Scarcity of water in haors: Fishes on the brink of extinction
Haor is considered one of Bangladesh's most productive wetland ecosystems. The haor basin is crucial for fish production both commercially and ecologically and home to a diverse range of finfish, including 143 indigenous and 12 exotic species and various freshwater prawn species.
The haor region is anticipated to have approximately 966,900 hectares of fish habitat, which serve as breeding, nursing, feeding, and overwintering habitats for residents and most freshwater migratory fish species. The total fish production of the Haor region was 108880 MT in the 2018-19 fiscal year, with a productivity of 433 Kg/Ha. Many haor dwellers exclusively depend on haor fisheries in Sylhet, Sungamganj, Habiganj, Moulvibazar, Kishoreganj, and Netrokona districts.
According to the Bengali calendar, the Srabon month of the rainy season is ongoing. During the rainy season, the haor region fills to the brim with water and resembles a big inland sea. However, this year, the reality is entirely different: little rainfall has resulted in lower water levels in the haors. Bangladesh contains roughly 373 haors, all of which are in nearly identical condition. Despite the presence of a limited amount of water in the low depressions, which are referred to as bills, the great majority of haor is still parched or water-scarce.
The Bangladesh Meteorological Department's seasonal outlook and available climate model projections predicted below-normal rainfall for June to September in Bangladesh's Sylhet and Mymensingh divisions, as well as India's Meghalaya. Sylhet is located close to Cherrapunji of Meghalaya (India), which typically receives a high amount of rainfall. The haor region receives water from the Shillong Plateau's catchment slopes in India to the north, and the Tripura Hills in India to the south-east.
Fishermen have already reported low fish catch in the haor areas due to a shortage of water. Due to low water volume, fishermen from Hakaluki Haor, Dekhar Haor, Tanguar Haor, and other haors have reported catching low quantities of fish. They are not familiar with this scenario of haor during this time of year.
Most native fish species regard the rainy season to be their breeding season. The haor region's native fish stock is maintained by a natural recruitment process that takes place both within and outside the haor. Every year, a large number of fingerlings/juveniles scatter to haor habitats and adjacent water bodies after spawning. This boosts the region's fish stock. Rainfall is always considered one of the most crucial variables for fish breeding. The migration of indigenous fish species between the bills, haors, and rivers, on the other hand, contributes significantly to fish breeding. The hydraulic linkage between perennial water sources cannot be assured due to insufficient rainfall. The present state of haor could have an impact on native fish breeding and result in low catch rates in capture fisheries.
Due to climate variability and anthropogenic factors, indigenous fish species, particularly small ones, are on the verge of extinction in the haor region. Since this water persists for a certain period of time, a decrease in water volume in the haor region may considerably contribute to the extinction of these vulnerable indigenous fish species.
This anomalous situation will also have adverse consequences on fishermen's socioeconomic status, as the majority of those who rely on fishing for a living in the haor area have no prior employment experience.
The question of whether this exceptionally low water volume in haor is attributable to climate variability or linked to climate change has arisen as a topic of research. However, not only natural factors but also human actions are to blame for the rapid extinction of native fish species in the haor region. There are no fish pass facilities in the newly constructed dams in the haor region, preventing fish species from migrating safely. Other factors include habitat loss, pesticide use, overexploitation, and water pollution.
Between the 2018-19 and 2017-18 fiscal years, the haor region's fish production increased by 12.11 percent. The current unfavourable situation in the haor region may cause this rate of growth to slow. The government, research organizations, and development organizations should all take this seriously in order to determine the underlying cause of the problem and assess the impact on fish breeding and production.
The writer is a postgraduate researcher, Dept of Aquatic Resource Management, Faculty of Fisheries, Sylhet Agricultural University