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Health & Fitness

What's That? (Anita Wright, GFEE)

Seine fishing is one of the most popular activities in our Summer Field Ecology programs and School Environmental Education field trips. For those of you unfamiliar with a seine, it is a fishing net that hangs vertically in the water with its bottom held down by weights. The net is dragged through the water, catching most creatures in its path.

There’s always a bunch of kids that would be perfectly happy seining for the entire day, and I can understand why. Each time the seine is pulled to shore, there’s an excitement as to what might have been caught this time around. Often, we catch the familiar mummichogs, silversides, sheepshead minnows, killifish, a few crabs and some mud snails. But sometimes, as we are letting the fish free, we see something unusual and ask, “What’s that?”

This is precisely what happened when we saw the mystery fish pictured above in a seine net we pulled during a field lesson at Accabonac Harbor with Springs School students in the T.E.R.N. program. We scoured our field guides, but nothing seemed to match. We took a photo of the fish in the observation tank before we set it free, and Steve sent the photo to our go-to-guy on fish identification, Howard Reisman, local college professor of Ichthyology.

In a day or so, Howard responded that we had caught a juvenile crevalle jack, Caranx hippos. They are often found throughout the Gulf of Mexico, especially along the coast of Texas and the west coast of Florida. So what was this creature doing in our estuary?

In his fascinating and informative book, Exploring the Other Island: A Seasonal Guide to Nature on Long Island, John Turner describes in detail about how this crevalle jack and other tropical fish end up in Long Island waters, mostly in the south shore bays.

In short, the eggs and even the larval stages of these tropical fish are swept up in the Gulf Stream and carried north. By the time they reach within 200 miles south of Long Island, they have grown large enough to swim on their own, and move into currents called warm- core rings. This brings them closer to shore, and then tidal surges and wind-driven currents bring them into our south shore bays. They usually arrive in the spring and feed in eelgrass beds, alongside the common fish we catch in our seine net. But come late fall, these tropical fish are doomed. As the waters turn colder, they will die or become weakened by the falling water temperatures and eaten by a predator.

According to Turner, there are “as many as several dozen species of beautiful tropical and subtropical fish” in Long Island’s estuaries. We hope our students and Field Ecology participants see some of these fish in our seine nets this spring, summer and fall!

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