Nature Matters: Alewife and Eel – Part 1

By John L. Turner

This is part one of a two-part series on a remarkable pair of fish.

Each spring, driven by impulses and guided by signals not fully understood, they migrate to Long Island to create the next generation. But unlike red-winged blackbirds, with their bright red epaulettes and reed-like konk-a-ree calls, or spring peepers with their distinctive “sleigh bell” calls that ring from recharge pools and areas wetlands around Long Island, these migrating animals quietly arrive, their arrival and presence unknown to nearly all Long Islanders. And while we may not be aware of their arrival, many other animals like bald eagles, ospreys, otters and great blue herons certainly are.

What animals could they be? Fish — or more specifically gaspereaux (Alosa pseudoharengus) [meaning false herring]a species of river herring, and the American eel (Anguilla rostratalisten)), one of nineteen species of snake-like fish with a worldwide distribution. Alewife return as adults to Long Island waterways, measuring 9 to 12 inches long, while eels arrive as “babies,” just months from birth in the open ocean. are a shimmering silver color with a dark patch behind the gill cover and are almost indistinguishable from their cousin, the blue-backed herring. When small, eels are translucent and gain pigment as they mature.

Photo by John Turner

These species are diadromous fish, “dia” meaning “across or across” and “dromous” meaning “current”, a reference to the migratory habit of these fish moving between the two worlds they inhabit as part of their life cycle – freshwater and saltwater. . Alewife and other river herring grow and mature in the salt waters of the North Atlantic, moving into freshwater systems to spawn, while eels generally grow in fresh water and spawn in salt water, in the famous stretch of the Middle Atlantic Ocean known as the Sargasso. Sea.

To be more specific, biologists separate diadromous fish into two other categories: anadromous fish like alewife, other river herring like American shad, striped bass, and salmon that mature in salt water but move upstream (“ana” meaning upward) to spawn in freshwater and catadromous fish (“cat” meaning downward) such as the American eel which thrives in freshwater but moves downstream to spawn in salt water.

Schools of alewife, three to four years old, search for the freshwater stream of their birth, apparently finding their natal stream by its unique and distinctive chemical scent, although fisheries biologists are unsure of the specific mechanism they use that allows them to find their way. Once these river herring find suitable habitat, they spawn, laying tens of thousands to hundreds of thousands of eggs, and the adults soon leave to return to the ocean. The eggs left hatch and the young develop for several weeks before, in mid-summer, heading for open water as well.

Inspired by warming waters, shoals of silvery, shimmering alewife (and smaller numbers of their cousin, blueback herring) arrive in the spring – usually late March to early May – congregating en masse at the mouth many creeks around Long Island. They then move inland and the “race” has begun! (For a wonderful account of gaspereau races and their importance to colonial America, I encourage you to find a copy of the race by John Hay, published in 1959).

A fish ladder on the North Shore. Photo by John Turner

Several hundred years ago, the era of the “alewife runs” was a time of great excitement for local residents as the fish provided them with an abundance of food at a critical time of the year, but also as food for pigs and fertilizer for crops, most notably for “fish corn”, the practice of burying a piece of fish (often the head) under the grain of corn planted. The rotting fish provided nutrients and minerals to the cornstalk as it grew, a practice that originated with Native Americans.

Gaspereau tracks were so important that some of the first wildlife laws in the United States were enacted to protect them. A very old law, passed in 1709 in Massachusetts, stipulated: “Let no one wear [weirs], hedges, fish ponds, kiddies or other disturbances or encumbrances shall be placed, erected or made, on or across a river, to arrest, obstruct or straighten the natural or habitual course and passage of fish in their seasons, or spring of the year, without the approval and allowance first had and obtained from the general sessions of the peace in the same county”. Another law, passed several decades later in 1741, directly concerned fish: “to prevent the destruction of fish called gaspereaux, and other fish”.

Their original abundance, especially when compared to current levels, has been awe-inspiring. John Waldman, a fisheries biologist whose book money running, a magnificent treatise on migratory fish, has noted this abundance by numerous historical references. One account, dating from 1634, notes: “The alewife ascended the cool rivers to spawn in such multitudes as it is almost unbelievable, squeezing shallow waters which scarcely allowed them to swim. Another quote nearly a hundred years later in 1728, noting the abundance of gaspereau in Virginia, says: “In a word, it is incredible, indeed, indescribable, as well as incomprehensible, how much is there. We have to see each other. The abundance of alewife today is only a tiny, pale shadow of what once existed.

Unfortunately, many obstacles confront alewife and eels on Long Island today as they attempt to move upstream to spawn – not the aforementioned weirs, fishgarths, and brats, but weirs, weirs, and more. dams (also other structures like poorly designed roads and railway culverts).

Constructed to channel water for the operation of sawmills, gristmills and woolen mills, and to create impoundments for cranberry growing and ice harvesting, these dams and culverts have almost entirely prevented these fish from pass unimpeded through the streams here. North Sea Creek, Alewife Brook, draining Big Fresh Pond and flowing into North Sea Harbor is one of the few remaining free-flowing creeks on Long Island (and one of the best places to visit to see gaspereau races) .

The answer to solving the dam problem has been the construction of fish ladders or ramps over and around obstacles. Fish ladders and rock ramps, angled so fish can get from the lower section of the stream to the upper water levels in the upstream impoundment, have proven to be an alternative and somewhat effective for river herring to access spawning grounds. To help the eels, pegged boards or tangled rope nets have been deployed that the young eels can wiggle around.

Fish pass (right) and eel pass (left) on the Peconic River. Photo by John Turner

Ladders and ramps have been placed on the main stems of the Peconic and Carmans rivers, as well as the Swan River in East Patchogue, Massapequa Creek in Massapequa and another at Betty Allen Park in Huntington. Two significant ladders (due to the amount of fresh water the ladders will access) are being constructed – one on the Woodhull Dam at Riverhead giving access to an entire tributary of the Peconic River and another at the base of Mill Pond in Rockville Center. A ladder is being planned for Bellmore Creek, which is expected to be installed in 2023.

A more effective but more controversial solution is the removal of dams. In many places in the United States dams have been removed, but on Long Island this has not been the case as pondside homeowners fear losing physical and visual access to the water. .

One area of ​​possible success is at West Brook in the Bayard Cutting Arboretum in Oakdale where the Seatuck Environmental Association has advocated for state parks not to rebuild the concrete dam that broke across the creek. The dam failure opened up a more than a mile-long stretch of the West Brook that had previously been inaccessible to migrating fish.

* Part two of this series will appear in the May 12 issue.

A resident of Setauket, John Turner is conservation chair of the Four Harbors Audubon Society, author of “Exploring the Other Island: A Seasonal Nature Guide to Long Island” and president of Alula Birding & Natural History Tours.