A new breeding program aims to revive the gray nurse shark
Ahoy once again, me faithful readers! ‘Tis been too long since our last voyage, and some interesting goings-on have passed me harbor in the meantime. First, I share some grave news for me fellow pirates — that happens to be good news for me fellow greens: Greenpeace has been a’pirate huntin’ off West Africa! I’d suggest they walk the plank for that, had I not seen this bit here: “Pirate fishing is a global threat to the oceans and those who depend on them.” Well, I do reckon I’m in that second camp, and thus I raise my rum noggin to their efforts. And while I’ve got that rum noggin raised, let me also make mention of these poor buckos, who are trying to count every last fish in the sea for the sake of science. Godspeed with that project, I say. Godspeed.
And speaking of counting fish, I share with ye this story about dwindling gray nurse shark (pictured above, copyright Richard Ling) numbers in Australia and what scientists are doing about it: They’re using artificial wombs.
Gray nurse sharks (called sand tigers off the U.S. East Coast) are “some of the meanest-looking, most endangered and, as it turns out, most mild-mannered sharks in the world.” In fact, they’re known as the “Labradors of the sea.” But a Jaws mentality has resulted in the species being “hooked, netted, and spear-hunted” for decades, to the point that the population is struggling to survive. Which is where the artificial wombs come in. The WP article describes it better than I could (extra !! are mine, of course):
As the top predator in its environment, the gray nurse shark is crucial to maintaining ecological stability in the regions in which it lives. But a quirk in the species’ reproductive biology makes it difficult for the creatures to rebuild their numbers.
Females have two separate uteruses(!), with each womb serving as home to as many as 20 fertilized eggs. It’s a picture of great fecundity, and a litter of 40 would be a blessing. But life inside a gray nurse womb is not that simple.
Soon after developing their primordial jaws and teeth, and while still about four inches long, the gill-slitted fetuses attack each other in what shark biologist Nick Otway calls a “battle royal” of sibling cannibalism(!!). The mayhem ends with just two surviving offspring — one in each uterus.
Otway, who works with the New South Wales Department of Primary Industries, which oversees that state’s fisheries programs, foresees a braver and newer way to make gray nurse sharks: artificial wombs, each big enough to hold a three-foot-long baby, which is how big gray nurses are at birth.
The idea is to use endoscopic surgical tools to remove dozens of embryos from pregnant females — including some inseminated with sperm from distant males to boost genetic diversity — then give each embryo its own fluid-filled, climate-controlled tank to grow in.
Blimey! Could shark biology be more fascinating?
Unfortunately, there are risks associated with the proposed faux-womb idea, and some say protecting habitat (which is threatened by Australia’s politically powerful fishing industry) is more important. Meanwhile Otway is continuing work on a preliminary prototype.
And I, dear hearties, am catching up on my shark-bio reading on the poop deck. ‘Til next time: Fair winds!
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