Reports of the actual impacts of the tsunami on fisheries resources are few, with most studies being undertaken on sensitive ecosystems such as coral reefs and mangroves by conservation groups and organizations. Because these ecosystems and others in coastal areas are the support systems for fished resources, the effects of the tsunami on them were reviewed to determine whether effects on the fisheries resources could be demonstrated over the longer term.
Most of the reports of significant or extensive damage due to the tsunami came from initial rapid assessments (Chavanich et al. 2005; CORDIO and IUCN 2005; Kulkarini 2005) and focused on coral reefs. This is not surprising because a priori rapid assessments are designed to detect damage and quickly zero in on the worst affected areas. More formal quantitative assessments of impacts are usually more objective and focus on detecting changes in abundance, cover and diversity compared with pre-impacted conditions. They usually include damaged and undamaged sites in a logical framework designed to estimate geographic extent. Both types of studies were included in this review, but it appears that evidence from quantitative surveys are likely to give a more accurate picture of the real extent of impacts of the tsunami on fisheries resources. Further, because the review focussed on information from Aceh and Sri Lanka, the two hardest hit areas, it is fair to assume that the findings of this review findings cover the worst cases of impacts, which therefore could be generalized to imply lesser effects in surrounding countries.
The overwhelming evidence available in the studies reviewed suggests that the tsunami had relatively minor impacts on fisheries resources and the ecosystems on which they depend. There were cases, described hereunder, in which effects were measured, but these were localized and of little significance from a local, provincial, national or regional fisheries perspective. Of far more importance is one message that is repeated in many of the studies. Ongoing anthropogenic impacts and misuse of resources already firmly entrenched throughout the region prior to the tsunami are far more important in determining the status of resources than the effects of the tsunami or any other rare natural disturbances. As Foster et al. (2006) put it, "sedimentation (exacerbated by the tsunami), overfishing, and the use of destructive fishing methods may represent a greater threat to Aceh's reef ecosystems than the immediate impacts of the earthquakes and tsunami". The sections that follow review the evidence covering effects on fished resources, the ecosystems that support them, interactive effects and changes in fishing effort that accompanied the tsunami.
In Aceh, LIPI (2006) and LIPI and IMR (2006) reported that the total catch of pelagic fish, species composition and size distribution declined in Aceh from 2003 to 2005. This study concluded that the changes observed were unlikely to be due to the tsunami. A similar result was reported from Maldives where a study of fisherfolk's perceptions was undertaken on the effects of the tsunami on bait fish (mostly sprats, anchovies, silversides, but including reef-associated cardinal fish and fusiliers) for the pole-and-line fishery. Surveys were undertaken in three atolls: Laamu and Thaa with high impacts and Baa with medium impacts, with additional information collected from fisherfolk landing their catches in Malé fish markets (Gunn et al. 2005). Although five respondents reported negative impacts on bait fish resources, the majority (122) from the three outer atolls reported that bait fishing was average or good (January to February 2005), concluding that it was similar or better than the period immediately before the tsunami. In Malé, 68 respondents landing primarily from Kaafu Atoll (nearby) reported that bait fishing was poor, but most attributed this to normal seasonal effects — relating this to post-tsunami increases in turbidity and perceived habitat damage, and normal seasonal effects (Gunn et al. 2005).
A research cruise undertaken by LIPI, the Research Centre for Oceanography and IMR, the Institute of Marine Research, Norway in 2005 concluded that demersal fisheries have been in decline since 1980 (LIPI and IMR 2006). They did not report specific impacts of the tsunami on demersal species, but warned that alterations to the benthic substratum (tsunami deposits and habitat damage) could lead to long-term impacts on demersal fish through changes in the benthos (their food).
Surveys carried out on demersal fish along the Andaman Coast of Thailand over seven cruises on Pramong IV in 2004 and 2005 showed an increase in catch per unit of effort (CPUE) and stock densities after the tsunami (LIPI and IMR 2006). CPUE increased from 35.2 kg/hour in 2004 to 42.7 kg/hour in 2005, while stock densities increased from 345 to 430 kg/km2 over the same period. The differences were reported to be significant for total catches (of demersal fish), cephalopods and crabs (Figure 9), but varied according to sites within the area surveyed. Off western Phang-nga and Phuket Provinces, abundances of marine fish decreased to one-third of levels before the tsunami, while in Phang-nga Bay, abundances of cephalopods and shrimps were higher after the tsunami (LIPI and IMR 2006).
Two research cruises were undertaken off Kedah and Penang by the Fisheries Resource Branch of the Malaysian Fisheries Research Institute (Ahmad et al. 2005a, b) (Table 3). The purpose of the surveys was to undertake post-tsunami trawls in areas that had been sampled before the tsunami to identify any changes in the density and/or composition of fish and invertebrate catches in tsunami-affected areas. The catch results were also examined to determine whether there might be differential effects on fisheries stocks according to depth (<30 metres, >30 metres), habitat preference (demersal or pelagic) or trophic level (omnivores, mid-level carnivores or high-level carnivores).
Figure 9: Stock biomass of major fished groups in 2004 and after the tsunami in 2005 as surveyed in the Pramong IV cruises off Thailand's Andarman Coast
Data are overall results from LIPI and IMR (2006) and are converted from percent of catch contributed by each group to kg/km2.
At Kedah, there appeared to be a temporary increase in density and diversity of up to 286 percent for fished species, including demersal fish and demersal and pelagic invertebrates. This occurred two months after the tsunami, but returned to "normal" levels when five months had elapsed. Off Penang, although some changes were observed, they were statistically not significant. In both studies, the authors concluded that the impacts of the tsunami on fished resources were probably low and that changes in fishing pressure were likely to be more significant.
Researchers from Kochi, India at the Cochin University of Science and Technology, NIO-RC, Annamalai University and the Centre for Marine Living Resources and Ecology (CMLRE) and Cochin Marine Fisheries Research Institute (CMFRI), undertook a research cruise aboard the FORV Sagar Sampada, followed by additional studies in January 2005. Their purpose was to carry out detailed investigations on the impacts of the tsunami on the benthic communities, sedimentation, water chemistry and productivity patterns of the coastal waters off Kerala, Tamil Nadu and Andhra coasts and the Andaman Sea (Sampath 2005). Using baseline data from previous cruises, results were reported separately for the cruise tracks surveyed.
Along the Kochi–Chennai track the team found no significant effects on the major groups of benthic organisms in samples taken between 30 and 100 metres depth. There were similarly no observed effects on demersal fishery catches, nor any sign of algal or zooplankton blooms. On the Andaman–Chennai track the team found high levels of sedimentation, nutrients and dissolved oxygen which they implied promoted phytoplankton production in the nearshore waters of Viper Island and Minnie Bay, where the tsunami waves were high.
In a detailed study that included coral reef fish in Aceh, Campbell et al. (2006) found no clear evidence of disturbance to the reef fish assemblages of northern Aceh. Further they concluded that because they detected no major change in benthic habitats it would be highly unlikely that reef fish would be adversely affected by the tsunami in indirect ways. Campbell et al. (2006) suggested that these results be treated cautiously because data from before the tsunami were generally lacking. They found that the overall abundance of fish was high at a site where damage to corals was most pronounced, compared to another where there was very little damage to corals.
In another study in Aceh, low abundance and small mean size of the ten primary food fish families was attributed not to the tsunami, but to overfishing. Evidence of destructive fishing practices was common. Overfishing can lead to an imbalanced ecosystem in which the lack of herbivorous fish allows fleshy algae to overgrow corals and dominate the coral reef (Foster et al. 2006).
In Sri Lanka rapid assessments of the impacts on coral reef fish put the damage due to the tsunami at relatively high levels. Loss of small reef fish was noted in four out of six locations across the affected parts of the country, in association with significant damage to reefs. In Dutch Bay where reef damage was considered extreme, fish life was reduced drastically (NARA et al. 2005; Rajasuriya 2005). The main groups affected were damsel fish, butterfly fish, wrasses and surgeon fish.
An important part of this study was consultation through participatory rural appraisals (PRAs) of affected fishing communities in Aceh and Sri Lanka to determine the status of fisheries, fisheries resources and ecosystems. This work was undertaken in Indonesia (Aceh) and Sri Lanka by teams of national consultants between March and July 2006. The aim of the PRAs was to discuss fisheries resources and fishing pre- and post-tsunami to identify: (i) status and trends prior to the tsunami; (ii) the impacts of the tsunami; and (iii) gather people's opinions on how their fisheries should be managed in the future. These studies were focused on the perceptions of fisherfolk and others involved in fisheries, acknowledging that they are likely to have significant anecdotal knowledge of their resources and fishing behaviour. Fishing communities are also those that are most directly affected by any changes resulting from the tsunami and will be part of management strategies that may follow. It should be noted, however, that the PRA assessments were carried out in post-emergency conditions in both countries and results may be influenced by the trauma experienced by communities and the limited capacity of facilitators.
Communities and fisherfolk groups were approached through structured focus group discussions and key informant interviews. In Aceh, at least six focus group discussions involving six to 12 people and five key informant interviews were carried out in each of the eight sites (Aceh Jaya, Pidie, Lhokseumawe, Idi, Langsa, Aceh Barat, Aceh Besar and Banda Aceh) (Tampubolon et al. 2006). The surveys undertaken in Aceh are incomplete and have not been fully analysed for all sites.
In Sri Lanka surveys were undertaken at 11 sites within the tsunami-affected districts of Galle and Hambantota, with additional information collected at three sites in Kalutara (Maldeniya and Jayamanne 2006). Although 12 coastal districts in the country were affected, the studies focused on Galle and Hambantota because of the importance of fisheries on the economy of the districts, the presence of many fisherfolk and fisheries and the magnitude of impact on the resources and habitats. Kalutara District, also heavily impacted, was included to provide information on the important beach seine fishery. The sites selected were: Galle – Balapitiya, Maduganga Estuary, Ambalangoda, Rathgama Lagoon, Galle Harbour and Galle Dewata; Hambantota – Mawella Lagoon, Unakuruwa, Rekawa Lagoon, Kahandamodera and Kirinda; and Kalutara – Payagala, Beruwala and Maggona. In each area all (fisheries) cooperative societies and environmental organizations were interviewed, but community members involved in the group meetings were sampled and not selected by any specific criteria. Approximately 25 to 100 people participated in each meeting. Additional environmental assessments were made by the survey team at each site.
The information obtained through these meetings focused on: (i) historical maps of major fisheries and ecosystems with key events; (ii) identification of the impacts on fisheries and ecosystems; (iii) fisheries seasonal calendars and impacts of key events; (iv) identification of direct and indirect impacts by key events; and (v) community perceptions on mitigation. The main fisheries examined in the study were defined by a combination of habitat, gear and species identifiers and included demersal, lagoon, small and medium pelagic and beach seine fisheries; as well as the crustacean and chank fisheries. The ecosystems examined included estuaries, lagoons, mangroves, coral reefs, shallow seas and sandy and turtle-nesting beaches (Maldeniya and Jayamanne 2006).
Overall, the size of animals and species composition of catches remained the same after the tsunami at all sites (Table 4). Fisherfolk did, however, report an increase in prawns at Aceh Jaya, particularly in areas from which mangroves had been lost. Overfishing was reported at all sites, which at Aceh Jaya concerned lobsters. It is not clear whether this refers to general overfishing, or overfishing as a result of the tsunami (e.g. emergency fishing). At most sites, participants noted that catches had declined as a result of the tsunami at five of the eight sites and that fishing grounds were now located further offshore. It is not clear whether the greater distance to fishing grounds was thought to be a result of changes in the grounds themselves or overfishing. At Aceh Jaya human populations close to fisheries landing sites were smaller than pre-tsunami levels. Boat ownership declined as a result of the tsunami at five sites, but actually increased at Pidie. At one site (Idi) boats provided by donors after the tsunami were considered inappropriate and could not be used for fishing. Participants reported some environmental damage, including a loss of between 100- and 300-metre strips of coastal land and loss of mangroves at Aceh Jaya. At Aceh Besar, fisherfolk reported that damage to the mouth of the river impeded their access to the sea. Most participants reported that they thought that catches had declined in their area compared with five years previously (including non-tsunami declines). Pidie was an exception: Fisherfolk reported an increase in catches over the last five years, with a decline since the tsunami.
|
Table 4: Summary of main PRA results from 8 sites surveyed in Aceh Province |
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|
Data are from Tampubolon et al. (2006) with � No change; � Increased; ò Decreased; ● Greatly decreased. |
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|
Aceh |
Pidie |
Lhokseumawe |
Idi |
Langsa |
Aceh |
Aceh |
Banda |
|
|
Impacts of the tsunami |
||||||||
|
Size |
� |
� |
� |
� |
� |
� |
� |
� |
|
Species |
� |
� |
� |
� |
� |
� |
� |
� |
|
Abundance |
� |
|||||||
|
Overfishing |
Lobster |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
|
Catches |
� |
� |
� |
● |
� |
� |
� |
|
|
Fishing grounds |
� |
Further |
Further |
Further |
Further |
Further |
||
|
Boat ownership |
� |
� |
� |
� |
� |
� |
� |
� |
|
Role of women |
� |
� |
� |
� |
� |
� |
� |
� |
Role of children |
� |
� |
� |
� |
� |
� |
� |
� |
|
Environmental change |
100–300 m coastal land lost; mangroves lost |
� |
Damage to river mouth |
|||||
|
Other changes not related to the tsunami |
||||||||
|
Catches compared with 5 years ago |
� |
� |
� |
� |
● |
� |
� |
�* |
|
* This decline appears to refer to three years ago instead of five. |
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Participants in the PRAs made recommendations on strategies for recovery and management of their fisheries. The main recommendations made across all of the sites were:
Participants of the PRA surveys held in Sri Lanka identified a wide range of changes in their local fisheries and ecosystems (Table 5), some of which were confirmed by analyses of historical catch data (Section 5.1) and site assessments undertaken by the team. During the PRA fisherfolk identified cases in which there were declines in catches of pelagic, reef and lagoon fish, particularly in Galle and Hambantota.
It is not always entirely clear from the results whether the changes were thought to be effects on populations of the target species, or whether they were related to reduced effort after boats and gear were lost. In the beach seine and crustacean fisheries in Galle and Hambantota it was clear that fisherfolk thought that there were no changes in the stocks and that catches were down because of debris hampering fishing or the lack of gear. Interestingly, for lagoon fisheries, people in two districts reported a temporary increase in shrimps which was then followed by a decline. This compares with the findings in Aceh (Aceh Jaya) where a similar increase in prawns was observed in areas where mangroves had been removed. In Galle and Hambantota, participants reported a serious oversupply of boats and in some cases, replacements of traditional boats with motorized craft. Impacts on fisheries ecosystems included effects in all major habitats, ranging from erosion, loss of mangroves, problems with debris and pollution and changes in lagoons brought on by altered physical conditions (water flow, sedimentation, opening or closing of sand bars).
Galle: The small pelagic fishery shows an influx in FRP boats from the 1990s, with
non-motorized traditional craft (Oru) being in use before and since that time (Figure 10).
Catches by both types of
boat show a steady decline since the 1960s (Oru) and 1990s (FRP). For traditional boats,
catches dropped
from 80 kg/boat/day in the 1960s to 20 kg/boat/day in 2004 and zero in 2005 after all of the boats were
wiped out by the tsunami. In 2006 their catch rates rebounded to about 8 kg/boat/day. For
FRP boats catches
fell from around 65 kg/boat/day to around 12 kg, but there was no change in the trajectory
of this line
resulting from the tsunami. This could be related to the way boats were replaced, as most of the lost
traditional boats were replaced with FRP boats. The medium pelagic fishery saw a decline in
unpowered boats and
a slow increase in ring-net boats, with a gradual increase overall between the 1960s and
2005. In
2006, the number of FRP boats increased dramatically, with more than 1 000 boats added to
the fleet by
2006 (Maldeniya and Jayamanne 2006). At the same time, the catch per boat per year declined
for
unpowered craft and increased for FRP and ring-net boats. After the tsunami, catches by
powered boats
decreased significantly, while those for unpowered boats increased slightly. The beach seine fishery in Galle
showed a decline in catches between the 1990s and 2006, with the trend continuing unchanged
around the time
of the tsunami. Despite the fact that all boats were lost, they were fully replaced in 2005
(Maldeniya
and Jayamanne 2006). Data on lagoon finfish and shrimp fisheries are limited, but show
decreasing effort
for prawns and increasing effort for finfish. Boats were not seriously affected by the
tsunami but debris in
the lagoons is hindering fishing. There is an indication of declining catches for finfish
and prawns.
Figure 10: PRA results for the small pelagic fishery at Dewata, Gallle, showing changes in numbers of traditional unpowered and FRP boats, and the catch over time. The red line is the tsunami
Hambantota: The long-term trends and responses of fisheries to the tsunami in Hambantota showed similar trends to those seen in Galle. The small pelagic fishery in this district has witnessed a change in boat types from traditional unpowered and then powered boats to FRP boats which were introduced in the 1980s. Many boats were lost to the tsunami, but in 2006 they had been replaced and there was an increase in FRP boats of 49 percent. Catches by all boat types show a declining trend since the 1960s for traditional boats and almost since the time of introduction of FRP boats. Catches to date in 2006 are still low, despite more boats. In medium pelagic fisheries, 28-foot-inboard day boats have been replaced gradually by FRP boats since the 1970s. Most of the FRP boats were lost during the tsunami, but have now been replaced; there are now many more boats than before the tsunami. Over the same period, in Kalametiya, catch rates declined from around 250 kg/boat/day (28-foot boats) and 100 kg/boat/day (FRP boats) in the 1970s to 20 and 10 kg/boat/day by mid-2006. A similar pattern was seen in Mawella where gillnet catches of 1 500 kg/boat/day in 2000 declined to about 250 kg/boat/day in mid-2006. The beach seine fishery has witnessed a decline in catches since the 1960s, with very low catches in 2000. Only one boat remains in operation after all of the others were lost in the tsunami. None of the boats have been replaced and fishing is severely restricted by the debris in shallow waters. The Rekawa Lagoon fishery had a steady increase in the number of boats between the 1960s and 2004. None of the boats were damaged by the tsunami, but the number of boats increased by 44 percent subsequently. Catches of fish and prawns have been declining in the lagoon fishery since the 1960s, a trend which continued after the tsunami (Maldeniya and Jayamanne 2006).
Figure 11: PRA results for the lagoon fishery at Rekawa, Hambantota, showing changes in numbers of traditional unpowered boats (Oru), and catches over time. The red line is the tsunami
Kalutara: The beach seine fishery in Kalutara (catch/boat/day) has been declining since the 1960s dropping from almost 6 000 kg/day to just over 1 000 kg/day (Figure 12). This declined further after the tsunami, probably because of losses of boats and gear.
Maldeniya and Jayamanne (2006) concluded that coastal fisheries had declining catch rates for a long time before the tsunami and were in trouble before it struck. Most of the coastal fisheries resources have been overexploited or exploited to their maximum. Further, productivity may be declining due to damage to the coastal ecosystems and destructive fishing methods in use.
Figure 12: PRA results for the beach seine fishery at Kalutara, showing changes in numbers of boats, nets and the catch over time. The red line is the tsunami
Through the PRA process, followed by national workshops held in Aceh and Sri Lanka (MMAF 2006; NARA 2006), participants identified issues related to tsunami impacts and recommendations for addressing tsunami and non-tsunami impacts on fisheries ecosystems. The most important of these included:
Fisheries
Ecosystems
Workshop participants suggested a range of actions that could be taken to address these
issues. In
Sri Lanka, some of the recommendations centred
on increasing fish production and use of remote
sensing technology and better boat design to increase catch efficiency, while at the same
time promoting
better fisheries management. Other recommendations focused on reducing fuel use through
promoting use
of the sail, maximizing income through value-adding and providing training for alternative
livelihoods, particularly for women. Participants suggested that problems with reduced
access to fishing
grounds would be best addressed through better coordination among agencies (referring to the establishment
of sanctuaries and coastal protection) and better planning.
In Indonesia, participants highlighted a range of actions including better stock assessments, improving livelihoods through better safety, facilities and diversification into post-harvest processing, aquaculture and land-based livelihoods and improving the aid delivery process. They also suggested that weak institutions would need to be strengthened to deal with the complex issues that have arisen since the tsunami, including conflicts among fisherfolk and industry and, in some areas, increased fishing capacity.
In addition to providing a wide range of services to humans (e.g. nutrient cycling, flood control, protection) (Chong 2005), coastal ecosystems provide the critical habitats that support the wide range of fished species found in Aceh and Sri Lanka. Loss or serious damage to these habitats could be expected to lead to declines in resources either in the short or longer term.
Fisheries habitats are here defined as those zones that provide significant ecosystem support to either fished resources or to fisherfolk themselves. In terms of tsunami-affected areas, fisheries habitats include coral reefs and other rocky or soft-sediment nearshore areas, sea-grass areas, coastal lagoons, estuaries and mangroves. Beaches are an integral part of the coastal lagoon systems of Sri Lanka, and in many countries provide sites for fisherfolk to maintain and store boats, clean fish, market their products, service nets and carry out other fishing-related tasks. For the purposes of this study, the review will focus on habitats for fished resources rather than on services provided to fisherfolk.
Most of the work that has been carried out in tsunami-affected areas on habitats of
direct concern
for fisheries resources has centred on coral reefs and is reviewed and summarized by
Wilkinson
et al. (2006). Coral reefs, considered fragile, can be slow to recover and can
provide significant fisheries habitats
and/or livelihoods. In Aceh and Sri Lanka coral reefs would only contribute direct habitat
support for a
small part of the overall marine catches which are more focused on pelagic, trawled and
offshore species.
An initial assessment of damage by the Indonesian Government was that there was 30 percent
damage to
97 250 hectares of coral reef in north Sumatra at a net loss of US$332.4 million. There was, however, little baseline information on the status of coral reefs in the area on which to base
this estimate
(ICRI 2005) and concerns over coral reef damage (LIPI and IMR 2006) are based on general
condition, but
not deviation from pre-tsunami conditions. There were a few cases of spectacular damage,
particularly
near the epicentre on Simeulue Island, with cases of uplift and submergence (Foster
et al. 2006; LIPI 2006). On other reefs there was substantial mechanical damage,
mainly due to debris and sediments washed
off the land. According to ICRI (2005) tsunami damage was additional to considerable prior
damage
from human activities, especially destructive fishing (including fishing with explosives).
A study using data from before and after the tsunami detected no changes in the shallow coral assemblage on Pulau Weh in Aceh (Baird et al. 2005), despite an estimated run-up height of 5 metres at this location (USGS 2005). In this study there was no detected change in shallow water coral assemblages between March 2003 and April 2005, with the exception of one site smothered by sediment. This was supported by the findings of Rudi and Fadli (2005) who also reported generally good reef conditions and attributed degradation of coral reefs at Weh Island to human activities such as illegal fishing. Reef conditions in Aceh varied widely within the province and were clearly correlated with management regimes. Coral cover was high, and the cover of algae and rubble low at Kawasan Wisata and Panglima Laut sites (under management). In contrast, coral cover was low and the cover of algae and rubble was high at open access sites. Baird et al. (2005) and Campbell et al. (2006) described the damage to reefs in Aceh as occasionally spectacular, but surprisingly limited, given the proximity of their sites to the epicentre of the earthquake.
In Sri Lanka, information on damage to coral reefs is limited. Rapid assessments of the impacts on corals put damage due to the tsunami at relatively high levels (NARA et al. 2005; Rajasuriya 2005), describing it as "widespread" (CORDIO and IUCN 2005) and "patchy" (UNEP and MENR 2005). In one location on the southwest coast, zero impacts were recorded for coral reefs, while for most other locations the impacts were reported as medium or high. The greatest impacts were reported from Dutch Bay where reef damage was considered extreme.
According to ICRI (2005) the overall damage to the coral reefs of the region was site dependent and heavily influenced by local environmental conditions such as water depth (shallow reefs most affected), damage to land and coastal morphology (e.g. the presence of channels between islands which focused wave energy). Baird et al. (2005) also found that direct damage in Aceh was dependent on habitat, being largely restricted to corals growing in unconsolidated substrata. The picture from the majority of the other reports from the Indian Ocean (Brown 2005; Comley et al. 2005; Gunn et al. 2005; Satapoomin et al. 2006) is that the damage caused to coral reefs by the earthquake and tsunami was rarely of ecological significance. Even in northern Aceh close to the epicentre, tsunami damage was trivial when compared with that caused by chronic anthropogenic impact.
Site assessments undertaken by NARA staff in Sri Lanka as part of this study, and the opinions of fisherfolk during the PRAs, showed that damage to reef ecosystems did occur, but was site specific in effects (Table 5) (Maldeniya and Jayamanne 2006). Damage to coral reefs was recorded at all three districts surveyed, but Kalutara has already recovered naturally. At Galle and Hambantota, damage ranged from low to extreme, with some areas subject to very localized damage and others, such as Unawatuna damaged over a broad area. Most of the damage reported occurred through smothering by sediments or debris, and the shifting of coral rubble.
The main lessons learned on impacts to coral reefs were:
CORDIO and IUCN have carried out extensive work on damage to mangrove forests, particularly in Sri Lanka, because of their reported mitigation of the effects of the tsunami on human communities. Mangrove forests are considered highly threatened and provide services to humans (Dahdouh-Guebas et al. 2005; Danielsen et al. 2005; IUCN 2005d; Kulkarini 2005), including breeding, spawning, hatching and nursery grounds for marine and pelagic species, and livelihoods for human communities. Further, it is now being debated whether mangroves may have mitigated impacts of the tsunami on human life and property (Kathiresan and Rajendran 2005; Kerr et al. 2006). Answering this question has significance not only for humans and the mangrove habitats themselves, but also for fisheries habitats (coastal lagoons, nearshore areas, estuaries, etc.) that might have been buffered from damage either directly or through decreased land-based pollution. In areas with maximum tsunami intensity, it is thought that little could have prevented catastrophic coastal destruction. Further away, areas with coastal tree vegetation may have been less damaged. Modelling suggests that tree vegetation may shield coastlines by reducing wave amplitude and energy (Massel et al. 1999 in Danielsen et al. 2005) and that 30 trees/100 m2 in a 100-metre-wide belt may reduce the maximum tsunami flow pressure by more than 90 percent (Hiraishi and Harada 2003).
Whilst there is little published information on the effects of the tsunami on mangrove habitats in Indonesia, Wilkinson et al. (2006) reported that in Aceh entire forests were destroyed. In Sri Lanka, IUCN (2005e) investigated damage to mangroves in Batticaloa where the tsunami wave was about 6 metres high at the shore and penetrated up to 1 kilometre inland, across a complex mixed vegetated and settled landscape. This complex environment evidently absorbed and dissipated much tsunami energy so that although coconut palms close to the sea were damaged, the lagoon was affected negligibly.
Sea-grass beds were also largely unaffected. There were cases in which beds of sea-grasses were damaged either in channel areas where currents were concentrated, or in areas smothered by sediments (Wilkinson et al. 2006). In Thailand, less than 5 percent of sea-grass beds were affected and those smothered by sediments or eroded by the currents and waves are expected to recover within a year (ICRI 2005; Phongsuwan and Tun 2005). Damage to sea-grass beds in Sri Lanka was also minor (UNEP and MENR 2005). Localized damage to sea-grasses was greatest in Yao Yai Island in Phang-nga Province of Thailand where 10 percent of the sea-grass areas was destroyed (ICRI 2005).
A few studies have focused on changes in nearshore water quality and characteristics, with most of them reporting little change from pre-tsunami conditions. In some cases reports of elevated nutrients, pollution and turbidity were reported soon after the tsunami, but there was no follow up to determine the longevity of the effects. Only one study was carried out off Aceh, and several off the coast of India. It was not possible to find studies carried out in other affected countries, particularly Sri Lanka.
Soon after the tsunami, general physical and chemical water properties in Aceh were found to be similar to pre-tsunami baseline levels and within national standards for pollution, including faecal coliforms (LIPI 2006). This study does not give details on the variables measured, their locations or values and contradicts some findings of increased sedimentation and turbidity over coral reefs (Baird et al. 2005) and that visible from satellite photos of other nearshore areas (UNEP 2006). In July–August 2005, LIPI and IMR carried out oceanographic studies to find indications of tsunami impacts, including changes in ecosystems and productivity (LIPI and IMR 2006). They examined oceanographic conditions, nutrients, pollution and the chemical properties of seawater. The researchers concluded that there were no indications of anomalous chemical conditions in the areas surveyed and that concentrations of dissolved oxygen, phosphates, nitrates and silicates were normal. They also found that there was little impact through pollution — concentrations met Indonesian standards.
Additional information on possible impacts on water quality comes from India, where several studies were undertaken including water quality sampling and satellite analysis. On the Chennai coast, the Adyar and Cooum rivers are polluted by sewage and are normally closed for most of the year because of accretion across the river mouths. DOD (2005) reported that the tsunami opened them temporarily, flushing polluted waters and sludge into nearshore areas. They anticipated that this may have had a significant but temporary impact on coastal waters and biota. Indicator bacteria (including E. coli, faecal coliforms and Salmonella) normally found within 3 kilometres of the coast, were found 10 kilometres out to sea. A study of impacts on biological resources by Annamalai University (DOD 2005) found effects on water quality in the mouths of estuaries and their backwaters, and in the coastal waters between 5 to 10 kilometres offshore. Nutrient levels, especially nitrogen, increased in several rivers and in the coastal waters 0.5 to 1 kilometre offshore. A phytoplankton bloom (Lauderia borealis) was recorded only in the coastal waters off Chennai and not in any other area investigated. Effects on zooplankton populations were also recorded, but these were patchy. The Regional Research Laboratory (RRL) sampled water quality off Kerala and Tamil Nadu, reporting decreased nutrients, productivity and phytoplankton, effects on fish catches and evidence of the transport of sediments offshore (DOD 2005).
An analysis of Oceansat OCM Data by NRSA, Hyderabad (DOD 2005) revealed that sea surface temperatures (SST) of Andaman and Nicobar coastal waters dropped by around 1 C on the day of the tsunami. NRSA also recorded an increase in turbidity in coastal waters between Chennai and Nellore, along the Andhra and Tamil Nadu coasts and the Andaman Islands. In addition to an increase in suspended sediments, highly turbid waters increased their range from 15 kilometres offshore and 50 metres depth as far as 45 kilometres offshore and 1 000 m depth off the Chennai coast. Impacts on coastal chlorophyll concentration included a threefold increase between 25 and 31 December 2004. Although these effects were reported as temporary, DOD (2005) suggested again that effects could be significant on marine organisms. They did not, however, give any indication of how long the effects on SST and turbidity lasted in the areas observed, or any information on actual impacts on marine organisms. Applied Analysis Inc. (2005) carried out preliminary analyses of ICONOS images acquired three days after the tsunami over Porto Novo, India. They found that inland waters were heavily impacted by suspended minerals, with effects extending approximately two kilometres offshore. At the same time, chlorophyll concentrations were variable inland and elevated in a band about three kilometres offshore. No information was given on the longevity of these effects or an update on their current status.
Beaches, coastal dunes, lagoons, mudflats, soft sediment areas and estuaries play a significant role in fisheries in most of the tsunami-affected countries (Sydnes and Normann 2003; Salagrama 2006). In Sri Lanka, for example, there are 45 major brackish-water lagoons and estuaries, with a total water area of 158 000 hectares; the total area covered by mangrove swamps, mudflats and salt marshes is approximately 71 000 hectares. There has been no estimate of impacts on resources in Sri Lanka's unique beach "Stick Fishery" and the resources fished from the closed coastal lagoons.
There are some anecdotal reports of effects for shallow subtidal areas. In a study of tsunami deposits around Aceh, LIPI (2006) identified a layer of tsunami sediments, between 5 and 22 centimetres thick, in 75 percent of samples in coastal marine habitats. In shallow areas, the deposits comprised sand and pebbles, while in deeper areas silts and muds were recorded. Despite the potential, at least in the short term, for tsunami deposits to smother benthic communities, LIPI (2006) reported that seven months after the tsunami benthic communities showed no clear indications of impact. In India, Salagrama (2006) reported that fisherfolk on the Coromandel Coast complained that the fishing grounds had changed, with an increase in depth at the traditional grounds and changes in water currents and tidal patterns near the shore. They reported that many species, particularly shrimp, had been "relocated" by the tsunami and the fisherfolk had to seek new fishing grounds.
Lagoons were temporarily affected by the tsunami in Sri Lanka in many places, inducing changes in the biota of lagoonal and wetland ecosystems as salt and marine sand had intruded and drainage channels had been changed (IWMI 2005). Observers generally concluded, however, that most lagoons have more or less recovered ecologically since the tsunami, except to the extent that they had accumulated sand, debris and litter (e.g. IUCN 2005e; MENR 2005).
Part of the potential for impact on fisheries resources caused indirectly by the tsunami comes in the form of changes in fishing effort. Changes in fishing effort may operate simultaneously in both directions. An increase in effort may occur if people turn to fishing and/or collecting to meet their immediate needs in times of emergency. Emergency fishing may occur during times of war, famine, displacement and natural disasters. Decreases in fishing effort can and did occur. They are associated with loss of fisherfolk, boats and other fishing infrastructure (wharves, ice plants etc.), and in some cases may be attributable to psychological reasons.
The fishing effort was severely affected by the tsunami in Aceh Province and many of the eastern and southern districts of Sri Lanka. It was estimated that in Aceh around 10 to 12 percent of the fisherfolk in the province were killed by the tsunami, with the greatest losses recorded in those districts closest to the northwest tip (Matthews and Ghofar 2006; NACA et al. 2005; Sykuri and et al. 2005) (Figure 13). Fisherfolk mortality was greatest in Aceh Besar (around 33 percent) and was unexpectedly low on Sabang Island and Simeulue where local topography is thought to have protected harbours and the population in general (Matthews and Ghofar 2006).
In terms of fishing boats, around 50 percent of boats with either an inboard or outboard engine were lost or damaged during the tsunami in Aceh Province. This figure was around 30 percent for sailboats. Matthews and Ghofar (2006) did note some inconsistencies in the Sykuri et al. (2005) data, with considerably more lost boats than the original number in some cases, but the picture is generally clear and damage extends throughout the province (Figure 14).
It has been estimated that around three-quarters of the fishing gear in Aceh's
tsunami-hit areas were lost
or severely damaged by the tsunami (Janssen 2005). This translates to the loss of around 20
000 units
of fishing gear (out of 26 000 recorded in 2003) and an estimated financial loss of US$18
million.
Although Janssen discussed the loss of gear in terms of financial damage, in terms of
capacity for fishing, the
loss/damage to gear may be highly significant because most vessels are equipped with several sets of
nets and other gear, which may be used depending on season, type of fish and fishing method. There is
no information currently on rates of replacement of lost nets, lines and other equipment.
Figure 13: Numbers of fisherfolk lost in Aceh Province, Indonesia
Pie data are derived from Sykuri et al. (March 2005) and show the proportion of fisherfolk lost (red) in each district. Values are based on estimates made during assessments of 78 subdistricts across 12 districts in the province. Values in parentheses after each district name show the number of subdistricts assessed. Data for Banda Aceh and Aceh Utara are added from Matthews and Ghofar (2006). The background map is from HIC and shows affected villages in red.
Figure 14: Summary of losses and damage to fishing boats in Aceh Province, Indonesia
Data are derived from Sykuri et al. (March 2005) and show losses and damage to 3 types of fishing craft. Values are based on estimates made during assessments of 78 subdistricts across 12 districts in the province. Values in parentheses after each district name show the number of subdistricts assessed. Bars are ranked in order of total number of inboard boats per district.
Significant losses of fisheries-related infrastructure were also recorded throughout Aceh Province, including drying facilities, fish aggregating devices, meeting halls, landing sites and piers, ice plants and fuel stations (Sykuri et al. 2005) (Table 6).
In Sri Lanka 4 870 fisherfolk were lost and 136 were still reported as missing in April 2006 (MFAR 2006). Added to this is the displacement of another 60 000 fisherfolk, with over 16 430 homes lost and a further 13 300 damaged (MFAR 2006).
More than 10 973 boats (37 percent) were lost and 4 411 (15 percent) damaged by the tsunami (Ministry of Fisheries estimates of January 2005 in CONSRN 2005b). Data on losses in fishing gear appear to be available only for six of the 14 affected districts with 10 994 units of gear lost. This figure is likely to be a serious underestimate as there are no figures for some of the most severely affected districts.
In Aceh, the Panglima Laut carried out a detailed assessment of the number of boats repaired and replaced in the province (Janssen 2005). They reported around 1 600 boats replaced and 224 repaired by the end of September 2005. They came from an uncoordinated mix of individuals and organizations and focused on 7–11-metre-long boats. Although they were the most commonly used size in Aceh, and many were lost or damaged, they were being replaced preferentially because of their affordable price and simple design (Janssen 2005). The distribution of boats across districts has also been uneven, with the four districts closest to Banda Aceh accounting for 40 percent of boat losses, but receiving 75 percent of all boats distributed or repaired (Janssen 2005). Bireuen, Lhokseumawe, Aceh Barat Daya, Aceh Selatan, Simeulue and Nias have received comparatively little in terms of boat support (BRR 2005). Further, Matthews and Ghofar (2006) reported anecdotal information for Aceh that suggests that around 40 percent of the boats built by NGOs since the tsunami are unsafe and unused. In other cases, donors provided boats, but not engines or gear. The Rehabilitation and Reconstruction NAD-Nias Executing Agency (BRR) estimated that only 600 of the total of 4 000 boats to be provided will have a complete set of gear (Janssen 2005).
Savins and Lee (2005) reported a range of problems with the boats being supplied to Aceh that tended to reduce the capacity for fishing. They reported that boats were being constructed poorly, at the lowest budget, to increase output numbers; they were being distributed to non-fisherfolk, reducing assistance to real fisherfolk and their families.
The major parties involved in fishery rehabilitation in Aceh (DKP, BRR, FAO, ADB and Panglima Laut) are only now focusing on the construction of larger boats. At the community level, a focus on larger vessels is criticized by the Panglima Laut and fisherfolk as many are still waiting for the replacement of the small boats. In 2004, however, a total of 638 boats of 10 metres or more in length were recorded in the Provincial Fisheries Statistics Yearbook. According to the Panglima Laut assessment a total of 802 larger boats (>12 metres) are planned for replacement, which may signal a significant potential for increase in the fishing fleet.
There is little evidence, anecdotal or otherwise, of emergency fishing after the tsunami in either Aceh or Sri Lanka. In Sri Lanka it appears that the price of fish plummeted immediately after the tsunami, despite the decreased supply. According to Mr Leslie Joseph (Fisheries Consultant), people avoided eating marine products for fear that they may have been feeding on corpses. There are no figures on the number of fisherfolk that would have simply suspended fishing activities while they attended to recovery of their families, homes and communities. In terms of fisheries ecosystems, environmental considerations were neglected in Sri Lanka regarding decisions on the location of resettlement camps, new construction and the sourcing of building timber, where there had been losses of forests, including mangroves (UNEP and MENR 2005). There may also be some evidence of recent increases in illegal fishing in Sri Lanka at Rumassala Marine Sanctuary. Fish abundances were found to be similar to surrounding unprotected areas, but recent blast fishing craters were seen (IUCN et al. 2005).
In Kanyakumari, India, Salagrama (2006) reported that the tsunami had engendered a "fear psychosis" among fisherfolk about fishing in the sea, reducing their willingness to go fishing and restricting them to perceived "safer" nearshore waters (see also Miller 2005). One of the fears being faced by fisherfolk related to the well-being of their families while they were away.
Government data suggest that at least 50 percent less fishing effort was expended in Aceh waters after the tsunami, compared with pre-tsunami levels. The greatest losses in fishing boats were of the larger, more powerful craft; this might mean that effort was even lower and that some recovery of normally heavily fished stocks might be expected. A range of factors has, however, been identified that suggests there is still a risk to the sustainability and livelihoods of fisherfolk in the region. The reasons quoted by CONSRN (2005c) and WorldFish (2005) include:
There is now evidence that the number of boats has indeed exceeded pre-tsunami levels in some areas of Aceh and Sri Lanka (see Sections 3 and 5.3 of this study). The additional lessons learned as a result of data collected from landings and fisherfolk at the same time are:
