A History of Herring, Fish Ladders and our Herring Run

This article, written by Dr. Kathleen Brady, appeared in the July 30, 2021 edition of the Chronicle. It has been slightly updated to reflect a year later.

Each spring, anadromous fish, like the alewife and blueback herring, collectively called river herring, migrate from salt water up a river to fresh water to spawn. Anadromous fish spend most of their lives at sea but return to fresh water to spawn. Diadromous fish migrate between fresh and salt water, and include both anadromous fish and catadromous fish that spend most of their adult lives in fresh water, but must return to the sea to spawn.  Anadromous fish – herring - hatch in fresh water, where they remain until the late summer or fall, when they are mature enough to swim downstream to where salt and fresh water mix. Gradually they make their way to the ocean and meet up with other migrating herring along the East Coast. When they are 3-5 years old and about 10-12 inches long, they heed the call to return to the place where they were born.

In Massachusetts, alewives spawn in late March to mid-May, when the water temperature hits 51 degrees F. Females lay about 60,000 to 350,000 eggs. Depending on the water temperature, their eggs hatch in three to six days. The adults that survive the stressful spawning process swim back to the ocean, recuperate, and prepare for their next arduous spawning season. Relatively few young herring survive to return to spawn, as most get eaten. River herring can swim more than 10,000 miles upstream from the Atlantic Ocean to lay eggs in freshwater lakes with ample food and few predators. But the path to the ponds and lakes is an arduous one. River herring don't jump like salmon as they move upstream, but they swim fast enough in short bursts to pass through the rapids and fish ladders. Alewives prefer to lay their eggs at night in slow-moving water; blueback herring prefer deep, swift freshwater rivers with hard substrates.

 Herring must evade swarms of ravenous gulls, osprey, and an array of other hungry creatures such as turtles and muskrats! In April of 2022, the Centerville River had thousands of herring returning to spawn. The Cape is one of the premier locations herring seek in April and May.

What are Fish Ladders?

 Dams, locks and other manmade constructs (like narrow culverts) create barriers. A fish ladder is an inclined series of tiny waterfalls that create an alternate stream for the fish. These ladders mimic the natural flow of a river and allow fish to swim or to leap relatively low steps to the other side of a dam. If the fish ladders are too steep, volunteers are known to have carried fish over the dams, helping thousands of river herring complete their migration pattern. The velocity of the water falling over the steps must be great enough to attract the fish to the ladder, but it cannot be so great that it washes fish back downstream or exhausts them to the point of inability to continue their journey upriver.

 Written reports of rough fish ways date to 17th century France, where bundles of branches were used to create steps in steep channels to bypass obstructions. Over several hundred years, there have been multiple designs for fish ladders, baffles, and elevators. The effectiveness of fish ladders depends on the design as well as the fish species' swimming ability, and how the fish move up and downstream. Regulatory agencies face a difficult task to match hydrodynamic measurements and swimming performance.

The Lake Elizabeth Dam and Fish Ladder

Our fish dam and fish ladder are in dire need of replacement. The failure of the dam and our seasonal droughts are among the main reasons our water level is so low. In the season in 2022, our herring run monitors, counting 4 times a day for 10 minutes each time for 10 weeks, counted just 3 herring attempting to return to our Great Pond. Long Pond in Barnstable had thousands of herring returning. There are many making the journey not far from us.  Our goal is to rebuild the dam and fish ladder and restore a robust herring run to our ponds.

Kathleen Brady, M.D.

Former President and Ex Officio Board Member

Red Lily Pond Project Association