Warming waters lure new species

NORWALK — In the lab above Copps Island Oysters, the small room overlooking the harbor is filled with the sounds of bubbling jugs of algae and humming fish tanks. In one tank, a skillet fish sucked on the glass and a small silver cunner swam to and fro; in the other, a black sea bass lurked sulkily in the corner, a black mottled pattern that had emerged since its capture camouflaging with the rock print covering the back of the tank.

According to Dick Harris, of Copps Island Oysters, all are fish that prefer warmer waters, which have contributed to the shifting demographics of Norwalk’s waters.

“What we’re seeing now is a transition,” he said, “cold-water fish going out and warm-water fish coming in.”

The warm-water favoring cunner fish, once greatly outnumbered by other types of fish in Norwalk Harbor, was the most frequently seen fish in the recently released 2017 Harbor Health Study. In contrast, winter flounder, which fishermen could once catch by the dozen, are in sharp decline.

With the changes in fish have come changes in other wildlife. Harris said big schools of bunker, a silver-spotted fish with an expression of perpetual surprise, have come into the harbor, bringing with them cormorants and osprey.

Harris has long been interested in marine ecosystems. While working for Shell Oil, he pursued a degree in marine science and spent his weekends learning and visiting the marshes. There, he witnessed the interplay between various species — the fiddler crabs digging holes into the sediment that allowed water to get to the roots of the marsh grass, and silky fibers mussels used to fasten themselves to the bank, holding shore together.

“The whole thing forms a network,” he said.

Erik Trautmann / Hearst Connecticut Media Dick Harris, of Copps Island Oysters, speaks at his lab in Norwalk about the decline and rise of species due to warming waters.