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FIJI MARINE CONSERVATION & DIVING
PROGRAMME
Beqa Island, Fiji
FJM Phase 171 Science Report
1st January2017 – 31
st March 2017
Teodora Forascu & Kimberley Lees M.Sc.
Staff Members
Jessica Betts (JB)
Kimberley Lees (KL)
Teodora Forascu (TF)
Claire Collins (CC)
Project Coordinator
Research Officer / Dive Officer
Research Officer
Assistant Research Officer
Table of Contents 1. General Introduction ....................................................................................................................................... 3
1.1 Frontier ......................................................................................................................................................... 3
1.2 Location ........................................................................................................................................................ 3
1.3 Background ................................................................................................................................................... 5
1.3.1 Natural Sources of Reef Degradation ............................................................................................ 5
1.3.2 Anthropogenic Sources of Reef Degradation ................................................................................ 6
1.4 Project Aims & Objectives..................................................................................................................... 7
2. Training ............................................................................................................................................................... 8
2.1 Briefing sessions ............................................................................................................................................ 8
2.2 Science lectures ............................................................................................................................................. 8
2.3 Field work training ....................................................................................................................................... 9
2.4 BTEC and Other Qualifications .................................................................................................................... 9
3. Research Projects .............................................................................................................................................. 10
3.1 Baseline Survey of Coral Reef Health in Beqa Lagoon .............................................................................. 10
3.1.1. Introduction ....................................................................................................................................... 10
3.1.2 Survey Areas ....................................................................................................................................... 11
3.1.3 Materials and Methods ...................................................................................................................... 12
3.1.4 Results ................................................................................................................................................. 13
3.1.5 Discussion ............................................................................................................................................ 18
3.2 Mangrove Mapping in Vaga Bay ................................................................................................................ 20
3.2.1. Introduction ....................................................................................................................................... 20
3.2.2 Restoration Area ................................................................................................................................ 21
3.2.3. Materials and Method ....................................................................................................................... 24
3.2.4. Results ................................................................................................................................................ 24
3.2.5 Discussion ............................................................................................................................................ 25
3.3. Identifying Blacktip Reef Shark Nursery Grounds ..................................................................................... 26
3.3.1. Introduction ....................................................................................................................................... 26
3.3.2. Methodology ...................................................................................................................................... 28
3.3.3. Results ................................................................................................................................................. 29
3.3.4. Discussion ........................................................................................................................................... 29
4.0 References .............................................................................................................................................. 31
4. Acknowledgement ............................................................................................................................................. 37
1. General Introduction
1.1 Frontier
Frontier, established in 1989, is a UK-based non-profit NGO. Its mission statement is:
“to conserve the world’s most endangered wildlife and threatened habitats and to build
sustainable livelihoods for marginalised and under resourced communities in the world’s
poorest countries and to create solutions that are apolitical, forward-thinking, community-
driven and innovative, and which take into consideration the long-term needs of low income
communities”.
Frontier employs non-specialist volunteers, or Research Assistants (RA). Frontier’s marine
projects give RAs basic science and species identification training at the beginning of their
placement, to enable them to collect data on local fish, benthic and invertebrate species. After
working on Gau Island in Fiji conducting baseline surveys, Frontier relocated to Beqa Island,
south of mainland Fiji, in order to assess the status of the coral reef systems around Beqa and
within Beqa Lagoon.
1.2 Location
Fiji is an archipelago in the South Pacific Ocean composed of 332 islands and 500 islets and
cays, with land mass occupying 18,376 km² (Cumming et al.,, 2002) (Figure 1).
Approximately one third of the islands are inhabited and, of these, the two largest islands, Viti
Levu and Vanua Levu, contain approximately 90% of Fiji’s population (Vuki et al.,, 2000).
Figure 1: The Fiji Islands, Beqa circled in red (adapted from Veitayaki, 2006).
Beqa is a large island in the Fijian archipelago and lies within Beqa Lagoon (Figure 2), with
the coordinates 18°24’S 178°08’E. The island is located approximately 10 km south of the
main island of Viti Levu and has a population of around 3,000 people. Nine villages are
present on Beqa. These are Waisomo, Lalati, Soliyaga, Dakuni, Dakuibeqa, Naceva,
Naiseuseu, Rukua and Raviravi.
Figure 2: Beqa Island with surrounding barrier reef system (Google Earth)
Fiji is world renowned as the Soft Coral Capital of the World and is also home to Beqa
Lagoon, which is famous amongst divers. It features over 50 world class dive sites and is
frequented by numerous species of mega fauna, including dolphins, whales, sharks, rays and
turtles. The primary source of income on Beqa is tourism, largely through recreational scuba
diving. No large scale fishing, agriculture or horticulture occurs and heavy industry is non-
existent, therefore the reefs within Beqa Lagoon are unaffected by the potential negative
environmental impacts that such industries can bring (FLMMA, 2013).
Fiji's coral reef fisheries are mainly inshore, small-scale subsistence and artisanal fisheries and
are therefore recognised as not receiving the management attention at a national level. The
total value of Fiji's subsistence and artisanal fisheries was US$64million (FAO 2007). Of Fiji's
400 traditional fishing grounds (qoliqoli), around 70 are over-expolited while 250 are fully
developed (Teh et al.,, 2008). Various no-take or ‘tabu’ areas have been designated by chiefs
of the villages to try to control extraction levels as village population’s increase. The ‘tabu’
areas surrounding Beqa can be seen in figure 3. Although village chiefs have no legal right to
the reefs, they traditionally lay claim to certain reefs within their territories and consequently
have the power to create ‘tabu’ areas on reefs of their choice in order to maintain populations
of targeted fish species for subsistence. This unofficial law is expected to be respected and
adhered to by all inhabitants of Beqa Island. Studies on other reefs elsewhere have shown that
similar traditional methods are an effective way to control and sustainably manage harvest
rates of marine resources (Hoffmann 2002).
N
Figure 3: Tabu areas around Beqa (FLMMA, 2013).
1.3 Background
Fiji is dependent on its low lying coastal regions for its socio-economic development (Teh et
al., 2008). This, like many other South Pacific islands, makes it extremely vulnerable to
climate change. Current predictions indicate a potential rise in global sea levels of between
49.9cm to 1m by 2100 (Solomon et al., 2009). The frequency of destructive environmental
events is predicted to increase, occurring at a faster rate than potential recovery (Hutchings et
al., 2008). A rise of this size would cause widespread devastation to Fiji's coastal infrastructure
and would be a substantial drain on Fiji's economy.
1.3.1 Natural Sources of Reef Degradation
Natural sources of coral reef degradation include cyclones, coral bleaching and invasive
predator outbreaks. 64% of all coral colonies surrounding Fiji suffered mass bleaching in
2000 and in the southern areas of Viti Levu 84% of colonies were affected (Cumming et al.,
2002). Since 2002, significant damage has been sustained on coral reefs within the Southwest
Pacific region as a result of cyclones (Lovell et al., 2004). More recently, severe tropical
cyclone Winston made a category 5 landfall over Fiji and was the strongest tropical cyclone
to hit Fiji since records began (Fritz, 2016). The impact of the cyclone towards reef health
has not yet been assessed. Coral predator outbreaks, specifically the Crown of Thorns starfish
(Acanthaster planci), have occurred on Fijian reefs since 1965, for periods ranging from two
to five years and continue to this day (Zann et al., 1990). This can be attributed to natural
fluctuations in availability of planktonic food, water salinity levels and temperature
(Lovell, 2001).
1.3.2 Anthropogenic Sources of Reef Degradation
The main anthropogenic sources of reef degradation include climate change, overfishing,
destructive fishing practices (such as dynamite fishing), poisoning, pollution, deforestation and
coral harvesting for the curio and marine aquarium trade (Lovell 2001; Teh et al., 2008).
The fisheries sector is the third largest natural resource sector in Fiji. The main sources of
foreign exchange are the tourism industry (contributing 19% to GDP), sugar industry
(contributing 8.5%) and fisheries (contributing 2.5%). Understanding the role of societal and
economic factors on fishing is critical for designing appropriate fisheries management
strategies. Teh et al. (2008) produced an overview of the socio-economic and ecological
perspectives of Fiji’s inland reef fisheries. This overview stated that there is not enough
dependable data to ascertain the status of Fiji’s reef-associated fisheries at national level.
Growing population and demand for fish since the 1990's has put continued pressure on small
scale fisheries. A socio-economic study carried out in the Beqa villages of Rukua and Yanuca
reported that, of the fish caught locally, 54% were consumed by the local community while
46% were sold to a middleman/agent, presumably to an outside source (MRIS, 2012).
Common methods for targeting reef fish species include: hand-line, spear, gillnet, seine net,
hookah (diving with surface supplied air) and reef gleaning (Teh et al., 2009). Of these
methods, hand-lining and spearfishing are used most frequently by residents of Rukua and
Yanuca (MRIS, 2012). Commercial fishing does not occur near the island of Beqa, however,
overfishing in other areas may have reduced population numbers to such an extent that
emperors species such as L. harak, L. xanthochilus, L nebulosus and B. muricatum are not
present or very rarely encountered. Other species, the Bumphead Parrotfish (Bolbometopon
muricatum), have now become almost completely extinct in Fijian waters (Cumming et al.,
2002). Lack of long term monitoring and limited technical expertise hinders assessment of the
coral reef fisheries. There have been numerous site-specific studies yet no national level
evaluation of Fiji's reef fisheries. To tackle this at a national level, the Fisheries Division, Fiji
Locally Managed Marine Areas (FLMMA) and the University of the South Pacific have
started facilitating coral reef conservation initiatives by conducting socio-economic surveys of
marine resource use.
The marine aquarium trade inflicts reef degradation in a variety of ways. According to Fiji's
Fisheries Department annual estimate, 311,097 aquarium fish were exported from Fiji in 2001.
Convention of International Trade of Endangered Species (CITES) database recorded that
169,143 ornamental fish and 31,900 invertebrates were exported from Fiji in 2004 to overseas
markets. It has also been reported that between 2000 and 2004 annual live rock exports from
Fiji increased from 800,000kg in the year 2000 to 1.3million kg in 2004 (CITES, 2004). In
2001, a reported 800,000 kg of ‘live rock’ was harvested and exported (CITES 2004); however
the actual figure is likely much greater as a substantial quantity is lost in the trimming and
grading process (Lovell et al., 2004). Live rock exports are a major problem in Fiji as it
significantly diminishes reef ecosystems by reducing the number of available spawning sites
for marine species, reducing the buffer areas for sites of increased wave action, and decreasing
carbon dioxide sequestration by reducing the amount of photosynthetic material in the marine
environment. Although this has not been observed around Beqa, likely due to tourism being
the main activity, there is potential for harvesting to occur in the future.
Pollution through sewage is a major threat to coral reefs in Fiji. Untreated sewage deposited
directly into the ocean causes increased levels of phosphates and consequently macro algal
blooms and eutrophication (Ginsberg 1994). Coral reefs are unique in that they possess low
levels of nutrients and are highly efficient at recycling them. Consequently, they can cope with
minor levels of eutrophication, however, when marine ecosystems are highly enriched with
chemical nutrients, the result is excessive plant growth in the form of macro algae. Such algae
are detrimental to the health of the reef because they use all available oxygen within the water
column, causing fish populations to die off. In addition, these algal blooms reduce the amount
of light penetrating the water column, inhibiting coral photosynthesis, subsequently causing
rapid declines in reef system biodiversity (Fabricius, 2005).
Unmanaged disposal of raw sewage is common in areas of dense population as well as in
popular tourist destinations. Villages on Beqa use pit latrines for sewage, however, because
they are close to the coast it is likely that nutrients leach through the soil into the surrounding
coastal waters and increase levels of phosphates and nitrates, which in turn negatively affect
near shore reefs. Not only is there an issue of disposal of human waste, but each village also
has at least one piggery, usually next to a watercourse or at the top of the beach (pers. obs.,
2016) leading to a heavy influx of raw sewage into the ocean. It is also unclear how the resorts
on Beqa manage their waste, but it is likely that septic tanks are employed. Incidents of
dumping on reefs along the Coral Coast of Viti Levu, Mamanuca and Suva have been
observed (Mosley and Aalbersberg, 2002, Tamata and Thaman, 2001; Zann and Lovell, 1992).
Many families on Beqa lay claim to some plantation regions which they farm, both for local
consumption and trading as well as to sell on the mainland (MRIS, 2012). It has been noted
that there has been an increase in the area of land cleared using slash and burn methodologies
to make room for these farms (pers. comm., 2015). These areas of clearing will increase
sedimentation and the rate at which fresh water is being leached onto the reef. Mangrove
forests help stabilize shorelines, filter freshwater run off and reduce the impact of natural
disasters such as tsunamis and hurricanes. In addition, many of the reef fish targeted for
consumption are known to depend on the mangroves for refuge from predators and for
ontological development (FAO, 2007, Giri et al., 2010). According to locals, the areas of
mangroves have significantly decreased and with the added impact of slash and burn
techniques this is likely to continue (pers comm, 2015).
1.4 Project Aims & Objectives
The overarching aim of the Fiji Marine Conservation project is to ascertain the health of the
reef through the use of baseline surveys in order to inform sustainable management.
Baseline surveys will be used to;
1. Identify anthropogenic impacts on the reef system.
2. Determine the effect of the current locally managed marine areas.
3. Feed into national data collection objectives through Fiji Fisheries Department and
University of the South Pacific (USP)
4. Raise awareness and education of local people as to the importance of sustained
marine management techniques with the hope to assist with the long term sustainable
use of marine resources.
2. Training
2.1 Briefing sessions
• Orientation – staff member takes new volunteers around camp.
• Bula and Welcome – staff member introduces all members of staff, other volunteers
and local Fijian family.
• Intro to duties – staff member shows new volunteers the rota and description of duties
and outlines what needs doing for each duty.
• Health and safety – staff member outlines important health and safety points for camp
and new volunteers and then take health and safety and medical tests.
• Dive and Boat Safety – Dive Officer explains the possible hazards of diving which
may be encountered as well as safety equipment used in case of an incident.
• Surface cover briefing – Dive Officer demonstrate procedure of surface cover
including emergency procedures such as emergency diver recall, deploying the anchor,
re-mooring the boat, and retrieving tired divers.
Table 1: Briefing sessions conducted during phase 171
Briefing session Presenter
Orientation JB/TF
Bula and Welcome JB/TF
Intro to Duties JB/TF
Health and Safety JB/TF
Dive and Boat Safety KL
Surface Cover KL
2.2 Science lectures
Research assistants (RA’s), with the support of staff members, are fully responsible for all data
collection on FJM. Before RA’s were permitted to conduct surveys, rigorous testing was
undertaken. RA’s were given an array of lectures, computer ID tests and in-water ID tests. A
pass rate of 95% accuracy was required for theory tests and only when theory and in-water ID
tests have been completed were RA’s allowed to start surveying. RA’s were then required to
complete two practice surveys before actual benthic and fish surveys could be undertaken and
data recorded.
The science lectures given to guide learning are as follows;
• Introduction to Coral Reefs – coral reef biology, function and threats, most common
benthic forms found along transects, and how to conduct snorkel survey.
• Mangrove Mapping – Introduction to mangroves and how to conduct transect based
surveys for mangrove mapping.
• Fish Survey Methodology – underwater techniques and processes involved in
conducting a fish survey
• Fish Anatomy – important parts of fish biology which will help identify indicator and
distinguishing features which separate families
• Indicator Fish Families – distinguishing features of indicator fish families.
• Indicator Fish Species – distinguishing features of indicator fish species
• Other Butterflies and Damsels – illustrate which species may get confused with
indicator species
• Shark Conservation – Introduction to shark conversation and threats.
• Blacktip reef sharks – information about our current pilot study.
Table 2. Science lectures conducted during phase 171
Science Lectures Presenter
Fish Survey Methodology TF
Fish Anatomy TF
Indicator Fish Family TF
Indicator Fish Species TF
Other Butterflies and Damsels TF
Shark Conservation KL
Blacktip Reef Sharks KL
2.3 Field work training
The following computer ID tests were conducted before in-water tests:
• Fish families
• Indicator fish species
• Master test – encompassing indicators, families and others
A dry run of survey methodology and an underwater spot test was also conducted in
order to reinforce techniques before conducting in-water surveys.
2.4 BTEC and Other Qualifications
No BTEC or other qualifications were carried out during phase 171.
3. Research Projects
3.1 Baseline Survey of Coral Reef Health in Beqa Lagoon
3.1.1. Introduction
Beqa Island lies within Beqa Lagoon, 10 km south of the main island of Viti Levu. The island
is known for its traditional subsistence village lifestyles, as well as hosting a number of
tourism resorts (Burns, 1994). Fiji Fisheries department currently monitor the area as part of
their national monitoring plan, however, surveys are only conducted once a year in different
areas around Fiji due to personnel restrictions.
The most comprehensive assessment conducted by Fisheries to date was a resource survey for
Yanuca and Rukua villages in 2012 by the Marine Resource Inventory Survey (MRIS) team.
The overall goal of this survey was to formulate and later implement a management plan for
sustainable use of the marine resources. Methodologies included an underwater visual census
and socio-economic surveys. It was reported that the main source of income for villagers was
fishing and that over 90% of villagers “always” or “sometimes” consumed fresh fish in a
week. Also recorded was the most common fish species caught per fishing trip, the top 5
being; E.polyphekadion, L.harak, L.atkinsoni, C.ignobilis and L.gibbus (MRIS, 2012). The
survey identified that many of the marine inshore species that usually inhabit the Beqa reef
system are under threat due to the continued destruction of the reef system through
anthropogenic activities including; pollution from pig farms, reef-walking, over-fishing,
anchor damage and the use of destructive fishing methods. It was reported that many of the
reefs in the region have a major algae overgrowth problem with large areas of reef totally
covered by algae thought to be attributed to the combination of sewage stimulating algae
growth and lack of major algae grazers from overfishing.
Indicator species are used to infer reef health trends. Indicator families (emperors,
butterflyfish, angelfish, damsel fish and barracudas) are identified to species level as there are
many interspecies variations. Angelfish show a preference for structurally complex reefs and
are not tolerant to fluctuations in physical variables such as temperature, while barracudas are
very tolerant due to ontological and seasonal shifts in habitat range (Christine, 2010).
Butterflyfish are very sensitive to reef degradation and have species dependent feeding
preferences (Carpenter and Allen, 1989). On the other hand emperors display niche
partitioning (Pratchett, 2005).
3.1.2 Survey Areas
Five survey sites were used for reef data collection;
Table 3. Survey site coordinates
Site Name GPS coordinates
Bikini S 18˚23’40.1”
E 178˚05’26.0”
Mala’s S 18˚24’10.5”
E 178˚05’58.2”
Rabbit S 18˚24’.07.5”
E 178˚06’09.9”
Wreck Reef S 18˚22’48.22”
E 178˚05’18.3”
Snapper S 18˚24’56.7”
E 178˚04’04.4”
Bikini – A near-shore site (1.29 nautical miles from camp) protected from westerly winds but is
more prone to northerly, southerly and easterly winds. Average depth is 7.5m and a gentle
slope drops down to a depth of 20 m on the outer reef. Bikini is outside of Vaqa Bay and so
will encounter freshwater dissipating out of the bay and also from the local village of Rukua.
The site is rarely visited by Beqa Lagoon Resort for tourism. Bikini is a no take zone and so
only fished on rare occasions when the chief opens the site for fishing for celebrations or
funerals.
Mala’s – An inshore site (0.56 nautical miles from camp) found within Vaqa Bay and relatively
protected from southerly and easterly winds. It is an estuarine environment with three
freshwater streams flowing into it. The majority of the reef is at around 8 m, whereas the outer
reef is at around 18 m. It is near the local village of Naiseuseu and the site is not visited for
tourism and is a non-tabu area. Targeted fish include parrotfish, unicornfish, porcupinefish,
rabbitfish, surgeonfish and goatfish.
Rabbit – An inshore site (0.44 nautical miles from camp) located within Vaqa Bay close to
river outflows. The site is generally shallow with an average depth of 6 m dropping down to 12
m at the reef edge. The site is not visited for tourism and is a no-take zone.
Wreck Reef – a nearshore site (1.97 nautical miles from camp) very exposed with a purpose
sunk wreck is located on the seabed just off the reef at a depth of 22 m. The reef has an
average depth of 8 m, however, the edge of the reef has a steep drop off down to a depth of 22
m. There can be strong currents present, however, the site is far enough away from freshwater
sources to not be affected by dissipation. The site is rarely visited by Beqa Lagoon Resort for
tourism or fishing by the locals.
Snapper – An offshore site (2.42 nautical miles from camp) relatively protected from south
easterly and north easterly winds. The reef has as average depth of 8.5 m with a drop off to 15
m at the reef edge. Six large coral bommies surround the mooring line with depths ranging 3-6
m. Transects are places on patch reefs with areas of sand.
Figure 4: Map of survey sites and FJM basecamp
3.1.3 Materials and Methods
Baseline Survey Protocol (BSP) was used following standardised Reef Check methodology
(Hodgson, 2001). In order to initially set up the permanent transects, fifty metre survey tapes
were used to create transect lines spaced 10 m apart. Four permanent transect sites were set up
at each of the survey sites and highly visible markers deployed in order to allow RAs to easily
locate the transect start points. Transect bearings were kept consistent in order to obtain
independent samples to be replicated at each site. Transect lines were laid for a total length of
50 m and this permitted 2 x 20 metre transects to be completed separated by a 10 m gap.
3.1.3.1. Indicator Fish Species Survey
Fish surveys were completed using belt transect methodology. During the fish surveyor
methodology, RAs would lay the survey tape, swim back to the start point and wait for five
minutes away from the end of the tape to allow any disturbed fish to return into the transect
area. RA’s then swam back the length of the survey tape, recording all fish seen within a 5m x
5m square from the base of the transect tape measure.
Figure 5: Fish surveyor methodology, recording all fish seen within a 5m x 5m square
from the base of the transect tape measure.
Surveyor Roles: RAs undertook various roles during fish surveys depending on the data being
collected and the level of training they had received. As four weeks were required to become
fish survey proficient, any RAs on the project for less than four weeks were unable to survey
fish and would therefore occupy another surveyor role. Data was collected on fish biodiversity,
abundance and size.
Consequently, there were two surveyor roles; physical surveyor and fish surveyor. Provided
that research assistants were able to undertake all survey roles, the allocated role rotated on a
daily basis.
The role of the physical surveyor was to lead the dive and therefore keep track of all surveyors’
air consumption, dive depth and survey time, in addition to towing the surface marker buoy.
The physical surveyor also navigated the set bearing of each transect whilst laying out the tape
measure. During fish surveys the physical surveyor remained behind the fish surveyor to
reduce disturbance to the fish within the transect area. On completion of the survey the
physical surveyor reeled in the tape.
Fish species richness, abundance and size were recorded. Research assistants learn forty-five
indicator species and twenty other fish families. Fish size was recorded in categories; 1-10 cm,
11-20 cm, 21-30 cm, 31-40 cm, 41-50 cm and >50 cm. When a fish surveyor encountered a
large school of fish, the abundance was estimated and recorded in the most common average
size category. Upon completion of a survey dive, RAs directly enter their survey data into the
master database.
3.1.4 Results
3.1.4.1. Indicator Fish Species Survey
The data obtained from the fish surveys carried out during January-March 2017 was analysed at three
different levels – indicator families, indicator species and total averages, broken down into size classes
(in increments of 10 cm), whilst considering a series of explanatory factors – distance from shore, fishing
restrictions and the differences between sites. Changes in abundances and diversity at each level were
also analysed in comparison to phase 164.
Average total fish abundance was significantly higher in the near shore than the off shore than the inshore
sites (X-squared = 13.658, df = 2, p-value < 0.01), as seen in Figure 6. Fish family abundance was higher
in the offshore sites than in the near shore than in the inshore sites (though not statistically significant - p-
value > 0.05). Fish species abundance showed the same pattern as total fish abundance, with more
individuals found on average in near shore than the off shore than the inshore sites (X-squared = 15.472,
df = 2, p-value < 0.001). There were on average 62 fish identified per transect in the near shore site, 34 in
the off shore sites and 31 in the inshore sites.
Figure 6:Average total fish abundance according to distance from shore
No significant difference was found between tabu and non-tabu areas, for either average family, species
or total abundances (p-value > 0.05), though results would indicate that tabu areas support a larger
amount of fish.
When analysing average abundances based on sites, Wreck Reef shows by far the highest total abundance
(X-squared = 70.521, df = 4, p-value < 0.0001), with an average of 93 fish identified per transect, which
is approximately three times larger than all other sites (Figure 7). The same pattern was found on the
species level too (X-squared = 71.051, df = 4, p-value < 0.0001). On the families level, no significant
difference was proved between sites (p-value > 0.05), though results indicate that Wreck Reef is again the
most abundant.
Figure 7: Average total fish abundance according to site
At Rabbit, Mala’s and Bikini more than 50% of the fish belonging to indicator families were found to be
in the size range of less than 10cm. At Snapper, the same size class made up 49.54% of individuals from
indicator families, while at Wreck Reef 54.56% of fish from indicator families are in the 11-20cm class
(Figure 8).
Figure 8: Distribution of total fish abundances across sites
There was a significant difference between size classes across fish families (Figure 9), with the greatest
majority of fish being under 10 cm (F = 15.82, p-value < 0.001). The abundance of indicator fish species
was also significantly higher in the <10 cm class (F = 9.824, p-value < 0.001).
Figure 9:Average fish family abundance according to size class
To assess the overall diversity, we calculated Shannon’s diversity indexes for each survey site, taking into
consideration both species and families. Table 4 shows Snapper to be the most diverse site (Shannon’s
index = 3.11), followed by Bikini (3.08). The least diverse site is Rabbit (2.35).
Table 4:Shannon’s diversity index for each site
The differences in overall diversities indicate that there is an increase in diversity with distance from
shore, as the inshore sites appear to be less diverse than the near shore and the off shore (Figure 10), but
no statistical significance could be found (p-value > 0.05).
Figure 10: Shannon’s diversity index in relation to distance from shore
Phase shift
Differences in abundances between phase 164 and 171 were then investigated. Figure 11 shows the
differences of total fish abundances between the two phases across sites. Apart from Snapper, at all other
sites there were significantly more fish found in 171 compared to 164 (X-squared = 33.698, df = 4, p-
value < 0.001). The same pattern was found on the species level (X-squared = 40.189, df = 4, p-value <
0.001). No significant difference was proved for indicator families abundances between phases (p-value >
0.05).
Figure 11Average total fish abundance at each survey site between phases
The tabu areas showed higher total abundances in 171, while non-tabu areas were more diverse in 164
(X-squared = 8.4054, df = 1, p-value = 0.003741).
Inshore and near shore sites were found to be more abundant in 171, while offshore sites showed higher
abundance in 164 (X-squared = 24.252, df = 2, p-value < 0.001).
3.1.5 Discussion
Indicator families are defined as families that use the reef primarily for recruitment, protection and food,
seldom straying from their respective territories. Although they are not commercially important, their
presence is indicative of a healthy reef (Hourigan et al., 1988). Indicator families are identified down to
species level for those that are most commonly seen on survey sites. This covers 4 species of angelfish,
18 species of butterfly fish, 2 species of barracuda, 4 species of emperor and 17 damsels. There are
however “others” encountered of these families during surveying.
Unfavorable weather conditions restricted access to more than 5 sites. Out of the seven visited in the
previous phase, the furthest site, Vuvale could only be visited once this phase, therefore no conclusive
data was obtained. No surveys were carried out at Milkybar this phase, as opposed to 164, as that site is
typically visited by a private resort boat from the mainland, which limits our access to the reef. Also,
when diving is possible there, crown of thorns starfish removals are carried out, as there is an ongoing
outbreak of the population, which needs to be controlled.
Offshore sites are likely to encounter lower levels of disturbance from boat traffic and are less accessible
for fishing. In addition, they are not as likely to encounter salinity, sediment, nitrate and phosphate
fluctuations as would be present at inshore sites due to their proximity to freshwater run off. One of the
inshore sites, Mala’s, showed the lowest average abundance of fish per transect. Inshore sites are closer to
areas of mangroves that are known to be vital habitats for juvenile reef fish, which may account for there
being a comparable number of families present to the offshore sites which many fish will migrate to as
they mature (FAO 2007). Of the indicator species used, angelfish are the least tolerant to fluctuations in
physical variables, especially temperature, as a temperature increase to 27 degrees Celsius triggers
gamete release (Olivotto et al., 2006). Angelfish were recorded to be in higher abundance at near-shore
and offshore sites, which supports the idea that these sites are less influenced by fluctuating physical
factors. Lower abundances of angelfish were found at inshore sites where these fluctuations will be
higher. To confirm the differences in these fluctuations between near shore, offshore and inshore sites
water quality testing would need to be conducted (Richards et al., 2012).
The lower abundance of fish stock identified during this quarter at the inshore sites can further be
explained by the more intense variations in freshwater input. As Fiji experiences heavy rainfall in the wet
season (November-April), that only intensifies the fluctuations in the chemical properties of the more
estuarine environments. Additionally, most of the indicator species that are used for this study (angelfish,
butterflyfish and especially damselfish) are typically more territorial fish (Ormond et al., 1996). This
would imply that they are more resilient to changes in the water chemical composition, unlike the
targeted indicator families which are highly migrant and therefore more likely to choose better, more
stable conditions found at the near or off shore sites (Sheaves et al., 2007).
Interestingly enough, no significant difference in fish abundances was found in relation to fishing
regulation, with both tabu and non-tabu areas showing fairly equal average values of abundances on
family, species and total levels. Coral reefs are known to be habitats that sustain a very large amount of
biomass compared to adjacent open water areas (McClanahan et al., 2016). This can explain why the
overall abundance would not change significantly in relation to fishing pressure, as the open space
created by removing certain targeted species would soon be occupied by other species, through intricate
ecological processes such as larval recruitment, post-settlement competition, predation regulation or the
lottery competition for territories (Sale, 1974; Hixon, 1991). Evidence suggests that availability of living
sites limits the populations of coral reef fishes, with similar species of fish competing for limited space on
the reef (Sale, 1978). For example, Sale demonstrated that for three species of permanently territorial
damselfish (Pomacentridae), territory was defended throughout the year, although not necessarily against
other adults, but rather against newly arriving recruits. Putting forward the lottery hypothesis, it was
suggested that priority of arrival of recruits, rather than subtle differences in requirements or competitive
abilities of adults, determines which species holds a territory.
The shift in fish size ranges that dominate the reef is also consistent with effect of fishing pressure. As
large top predators are removed from the area (as indicated by the lack of fish >30 cm surveyed and the
decrease of large fish families) there will be an increase in mid-sized (11 – 20 cm) fish species observed
(Jackson et al., 2001). This is a major shift in ecological top-down interaction. However in this quarter,
similarly to previous quarters, the dominating size class is < 10 cm. This is similar to last year’s reports
giving more support to seasonal effect in fish sizes assemblage (Cohen & Alexander 2013). In this study
carried out in the Indo-Pacific area, the results showed that the family level composition of catches did
not vary significantly between open reefs and periodically-harvested closures. Fish captured from
periodically-harvested closures were slightly larger, thus suggesting that these closures can have some
short term benefits via increasing harvesting efficiency.
A diversity index is a quantitative measure that reflects how many different types (such as species) there
are in a dataset, and simultaneously takes into account how evenly the basic entities (such as individuals)
are distributed among those types. The value of a diversity index increases both when the number of
types increases and when evenness increases (Tuomisto, 2010). For a given number of types, the value of
a diversity index is maximized when all types are equally abundant. Diversity analysis revealed Snapper
and Bikini as the most diverse sites this phase. For the off shore site, Snapper, this can be explained by
the fact that the reef is subjected to enough variation to allow changes in species composition due to the
constant opening up of new spaces that can be claimed by different individuals from various species.
There is also the high possibility that Beqa lagoon has transient fish species that use the further reefs as
either breeding or hunting grounds (Cohen & Alexander, 2013). Because of this the enforcement of the
no take area or “tabu” area is essential to help the recovery of fish stock
Fishing is prohibited by local management practices at Bikini, which has the highest overall diversity.
This is a strong indication that fishing pressure has an effect on the composition of fish populations on
the reefs. This could mean that “tabu” areas in Beqa may be effective in recovering fish stock. There are
many instances where locally managed marine protected areas have been essential to the health of the
reef. This is good news for the reef system in Beqa. The management procedures employed by local
communities has shown to maintain and encourage a healthy ecosystems in terms of overall diversity
The least diverse site is Rabbit, which is the closest reef to shore and is also a designated no-take zone.
Therefore there is not a lot of disturbance caused to the natural equilibrium of the population as a result of
the non-existent fishing pressure. This would result in a uniform population assemblage with little
variation throughout the phase.
Aims for the next studies in the coming phase include developing the benthic life form
projectby focusing on a survey protocol that would allow to get a better picture of the
composition of the sites and potentially identifying new survey sites. Ideally, an even number
of tabu and non-tabu sites in each of the distance classes (inshore, near-shore and off-shore).
Also, seeing as Beqa lagoon expands over a much larger area than we generally have access to,
we aim to improve our relationships with other villages on the island so that we could get
permission to regularly visit a series of other sites.
3.2 Mangrove Mapping in Vaga Bay
3.2.1. Introduction
Mangrove forests occur on low energy, sedimentary shorelines of the tropics, between mean tide and high
tide elevations (Molony et al., 1995). Mangrove trees have physiological and morphological adaptations
to the environmental stresses of their intertidal habitat, of high salinity, low oxygen, poor nutrient
availability and substrate mobility (Duggan, 2003). These cause different mangrove species to prefer a
particular elevation between mean tide and high tide. True mangrove species occur exclusively in this
saline wetland environment, with adaptations such as aerial roots and halophytic strategies (Molony et al.,
1995, Duggan 2003).
Mangrove ecosystems provide a useful buffer between the land and the sea. Mangrove forests are a sink
for sediment and nutrient-rich runoff, protecting nearshore waters from eutrophication and turbidity to
benefit seagrass and coral reef health (Peters et al., 1997). They also provide protection of the land from
marine inundation during storms. Mangroves have been shown to be important fish habitats, particularly
functioning as a fish nursery (Lal et al., 1984). Mangroves sustain a food chain within the mangrove
habitat, and tidal export of mangrove material supports offshore food chains (Ley et al., 2002). Many
species of fishes, crustaceans, molluscs, amphibians, reptiles and birds are found in mangroves (Lal et al.,
1984, Ley et al., 2002)
Mangrove wetlands are one of the most threatened natural communities worldwide, with about 50% of
the global area lost since 1900, and 35% of the global area lost in the past two decades (FAO, 2003;
Spalding et al., 2010). Human activities remain a major cause of degradation and loss of mangrove
ecosystems in all parts of the world, including the Pacific Islands region (Polidero et al., 2010).
Monitoring will measure mangrove extent and condition, and allow mangrove ecosystems to be
conserved and managed sustainably to maintain their environmental, ecological, and socioeconomic
benefits.
Mangrove ecosystems are also sensitive to climate change impacts, particularly to associated relative sea
level rise. Inter-tidal mangroves are most extensively developed on sedimentary shorelines, where mud
accretion determines their ability to keep up with sea-level rise (Gillman et al., 2008). The IPCC 4th
Assessment projected a global sea level rise of 0.18-0.59 m by 2099 (1.5-9.7 mm per year), and
mangrove accretion rates are usually less than this, resulting in dieback at the seaward edge, and inland
recruitment. Rise in temperature and the effects of increased CO2 levels should increase mangrove
productivity, change phenological patterns, and continue expansion of mangrove species ranges into
higher latitudes (Gillman et al., 2008).
Fiji has the third largest mangrove area in the Pacific Island region, after PNG and the Solomon Islands.
Mangrove areas are one of the better wetland types inventoried in the Pacific Islands (particularly Fiji),
though the information sources are fairly dated (Watkins, 1999). The mangrove area was estimated by
Spalding et al., (1997) from a forest cover map prepared by the Ministry of Forests, Fiji based on a 1985
survey, with mangroves distinguished using the Fiji Forest Inventory carried out in 1966-9. This gave a
total mangrove area for Fiji of 517km2. Largest areas are on the SE and NW Viti Levu shorelines, and the
northern shore of Vanua Levu (Richmond and Ackermann, 1974). Only 19.7 km2 of mangrove was
recorded for Fiji by Saenger et al., (1983).
Rehabilitation of degraded mangrove and inshore reef areas will increase their resilience to climate
change effects. Site selection should consider value for money, the level of community or stakeholder
support, benefits to adjacent systems and the relative risk of sea-level rise. Any rehabilitation program
should initially remove the stress that caused decline, decide on whether to use natural regeneration or
active replanting techniques, in which case use of local sources of seeds or juveniles will reduce loss of
genetic variation across Fiji.
3.2.2 Restoration Area
A survey done by the WWF (2014) showed that Beqa Island is one of the major mangrove habitat in Fiji,
housing approximately 0.72 km2 of mangrove. Vaga bay is the largest bay on the west side of Beqa
Island. It is approximately 1.2 km wide and 1.5 km deep inshore. There is mangrove wetland present
along the inside of the bay which is the characteristic of the sheltered bay area. There are two villages in
the bay: Rukua which is located on the north part at the mouth of the bay and Naiseuseu which is located
in the south part inside the bay. Both of these villages fish in the bay as part of their livelihood.
Mangroves have been shown to be important fish habitats, particularly functioning as a fish nursery,
therefore it is beneficial to restore the mangrove wetlands in the Bay.
Figure 11: Aerial photograph of planned restoration area in Vaqa Bay, Beqa Island, marked by red
square. Frontier Fiji Marine basecamp marked by red pin. (Source: Google Maps)
Approximately 12.600 m2 of Mangroves wetland was mapped throughout the 161 and 162 quarters. Four
species of true mangroves and one species of associate mangroves have been found (Figure 12). Two
genera of true mangroves are found in the wetland: black mangroves (Bruguiera gymnorhiza) and the red
mangroves (Rhizopora stylosa, Rhizopora samoensis, and Rhizopora x selala). The one associate
mangrove species (Barringtonia asciata) is found by the high tide line and cover approximately 11% of
the wetland. Canopy cover are mostly uniform with only 5% of bare patch throughout the area. Damage
observed on the trees is mostly storm damage. High tide mark varies around 50 – 60 cm on the landward
edge and around 90 – 110 cm on the seaward edge. Seaward edge is littered with recruitments; most of
them are black mangroves.
Figure 12: Distribution of Mangrove Species in Vaga Bay
Restoration area is planned on 1,032 m2 of bare wetland on the north side of present mangroves (Figure
11). The area is divided into 4 zones, in which zones 1 -3 will be restoration area and zone 4 will be
nursery area where we grow propagules up to transplantable size (Figure 13). The zones are further
divided into seaward and landward zones. Red mangroves (Rhizopora spp.) will be planted on the
seaward zones while black mangroves (Bruguiera spp.) will be planted on the landward zones following
the pattern of present mangroves. Walls are built to protect propagules from wave action and to retain
nutrients from land, with gaps to allow circulation. Freshwater is provided by a creek on the north side of
the mudflat. Regular rainfall will also help provide freshwater necessary for the propagule to grow.
Figure 13:Plan for mangrove restoration area in Vaga Bay
9%
7%
21%
47%
11% 5%
Rhizopora stylosa
Rhizopora samoensis
Rhizopora x selala
Bruguiera gymnorhiza
Barringtonia asciata
Bare
3.2.3. Materials and Method
3.2.3.1. Wall building
The walls are built by stacking rocks in a chicken wire frame. Each wall will be 10 m in length, 75 cm in
height, and 50 cm thick. The rocks for the wall will be collected from the beach and creek area. This
method will allow water move through the small gaps on the wall while protect against wave action
effectively.
3.2.3.2. Propagule collection
RAs are deployed in groups of 4 on mid tide and comb the tideline for viable red and black mangroves
propagules (Figure 14). Viable propagules have visible budding and form root nubs, the body of the
propagules should be whole without cuts or gouges. Only viable red mangroves propagules were
collected in 171.
Figure 14:Viable and non-viable mangroves propagules
3.2.3.2. Planting
Red mangroves propagules are planted in a row approximately 1 m apart from each other. Approximately
10 – 12 rows are planted on every seaward zone. Since black mangroves grown naturally sparser than red
mangroves, propagules will be planted in a row approximately 3 m apart from each other. Approximately
3 – 4 rows will be planted on every landward zone. Circle of small rock will be arranged around each
propagule to assist in rooting and second protection against wave action aside from the wall.
3.2.4. Results
The wall in Zone 1 is under construction. So far it is 10 m long, 40 cm high and 30 cm thick. Current wall
is not held together by chicken wire and will have to be reconstructed in the near future.
Red Mangrove Black Mangrove
Non-viable Viable Non-viable Viable
One hundred and twelve viable red mangrove propagules are collected and planted in zone 1 seaward at
the beginning of 163. Monthly survey to observe the survival rate of the propagules showed that ~60% of
the propagules survived the quarter and are growing healthy leaves (Figure 15).
Figure 15: Propagules survival rate
Table 5: Mangrove restoration area and propagule status
Zone Wall length
Existing
beginning
171`
Surviving
end 171
Average
size
beginning
171
Max size
beginning
171
Average
size end
171
Max size
end 171
1 10m 60 58 45cm 90cm 60cm 100cm
2 6.5m 22 22 25cm 45cm 30cm 55cm
3 5m 96 16 - - 20cm 35cm
At the beginning of phase 171, 96 red mangrove propagules were planted, out of which 16 have survived
until the end of phase, which shows a survival rate of aprox. 17%. The propagules previously planted in
zone 2 during phase 164 have all survived throughout this last quarter and are steadily growing (5cm on
average). The propagules in zone 1 that were planted at the beginning of phase 163 have reached an
overall survival rate of ~50%, as there are now 58 young mangroves growing, with an average length of
60 cm recorded at the end of phase 171.
3.2.5 Discussion
The survival rate of the propagules this quarter is very low compared to phase 163, which can be
explained by the fact that during cyclone season (November-April), the propagukes are exposed to very
intense wave action. However, studies have shown that mangroves propagules will be able to survive
wave action after they reach ±1m in height (Robertson & Alongi 1992, Allen & Duke 2006), therefore
adding up to the wall until it is 75 cm at least will increase the survival rate of the propagules even more.
0
20
40
60
80
100
120
July August September
Nu
mb
er
of
Prp
ag
ule
s o
n Z
on
e 1
Holding together the wall with the chicken wire will also help the wall to stay together in the occasion of
strong wave action (Pers comm. 2016)
The mangrove wetland seems to be healthy with uniform canopy cover. This indicates that the area was
relatively free of direct anthropogenic impact such as piggeries, garbage, or illegal cutting (IPCC 2007).
The wetland also produces a good amount of viable propagules that are readily accessible for the
restoration effort. This is obvious in the more than one hundred viable propagules collected within one
month. Studies show that propagules from nearby mangroves are more likely to survive when planted as
the environment has already proven to be able to sustain the growth of the mangroves (Prance 2001,
Allen & Duke 2006, Spalding et al., 2010).
The average survival rate of propagules in the wild is 15% within the first two months (Smith 1992,
Sheue et al., 2005). The average survival of propagules in restoration project in Fiji varies greatly. The
restoration in Lambasa, Vanua Levu have 30% survival rate within the first two months (Molony &
Sheaves 1995) and the restoration in Sigatoka, Viti Levu has 55% survival rates (Krauss et al., 2014).
Based on this, the survival rate of the propagules in zone 1 is still very high, which indicates that in the
future, continued restoration work can show promising results.
3.3. Identifying Blacktip Reef Shark Nursery Grounds
3.3.1. Introduction
Fijian waters play host to a wide variety of elasmobranch species; from large, highly migratory sharks to
coastal dwelling rays and reef sharks. Beqa Island is known globally for precisely this reason.
Blacktip reef sharks, Carcharhinus melanopterus, are commonly sighted around Beqa and are an
extremely important predator within reef systems globally (Papastamatiou et al., 2009a). They are a
coastal species found in tropical and sub-tropical reef systems (Fowler et al., 2005). They can reach a
maximum length of 1.8m with females growing larger than males (Mourier & Planes, 2013a) and are
easily recognised by prominent black tips on the fins, especially the first dorsal and caudal fin. They
favour shallow sand flats and coral reefs, using reef systems as primary hunting grounds. Blacktips are
apex predators in many reef systems (Mourier et al., 2013), including those in Beqa lagoon. This allows
them to exert top-down effects on the ecosystem, having an above average effect on ecosystem processes.
This makes it imperative to protect them in order to preserve the health of the reef and its associated
species.
Globally, elasmobranch species are in a state of severe population decline (Fowler et al., 2005). The
IUCN 2014 Red List classed blacktip reef sharks as 'near threatened' in their 2014 review (Dulvy et al.,
2014). The main causes for decline in blacktips are fishing pressure, both for meat and fins, and through
bycatch. However, sharks in Fiji are relatively well protected. Fijian culture dictates that sharks are
sacred and are forbidden to be caught in numerous villages (Rasalato et al., 2010). The local people of
Beqa and Yanuca in particular recognize a shark god, Dakuwaga, and there is a lot of superstition
surrounding the harming of sharks (pers. comm., 2016). However, Fijian shark populations may still be
threatened by foreign fishing vessels in their waters and the demand for shark fins internationally.
An effective way to protect a species is to focus conservation efforts upon areas of key ecological
significance; for example nursery grounds (Hueter et al., 2005). The concept of nursery ground use by
some elasmobranch species has been widely recognized in scientific literature for decades (Heupel et al.,
2007). These are generally classed as 'an area where young are born and reside as they grow towards
maturity' (Heupel et al., 2007), which is a common life history strategy in many fish species (MSEL,
2014). Genetic studies have identified this behaviour in black tip reef sharks in French Polynesia
(Mourier & Planes, 2012). Natal philopatry has also been identified within the species whereby females
return to the same area for parturition, although they tend to stay within the area of the island that their
home range is associated with (Mourier & Planes, 2013; Porcher, 2005). Blacktip reef sharks in particular
have very small home ranges with high site fidelity (Papastamatiou et al. 2009b), suggesting at least one
nursery area must be present around Beqa island and the surrounding lagoon. This phenomenon results in
genetic heterogeneity between sub-populations meaning that each individual stock requires protection to
preserve species genetic diversity (Hueter et al., 2005).
However, there is no definitive method for correctly identifying a nursery area. Heupel et al., (2007)
proposes classifying it under three key characteristics:
• Sharks are more commonly encountered in the area than other areas
• Sharks have a tendency to remain or return for extended periods
• The area or habitat is repeatedly used across years
These are widely accepted characteristics of elasmobranch nursery grounds and will be referred to
regularly throughout this study. It is also important to account for the size ratio of the population when
identifying nursery areas. If the population in the proposed area has a high proportion of juveniles it will
also be an indicator of a nursery ground (Duncan et al., 2006).
Beqa has many possible bays and shallow areas that could be potential nursery grounds for blacktip reef
sharks. Juveniles are usually found in shallow water over sandy flats, often only a few metres deep
(Papastamatiou et al 2009b). They are also known to inhabit mangrove swamps and can often form large
groups. The Sandbar was selected as an initial point of study due to a high number of juvenile and adult
blacktip sightings while on recreational visits.
Figure 16: Location of Sandbar at S 18° 28’ 48.9” E 178° 3’ 20.0”, 5.37 nautical miles from
camp(Picture sourced from Google Earth)
Sandbar is positioned on the lagoon side of the barrier reef, to the shout-west of Beqa Island (Figure 16).
It is frequently visited by tourists, primarily from the Royal Davui, Lawaki Resort and Beqa Lagoon
Resort, increasing boat traffic and noise pollution to the surrounding marine environment. It is also
subjected to a high level of fishing pressure from residents of Beqa, both using long lines and spear
fishing. Beqa residents know it as a place where sharks are seen frequently, particularly blacktips.
Work carried out in phase 164 confirmed that there is indeed a nursery at the Sandbar, therefore this
phase has been focused around finding the best methodology for monitoring the juveniles. The main
factor that was taken into consideration was tide elevation.
3.3.2. Methodology
Following selection of the sandbar as one of the initial study sites, 3 trips have been conducted so far for
reconnaissance and to work out the finer points of the methodology. Initially, the sandbar was divided
into two study areas as their depth and topographies vary significantly (Table 5). Both sites extend for
50m from the edges of the sandbar.
Table 6: Survey site specifics
Site Depth Range (m) Topography
Sandbar 1 – facing barrier reef 0.5 – 2.5 Mainly reef with occasional
sandy patches, small wreck
close to barrier
Sandbar 2 – facing Beqa Island 0.5 - 14 Large sandy area with the
occasional coral bommies
Snorkel surveys were deemed most appropriate due to the relatively shallow depth ranges of the sites. It
is also less disruptive without the bubbles, and therefore the noise, generated by the use of scuba; in fact
sharks are seen on our dive sites more often by snorkelers than divers (pers. obs. 2016).
Two attempts were made to test the initial hypothesis, and the surveys were done within an hour before
and after high tide. The conditions proved to be unfavourable to allow any other counts to be made
without leaving the boat. At high tide the sandbar is covered in water too deep to allow wading, and the
waves breaking over the sandbar made it unfeasible for snorkelling, due to particularly strong currents.
Alternatively, visiting the sandbar in a timeframe of a couple of hours before and after low tide showed
better results. As the conditions were much calmer, during the next three trips it was possible to go
snorkelling on the reefs around the sandbar, which allowed better observations of the juveniles, through
close encounters (up to less than 50 cm) and longer interaction times (up to one minute).
3.3.3. Results
The blacktips are initially seen in large aggregations (up to 12 individuals), consisting of juveniles and
sub-adults, and after they detect the presence of surveyors, they disperse in smaller groups of 3-5
individuals. The presence of surveyors does not appear to cause any alteration to their behaviour, as the
sharks did not leave the area after the first encounter. They seemed to be interested and curious about the
human presence, rather than feeling threatened or intimidated. The juveniles do not seem to be affected
by boat noise either, as no avoidance or escape behaviour has been observed when approaching the
Sandbar by boat. This can also be a result of the fact that the area is visited regularly by other vessels,
either local fishing boats or private resort guests. The sharks were present in the area throughout the
entire duration of the survey (approx. 30 minutes), swimming in the shallow reefs around the Sandbar.
Interestingly enough, one of the three trips that were made at the Sandbar at low tide showed very
different results in comparison to the other two (Table 5). Just two sharks were seen during the entire
survey, which were also not present for more than 15 minutes.
Table 7. Blacktip surveys in phase 171
Survey Date Tide
elevation
Time
(aprox) Surface/snorkelling
Sharks seen at
one time
1 24/01/2017 High 2pm Surface 9
2 05/02/2017 High 3pm Surface 7
3 23/02/2017 Low 9am Snorkel 10
4 10/03/2017 Low 10am Snorkel 12
5 16/03/2017 Low 2pm Snorkel 2
3.3.4. Discussion
A potential explanation for the unusual results found on survey 5 can be the time of day, as that particular
trip was done much later (around 2pm) than the previous two (which took place early in the morning – 8-
10am). This is however just an assumption, and further investigation is needed. Not much is known in
terms of blacktip reef sharks diel activity habits, so there is currently no exact understanding of this.
The Sandbar has a lot of artisanal fishing pressure from fishermen local to Beqa and Yanuca (pers. obs.,
2016) so it is surprising that this does in fact seem to be an often frequented nursery ground. However it
could also explain why the juveniles do not leave as soon as we arrive in the area; they would be used to
the boat noise and fishermen wading on the surrounding reefs. Sharks are not fished in Beqa due to local
customs (pers. comm., 2016) and for this reason, these sharks would not be chased or caught if seen in
the area and so would have no fear of people. If by chance they were caught on a line, they are always
thrown back so there is zero fishing pressure on the sharks themselves. Given the number and the size of
sharks we have seen in the surveys so far, it would suggest that they tend to stay in the area whilst young.
However, conclusions drawn from data of such a small sample size are speculative at best. Continued
surveying is crucial to determine if this is in fact a nursery for blacktip reef sharks. Continuing study will
refer to the guidelines set by Heupel et al., (2007):
1. Sharks are more commonly encountered in the area than other areas
2. Sharks have a tendency to remain or return for extended periods
3. The area or habitat is repeatedly used across years
To meet these criteria, as many new sites as possible need to be added to draw valid conclusions. Further
studies will target sites in several locations where the right habitat type is found, in conjunction with
discussions with local fishermen who are knowledgeable about the various different qoliqoli’s (traditional
fishing grounds for each village) in Beqa Lagoon. This aims to first of all find other potential nursery
grounds, but also to ensure that guideline 1 can be confirmed regarding Sandbar – if we find other areas
with similar favourable conditions and habitat type without juvenile blacktips, it would suggest that
Sandbar is preferred as a nursery area as they are more commonly encountered there. We will also
continue to visit Sandbar to try to meet the criteria for guideline 3, surveying over a longer period of time.
In order to properly monitor a shark nursery, a method of tagging individuals would be necessary. Even
though it has been shown that blacktip reef sharks have a relatively small home range that they spend
most of their life in, currently there is no way of confirming that the individuals seen at the Sandbar are
the same ones on every survey. It is also not clear where the blacktips go once they reach maturity, as no
fully grown adults have been seen at or in the vicinity of the Sandbar.
Further reconnaissance around the Sandbar, carried out prior or post surveying has revealed the presence
of blacktips in the other shallow sandy areas surrounding the reefs. These individuals are generally larger
than the ones seen in the big groups while snorkelling, which would indicate a modification in behaviour
with age, towards a more solitary lifestyle.
The area of the Sandbar where the sharks have been most abundant is the one facing the barrier reef,
which is much more protected from strong currents or waves. So far, no individuals were seen on the side
facing the lagoon.
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4. Acknowledgement
We would like to thank the family that owns the land we operate from who have been crucial for our
fieldwork. Thanks also to all of the RAs who have been working hard in collecting all of the data.