Big Ideas (the ecologic paradigms that hagfish shifted)
Heincke’s law is one of those ecologic principles that more often acts as a foil for rejecting the null hypothesis than as a consistent pattern in ecology. It’s most basic summary is: The further from shore and the deeper dwelling a fish is, the bigger it grows. Heincke’s law does not appear to be true for hagfish, whose size appear to have no relation to the depth at which they occur. On the other hand, phylogenetic relationships do seem to play some role in regulating body size in hagfish.
Defense and Behavior (how hagfish do the things that they do)
Hagfish are master escape artists, capable of squeezing in and out of tight spaces barely half the width of their body. This great for getting in an out of rotting whale carcasses on the sea floor, creeping into crevices, and avoiding predators. But how do they accomplish this incredible feat? Hagfish have a flaccid sinus under their skin which allows them to control the distribution of venous blood and alter their body width as they wriggle through narrow passages. Freedman and Fudge identified 9 distinct behaviors which take advantage of this adaptation, including anchoring, forming tight loops to push the body through an opening, and bending the hagfish head 90 degrees to force it through a slit. And there are videos!
The Fudge lab has been busy this year, cranking out some of the most noteworthy work on the incredible behavior of hagfish. In addition to examining hagfish motility, Boggett and friends looked into how those flaccid sinuses aid predator avoidance. The team build wee little guillotines loaded with shark teeth to see how hagfish skin protects the animal from vicious bites. In a year when a truckload of hagfish spectacularly crushed a car, the fact that this research was the biggest breakout sensation in hagfish pop culture says everything you need to know about the compelling results of this study. You can read more about this study at The Verge, Futurity, Popular Science, and plenty of other outlets.
2017 was… yeah. Of all the years I’ve lived through, 2017 was definitely one of them. Anyway, some interesting things happened in the world of shark research. Here, in no particular order, are 17 amazing and important things that scientists discovered about sharks and rays over the last year.
1 Sharks can switch between sexual and asexual reproduction. We’ve known that several shark species can reproduce asexually for over a decade now, but this year, Dudgeon and friends showed an individual shark switching between sexual and asexual reproduction for the first time!
I’d like to take a moment rant about a particular pet peeve of mine, which involves the seemingly-dull subject of species common names. As you may have learned in biology class, all identified and described species are assigned a Latin scientific name, which is intended to be a universal identifier of that species regardless of where it’s coming up in conversation. However, scientific names are not typically very familiar to non-scientists, so common names remain the most, well, common way to refer to a species.
One of the most common questions I get during my “ask me anything” sessions on twitter is “which species of sharks are the most endangered?” Whenever I can’t completely answer a question in a single tweet, I like to link to more information from a reliable source.
However, I’ve struggled to easily answer this question with a link, because much of the information out there about this particular question is incomplete, misleading, or just wrong. Several online lists of the most endangered species of sharks* don’t actually include the most endangered species of sharks. Many of these lists could be re-titled as “the conservation status of some species of sharks I’ve heard of and could easily find pictures of” or “some random information I heard out of context about shark conservation.” Since there isn’t an easily accessible source of accurate information about this important shark science and conservation topic, I’ll make one myself. ( I should note here that I am referring only to true sharks, not to other chondrichthyans, even though other chondrichthyans in many cases face similar or worse threats. )
Alastair Harry is a fisheries science practitioner based in Perth, Australia. He assists in implementing ecosystem based fisheries management to support the sustainable use of wild-capture fish resources. He is a generalist and works across multiple areas including stock assessment, bycatch, and threatened species. He also holds an adjunct position at James Cook University and has a specific interest in the conservation and sustainable management of sharks and rays.
In August I published a review paper entitled Evidence for systemic age underestimation in shark and ray ageing studies. In it I suggest that many sharks and rays live considerably longer than is currently recognised. This increased life expectancy isn’t due to medical advancements or a more nutritious diet (or even better fisheries management), but rather the result of ageing error.
Earlier today, the Japan Times reported that a mining tool has successfully extracted zinc and other metals from a hydrothermal vent on the seafloor. There’s not much to go on yet. We don’t know if these were active or dormant vents (though dormant doesn’t mean biologically dead). We don’t know the specific location of the experimental mine site. And we don’t know the footprint of the ore prospect. But we do know that Japan has identified at least 6 potential mining sites within its exclusive economic zone and that plans are moving forward for a commercial mining venture in mid-2020. I’ve only found one report in English and from the look of things, there’s only a press release circulating right now, but I’m certain we’ll be hearing much more about this in the coming weeks.
Japan Agency for Natural resources and Energy
We’re still watching to see what Nautilus Minerals does at Solwara 1 and how manganese nodule mining proposals in the Clarion Clipperton fracture zone are progressing but Japan’s mining efforts present a sea change in how to anticipate future deep-sea mining efforts. Private commercial ventures are dependent on the whims of the global commodities market and subject to national and international regulation. National efforts are driven by the need for resource independence. I was aware of Japan’s efforts, but didn’t realize that they were as close as they are to being ready for production.
For the last 10 years, we’ve been saying that deep-sea mining of hydrothermal vents is imminent. Well, it’s here.
We sampled two sites in Papua New Guinea where these deep-sea mussels aggregate and looked at their genes to determine if there was any population structure across this relatively small spatial scale (~40 km). We found one homogeneous population. We also looked at representatives from other ocean basins and determined that mussel populations within Manus Basin are younger than those in neighboring basins. This is a pattern we’ve observed in several otherstudiesas well.
This is not, by any stretch, a ground-breaking, paradigm-shifting study. But studies like this, baseline, foundation-building studies, are absolutely essential for conservation biology.
A photo used in this study showing a hammerhead shark taken completely out of the water. As with all photos used in this study, the angler’s privacy has been protecting by blurring out his face.
I have a new paper out on the conservation impacts of recreational shark fishing. The paper is called “fishing practices and representations of shark conservation issues among users of a land-based shark angling online forum,” and it is published in the journal Fisheries Research. If you don’t have institutional library access, you can read a copy of the paper here. The goal of this blog post is to provide background information on the study.
Journalists are free to quote or paraphrase information from this blog post. Additionally, I provide some suggested quotes below, and I am available for interviews about this paper (please contact me at WhySharksMatter at gmail).
In the UK, there is a famous and long-running radio show called Desert Island Discs. On this show celebrities are asked to imagine that they are marooned on a desert island, but they have rescued 10 discs (mp3s I suppose these days…) of songs that they have rescued from their sinking ship to keep them company on the desert island.
clipart credit: istock.com
My chum – marine mammal scientist and general ocean hero – Asha De Vos recently asked for a list of key papers in marine conservation that she could pass onto students working on marine conservation issues in Sri Lanka. So I decided to write up my top ten “desert island” marine conservation papers that I think have been influential, and that all marine conservation students should read.