Conservation ActionsThere are no ongoing conservation measures for this species mainly due to peace and order crisis around Lake Lanao. This species is under extremely high risk of extinction due to the proliferation and dominance of invasive alien species, Giuris margaritaceus. Hence, it is imperative that an immediate conservation of B. lindog should be implemented.
Location InformationBarbodes lindog is endemic to Lake Lanao, Mindandao, Philippines. Lake Lanao is the largest lake in Mindanao and the second largest lake in the Philippines. The lake is vital to the whole island of Mindanao. Together with its only outlet (Agus River), Lake Lanao is the major source of hydroelectric power, providing the majority of the electricity needs of Mindanao (Escudero 1995, Rosagaron 2001, Naga 2010, UPLB-DENR 2014). It has a surface area of 357 km2, a maximum depth of 112 m, a mean depth of 60.3 m, a replacement time of 6.5 years, and a lake surface altitude of 702 m (Frey 1969). The estimated extent of occurrence (EOO) of this species is 441 km2 and the area of occupancy (AOO) is 358 km2.
Barbodes lindog was caught in enormous quantities in shallow bays of Lake Lanao according to Herre (1924). In 1963-1964, records showed that this species greatly contributed to the commercial fisheries in Lake Lanao (Villaluz 1966 in Sanguila et al. 1975). In August-December 1973 market surveys, it contributed 0.09 MT= 90 kg in five months (approximately 216 kg/yr by ratio and proportion) to the total fish catch in Lake Lanao (Sanguila et al. 1975). For eleven months of market survey conducted almost daily in 1974, its contribution was down to 0.045 MT = 45 kg (approximately 49 kg/yr by ratio and proportion) (Escudero et al. 1980). This translates to over 77% reduction from 1973 to 1974 only. In the succeeding major market surveys conducted almost daily in March -May 1975, June 1976-June 1977, August 1982-July 1983, 1990-91, no single individual of this species was recorded (Escudero et al. 1980, Escudero and Demoral 1983, Escudero 1995). From 1992 until 2007, there were no major biodiversity and fisheries assessments in Lake Lanao. A few students working on biodiversity assessments and feeding biology of fishes in Lake Lanao recorded this species in very small quantities ((Bacarat 2001, Ali 2001, Gimena 2007). In July-October 2008, fish landing surveys with 12 sampling events and market surveys with 13 sampling events recorded only 1.76 kg of this species while limited direct field samplings by paid fishermen did not detect this species (Ismail et al. 2014). This species was found only in Lumbatan on the southern part of Lake Lanao (Ismail et al. 2014). A more recent fish landing monitoring conducted every other day for almost a year in 2016-2017 in major fish landing sites in the northeastern, northwestern, southwestern and southeastern parts of Lake Lanao still failed to find this species (Torres 2018).
In 2008, interviews with local fishermen revealed that majority never caught B. lindog in their lifetime and some claimed they rarely caught it in Lake Lanao (Ismail et al. 2014). In 2016, most key informant interview respondents represented by local fishermen, fish vendors and housewives living around northeastern, northwestern, southwestern and southeastern parts of Lake Lanao affirmed that this species has disappeared already from the lake for many years. Only one fisherman confirmed that this species still exists in Lake Lanao while two fishermen believed that this is possibly extant in the lake (Torres 2018).
Based on catch statistics and local knowledge, the survival of this species is still a possibility as it has been recorded in the past ten years.
This species is mainly threatened by the invasive alien species, Giuris margaritaceus (Eleotridae), a native species in the Philippines but translocated accidentally in Lake Lanao. This invasive species was estimated to have been introduced in the lake in the early 1970s and eventually occupied the entire littoral portion of Lake Lanao (Escudero 1995). Since the early 1980s, it has become the most abundant fish throughout the lake (Escudero and Demoral 1983). Its increasing contribution to the lake fisheries has coincided with the decreasing catch of all other fishes, outnumbering the endemic, native, and other introduced fish species. Its growing abundance has corresponded with the gradual disappearance of endemic cyprinids in Lake Lanao. The gradual decline of the endemic cyprinid species with the proliferation of G. margaritaceus in Lake Lanao was also observed by the majority of the fishermen as revealed in the key informant interviews. Another invasive species that has contributed to the population reduction of B. lindog is Glossogobius giuris (Gobiidae). The pathway of this predator goby to enter Lake Lanao was by unintentional introduction through the stocking program of milkfish (Chanos chanos) aimed to increase fish production in 1960 (Juliano et al. 1989). Both G. margaritaceus and G. giuris fed on fishes (Sanguila et al 1975, Escudero et al. 1980, Escudero and Demoral 1983, Escudero 1995). Giuris margaritaceus was described as a voracious feeder, devouring almost anything and feeding on organisms that usually live in the littoral zone, where endemic cyprinids inhabit (Escudero and Demoral 1983). It fed on fishes at all stages (Escudero and Demoral 1983, Escudero 1995).
Other widespread threats in the Lake Lanao include overexploitation, rampant use of destructive fishing methods, unsustainable fishing practices, extraction of water for industrial, agricultural and domestic uses, illegal logging and pollution (Torres 2018, Metillo and Garcia-Hansel 2016, Ismail et al. 2014, Naga 2010, Guerrero 2001, Rosagaron 2001, Escudero 1995, Kornfield and Carpenter 1984, Escudero et al. 1980, Sanguila et al. 1975).