Finally, spring has arrived! The days are longer, the bays have thawed, and most importantly, fish are on the move.
For thousands of years, alewives have returned every spring from their life in the open ocean to fulfill their primordial need to reproduce. In doing so, they have faced many natural perils along the way. In more recent history (shortly after the first European settlers arrived to the northeast), they have been confronted with a new set of challenges, ones that could potentially jeopardize the survival of their species.
The alewife is a species of fish that belongs to the herring family. They range from Nova Scotia to North Carolina, but can also be found living in landlocked lakes throughout the northeast where they have been intentionally introduced as a food fish or as bait. Due to their anadromous life cycle, alewives are often referred to as a river herring. An anadromous fish is one that spends its adult life in the ocean and returns to freshwater to spawn. Other examples of anadromous fish would be salmon, striped bass and sturgeon.
When water temperatures climb into the low forties, alewives begin their migration from the ocean to inshore bays, in search of the same river system that they originally hatched in some three to five years prior. It is believed that they are able to find their home river by using their sense of smell. By late March/early April they will have reached the mouth of local watersheds such as the Peconic River and will begin their ascent upstream when water temperatures approach fifty degrees. This leg of their voyage can be quite dangerous, as they must navigate through shallow waters, snags, and a gauntlet of predators, all while fasting.
Spawning takes place once they reach protected areas of the river such as lakes, ponds or quiet backwaters. A single female alewife can lay up to 100,000 eggs, which will be quickly fertilized by surrounding males. Unlike salmon, alewives do not die after they spawn. Rather, they return to their life in the ocean, hopefully to repeat the process the following year.
The now fertilized eggs sink to the bottom where they will adhere to any objects they come in contact with; plants, gravel, etc. Approximately six days later, the eggs hatch and the fry (baby alewives) will be less than a quarter inch in length. They will remain in the freshwater ecosystem for the entire summer, feeding on zooplankton and growing several inches in length.
As summer comes to an end, the young alewives will make their way downstream, entering the estuary by autumn. As water temperatures continue to drop, they will leave the protection of the estuary for the open ocean. They will spend the next three to five years in the ocean before returning to their home stream in order to pass their genes on to the next generation.
Throughout all stages of their life, alewives play a crucial role in both aquatic and terrestrial ecosystems as a forage fish. Forage fish are those organisms that are a primary food source for a wide variety of animals and their removal from the environment could have catastrophic consequences throughout the food web. Other forage species include; bunker, silversides, sand lance, squid and krill. A healthy alewife population greatly benefits striped bass, bluefish, cod, gulls, herons, osprey, eagles, seals, whales, dolphins, otters, and raccoons (just to name a few).
Unfortunately alewife populations are nowhere near historical levels. It had been reported that during colonial times that alewife runs were so massive, “You could walk across rivers on their backs.” They were an important food source for early settlers, especially since their flesh takes well to being cured with salt or smoke. Prior to a time of having refrigeration, this was an important quality for food to have. By the twentieth century, the demand for alewife shifted from use as a food fish to a highly sought after bait for the growing lobster industry. Even today, the primary bait used by lobstermen in Maine is the alewife.
Continued fishing pressure has negatively impacted alewife populations, resulting in tightened restrictions of their harvest. Locally they are a protected species and fishing for alewife, even if only for catch and release, is strictly prohibited. Although overfishing has played its role in the decline of alewife populations, the industrial revolution has had the greatest impact. The building of dams for power plants, irrigation, and flood control has blocked passage to crucial freshwater habitats. Not only was their access being denied, unregulated dumping of wastes into waterways was degraded water quality, which causes a dramatic decrease in the survival rates of larval fish.
In recent years, many of these negative impacts have been reversed. Small, unnecessary dams have been removed and restored to a natural state (like at Grangebel Park in Riverhead). Fish ladders have been installed on larger dams, allowing alewives to once again access upper lakes, ponds and headwaters. Tighter regulations regarding the discharge of waste, along with the cleanup of heavily polluted rivers has aided in the survival of larval fish.
Continuing these improvements to our waterways, along with better management of fish stocks will hopefully allow alewife runs to be a common occurrence for generations to come and continue to fuel the countless number of species that depend on them.
Places to Observe an Alewife Run
Grangebel Park, Riverhead
Woodhull Damn, Riverhead