John Hlavin

Charting the course for management: a global analysis of effects of vessels on marine megafauna - npj Ocean Sustainability npj Ocean Sustainability - Charting the course for management: a global analysis of effects of vessels on marine megafauna

⚠️NO WAKE SCROLL ZONE⚠️
🚤Proceed reading at idle speed⛴️

New meta-analysis from @juliasaltzman.bsky.social untangles the effects of vessel disturbance on marine megafauna, published open access in npj Ocean Sustainability!

doi.org/10.1038/s441...

ICYMI (it being my most recent research publication) ⬇️

Another new publication! Congrats @juliasaltzman.bsky.social

Behavioral Evidence of Predator–Predator Commensalism: Cobia Track and Feed on Prey Disturbed by Southern Stingrays We documented a novel predator–predator commensal foraging interaction between cobia (Rachycentron canadum) and a southern stingray (Hypanus americanus) in a shallow coastal habitat of Biscayne Bay, ...

🚨NEW 🐟 PAPER 🚨
On this episode of unusual animal friends…
@juliasaltzman.bsky.social was in the right place at the right time to record and generate an ethogram of a stingray-cobia pair, an interaction fishers have relied on to find and sight-fish for cobia!

onlinelibrary.wiley.com/doi/10.1111/...

Is the seagrass greener on the other side? Faster growth in Biscayne Bay, Florida’s nurse sharks (Ginglymostoma cirratum) compared to neighboring conspecifics of Bimini, The Bahamas - Environmental Bi... Effective management of vulnerable species requires a precise understanding of life history. In 2024, Fadool et al. published the first von Bertalanffy growth model for the nurse shark (Ginglymostoma ...

Check out our new publication on the growth rates and habitat use of nurse sharks in Biscayne Bay, FL compared to nearby Bimini, Bahamas which came out today (open access) in Environmental Biology of Fishes! link.springer.com/article/10.1...

Hypothesis: better Cuban food

Is the seagrass greener on the other side? Faster growth in Biscayne Bay, Florida’s nurse sharks (Ginglymostoma cirratum) compared to neighboring conspecifics of Bimini, The Bahamas - Environmental Bi... Effective management of vulnerable species requires a precise understanding of life history. In 2024, Fadool et al. published the first von Bertalanffy growth model for the nurse shark (Ginglymostoma ...

Maybe a link that didn’t open to the reference list would be good 🤦🏻‍♂️ It’s still early(ish)

link.springer.com/article/10.1...

PS Get yourself a PI that conveniently already has the data to answer random questions. Shoutout @drcatmac.bsky.social

Is the seagrass greener on the other side? Faster growth in Biscayne Bay, Florida’s nurse sharks (Ginglymostoma cirratum) compared to neighboring conspecifics of Bimini, The Bahamas - Environmental Bi... Effective management of vulnerable species requires a precise understanding of life history. In 2024, Fadool et al. published the first von Bertalanffy growth model for the nurse shark (Ginglymostoma ...

🚨New 🦈 paper🚨

Who would have thought that only 80 km of separation across the Straits of Florida would be enough to create significant differences in age and growth of Atlantic nurse sharks? Well… now us!

Curious? Open access article linked below

link.springer.com/article/10.1...

New Manta paper!!! Congrats and great work, Emily! 🥳

Open access and linked below

doi.org/10.1007/s002...

Oh my gosh that’s really cool! Thank you for inspiring it!

Doing really well! Completely lucked out stumbling into the world of shark ecology under some really great mentors, including David! Got excited seeing your name pop up on my feed, I’ll always remember your class, so unique compared to the rest of the bio courses I took! How are you?

Woah, crazy collision of past and present worlds!! @caraocobock.bsky.social taught me an absolutely awesome course on biological anthropology at ND! Fall 2019 if I’m remembering correctly

Thanks David! The trap fisheries will not be thrilled if true 😅

We swabbed their bums for trace amounts of fecal DNA, and when tiger sharks voluntarily regurgitated some material during working ups (as they are known to occasionally do) we opportunistically collected that vomit too! No pumped stomachs here 🐅🦈

#AES25 #JMIH25

Finally, @marinebiojohn.bsky.social John Hlavin, Reconstructing diets of Tiger Sharks in South FL

Thanks Carlyanne!! 🐅🦈

John’s title slide showing a juvenile tiger sharks

@marinebiojohn.bsky.social at #JMIH25 #AES25

A multi-method approach can help determine the diet of tiger sharks, different methods have pros and cons. Includes data from 67 Tiger sharks- I think I helped get data on 6 of these!

Whoa- @marinebiojohn.bsky.social found *cow* and *pig* among tiger shark diet.

(He thinks they were bait in lobster and crab traps)

Thanks for sharing!!

Energetic benefits of prey choice for a shark-eating shark - Oecologia Optimal foraging theory has been used to understand the foraging choices of animals but is rarely applied to large predatory fishes due to difficulties measuring their behavior in the wild. Great hamm...

This was a HUGE effort with LOTS of field time and LOTS of analysis – huge thank you to all my coauthors and the many folks who contributed in the field. Very proud of this one. (4/4)

@dr-yannis.bsky.social 🦑🧪🌊🐟

See the paper: link.springer.com/article/10.1...

Maybe this is an appropriate step for prestigious high impact journals like Nature, which should be the epitome of rigor and which young scientists may not be targeting right away anyway, but it might further dissuade that “deep three pointer” attempt. Anyway, thanks for prompting this!

I look at peer review like refining precious metals. Initial submissions should be allowed to be lumps of (well-reasoned and ethical) ore. When researchers are young or venturing into a new discipline/method, initial submissions open to scrutiny might discourage ventures beyond comfort zones.

So with that in mind, I think there’s already an inner voice of imposter syndrome whispering doubts of whether my published work will impress the veterans in my field enough. So for those vets to also be able to scrutinize a paper in its infancy is intimidating and might poke that insecurity.

Yes, actually! Most if not all of it does resonate with me! Thank you for the thoughtful response. I think my initial hesitation comes from a place of being a very early career scientist with only a few experiences of having my own work reviewed / being a reviewer.

All for double blind/disclosing reviewer identities, but total transparency of initial submissions, revisions, and comments/responses feels a bit like making artists hang their scrapbooks up next to their masterpiece… interested in your thoughts!

Further coverage, this time by @forbes.com columnist & #shark researcher @melissacmarquez.bsky.social, about the new paper on #hammerheadsharks using #BiscaneBay, #Florida as a #nursery

Column quotes @drcatmac.bsky.social

www.forbes.com/sites/meliss...

A rare shark is seeking refuge in Miami's Biscayne Bay. Here's why scientists just spent 8 years tracking it | Discover Wildlife A new study reveals that Biscayne Bay is a vital year-round nursery and seasonal refuge for one of the world's most endangered shark species.

A new post from DiscoverWildlife covers the 2025 research from @marinebiojohn.bsky.social and @drcatmac.bsky.social showing tat #BiscayneBay is a nursery area for #hammerhead #sharks

www.discoverwildlife.com/animal-facts...

This is wild:

Recently, I spotted a critically endangered great hammerhead… in the middle of urban Miami. It wasn’t a fluke.

@marinebiojohn.bsky.social & @drcatmac.bsky.social published a study today showing this bay — full of yachts, crab traps, & fishing boats — is a vital nursery habitat. 🌎🦑🧪