Saving Seafood

Biologists Have Recorded The Loudest Known Fish And Oh Boy

December 21, 2017 — Each year between February and June, the fish gather to spawn in Mexico’s Colorado River Delta. The fish, a type of croaker called the Gulf corvina, meet in water as cloudy as chocolate milk. It’s a reunion for the entire species, all members of which reproduce within a dozen-mile stretch of the delta.

When the time is right, a few days before the new or full moons, the male fish begin to sing. To humans, the sound is machine guns going off just below the waterline. To female fish, the rapid burr-burr-burr is a Bing Crosby croon. Make that Bing cranked up to 11.

Marine biologists who recorded the sound describe the animals as the “loudest fish ever documented,” said Timothy J. Rowell, at the Scripps Institution of Oceanography in California. Rowell and Brad E. Erisman, a University of Texas at Austin fisheries scientist, spent four days in 2014 snooping on the fish with sonar and underwater microphones. The land surrounding the delta is desolate, Rowell said. Fresh water that once fed wild greenery has been diverted to faucets and hoses.

But the delta is alive with the sound of fish. “When you arrive at the channels of the delta, you can hear it in the air even while the engine is running on the boat,” Rowell said. Sound is measured differently in water than in air; still, the fish are as loud as lawn mowers, Rowell said.

Read the full story from the Washington Post at Science Alert

 

Rhode Island: Narragansett Bay’s Ecology Changes Worry Fishermen

December 11, 2017 — NARRAGANSETT, R.I. — Narragansett Bay has experienced dramatic changes during the past century, from being a dumping place for sewage and industrial pollutants to a near paradise for recreational swimming and boating. But changes continue to occur, whether from the warming climate, invasive species, fluctuating wastewater effluent, or other factors.

As University of Rhode Island oceanography professor Candace Oviatt recently told an audience of fishermen, scientists and students, “I don’t think I’ve ever seen an average day on Narragansett Bay. The bay is always changing. Every year is different. Whether we like it or not, the bay is going to keep changing.”

Oviatt’s comments on Dec. 6 were part of a daylong symposium sponsored by Rhode Island Sea Grant and aimed at creating a dialogue between fishermen — many of whom are worried that the bay has gotten so clean that there is little food left for fish to eat — and scientists whose research tells a sometimes confusing story of how the bay’s changing ecology might give that erroneous impression.

While most of the scientists claim their research suggests that the biomass of fish and other creatures living in Narragansett Bay has changed little through the years, almost all said the composition of species that call the bay home has changed dramatically.

A weekly fish trawl survey in two locations in the bay conducted since 1959 illustrates those changes. According to Jeremy Collie, the URI oceanography professor who directs the trawl, in the early years of the survey most of the species collected in the nets were fish and invertebrates that live on or near the bottom, such as lobster, winter flounder, tautog, cunner and hake. Those species also happen to prefer cooler water.

In recent years, the species that prefer warmer waters and that live higher in the water column have dominated the trawl surveys, including butterfish, scup and squid.

Read the full story at ecoRI