Great white sharks off the coast of Massachusetts. (Photo credit: Green Massachusetts)

Let’s be honest. When we talk about great white sharks, we are usually talking about their appetites. White sharks have been found with a number of thought-provoking objects in their stomachs, including a partial suit of armor and an engine block. But what they really like is large, fatty ocean going animals: tuna, seals and sea lions, rays, whale carcasses. These are not always easy to catch, so sharks employ a number of hunting strategies, including a sneak attack from behind (shudder) and rushing up from the depths (double shudder). So, while their feeding style can be quite lively, and more than a little intimidating, scientists believe it is usually a case of “mistaken identity” when a shark bites a human, not mindless, malicious predation. White sharks are visual predators, and sometimes we humans do a fairly good seal impersonation. Often, once the shark realizes there has been a misunderstanding, it will move on to something tastier. Don’t get me wrong; I am not recommending anyone take their chances in the water with these big fish. If there is a shark sighting at your favorite beach, please stay out until you hear it’s safe again. I know they’re out there, but it gives me a bit of comfort to think that if they REALLY wanted to eat us then we’d know about it by now.

Shark survival, and hopefully I’ve convinced you by now that this is a good thing, is dependent on a robust, thriving food chain. Overfishing, coastal pollution (especially nutrient pollution), and the byproducts of power generation are severely impairing our near shore and blue water ecosystems. Coastal areas function as nurseries for ocean going fish, birds, and other marine life. So a small area of degradation can have a big effect out to sea. Protecting sensitive coastal ecosystems is protecting the bottom of the food chain. The things at the bottom feeds the things we like to eat (shellfish, cod, striped bass), the things we like to see (seals, whales), and things we maybe don’t want around, but are good anyway (sharks). CLF is working to protect these important ecosystems. From supporting our National Ocean Policy, to fighting dirty emissions that create unhealthy acidic water, to promoting healthy estuaries, CLF is on the forefront of efforts to protect our oceans and keep their waters clean and productive for generations to come.

A shortfin mako shark, one of the very few warm-blooded fish. (Photo credit: Southwest Fisheries Science Center, NOAA Fisheries Service)

Great whites, makos, porbeagles, and salmon sharks are among the very few warm-blooded fish. I’m not going to hug them, though, since it makes them more efficient predators. Their ability to thermoregulate makes them more tolerant of cool water and allows their muscles to respond more quickly than their cold-blooded relatives. This is just one of traits that make sharks such a diverse and interesting group of animals. Here are some others:

• Most sharks don’t have tongues, but they have taste buds lining their mouths and throats
• Some sharks give birth to live young, but some lay eggs
• Sharks live in saltwater, but some species are able to spend a significant amount of time in freshwater, and have been found as far inland as Illinois (Illinois!), in the Mississippi River
• While they do develop cancer (there is a myth that they do not), it is at a much lower rate than other kinds of fish
• Among the varieties of sharks found in New England waters are basking sharks, spiny dogfish, shortfin makos, blacktip sharks, porbeagle sharks, thresher sharks, sandbar sharks, smooth dogfish, and, of course white sharks

This may seem like a lot of sharks to be swimming around with, but most of them are found much farther offshore than us. A rich diversity of species is a great thing. In ecological terms, diversity can be a sign of the robustness of an ecosystem. If one population is struck down by disease or predation then another can fill the role of top predator. Considering the complexities of species diversity and interactions among them is important when managing the multiple uses of our ocean. This is another great example of why Ecosystem Based Management, one of the core strategies in our National Ocean Policy, is the right tool for the job. Click here to write your Governor today to urge them to support this policy, and healthy oceans for all.

Fun fact: Great white sharks (or white sharks, as scientists prefer) are migratory.

(Photo credit: kqedquest, flickr)

Scientists are just beginning to learn how far ranging an individual shark can be, and they are still puzzling over what motivates them to travel. In Devil’s Teeth, Susan Casey’s fascinating book about white sharks off the Farallon Islands near San Francisco, she describes some of their wanderings. The sharks completely disappear for several months, then return, thin and hungry, to fatten up on local seal and sea lion populations. Some of the Farallon sharks have been tracked to an area off the Pacific coast of Mexico.

What are they doing down there? Nobody knows, but researchers are working hard to find out.  Elsewhere in the book, Casey gives an account of orcas killing and eating one of the sharks. Almost immediately after the killing, dozens of other sharks fled the area. Researchers had been observing them daily, and were very surprised when they all disappeared. One of the sharks had a radio tag on; he turned up in Hawaii.

Our “local” white sharks migrate as well. Like many New Englanders, they head south when the temperature drops, and have been found off the southeast coastal states, and in the Gulf of Mexico.

There is a lot we don’t know about white sharks. But we do know that their numbers are declining throughout the world’s ocean. The average size of the animals is shrinking as well.

This is not good news. Sharks are an important part of a healthy, functioning ocean ecosystem. As we learn more about these mysterious animals, we will need flexible, ecosystem-based management strategies to ensure their survival.

Coastal Marine Spatial Planning (CMSP) is one tool that can help. It is a strategy that is paying off for the endangered North Atlantic right whales. There are very few of these animals left, but they are showing signs of recovery. Recently, shipping lanes were re-routed in Stellwagen Bank National Marine Sanctuary to avoid right whale feeding grounds, allowing for fewer whale/boat collisions. This is just one example of how a strong National Ocean Policy can help provide creative solutions for species conservation.

(Photo credit: NOAA Photo Library)

It’s more of an obsession, really. I spend a lot of time in the water: surfing, boogie boarding with my kids, or just cooling off. I think about sharks every time I get in the ocean. If I haven’t had a good long think about them before I get in, then I ponder their existence as soon as I’ve made it out past the break and I’m dangling my feet off the sides of my seal shaped surfboard. If you meet a surfer who says they don’t think about sharks, they are lying.

So, why the love? Well, I love the ocean. I love a balanced ecosystem. I love eating fish and shellfish. Sharks are one of our more exciting apex predators. An apex predator is the one at the top of the food chain that keeps the populations in check all the way down the line. Recent studies on shark populations have found that a drop in shark numbers leads to plummeting shellfish populations. Sharks eat other predatory fish, as well as rays and other animals that feed on shellfish. Once the sharks are gone, the clams, scallops and oyster populations are preyed on heavily by animals that would normally not be so abundant.  Unfortunately, sharks are declining precipitously around the world. Sharks are taken intentionally for “finning” (the removal of fins for shark fin soup), and unintentionally as bycatch during the fishing of other species. Marine scientists aren’t exactly sure how things would play out if sharks were gone, but none of the scenarios are good.

In “A Sand County Almanac,” Aldo Leopold wrote about one of the apex predators of the west. In his days with the Forest Service there was a mass kill policy for wolves. As a result, deer populations exploded. This led to major overgrazing of mountain vegetation. Erosion and river-choking sedimentation are a couple of the problems associated with overgrazing. Leopold wrote: “I now suspect that just as a deer herd lives in mortal fear of its wolves, so does a mountain live in mortal fear of its deer.” This was a formative part of his land ethic. Simply put “A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise.”

The release last year of our National Ocean Policy (NOP) was a big step in promoting a saltwater version of this ethic. CLF’s Priscilla Brooks had this to say about the newly created NOP: “For the first time in this country’s history, we will have a national policy that aligns the great promise of our oceans with the great responsibility for managing them in a coordinated, thoughtful and sustainable fashion. New England has led the charge to balance the ever-increasing interest in our state waters … with the need to protect wildlife and critical habitat areas so that our region’s oceans will continue to be productive for generations to come. From Massachusetts to Rhode Island to Maine, we are developing ocean management plans that will serve as guides for better protection and management in federal waters across the nation.”

Ecosystem-based management is at the heart of the NOP. Healthy shark populations are just one facet of a balanced ecosystem. Seal populations have been recovering after near decimation from hunting (and a thriving shark population will keep the seals in check). Some commercial fish populations are now recovering from decades of overfishing. Shellfish, seals, sharks, commercial fish – all are linked. We can’t “manage” one without the effects cascading through the others. Ecosystem-based ocean management plans will consider these connections.

So, even as I picture just what it would look like if a great white shark came rushing from the depths for a neoprene-wrapped snack (me), I still love sharks.  I try to be sensible. I avoid the water at dawn and dusk (unless the waves are really good). I stay in shallow water. I get out of the areas where seabirds are working – evidence of major food chain activity. And I’ll take a shark sighting as seriously as anyone. But, since sharks are essential for thriving, productive oceans, they are good to have around. Even if I don’t want them around me.