This Saturday, May 30, you are invited to join us on World Fish Migration Day. Hosted by scientists and educators at multiple locations along the lower Hudson River Estuary, this event celebrates the vital role played by estuaries in the life cycle of many of our ocean fish species who migrate as part their reproduction ritual, moving between the ocean and connected estuaries in a carefully timed rhythm.
Estuaries are perfect nurseries, full of abundant food and shelter for newly spawned fish, allowing them to grow and mature before they migrate into deeper ocean waters. Within estuaries, there are a variety of habitats including marshes, mudflats and small backwater channels, which provide ample food and protection for a wide variety of species, enhancing their chances of survival due to reduced predation and competition for resources. Without estuaries, biodiversity in our oceans would suffer greatly.
What makes the Hudson Estuary special?
The Hudson River Estuary provides some of the most critical spawning habitat along the entire Eastern Seaboard, supporting multiple young of the year fish (those hatched during the calendar year) including several migratory species. Often referred to as the “long arm of the sea,” the Hudson Estuary stretches a full 153 miles from where it leaves the ocean until it ends at the Troy dam just past Albany, providing important habitat for multiple spawning fish species. The estuary’s lengthy configuration results from it being a fjord carved by meltwater from the ice during the last ice age. Over this long stretch, the water changes from deep marine saltwater to shallower slightly salty brackish areas and then to freshwater where it links to tidal wetlands. It is home to many species—from the small flatfish called a hogchoker to the feisty blue crab.
From salt to fresh
For our anadromous fish species (those born in freshwater), the movement from the ocean to freshwater to spawn and back is arduous. The shifting environment forces the fish to fully adjust their physiology and morphology, which requires a lot of energy. Hudson iconic migratory species include river herring, American shad and striped bass and the federally endangered Atlantic sturgeon, who enter into the river at this time of year to spawn, heading to the freshwater section of the upper estuary; their timing is triggered by the changing water temperatures of spring. Once, these “river runs” would be met with eager fishermen casting out nets for the annual shad run, or harvesting Atlantic sturgeon, pulling in striped bass by the dozens. While those days may be gone, the Hudson remains a critical place for this annual anadromous spawning ritual.
From fresh to salt
The Hudson also welcomes one catadromous species as part of our annual migration celebration. Catadromous species spend most of their adulthood in freshwater but migrate to the ocean to spawn and lay their eggs. The American eel is one such reverse migrator. They spend their entire life in freshwater before moving thousands of miles into the ocean to spawn and die, launching their small planktonic embryo into the currents to travel back to their natal rivers. At this time of year, we are welcoming thousands of tiny year-old glass eel as they migrate into the Hudson and move up into the Hudson tributaries to spend the next few decades before feeling that reproductive tug to return to the Sargasso Sea.
What have we seen?
World Fish Migration Day is a global celebration of migratory species that begins late in May and stretches into early June, to celebrate the journeys and spread awareness about the importance of estuaries and rivers worldwide. Over the past decade Lamont-Doherty Earth Observatory, which is part of the Columbia Climate School, has joined with the NYS Department of Environmental Conservation and the Hudson River National Estuarine Research Reserve in coordinating with multiple environmental organizations to host a local event focused on our Hudson Estuary. Throughout that time, we have netted 9,676 fish from 50 different species from the broader 235 species that have been identified in the mainstem Hudson River Estuary by New York State researchers. This is incredible for a single-day event in just the lower part of the estuary. Some of our more abundant species have been small feeder fish that have recently spawned, like the silvery Atlantic silverside and bay anchovy. Other top numbers include mummichog, a small killifish with males that sport a bright yellow belly during mating season, and Atlantic menhaden, who spawn just outside the mouth of the Hudson and then the young of year move into the Hudson to take advantage of the food and shelter. We have also pulled in lined seahorse and northern stargazers, catches that thrill the attendees. Check here to see the full range of what we have caught over the years.
Our World Fish Migration Lower Hudson & Harbor Fish Count celebrates these migratory species entering the Hudson River Estuary. There are public fishing events where participants can help pull a seine net to get a glimpse at some of these iconic species—or simply cheer us on and help with fish identification using simple tools we provide. Lamont will be hosting an event at our Hudson River Field Station (200 Ferry Rd, Piermont NY) from 12 to 4 p.m. as part of this celebration. There are several other sites distributed throughout the lower Hudson and NYC area, so you don’t have to travel far to be a part of this annual ritual. For full information about places and times for specific events please visit the event website.
Additional Resources:
- World Fish Migration Lower Hudson & Harbor Fish Count
- Hudson River Field Station
- NOAA Fisheries
- New York State DEC Hudson River Estuary Program
Margie Turrin is director of educational field programs at Lamont-Doherty Earth Observatory and director of the Hudson River Field Station. She develops and runs projects that focus on community engagement and understanding our Earth and environment.
Marisa Annunziato is education and outreach coordinator at Lamont, where she organizes and runs science education projects for all ages. She holds a marine science degree and enjoys connecting the public to the Hudson River through education and community science programs.
