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.

An Atlantic sturgeon. Photo credit: NOAA/Robert Michelson
An Atlantic sturgeon. Photo credit: NOAA/Robert Michelson
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New England’s Endangered Living Fossils

Categories: Creature Features

Tomorrow, the US will observe Endangered Species Day, an opportunity to “recognize
the national conservation effort to protect our nation’s endangered species and their habitats.”

If you’re a regular New England Ocean Odyssey reader, you’re probably already familiar with some of New England’s endangered marine species—Atlantic salmon, leatherback sea turtles, and North Atlantic right whales, for example. You also know how important protecting important habitat areas can be to the conservation and recovery of these incredible animals.

In honor of Endangered Species Day, we thought we’d introduce you to one of New England’s weirder endangered species: sturgeon.

There are actually two species of sturgeon found in New England—shortnose sturgeon and Atlantic sturgeon. Once, sturgeon were so common in east coast streams and coastal waters that settlers considered them a navigational hazard, since they tended to leap out of the water and directly into passing boats.

These once-plentiful sturgeon populations have declined sharply since the 1800s due to overfishing for meat and caviar. Shortnose sturgeon have long been considered endangered throughout their entire range, which stretches from New Brunswick to Florida. The Atlantic States Marine Fisheries Commission and the National Marine Fisheries Service placed a coast-wide moratorium on catching Atlantic sturgeon in 1998. In 2012, most populations of Atlantic sturgeon were also placed on the endangered species list, with the exception of the Gulf of Maine population, which is listed as threatened.

Sturgeon are basically living fossils and are one of the oldest existing families of bony fish—they’ve been around since the Cretaceous period, 120 million years ago. They don’t have scales, but are covered with bony plates called scutes. Atlantic sturgeon can reach an insane 60 years old and fifteen feet long. Within the past month, a six-foot sturgeon washed up in the Delaware River and a seven-foot sturgeon washed up in the Connecticut River—and both of these fish were just juveniles.

Atlantic sturgeon are anadromous, meaning they split their time between freshwater and saltwater. Generally, sturgeon remain in brackish streams until they’re about six years old. They then reach maturity in the ocean before returning upstream to spawn. Female sturgeon don’t spawn until they’re about 15 years old and only spawn once every 2-6 years, meaning populations are slow to grow and recover. Sturgeon larvae also need cool, clean, flowing water to survive, making upstream habitat restoration a crucial part of sturgeon recovery.

Interested in learning more about these endangered fish? NOAA is holding an Endangered Species Day Sturgeon Tweet Chat with NOAA Fisheries Scientist Jason Kahn today from 2-3 p.m. ET. Tweet @NOAAFisheries with the hashtag #ESDaychat to join in.

Lined sea anemones off Cape Ann by Alex Shure. http://www.shureunderwater.com/
Lined sea anemones off Cape Ann by Alex Shure. http://www.shureunderwater.com/
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A charming nightmare? With the lined sea anemone perspective matters.

Categories: Creature Features

Look at this tiny wonderland of delicate, star-shaped, fair-haired anemones – benignly filtering food from the water and setting a lovely ocean ambiance. They could be little whisks that a mermaid might use to make a soufflé. Peaceful, right? Wrong. These dudes are remorseless, parasitic death-bringers who drill into their hosts and eat all their food. Which makes me love them a lot, really.

These lined sea anemones (Edwardsiella lineata) spend part of their lives anchored to the bottom of the ocean, doing what most anemones do, sitting around and eating what the current brings them. Before that, however, when they are but wee larvae, they go on a search-and-destroy rampage of their favorite host, a ctenophore known as the sea walnut, or warty comb jelly. We have lots of ctenophores in New England – you can see them in action in this short video by Alex Shure. Ctenophores may seem pretty hardy in this big swarm, but they are no match for the larval lined sea anemone.

 

Jelly Attack! from Green Diver on Vimeo.

It’s not just what this tiny assassin does, it’s how. Mayhem is a polite word for it. As Casey Diederich, my favorite marine biologist for fact-checking blogs about demented goings-on in the ocean, points out:

“The parasitic larva kind of hangs out in/near the pharynx, part of the digestive cavity of the ctenophore, to steal its food. This means that it must have some way to evade digestion by the ctenophore. If you could evade digestion, why not just enter through the ctenophores mouth? Apparently, the parasitic larva burrows through the outside of the ctenophore, then migrates through the ctenophore’s mesoglea (the “jelly” found in  jellyfish, ctenophores, and other kinds of marine invertebrates), and canal system until it gets to the ctenophore’s gut/pharynx. WHAT??? Nature is a crazy motha.”

And, yes, “crazy motha” is a technical marine biology term.

This is probably not much fun for the ctenophore, which can play the unwilling host to several of these baby anemones at a time, but it’s not all bad news, depending on your perspective.

First of all, the parasitic infection prevents the comb jelly from thriving, and thus reduces its population over time. Ctenophores eat zooplankton, including tiny juvenile fish, like cod and flounder. So it’s possible that the parasitic action of the anemone is helping more of these little fish not get eaten and make it to adulthood. More food for us! In some places over half the local comb jellies are infected with the parasitic anemone.

Secondly – in the northeastern Atlantic, off the coast of Europe, these comb jellies are invasive, and really taking a toll on the native wildlife, so the lined anemones might be preventing even worse devastation to the fisheries in that neck of the ocean.

So, the anemones are the good guys? Well, hold on. The larval form of the lined anemone has been implicated as one of the animals that can cause the annoying “sea-bather’s eruption” – an itchy rash you get sometimes after you swim in the ocean. Also, given how successful they are at life in general, there is concern that the lined anemones themselves might become an invasive nuisance in the northeastern Atlantic.

I guess there are no easy conclusions to draw here. Still, I think it’s safe to say that if these types of animals had blood, the lined anemone’s would be cold. One cold-blooded, crazy motha.