Amazing fish eyes, the real cost of halibut, and protecting local species: Thursday Afternoon Dredging, December 13, 2018

Cuttings (short and sweet):

Spoils (long reads and deep dives):

Please add your own cuttings and spoils in the comments!

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Florida releases draft land-based shark fishing regulations

After months of expert and public consultation, the Florida Fish and Wildlife Conservation Commission has announced the draft text of new regulations that will govern land-based shark fishing. It’s mostly very good news that directly addresses most of our concerns! 

A review of the problem
Land-based anglers in Florida (those who fish from beaches, docks, and piers) catch large numbers of threatened, protected species, handling them in needlessly cruel ways that likely result in mortality or permanent injury. Anglers are aware that what they’re doing causes harm to certain species and violates some existing regulations. Hammerhead sharks in particular are extremely physiologically vulnerable and need to be released much faster than they are currently being released or else they will very likely die. 

(Learn more: see my paper on this subject, my blog post summarizing that paper, an open letter calling for action, an op-ed I wrote about thisa review of the existing rules and how they’re regularly violated, and a years-old blog post describing one problematic incident with land-based shark fishing)

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Dive bombing birds, octopus intelligence, and a red tide update: Thursday Afternoon Dredging, December 6, 2018

Cuttings (short and sweet):

Spoils (long reads and deep dives):

Please add your own cuttings and spoils in the comments!

If you appreciate my shark research and conservation outreach, please consider supporting me on Patreon! Any amount is appreciated, and supporters get exclusive rewards!

Canada announced new marine protected area standards. Here’s how science and conservation professionals reacted.

Recently, the Canadian government released the Final Report of the National Advisory Panel on Marine Protected Area Standards. This report is a set of guidelines and goals for the creation of new marine protected areas in Canada, and comes as Canada is hoping to greatly increase the number and quality of MPAs. I reached out to MPA experts and environmental nonprofits to ask what they think.

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Barndoor skates, once a textbook example of overfishing, have recovered enough to allow fishing

Barndoor skates were once thought to be so overfished that a highly-publicized paper from 1998 noted that they had been “driven to near extinction without anyone noticing.” One of the largest skates, barndoor skates can reach over 5 feet in wingspan, which is large enough that their diet includes small sharks like spiny dogfish; for a skate, that’s about as close as it gets to charismatic megafauna!

Recently, NOAA Fisheries announced that Barndoor skate populations off the Northeastern United States had finally recovered enough that fishing for them could resume. This move comes after a 2009 NOAA Fisheries report showed that the species had begun to recover enough that they could be removed from the species of concern list, though they remained protected at the time. “This is good news,” Mike Ruccio, a Supervisory Fishery Policy Analyst for NOAA Fisheries Greater Atlantic Regional Fisheries Office, told me. “Rebuilding overfished stocks is one of the cornerstones of the US domestic policy on fisheries.”

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Ancient fish farming and popular invasive species: Thursday Afternoon Dredging, October 18th 2018

Cuttings (short and sweet):

Spoils (long reads and deep dives):

Please add your own cuttings and spoils in the comments!

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Banning Arctic fishing and protecting public beach access: Thursday Afternoon Dredging, October 4th, 2018

Cuttings (short and sweet):

Spoils (long reads and deep dives):

Please add your own cuttings and spoils in the comments!

If you appreciate my shark research and conservation outreach, please consider supporting me on Patreon! Any amount is appreciated, and supporters get exclusive rewards!

Dear Shark Man, are the relative sizes of sharks in the “baby shark” dance scientifically accurate?

Welcome to  Dear Shark Man, an advice column inspired by a ridiculous e-mail I received. You can send your questions to me via twitter (@WhySharksMatter) or e-mail (WhySharksMatter at gmail).

Dear Shark Man,
Are Daddy and Grandpa sharks really morphologically bigger than Mommy and Grandma sharks?
Sincerely,
Addicted to “Baby Shark” in Arizona


Dear Addicted,

Thank you for a great question, which allows me to continue teaching science from things that go viral on the internet. First, let’s make sure that everyone’s on the same page about what precisely you are inquiring about.

You’re referencing the viral song “Baby Shark,” which has been made popular recently by the online educational company Pinkfong. (Though, let’s be clear here, the song is much older, I remember singing it at summer camp 25 years ago). The Pinkfong version of the song is an undeniable hit, inspiring remixes, educational parodies, clothing, food,  and even the baby shark challenge.

In case you haven’t seen it yet, you’re welcome:

Anyway, in the song and associated dance, a series of shark age classes are named, and the dancer moves their hands and arms progressively larger to signify an increased gape size (size of open mouth) associated with changes in shark life history. Baby shark is the smallest, mommy and grandma shark are the next largest, and daddy and grandpa shark are the largest. Additionally, both grandma and grandpa shark are shown to have no teeth.

So let’s get back to your question, Addicted. How accurate is the dance associated with “Baby Shark” in terms of portraying the relative dimensions of gape sizes associated with different life history stages of sharks?

Is the gape size of a reproductively mature shark (male or female) larger than that of it’s newborn offspring, which are called either “pups” or “young of year ” or “neonates”? Yes, because the whole shark would be larger. This makes intuitive sense, I hope! Indeed, a mommy or daddy shark would have a dramatically bigger mouth than a baby shark. The size disparity becomes a little blurrier when you’re talking about not-quite-reproductively-mature juveniles and have-just-become-reproductively-mature young adults, but the difference between baby and mommy or daddy sharks is noticeable.

Are reproductively mature adults old enough to have reproductively mature offspring going to be approximately the same size as their reproductively mature offspring? In other words, are grandma sharks the same size as mommy sharks, and are grandpa sharks the same size as daddy sharks? No. Sharks have what’s called “indeterminate growth,” which means that they continue growing throughout their lives. Therefore, grandma sharks would be larger than mommy sharks, and grandpa sharks would be larger than daddy sharks. This difference in size (and associated gape size) would not be as drastic as the difference in size between that of mommy/daddy sharks vs. baby sharks, however, because growth rate slows down as sharks age.

Next, are reproductively mature adult male sharks larger than reproductively mature adult female sharks? In other words, are daddy sharks bigger than mommy sharks, and are grandpa sharks bigger than grandma sharks? Typically not! In many (I’m always hesitant to say “all” because sharks are weird, but I don’t know of a counterexample) species of sharks, the females are larger than the males. The reasons for this are complex, but if you think of it in terms of how much energy and effort and space it takes to make sperm vs. eggs (or how much energy and effort and space it takes to have pups grow inside you), it makes some intuitive sense. In some other fish species, the smaller younger individuals are all males, and they *turn into* females when they age and grow, a phenomenon known as protandrous sequential hermaphroditism. (This happens with clownfish, which would have made Finding Nemo a very different movie if they paid a little more attention to scientific accuracy).

Finally, would older grandma and grandpa sharks have lost all their teeth as they aged? In reality, many shark species can continually regrow new teeth throughout their lifetime (sometimes going through thousands of teeth per individual shark). This is good, because when you’re a wild predator and you don’t have any teeth, you can’t eat and you, um, die.

So in summary, Addicted, “Baby Shark” is catchy as hell, but is not a new song, and the associated dance is not scientifically accurate. Put another way, the song is not quite right, doo doo doo doo doo, not quite right, doo doo doo doo doo, not quite right doo doo doo doo doo, not quite right.


If you appreciate my shark research and conservation outreach, please consider supporting me on Patreon! Any amount is appreciated, and supporters get exclusive rewards!

What to do after the first fatal shark bite in Massachusetts since 1936: 3 experts respond

Two weeks ago, tragedy struck in New England as a boogie boarder was killed by a great white shark. Though shark bites* in general and fatal shark bites* specifically are incredibly rare (Mr. Medici was the first person killed by a great white shark in Massachusetts waters in 82 years), emotions are running high. Some Cape Cod residents are explicitly calling for a cull (targeted killing) of great white sharks.

Such a cull would be devastating for a recovering but still protected shark species, has been shown not to effectively reduce shark bites, and is opposed by shark experts around the world, but what, if anything, should local governments do instead? I’ve written in the past about alternatives to lethal shark control here and here, but not every solution is applicable for every location; local oceanographic conditions vary, as well as local laws and cultural norms. I reached out to three experts to ask what, if anything, they think should be done here. Here’s what they had to say:

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Angry Canadian Crabs and Extinct Australian Sea Stars: Thursday Afternoon Dredging, September 27(8)th 2018

 

It’s a special Friday morning edition of Thursday Afternoon Dredging because I was traveling!

Cuttings (short and sweet):

Spoils (long reads and deep dives):

Rules of the road (news about regulations governing the ocean) 

SCALLOPPPPPPPPPPPP WARRRRRRRRRRRRRRRRRRR (An update on the brewing BREXIT-related war over scallop fishing rights between the UK and the EU): 

Please add your own cuttings and spoils in the comments!

If you appreciate my shark research and conservation outreach, please consider supporting me on Patreon! Any amount is appreciated, and supporters get exclusive rewards!