The edge of an eelgrass bed on sandy bottom. Image via NOAA.
The edge of an eelgrass bed on sandy bottom. Image via NOAA.

Ocean Plants Part 2: Eelgrass

Categories: Guest Posters

Marine plants are the unsung heroes of ocean habitats, providing food, shelter, and substrate to the varied and wonderful animals we love to watch, photograph, or hook on the end of a line. One such plant, eelgrass, or Zostera marina, grows on sandy substrates or in estuaries along the coast and in the sounds of New England. Growing together in long green ribbons, a bed of eelgrass resembles an underwater meadow, swaying in the current.

Eelgrass serves a greater purpose than its beauty, however. Eelgrass beds aid sediment deposition and stabilize the substrate, preventing erosion. They also serve as a home and nursery for both micro-invertebrates and economically important fish and shellfish; a recent NOAA report on the importance of shallow water bottom habitat identified eelgrass as important habitat for juvenile cod, pollock, flounder, and hake, among other species. Eelgrass is also a major food source for several species of marine birds and waterfowl, including brants, redheads, widgeons, black ducks, and Canada geese, and for the endangered green sea turtle.

 

Eelgrass provides essential habitat for numerous fish species. Image via NOAA.

Eelgrass provides essential habitat for numerous fish species. Image via NOAA.

 

Although eelgrass is found throughout the Northern Hemisphere, this essential marine plant is in danger of disappearing from much of its habitat. Several factors are contributing to the decline of eelgrass. Pollution from sewage and fertilizers is a major culprit—it creates an excess of nitrogen in the water, causing algal blooms that block sunlight from reaching the eelgrass and preventing its photosynthesis. Invasive green crabs also harm eelgrass beds by dislodging and shredding stalks of grass as they dig for softshell clams, and green crab populations are growing rapidly in New England. Shellfish rakes, dredges, and boat anchors also destroy eelgrass. In the future, eelgrass faces increased stress from rising ocean temperatures and water levels.

As a result, eelgrass is disappearing rapidly from many of the places it used to thrive, in turn endangering the myriad species that rely on eelgrass for food and shelter, and leading to sediment pollution due to the loss of this important anchor for the marine substrate. Narragansett Bay is one example—once filled with eelgrass, today it has lost 90% of its eelgrass beds.

Yet all hope may not be lost. Since 2001, volunteers and divers working through Save the Bay have participated in eelgrass transplanting efforts. Eelgrass is harvested from healthy beds in the southern end of Narragansett Bay, sorted, and then hand planted by divers, who attach shoots of eelgrass to bamboo skewers and secure the sewers in the substrate. While some of the transplanted beds have failed, others have flourished and spread.

Similar restoration projects are underway in other locations, including Boston Harbor. Efforts to map the current and historical distribution of eelgrass beds are also ongoing in several states and will provide a valuable baseline for future restoration and conservation.

If efforts to mitigate the stresses on eelgrass and restore its original range continue, there is hope for this marine hero—and the abundance of life it supports—to thrive once more.

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Video: Take a 5-Minute Dive on Cashes Ledge

Categories: Cashes Ledge

If only everyone could see and experience the wonder of Cashes Ledge for themselves, we know they would feel as passionate about protecting it as we do. That’s why we’re excited to share with you this new video, filmed with our partner, National Geographic photographer Brian Skerry, Brown University Biologist Jon Witman, and local fishermen. We hope you’ll agree that this video, which features stunning new footage by underwater videographer Evan Kovacs, brings Cashes Ledge to life in a whole new way.

Cashes Ledge is unlike anyplace you’ll find on land or sea – one of the most dynamic hotspots of biodiversity in New England and the entire North Atlantic. But it’s in danger. Cashes Ledge has been protected from the most harmful fishing practices for more than 10 years. But this amazing preserve for fish and ocean wildlife may be just a few months away from having its protected status revoked.

We need your help to make sure that doesn’t happen. You can make a difference for Cashes in just two easy steps:

First, if you haven’t already, please sign our petition to NOAA today, asking them to protect Cashes Ledge.

And second, share this video far and wide with your friends, colleagues, and networks, and ask them to sign our petition and support our work. Because we need many more passionate people like you to take action, today, to protect this remarkable marine refuge.

It’s going to take all of us raising our voices loudly and clearly to protect Cashes Ledge. Thank you for your commitment and for being part of the New England Ocean Odyssey community.

Great white shark off the coast of Chatham this summer.
Great white shark off the coast of Chatham this summer.
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White Sharks Get Top Billing at Chatham Benefit Lecture

Categories: Cashes Ledge | Guest Posters

Hypnotic, elusive, and highly charismatic…. Even at a benefit lecture by a world-renowned photographer and a media-savvy scientist, undoubtedly the great white shark was the star.

Everybody wants to know about this A-lister among fish that makes its seasonal vacation home just off New England’s coasts. So like a feeding frenzy of fans, a sold-out, starstruck crowd packed the Chatham Bars Inn for a joint presentation by acclaimed National Geographic photojournalist and New England Ocean Odyssey collaborator Brian Skerry, and Greg Skomal, senior fisheries expert for Massachusetts Division of Marine Fisheries and director of the Massachusetts Shark Research Program. The lecture was a benefit for the Atlantic White Shark Conservancy.

Skerry opened the evening with “Ocean Soul,” the luminously pictorial, ever-evolving documentation of his travels covering marine wildlife all over the globe. He used a photograph of a baby shark in a mangrove nursery to begin a narration of oceanic habitat in Bimini, where ecosystems of reefs, seagrass beds, and mangrove stands interconnect. “Animals flow between all of these,” he pointed out. Skerry emphasized the absolute interdependence of life in marine habitats: “Every animal plays a role,” he said. “Everything matters.”

That interdependence, of course, includes sharks. Skerry’s global perspective set the stage for Skomal’s thrilling regional focus on sharks in New England’s coastal waters. For of the distinct great white shark populations all over the world – in the northeast and northwest Pacific, around the coast of South Africa, and the coasts of Australia and New Zealand – there is one population of great whites that loves Cape Cod. Teeming grey seal populations due to climatic shifts have over the past decade made the Cape a hot vacation spot for this celebrity predatory jet set.

The frequency and predictability of shark visits to the Cape – one shark nicknamed “Julia” returns on almost the exact same date every year – give researchers the rare advantage of access to these animals.

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Above: Dr. Greg Skomal and his team tracking and tagging great white sharks near Chatham.

Aerial spotters help Skomal and his team locate the sharks. Once a shark is spotted, the challenge of tagging begins, with a biologist balancing on the pulpit of a boat to lance the fish’s dorsal fin with an electronic tag via an intramuscular dart. Buoys and receivers on the ocean then create transects that collect data about sharks in the area.

New technology has given researchers more access to sharks, through acoustic tags, pop-up satellite tags, and AUVs (i.e., drones) – autonomous underwater vehicles that send back revealing videos of shark behaviors.

“We know that they are dynamic and highly migratory, with complex migratory patterns,” said Skomal. “They are warm-bodied, so they can go anyplace they want. They are far more remarkable than we had ever imagined.”

But for all we have discovered about sharks, there is still so much we don’t know. “We are just getting started with studying these animals in this area,” said Skomal, who has been concentrating almost exclusively on shark research for the last six years. He invited young people fascinated by the sea to consider a career in shark science, which offers ample opportunities for exploration, such as solving the mystery of white sharks’ 800-meter-deep dives off of the continental shelf. What are they doing down there?

Skomal emphasizes the importance of sharks as apex predators for maintaining sustainable fisheries. Just like terrestrial predators picking off the sick and weak members of a herd, sharks keep fish stocks healthy by predating the less viable members of a fish school. So they are in fact allies of fishermen, being fishermen themselves!

Skomal’s research on the migratory pathways of these formidable fish could be a valuable resource for policymakers in the creation of protected areas where sharks can be safe from hunting and harassment, in order to replenish their populations so critical to the balance of a healthy ocean ecosystem. Every animal matters.

And his advice for humans sharing the water with these grand and intimidating animals? Show common sense and healthy respect. And don’t swim in the deep channels close to shore.

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

The Ocearch crew tags the great white Mary Lee. Image via Mass EEA.
The Ocearch crew tags the great white Mary Lee. Image via Mass EEA.
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How to Tag a Great White Shark

Categories: Guest Posters

With the help of over 50 researchers from more than 20 institutions, the non-profit Ocearch has tagged and tracked sharks around the world, from South Africa to the Galapagos. In September 2012, this research mission came to New England for the first time when the great white shark dubbed “Genie” was tagged off of Chatham in Cape Cod, MA.

What does it take to wrangle one of the fiercest apex predators in the ocean? After hours of preparation, sport fishermen and scientists from Ocearch set out each day on the repurposed crab vessel M/V Ocearch, a boat about the same size as the sharks they’re searching for, and use chum to attract sharks while they scan the ocean surface.

Once sighted, a shark is baited and hooked, guided towards the Ocearch vessel, and hauled out of the water using a custom lift capable of supporting thousands of pounds in weight (great whites can weigh over 5,000 lbs).  The Ocearch captain jumps into the water and onto the platform with the shark and uses the shark’s tail helps to guide it onto the lift.

When the team pulled Genie on board and the water around her receded, her anxiety visibly increased, so Ocearch Captain Brett McBride threw a wet towel over her eyes. As she began to calm down, the Captain was able to remove the hook from her mouth and insert two hoses to cascade water over her gills. At this point the rest of the crew jumped onto the platform, sporting jeans and long-sleeve shirts, and began to take a series of measurements and tag Genie. Named for “the shark lady” Eugenie Clark, Genie measured at 14 feet, 8 inches and 2,292 pounds.

Using a power drill, Genie’s dorsal fin was fitted with a satellite tag, an accelerometer and an acoustic tag. Other researches collected blood and tissue samples to study back in the lab. Genie was out of the water for approximately 15 minutes before she was guided back into the ocean and the tracking began. 10 hours later, the accelerometer detached from Genie, floated to the surface and transmitted data regarding her swimming pattern and movements. Whenever Genie’s dorsal fin breaks the surface, her tracker transmits a signal to a satellite overhead, which produces an estimated geographical location for the shark. Where is Genie now? Enjoying herself on Virginia Beach, VA.

As of this summer, the “shark wranglers” working for Ocearch have successfully tagged well over 50 great white sharks around the globe. By tracking sharks like Genie, researchers are hoping to build an understanding of their migratory patterns, breeding grounds, birthing sites, feeding areas and general white shark behavior. This information will help protect some very important animals—great whites are apex predators, which means a healthy population is crucial to maintaining the balance of ocean food webs and ecosystems.