, on the feast day of St. Patrick, I found myself in some pretty unforgiving frigid weather on the upper Deerfield River. Turning into the wind, I braced myself for the next 60+mph gust that bored through the river valley.

On a regular trip to the Deerfield, this pause would have ended with a hasty cast of a Hare’s Ear, Slump Buster or some other amalgam of wire and thread to beat Ol’ Man Winter before he caught his breath. Instead, I took a rake and went to town on an old brown trout spawning redd.

Along with several other interested anglers-turned-citizen-scientists, I had decided to brave the cold on this bright and blustery mid-March day to see how many redds still contained viable eggs from the fall.

The Deerfield River Trout Unlimited chapter (DRWTU), along with the support of various agency scientists and local businesses, had found the first evidence of wild-trout spawning below the hydro-electric Fife Brook Dam (read about that in Part 1, here) a few months earlier during the fall.

Volunteers braving the cold for the spawning study (pc: Kevin Parsons)

The DRWTU had collected eggs from several redds they discovered, so that they could be scientifically identified. Those eggs were sent to the National Genomics Center for Wildlife and Fish Conservation, run by the United States Forest Service in Montana. This research station was able to use DNA extraction methods to positively identify the species from 25 different redds.

The good news? Twenty-three redds contained brown trout eggs and the other two contained rainbow trout eggs. Although DRWTU had secured evidence that trout were trying to reproduce, nobody knew if any of these eggs had survived over the winter. Issues like daily hydro-peaking, and dewatering and stranding of redds during low flows from Brookfield Power’s Fife Brook Dam could lead to subsequent exposure and freezing.

And, that brings me back to why I was digging up some redds on such a cold day. I was raking the gravel in the redd’s tail-out section, while a second fisherman, wearing calf-birthing gloves to protect himself from the bitterly cold water, pushed slightly-flowing water towards our survey nets to scoop up any eggs we were able to uncover.

Several old redds were a bust; nothing to be found, which was quite discouraging. A couple redds produced eggs that had clearly gone bad: milky white eggs that had crumpled to a wrinkle of their former selves.

It was by pure luck my small team decided to rake one more time at what looked like the end of a redd. We found a literal mother-load of still viable translucent eggs, some with a pair of eyes formed in the center. It was a real lesson to see those tiny globes float in the water and into our net. It certainly made me a firm believer in Antron-style egg flies, and, of course, in the work we were doing.

Just a normal morning at the river, wearing your birthing gloves and searching for eggs (pc: Kevin Parsons)

Although this was all really exciting, we now had a problem. Because we had found viable eggs, we were worried. Unlike trout and salmon eggs, which can survive periods of time out of water (which we just provided our own evidence of what was already known), alevins and fry have a nearly 0% survival rate for air exposure for even as low as an hour (Becker et al. 1982). Redds are regularly being de-watered at low flows in the Deerfield River, and alevins that hatch during those times are simply not going to have a good time of it.

 

There is also the possibility that any alevins that survive in redds that happen to be wet when they hatch, could be pulled into the current during the sudden pulses that Brookfield Power’s Fife Brook Dam carries out.

When caught in the wide open, the alevins likely have little chance to make it back to cover and can be swept away (Crisp & Hurley 1991) in the sudden current (Crisp & Hurley 1991), reducing their overall survival rate, as a hydo-electric operation does not represent the flow regime of a natural river (Poff et al. 1997).

One study found that the highest flow-related mortality for alevins and fry of brown trout, on freestone rivers, happens during spring floods (Jensen & Johnsen 2002). Now, think about the river flow pulses that happen daily on the Deerfield….

We still had to prove that those eggs were viable, with tiny complete embryos, but we did not have long to wait. Those very eggs we had just found actually hatched in our vials before we even drove them back to lab. They did the hard part for us.

This proved that trout are successfully reproducing in the Deerfield River, but now we need to figure out how many eggs on average are surviving to alevins and, then, how many of those little guys are making it to catch-able size. This will be a long process and will take multiple stakeholders to carry out, but there is good news on the horizon.

The sac fry recently hatched from the Deerfield River, the product of successful wild brown trout spawning

N.B.:
The Trout Spawning Study was created to help prove that Deerfield River brown trout are struggling to reproduce due to the hydro-peaking conditions caused by daily fluctuations of Brookfield Power’s Fife Brook Dam and Bear Swamp operations.

Brookfield Power’s operating license is up for renewal before the Federal Energy Regulatory Commission (FERC). DRWTU needed scientific evidence that trout were, indeed, successfully spawning but that hydro-peaking conditions were curtailing the trout’s efforts.

Digging up redds, even for science, can bring criticism. But, there were few known ways to determine if the Deerfield’s redds contained eggs that survived. Scientific protocols for egg extraction are non-existent.

Knowing that there could be damage done, DRWTU wanted to make sure that damage was mitigated and consulted with agency scientists that developed protocols specifically for this study. This ensured that the least amount of redds was disturbed but still provided necessary evidence to support DRWTU’s claims.

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3 thoughts on “The Deerfield River Trout Spawning Study, Part 2

  1. Another great post, Joe!

    Also:

    1. I vote that St. Patrick should be the patron saint of Deerfield trout!

    2. In part 3, let us know what you’d like us to do? Is there a “call to action” that the blog readers can do (e.g., an online petition) to encourage FERC to mandate more even flows?

  2. This is really, really exciting! What a great bunch of volunteers and results! This study will really make a huge positive difference for the Deerfield in years to come. Look forward to part 3!

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