Eastern Atlantic Bluefin Tuna Threatened
An analysis of eastern Atlantic bluefin tuna trade data released Oct. 18 shows that harvests of the imperiled tuna are more than double the legal amount. This calls into question the National Marine Fisheries Service’s (NMFS) June decision, responding to a Center for Biological Diversity petition, that found bluefin were not endangered as long as there is a high degree of compliance with total allowable catch levels.
“Illegal fishing is rapidly pushing eastern Atlantic bluefin tuna to the brink of extinction. Rather than turn a blind eye to this ongoing crisis, the fisheries service needs to give this dwindling species the protection it needs to survive,” said Catherine Kilduff, a center staff attorney. “Endangered Species Act protections are necessary to stop U.S. imports from the Mediterranean and begin rebuilding this population, crucial to the health of the Atlantic Ocean and our fisheries.”
The Pew Environment Group report found that in 2010, the amount traded on the global market was 141 percent above allowable catch levels (32,564.9 metric tons). That doesn’t include black market bluefin missing from trade records. Discounting illegal fishing, the NMFS denial of listing for the bluefin determined that a 5 percent probability of extinction in 20 years is a reasonable threshold for endangered status. At catch levels of 30,000 metric tons, there is an 8.5 percent probability that less than 500 adult bluefin tuna will survive in 2030.
Highly migratory, warm-blooded fish, Atlantic bluefin tuna include two genetically distinct populations, one that spawns in the Mediterranean (the eastern Atlantic stock) and a much smaller population that spawns in the Gulf of Mexico (the western Atlantic stock). New analysis of the eastern Atlantic stock has implications for both stocks because of cross-Atlantic mixing. Capable of speeds higher than 55 mph, bluefin tuna from the Mediterranean traverse the ocean in a matter of weeks as early as age one. Overfishing means that fewer Mediterranean tuna reach U.S. waters.
“Skyrocketing consumer demand for bluefin tuna has driven overfishing and lax enforcement of international agreements,” said Kilduff. “After years of recognizing the problem, but not implementing a solution, the international community must ban trade until bluefin tuna populations rebuild.”
In August 2011 the center requested that the U.S. propose Atlantic bluefin tuna for protection under Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the major international treaty on endangered species. CITES protection would ban cross-border trade in Atlantic bluefin, potentially improving compliance with catch limits. The next CITES meeting will occur in 2013.
In response to the decline of the bluefin, the center last year launched a nationwide boycott of bluefin tuna (visit bluefinboycott.org for more information). More than 25,000 people have joined the center’s campaign and pledged not to eat at restaurants serving bluefin tuna. Dozens of chefs and owners of seafood and sushi restaurants have pledged not to sell bluefin.
According to a McKinsey & Company report released last month, current bluefin harvesting levels are projected to drive the eastern Atlantic fishery to collapse between 2012 and 2015. If illegal and unreported fishing could be 100 percent eliminated, the fishery could recover by 2023. But impressively, if the fishery were to be completely closed, according to the report, it would recover within eight years.
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For more information about the center’s campaign to save the Atlantic bluefin tuna, click here.
The Center for Biological Diversity is a national, nonprofit conservation organization with more than 320,000 members and online activists dedicated to the protection of endangered species and wild places.
The ghoulishly named ogre-faced spider can "hear" with its legs and use that ability to catch insects flying behind it, the study published in Current Biology Thursday concluded.
"Spiders are sensitive to airborne sound," Cornell professor emeritus Dr. Charles Walcott, who was not involved with the study, told the Cornell Chronicle. "That's the big message really."
The net-casting, ogre-faced spider (Deinopis spinosa) has a unique hunting strategy, as study coauthor Cornell University postdoctoral researcher Jay Stafstrom explained in a video.
They hunt only at night using a special kind of web: an A-shaped frame made from non-sticky silk that supports a fuzzy rectangle that they hold with their front forelegs and use to trap prey.
They do this in two ways. In a maneuver called a "forward strike," they pounce down on prey moving beneath them on the ground. This is enabled by their large eyes — the biggest of any spider. These eyes give them 2,000 times the night vision that we have, Science explained.
But the spiders can also perform a move called the "backward strike," Stafstrom explained, in which they reach their legs behind them and catch insects flying through the air.
"So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They're accurate," coauthor Ronald Hoy, the D & D Joslovitz Merksamer Professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences, told the Cornell Chronicle.
What the researchers wanted to understand was how the spiders could tell what was moving behind them when they have no ears.
It isn't a question of peripheral vision. In a 2016 study, the same team blindfolded the spiders and sent them out to hunt, Science explained. This prevented the spiders from making their forward strikes, but they were still able to catch prey using the backwards strike. The researchers thought the spiders were "hearing" their prey with the sensors on the tips of their legs. All spiders have these sensors, but scientists had previously thought they were only able to detect vibrations through surfaces, not sounds in the air.
To test how well the ogre-faced spiders could actually hear, the researchers conducted a two-part experiment.
First, they inserted electrodes into removed spider legs and into the brains of intact spiders. They put the spiders and the legs into a vibration-proof booth and played sounds from two meters (approximately 6.5 feet) away. The spiders and the legs responded to sounds from 100 hertz to 10,000 hertz.
Next, they played the five sounds that had triggered the biggest response to 25 spiders in the wild and 51 spiders in the lab. More than half the spiders did the "backward strike" move when they heard sounds that have a lower frequency similar to insect wing beats. When the higher frequency sounds were played, the spiders did not move. This suggests the higher frequencies may mimic the sounds of predators like birds.
University of Cincinnati spider behavioral ecologist George Uetz told Science that the results were a "surprise" that indicated science has much to learn about spiders as a whole. Because all spiders have these receptors on their legs, it is possible that all spiders can hear. This theory was first put forward by Walcott 60 years ago, but was dismissed at the time, according to the Cornell Chronicle. But studies of other spiders have turned up further evidence since. A 2016 study found that a kind of jumping spider can pick up sonic vibrations in the air.
"We don't know diddly about spiders," Uetz told Science. "They are much more complex than people ever thought they were."
Learning more provides scientists with an opportunity to study their sensory abilities in order to improve technology like bio-sensors, directional microphones and visual processing algorithms, Stafstrom told CNN.
"The point is any understudied, underappreciated group has fascinating lives, even a yucky spider, and we can learn something from it," he told CNN.
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