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.

Where, oh where, has my sea cucumber gone?

World Oceans Day, June 8, 2013

“Did you see any sea cucumbers?” I asked Ron as he struggled to get back aboard the inflatable tender.

“None”

“What about you, Wili?” I questioned.

He simply shook his head.

Day after day as we are being towed around the inner and outer reef systems of the Yasayasamoala Group of the Lau Islands, we are coming up with zeros on our data sheets. It’s disappointing work.

In the meantime, tin drying racks in the villages of Totoya and Matuku islands have been full of the critters. So far, Wili Saladrau, from Fiji Department of Fisheries, recorded over 700 individual sea cucumber (in the dried form called “bêche-de-mer”). This includes over 60 Holothuria fuscogilva (white teatfish) that can sell for over US$50 (FJ$100) a piece to specialty buyers in Fiji.

So are the local fishers just better at finding the sea cucumbers? Probably. If I was getting paid that much money per individual harvested, I’m sure that I would “get my eye in” much quicker in order to be able to spot them on the reef. But still, the densities of sea cucumber populations are running dangerously low.

Wili, Ron Vave of the University of the South Pacific, and I were asked by the Lau Provincial Office to do an assessment of the status of sea cucumber populations during the Living Oceans Foundation Fiji expedition throughout the Lau island group. Bêche-de-mer is a major source of income to coastal communities in Lau, but there is concern that the populations are on the precipice of collapse.

Serial depletion of sea cucumbers has occurred throughout the world to feed a growing middle class market in Asia, hungry for bêche-de-mer. While bêche-de-mer have been traded for at least 1000 years, the value of the catch has increased enormously over the past two to three decades as species are exploited and crash, thus becoming rarer commodities.

Sea cucumbers are long, tubular benthic echinoderms (in the same phylum as sea urchins) belonging to the class Holothuroidae. They were once found in most temperate and tropic benthic habitats worldwide, ranging from shallow intertidal areas to the deep sea. The majority of sea cucumbers move across the seafloor ingesting detritus and other reef gunk, thus cleaning the sediments and potentially reducing the spread of harmful algae. Because they can grow to be quite large, and many are conspicuously shaped and coloured, sea cucumbers are extremely vulnerable to fishing. In addition, population recovery is hampered by their slow growth rates and long time to reach maturity. Furthermore, when populations become too sparse and sea cucumbers cannot sense other individuals of the same species, they will fail to breed, resulting in local population collapse.

There is general lack of awareness of these population dynamics in Fiji. Although use of SCUBA for fishing is prohibited under the Fiji Fisheries Act, the Fiji Department of Fisheries has been issuing exemptions to traders. These middlemen supply local community members with gear and possibly some training if they are lucky – and then the race is on to catch the last of the sea cucumbers. Young men are diving 50, 60, 70, and sometimes over 80 m to find the remaining individuals from high value species. They are dying fairly regularly. Others are suffering debilitating side effects from the bends. I met one man during surveys in western Bua Province in November 2012 who was relegated to growing watermelons after becoming incapacitated from diving related injuries.

In Lau, most of the fishers are free diving, but apparently they are quite talented and can easily reach depths between 20-30 m. Most fishers that we have interviewed so far are happy with the status of the sea cucumber fishery as they are fetching high prices and the money covers household expenses, church contributions, and higher education fees for children, as well as offers the ability to purchase some luxury items. But few of the fishers seem aware that the good fortune may soon run out. What will happen then when there are few other options for earning income out in these remote islands?

There may be potential for populations to recover if management action is taken now. It likely will not be sufficient to set up locally managed marine areas with a few no-take areas. The sea cucumbers are already so widely dispersed that they may already be unable to reproduce. More active management may be required. This could entail finding wild caught individuals and placing them in close proximity to one another within pens in the no-take areas to encourage their reproduction and dispersal of their larvae into the open areas that everyone can access to fish. This strategy should optimally be coupled with minimum size limits so that people do not remove all of the young sea cucumbers before they reach maturity.

In honor of World Oceans Day, I ponder these issues in order to raise hope by coming up with creative solutions. Over the next few years, the Wildlife Conservation Society and other members of the Fiji Locally Managed Marine Area network aim to try out several different types of management with communities to see what works, what doesn’t work, and why. Ideally we want local communities to have a better understanding of sustainable extraction rates so that they will be able to maintain livelihood benefits into the future.

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Totoya times two

20130604_Totoya_SJupiter_06a_sm I’m having flashbacks. Two years ago on this very day, I was sitting on board a similar-sized yacht, anchored in the lagoon of Totoya Island in the Yasayasamoala Group of the Lau Islands. In June 2011, I was part of an expedition team from the Wildlife Conservation Society, Pacific Blue Foundation, Waitt Institute, Scripps Institute of Oceanography and Wetlands International-Oceania to survey Totoya’s Sacred Reef.[Editor’s note: See blog from the 2011 expedition at: http://newswatch.nationalgeographic.com/2011/06/08/expedition-to-the-sacred-reef-of-fiji-6/]

In honour of World Ocean’s Day, Roko Josefa Cinavilakeba, the high chief of the Yasayasamoala group, redeclared Totoya’s Daveta Tabu protected. In was indeed a great day for the communities of Totoya and those here to participate in the experience.

But time flies fast and furious in the Pacific. Flash forward two years and I’m back to Totoya again, this time on board the Khaled bin Sultan Living Oceans Foundation’s research vessel, the Golden Shadow. In 2008, I wrote a letter to the Foundation, inviting them to come to Fiji as part of their Global Expedition (http://www.sciencewithoutborders.org/science-without-borders/) to investigate the major threats and impacts to coral reefs around the world, with a view to providing data to help innovate new management solutions. It only took them five years to respond – and now, here we are, floating in the remote waters of Fiji’s Lau Province.

The Living Oceans Foundation brings a wealth of experience, knowledge and scientific tools to study coral reef systems, including the ability to map large sections of reefs which provides important information on natural resource inventories for management. When I approached other organizations in Fiji about where the Living Oceans Foundation should focus these efforts, almost unanimously people said Lau. The remoteness and limited options for transport to Lau makes it an unusually challenging place to conduct repeated surveys to assess changes in reef resources – unless you have access to a superyacht, that is.And thanks to Prince Khaled bin Sultan of the Kingdom of Saudia Arabia, we do.

I’ve suggested to the research team to resurvey locations on Totoya, Matuku and Kabara that were previously surveyed in the 1990s and 2000s by researchers from the University of Newcastle in England, as well as the sites that we surveyed inside and adjacent to Totoya Sacred Reef in 2011.

In the meantime, myself, Ron Vave of the University of the South Pacific, and Willie Saladrau of the Fiji Department of Fisheries are searching far and wide to assess the status of sea cucumbers in this region, which are being increasingly exploited for cash income by local communities. Sea cucumbers are easy targets – with limited mobility, they can’t get away from a keen freediver. And the perception is that they are just money sitting on the reef. In reality, sea cucumbers have an important ecosystem function to regulate the amount of nutrients in coral reef sediments, which likely keeps algal blooms under control (as I described in my blog on our surveys of Western Bua: http://wcsfiji.org.fj/coral-reef-resilience-surveys-in-western-bua/). So far, Willie, Ron and I have not had much luck finding the critters – but we are hopeful that some are still out there to sustain the livelihoods of the local communities.

Duty calls – time to get back in the water and then on to a meke session in Tovu village.

Moce mada.

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Can indicators predicting coral reef resilience be mapped from space?

In 2011, I participated in a workshop during the International Marine Conservation Congress in Victoria, Canada, where experts came together to discuss which were the most critical factors that affect the ability of coral reefs to resist and recover from climate disturbance. After much deliberation, our expert consensus produced a list with 11 top resilience indicators, based on their perceived importance, evidence base in the literature, and feasibility for managers to measure. The top indicators included:

–          Presence of resistant coral species

–          Historical temperature variability

–          Nutrient pollution;

–          Sedimentation;

–          Coral diversity;

–          Herbivore biomass;

–          Physical human impacts;

–          Coral disease;

–          Macroalgae;

–          Coral recruitment; and

–          Fishing pressure

We published a paper describing the selection of these indicators and how they might be used to prioritize sites for reef management in a changing climate.

However, during this process, I got to thinking. Site based measures of resilience indicators are nice, but they only allow us to say that one survey point is potentially better than any other survey point and leaves you with no information about all of the unsurveyed reef.

Wouldn’t it be even better, then, if we could combine the field data with satellite imagery to assess what are the main factors influencing the resilience indicators that we can derive from space? Then we could use those relationships to predictively map the resilience indicators over a broader spatial scale, such as across an entire fisheries management area (qoliqoli). This process would yield maps with relative values for every portion of the qoliqoli to enable us to make better decisions about how to plan marine protected areas (MPAs) and MPA networks.

We previously took this approach to predictively map characteristics of reef fish assemblages across the Kubulau qoliqoli in Vanua Levu, Fiji, and published the results in a paper in Remote Sensing. I went back to my co-authors from Simon Fraser University and the University of Queensland and asked, “Do you think we can take this same approach for mapping indicators of reef resilience?”

Our findings have just been published in a more recent issue of Remote Sensing, accessible here. We specifically focused on mapping resilience indicators for which data products were not already available. These included:

–          Stress-tolerant coral taxa, as a measure of resistance to coral bleaching;

–          Coral diversity, as a measure of resistance to bleaching and potentially past recovery potential;

–          Herbivorous fish biomass, as a measure of recovery potential due to the ability of herbivorous fishes to remove macroalgae from the reef, thus preventing harmful coral-algae interactions and allowing space for new corals to settle;

–          Herbivorous fish functional group richness, as a measure of recovery potential as fish remove algae in different ways (e.g. excavating, scraping, browsing) and it is necessary to have the full complement of types of herbivores to effectively remove most of the macroalgae;

–          Juvenile corals, as a measure of recovery potential from recent coral recruitment and survival; and

–          Cover of live coral and crustose coralline algae, as a measure of recovery potential both as a indicator of current coral-algal dynamics when coupled with the amount of macroalage, as well as a proxy for the amount of substrate available for coral settlement and source of new recruits.

We specifically used high resolution satellite data (<4 m pixels) to enable production of maps of resilience indicators at a scale meaningful for customary management systems in Fiji and the rest of the Western Pacific. We did not try to predictively map indicators which other people have successfully mapped (e.g. historical temperature variability, nutrients, sedimentation, physical impacts and macroalgae), but noted that our predictive maps could be combined with these data products within a spatial planning framework.

How well did we do? We were able to reasonably map relative differences in potential susceptibility to coral bleaching based on the composition of coral communities observed in the field. We were able to do this because some corals are more tolerant to environmental stress than others and they tend to be found in different environments and micro-habitats.

We also did a good job predicting distributions in the number of functional groups of herbivorous fish. This indicator likely also has strong environmental determinants as large excavators, such as bumphead parrotfish, steephead parrotfish and bicolor parrotfish, tend to be associated with forereef slopes and reef crests. We noted, though, that the total amount of “reef cleaning” performed by each group of herbivorous fish will be influenced by how many fish are present and their size. In addition, not all herbivorous fishes are created equal. A new, separate study from Fiji found that only 4 species of fish were responsible for eating 97% of the algae set out in a feeding experiment.

We did not do such a good job in predicting distributions of juvenile corals, but this was expected given that there are many factors that influence where corals may settle and how many survive. We also did not do very well in predicting coral diversity patterns. This was somewhat surprising given how much is already known about relationships between coral diversity and depth, exposure to waves and reef habitat. However, our results were likely influenced by errors in georeferencing and incomplete sampling across all of the habitat types in Kubulau qoliqoli. These issues could easily be improved upon in future studies.

What does this mean for reef managers? In the context of MPA planning, managers now have the potential to set targets for reef resilience indicators, in addition to habitat and feature representation, when designing MPA networks within decision support software (e.g. Marxan). This represents a considerable improvement over the current practice of designing or adapting MPAs based on site-based resilience score collected from relatively few sites across the planning region.

"Herbivores like this parrotfish help clean the reefs of algae. (c) Keith Ellenbogen" "New corals settling onto the reef surface help reefs recover from disturbance. (c) Keith Ellenbogen"

Coral reef resilience surveys in Western Bua

After only 2 weeks respite from our periodic harvest surveys in Kubulau, the Fiji  marine team has again packed up our kit and by planes, boats and automobiles made our way to the remote regions of western Bua Province. Given our success assisting the districts of Kubulau and Wainunu to develop and implement their ecosystem-based management plans, the Bua Provincial Office requested for WCS to replicate the model with the remaining districts in the  province. So we’re here to use our well-honed survey methodology to gain baseline data that will allow us to develop recommendations for marine protected area (MPA) network design. We’ll present the recommendations back to the communities during the first half of 2013 to ideally help local communities achieve their fisheries and livelihoods goals.
Marine Crew on the Adi Lase Bula

Our first destination was Navunievu village in Bua District. Natalie and I, as early arrivals, spent the afternoon drinking kava waiting for the others to arrive. The ladies on our team were assigned sleeping quarters on the floor in the village hall, which meant we were  constantly the centre of attention for eager children curious to check out photo slideshows and chatty ladies wanting to constantly peer at what we were doing. This made working, changing and sleeping challenging to say the least, and we jealously coveted the boys’ beds and privacy in their separate houses.

Our second challenge was the weather.  “E tau na uca veisiga i ke? (Does it rain everyday here?)” I asked just about anyone who would listen. They generally would just smile. Perhaps my Fijian accent is terrible or it is just a silly question—because, yes, of course it rains every day in Navunievu. This put a slight damper on our fieldwork when lunches of tinned tuna turned to tuna soup, and visibility at certain sites, particularly near the mangroves, turned to pea soup. However, despite the poor vis, we were pleased to note that the Bua District tabu (MPA), established nearly a year ago, was working well, with plenty of large food fish.

As if on cue, it began to pour as we departed Navunievu at the end of our first week, but the skies soon cleared and a rainbow halo rimmed the peaks of Yadua Island, our next destination. The smaller island adjacent to Yadua, Yadua Taba, is famous in Fiji as the home to Fiji’s endemic crested iguanas. The National Trust of Fiji has worked with the communities to establish a wildlife sanctuary on Yadua Taba for the approximately 20,000 iguanas living in one of the few remaining intact dry forests in Fiji. It is believed that the first iguanas rafted here across the Pacific from South America. Given that Yadua Taba is home to 90-95% of the crested iguanas in Fiji, the  species is highly vulnerable to threats from invasive alien species, such as rats, as well as habitat damage and climate change. Twenty thousand iguanas is quite a lot for a 70 ha island, so it didn’t take us long to spot them hanging out in the trees, munching on hibiscus leaves. Some were willing photo subjects—others were more feisty. I had two Jurassic Park moments when the lens of my camera was attacked  by some not-so-amused reptiles.

The community of Yadua village has also established a permanent, no-take tabu area on the reefs and other coastal habitats around Yadua Taba. However, our first impressions are that it may be subject to heavy poaching, given how quickly the fish flee from approaching divers. Unfortunately, these days in Fiji, given the weak legislation to support community-managed MPAs and lack of capacity for enforcement, once a tabu becomes well-known, it is like having a giant flashing beacon saying “FISH HERE!” It is no help that the latest draft of the Inshore Fisheries Decree has been put on hold indefinitely. I’m trying to stay positive that we can still empower the communities and provincial governments to work within the existing system and restrict fishing licenses.

The sea cucumber (or beche-de-mer) fishery requires the most urgent regulation. In general, Fijians do not eat most beche-de-mer. They are sold to middlemen for export to Hong Kong and on to the Chinese market. As single white teat may fetch over FJ$100, the perception is that they are just easy cash for the taking sitting on the reef. However, there are three big reasons why people should pay attention to the serial exploitation of species and regulate the fishery. First, sea cucumbers are the sweepers of the sea. They play important roles in nutrient cycling, which keeps algal blooms at bay. Secondly, with exemptions from the Fiji Department of Fisheries to collect beche-de-mer on SCUBA but improper training, divers are literally killing themselves by pushing depth limits to find valuable species as they become more and more rare. Lastly, the middlemen are taking most of the profits. If the communities were able to have more control, they could keep more of the benefits for themselves and control extraction rates so that they might always be able to “cash out” a haul in times of real need.

As it stands now in Yadua, there is a Korean middleman who has been operating from the next bay for over 20 years with the permission of the high chief of the area, who  does not live on the island. The community is unhappy, and the chief of Yadua has encouraged the young men to collect as many beche-de-mer as they can, thus forming a race to catch the last individuals. Currently the wealth is evident in the community, with generators, compressors, televisions and other appliances that we do not usually see in rural villages. However, I can only imagine the impending social issues that might be faced once the cash flow dries up when beche-de-mer populations collapse.

Another critical challenge facing Yadua is potential impacts of extreme weather from climate change. Water security is a serious issue on the island. Recently, a borehole was located to supply the village with water for drinking and cleaning, but it requires a diesel-powered generator to operate the pump. Just the other day, the community ran out of fuel for the generator, and the thought was to catch some of the wild goats on the island to sell for purchase of more fuel. They did indeed catch the goats, but with heavy winds, they were unable to take them across to Vanua Levu and no fuel could be bought. Meanwhile, the water levels continued to drop in the barrels and buckets.

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For our third week in the field, we moved over to Yaqaga Island in Lekutu District, also home to iguanas and, much to our pleasure, running water and flush toilets! The men of Yaqaga are also busy collecting beche-de-mer, which they sell to another middleman based in Galoa village. They have already seen declines in numbers on the surrounding reefs and are fishing less valuable species, like snakefish. Meanwhile, untrained divers are putting their lives at risk plunging to depths of over 80 m to find the remaining individuals. One diver, who recently suffered the bends, is now relegated to growing watermelons on the far side of the island. Unlike in Yadua, the people of Yaqaga and Galoa asked questions about what might be the impact of wholesale removal of beche-de-mer and what could be alternative sources of income for their children.

 

These communities also have another source of concern. Several years ago, the Fiji Government granted permission to a Chinese mining company to extract bauxite, used to make aluminium cans. The Chinese company was smart— in order to get their foot in the door in Fiji, they chose a small (<30 ha) site in pine plantation of limited conservation value and developed plans to export the ore back to China for the more ‘dirty’ processing steps. However, in the future, ore from other, larger claims may be processed in Fiji. In the meantime, communities say that they are  already feeling the impact of increased runoff of sediments from the Nawailevu mine and jetty. They say it has become harder to find Anadara clams (‘kaikoso’) and the waters have become increasingly silty.

Clearly there is much work to be done in this region and we are eager to help the communities both sensibly engage with the natural resource extraction industries, as well as develop management plans to balance their own needs for income generation with sustainable livelihoods. Stay tuned.