Likewise, would it be better if every ounce of life that came up on a trawler on Georges Bank were taken to the dock and turned into food, fish meal, fertilizer, etc? Or is it the lesser of two evils to at least leave some of that biomass in the system as food for scavengers, detritivores, etc? Do the albatrosses that are occasionally hooked by longline gear end up better off because of longlining (because they can feed on dead fish hanging from the gear all day long, not to mention the offal thrown overboard)? It's a big, nasty, complicated picture. I wonder if, on the whole, there's anything beneficial to the oceans about removing an entire shark versus removing just 5% of a shark. But that perspective seems to ignore the effect of putting biomass back into the system that you've plucked it from. On the gut level, and also when thinking about how many people on Earth are malnourished, the practice of shark finning seems abominable because of the apparent wastefulness of it. It's the kind of stuff that Michael Pollan might get into if he were to write "The Piscivore's Dilemma." "Thus, it seems likely that a feeding killer whale that is ingesting cold seawater and food could easily have a stomach temperature of 78☏.Whether something is actually a cure for arthritis, cancer, or impotence is one issue, but I also think we have a strange and somewhat simplistic notion of what constitutes waste in fishing, farming, and many other interactions we have with the world. Their internal temperatures run about 90☏ (32☌), he explained. The only other animal that could take on a small great white-and that has a warmer ambient internal temperature-is the killer whale, Braun said. "Maybe even less at great depth in cold water." That's cooler than the temperature recorded on the tag. "White shark stomach temperatures are thought to be on the order of 65 to 70☏," he explained. White sharks in particular have highly variable diets, he added in an email interview, and are likely opportunistic when it comes to finding food.īut a more likely explanation for the surprising tagging data, said Braun, is that the female great white got caught in the crosshairs of a killer whale. "Cannibalism in sharks is quite common in both juveniles and adults," said Camrin Braun, a doctoral student at the Woods Hole Oceanographic Institution in Massachusetts who studies shark population and behavior. The search for the perpetrator is the subject of a Smithsonian Channel show airing later this month.Įxperts say that speculation that a great white devoured the missing female great white is not outside the realm of possibility. (See "Scientists Track a Great White Shark Across the Atlantic for the First Time.") But "what could kill a three-meter great white?" Riggs asked.
A reddit user posted the video on the popular site this week, and it quickly went viral. The data suggested an attack.įilmmaker David Riggs, who'd been hired to document the tagging project that involved the nine-foot-long female shark, couldn't believe the data at first.Ĭlearly something ate the shark, Riggs said in a YouTube clip uploaded by the Smithsonian Channel a couple of weeks ago. The ambient temperature surrounding the tag spiked from 46☏ to 78☏ (8☌ to 26☌). Its data showed that four months after it was attached, the female great white abruptly dove to a depth of 1,903 feet (580 meters). The tag, initially attached in November 2003 off southwestern Australia, was set to record ambient temperatures and depth.
The shark that disappeared was wearing a research tag, which a beachcomber found 2.5 miles (four kilometers) away from where it had been affixed to the shark. Speculation that a great white shark that went missing off Australia may have been devoured by another great white is making the Internet rounds this week, raising the question of whether it was an instance of shark cannibalism.
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