Staten Island’s eel population is in a cold plunge.

The year’s icier-than-normal winter has put a partial freeze on the city’s American eel migration, with nearly half of the wriggly and nearly-invisible critters making their annual pilgrimage from the ocean into Richmond Creek this season.

Just about 4,000 juvenile eels — referred to as “glass eels” at this point because they are almost see-through — have been collected at the estuary as part of the state’s annual eel count, which invites students to wade in the waters, count the fish by hand and learn about the lesser-known city slickers.

“I learn about the eels’ life span and how they move around, and it’s pretty fun looking at the eels, but sometimes it makes me want to throw up!” admitted Oginga Thompson, 12, a sixth-grader at William A. Morris Intermediate School 61, saying the eels look “disgusting.

“My favorite part is having fun and stuff and not being in school,” the kid said.

On Thursday, the boy and his fellow students plucked just seven glass eels from their net, which is the lowest total they’ve tallied since they started their weekly outside-class sessions last month.

Richmond Creek is one of the last stops the eels make on their 2,000-mile journey from their birthplace in the Sargasso Sea just south of the Bahamas, and their populations are considered “depleted” by the Atlantic States Marine Fisheries Commission.

Earlier expeditions in the migration season — which ranges from January through May — yielded as many as 165 eels in a single visit.

Ecologists said the drop was expected as the season draws to a close.

Still, the overall count is on track to be a far cry from the nearly 11,000 American eels that were tallied in Richmond Creek last year.

But Megan Edic, a city research scientist at the city’s Department of Environmental Protection, noted that the tallies vary from year-to-year but are generally robust overall.

“It’s not a cause for concern!” she insisted of this year’s seemingly paltry count.

“American eels are doing pretty good. Since the program started in 2008, the [state Department of Conservation] has counted over a million eels across the state, so it’s pretty amazing,” Edic said.

“We get thousands of eels every year. The population is not in the clear — they’ve lost a lot of habitat — but we’re happy we’re seeing as many as we are.”

This year’s colder-than-average winter — and the monster snow dump that landed on the Big Apple — could have plunged thousands of the eels into a state of torpor, or dormancy, where the fish slow down their metabolic systems and bury themselves in the mud.

It would take multiple years of lower tallies for ecologists to be concerned about the glass eel population, Edic said.

Fortunately, plenty are still passing through Richmond Creek for students to catch, tally and release.

The sun was shining strongly enough Thursday for the students to see some of the eels swimming around their waders.

“I was just walking, the water was clear, and I saw something swimming by!” exclaimed Jordy Minchala, 11, who loves the program because “I get to learn about more things that are in water and how they live.”

Donovan Lee, 11, said that spotting a glass eel is easy if you know where to look.

“It’s exciting!” the child said.