YONKERS, N.Y. (CBSNewYork) – It’s springtime, which for many means baseball games, a picnic in the park or maybe catching some rays in the sun.

But for some, this season is all about catching eels, right in the Hudson River.

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It’s all for a good cause.

Wading into a murky marsh along the Hudson River, volunteers dig and search deep inside woven nets for teeny, tiny, transparent water creatures just an inch or two long: Baby glass eels.

“We probably have a good 50 eels in here, some fish mixed in, a couple of mummichogs,” said one volunteer.

The glass eels come as a small form of treasure for the volunteer researches at the Sarah Lawrence College site in Yonkers, reported CBS2’s Reena Roy.

“We will open up the net, count eels. It can vary from a few up to 700 eels,” said volunteer Jason Muller.

Several times a week each spring, they gather and analyze to provide vital findings for the Department of Environmental Conservation. It’s one of 14 sites across the state where hundreds of students and families have helped with research for more than a decade.

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“Try to study how many young eels come into different areas of the Hudson River in spring, which is their migration season,” said Sarah Mount of the Department of Environmental Conservation. “There’s still a lot we don’t know about eels, so when are they arriving, how many, and where is great starting information.”

The little guys travel here all the way from the Sargasso Sea near Puerto Rico. It takes them about a year to get to the Hudson River, where they’ll make themselves at home for up to three decades.

In recent years, numbers have been up, which likely means the water is healthy.

“Strong eel population is a good indicator of healthy environment in all those places,” Mount said.

“It’s really important research because this is an indicative species which tells us about health of other fish and animals of the river,” said Muller.

They’re weighed before they’re released back in the water, where they grou up to be about 3-4 feet long.

Meanwhile, new neighbors will soon join them next year, as their population in New York continues to grow.

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If you’d like to volunteer to help the research or to find out more, click here.