Fish on EARTH Magazine

Ocean circulation change suffocating Gulf of St. Lawrence

Fri, 21 Dec 2018 11:03:00 -0500

Research suggests that the Gulf Stream is shifting to the north, such that it's impinging on the flow of the Labrador Current near the Tail of the Grand Banks and reducing the supply of well-oxygenated water to the Gulf of St. Lawrence. Credit: K. Cantner, AGI.

Estuaries are among the most nutrient-rich and biologically productive areas of the ocean, and the Gulf of St. Lawrence, where freshwater from the Great Lakes and the St. Lawrence River meets the salty Atlantic Ocean in eastern Canada, is the largest estuary in the world. But the biodiversity and long-thriving fisheries of the Gulf of St. Lawrence could be threatened by declines in oxygen levels over the last half century. A new study suggests that a large-scale shift in Atlantic Ocean circulation is dumping warmer, oxygen-poor water into the gulf.

Spawning salmon engineer landscapes

Fri, 23 Feb 2018 11:16:59 -0500

Spawning sockeye salmon swim in a stream in Alaska. Credit: Katrina Mueller, U.S. Fish and Wildlife Service.

All animals depend on their ecosystems for habitat. And, in turn, many animals impact their ecosystems by engineering the landscape to suit their needs. Beavers provide an iconic example of ecosystem engineering when they build dams, which influence streams and wetlands. The engineering efforts of salmon, meanwhile, can even shape the bedrock of the watersheds in which they live, according to a recent study that modeled the evolution of those watersheds over several million years.

Evolution of eyes, not limbs, led fish onto land

Mon, 19 Jun 2017 13:08:40 -0400

Evolutionary advances in aquatic eyesight may have led vertebrates onto land. Credit: ©Callan Bentley, 2017.

In the Middle Devonian, roughly 385 million years ago, the first vertebrates began making their way out of water. For these pioneering fish, the adaptation of fins into limbs facilitated the transition. But in a new study, researchers have found that millions of years before fully functional terrestrial limbs evolved, some fish were developing better eyesight — an evolutionary adaptation they suggest gave an advantage to fish hunting insects near the shore.

The mackerel year: Tambora changed how New England fished

Wed, 17 May 2017 10:22:52 -0400

Fishermen clean mackerel near their saltwater farm on Deer Isle in Maine's Penobscot Bay in 1891. Mackerel fishing increased following the 1815 eruption of Tambora. Credit: NOAA Library, Silver Spring, Md.

The 1815 eruption of Indonesia’s Tambora Volcano led to a 1- to 1.5-degree-Celsius drop in the average global temperature, prompting 1816 to be called the “year without a summer.” New research analyzes weather data and historical records from New England to explain why, in the northeast U.S., 1816 was also called the “mackerel year.” As eruption-induced extreme weather triggered food scarcity in some areas, including a reduction in alewife numbers along the U.S. Atlantic coast, fishermen in the Gulf of Maine turned to mackerel fisheries farther offshore that had been neglected while more easily fished coastal and freshwater species were available.

Tiny fish illuminates tooth fairy mystery

Thu, 16 Feb 2017 11:01:35 -0500

When kids lose their milk teeth, the roots shrivel up and just the outer enamel falls out — a process known as basal resorption. Now, the discovery of a tiny jawbone from a 424-million-year-old fossil fish is shedding light on the origin of our modern mode of tooth replacement.

Coral Reef Roundup: December 2016

Tue, 15 Nov 2016 18:20:04 -0500

Reefs that lack large predatory fish have 50 percent fewer nutrients. Credit: Nicodemo Lentile.

With multiple threats facing our coral reefs — from climate change to overfishing — and scientists continually studying the coral reefs beneath the waves, new findings are announced often. Here are a few of the latest updates.

Tully monster mystery solved

Thu, 14 Jul 2016 13:52:44 -0400

In 1958, an amateur fossil collector named Francis Tully found a strange fossil in a quarry near Morris, Ill., southwest of Chicago. Thousands more of the worm-like Tullimonstrum gregarium, better known as the “Tully monster,” were recovered from the same deposit — now a National Historic Landmark called Mazon Creek fossil beds. But the creature’s full appearance and just what sort of animal the Tully monster was have remained mysteries. In a new study, researchers have now finally identified it as a jawless fish, similar to modern lampreys.

Jawless fish more like jawed fish than thought

Thu, 14 Jul 2016 10:25:04 -0400

Lamprey eels do not have jaws; instead, they feed with a sucking mouth lined with teeth. Credit: Joanna Gilkeson, USFWS Midwest, CC BY 2.0.

Vertebrates come in all shapes and sizes, but the one thing almost all have in common are jaws, which developed early in vertebrate evolution. Jawless fish, which evolved about 530 million years ago and are thought to be more primitive than their jawed relatives, are an exception. According to a new study, however, the brains of jawless fish have more in common with the brains of jawed vertebrates than previously thought.

Fish evolved quickly after earthquake

Thu, 21 Apr 2016 16:10:05 -0400

A male three-spined stickleback. Credit: Mark Currey.

Evolution is often thought of as occurring over very long timescales, but as a tiny Alaskan fish demonstrates, significant changes can take place in just a few generations.

Counting 'tree' rings in fish skulls provides climate clues

Fri, 29 May 2015 12:56:07 -0400

Most fish have little structures in their skulls that record growth patterns — periods of feast and famine — just like tree rings. Now, scientists are using these structures, called otoliths, to show how fish size may decrease as a result of a changing ocean.

Ice (Re) Cap: April 2015

Mon, 09 Mar 2015 12:17:20 -0400

From Antarctica to the Arctic; from polar caps, permafrost and glaciers to ocean-rafted sea ice; and from burly bears to cold-loving microbes, fascinating science is found in every nook and crevasse of Earth’s cryosphere, and new findings are announced often. Here are a few of the latest updates.

Down to Earth With: David Montgomery

Mon, 15 Dec 2014 13:31:56 -0500

From the length and breadth of his body of work, you might assume that David Montgomery, a geomorphologist at the University of Washington in Seattle, is approaching the end of a highly successful career. After all, among other accomplishments, he pioneered our understanding of how river channels shape landscapes, explored how glaciers and climate determine the height of the world’s highest mountain ranges, and helped elucidate how erosion has shaped human civilizations through time. He has authored or co-authored more than 140 academic papers as well as three (going on four) books, and even snagged a MacArthur “genius grant” in 2008. However, Montgomery is only a youthful 51 and shows no signs of slowing down — he even manages to find time to write songs, play guitar and sing in two Seattle-based bands, Big Dirt, a folk rock group, and High Noon, a bluesy jazz rock ensemble. Recently, EARTH’s Julia Rosen caught up with Montgomery before he headed off to Africa for another season of fieldwork.

Ancient shark jaws resemble those of modern fish

Tue, 19 Aug 2014 11:37:21 -0400

The well-preserved fossil of Ozarcus mapesae from two different lateral views. Credit: AMNH/F. Ippolito.

Sharks are thought to have one of the most consistent body plans in the animal kingdom; the formidable predators seem to have remained roughly the same for more than 400 million years. But a new study, published in Nature, suggests that sharks are not the unchanging, “living fossils” that paleontologists once thought.