Scalloped hammerhead sharks. Image via Daniel Kwok, Flickr.
Scalloped hammerhead sharks. Image via Daniel Kwok, Flickr.

Protecting Sharks

It’s been a good summer for shark conservation. On July 24th, Massachusetts Governor Deval Patrick signed a bill banning the possession and sale of shark fins in the state. While the 2010 Shark Conservation Act passed by Congress had prohibited shark finning and required sharks harvested in state waters to be brought to shore whole, it did not eliminate the market for imported shark fins in the U.S., where shark fin soup is sometimes priced at $100. With Massachusetts’ ban in place, a total of nine U.S. states and three U.S. territories have now joined in efforts to eliminate finning altogether.

Last month, scalloped hammerheads made national news when the species became the first shark to be placed on the U.S. Endangered Species List. The scalloped hammerhead is threatened by the commercial fishery for its fins—the sharks are highly valued in the fin trade because of their fin size and high fin ray count. They are also caught as bycatch by offshore longlines and gillnets.

This shark is found in warm and temperate waters across the globe; four scalloped hammerhead shark populations were placed on the endangered species list. The Eastern Atlantic and Eastern Pacific scalloped hammerheads were listed as “endangered,” and the Central & Southwest Atlantic and Indo-West Pacific scalloped hammerheads were listed as “threatened.” This listing prohibits the catch, sale, and trade of scalloped hammerheads in the United States.

These actions are a win for shark conservation, and they build on other state and federal protections for the approximately 400 shark species in the world, about 40 of which are found in U.S. waters. In New England, there are at least 26 shark species protected by state catch limits, size minimums, types of equipment permitted for use or a prohibition against their harvest. Some of the popularly-known protected sharks that cannot be harvested in New England include the great white (Carcharodon carcharia), basking (Cetorhinus maximus), longfin mako (Isurus paucus), and sand tiger shark (Carcharias Taurus).

Why protect the feared kings of the sea? Well, first of all, they’re just cool, and as this video shows, they’re not as dangerous as most people think.

Sharks also play a critical ecological role as the ocean’s apex predators.

Unfortunately, sharks take a relatively long time to grow to maturity, produce few offspring, depend on wide swaths of intact ocean habitat, and are very sensitive to ecosystem changes.  All of that means they’re exremely vulnerable to the effects of overfishing and habitat loss. Nearly half of the shark and ray species assessed by scientists for the International Union for Conservation of Nature are threatened or near-threatened with extinction, and around 100 million sharks are killed every year in commercial fisheries.

So while there have been some steps in the right direction, there’s still plenty more we can do to protect these great ocean fish, from research to habitat protection to improved fisheries management and bycatch reduction. The health of our marine ecosystems depends on it.

A great white shark circles gray seals off Chatham, MA. Photo via Mass. Office of Energy and Environment
A great white shark circles gray seals off Chatham, MA. Photo via Mass. Office of Energy and Environment

The Ocean’s Top Predators

In “Ocean Soul,” world-renowned National Geographic photographer Brian Skerry says, “It’s been said that sharks have remained unchanged for hundreds of millions of years because they are perfect and that no further evolutionary change is necessary.”

Sharks have certainly reached the top of the food chain as the ocean’s apex predators. Apex is a word of Latin origin meaning peak or tip. In ecological terms, apex is used to describe an animal that has no natural predator within its ecosystem—terrestrial examples include wolves and cougars.

Although humans might find them terrifying, apex predators are crucial for maintaining healthy ecosystems. Sharks, for example, play a vital role in balancing ocean food webs. They aid in population control of smaller predators, so that prey species are able to exist at healthy levels. They also regulate the behavior and abundance of prey species, protecting habitat like seagrass beds and coral reefs from overgrazing, and promote biodiversity by preventing any single prey species from monopolizing resources.

Sharks also tend to prey on weak or sick members of a species, so as to minimize their caloric hunting expense. This natural tendency towards efficiency promotes healthier populations by advancing the transmission of strong genes, as weaker genes are taken out of the gene pool.

Despite the enormous amount of good we know sharks do for ocean ecosystems, humans hunt sharks for their meat, especially their fins. Sharks can also become collateral damage to commercial fishing for other species—accidental net entanglements or hooking often prove lethal. According to a 2013 report published in “Marine Policy,” humans killed approximately 100 million sharks in 2000, and 97 million in 2010. Annually, humans kill between 63 and 273 million sharks.

What happens when the oceans begin to feel the loss of sharks? Populations of smaller predator species boom, stressing habitats and depleting populations of prey species. These changes can be very detrimental to the fishing industry. For example, depleted great white shark populations have been linked to the boom in gray seal numbers in New England, and the voracious appetite of the seals may be harming the recovery of overfished cod. In North Carolina, a decline in large sharks because of overfishing led to an increase in cownose rays, one of the sharks’ prey species. Cownose rays eat shellfish, and so an increase in their population caused the bay scallop fishery to collapse.

Clearly, apex predators like sharks are absolutely critical to maintaining healthy marine ecosystems. The role of apex predators is better understood today than ever before, and now that we know how vital their role is, it is time to protect and respect the ocean’s top predators.

A great white swims in a Cape Cod salt pond in 2004. Image via Mass EEA
A great white swims in a Cape Cod salt pond in 2004. Image via Mass EEA

Gearing Up for Shark Week

The Discovery Channel’s Shark Week starts in just ten days! As ocean fans around the world gear up for the annual celebration of all things shark, New Englanders are turning their eyes to the North Atlantic Great white population. It seems these days Cape Cod beachgoers can’t help but scan the ocean horizon for a dorsal fin before taking a chilly but refreshing dip.

This year’s Cape Cod shark-spotting season kicked off on June 23rd when Captain Tyler Macallister captured video footage of a great white, Carchardon carcharias, six miles southwest of Provincetown, in Cape Cod Bay. Upon seeing the shark, Macallister began recording his calm and somewhat mystical encounter with the estimated 16-to-18 foot great white. A Massachusetts Division of Marine Fisheries biologist confirmed that the fish captured on Macallister’s video camera was a great white, but that the lack of scale in the footage meant its size could not be accurately determined.

Five days after Captain Macallister’s encounter with a great white shark in Cape Cod Bay, researchers from the Atlantic White Shark Conservancy saw a great white one-quarter of a mile off of Nauset Beach, near Orleans, Cape Cod. The researchers were able to identify the fish as a 12-to-14 feet long female great white and named her “Ping.” Ping was first spotted by a spotter plane and then tracked by boat. The Atlantic White Shark Conservancy sends out both a spotter plane and boat twice a week to study Ping and other great whites.

The increase in great white shark sightings has been going on for the last decade or so, and in the Cape Cod area it’s been partially attributed to the growing gray seal, Halichoerus grypus, population around the Cape. Gray seals were previously hunted by fishermen as a precaution towards preserving fish populations that the Gray seals consume, but the seals are presently protected by the Marine Mammal Protection Act of 1972. Great white sharks prey on seals and as seal populations expand in the Cape Cod area, there appears to be a growing number of white sharks.

If you are curious where these sharks spend their days, when they are not busy stalking Cape Cod’s massive seal populations, you can track tagged sharks through Ocearch.com or through the Ocearch app. And get ready for more information on New England’s sharks as we celebrate Shark Week here at New England Ocean Odyssey!

A striped bass fisherman on Chappaquiddick. Image via John Piekos, Flickr
A striped bass fisherman on Chappaquiddick. Image via John Piekos, Flickr

Striped Bass and Forage Fish

As the summer heats up along Atlantic coast, coastal residents and visitors alike head out in boats, stake out spots on docks and bridges, or don rubber waders and forge into the waves along a beach’s breakwater. Each is armed with a long pole and a zeal for the chase. Their quarry is the striped bass, a silvery fish with trademark dark stripes running the length of its body from head to tail. The striped bass, or striper, is an anadromous fish native to the Atlantic coast of North America, and usually grows to around three and half feet. The historic abundance of the striped bass, as well as its ideal size for recreational fishing, makes it a highly valued sport fishing species. In 2004, recreational fishermen landed more than 2.5 million stripers.

Unfortunately, recent evidence indicates that this time-honored recreational fishery may be in danger of collapse. Recreational fishermen in Massachusetts reported a staggering 85% drop in striper numbers between 2006 and 2011, and Massachusetts is not alone: states up and down the coast are seeing fewer stripers, and the schools of bass that migrate up the coast from the Chesapeake Bay to Maine are thinning out. More and more fishermen are heading home empty-handed at the end of the day, and more importantly, the disappearance of the striped bass leaves a lack of an important member of the marine ecosystem and food web.

Image credit: Timothy Knepp/Wikimedia Commons

Image credit: Timothy Knepp/Wikimedia Commons

Many factors are responsible for the decline of the striper, but one is often overlooked: food. Small forage fish, including Atlantic herring and river herring, compose around 90% of the striped bass diet, and these forage fish face the pressure of a significant fishery of their own. While ignored by recreational fishermen, Atlantic herring are heavily fished by commercial fishermen, largely for use as bait in the lobster industry. In 2011, for instance, U.S. commercial fishermen harvested over 174.3 million pounds of Atlantic herring.

Recent assessments indicate that Atlantic herring are not overfished, but surveys of population levels and safe catch limits rarely take proper account of the amount of a forage fish required to feed its predator species. As a result, after the herring fishery has hauled in its 170 million pounds of fish, there may not be enough herring left to both maintain a steady herring population and provide the striped bass with sufficient prey.

River herring, meanwhile, have been depleted by years of overfishing and habitat loss due to dams. Total landings of commercially fished river herring have decreased steeply over the years: in the 1950s, over 60 million pounds of river herring were harvested by commercial fisheries throughout the US, but this number had decreased to around 2 million pounds by 2012. In response to this decline, many states have implemented moratoriums on intentional catch of river herring and have made strong efforts to remove dams and restore upstream habitat; river herring runs in many New England rivers seem to be on the rebound. But river herring are still at risk at sea, where they are caught as bycatch by the Atlantic herring and mackerel fisheries.

This scarcity of prey spells danger for the striped bass. Without sufficient forage fish, there will be fewer striped bass in the sea, and more fishermen with empty hooks.

Blue crabs. Photo via Benjamin Wilson, Flickr
Blue crabs. Photo via Benjamin Wilson, Flickr

Crab Chowder?

In 2012, northeast sea surface temperatures reached an all-time high. Many speculate that rising water temperatures have contributed to a record high catch of 126 million pounds of American lobster, Homerus americanus, in the Gulf of Maine. However, the steady rise in New England’s sea surface temperatures may have also made southern areas of New England inhospitable for lobster. In a recent interview with AccuWeater, Maine Lobstermen Association’s Patrice McCarron said, “In southern New England, Buzzard Bay, Mass., and the waters off of Rhode Island, temperatures in the Long Island Sound area have become too warm for lobsters.” Lobster catch in these areas has plummeted since the 1990s.

The warming trend in New England waters has caused alarm for local fishermen, and we’re only beginning to understand the ways climate change might affect our fisheries. While some treasured New England species may relocate father north, it’s possible that other species will move into this region and create new economic opportunities.

We’ve written before about some of these species moving north as water temperatures rise, and now we can add another to the roster—blue crabs. Although blue crabs are traditionally caught off Maryland and Virginia, fishermen in Long Island Sound have been seeing more of them lately. Some think that, in time, Long Island Sound could replicate the blue crab fishery of southern areas like Chesapeake Bay.

The blue crab, Callinectes sapidus, whose Latin name can be translated to mean “beautiful savory swimmer,” is the Maryland state crustacean and the most valuable shellfish in the mid-Atlantic region. The crabs can grow to be around 4 in long and 9 in wide, weighing around 1 pound, and reaching maturity in 12 to 18 months. The bottom-dwelling blue crab can live in a range of salinities, feeding off of crabs, claims, snails, eelgrass, sea lettuce and decayed vegetation. Blue crabs can be found all along the Atlantic Coast, with a prominent population in Chesapeake Bay presently suffering from habitat degradation and overfishing.

Could Maryland’s pride species create a new industry in New England Waters? The blue crab, caught for sale in both hard and soft shell forms, is currently sold at a market price in Maryland of $39.25 per dozen. With the growing blue crab population and a high demand market, does New England clam chowder have a new competitor on the way?

Scientists are careful to note that the long-term effects of climate change on species like blue crabs are still far too uncertain to predict the future of a fishery, but one thing is for sure—New England’s ocean is changing, and marine life is on the move.