Wildlife and the Changing Seasons

12/13/2010

This week's guest post is from Catherine Schmitt, author of Maine SeaGrant's Coastal Companion. Below is an excerpt from the "December" section of the book, which reveals what the fish are busy doing as winter progresses in the coastal environment.

December

 

As the temperature of the ocean drops, some fish move offshore to deeper waters where the temperature does not fluctuate, and others move inshore to shallow waters that warm in the pale winter sun. The winter skate moves into shallow areas of gravel or sandy bottom, from Canada to North Carolina. Winter skate is one of seven species of skates occuring along the North Atlantic coast (the others are the barndoor, clearnose, little, rosette, smooth, and thorny). Winter skates (Leucoraja ocellata) are large animals that can live up to 20 years. Skates are responsible for mermaid’s purses—the hard, black, leathery egg cases with long horns on each corner that wash up on the beach like so many tiny sleds entangled in dried rockweed strands.

Another fish only just arriving is the Atlantic tomcod (Microgadus tomcod). The tomcod ranges in coastal nearshore waters from Labrador and Newfoundland to Virginia, preferring the mouths of brackish streams, estuaries, and muddy harbors. Tomcod are also known as frostfish, because they run up rivers to spawn during the frosty months of December through February. They feed mostly on small crustaceans (especially shrimp and amphipods), worms, small mollusks, squids, and juvenile fish. The anadromous (sea-run) tomcod lives in the chilly shadow of its more famous marine kin, the cod.

At six to eight inches long, rainbow smelt are the smallest of Maine's anadromous fish, and now they are moving into estuaries where they will spend the winter. Ice shacks may appear on the ice above them, as fishermen begin this traditional winter harvest of Osmerus mordax. Come spring, the smelt will chase the thaw upstream to spawn in freshwater rivers. Smelt feed on zooplankton, shrimp, worms, and small fish; they in turn are eaten by striped bass, bluefish, and birds. They travel in schools in shallow water less than a mile from shore. Commercial landings of smelt peaked in 1966 at 360,000 pounds, with the majority being landed from Maine waters.

Pollock begin spawning in shallow waters of the Gulf of Maine, especially along Jeffrey's Ledge and the eastern slope of Stellwagen Bank, at the mouth of Massachusetts Bay, and north to Isle of Shoals and Casco Bay. The young pollock (Pollachius virens) that are born in the winter sea will disperse throughout the Atlantic, from the Gulf of St. Lawrence to New Jersey, occasionally as far south as North Carolina. The name of the Passamaquoddy tribe of Native Americans means "those who pursue the pollock," and their tribal home of Passamaquoddy Bay between Maine and Canada is the "pollock-plenty-place." The pollock is deep olive-green with a silvery white belly and a sharp silver line running down each side. Also called Boston bluefish, saithe, coalfish, or green cod, the pollock is an important food fish caught in the same nets as cod and haddock. While it is often grouped with these "groundfish," pollock live anywhere from rocky bottoms to near the ocean surface, and they will gather by the hundreds in great schools. Pollock are voracious eaters, hungry for small fish, shrimp, and other crustaceans. As they move closer to shore for spawning this time of year, they are more frequently caught, and are a favored target of sport fishermen. Oceanographer Henry Bigelow noted their capacity to fight, and that they will take an artificial fly (“silver body with white wings of hackle or hair is good, especially with a touch of red”) or bite on clams or small baitfish.

Like the tomcod and winter skate, the smooth flounder (Liopsetta putnami) breeds in estuaries in winter, a habit that earned it the nickname of Christmas flounder. Perhaps these fish have evolved to release their eggs during the cold winter months to give their offspring a jumpstart on life.


Follow fascinating, funny, tragic or otherwise compelling and timely stories about animals, as chosen by our editors and writers, including Daily Treat blogger, Janet McCulley.
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