River Herring: Keystone Species Crumbling
by Fishermen's Voice staff

Commercial landings show an overall decline beginning in 1975. Foreign factory ships brought on an Atlantic herring collapse at that time. Midwater trawlers came in the 1990s. Catch figures before 1950 are too spotty to be valuable. Maine DMR chart

Rockland, March 1. At the Maine Fishermen’s Forum scientists presented data showing the once economically valuable and biologically essential river herring or alewife, in a steep decline. The decline recorded over the last 30 years is on top of an already reduced stock. There are no reliable records on the stock before an earlier decline about 150 years ago.

Commercial landings of river herring show an overall decline since 1975. Efforts to reintroduce river herring to Massachusetts waters have met with little success. The (Atlantic States Marine Fisheries Commission) has proposed a range of approaches to dealing with the problem. They range from a moratorium on commercial harvest; to reducing effort and by-catch; to a river specific approach with by-catch reporting.

Not long ago the river herring was known to everyone in coastal New England and fished by many New Englanders. The river herring, historically known as the alewife, was easy to catch. No boat, hooks and line or risk from being at sea required. Nearly everyone ate them, either fresh or smoked.

These alewives, about 12 inches long and close cousins of the Atlantic herring, poured by the hundreds of millions into New England rivers to spawn in lakes and ponds. When they did, the bottoms of Maine’s rivers and streams could not be seen for the backs of alewives packed together on their way home to spawn.

Maine Department of Marine Resources biologist Nate Gray sees this more recent decline as a composite of “several stressors on the alewives.” Loss of habitat, hydropower dams, overfishing, beaver dams, predators and pollutants are on the list. When the fish get to a dam they swim around looking for a way past. They are running on a fixed budget of fat reserves. Being jammed at the foot of a dam burns that reserve. Survival rates are effected by the number of obstacles these fish encounter.

Gray describes them as “purpose built, they eat small stuff (plankton), bringing nutrients up the food chain. We eat cows, but we cannot eat grass. We need cows to make nutrients accessible to us.” In the same way the herring is vital to the marine food chain above it. It is a keystone species. “The management focus has been on apex species,” said Gray, the fish at the top of the pyramid, cod, haddock, stripers, etc., but they are all dependant on the herring below them. The stocks of river herring and Atlantic herring, and the habitats they depend on, need to be prioritized before the species above them can recover.

After leaving the rivers they remain inshore. When the waters cool, they follow the plankton they feed on, some as far as South Carolina. They return to the river in four years to spawn. Living eight or nine years, they can spawn more than once.

At a few inches long, the juveniles decide it is time to head back to sea and pour downstream by the billions. Then it is time for the other fish of the Gulf of Maine to eat. Cod, haddock and other groundfish gorged themselves on this feast, growing large, fast. Since the lobster industry got started in the late 1800’s alewives have been used as bait.

‘Not long ago’ is used here in relative terms. This cycle of spawning in ponds, and feeding humans, fish and other wildlife on the way in and out, went on for thousands of years. Native Americans fished them., Colonial New Englanders also took advantage of fish that swam to their doorsteps. This particular ’not long ago’ was the mid-1800’s, before most of the access to the lakes and ponds of Maine were blocked by various dams on the rivers.

Millions of years of repeating the process fine-tuned it. About the right amount of fish in, to have healthy well fed juveniles on the way out. But by 1900 that all changed. Alewives continued to travel up stream to spawn in some ponds, but pre-industrial numbers can only be guessed at. The records are spotty before 1950, and they are all, for the most part, from the towns that sold permits to harvest alewives for a fee. Today there are 42 Maine towns with permits, but only 14 are active. Some, for the sake of conservation, do not harvest alewives from their towns rivers.

There had to have been a massive drop in the amount of alewives after the dams were built. Currently a further massive plunge in alewife populations (3.5 million pounds to 100,000 pounds) in New England rivers has lobstermen, ground fishermen and scientists more than a little concerned.