The second edition of the ‘Kole Fish Count’, a participatory assessment of the aquatic resources of the kole lands (wetlands) of Kerala, spread between Thrissur and Malappuram districts, was carried out on Saturday in connection with the World Wetland Day.
Volunteers comprising scientists, students and nature enthusiasts from the departments of Kerala University of Fisheries and Ocean Studies (KUFOS); the College of Forestry, Kerala Agricultural University and the Kole Birders Collective participated in the assessment.
The team recorded 82 species of aquatic organisms, including 71 fishes (18 species of brackishwater and 53 of freshwater origin), 5 species of shrimp, 4 of crab and 2 of molluscs, which was 34 species more than those recorded in the first edition of the survey in 2018. Higher number of species is attributed to the extended coverage of the kole ecosystem during the 2019 survey, as only the Thrissur kole was studied in 2018.
Of the 85 fish species, six were non-native, raising alarms on the sustainability of the fisheries and aquaculture practices being undertaken in the kole regions. Between the two major regions, Ponnani had higher diversity compared to Thrissur. Maaranchery in Poonani had the highest diversity (45 species) followed by Uppungal (also in Ponnani) and Enamavu (Thrissur) with 34 species. The lowest diversity was observed in Adat (Thrissur) from where 18 species were recorded. Some of the most common species encountered from all regions of the wetland were the Orange Chromide (Pseudetroplus maculatus), the dwarf pufferfish (Carinotetraodon travancoricus), Malabar Leaf fish (Nandus nandus) and the Pearl Spot (Etroplus suratensis).
In addition to aquatic biodiversity, an assessment of the state of ecosystem health through evaluation of key water quality parameters were also carried out.
“The Government needs to take immediate action to prevent illegal fishing practices carried out during the annual harvest of auctioned waterbodies which are part of the wetlands. Research from KUFOS demanded a total ban on the use of pesticide in the ole paddy system”, said KUFOS Fisheries Resource Management department head MK Sajeevan.
“The presence of six species of non-native fish is of significant concern as these have the potential to compete with and outnumber native species. Particularly alarming is the frequent catches of the Amazonian Sucker catfish from various parts of the kole”, said Dr Rajeev Raghavan, KUFOS Assistant Professor and South Asia Coordinator of the IUCN’s Freshwater Fish Specialist Group.
“As far as the general water quality is concerned, observations seem to be quite normal, similar to 2018 survey. Since the last year’s survey revealed high inputs of nutrients and toxic metals like cadmium, we will focus more on to these chemicals in the 2019 edition also and results will be revealed in due course,” said, Dr Anu Gopinath of the KUFOS Aquatic Environment Management department.