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September 20, 2012
01:41 AM
243 views

Heartbreaking and Heartwarming Tales of Social Sharks

by Chuck in Ya Like Dags?

One of the cooler trends in marine science has been the revelation that advanced social and learning behavior are pretty widespread among marine animals, and not just the domain of marine mammals. Stereotypically, whales and dolphins are considered the big-brained residents of the ocean, able to outsmart everything else with their adorable group behavior. The truth is more complex and therefore a lot more interesting: several marine taxa from bony fish to cephalopods have proven quite smart, and some marine mammals are not so smart (the North Atlantic right whale was considered the “right” whale to hunt, and continues to be critically endangered, because they are spectacularly dumb). Fortunately for my own particular bias, sharks are following this trend. A couple newer papers show that not only are sharks highly social, but their social behavior can be just as heartbreaking and heartwarming as that of any charismatic megafauna.... Read more »

Guttridge, T.L., van Dijk, S., Stamhuis, E.J., Krause, J., Gruber, S.H., & Brown, C. (2012) Social learning in juvenile lemon sharks, Negaprion brevirostris. Animal Cognition. DOI: 10.1007/s10071-012-0550-6

McPherson, D.L., Blaiyock, K.V., & Masse, W.V. (2012) Lethal Ramming of Sharks by Large Jacks (Carangidae) in the Palau Islands, Micronesia. Pacific Science, 327-333. info:/10.2984/66.3.6

June 13, 2012
12:08 AM
383 views

Declining Predators eat Mediterranean Jellies

by Chuck in Ya Like Dags?

ResearchBlogging.orgIt wasn’t my intention to keep picking on the Mediterranean, but this paper was just too damn interesting. In the Mediterranean, like many other marine environments worldwide, numbers of jellyfish and ctenophores (those really colorful comb jellies, actually not related to jellyfish) have recently exploded. According to a recent PLoS One paper by researchers from the University of Barcelona (Cardona et al. 2012), a possible explanation may be that their predators are overfished. This isn’t too shocking a finding (especially in the consistently overfished Mediterranean), but what is interesting is just who some of those predators are. Also, this paper represents exactly what I like to see in a stable isotope paper.... Read more »

Cardona, L., Álvarez de Quevedo, I., Borrell, A., & Aguilar, A. (2012) Massive Consumption of Gelatinous Plankton by Mediterranean Apex Predators. PLoS ONE, 7(3). DOI: 10.1371/journal.pone.0031329

June 6, 2012
10:36 PM
566 views

How Italy Ate Up All Its Sharks

by Chuck in Ya Like Dags?

As dramatically imperfect as U.S. fisheries management can be, I still stand by my stance that we have the best-managed fisheries in the world. Fishermen gripe about it being too restrictive and quick to change, conservationists complain about it being too lenient and slow to adapt, and both have a point. That said, we could do much worse than the job NMFS is doing. This is especially true for shark and ray fisheries, where the old practice of lumping all but a few species into one of two “coastal shark complexes” is giving way to species-specific management. This is perhaps most dramatic for the scalloped hammerhead, which is finally getting its own stock assessments and may be headed for Endangered Species listing. We’ve come a long way since crashing the Atlantic cod population. But not every country does as good a job as us…... Read more »

Dell'Apa, A., Kimmel, D., & Clo, S. (2012) Trends of fish and elasmobranch landings in Italy: associated management implications. ICES Journal of Marine Science. DOI: 10.1093/icesjms/fss067

March 28, 2012
09:10 PM
746 views

Great White Sharks Attack Whales. Seriously.

by Chuck in Ya Like Dags?

During a literature search for some dissertation-related stuff I stumbled upon quite possibly the most awesome paper ever for a shark fan. It’s well-known that sharks, especially large, migratory species, supplement their diet of fish and sea mammals by scavenging on whale carcasses. It’s been theorized that whale carcasses are a very important food source for migrating sharks, but it seems like a relatively unreliable food scource: most large sharks don’t hunt cooperatively and even a 20-foot great white is highly unlikely to take down a 40-foot whale, so the sharks have to wait for something else to kill the whale. Or not. Apparently some sharks have taken matters into their own jaws and rather than waiting for whale carcasses, they create them.... Read more »

Taylor, J., Mandelman, J., McLellan, W., Moore, M., Skomal, G., Rotstein, D., & Kraus, S. (2012) Shark predation on North Atlantic right whales (Eubalaena glacialis) in the southeastern United States calving ground. Marine Mammal Science. DOI: 10.1111/j.1748-7692.2011.00542.x

March 25, 2012
06:25 PM
371 views

The Most Badass Fish in the Sea

by Chuck in Ya Like Dags?

You might think that the title of this post refers to the spiny dogfish (Squalus acanthias), the main species of interest for this blog. You’d be wrong. You’d also be wrong to guess the great white, as badass a shark as that is. This post is dedicated to a shark that, despite its relatively average size (by large shark standards), makes its living eating prey that are themselves infamous for being voracious predators. This post is dedicated to the velociraptor of the sea, the shortfin mako (Isurus oxyrinchus).... Read more »

Stillwell, C. E., & Kohler, N. E. (1982) Food, Feeding Habits, and Estimates of Daily Ration of the Shortfn Mako (Isurus oxyrinchus) in the Northwest Atlantic. Canadian Journal of Fisheries and Aquatic Science, 407-414. info:/

March 19, 2012
06:56 PM
738 views

Dogfish and Seals Taking a Bite out of Fisheries?

by Chuck in Ya Like Dags?

ResearchBlogging.orgIt should be no secret to readers of this blog or anyone familiar with fisheries at all that spiny dogfish have a pretty rotten reputation among commercial fishermen. Quickly approaching the notoriety of dogfish are those damn dirty sea mammals, the harbor seals. Both animals have enjoyed recent increases in population: dogfish from a period of proactive fishery management, and seals from riding along on the Marine Mammal Protection Act. Arguments against protections for both of these species usually hinge on the alleged economic damage they do to fisheries by stealing the catch, destroying gear, and consuming commercially-important species. However, until recently there hasn’t been much concrete information on just how damaging these “pests” can be. A new paper by researchers working in the Cape Cod gillnet fishery attempts to answer that question, at least for New England groundfish.... Read more »

RAFFERTY, A., BRAZER, E., & REINA, R. (2012) Depredation by harbor seal and spiny dogfish in a Georges Bank gillnet fishery. Fisheries Management and Ecology. DOI: 10.1111/j.1365-2400.2011.00837.x

January 27, 2012
01:27 AM
838 views

The Social Shark Network

by Chuck in Ya Like Dags?

Recently Jason Goldman at the great blog The Thoughtful Animal (if you have any interest in animal behavior at all, you should be following it) put up a post titled “Sharks With Friends.” In that post, he summarizes a recent paper showing that blacktip sharks (Carcharhinus melanopterus) from schools with the same individuals. Social behavior in sharks is a big interest of mine because my Masters thesis study animal, the mighty spiny dogfish (Squalus acanthias) is among the most social sharks out there, forming huge schools as they migrate along the coast. However, this recent paper is not the first to study social behavior in sharks, though it does have a really cool result and methodology that I’ll got into later. Though dolphins and octopuses get a lot of credit for being the smartest creatures in the sea, sharks may be just as complex in their social behavior, meaning they might be capable of hatching world domination schemes just as diabolical as those of the cetaceans and cephalopods. Sharks also have the advantage of being able to eat dolphins and octopuses. I for one welcome our finned overlords.... Read more »

Guttridge, T., Gruber, S., Gledhill, K., Croft, D., Sims, D., & Krause, J. (2009) Social preferences of juvenile lemon sharks, Negaprion brevirostris. Animal Behaviour, 78(2), 543-548. DOI: 10.1016/j.anbehav.2009.06.009

Jacoby, D., Busawon, D., & Sims, D. (2010) Sex and social networking: the influence of male presence on social structure of female shark groups. Behavioral Ecology, 21(4), 808-818. DOI: 10.1093/beheco/arq061

Mourier, J., Vercelloni, J., & Planes, S. (2011) Evidence of social communities in a spatially structured network of a free-ranging shark species. Animal Behaviour. DOI: 10.1016/j.anbehav.2011.11.008

January 9, 2012
12:41 AM
882 views

Ageing Spiny Dogfish: Are We Doing it Wrong?

by Chuck in Ya Like Dags?

Welcome to the first post in 2012. It’s probably good to start the new year off with a doozy, and in keeping with the theme of this blog, it involves that scrappy little shark everyone loves to hate. Spiny dogfish are possibly the most well-studied shark species, by virtue of being relatively common and easy to handle, but there is always room to learn something new or revisit something we thought we knew (especially with regards to dogfish ecology). One of the best-known features of spiny dogfish is its longevity and slow growth, but a new paper by researchers from the University of New Hampshire and the University of New England shows that the specifics of spiny dogfish age and growth are not written in stone.... Read more »

Bubley, W., Kneebone, J., Sulikowski, J., & Tsang, P. (2011) Reassessment of spiny dogfish Squalus acanthias age and growth using vertebrae and dorsal-fin spines. Journal of Fish Biology. DOI: 10.1111/j.1095-8649.2011.03171.x

Nammack, M. F., Musick, J. A., & Colvocoresses, J. A. (1985) Life History of Spiny Dogfish off the Northeastern United States. Transactions of the American Fisheries Society, 367-376. info:/

December 17, 2011
10:32 PM
1,053 views

Who's Eating Atlantic Salmon?

by Chuck in Ya Like Dags?

Atlantic salmon (Salmo salar) just can’t catch a break. Like their Pacific counterparts, Atlantic salmon are anadromous, meaning they live in the ocean as adults, but swim upriver to spawn. Despite having the evolutionary advantage of being able to spawn more than once in their lives, Atlantic salmon had the bad luck of requiring rivers in areas with some of the most dense human populations on the planet. Overfishing took its toll, but dam construction and habitat degradation, all resulting from human settling along the rivers, have combined to make wild Atlantic salmon almost functionally extinct. The species largely exists today in salmon farms and landlocked lakes where it has been stocked.... Read more »

FRIEDLAND, K., MANNING, J., LINK, J., GILBERT, J., GILBERT, A., & O’CONNELL, A. (2011) Variation in wind and piscivorous predator fields affecting the survival of Atlantic salmon, Salmo salar, in the Gulf of Maine. Fisheries Management and Ecology. DOI: 10.1111/j.1365-2400.2011.00814.x

October 13, 2011
12:06 AM
723 views

Trawling is Not Plowing

by Chuck in Ya Like Dags?

This probably should have gone under the annual Southern Fried Science Week of Ocean Pseudoscience, but last week kept me busy enough to effectively prevent me from doing any writing here. For some reason, I’ve been hearing from multiple fishermen, people who have worked with my labmates and are generally pretty smart people, that trawling is “good for the seafloor.” This was covered back in December over at Deep Sea News, regarding a study on mud bottom habitats that aimed to see whether this was the case. As marine biologists, conservationists, or fisheries scientists, we likely assume that trawling isn’t so great for the environment, since by its nature it pretty much obliterates everything in its path. However, at least a few rather intelligent commercial fishermen (and according one of them, at least one college professor) have really latched onto the idea that trawling actually improves the environment by stirring up relatively homogenous environments and creating structure where there wasn’t any. If we resist the instinct to yell “holy crap that’s wrong,” it almost makes a little sense: like plowing a field, it stirs up nutrients, which in agricultural fields allows for increased growth. So plowing the seafloor is like plowing a cornfield, which is good for the corn, so plowing must work like that underwater, right?... Read more »

Freese, L., Auster, P., Heifetz, J., & Wing, B. (1999) Effects of trawling on seafloor habitat and associated invertebrate taxa in the Gulf of Alaska. Marine Ecology Progress Series, 119-126. DOI: 10.3354/meps182119

Hinz, H., Prieto, V., & Kaiser, M. (2009) Trawl disturbance on benthic communities: chronic effects and experimental predictions. Ecological Applications, 19(3), 761-773. DOI: 10.1890/08-0351.1

Hiddink, J.G., Johnson, A.F., Kingham, R., & Hinz, H. (2011) Could our fisheries be more productive? Indirect negative effects of bottom trawl fisheries on fish condition. Journal of Applied Ecology. info:/10.1111/j.1365-2664.2011.02036.x 2011

Loher, T., & Armstrong, D.A. (2000) Effects of habitat complexity and relative larval supply on the establishment of early benthic phase red king crab (Paralithodes camtschaticus Tilesius, 1815) populations in Auke Bay, Alaska. Journal of Experimental Marine Biology and Ecology, 245(1), 83-109. DOI: 10.1016/S0022-0981(99)00157-4

Prena, J., Schwinghamer, P., Rowell, T.W., Gordon, Jr., D.C., Gilkinson, K.D., Vass, W.P., & McKeown, D. (1999) Experimental otter trawling on a sandy bottom ecosystem of the Grand Banks of Newfoundland:analysis of trawl bycatch and effects on epifauna. Marine Ecology Progress Series, 107-124. DOI: 10.3354/meps181107

September 20, 2011
10:16 PM
1,154 views

Spiny Dogfish Munch Viruses?

by Chuck in Ya Like Dags?

ResearchBlogging.orgI’ve been on hiatus for a little bit as I adjust to the workload inherent in starting a PhD program (while putting the finishing touches on a thesis, but that’s neither here nor there…), so that’s my excuse for not posting on this story until pretty much everyone else had. In case you hadn’t heard, the compound squalamine, found in sharks (and named for the spiny dogfish) and sea lampreys, is apparently capable of inhibiting and even halting the spread of viruses in human beings. Unfortunately, sharks have a long and unfortunate history of being associated with supposed “miracle cures,” often to the detriment of the sharks. I managed to get a look at the actual paper (tip o’ the hat to Lyndell, even if she never blogs anymore) to see how this new breakthrough works out for both people and sharks.... Read more »

M. Zasloff, A.P. Adams, B. Beckerman,, A. Campbell,, Z. Han,, E. Luijten,, I. Meza,, J. Julander,, A. Mishra,, W. Qu,.... (2011) Squalamine as a broad-spectrum systemic antiviral agent with therapeutic potential. PNAS. DOI: 10.1073.1108558108

August 30, 2011
06:15 PM
1,424 views

New Dogfish Species Found in Taiwanese Fish Market

by Chuck in Ya Like Dags?

The Order Squaliformes, home to the dogfish sharks, is one of the most diverse groups of sharks currently swimming the oceans, second only to the Carcharhiniformes in sheer number of species. Within that order is the Family Squalidae, made up of the very familiar spiny dogfish Squalus acanthias (the star of this blog) and a bunch of species that look pretty similar to it. New species tend to pop up in this group, since most of these sharks look pretty similar and the majority of them live in the deep sea. Recently one species was “rediscovered” in plain sight; the North Pacific spiny dogfish Squalus suckleyi had been considered a population of S. acanthias but has been restored to species status by genetic analysis. Now, researchers have found an entirely new Squalus species in the Tashi Fish Market in Taiwan. Say hello to Squalus formosus.... Read more »

White, W.T., & Iglesias, S.P. (2011) Squalus formosus, a new species of spurdog shark (Squaliformes: Squalidae), from the western North Pacific Ocean. Journal of Fish Biology. info:/doi:10.1111/j.1095-8649.2011.03068.x

August 22, 2011
08:45 PM
1,491 views

Sharks of the Jersey Shore

by Chuck in Ya Like Dags?

Just got back from a little pre-school-year vacation visiting the Hot Girlfriend up in New Jersey, which has seen its share of shark sightings this summer. New Jersey has a long history with sharks, what with the first high-profile string of shark attacks in U.S. waters occurring there (which would go on to inspire Jaws and, in turn, create the demand for most modern shark research). Unfortunately for those who actually live in New Jersey, the state and the shore region in particular are now better known for fake tans, gelled hair, and Affliction t-shirts. However, there is another group of visitors to the Jersey Shore that would probably make The Situation and company nervous at the beach (not that, in the episodes I’ve actually seen, they’ve ever set foot on the beach or in the water, but I digress). These are the sharks of the Jersey Shore.... Read more »

Hammerschlag, N., Gallagher, A.J., Lazarre, D.M., & Slonim, C. (2011) Range extension of the endangered great hammerhead shark Sphyrna mokarran in the Northwest Atlantic: preliminary data and significance for conservation. Endangered Species Research, 111-116. info:/10.3354/esr00332

Merson, R.R., & Pratt, H.L. (2001) Distribution, movements and growth of young sandbar sharks, Carcharhinus plumbeus, in the nursery grounds of Delaware Bay. Environmental Biology of Fishes, 13-24. info:/

July 31, 2011
12:12 PM
1,432 views

101 Uses for Shark Puke Part 2: How Much Do Sharks Eat?

by Chuck in Ya Like Dags?

The last time I wrote about the usefulness of shark puke, I discussed a few of the less obvious uses of diet studies on sharks. As apex predators, sharks can sample a wide variety of potential prey species, and diet studies can provide just as much information on those species as the sharks themselves. That said, the main function and justification for sifting through shark vomit is to figure out what kind of predatory impact the sharks have, which lets us know how these predators fit into the ecosystem and adjust fisheries models accordingly, put protections in if the most important prey are declining, or see if the food web needs any “adjusting” (always a popular topic at fishery advisory council meetings). In order to figure this out, scientists need to figure out just how much food a shark needs, and there are some nifty ways of doing this.... Read more »

Bush, A., & Holland, K. (2002) Food limitation in a nursery area: estimates of daily ration in juvenile scalloped hammerheads, Sphyrna lewini (Griffith and Smith, 1834) in Kane’ohe Bay,O’ahu, Hawai’i. Journal of Experimental Marine Biology and Ecology, 157-178. info:/

Olson, R., & Mullen, A. (1986) Recent developments for making gastric evacuation and daily ration determinations. Environmental Biology of Fishes, 16(1-3), 183-191. DOI: 10.1007/BF00005170

June 20, 2011
10:41 PM
1,439 views

101 Uses of Shark Puke

by Chuck in Ya Like Dags?

Earlier today WhySharksMatter and I had a little light-hearted smack talk about new-school (stable isotopes) vs. old-school (gastric lavage or straight-up dissection) methods of measuring the diet of sharks. These are the things you could be privy to if you were following me on that newfangled Twitter thing (at “press time” I only have 113 followers so there’s still room to get in on the ground floor). This coincided with/provided procrastination during one of my occasional literature searches to make sure I’m not missing some brilliant paper on shark feeding habits that I should be citing (grad school life is thrilling), and got me to thinking about what else we can learn from shark puke.... Read more »

Link, J., & Ford, M. (2006) Widespread and persistent increase of Ctenophora in the continental shelf ecosystem off NE USA. Marine Ecology Progress Series, 153-159. DOI: 10.3354/meps320153

Markaida, U., & Sosa-Nishizaki, O. (2010) Food and feeding habits of the blue shark Prionace glauca caught off Ensenada, Baja California, Mexico, with a review on its feeding. Journal of the Marine Biological Association of the United Kingdom, 90(05), 977-994. DOI: 10.1017/S0025315409991597

May 23, 2011
09:43 PM
1,475 views

Reproduction: Secret Weapon of the Dogfish?

by Chuck in Ya Like Dags?

Spiny dogfish are one of the rare success stories in the management of shark fisheries, with the U.S. Atlantic population representing one of the few shark stocks ever to fully recover from overfishing. At first glance this doesn’t seem to make any sense: spiny dogfish are one of the longest-lived and slowest-growing of the sharks that regularly interact with human beings, and with a 2-year pregnancy it doesn’t seem as though they could replace their numbers in anything less than the decades that have gone by without successful recovery from several other heavily-fished sharks. So how have spiny dogfish been able to succeed in recovering from overfishing where so many other sharks struggle? The answer may very well be in adaptations related to that seemingly long reproductive cycle of theirs.... Read more »

Carrier, J.C., Pratt, H.L., & Castro, J.J. (2004) Reproductive biology of elasmobranchs. Biology of Sharks and Their Relatives, 269-286. info:/

Hanchet, S. (1988) Reproductive biology of Squalus acanthias from the east coast, South Island, New Zealand. New Zealand Journal of Marine and Freshwater Research, 22(4), 537-549. DOI: 10.1080/00288330.1988.9516324

April 21, 2011
09:44 PM
1,494 views

Protected Sharks Still Eat Fish

by Chuck in Ya Like Dags?

mid the constant talk of lowered biodiversity, invasive species, habitat destruction, global climate change, and any other examples of how thoroughly we as a species have wrecked the planet, it’s always good to hear an actual success story in conservation. Obviously it’s never good news for a species to get to a point where it needs to be protected as an endangered species, but sometimes those protections come into play in time to not only preserve the species, but enable it to rebuild and eventually flourish. However, what can be easily forgotten in the joy of saving a species is that that species will continue to do the things it was doing when it was rare, but now with a restored population.... Read more »

Lucifora, L., García, V., & Escalante, A. (2009) How can the feeding habits of the sand tiger shark influence the success of conservation programs?. Animal Conservation, 12(4), 291-301. DOI: 10.1111/j.1469-1795.2009.00247.x

April 13, 2011
11:12 PM
1,573 views

How to Not Catch Dogfish

by Chuck in Ya Like Dags?

Even the biggest fan of spiny dogfish can’t deny that these little sharks sure are great at choking up entire nets. This is especially problematic for commercial fishermen who are trying to catch anything other than dogfish, and particularly for … Continue reading →... Read more »

David M. Chosid, Michael Pol, Mark Szymanski, Frank Mirarchi, & Andrew Mirarchi. (2011) Development and observations of a spiny dogfish Squalus acanthias reduction device in a raised footrope silver hake Merluccius bilinearis trawl. Fisheries Resarch. info:/10.1016/j.fishres.2011.03.007

March 21, 2011
09:59 PM
1,676 views

Unintentional Shark Tagging

by Chuck in Ya Like Dags?

This might possibly be the most awesome paper about tagging fish ever. One of the handiest advances in telemetry, especially of large, highly-migratory oceanic species, has been the advent of SPOT tags. These tags do it all: movement, depth, temperature, … Continue reading →... Read more »

David W. Kerstetter, Jeffery J. Polovina, & John E. Graves. (2004) Evidence of shark predation and scavenging on fishes equipped with pop-up satellite archival tags. Fishery Bulletin, 750-756. info:/

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