June 27, 2007

A recent development relating to Connecticut River anadromous fish must have officials worried, and this issue has nothing to do with Atlantic salmon.

Yes, the salmon numbers are still pathetic. That’s a constant. But now there are storm clouds hovering over other marine species that migrate upriver annually to spawn, namely river herrings. The fact is that blueback herring and alewife have virtually disappeared from the river while American shad are greatly diminished. That could spell trouble on the horizon.

When criticized about disappointing salmon runs that have averaged around 200 over the past 40 years, restoration officials have tried in recent years to justify their program’s existence by pointing to the bountiful herring and shad runs brought about by major improvements in water quality and aquatic habitat. The small herrings have little or no value other than bait in the sportfishing community, but the recreational shad fishery is popular, drawing thousands of anglers annually. The current problem is that shad numbers have dropped from around a million annually to about 200,000, which is troubling. Do the math. Anglers with memories of fishing the Holyoke tailrace when 750,000 shad were lifted over that dam must notice a significant difference when a mere 170,000 are lifted there, and that’s been the case the past couple of years.

As an observer who’s followed the anadromous runs for nearly 30 consecutive years and fished often for shad during the 1980s, I noticed the plummeting numbers in the 90s and queried officials for answers. The most common explanation was that a striped-bass moratorium had greatly increased stocks of large, predatory stripers, a factor that could be directly related to diminishing river-herring numbers, including shad. But, frankly, that never made a lot of sense to a man who studies history, particularly New England and Connecticut Valley history. I think in the historical context, which pokes a gaping hole in the striped-bass-predation theory.

Haven’t river herrings and stripers always co-existed in the Connecticut River system? Weren’t there more large stripers and also more herring in the Connecticut River between the Contact Period and the Revolution than there are today? How, then, can we blame the disappearance of herrings on striped-bass predation? It defies logic.

Connecticut River Coordinator Janice Rowan says, “We have evidence that stripers are playing a role but questions remain about the size of that role.” So, in an attempt to answer that question, a study that began in 2005 is being conducted by University of Connecticut doctoral candidate Justin Davis and supervised by Associate Professor Eric Schultz, Department of Ecology and Evolutionary Science and co-director of the Environmental Science Program.

“We agree that (the declining-herring issue) is not likely to be a single-factor story,” wrote Schultz in an e-mail. “The ocean fishery for herring may be playing a role, but quantifying that impact will be difficult. Other predators may be important. Other threats that should be considered include warming trends in coastal waters, rainfall patterns, and increasing water withdrawals in coastal regions.”

Davis and a research team have been electrofishing for striped bass and using a stomach pump to examine their diet, while another crew has been tagging a releasing stripers that will be tracked and studied.

According the Schultz: “We will be putting together several sources of data in this way: gut contents of striped bass combined with data and assumptions about digestion rates, yield estimates of how many river herring a striped bass in the Connecticut eats in a season. Our tag-recapture experiment will yield estimates of abundance of bass in the Connecticut, so that we can estimate how many herring are consumed by stripers in the river in a season. Our final intent is to put this in a historical context so that we can estimate what portion of the herring decline is attributable to striped bass.”

Schultz called the predation issue “size-dependent,” explaining that the stripers most likely to eat river herring are at about the 28-inch legal minimum for a keeper. However, smaller “schoolies” are more than capable of devouring many shad progeny, which are now readily available to them and other predators, such as marine bluefish and indigenous freshwater species. But, again, the fact is that those predators have always been present in the Connecticut, so how much of an impact could they really be having on the current decline.

The answer, based on historical precedent, is probably not much. Seems more like a porous excuse for what sadly may be a doomed program.