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Revista de Biología Tropical ISSN: 0034-7744 ISSN: 2215-2075 Universidad de Costa Rica Serdiati, Novalina; Arfiati, Diana; Widodo, Maheno-Sri; Lelono, Tri- Djoko; Ndobe, Samliok; Mansyur, Kasim; Moore, Abigail-Mary Perspectives on sustainable management of the Poso Lake (Indonesia) endemic ricefish, Oryzias nigrimas (Actinopterygii: Adrianichthyidae) Revista de Biología Tropical, vol. 69, no. 1, 2021, January-March, pp. 139-152 Universidad de Costa Rica DOI: https://doi.org/10.15517/rbt.v69i1.42404 Available in: https://www.redalyc.org/articulo.oa?id=44967852012 How to cite Complete issue Scientific Information System Redalyc More information about this article Network of Scientific Journals from Latin America and the Caribbean, Spain and Journal's webpage in redalyc.org Portugal Project academic non-profit, developed under the open access initiative ISSN Printed: 0034-7744 ISSN digital: 2215-2075 DOI 10.15517/rbt.v69i1.42404 Perspectives on sustainable management of the Poso Lake (Indonesia) endemic ricefish, Oryzias nigrimas (Actinopterygii: Adrianichthyidae) Novalina Serdiati1*, Diana Arfiati2, Maheno Sri Widodo2, Tri Djoko Lelono3, Samliok Ndobe1, Kasim Mansyur1 & Abigail Mary Moore4 1. Aquaculture Study Program, Tadulako University, Palu, Central Sulawesi, Indonesia; [email protected], [email protected], [email protected] 2. Department of Aquatic Resources Management, Brawijaya University, Malang, Indonesia; [email protected], [email protected] 3. Department of Utilization of Fisheries and Marine Resources, Brawijaya University, Malang, Indonesia; [email protected] 4. Postgraduate School, Hasanuddin University, Makassar, South Sulawesi, Indonesia; [email protected] * Correspondence Received 22-VI-2020. Corrected 28-X-2020. Accepted 09-XI-2020. ABSTRACT. Introduction: The endemic fishes of the ancient lakes of Sulawesi are under increasing threat. Objective: To evaluate the data and information available from a holistic management perspective and to formu- late measures to conserve the endemic ricefish Oryzias nigrimas in Poso Lake, Indonesia. Methods: Collection of primary data from three stations around Lake Poso and literature study. Results: Threats to O. nigrimas include habitat degradation and loss, introduced alien species, and exploitation as a locally important food fish. Options to promote sustainable fisheries management include spatial and temporal limitations to minimise catch of gravid or brooding fish. Habitat protection should include measures to minimise impacts from activities which can reduce water quality and disturb or kill aquatic vegetation. Conclusion: Measures to prevent further O. nigrimas population decline are considered urgent and further research is recommended to fill identified knowledge gaps. Ex-situ conservation, including the development of captive breeding, could also contribute to a holistic O. nigrimas conservation strategy. Key words: endemism; lacustrine; Oryziinae; black buntingi; invasive species; light fishing. Serdiati, N., Arfiati, D., Widodo, M.S., Lelono, T.D., Ndobe, S., Mansyur, K., & Moore, A.M. (2021). Perspectives on sustainable management of the Poso Lake (Indonesia) endemic ricefish, Oryzias nigrimas (Actinopterygii: Adrianichthyidae). Revista de Biología Tropical, 69(1), 139-152. DOI 10.15517/rbt.v69i1.42404 Sulawesi Island, the largest landmass in 2006; Meixner et al., 2007; Schubart & Ng, the Wallacea region, is renowned for high 2008; Walter, Hogan, Haffner, & Heath, 2011; levels of endemicity, including aquatic taxa von Rintelen & Cai, 2009; Mokodongan & (Hadiaty, 2018; von Rintelen & Cai, 2009; von Yamahira, 2015; Vaillant, Bock, Haffner, & Rintelen, Stelbrink, Marwoto, & Glaubrecht, Cristescu, 2013; von Rintelen et al., 2014) 2014). The “ancient lakes” of Sulawesi, includ- The ricefishes (Adrianichthyidae) are a ing the Malili Lake complex in South Sulawesi family with 33 recognised (valid) species in and Poso Lake in Central Sulawesi, are espe- 2013 (Kottelat, 2013), a number which has since cially rich in endemic fishes and invertebrates increased to at least 37 (Mandagi, Mokodon- (Meisner, 2001; von Rintelen & Glaubrecht, gan, Tanaka, & Yamahira, 2018), including the Rev. Biol. Trop. (Int. J. Trop. Biol.) • Vol. 69(1): 139-152, March 2021 139 description of two new species from Sulawesi: Least Concern (LC) including the Poso Lake Oryzias soerotoi (Mokodongan, Tanaka, & endemic Xenopoecilus oophorus (synonyms Yamahira, 2014); Oryzias dopingdopingensis Adrianichthys oophorus and Oryzias oopho- (Mandagi et al., 2018). Of these 37 species, 21 rus) (Mokodongan, 2019m) and O. celebensis ricefishes are native to Sulawesi, a recognised (Lumbantobing, 2019a). However, concerns “hotspot” of biodiversity for this fish fam- have been expressed regarding the threats to ily (Parenti, 2008; Mokodongan et al., 2014; and urgent need for conservation of all Sulawe- Hadiaty, 2018; Mandagi et al., 2018). While si endemic freshwater fishes (Parenti, 2011), Oryzias javanicus is widely distributed across including X. oophorus (Gundo, 2010). Southeast Asia (Mokodongan, 2019a), and O. Among the ancient lakes of Sulawesi, celebensis (previously considered endemic to the ichthyofauna of Lake Poso is particularly Sulawesi alone has also been reported from rich in ricefishes with seven endemic species East Timor (Parenti, 2008; Hadiaty, 2018; (Hadiaty, 2018). The taxonomy of ricefishes Lumbantobing, 2019a), the majority (19 spe- at the genus and species levels is a matter of cies or 90.5 %) of the Sulawesi ricefishes are ongoing research (Mokodongan et al., 2018; endemic to one or more of the ancient lakes Parenti, 2008), with several synonyms in cur- and/or certain riverine systems in Sulawesi rent use for some species (e.g. X. oophorus). (Parenti, 2008; Hadiaty, 2018; Mandagi et al., Using the taxonomy according to Kottelat 2018; Lumbantobing, 2019b; Lumbantobing, (2013), the ricefishes recorded in Poso Lake 2019c; Lumbantobing, 2019d; Mokodongan, are: Oryzias nigrimas (Parenti, 2008; Serdiati, 2019b; Mokodongan, 2019c; Mokodongan, Arfiati, Widodo, Lelono, & Gosari, 2019a; 2019d; Mokodongan, 2019e; Mokodongan, Serdiati et al., 2020), O. nebulosus (Parenti & 2019f; Mokodongan, 2019g; Mokodongan, Soeroto, 2004; Serdiati, Arfiati, Widodo, Lelo- 2019h; Mokodongan, 2019i; Mokodongan, no, & Toha, 2019b), O. orthognathus (Parenti 2019j; Mokodongan, 2019k; Mokodongan, & Soeroto, 2004), Xenopoecilus oophorus and 2019l; Mokodongan, 2019m; Mokodongan, X. poptae (Parenti, 2008), Adrianichthys kruy- 2019n; Mokodongan, 2019o; Mokodongan, ti (Parenti, 2008), and A. roseni (Parenti & 2019p; Mokodongan, 2019q). Soeroto, 2004). Species with such restricted natural ranges are intrinsically vulnerable to extinction (Wal- Anthropogenic activities pose many direct ter et al., 2011). The 2019 version of The IUCN and indirect threats to the environment in and Red List of Endangered Species™ (hereafter around Poso Lake (Nursangaji et al., 2014; referred to as the IUCN Red List) provides Mamondol, 2018), Despite their small size, assessments of the conservation status accord- several ricefishes are exploited as food fish ing to the criteria of the International Union for (Gundo, 2010; Parenti & Soeroto, 2004), while the Conservation of Nature (IUCN) for 36 rice- the remainder may well be caught as by- fishes (Family Adrianichthyidae), including all catch in targeted (ricefish) and other fisheries. but one (O. dopingdopingensis) of the 21 rice- Sulawesi ricefishes are also being proposed fishes reported from Sulawesi. One Sulawesi as potential model organisms for research in endemic (O. wolasi) is classed as Data Defi- fields as diverse as the study of evolution, cient (DD), meaning the data available are behavioural, biological and medical research insufficient to assign a conservation status. (Mokodongan & Yamahira, 2015; Mokodon- Globally, half of the assessed ricefishes gan et al., 2018; Sari, Andriani, & Yaqin, 2018; are classed within one of the IUCN Red Hilgers & Schwarzer, 2019; Sutra et al., 2019). List categories indicating a significant risk Seven of the eight ricefish species assessed as of extinction; it is remarkable that 89 % of Near Threatened (NT) in the 2019 IUCN Red these are ricefishes endemic to Sulawesi. A List are endemic to Sulawesi, and three to Lake third of all assessed ricefishes are classed as Poso: O. nebulosus (Mokodongan, 2019g), 140 Rev. Biol. Trop. (Int. J. Trop. Biol.) • Vol. 69(1): 139-152, March 2021 O. orthognathus (Mokodongan, 2019h), and O. of approximately 35.9 km and 15.3 km. The nigrimas (Mokodongan, 2019n). narrow shallow shelf around the shore reaches The purpose of this study was to evaluate depths of around 5-7 m then plunges steeply the Poso endemic ricefish O. nigrimas from to a maximum depth of ≈ 385 m, with a mean a holistic conservation management perspec- depth of 194.7 m and nearly 2m fluctuation in tive. Based on primary survey data combined water level between rainy and dry seasons. with secondary data and information, the study aimed to provide guidance on potential man- Data collection: Primary data were col- agement measures to sustain this species. lected primarily at three survey stations around Poso Lake (Fig. 1) on a monthly basis from May 2017 to April 2018. These sites were MATERIALS AND METHODS selected based on information from local fish- ermen and data from previous surveys. Quan- Field study site: Poso lake (Fig. 1) is titative in situ measurements visibility (m, situated in Poso District, Central Sulawesi