ROVworld Subsea Information

Scientists perform fish surgeries, use ROV to study Florida Keys’ underwater world
Date: Sunday, October 05, 2014 @ 12:44:46 EDT
Topic: GENERAL NEWS


 

As a 365-pound remotely operated vehicle was being deployed from the deck of the Nancy Foster, a group of curious onlookers showed up from the deep blue.

“Oh, look, dolphins,” Ensign Felicia Drummond exclaimed in delight to Jeff Shoup, commanding officer of the NOAA coastal research ship.

Eight Atlantic spotted dolphins were swimming around the bright yellow, alien-looking creature that had just entered their water playground in the Dry Tortugas, the most remote part of the Florida Keys.



“I’ve never seen that happen before,” said Jason White, the pilot of the remotely operated underwater vehicle (ROV).

While dolphin research wasn’t part of the scientific plan for this cruise, which ran Sept. 14-27, the magical two minutes captured by the ROV’s video camera provided the Florida Keys National Marine Sanctuary with a hook to lure the public onto its social media sites. After clicking on the cute dolphins video, people also could learn more about the marine science being conducted to ultimately help shape future sanctuary and fisheries management policy.

It quickly became evident during the Nancy Foster’s two-week mission that science at sea — especially in a remote location, 70 miles west of Key West, where the only man-made structures are a Civil War-era fortress and a lighthouse — is a slow, collaborative effort. One that requires scientists to exhibit the same kind of curiosity as those dolphins did.

Exploration included parts of the seafloor, down to 420 feet deep, that had never before been seen by humans. No big discovery was made, but none was expected. Instead, lots of tiny pieces were collected to become part of a complex, evolving puzzle that began to take shape a few decades ago as it became evident that while the oceans seem endless, their resources are not.

The cruise — which included fish surgeries, homemade lionfish ceviche and the discovery of a sunken shrimp boat teeming with protective Goliath groupers as big as Sumo wrestlers — started at the U.S. Coast Guard station in Key West, where the Nancy Foster docked to give its crew of 22 a port call and to pick up the new science party of 15.

For the first half, the science party included Sean Morton, superintendent of the Florida Keys National Marine Sanctuary, chief sanctuary scientist Scott Donahue, dive master Brett Stafford, seven scientists from the Florida Fish & Wildlife Conservation Commission, two ROV pilots, a science member of the NOAA Commissioned Corps and Amy Orchard, a museum educator from Arizona participating in NOAA’s Teacher at Sea program.

The Nancy Foster, a 187-foot ship that looked like a giant white tugboat, was built by the U.S. Navy as a torpedo tester called YTT-12. When it was completed in 1991, it already was not needed.

“It went straight to the mothball fleet, in dehumidified storage,” said chief engineer Tim Olsen, the only crew member who has been with the Nancy Foster since its commissioning in 2004. “That was good for NOAA.”

In 2001, the Navy transferred the mothballed ship to the National Oceanic and Atmospheric Administration, which invested $7.7 million to transform the torpedo tester into a floating field laboratory primarily used by marine scientists.

On the first day of the research cruise, the ship left Key West in the morning to make the hours-long trek out to the Dry Tortugas, which includes seven small islands, the Dry Tortugas National Park, two federally protected ecological reserves and the state’s natural protected area. That afternoon, from small boats launched from the ship’s main deck, scientists from FWC’s Fish and Wildlife Research Institute office in Marathon dove 100 feet to set up fish traps at two locations.

The divers, who had special research permits, were trying to catch commercially and recreationally important reef fish that could be surgically implanted with acoustic tags to track their movements.

On day two, scout dive teams were sent to the traps to see whether they had captured any fish worthy of tagging. The first team swam through a strong current and a thermoclime to get to the bottom, only to find an empty trap. The second scout team also had no luck. Both traps were left in place to “continue fishing.”

Next, the ROV was launched at an area of Riley’s Hump, sort of an underwater oasis for fish surrounded by water more than 1,000 feet deep in the South Ecological Reserve, where fishing, diving and anchoring are prohibited.

The ROV, with a long fiber-optic umbilical cord attached to equipment on the ship, traveled this time to about 250 feet, still too deep for most scientific divers. Most of the scientific party gathered in the wet laboratory to watch the ROV images being sent back to the ship in standard and high definition, and in real time.

There was great controversy in 2000, when the popular fishing grounds were closed. The intent of the South Reserve, as well as the nearby North Reserve, was for the protection of 151 square nautical miles of prime spawning grounds and nurseries to allow the important fish populations to recover and to remain sustainable.

Shoup, who studied chemistry in college, said he enjoys the scientific missions that remind him of the line, “We’re trawling for Atlantis,” in the Billy Joel song: The Downeaster “Alexa.” “It’s kind of fun what we’re out here doing,”

Shoup said, “looking for the next new thing.”

Chief engineer Olsen, who spent 20 years in the Army working on ships, said working on a research ship has made him care much more about what’s in the ocean. He recalled research that was conducted on sperm whales because they were being struck in great numbers in a shipping lane leading in and out of Baltimore. “The science showed it was part of the whales’ natural migration route,” he said. “They changed the shipping lanes, and I don’t think there has been a single strike since.”

That project took years. Science and the government move slowly, just like the ROV that was cruising above the habitat at about 1/4 to 3/4 knots.

At the depths of more than 200 feet, there was none of the lush, vibrant coral you see in shallower parts of the reef. But the structure that looked like old rock housed a thriving ecosystem with cubera snappers, black groupers and amberjacks showing up in abundance and in large sizes.

“This is a good spot to monitor,” said Paul Barbera, research associate with FWC. “There is a lot of fish that are just impressive in size, and in big numbers. Why there are so many fish here is because it’s not fished, except maybe for somebody poaching.”

In the evenings, the ship’s crew worked on mapping areas of the seafloor with a multibeam sonar system, in which an array of 512 sound waves were beamed, each at a slightly different angle, from a transducer mounted on the hull. These sound waves traveled simultaneously through the water until they reached the seafloor, a shipwreck or other object that reflects sound.

Once the sound waves reached the object, they traveled back through the water column and were picked up by the receiver, which recorded the time it took. Then, the depth was calculated using a variety of factors.

The ship ran patterns, like mowing a lawn with a little overlap each time, to create a comprehensive bathymetric (depth) map. In conjunction with this, the ship also used a fisheries echosounder, which Donahue called a “fish finder on steroids,” to map the distribution of fish over a large area.

During the cruise, the Nancy Foster mapped 788 nautical miles of sea floor in the Dry Tortugas and in the Marquesas, an uninhabited island group about 20 miles west of Key West. This data will be analyzed, with special attention paid to what kind of structure tended to attract fish. The most interesting sea bottom found also was explored by the ROV.

“We will analyze the footage, to get estimates of the fish populations of the area we covered and then find a unit we can compare it to in other places,” said Alejandro Acosta, research administrator at FWC. “You don’t have boundaries, so we are dealing with individuals who are moving. We also don’t know if they are coming from very far or very close. It is just a snapshot.”

Many fishermen are skeptical of the science that is provided to justify no-take zones. Scientists are the first to say they don’t have all the answers and would love to do more field work, but limited resources prevent it. That’s one reason learning about the coral reef ecosystem has become a collaborative effort from a wide range of contributors: governmental agencies, academia, private conservationists and private users of the resources, including fishermen.

Even the ROV, owned by the National Marine Sanctuary Foundation and operated by the UNC Wilmington’s Undersea Vehicles Program, could only do so much. While it covered more territory than was possible by divers, it also was only able to document about three miles, a fraction of the area mapped. “But it’s still providing terabytes of invaluable information that can be studied by scientists from around the world,” Donahue said.

ROV pilots White and Lance Horn carefully drove the rig around and over coral structure, capturing 957 still images and nearly 15 hours of life on the sea floor.

After the ROV was back on the ship, small boats were launched to take divers back to the traps. They were still empty, so the divers rebaited them with squid. The next day, a scout team dove down to 105 feet and was relieved to discover a full trap: a black grouper, a scamp grouper and three margates, a type of tasty grunt.

The surgery team was deployed to tag the black grouper. “The trick is to get the fish to go into the net,” Barbera said. “We had to maneuver the net around some big margates, and then make sure the grouper didn’t shoot out of the hole when the net is not ready.”

The team got the grouper onto a V-shaped cradle, dorsal down, and measured it at 42 inches. Ariel Tobin, a biological scientist with FWC, performed the surgery by making a small incision about an inch long into its belly and then sliding into the opening a tag about the size of a AA battery. She closed the incision with three sutures. She also used a hypodermic needle to insert an external dart tag with FWC’s phone number.

The FWC scientists also install and maintain their acoustical receivers, which ping every time a tagged fish swims within its range (usually about 1,500 feet). It’s sort of like cellphone signals being picked up by cell towers. FWC currently has six, spaced along an approximately two-mile ridge at Riley’s Hump.

FWC tries to retrieve the information recorded on the receivers every six months to a year, although the receiver batteries can last about two years. For the fish tags, which cost about $350 each, the batteries can function for about three years.

Danielle Morley, assistant research scientist with FWC, picked up one of the receiver canisters that had been collected by divers, and before taking off the lid, she warned: “It will be smelly, like dead sea water.”

She uploaded the information to her laptop. That one station, which had been put in place June 2, listed 821 detections from three different tag numbers. The second station she uploaded listed more than 17,000 detections from 14 unique tag numbers.

It will take time to analyze the information from all six receivers. Many groups use the same system, which means her detections could include pings from another scientist’s tagged shark or sea turtle. FWC belongs to three networks that share information.

During the cruise, eight fish were tagged and five receivers formerly used in the Dry Tortugas were installed in the Marquesas, an area that allows fishing and has not been studied much. The scientists are interested to see how behavioral patterns of fish may differ in areas that are not protected.

“My favorite part is going down and looking at the fish before it’s tagged and wondering what it’s going to do in the next couple of years,” Morley said. “We take bets on how far it will go. Where do you think it will show up? What do you think it will do during the night? We’re so obsessed with what the fish will do.”







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