Halloween Science: Fear Makes the Ocean Go Around

Halloween, in a lot of ways, is a celebration of fear.  We dress like ghosts, goblins, and movie serial killers to give ourselves a sense of control over the things we’re afraid of.  It’s also a good time of year to indulge in horror movies, where we can watch ghosts, goblins, and serial killers terrorize other people from the apparent safety of our own homes.

From an ecological standpoint, we have it pretty good.  We’ve more or less tamed most environments on land and only make short forays into the oceans under conditions where we still have quite a few advantages.  Most of the time we have more in common with Jason than his hapless victims.  Imagine being a member of a school of menhaden or a seal that has to make daily trips through Shark Alley.  It would be like spending your whole life as a camp counselor at Crystal Lake, constantly looking over your shoulder and getting picked off the second you let your guard down.  If mortal terror was a regular part of your life, you’d better believe it would affect your daily habits.  And if every member of your species lived with that same fear, there would be places no one in their right mind would go and choices between death by starvation and possible death by being eaten.  After all, fish are always eating other fish.  Let’s take a journey through the low end of the food web and see what horror can teach us about marine ecology.

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Climate Change is Moving Fish Around

Back in the day, I worked as an intern at Rhode Island Marine Fisheries, where my job was basically to provide general field work help with whatever survey needed an extra pair of hands (yes, it was an awesome job).  One of these was a beach seining survey looking at juvenile fishes using Rhode Island’s coastal salt ponds as nursery habitat.  Among the usual silversides, mummichogs, and juvenile flounder, two of the ponds were also home to entire schools of something that I was only familiar with due to having relatives in Virginia: spot.  These little Scianids, a member of the same family as Atlantic croaker and red drum, are caught in droves in the waters of Virginia and the Carolinas but traditionally have been rare north of the Chesapeake Bay.  They were one of the more common species we caught in these two Rhode Island salt ponds, and occurred so consistently that we could actually observe them growing over the course of the summer.  It isn’t unheard of for stray tropical fishes to get swept into Narragansett Bay on Gulf Stream eddies, where they’re either collected by aquarists or die during their first winter.  However, these were populations of spot that we were seeing.  I don’t know if these fish survived their first winter or have come back since I moved down to North Carolina, but even at the very beginning of my interest in fisheries ecology I knew this was odd.

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Largest U.S. Shark Fishery: Coming to a School Lunch Near You?

Spiny dogfish sharks have had a complicated history when it comes to fisheries management, going from hated pest to crashed fishery to conservation concern and now one of two certified-sustainable shark fisheries ever (the other is the Pacific species of spiny dogfish).  The story didn’t end with being certified sustainable though, and recently this fishery has been in the awkward position of keeping itself sustainable while also making sure fishermen can actually sell their catch.  Dogfish quotas have been leaping up annually since the Atlantic fishery was first considered for MSC certification, much to the chagrin of conservationists who would prefer the management plan pay more attention to the life history of these small but slow-growing sharks.  However, these increased quotas, combined with weakening demand in Europe as a result of the economic downturn, have lead to a massive surplus of dogfish in the U.S. market and dramatically lowered the price fishermen receive at the fish house.  Meanwhile, seafood chefs are attempting to get consumers to try out species they’ve previously overlooked (mainly because many of their former favorites are severely depleted), with dogfish sharks among the former “trash fish.”  While this movement gains momentum, fishing industry groups and 19 Senators and House Reps from coastal fishing states are exploring a different option, one that may put spiny dogfish in your local school lunch.

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Good Conservation Policies Can Push Markets Towards Conservation

A lot of debate among conservationists centers on the conflict between the desire to see a species totally protected from human exploitation and the reality that market forces will continue to exist (see the latest on shark fin bans for a very good example).  Ideally, a conservation plan should strike a balance, ensuring the continued existence of the species while still allowing people to profit from it in some way.  This also requires a clear idea of the limitations of conservation policies.  For example, US policies (even the mighty Endangered Species Act) only directly affect populations within the territorial waters of the United States, while international agreements like CITES restrict trade of the species without telling any particular country what to do domestically.  However, there are ways to track the interaction between conservation policies and the market, making it possible to make some predictions on how things like fishery management plans and CITES listings might affect trade.  Then it gets interesting.  Armed with this knowledge, can the market be pushed towards species conservation?

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Predation Matters

Today, Pew unleashed a mini-media blitz on the importance of predation in fisheries management.  This got my attention because the interaction between marine predators and fisheries is one of my major research interests.  They do a great (and slickly-designed) job explaining the basics of why paying attention to predation matters in fisheries management, and bonus points for using the most noble of sharks as one of their examples.  Check out the video here:

 

I particularly like that they go into enough detail to lay out options for incorporating predation into fisheries.  Personally, I’m a big fan of the “second fleet” option, in which predators are counted as another source of fishing mortality (and some of my favorite papers are cited in support of it).  It does require the most effort, but provides the most accurate estimations of predation mortality (and justifies funding for diet studies?  Please?).  Multi-species models are ideal, and really the only way to conclusively prove that trophic cascades are actually happening.  Precautionary buffers, in my opinion, should really follow thorough diet studies, but are certainly another important aspect of ecosystem-based management.

It’s neat to finally see this subject getting some attention.  Here’s hoping the word continues to get out about the importance of shark puke.

 

Circle Hooks Save Fish

When you work on the water long enough, you encounter some unique situations.  Whether it’s getting stranded during field work, surviving massive seasickness, having your equipment attacked by hostile sea life, or just seeing something unusual, these anecdotes are an important part of what makes marine science fun (sometimes moreso in hindsight).  That’s why I’m creating a new category for posts here called “Fish Tales,” where we can share these stories.  To start with, here is a literal fishing story.

While I was down in Morehead City for some field work (post on that coming soon), I got the chance to do a little fishing with fellow Southern Fried writers Andrew and Amy and check on potential sites for shark sampling this summer.  I’d wanted to test out a new fishing rod set up for sharks and large fish, and had rigged up a wire leader with a size 12/0 circle hook.  While casting, it became very clear that I hadn’t properly attached the leader to the swivel when I pulled back an empty swivel where the leader had been.  Frustrating, but I’m practically required to lose gear every time I fish, so I rigged up a second wire leader with a J-hook that was on hand.

Circle hooks are used by recreational and commercial hook-and-line fisheries (and many longliners) to reduce hooking mortality in large fishes, sharks, and bycatch animals like sea turtles.  The idea is that the hook more or less works by itself without being set like a J-hook.  The shape of the hook prevents swallowing and encourages hooking in the corner of the mouth, where it’s less likely to do serious damage.

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Of Fin-Body Ratios and Smooth Dogfish -UPDATED

As you may have noticed from the previous post, the Atlantic States Marine Fisheries Commission (ASMFC) is proposing draft addendum to the Fishery Management Plan (FMP) for coastal sharks to bring it in line with the current Federal regulations.  These regulations are based on the Shark Conservation Act of 2010, which required all sharks fished in US waters to be landed with fins still attached… with the exception of a familiar yet under-studied species known as Mustelus canis, the smooth dogfish.  These sharks can still be finned in Federal waters as long as the weight of fins does not exceed 12% of the weight of the finless carcasses.  This exception was glaring not just because it singled out one species with a relatively limited range compared to other species in the fishery, but also brought out that seemingly absurd 12% fin-body weight ratio.  The addendum is open for public comment until March 28th at 5 pm.  With any luck, this post will help clarify some of the issues involved.

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The Endangered Species Act and Marine Animals: To List or Not To List?

Endangered species seem to be coming up around here more often than usual, mostly due to the potential state-level listing of great white sharks in California.  This move has been resisted from some surprising corners, including researchers who are generally pro-shark conservation.  The reasons why scientists might want to oppose an Endangered Species listing are laid out by Dr. Chris Lowe in an earlier post on this very blog, so I won’t reiterate all of them here.  Surprisingly, I have yet to see any comments accusing Dr. Lowe of being a shill for the drift gillnet fishery.

There seems to a be a real sense among some conservation-minded folks that Endangered Species listing is something of a “holy grail” for species protection and recovery, and some petitioners would have you believe that anything less is unacceptable (and probably the result of corruption).  However, the Endangered Species Act has a very specific process by which species receive protection, and a defined set of limitations.  A lot of well-meaning people seem to have limited knowledge of this process and limitations.  To do my little part to help fix this, this post will be a short primer on the Act and will show how a marine species has recently navigated the entire process for listing.  With any luck, maybe this will result in one or two fewer misguided online petitions.

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Shark DNA Used to Buff Up Aquacultured Fish

It’s not every day that catching up on scientific literature causes you to almost do a spit-take on your laptop screen.  This happened to me recently due to the weird and wild world of aquaculture.  Aquaculture is the practice of growing aquatic animals such as fish and shellfish for the purpose of food, and has been held up as both a savior and destroyer of the marine ecosystem.  To get an idea of what this generally looks like (at least here in the U.S.), Amy has a whole series of posts on aquaculture operations in North Carolina.

As with land-based farming, aquaculturists are motivated to find ways to increase the food value of their stock.  The methods used are varied, from high-protein feed mixes to genetic manipulation.  Recently, farmed salmon genetically-modified to grow larger and faster than their wild conspecifics have been approved for human consumption by the FDA, though not without debate.  This man-made subspecies was created by modifying the already-existing DNA of the fish, but what if it turned out that simply injecting DNA from a different species could improve the growth and protein output of farmed fish?  And what if that foreign DNA came from sharks?

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