Saving Seafood

How Ultra-Black Fish Disappear in the Deepest Seas

July 16, 2020 — Alexander Davis admits that he can be a glutton for punishment. He staked part of his Ph.D. on finding some of the world’s best-camouflaged fishes in the ocean’s deepest depths. These animals are so keen on not being found that they’ve evolved the ability to absorb more than 99.9 percent of the light that hits their skin.

To locate and study these so-called ultra-black fishes, Mr. Davis, a biologist at Duke University, said he relied largely on the luck of the draw. “We basically just drop nets and see what we get,” he said. “You never know what you’re going to pull up.”

When he and his colleagues did cash in, they cashed in big. In a paper published Thursday in Current Biology, they report snaring the first documented ultra-black animals in the ocean, and some of the darkest creatures ever found: 16 types of deep-sea fish that are so black, they manifest as permanent silhouettes — light-devouring voids that almost seem to shred the fabric of space-time.

“It’s like looking at a black hole,” Mr. Davis said.

To qualify as ultra-black, a substance has to reflect less than 0.5 percent of the light that hits it. Some birds of paradise manage this, beaming back as little as 0.05 percent, as do certain types of butterflies (0.06 percent) and spiders (0.35 percent). A feat of engineering allowed humans to best them all with synthetic materials, some of which reflect only 0.045 percent of incoming light. (“Black” paper, on the other hand, returns a whopping 10 percent of the light it meets.)

Read the full story at The New York Times

Gloucester Times: So, be nice to your oceans

August 1, 2018 — This is why we can’t have nice things. Because we’re human and we tend, over time, to spoil most of the wondrous things we touch. You need only look at big league baseball, which, despite the historic season unfolding for the local nine, has become a soulless slog through the barren desert of analytics, home runs, strikeouts and pitching changes.

And then there are the oceans. We’ve really left our smudgy fingerprints all over them.

According to a new study that offers the most exhaustive mapping of the Earth’s ocean wilds, there is virtually no corner of the planet’s oceans that has not suffered human disruptions or the ill effects of human-created climate change.

“Nowhere is safe,” James Watson, an author on the study published in the journal, Current Biology, told The Washington Post via a video abstract of the study.

Perhaps more alarming, the study calculates that only 13 percent of the planet’s oceans could still be classified as “wilderness” because of the unceasing onslaught of humans trekking around the planet.

Read the full editorial at the Gloucester Times

 

Old fish are rare in today’s heavily fished oceans

“More age complexity among species can contribute to the overall stability of a community,” researcher Lewis Barnett said

September 15, 2017 — Catching an old fish has become an increasingly rare and difficult task in today’s oceans. New research suggests fishing pressure around the globe has depleted stocks of older fish.

The findings — detailed this week in the journal Current Biology — are worrisome, as the longer fish live, the more chances they have to reproduce and replenish a species’ stock.

“From our perspective, having a broad age structure provides more chances at getting that right combination of when and where to reproduce,” Lewis Barnett, a postdoctoral researcher at the University of Washington, said in a news release.

Scientists analyzed the numbers of older fish among 63 populations across five ocean regions. They found older fish had suffered significant declines in a vast majority of the studied populations. For roughly a third of fish populating, declines among older fish measured a magnitude of more than 90 percent.

Read the full story at UPI

How a Fish That Hatches in Coral Reefs Finds Its Way Home

December 28, 2016 — The larvae of fish that live in coral reefs are tiny, and they are not very good swimmers. They are pushed by currents away from the reefs on which they were hatched for days or weeks until they learn to swim. Then, somehow, around 60 percent of them make their way back to their birthplaces, where they spend the rest of their lives.

Scientists know that they can navigate using the position of the sun by day. But they find their way at night, too, and now researchers think they know how: They are magnetic.

Researchers studied the larvae of Doederlein’s cardinalfish, Ostorhinchus doederleini, a reef fish that grows to about five inches long. They collected specimens near One Tree Island in the Great Barrier Reef, off the northeast coast of Australia.

When the larvae hatch, currents carry them north-northwest, and experiments have shown that they consistently swim south-southeast guided by the sun back to their birthplace. But to see whether magnetic forces are also at work, the researchers tested them by using a device that creates a uniform magnetic field whose direction can be manipulated.

With the larvae in a tank surrounded by the device, the scientists turned the earth’s normal magnetic north 120 degrees clockwise. The fish followed right along, swimming in the direction the researchers steered them. The study is online in Current Biology.

Read the full story at The New York Times