Ecovolontariat aux Fidji: Rapport mensuel
Conservation in Fiji - Monthly Update August - September 2014
Wow! What an amazing eight months it has been. If someone had told me that this project would have been so successful i would not have believed it! But here we are already been recognised as the “Best Shark Conservation project in the world” WWF. This accolade comes from the diversity of the project, with everything from collecting 50,000 plastic bottles to diving with 60 Bull sharks, from planting more than 20,000 mangroves to giving Puppet shows to kids, we do it all.
Not ones to sit back relax we are constantly making new partnerships and pushing forward. I look forward to coming to the project every day and seeing the excitement on the faces of the staff and volunteers.
“Be the change you want to see in the world” Gandhi
Well everybody related to this project certainly lives this quote.
Andy Hill, Project Manager
The shark surveys continue to produce exciting data. We have been adding more survey sites as well as continuing our Safe Diver training program for new divers. We have also added a more detailed before and after dive briefing to ensure that everybody knows what they are doing and is prepared to deal with emergencies should they arise.
The survey training dives that we do with the new divers helps them gain confidence, have better buoyancy control, be prepared for emergencies and be more aware about their environment and the team around them. This enables them to focus on the actual survey dive where we record sharks, rays, turtles and commercially important predatory fish species instead of being concerned about their diving skills.
We now have two marine reserves and associated control regions that we are surveying. The marine protected area in the South of Beqa Island has been fully implemented as a survey site and we continue to explore the region and find sites appropriate to conduct survey dives. This has been named the Medium Reserve and is around 5 km2. Next to this area we survey the control fishing area which is the same size called Medium Control.
Additionally are in the process of acquiring permission from three villages to survey and drop BRUVS in another marine protected area which will be our Small Reserve and Small Control region also situated in the South of Beqa Island. So far we have seen most of our sharks in the Yanuca marine protected area however we have been surveying this area the longest. We have observed the most rays (Bluespotted Ribbontail Rays and Spotted Eagle Rays) and Zebra sharks in the Medium Reserve.
We are excited to keep moving this project forward and support the BRUV research project.
Mangrove - Community Education and Awareness Project
We have built a new nursery at our new HQ capable of holding more than 3000 mangrove propagules for which we have planted more than 2300 propagules to date. Towards the end of this month we will be replanting the grown propagules from our planting partners’ mangrove nursery which are located at the Pacific Harbour Multi-Cultural School and Vunibau village. We (volunteers and staff) will be replanting these mangroves with the help of the students and the villagers mentioned above. The CEO of Coca Cola (South Pacific) will be meeting with us soon regarding our Recycling Project. We also have covered the province of Serua extensively with our Community education. Everyone is starting to recognize us and the important work we do here.
Juvenile Bull Shark Tagging Report
During the last 4 months the Juvenile Bull Shark Tagging Project has changed and moved forward in several ways.
The major accomplishment has been the Local Environmental Knowledge (LEK) survey of all villages adjacent to the Navua River from the river mouth to a distance over 16 km upstream (Fig.1). The volunteers made a total of 91 interviews to local fishermen from the different surveyed villages. Questionnaires were designed following the main concept from (Rasalato et al. 2009).
Basically, fishermen were asked the location and frequency of juvenile bull shark sightings/catches, season of such sightings/catches, distance from the River mouth, and time of day, among other important questions.
The general outcome from our LEK surveys suggest that juvenile bull sharks are generally found in the first 7 km from the River mouth upstream in the Navua River (Fig. 1). Another interesting result was that over 90% of the surveyed fishermen agreed on November and summer time to be the best season to see/catch juvenile bull sharks inside the Navua River. This season correlates with the parturition season for pregnant female bull sharks in Fijian Rivers (Rasalato et al. 2009; Brunnschweiler & Baensch 2011; Brunnschweiler & Barnett 2013).
In addition, during these last four months we conducted 48 fishing trips with a total of five juvenile bull sharks caught (Fig.2). An indirect measure of the relative abundance of a fishing resource is the Catch Per Unit of Effort (CPUE), which takes into account the number of sharks caught, the number of hooks used and the soaking time per set. Usually CPUE is measured as individuals catch per 1000 hooks hour. Our lines are currently 60 m long with a total of 28 hooks each. Therefore, our highest and lowest CPUE during these 4 months were:
Highest CPUE= (2 sharks / 3 hours x 56 hooks) x 1000 = 29,76 sharks per 1000 hooks hour
Lowest CPUE= (0 sharks / 4 hours x 56 hooks) x 1000 = 0 sharks per 1000 hooks hour
Our average CPUE was 1,11 sharks per 1000 hooks hour. This CPUE is low, although similar when compared to other studies with juvenile bull sharks in riverine systems during winter season (Simpfendorfer et al. 2005). So far three hypotheses come to our mind to explain the low abundance found so far.
The FIRST HYPOTHESIS comprises a migration out of the Navua that we do not know about and might explain the low abundance found. In fact, there are studies in different systems around the world that have found juvenile bull sharks in a wide range of area including areas of fresh water environments in different seasons (Simpfendorfer et al. 2005; Heupel & Simpfendorfer 2008; Ortega et al. 2009; Drymon et al. 2014).
The SECOND HYPOTHESIS involves the fact that there might be a lack of juvenile bull sharks due to a conservation issue. This might include anthropogenic impacts such as effects of dredging 11 km upstream from the River mouth on the entire ecosystem, habitat loss and pollution. Several previous studies in shark nursery areas have found detrimental consequences of these type of impacts in sharks’ nursery grounds (Gruber et al. 2001; Feldheim & Edren 2002; Gruber & Parks 2002; Jennings et al. 2008).
The THIRD HYPOTHESIS involves quick growth rates and therefore shorter times inside the nursery ground. This hypothesis although unlikely, has been proven in other species and systems (Dibattista et al. 2007). There has been hypothesized that juvenile sharks in nursery areas with high abundance of prey and high levels of predation risk grow bigger and faster, and therefore leave the nursery much faster, than sharks in protected shallow lagoons (Dibattista et al. 2007). During these four months we also had our first recapture. On April 28th we caught a 95 cm TL female and we did recapture her on the 14th of August being 111 cm TL. This suggests an extremely fast growth rate in only a few months which might be related to our third hypothesis.
Therefore, in the next months we have a specific plan of action to try to elucidate what is happening in the Navua River with the juvenile bull sharks (Supp. Material Table 1). We will keep conducting our normal fishing effort to compare our catching success in different seasons, since spring and summer are approaching. In addition, we will start experimenting with other fishing techniques such as gillnets to compare our catching success. Moreover, we will estart conducting a fishing survey to assess the density of prey items for juvenile bull sharks along the Navua River. This survey will help us estimate the best areas to catch the juvenile bull sharks since, as predators, they follow their prey. Finally, we will start with our acoustic tracking of juvenile bull sharks to learn more about the movements of captured individuals in the River as well as evaluating absence/presence data through active tracking.
August and September proved to be our most productive months thus far with the BRUV project. Biologically speaking, we observed shark species that were previously unseen by our BRUV camera. We recorded two tiger sharks, a juvenile silver tip, zebra shark. We also observed the more common grey reef, white tip and the occasional lemon and black tip! One of the most exciting videos of the month came with much anticipation when the staff dropped to retrieve the BRUV we found the bait cage torn to shreds 20 meters down current from where the BRUV was set.
When the staff and volunteers viewed the footage we found a large female grey reef and red snapper were taking turns ripping at the bait cage. The cage stayed intact for a while until the grey reef grabbed the bait cage, ripped it off the arm and shook it like an angry dog, all for our cameras to see. A photo is attached. What a sight it was! Even more exciting was the up-close encounter with the tiger shark in the Yanuca Marine Protected Area. The three meter juvenile female tiger interacted with our bait cage several times; bumping the bait cage, rubbing her nose on the bait arm and even giving the bait cage a test bite. Photo attached. These are the most exciting moments on the project, as tiger sharks are listed as Near Threatened on the IUCN Red List. We know there is a tiger shark population here that goes unseen by divers and fishermen because they typically stay away from divers and travel long distances across the ocean. Thanks to our BRUV’s they are being recorded for scientific data.
In July and August we managed to drop 27 BRUV’s despite the rough weather during the windy season here in Fiji. We had five BRUV drops cancelled due to foul weather conditions and therefore safety precautions. This Fiji winter-time also resulted in the chilliest water temperatures to date. The average temperature in early July was 27oC but dropped and stayed at a range between 24-26oC, compared to 28-30oC in the summer months. This could potentially affect the behavior or location of the sharks in the shallow waters of the lagoon versus the deep waters of the passage. A trend could prevail after more sampling after a few years of research.
It is still too early to make conclusions about our BRUV experiment because we need to drop 30 BRUV’s in each area of study, that will be a total of 180 BRUV drops with all three Regions of study; more about that later. At the moment, we have two regions (Large = Yanuca and Medium = South Beqa), each with a marine reserve or Marine Protected Area (MPA); this makes four areas of study. A reminder, we are testing the effectiveness of MPA’s and reserves versus traditional fishing areas (control area). We are also testing to see if the size of the reserves/MPA effects the conservation of shark, ray and indicator fish populations. At the end of August we had dropped 38 BRUV’s in total. We have dropped 12 BRUV’s in the Yanuca MPA and 10 in the Yanuca Control. This is our Large Region of study. Eight BRUV’s were dropped in the Medium Control and Reserve (Medium Region). The Medium Region of study was new to the project in June.
Looking forward to October, we have confirmed our third and final region of study. This will be our Small Region of study (~3.5km2). This gives us a total of six areas of study; three reserves/MPA’s and three control areas. This area is located on the southeast side of Beqa Island and the fishing rights belong to Dakulbeqa and Dakuni Villages of Beqa Island. The Small Region is near passages to the open ocean, the exterior of Beqa Lagoon’s barrier reef. Our hope is that the proximity to the deep water will bring more exciting action to the BRUV’s, meaning larger coastal/pelagic associated sharks such as Tiger Sharks, Hammerheads, Bull Sharks,, Silver Tips and even Spotted Eagle Rays and Manta Rays! Fingers crossed!
Other news in our BRUV world is our brand new BRUV! We now have a light-weight aluminum BRUV which makes transport as well as BRUV drops and ascents in-water much more manageable and safe for the volunteers and staff.
BRUV highlight video:
August Dirty Day saw Shark Conservation volunteers join the Bula festival which is the biggest festival in Fiji. We created a float to promote shark Conservation and had the great pleasure of transporting Miss Bula around for the day. All proceeds from the festival will go towards the charitable organisations in Nadi.
For Septembers Dirty Day we dedicated our time to clean up the Navua river. We tasked people with recording every piece of trash we picked up and the others kept count of each item as they cleared the river of trash. Some of the most common things picked up was plastic or glass bottles, diapers, food wrappers or appliances like T.V.’s and stereos. In some areas there was too much trash for to be cleared as the locals had dedicated these places as trash dumps on the side of the river. By the end of the day 4 boats had been filled with trash that was taken to the dump.
Part of our role as volunteers with Projects Abroad is to educate the community on the affect their actions have on their environment and in turn their sharks. By keeping the trash out of the river we are keeping the mangroves healthy. Mangroves are important to sharks because that’s where the pregnant females go to give birth. If there aren’t any mangroves then the baby sharks are more likely to die. Sharks have a low reproductive rate which means they only reproduce once every 2 or 3 years. They also take a long time to reach sexual maturity. If we aren’t giving them a chance, we are going to lose them which in turn destroy the surrounding ecosystem. When the community sees us picking up trash and caring for the river, we are showing them an alternative to the approach they have for trash disposal.
One of our many social events was the very entertaining Traditional Dance classes.
Volunteers dressed up in traditional costumes and learnt the art of the Filian Meke which is a dance that is used to protect the local fishermen from the dangers of the ocean and give them good luck and a fruitful harvest.