Preliminary assessment of mud crab stocks in Bua Province

By Yashika Nand

Mud crabs are a popular dish in Fiji that over the years has become a luxury food item. Single large mud crabs will cost you FJ$50-70 per crab or FJ$100-150 for strings of crabs at the Suva market, with the larger ones selling out very quickly. Mud crab dishes can cost you FJ$40-50 per dish.

A woman mud crab fisher. Credit:WCS

A woman mud crab fisher. Credit:WCS

There is a general perception that stocks around Viti Levu have been depleted while those in Vanua Levu are still healthy. However, we don’t have any data to verify this perception. We also do not know if we are harvesting too many female crabs with eggs or too many undersized crabs. How many crabs do we need in a mangrove forest to enable the local population to continue and thrive? These were some of the questions the Wildlife Conservation Society (WCS) are fishing for answers for

In July 2016, WCS partnered with the female representative for the Fiji Locally Managed Marine Area (FLMMA) network, Department of Fisheries and women mud crab fishers to trial a method to determine the density and biomass (or weight) of mud crabs in different mangrove forests in Bua Province. Our early discussions with these fishers taught us that mud crabs inhabit three major habitat types – mangrove systems, intertidal mudflats, and coral reef systems.

After discussion with a number of international experts, we decided to trial a survey technique that combines a “depletion method” with “transect surveys”. Basically, very experienced mud crab fishers were asked to collect all the crabs they can find within a fixed and marked area (square) 400m2 in size. Each crab that is caught is tied and at the end of the survey measured to get the carapace (shell) length and total length, weighed and then released back into the mangroves or in some cases, kept for sale or consumption.

WCS Conservation Scientist, Margaret Fox. Credit:WCS Fiji.

WCS Conservation Scientist, Margaret Fox. Credit:WCS Fiji.

We conducted mud crab surveys in the districts of Dama, Navakasiga and Lekutu. We took a selected our sites based on the following criteria: (i) fishing pressure; (ii) density of mangrove systems; and (iii) types of mangrove forest. What we did not anticipate was how intensive it is to conduct surveys in Rhizophora forests, which are known for their complex array of aerial roots. It took us almost 45 minutes to mark the boundaries of one quadrat, especially for us town dwellers who are not used to walking through mangrove forests.

Over 7 days, we surveyed 30, 800m2 of coastal mangrove forests and developed a deep appreciation for the hard work that goes into catching mud crabs, and the skills required to find the crabs. The women we worked with walk barefoot through mangrove forests, looking for crab holes, which scattered in no real pattern.

We learnt that mud crab fishers spend hours in a mangrove forest looking for crabs that we enjoy eating, most only catching 2-10 on the low tide. Our preliminary analyses suggest that mangrove forests are a habitat for majority adult and some juvenile and sub-adults. The densities we recorded in Bua Province were slightly lower than that those that have been documented in New Caledonia and Australia. However, we were tide constrained and the challenging habitats we had to survey and scattered distribution of mud crabs meant we might have slightly underestimated the population status. However, the surveys conducted are a good baseline for understanding the status of the stocks and the fishery, especially if we link it to catch rates and volumes by local fishers. And most importantly, the surveys allow us to engage directly with mud crab fishers to help them assess the stocks in their mangrove forests.

Understanding what state the stocks are in, is a good first step to understanding what management measures need to be in place to ensure the fishery is sustainable for the long-term, and Fijians can keep eating the mud crabs they love!

Towards greener taxes and subsidies in the Pacific Island Countries and Territories

Towards greener taxes and subsidies in the Pacific Island Countries and Territories

By Sangeeta Mangubhai

Aichi Target 3 under the Convention on Biological Diversity states that “by 2020, at the latest, incentives, including subsidies, harmful to biodiversity are eliminated, phased out or reformed in order to minimize or avoid negative impacts, and positive incentives for the conservation and sustainable use of biodiversity are developed and applied, consistent and in harmony with the Convention and other relevant international obligations, taking into account national socio economic conditions.”

Women sellers in Suva market. Credit:WCS Fiji

Women sellers in the Suva market. Credit:WCS Fiji

Under the RESCCUE project (www.spc.int/resccue) being funded by the French Development Agency (AFD) and the French Global Environment facility (FFEM) and implemented by the Pacific Community (SPC), a review is being done to look at what harmful subsidies and fiscal policies are in place in Pacific Island Countries and Territories in various economic sectors. These sectors include mining, fisheries, agriculture, transport, waste management, urban development and tourism. This work aims to tie taxation and subsidies to sustainable development goals, particularly around biodiversity and ecosystems under a coastal integrated management framework.

Taxes and subsidies if applied incorrectly can lead to increase resource use, increase in emissions and natural resource degradation, which can quickly become large problems for small island developing states. This is largely because taxes and subsidies are often not proportional to environmental impacts.

As a Pacific Islander, I want to see my country develop, but not if the cost is the loss of our rich biodiversity and our quality of life. I don’t want to live in a Fiji without its endemic birds and iguanas, traditional plants and medicine and wild places like the Vatu-i-Ra Seascape. I am proud that Fiji has a National Green Growth Framework, but I worry that this framework makes little reference to the removal of perverse taxes and subsidies.

Nabouwalu Jetty in Vanua Levu. Credit: WCS Fiji.

Nabouwalu Jetty in Vanua Levu. Credit: WCS Fiji.

At the IUCN World Conservation Congress I learnt that if correctly applied, taxes and subsidies can help reduce extraction, improve quality of water and soil and provide financing to support environmental objectives. Examples of greener taxes and subsidies include quotas on fisheries, taxes on harmful substances like pesticides, waste generation, and water pricing. As a partner on the RESCCUE project the Wildlife Conservation Society (WCS) looks forward to supporting the Fiji government find greener tax and subsidy incentives to contribute to the goals of the National Green Growth Framework.

How well did Fiji’s coral reefs survive Tropical Cyclone Winston?

BY: Sangeeta Mangubhai

After 10 days at sea, travelling over 500km and completing 26 dives, I have solid data on the scale and intensity of damage to the Vatu-i-Ra Seascape, from Tropical Cyclone Winston that passed through Fiji on the 20 February 2016. Coupled with cyclone damage, I assessed coral diversity and coral bleaching patterns throughout the seascape, on fringing reefs, bommies, underwater pinnacles and reef channels.

Sangeeta on board NAI'A exploring the damage to Fiji’s coral reefs following Cyclone Winston

Sangeeta on board NAI’A exploring the damage to Fiji’s coral reefs following Cyclone Winston

Damage to coral reefs was highest in the north, and lowest in the south, which as expected, followed the pathway Cyclone Winston took through Fiji. It was clear that where the eye of the cyclone passed, corals sustained damage. However, the level of destruction was highly variable and patchy between reefs.

There really was not easy way to predict which reefs would be damaged and which ones would remain unscathed – both windward and leeward reefs equally sustained damage.

Sadly Fiji experienced significant losses of sea fans (gorgonian corals) and soft corals at almost all of the sites. Table and staghorn Acropora (branching) corals were broken off at the stems, often sitting upside down on the substrate or obliterated into small pieces. You still see flashes of colour from sea fans and soft corals, but now you have to look a little harder to find them. Sides of fringing reefs, bommies and pinnacles had large scoured out areas, with clean white surfaces or covered in a fine layer of turf algae. Large volumes of old and new rubble accumulated in between reef structures, shifting around with the currents. The Nasi Yalodina, a shipwreck sitting at 30m in the eastern Bligh waters had been pushed down to deeper depths and was no longer visible to divers.

In addition to sustaining mechanical damage from the cyclone, the reefs had coral bleaching (ranging from 0-20%), caused by thermal stress from the El Nino cycle we are in. Post-cyclone, the temperature has dropped a couple of degrees and now rangeds from 27-28°C, which if continues, will help corals return to normal. Thankfully, the fish, shark and manta life were flourishing. We dived and snorkelled with 10 mantas across the Vatu-i-Ra Seascape, and large schools of barracuda, big-eye trevally, fusiliers, surgeonfish, and colourful anthias.

Bleached-Acropora-coral-continues-to-provide-a-home-for-blue-chromis-fish

Bleached-Acropora-coral-continues-to-provide-a-home-for-blue-chromis-fish

So what next for Fiji’s reefs? Well, the road to recovery will depend on how well corals successfully reproduce and their larvae settle onto reefs. Some species like Pocilloporids (which provide shelter for fish and other cryptic invertebrates like crabs and shrimps), usually spawn multiple times, releasing fully formed larvae into the water column that are ready to settle immediately onto reefs. Other hermaphroditic species like branching Acroporids, will release eggs and sperm into water column and fertilised eggs will develop into larvae, before settling onto reefs. We know so little about the timing of spawning in Fiji, and what factors result in good pulses of recruitment onto reefs.

Large bleached 3m diameter Porites Coral

Large bleached 3m diameter Porites Coral

My concern is that corals that are under bleaching stress, will invest their energy in staying alive, and will forfeit reproduction for up to 12 months. If this happens, the recovery of Fiji’s reefs might be slow or delayed. This is the first time I am aware of, where our reefs have to deal with both climate-induced bleaching stress and the mechanical damage from a cyclone.

It is going to be even more important over the next 12 months and longer for us to look after our coral reefs in Fiji, to give them the best fighting chance of recovery. Instead of seeing them as infinite resources for us to use without limit, we should see them like our gardens and plantations, needing care and maintenance to ensure they are grow and are healthy, and can continue to sustain us.

 

Assessing the Namena Marine Reserve off Vanua Levu

BY: Sangeeta Mangubhai

Over the last two days we have been diving in the Namena Marine Reserve. There was much debate before we got here whether Nai’a Cruises should venture up to the reserve, as there were reports of large scale damage both to the land, coastal villages and adjacent coral reefs. The marine reserve in particularly, juts out like a finger from the main island of Vanua Levu and the eye of the storm passed over it.

Vibrant-coloured-soft-corals-in-the-Namena-Marine-Reserve

Vibrant-coloured-soft-corals-in-the-Namena-Marine-Reserve

Namena is special because it is the largest no-take marine reserve in Fiji, and Nai’a Cruises has been diving these reefs for decades, promoting its conservation alongside the Wildlife Conservation Society (WCS) and the Coral Alliance. Thousands of divers from all over the world have visited these iconic reefs. Countless photos are captured of the marine life in the reserve, and numerous inspirational articles appear in dive magazines about Namena’s rich and diverse fish, invertebrate and coral communities.

Namena is part of the Kubulau District where WCS has worked for more than a decade supporting local communities on natural resource management. The communities have a management plan that outlines how they manage their resources from the mountains all the way down to the reefs. The people of Kubulau have inspired other districts in Bua province to develop their own district ‘ridge to reef’ management plans.

 Sangeeta-Mangubhai-surveying-reefs-for-cyclone-damage-and-coral-bleaching

Sangeeta-Mangubhai-surveying-reefs-for-cyclone-damage-and-coral-bleaching

What was firstly evident on arriving at the Namena Marine Reserve was that Tropical Cyclone Winston had decimated Namena Island and the small eco-resort there. The island once lush with island forest, supporting a massive population of seabirds, was now barren, devoid of any green foliage. Trees were bent over, twisted and uprooted by the 185 mph winds. Only a handful of masked boobies (an iconic seabird) sat on bare tree branches, exposed and baking in the sun. We visited the island and spoke to some of the resort staff trying to clean up the island and salvage any remaining materials they could. Their families are thankfully all safe, but every building has been destroyed including their dive center and their jetty.

Under the water, the reefs in the marine reserve have done better than Namena Island. The cyclone has left a somewhat patchy trail of destruction. Some reefs we dived on were badly damaged with sea fans, soft corals and delicate branching corals the hardest hit. Some sea fans were ripped out by the roots, while others that were 2-3 meters across have been shredded in half. There were areas where large volumes of old and new rubble accumulated in between the reef structures and are shifting around with the currents (bad!), and other areas where the rubble was cleared away and swept to deeper waters (good!), leaving clear bare substrate ready for new coral recruits to colonise. Some areas the force of the waves had ripped off large massive corals and boulders.

 Healthy-reefs-in-Namena-Marine-rserve-that-were-untouched-by-cyclone-Winston

Healthy-reefs-in-Namena-Marine-rserve-that-were-untouched-by-cyclone-Winston

Despite the damage, there was a lot of evidence of the resilience of the Namena Marine Reserve that gave me hope. There were clear areas of reef that seemed largely untouched by the cyclone. Sites popular with tourists like the ‘Two Thumbs Up’ and ‘Kansas’ were for most part intact, and continued to flourish all the way from the base of pinnacles to just below the water surface. It is almost impossible to predict which reefs survived the cyclone, and which ones sustained serious damage. There is no clear pattern so far. We would dive on one reef to find it broken apart by waves, turn a corner and find a reef intact and flourishing. The fish and shark life seemed to be at this stage, largely unaffected. We were lucky to swim with white tip and grey reef sharks, large manta rays and big schools of big-eyed trevally, surgeonfish, and fusiliers. Well-protected marine reserves like Namena have both a great chance of recovery, and will play an important role reseeding adjacent ‘less protected’ or ‘less managed’ reefs. For the community of Kubulau, the the Namena Marine Reserve is not only a biodiversity asset they can share with divers that visit Fiji, but also an insurance policy to ensure they always have healthy fisheries.

 

Coral bleaching in the Vatu-i-Ra Seascape – how bad is it?

BY: Sangeeta Mangubhai

Bleached Anemone

Bleached Anemone

Before Cyclone Winston hit Fiji, we were following closely the El Niño cycle, the drought and reports of coral bleaching from dive operators. The local newspaper, the Fiji Times, ran a number of stories about fish kills and there was a lot of speculation about whether this was caused by the elevated sea surface temperatures we were experiencing across Fiji. Temperatures on inner reef flats along the Coral Coast recorded temperatures as high as 35°C. A similar story emerged from Vanuatu. http://www.huffingtonpost.com/lagipoiva-cherelle-jackson/fish-kills-reported-in-fiji_b_9233612.html

I have been spending part of each dive collecting data on the scale and intensity of bleaching across a range of habitats including fringing patch and lagoonal reefs, channels and bommies, using a rapid assessment technique developed by Dr. Tim McClanahan and Dr. Emily Darling from the Wildlife Conservation Society.

Over the last four days, I have documented mild levels of bleaching, with common coral genera like Acropora, Pocillopora, Porites (massive forms), Montipora and Pavona mostly affected. By mild, I mean that corals are either iridescent or slightly pale, rather than fully white (i.e. bleached). The tissue on these corals is still very much alive. A few very large colonies of Porites and Pavona are severely bleached in the shallow lagoon at Gau Island, but again still alive.

For most part the bleaching is patchy and affecting corals living at 5-15m depth. Water temperatures in the Vatu-i-Ra Seascape have dropped by about 2°C since the cyclone to 27°C. If these cooler water conditions continue, we can expect that most pale or bleached coral colonies will return to normal over the upcoming weeks.

It is going to be even more important that we look after our reef resources over the next 12 months, to give our reefs the best chance of recovery, so that they can continue to feed and sustain us here in Fiji. How well we care for our reefs will determine how well they recovery from both climate-induced temperature stress and the mechanical damage caused by cyclone Winston.