Proceedings of the 11th International Coral Reef Symposium, Ft. Lauderdale, Florida, 7-11 July 2008 Session number 22

Proceedings of the 11th International Coral Reef Symposium, Ft. Lauderdale, Florida, 7-11 July 2008 Session number 22 Reef Fish Spawning Aggregations in the Bay of Bengal: Awareness and Occurrence J. Tamelander*, S. Sattar, S. Campbell, V. Hoon, R. Arthur, E.J.K. Patterson, U. Satapoomin, M. Chandi, A. Rajasuriya and M. Samoilys *IUCN, P.O.Box 13513, Dar es salaam, Tanzania Abstract. Reef fish spawning aggregations are highly vulnerable to over exploitation. Little research has focused on spawning aggregations in the Bay of Bengal. Interview surveys were conducted among fishers in India, Indonesia, Maldives, Sri Lanka and Thailand in order to determine the level of awareness of spawning aggregations, to identify aggregation sites and species, and to assess fishing pressure on and status of spawning aggregations. Results show low awareness of spawning aggregations throughout the region except in the Maldives where fishers relying on visually aided hook-and-line line fishing reported in-water observation. 91 spawning aggregation sites corroborated by several fishers were identified in four atolls in the Maldives, including those of Epinephelus fuscoguttatus, E. lanceolatus, E. polyphekadion, Plectropomus areolatus, P. pessuliferus and Lutjanus bohar. This is the first record of spawning aggregations of P. pessuliferus. The spawning aggregations are fished, and the growing grouper fishery will require a precautionary management approach. Increasing awareness among managers and policy makers as well as fishers of the ecological significance and vulnerability of reef fish spawning aggregations remains a high priority. Key Words: coral reef, reef fish, spawning aggregation, reproduction, Bay of Bengal, South Asia Introduction Many species from several families of reef fish spawn in aggregations, including some groupers, snappers, parrotfish and rabbitfish (Claydon 2004, Cornish 2005). A common definition of a spawning aggregation is a group of conspecific fish gathered for the purpose of spawning with fish densities significantly higher than those found in the area of spawning during the non-reproductive periods (Domeier and Colin 1997, Colin et al., 2003). Domeier and Colin (1997) propose there are two types of spawning aggregations: resident and transient, the former generally occurring within the home range of fish that aggregate frequently and throughout the year. The latter may take place at only a specific time of a month once or several times a year, and fish may migrate hundreds of kilometers to an aggregation site (e.g. Bolden 2000). Transient spawning aggregations may represent up to 100% of a species reproductive output (Domeier and Colin 1997). The larvae from aggregations may travel far before settling out of the plankton to mature. Thus spawning aggregations can supply seed for fish populations over very large areas. As spawning aggregation sites and timings tend to be consistent, they are often known to communities with a long history of and high reliance on fishing. While subsistence fishing of spawning aggregations may be sustainable in the long-term, such as has been the case in parts of the Pacific Ocean (Johannes 1981), they can easily become over exploited (Sadovy and Domeier 2005). Persistent fishing may cause spawning aggregations to cease, leading to dramatic declines in a species population (Sala et al. 2001, Aguilar-Perera 2006). Groupers, many of which aggregate to spawn and are long lived with late maturity, are particularly vulnerable to over-fishing (Sadovy 1996, Dulvy et al 2003). However, with adequate protection, spawning aggregations that have been severely overharvested can recover (Beets and Friedlander 1998). Careful management of reef fish spawning aggregations is thus critical to both the health of fish populations and the coral reef ecosystem, as well as to communities that depend on fishing (Domeier et al 2002, Sadovy and Domeier 2005), and should be, but are rarely, considered in Marine Protected Area (MPA) design (Robinson et al 2008). There is a limited but growing body of scientific literature on reef fish spawning aggregations, and the Society for the Conservation of Reef Fish Aggregations (SCRFA, www.scrfa.org) maintains an online database of spawning aggregations (Cornish 2005, Sadovy et al. 2008). Reef fish spawning aggregations have been documented to some extent in the Western Indian Ocean (Robinson et al. 2004, Samoilys et al. 2006, Robinson et al. 2008) as well as in Indonesia (e.g. Pet et al. 2005), but little published 1043

information exists on reef fish spawning aggregations in South Asia and around the Bay of Bengal, except some detailed studies from one atoll in the Maldives (Sluka 2001 a,b). Even anecdotal information is scarce. Consequently both fisheries and MPA management in the region remains constrained by a shortage of data as well as awareness among management institutions. Many species known to form spawning aggregations elsewhere are important resource species around the Bay of Bengal, including several groupers, snappers and trevallies. For example, the Maldives has a well-developed, widespread and unregulated reef fishery serving the tourist resorts in the country. There is also a specific grouper export fishery which although regulated is in decline (Sattar and Adam 2005). A grouper fishery is developing fast in the Lakshadweep Islands, India (Tamelander and Hoon 2008, Arthur 2008), and is already well established in the Andaman Islands and in Aceh, Indonesia. Many resource species in the Gulf of Mannar are threatened by destructive fishing and overfishing (Bakus et al 2000). estimated catches and catch per unit effort. The reliability of interviewees was subjectively assessed based on responses provided, including knowledge of the local environment and fish species as well as years of experience, and rated high or low. Sites, Time and Sampling Effort Surveys were carried out between March and October 2007, focusing on important reef areas with known reef fisheries in five countries (Fig. 1): Maldives: Baa, Dhaalu, Faafu and Vaavu Atolls (56 interviews) India: Agatti and Minicoy in the Lakshadweep Islands (49 interviews), Mandapam and Keezhakkarai coast in the Gulf of Mannar (63 interviews), and informal discussions in the Andaman Islands; Indonesia: Weh Island in Aceh Province (60 interviews); Sri Lanka: informal discussions with fishers in south western and western reef areas; Thiland: Phuket Island, Phuket Province, and Bulon island group, Satun Province (190 interviews). In view of critical knowledge gaps with respect to fish spawning aggregations in the Bay of Bengal as well as present reef fishery trends, a survey was conducted to identify potential reef fish spawning aggregation locations, species and timings, and determine levels of knowledge of them among fishers. Materials and Methods The study was carried out through interview surveys with fishers. Interviews were conducted by field teams familiar with the target areas and with experience of community based research. Interviewers also received training at a regional workshop prior to the surveys. Key informants in fishing communities were targeted, including fishers using a variety of gears and of varying age and experience. A questionnaire based on guidance from SCRFA (Colin et al 2003) and previous surveys in the Indian Ocean (Robinson et al 2004, Samoilys et al 2006) was used. The questionnaire contained questions on personal information (age, years fishing, gear, areas visited etc.); knowledge of occurrence of reef fish spawning aggregations (have aggregations been observed, what appears to be the reason for aggregating, what are the spatial and temporal characteristics etc.); and what species are known to form spawning aggregations. Pictures, including of fish species and hydrated gonads, were used to accompany the questionnaire. In cases where spawning aggregations were known the interview went on to detail habitat, depth, time (month, lunar phase, time of day), as well as fishing pressure, Fig. 1. Map of the region with target areas marked in red. Data Analysis Raw interview data were compiled and data from respondents with low reliability ranking and respondents not aware of spawning aggregations were removed. Data from reliable respondents was further queried to confirm potential spawning aggregations reported. Spawning aggregations were considered corroborated if the species and site were mentioned by at least two respondents, or if direct or indirect evidence was furbished, such as observation of spawning or reports of prevalence of hydrated gonads in catch at the time of an aggregation. Results Results from the survey are reported here except exact 1044

locations and timings of spawning aggregations, which will not be made public due to the sensitivity of this knowledge. Results will be entered onto the SCRFA online database. Maldives Several spawning aggregations were identified in the Maldives, with 91 reported by 2 or more interviewees, 15 of which were reported by 9 or more, and one site reported by 17. Spawning aggregations were validated by reports of sighting of aggregations underwater, and/or enlarged gonads and release of eggs on capture. Fishers reported fish do not take bait when ready to spawn giving low catches during the first few days of an aggregation.. Spawning aggregations of the following species were confirmed (number of respondents in brackets): Epinephelus fuscoguttatus (53); Epinephelus lanceolatus (11); Epinephelus polyphekadion (4); Plectropomus areolatus (42); Plectropomus pessuliferus (11); Lutjanus bohar (6). Possible spawning aggregations of Plectropomus laevis, Variola louti, and Caranx melampygus were reported by one respondent each. Aggregation depths ranged from several meters to over 50m in E. fuscoguttatus and P. areolatus. E. fuscoguttatus, E. lanceolatus and P. areolatus were reported to aggregate in the 3 rd lunar quarter, Plectropomus pessuliferus during full moon. Aggregations reportedly tended to be largest during the inter-monsoon periods (April-May and November-December). India Fishers at Minicoy and Agatti in the Lakshadweep Islands had no information on reef fish spawning aggregations, although their knowledge of local ecological and environmental conditions is considerable. There were also no indications of spawning aggregations in the near-shore shallow coral areas of the Gulf of Mannar. Fishers reported aggregations of several species 5-10 miles offshore in rocky habitat at depths between 10 and 20m, but while opinions of species, timing, and lunar phase are shared among several fishers from different villages none of the respondents identified spawning as a reason for aggregating. Few interviews were carried out in the Andaman Islands and results are inconclusive. Most fishers were unaware of the phenomenon although there were suggestions of potential spawning aggregations of Plectropomus spp. in South Andaman. Indonesia Awareness of spawning aggregations was low, and a distinction between spawning and normal schooling was not made. However, although not corroborated, possible spawning aggregations of five species were reported from sites on the west, south and east coast of Weh Island at different times, dependent on location and species: Bolbometopon muricatum, Cephalopholis miniata, Variola louti, Cheilinus undulatus, and Caranx lugubris. Sri Lanka Informal discussions with fishers indicated no awareness of spawning aggregations in southern and western Sri Lanka. Thailand Some fishers reported fish aggregations in certain areas and at certain times, but while there was some agreement on aggregation timing, location and species, and while these are typical of spawning aggregations reported elsewhere, none of the interviewees mentioned spawning as the reason for aggregating. Discussion The results of the survey indicate that awareness of fish spawning aggregations among fishers in South Asia is low, with some notable exceptions. Possible reasons for this are manifold; we highlight the following: Few fishing methods involve fishers spending time in the water and directly observing reef fish. This is the case e.g. in Thailand (with the exception of indigenous sea gypsy communities), as well as in Aceh, the Lakshadweep Islands, Gulf of Mannar, and the Andaman Islands, where only some spear fishing is practiced, mainly in near shore and relatively shallow areas targeting octopi, lobster or reef fish. Spear fishing is more widely practiced in the Nicobar group of islands not covered by this survey. In Sri Lanka spear fishing using scuba and targeting groupers is common, but as the fishery is illegal fishers are reluctant to furbish information. Overfishing to a point where aggregations may have ceased, or at least been significantly reduced to densities hard to detect; Relatively low reliance on the demersal reef fish species that spawn in aggregations, as in Sri Lanka, where the Scombridae, Carangidae and Clupeidae make up a large part of fish landings (FAO 2006); Fish and fishing constitute supplements rather than the sole primary source of food and income in many communities particularly on the continental margin; Erosion of traditional knowledge, particularly in Lakshadweep, which in the 1960s and 70s saw a shift from reef fisheries to commercial tuna fishing as part 1045

of a development programme. However, the reef fishery remains important for household consumption and many fishing methods are named after the target species, e.g. Chammam fokkal, fishing for grouper in Agatti (Hoon 2003). The higher knowledge of reef fish spawning aggregations in the Maldives is a likely effect of the very high reliance on fisheries. While the pole and line tuna fishery has been the mainstay of the people over hundreds of years, coral reefs are used extensively for catching bait for the tuna fishery and reef fish have been a significant supplemental food source in many areas. The use of visually aided hook and line fishing for grouper means fishers spend long times in the water observing fish first hand. There was not a large difference in years of experience between fishers aware of spawning aggregations (49 interviewees, average 20 years of experience) and those not aware (seven interviewees, average 18 years of experience). As the Maldives follows the Islamic lunar calendar, fishers are able to report lunar phase very accurately. Most respondents reported physical characteristics as the likely reason for spawning aggregations in a given location. Use of GPS among fishers is low; thus sites are defined by reef features and may in some instances be broad approximate areas, such as comparatively featureless reef slopes or sandy areas. Spawning aggregation depths estimated by fishers were dependent on visibility, and thus approximate. Fishers did not provide detailed information on tide and temperature. The tidal range in the area is modest, less than 1m, and temperatures very stable around 29-30, except in areas of localized upwelling. Species There is little information on spawning aggregations among the species identified in this study in Fishbase (Froese and Pauly 2008), while the SCRFA database includes records of confirmed spawning aggregations for most species reported here, including several records of E. fuscoguttatus, E. polyphekadion, P. areolatus from the Indo-Pacific; one record of E. lanceolatus, from Indonesia; a few records of P. laevis, Cephalopholis miniata and Lutjanus bohar from Papua New Guinea; some records of Cheilinus undulatus from Malaysia and Palau; and one record of Caranx lugubris reported from the Cayman Islands. Three species for which potential spawning aggregations were recorded in this study are currently not included in the SCRFA database: Plectropomus pessuliferus, which is listed as a priority species for conservation due to its limited range, but not reported to form spawning aggregations (Domeier et al 2002). Variola louti, which may form spawning aggregations as indicated by observations from Papua New Guinea, with high densities including gravid females (Hamilton et al. 2005); Caranx melampygus, which is listed as forming spawning aggregations in Palau (Johannes 1981). Aggregation spawning of P. pessuliferus is now confirmed in the Maldives. C. melampygus and V. louti were reported by only one respondent each in the Maldives, with unreliable reports of aggregation spawning of the latter in Aceh, and are thus not confirmed records. Conclusions and Recommendations While relatively limited in geographic scope and resolution, and while providing largely indicative results, this study is the first of its kind in the Bay of Bengal, and provides new information on indigenous knowledge of spawning behavior in high value reef fishes. Importantly, it also provides corroborated records of previously undocumented reef fish spawning aggregations in four atolls in the Maldives, including confirmation of aggregation spawning in one grouper previously not known to form spawning aggregations (P. pessuliferus). The also provide useful information for fisheries management. One of the main threats to high value reef fish populations in the Bay of Bengal is the expanding market for chilled and live reef fish in East and Southeast Asia. A precautionary approach to settings export quotas as well as other restrictions could help prevent the overexploitation of fish spawning aggregations seen in Indonesia (Sadovy and Vincent 2002, Mous et al. 2000). A recent survey of grouper stocks in five atolls in the Maldives (MRC unpubl) confirms the decline in the fishery seen from export data (Sattar and Adam 2005), and fishers also reported reduced catches from spawning aggregations. Surveys in the Lakshadweep have shown that grouper diversity is relatively high and populations are recovering after what appears to be a reduction in abundance after the 1998 coral bleaching event (Arthur unpubl.). The C. undulatus density is representative of reefs with very low fishing pressure (Arthur unpubl., Sadovy et al. 2003). However, with continued demand, groupers, as well as other fish, are increasingly caught for cash income and export. Further study is required to document in more detail spawning aggregations in the Bay of Bengal, at a higher resolution than in this initial survey. Such information is critical for fisheries as well as MPA 1046

management planning. Sensitizing policy makers, managers and fishers regarding reef fish spawning aggregations, their conservation and management, remains a high priority for the region. Acknowledgements The authors would like to thank the field teams and all those who participated in the questionnaire surveys. The financial support from the Ministry for Foreign Affairs of Finland is acknowledged. References Aguilar-Perera A (2006) Disappearance of a Nassau grouper spawning aggregation off the southern Mexican Caribbean coast. Mar Ecol Progr Ser 327: 289-296. Bakus G, Arthur R, Ekaratne S, Jinendradasa SS (2000) India and Sri Lanka. In: McClanahan, T. R., Sheppard, C. R. C., & Obura, D. O., (eds.) Coral Reefs of the Indian Ocean; their ecology and conservation. 295-324 Beets J, Friedlander A (1998) Evaluation of a conservation strategy: a spawning aggregation closure for red hind, Epinephelus guttatus, in the U.S. Virgin Islands. Environ Biol Fishes 55:91-98. 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