The Great Fish Migration

These past few weeks I had the pleasure of working with the Somes-Meynell Wildlife Sanctuary teaching classes of Maine students about Alewife and American Eel Migration. Alewives and Eels are keystone species in Maine contributing to all levels of the ecosystem. I am from New York where we have a fish species extremely identical to Alewives called “Bunker” (Atlantic Menhaden). I was surprised to learn that Alewives and Bunker are different species yet occupy the exact same ecological niche. Because of my experience as an angler, I was able to contribute this unique perspective to the program.

Bunker

Pictured above is the Atlantic Menhaden (“bunker”) which migrates from the Chesapeake Bay in Virginia up to Massachusetts. Bunker is an anadromous species meaning that it lives most of its life in the oceans, only migrating to freshwater to spawn. Bunker shares similar morphology to Alewife in the form of a spot on its side, filter feeder mouth, forked tail, and size.

Alewife

Pictured above is the Alewife, a species of herring which has a similar migration cycle to bunker, spending most of their lives in the ocean, only migrating up rivers and estuaries to spawn. Alewives spawn in inland Maine and then migrate back down south into the Atlantic Ocean. For all intents and purposes, Alewives and Bunker are sister taxa serving the same ecological purpose and significance. As brutal as it sounds, their main ecological role is…being eaten. Alewives are a keystone species in Maine serving as a food source for Osprey, Bald Eagles, Cod, Lobsters, and Striped-Bass. Additionally, anglers fish for Alewives to use/sell as bait. Alewife migration into Maine is crucial for the survival of carnivorous/predatory species.

American Eel

Life Cycle

The American Eel pictured above has an extremely interesting life cycle. The Eels spawn in the Sargasso Sea, an area of warm water and seaweed off the coast of Florida caused by four ocean currents forming a gyrus. Newborn eels (leptocephalus) are flat and transparent, an evolutionary function enabling them to remain unseen by predators and traverse ocean currents. Leptocephalus morphs into Glass Eels that get picked up by the Gulf Stream current and carried 2,000 miles to the Gulf of Maine. By the time they reach the Gulf of Maine, they have transitioned to the Elver stage of development. The Elvers then make the journey into freshwater streams, rivers, and lakes where they will live most of their lives. After 20-30 years of development in freshwater, the eels reach sexual maturity and are ready to migrate back to the Sargasso Sea to spawn, and promptly die.

Significance

American Eels are a catadromous species meaning they migrate from the rivers to the sea to spawn (opposite of Alewives). In recent years, commercial price of Elvers has increased tenfold, going from $2oo per pound in the 1990’s to over $2,000 per pound currently. hence, the state of Maine only gives out 400 Elver fishing licenses per year. All Elver anglers all have a certain number of pounds they are allowed to catch. Anglers will have their license revoked if they do not follow all regulations. Human built dams have blocked Alewife and American Eel migration up-and-down stream. If nothing is done about the dams, then populations of Alewives and Eels will drastically decline, and therefore the whole ecosystem.

Mission

To aid the migration of Alewives and Eels, the Somes-Meynell Wildlife Sanctuary received funding to create four fish ladders. The ladders extend from Somes Sound (saltwater) to Somes Pond (freshwater) where Alewives will spawn, and eels will live. Alongside Billy, the head coordinator of Somes-Meynell, and Rusty, a commercial Elver fisherman, we gave interpretive talks about the importance of Alewives and Elvers to school children. The goal was to increase people’s awareness and understanding of migratory species, how humans have harmed them, and how we can now help them. We started off the field trips by giving brief overviews of the history of the dams, species, and ecological importances. Afterwards, we walked to the fish ladder where we opened the gate for Alewives to continue their migration in freshwater.

Fish Ladder

Here is the opening of the Somes Pond fish ladder allowing Alewives to travel between Somes Sound and Somes pond. Alewives have a keen sense of smell which helps them detect the exact body of water where they were born. Alewives will return multiple times throughout their lifespan to the same body of water to spawn. This is incredible considering they live in the ocean for 4 years before migrating back inland.

Hands on Learning

Here I am teaching a group of middle schoolers about Alewife morphology. I found that the kids were asking questions and seemed more engaged when they could physically see and feel the fish rather than hear about them. It was awesome to see their faces light up when they saw what we had been talking about.

Osprey

Several Ospreys live in close proximity to the fish ladder. Here you can see an Osprey diving down to check out the pen. These Osprey pick off Alewives like fish in a barrel (literally!).

Bald or Lazy Eagle?

This Bald Eagle would sit by the fish ladder and wait for an Osprey to catch Alewife. Once the Osprey would catch an Alewife the Eagle would chase him down and try to steal his catch!

Takeaways

It was rewarding being able to teach kids about the importance of fish as it is often forgotten. Sometimes we would have bad weather during these programs, but it didn’t stop the kids from enjoying the fish. I learned more about communicating scientific concepts in ways that children can comprehend. This is a skill that I can translate to my own Junior Angler program as most kids will be new to fishing. Connecting with Billy and Rusty was awesome, they know so much about the Maine fishery and conservation. I hope to work with them again one day on some of their projects.

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