State of the Planet

News from the Columbia Climate School

Join Us on June 10 to Celebrate World Fish Migration Day on the Hudson Estuary

Participants gather for fish count
Scientists and educators are at each site to share information about each species pulled in.

As winter turns to spring each year, the change in seasons drives migratory fish from the world’s ocean into estuaries and freshwater tributaries to spawn. The slight warming of the water, the subtle lengthening of the daylight, and simple biologic triggers can send an assortment of saltwater fish inland to reproduce. We celebrate this seasonal cycle on the Hudson River with our annual World Fish Migration Day Event hosted by the Columbia Climate School’s Lamont-Doherty Earth Observatory and the New York State Department of Environmental Conservation.

On Saturday, June 10, at multiple locations throughout the Hudson and Harbor, groups will host free public events inviting participants a chance to pull a seine net along the shore, or drop in a fishing line from a pier, to see just what might be moving in the water. We will host a site at the Lamont Field Station at 200 Ferry Rd. in Piermont NY. This will be our first Science Saturday event of the summer season. All the species are counted and then returned to the estuary to continue their role in the ecosystem. This event is a great way to celebrate National Ocean Month and to learn why the Hudson estuary is referred to as a vital ‘arm of the ocean’!

Why Do Fish Chose Estuaries for Spawning?

The ocean is a vast space with a wide mix of predatory species of fish, and small, young of the year fish, can find this a very hostile environment. The calm, protected waters of an estuary can provide juvenile fish a place to ‘hide out’ and, put on a little size, before they move back into the larger ocean and a more challenging environment. It is the connection between land and water, where the slowing of the water allows suspended materials rich in minerals and nutrients that wash in off the land to drop and settle, that creates valuable nurseries for many of our fish species. In addition to being calm, the shallow, nutrient-rich nature of estuaries offer a seemingly endless supply of food for young, freshly spawned fish. In the U.S., most of the fish we eat spend at least part of their lifecycle in estuaries.

What Species Could We See?

American eel
American eel are a common presence in the Hudson although at this time of year we are more likely to net smaller glass eel moving into the estuary or young elvers moving upriver, rather than this full grown yellow eel. (Image by Margie Turrin)

It is hard to predict what we might pull in. We regularly see striped bass, American eel, and a variety of herring species including the blueback, alewife (together referred to as river herring), American shad and Atlantic menhaden. There are also other species moving from fresh to salt water within the Hudson this time of year, like the iconic blue crab. Mating and egg release occurs in the saltier lower Hudson but the small crabs will travel to brackish (mix of salt and fresh) water to begin their cycle of shell creation and molting as they begin their growth to maturity. The males will spend most of their time in the brackish and freshwater sections of the Hudson before returning downriver to the salt to find the females, and mate again.

Sea horse
In the New York Harbor, lined seahorse are not an uncommon catch on World Fish Migration Day. This one has wrapped its tail tightly around the thumb of the sampler for stability. (Image by Edita O’Brien)

In addition to the estuary’s migratory fish species, we will also tally a wide array of other fish species like the lined sea horse, northern pipefish, bay anchovy, striped killifish, mummichog, striped mullet and many others. Every location will vary in the fish they find moving through the water, but at each site, a team of scientists and educators will be available to help you enjoy the event.

Northern Pipefish
Northern Pipefish are related to the lined seahorse, and are commonly pulled into our
nets, but their slim size allows them to easily slip through if not collected quickly for the count. (Image by Peter Park)

Where and When Will This be Happening?

There will be 11 events hosted in the Lower estuary that will run at the times and locations noted on the graphic below. For an interactive map and complete information on locations and times, please visit our event website. This is a wonderful partnership event with each site hosted by different organizations.

Fish Count Sites

What About Atlantic Sturgeon?

The majestic Atlantic sturgeon are also entering the Hudson at this time of year. Moving in along the river bottom, these iconic fish are heading to the Upper estuary to spawn. While we will not be seeing these fish in our Saturday catch tally, we are tracking this amazing species with another tool, eDNA. Hudson River Park in NYC, The Center for the Urban River at Beczak in Yonkers, Lamont’s Piermont Field Station team, and the Hudson River Estuary Program at Norrie Point are partnering for the third year in tracking a set of migratory species as they move through the estuary using environmental DNA or eDNA. Through analyzing water samples for small snips of DNA that the fish shed as they move through the estuary, we can track Atlantic sturgeon moving by our sections of the river. Samples collected in May showed sections of their DNA in the water in Piermont and Norrie Point as they moved from the Atlantic ocean to the freshwater Upper Hudson to spawn.

Atlantic Sturgeon
New York State DEC samples the sturgeon moving into the estuary to track their health and numbers. The fish are weighed, measured and sampled and then immediately returned to the water.

The eDNA program is only one way of tracking Atlantic sturgeon in the Hudson. In addition, the NYS DEC monitors their movement and their health while they are in the river, through a rigorous sampling program that you can read more about here.

Why Are Oceans Important in Migration and Beyond?


Respecting and protecting the world’s ocean is critical. World Fish Migration Day would not occur without our connection to the ocean. Humans are dependent on the ocean for so many ‘services.’ The word ‘services’ implies extractive use, and while many may object to it, understanding the importance of the ocean to us as humans is critical in establishing our respect, and enlisting our action to better care for it.

Who Can We Contact With Questions?

For more information on this event please contact:
Margie Turrin or Marisa Annunziato at Lamont-Doherty Earth Observatory.

Full fish and catch data from prior year’s events.

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