Dropping in for a fish census

Special to WCS by science writer, Amy West

Ready to deploy the BRUV off the support boat

Ready to deploy the BRUV off the support boat

A curious visit by a human or motored robotic vehicle likely sends deep-water fish fleeing. It’s difficult to accurately tally fish if we appear as an ungainly and potential predator. In addition, the robot’s electrical field and narrow camera view may not reflect the actual fish composition. So dropping video festooned with bait that sits patiently on the bottom can harmlessly capture which fish are out and about.

 

An Australian duo from Western Australia University aboard the Waitt Institute research vessel has dropped nearly 60 of these camera systems, fondly called  “BRUVs” (baited remote underwater video). Todd Bond and Jordan Goetze have perfected the art of heaving these awkward rebar frames into and out of the water with sheer brute strength, and, well, the help of a cleverly rigged PVC and wooden winch thanks to the Waitt Institute crew. Angling the pair of cameras also allows length measurements of the fish. Needless to say, these boy’s fish ID skills are top notch.

Winching made easier thanks to the Waitt Institute crew

Winching made easier thanks to the Waitt Institute crew

“Hey what is that fish?” I ask trying to describe the coloration.

Coris aygula,” says Jordan without missing one beat.

“And that one on the…,” I ask.

Heniochus  acuminatus,” he says before I can finish my sentence.  Later a fish shoots across the pixelated television screen, totally unrecognizable to all of us. “That’s an jobfish!” hollers out Todd.

 

 

Dropping these frames along Fiji’s reefs or seamounts gives us a peek into the fish assemblages at deeper depths; which are essentially unexplored. Luckily for us the reef system provides natural ledges. Reefs worldwide will typically level out at roughly 30 meters and 60 meters, and some at 90 meters etc… These natural platforms form from erosion thousands of years ago when sea level stabilized, allowing centuries of wave action to eat away at the coral. When sea level rises or falls, a reef is normally dynamic: either building up or dying off.

 

Finding a ledge after 60 meters was challenging-- it just drops off.

Finding a ledge after 60 meters was challenging– it just drops off.

When the team could locate these ledges on the sonar, they were ideal for their camera frames since most of the reef is so sheer. But the systems can go missing or slip off the line. Their recent loss of two cameras to the deep blue was hard to swallow, but par for the course when tossing expensive equipment overboard beyond our reach. Knots may come undone, and gear can be ripped away by currents or snagged on the way up.

 

 

 

Reviewing the footage back on board reveal fish fighting for bait, groupers stopping in for a mouth cleaning at cleaner stations, and a black blotch emperor at ~50 m losing its colors when near the bait. The sea bream at 70 meters changed its colors and striped pattern, too. If they didn’t capture this metamorphosis on video, it could be challenging to identify these fish from a still image without their markings. On this trip the duo have seen more cod and emperor fish at 70 to 80 meters, which have been largely fished from the shallower depths. They’ve also seen fish that extend well beyond their range as noted in fish ID guides.

 

Checking to make sure the cameras stayed on and what fish they captured

Checking to make sure the cameras stayed on and what fish they captured

Recently Jordan and WCS used this video technique to conclude whether the marine protected area had an effect on sharks. These baited cameras inside and outside of Fiji’s largest protected area, Namena Marine Reserve, showed twice as many sharks in the shallow waters of the reserve. Their numbers are thought to be higher inside the safe zone because of the larger number of prey fish available to them.

 

 

Surprisingly it’s the selective practice of spearfishing that’s taken a toll on Fiji’s reefs. It’s too craggy and steep to cast nets on the offshore barrier reefs, but with the expanding market for fish, more poaching, more spearfishing at night, and more boats carrying spearfishers occurs. There’s hope though: fish may be more intelligent than we think. The idea of “deepwater refuges” is a relatively new concept, but an old simple observation made by many divers: more fish are seen below the limits of where they are fished. The BRUVs finally quantified that observation. By dropping cameras both inside and outside an established and newer marine reserve at five meters and 30 meters, scientists found that fish targeted by fishing were missing in the shallower areas, yet seen deeper. The types of fish found deeper were similar within and outside the two marine reserves, indicating depth can be a natural refuge.

 

Though these one-hour videos give just a glimpse into a tiny cross section of the ocean, over time the data can show trends to help manage marine life that are beyond our view.  It keeps the fish counters safe and dry, which the boys aren’t ecstatic about, but they know sacrificing underwater time means collecting more data. All they need to do is grab a cup of coffee and start shouting out fish names.

 

Amy West has traveled worldwide as a marine scientist, specializing in fisheries and deep-sea ecology. Now as a science communicator she brings stories about ocean realms to the public through radio, video, photography, and writing. She’s usually diving into adventurous stories that take her on or below the water.

Mutiny on the Reef

Special to WCS by science writer, Amy West

Mt. Mutiny looms up from the sea bottom. Photo by Amy West

Mt. Mutiny looms up from the sea bottom.
Photo by Amy West

After the mutineers left Captain William Bligh to steer his own course, Bligh probably didn’t realize he’d passed so close to an astonishing seamount rising nearly straight up from the seafloor. Of course how could he, when cannibals were most likely chasing him from Fiji? In recognition of his plight, this popular dive spot has been christened Mt. Mutiny.

Plowing through calm waters between the two large islands of Fiji – Vanua Levu and Vitu Levu – where it feels like open ocean, “land” abruptly stops you in your wake: the seamount’s peak is visible at the surface. During low tide, you could theoretically walk on it.  Just a few hundred feet off its edge, the depth reaches down to 600 meters—a sheer drop.

Seamounts are usually rife with life. These undersea mountains are prime features for currents to swoop around and carry food to the diverse filter feeders such as corals and sponges. The stony and soft assemblages in turn attract an entire ecosystem of marine life that rivals most regions of the ocean. These volcanic structures can be uplifted mountains that are unhurriedly inching their way to the surface, such as the emerging island Lo’ihi in the Hawaiian Islands. Or they could be islands that have slowly eroded and sank like northern Hawaii’s Meiji seamount. We don’t know the history of Mt. Mutiny without drilling into it, but one thing is clear– it does not seem to be teeming with life. Many of the larger fish and top predators seemed to be out to lunch, or perhaps more likely, became lunch.

Stacy watches the ROV footage. Photo by Amy West

Stacy watches the ROV footage.
Photo by Amy West

Seamounts are hotspots for fish, which is why fisherman love them- the suspected reason that they are missing. With support from the Waitt Foundation and Institute to help create offshore-protected areas, the first item on the agenda was to document marine life below diver depths. The Institute’s contribution of their research vessel and camera-equipped robot allowed us a quick glimpse. This steep mountain had seemingly discrete bands of life: reef-building corals for about 30 meters, then softer corals below it, and different species like larger sea fans and encrusting algae and sponges below it. After 60 meters the seamount appeared more barren and so vertical that tracks of rubble flows were noticeable- as if someone had driven an ATV up its side.

Coral rubble flow down the seamount.  Photo by Amy West

Coral rubble flow down the seamount. Photo by Amy West

An astonishing amount of ambient light was still apparent at 150 meters, but not a lot of fish. Whether it was due to the loud, whirring vehicle or our limited field of view, dives near the surface also appeared devoid of large and abundant fish. Interestingly though, at 180 meters we found banner fish amongst saddleback snapper. One references notes a banner fish’s range to only 75 meters.

Additional dives will give us a better snapshot of the diversity. Yet, whatever this seamount’s patterns, bringing Fijis’ deeper underwater seascape to the surface is imperative. The release of oil exploration licenses around these islands calls for urgency to discover what might need protected before it could be destroyed.

Dr. Don Potts and Dr. Stacy Jupiter in Fiji

Dr. Don Potts and Dr. Stacy Jupiter in Fiji

On board the Waitt Institute research vessel, we are fortunate to have coral spotting guru, Dr. Don Potts from UCSC, as well his former PhD student, Dr. Stacy Jupiter, who has been WCS Fiji’s program director for the past five years. WCS’s Sea and Sky director Claudio Campagna, who specializes in the creation of Argentina’s pelagic marine protected areas, also aids in the conservation goals of this research leg.

Click on the link below to see exciting video footage from the ROV: Fiji seamount survey video

 

Amy West has traveled worldwide as a marine scientist, specializing in fisheries and deep-sea ecology. Now as a science communicator she brings stories about ocean realms to the public through radio, video, photography, and writing. She’s usually diving into adventurous stories that take her on or below the water.

Urgent protection needed for Vatu-i-Ra Island Sanctuary

Red-footed booby chick peering down from the remaining canopy

Red-footed booby chick peering down from the remaining canopy

Today was the first time that I stepped on Vatu-i-Ra Island in almost a year and a half. Right away, I knew things looked different.

“Why is there so much light streaming through the canopy?” I wondered.

And then I saw the branches and trunks of felled trees all around. Damage from Tropical Cyclone Evan? Possibly a little bit, but our hosts seemed to think that people were cutting trees to build fires for camping.

 

 

The small (2.3 ha) Vatu-i-Ra Island, located off of Ra Province, is a critically important seabird site, home to a large breeding colony of black noddies (Anous minutus), as well as dense populations of red-footed boobies (Sula sula) and lesser frigatebirds (Fregata ariel), breeding hawkesbill turtles (Eretmochelys imbricata) and the endemic pygmy snake-eyed skink (Cryptoblecephalus eximius). Due to these features, BirdLife International declared the site an Important Bird Area.

Vatu-i-Ra Island is particularly special because of an enormously successful project by BirdLife International, NatureFiji-MareqetiViti, the Pacific Invasives Initiative, the Pacific Invasives Learning Network and the New Zealand Department of Conservation to eradicate invasive rats (Rattus exulans), which were having a negative impact on bird populations. The island was declared rat free in 2008 and the bird populations have boomed. Ever since, Sione Gonewai, leader of the traditional landowners from the Yavusa Nagilogilo, has been working courageously to try to get Fiji Government to protect this critically important bird breeding ground.

But now I saw their breeding habitat in tatters. There were dead birds in the trees and on the ground. Moreover, a boat of fishers pulled ashore and started building a fire with the dead branches.

“Have you been fishing?” I asked.

They replied yes. They had come from Tailevu and worked as a crew to sell fish to a middleman based in Rakiraki, who then vends his haul at Nausori market.

“Did you know that this area is protected?” I further questioned.

They claimed no. It is somewhat understandable, given that the communities only declared the island and the northern half of Vatu-i-Ra Reef tabu in March 2012 and the protected status has been little publicized. Sione was not happy, but he agreed to let them off without penalty if they consented to be interviewed for a documentary we are making to highlight the need for increased management across the Vatu-i-Ra Seascape.

Today’s encounters highlighted to me just how urgently this protection is needed. It appeared as if perhaps a quarter of the trees have already been lost. And it would not take much for an errant match to ignite all of the dry brush that has accumulated and burn down the remaining habitat.

“Do you like the birds?” I asked the fishermen.

“Yes,” they replied. “Where there are sea birds, there are fish.”

I hope that through our efforts and assistance we can help hasten the protection of this critical bird sanctuary and ensure the adjacent reefs are managed both to support the breeding populations of birds and the fishermen from all across Fiji who depend on fish for their livelihoods.

We will soon be kicking off a campaign to protect the biodiversity and livelihoods of people and ecosystems across the Vatu-i-Ra Seascape. This project is being supported by the Waitt Foundation and the John D. and Catherine T. MacArthur Foundation. Stay tuned for more information to come.

Felled trunk and branches in the centre of Vatu-i-Ra Island

Felled trunk and branches in the centre of Vatu-i-Ra Island

A fishing boat from Tailevu pulls ashore

A fishing boat from Tailevu pulls ashore

A white-tailed tropicbird (Phaethon lepturus) at the top of the island

A white-tailed tropicbird (Phaethon lepturus) at the top of the island