Sustainable Insights          

By JAY LINDSAY, Associated Press Writer
Fishery managers trying to protect rare sea turtles from dying in fishing nets have tapped a Cape Cod company to build a device they think can help balance turtle protection with profitable fishing.

The “tow-time logger” is a 7-inch, silver cylinder that attaches to fishing nets and records how long the net stays underwater.

That time is crucial if a turtle gets snared in the nets dragged behind fishing trawlers. Federal research indicates the vast majority of sea turtles survive entanglement — but only if the net is pulled up in less than 50 minutes.

With the logger, regulators can avoid other, potentially more onerous, restrictions on perpetually struggling fishermen — such as shutting down fishing areas or requiring turtle-saving gear that doesn’t work well in all nets. In fisheries where they decide time limits would work best, they wouldn’t have to depend on an honor system to make sure nets are pulled up in time.

“Turtles have also been around since the time of the dinosaurs,” said Elizabeth Griffin of the environmental group, Oceana. “They’re cool animals that I think most people want to see continue to exist.”

The logger was built under a $25,000 federal contract with the National Oceanic and Atmospheric Administration by Onset Computer Corp., a Bourne-based supplier of data loggers for energy and environmental monitoring. It starts recording water depth every 30 seconds once the net drops below two meters. If the net stays under beyond a preset time limit, the logger records it, and the infraction can be discovered when regulators download its data.

The device’s early tests at sea have been successful, and work is ongoing to toughen it for the real-life rigors, such as being banged on fishing boat decks. The company expects it to cost between $600 and $800, an expense that would fall to fishermen.

Even when the logger is perfected, regulators know limiting how long the nets stay underwater is no cure-all as they devise rules, which they hope to propose for public comment by 2010, to meet a new federal requirement to protect sea turtles from trawler fishing nets.

Some environmentalists say turtles shouldn’t be kept underwater at all because even relatively short times of being trapped underwater without oxygen hurt them.
Griffin says there’s also not enough data on how trapped turtles fare in colder waters, so no one really knows how long they can be kept under and survive.

The data logger at least makes briefer tow times a feasible way to protect turtles, if researchers can sort out what’s safe, she said.

Fishermen are skeptical. They say short tows aren’t practical in most fisheries, such as those in deeper waters, where a worthwhile catch is impossible if the nets must constantly be pulled up.

“It’s a bad idea,” said James Fletcher, a veteran fisherman and now head of the North Carolina-based United National Fisherman’s Association.

“Nobody’s going to love the idea,” acknowledged Henry Milliken, a biologist with the National Marine Fisheries Service, which is part of NOAA. But he added fishermen might prefer limits on how long the net can be underwater to harsher alternatives, such as closing fishing areas.

“The idea is that we’re looking at providing options to the managers in the future,” Milliken said.

As the NMFS tries to determine which steps will or won’t work, it’s held public meetings this spring from New York to Georgia.

The turtle most frequently caught in trawl nets in the Atlantic is the loggerhead, the threatened 250-pound giants named for their relatively large heads. In U.S. waters, every sea turtle is listed as either endangered or threatened, so any turtle deaths in fishing nets hit the populations hard.

The most common way to protect turtles right now is the Turtle Excluder Device, often a circular, barred frame attached near the front of fishing nets. The bars are big enough for fish and other sea life to slip through, but too narrow for turtles, which bounce out of the net before they get caught.

The excluder devices have had success in some fisheries, including the Southeast’s shrimp trawl fishery, but bigger species, such as horseshoe crab, monkfish and flounder, can bounce out along with the turtles and make the nets far too inefficient.

Greg DiDomenico of the Garden State Seafood Association, a New Jersey trade group, said since the new rules will apply to fisheries from Cape Cod to Florida — where the turtles swim — whatever shakes out is bound to be felt industry-wide. That includes “huge negative impacts on some fisheries,” he said.

But with regulations coming, DiDomenico said his best hope is that regulators don’t broadly force a turtle-protecting solution, including the time logger being developed, on a diverse fleet.

“It’s not one-size-fits-all,” he said.

For several years, loss of live coral habitat due to coral bleaching has become a global concern prompting researchers and scientists to study the health of coral reefs around the world. One location affected by this phenomenon is the southern Seychelles Islands, in the central-western Indian Ocean, north of Madagascar.

Coral bleaching has been linked to rising ocean temperatures causing 40 to 50 percent of the coral in this region to become colorless and vulnerable to a variety of environmental stresses. To better understand the effects of rising water temperature on the coral’s ecosystem, researchers are using HOBO® water temperature data loggers as part of a long term monitoring program.

“Coral reefs are one of the most productive ecosystems on the planet – equal in many respects to tropical rainforests and they are a very important component of the ocean’s ecosystem,” explains Ray Buckley, a Principal Investigator with the Aldabra Marine Programme (AMP). “So when you have a coral bleaching impact, it has a major effect on local and regional ecosystems.”

“The main focus of our research is Aldabra Atoll because it’s a large remote coral reef ecosystem which has received little impact from human habitation. It is one of the last natural laboratories on the planet. What happens there is how nature really responds to an environmental impact.”

To monitor water temperature, Buckley and the AMP team have strategically placed HOBO Water Temp Pro data loggers in several locations at Aldabra Atoll, and Assomption, Astove and St Pierre Islands to the east. Each data logger is deployed using cable ties and stakes, and water temperature measurements were taken every 30 minutes to an hour.

“The data loggers have become encrusted with bioaccumulation of coralline algae after two years on the reef and are still able to collect accurate temperature data,” says Buckley.

The data logger provides ±0.2°C accuracy over a wide temperature range and offers a 42,000 measurement storage capacity, making it suitable for long-term deployments.

Data from the loggers can be quickly offloaded directly to a laptop via a USB-based optical interface, which provides high-speed, reliable data offload in wet environments. Its optical design eliminates the need for failure-prone mechanical connectors found in many traditional underwater data logger products.

The data was analyzed using HOBOware® Pro graphing and analysis software, which easily converts the collected data into easy-to-read graphs that reveal spikes and drops in water temperature over a 12-month period.

“Most coral bleaching studies take place in locations where there are major impacts to the corals due to human development,” explains Buckley. “While those studies are critical in better understanding coral reef health, they are unable to provide a good baseline for how an ecosystem responds when there is no human impact. Aldabra Atoll is as close to pristine as we have and allows us to see how the coral and fish respond to the rising temperatures without outside interference.”

Researchers have found that, in coral reef ecosystems impacted by human development, there is usually a shift in the dominant component of the ecosystem from live coral to algae.

“The fish populations then switch to mainly herbivorous species and the algae covering the dead coral makes it harder for the coral to recover. This causes a major shift in reef ecosystem,” says Buckley.

According to Buckley, for the past 10 years, there were no substantial changes to the fish populations at Aldabra Atoll where there was essentially no human habitat.

“The coral bleaching event did not result in an algae dominated ecosystem and it wasn’t catastrophic for the fish in this area. Fish were able to adapt to the rapid major loss of live coral habitat and development of a new coral habitat. We found that if there were no other variables affecting the ecosystem, fish can respond positively to these habitat changes, even though the matrix of the system changed.”

UNH Ph.D. candidate Jason Goldstein holds a lobster with a temperature logger, an ultrasonic transmitter and a return tag. These items are secured to the lobster like a lightweight backpack to help UNH researchers learn about their migration patterns. Credit: Rebecca Zeiber, N.H. Sea Grant

Jason Goldstein checks his lobster traps in New Hampshire’s Great Bay Estuary once a week, but not for tasty crustaceans to sell. Instead, the University of New Hampshire Ph.D. candidate is fitting these lobsters with transmitters and tracking their migrations year-round.

Goldstein has tracked lobsters along the New Hampshire coastline and into Great Bay throughout the past two years. This research, funded by N.H. Sea Grant, will provide more accurate information about the sources of juvenile lobsters and interactions between the population stocks in New England. The information could improve the management of this economically valuable fishery, thus allowing lobster to remain front-and-center among the New England menu choices.

Goldstein and UNH professor of zoology Win Watson are particularly interested in the movements of “berried” females, those carrying eggs. This year, they are comparing the berried females’ movements with those of the large- and small-sized males and females without eggs. Where the berried females go, so go their eggs, and those movements likely have implications for New England lobster populations.

“We often go diving one day and there are a lot of lobsters around, and the next day they’re all gone and have moved offshore,” Watson says. “There’s a dramatic shift that takes place in late autumn and causes them to move out into deeper water.”

Watson and other researchers believe this drive to migrate is primarily due to water temperatures. The deep offshore waters are consistently warmer in the winter and cooler in the summer than shallower water close to the shore, Watson explains. Lobster migrations might also be driven by turbulence in the water, particularly during autumnal storms.

“They are very mobile animals and move around to avoid bad conditions,” Watson says. He notes that the average lobster can walk from the Isles of Shoals to the New Hampshire shore — up to 10 miles — in just a few days.

Along with other students and technicians, Goldstein has spent numerous hours tracking the lobsters using ultrasonic and handheld hydrophone tracking equipment to locate them and determine their movements. Commercial lobstermen are assisting Goldstein by helping to tag some of the creatures they find in their traps. In many cases, lobstermen who capture tagged lobsters will call Goldstein to report the tag number and location.

In addition, 15 “lobster listening stations” moored throughout Great Bay and the coastal waters allow researchers to more accurately pinpoint where the lobsters go. These stations hold special ultrasonic receivers that can identify and record tagged lobsters moving within a 400-meter radius of the equipment. For example, receivers are currently located at the Great Bay Marina, the Shafmaster dock, the Public Service of New Hampshire power stations, and the Weathervane dock in Portsmouth.

The various tracking efforts have led to a wealth of knowledge. Watson originally hypothesized that berried females would be more likely to move offshore to protect the eggs during the winter months. However, he was surprised to find out that most lobsters, regardless of size, gender or maturity, followed the same migration patterns.

The researchers also learned that relatively few berried females are located in the estuary, while male lobsters are often found there. Goldstein and Watson theorize that the estuary is too extreme an environment for most females carrying eggs, so they migrate toward the ocean when they reach sexual maturity.

In addition to studying the migrations of the adult lobsters, Watson and Goldstein are using oceanic drifters — submerged box-like structures that mimic the movements of lobster larvae — to learn how the movements of berried females could impact where larvae are released and the path they travel when carried by ocean currents during the three weeks they are in the water column prior to settlement. They’ve found the drifters, which are fitted with satellite transmitters so they can monitor them remotely, travel as far away as Cape Cod and Georges Bank. However, those released in Great Bay estuary tend to remain there, likely to the detriment of the lobster populations.

“The estuary is not the best place for lobster larvae because of the warmer temperatures, higher turbulence and lower salinity,” says Watson. “That might explain why there are few mature females there.”

Putting all these data into perspective will be Watson’s next step. He hopes to apply what he has learned to improving management practices for the species. In particular, Watson wants to know if New Hampshire lobsters can be managed in isolation or if the management unit needs to be larger.

“If our lobsters are leaving for Massachusetts or elsewhere, then we need to work together to better manage the population,” he says.

Onset’s TidbiT® temperature data loggers are helping researchers understand the effects of water temperature conditions on the fish population in Colorado’s Bear Creek.

Karen Christopherson, a volunteer researcher for Evergreen Trout Unlimited, has been using TidbiT loggers for the past several years to monitor rising water temperature conditions. “We are monitoring the stream temperatures in order to show that temperatures vary significantly,” explains Christopherson. “At times, temperatures exceeded the EPA mandated temperature limits for cold-water fisheries. We had noticed a fish die-off in 2000 and 2002, during high water temperatures.”

In order to prove their case that water temperatures were rising, and prompt action by the EPA, state, and the local agencies, Christopherson and her team placed the loggers in various stream locations to monitor temperature conditions at an hourly rate.

“So far, we have succeeded in getting cooperation of state and local agencies to help the stream. This benefits not just the trout, but all other wildlife, as well as the community. It all started with our Trout Unlimited group gathering temperature data with the TidbiTs in order to prove our point – that stream temps were too high,” concludes Christopherson.

Onset’s TidbiT® temperature data loggers are helping researchers understand the impact of water temperature on the survival and growth of oysters along New England’s coast.

Researchers at the Woods Hole Oceanographic Institute (WHOI) are studying five strains of New England oysters bred for disease resistance or chosen from disease resistant stock. These strains are grown alongside one another at four sites throughout New England.

John Murt, a researcher at the Marine Biology Laboratory at WHOI, has been using TidbiTs to monitor temperature conditions at all of the growout locations. “Prior to using the loggers, our team would take monthly field sampling trips to each site to record environmental data as well as growth and mortality of each oyster strain,” explains Murt. “Without the data loggers, we would only have a single monthly water temperature recording instead of the daily samples we collect with the loggers.”

The loggers allow Murt and his team to record water temperatures year round without having to rely on someone being in the field collecting data manually. “With temperature being the driving factor of water-borne bacteria, the data set provided by the loggers is essential for us to better understand when the conditions are right for these bacteria to impact either oyster populations or oyster farms,” says Murt.

According to Murt, similar research for Quahogs will start this summer. Three strains are currently being grown in hatcheries and will be seeded into growout patches in local harbors.

“The manpower saved by deploying data loggers means that we get a much better data set for a lot less effort. This is a win-win situation for everyone,” concludes Murt.