The Kole Fish Count, conducted on February 2 in connection with World Wetland Day across the Kole wetlands of central Kerala, recorded 82 aquatic species. These include 71 fish species (18 species of brackish water fish and 53 species of freshwater fish), five shrimp species, four crab and two mollusc species.
The participatory assessment, in which scientists, students and nature enthusiasts from the Kerala University of Fisheries and Ocean Studies, the Kerala Agricultural University’s College of Forestry and the Kole Birders Collective participated, covered the entire expanse of Kole habitats distributed across Thrissur and Malappuram districts. Among the major Kole regions, Ponnani had a higher diversity than Thrissur.
Maranchery in Ponnani Kole had the highest diversity (45 species) followed by Uppungal (also in Ponnani Kole) and Enamavu (Thrissur Kole) with 34 species each.
With just 18 species, Adat (Thrissur Kole) recorded the lowest diversity.
Some of the most common species encountered during the survey include the orange chromide (known as pallathi in Malayalam), the dwarf pufferfish, Malabar leaf fish, and pearl spot or karimeen .
However, the teams also came across six non-native fish species, raising concerns on the sustainability of the fishery and aquaculture practices being followed in the Kole and vicinity.
The presence of six species of non-native fish in the Kole is of significant concern as these have the potential to compete with, and outnumber native species, said Rajeev Raghavan, assistant professor at KUFOS and the South Asia Coordinator of the IUCN’s Freshwater Fish Specialist Group.
“Particularly alarming is the frequent catches of the Amazonian sucker catfish from various parts of the Kole,” he added.
The government needs to take immediate action to prevent illegal fishing practices carried out during the annual harvest of auctioned waterbodies that are part of the Kole wetlands, noted M. K. Sajeevan, Head, Department of Fisheries Resource Management, KUFOS.
In addition to aquatic biodiversity, the teams also collected samples to assess the health of the ecosystem through evaluation of key water quality parameters, results of which will be released soon.