Ashtamudi Fish Count 2022

About AFC 2022

The first fish census of Ashtamudi lake was organized jointly by Ashoka Trust for Research in Ecology and the Environment (ATREE), Department of Aquatic Biology and Fisheries, University of Kerala, and Department of Fisheries, Government of Kerala on 8th and 9th of March 2022. Selected student volunteers, experts, and fisher folks participated in the census. The training program on 8th March 2022 was inaugurated by Dr Arun S. Nair IAS (Sub Collector, Kollam).

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Dr. Arun S Nair , Assistant Collector, Kollam inaugurating  AFC 2022

Orientation for students and fish experts were given by Anu Radhakrishnan, Senior Program Officer ATREE-CERC. The sampling sites, sampling size and  parameters to be noted were detailed in this lecture. All participants were grouped into 3 for sampling sites named Ashramam, Western and Mandro island respectively.

Anu Radhakrishnan , Senior Program Officer, ATREE
giving orientation
lecture for students and fish experts

Sampling sites

The fish count was flagged off at Ashramam by Smt J. Mercykutty Amma, former Minster, fisheries, Government of Kerala on 9th of March. 

All three cruises collected data based on gill net and cast net catch by the fishermen. Along with fish data collection water samples from all sites were also collected for quality study.  A market survey was also done for consolidating the availability and sustenance of economically valuable fishes.  

Result

Thus the far published data on Ashtamudi fish diversity includes 156 species, where else  Ashtamudi Fish Census (AFC) 2022 recorded and collected 51 species. The finalized list may enhance the number of species, as the results of the market survey are being analyzed. One of the salient features of AFC is the decline in species diversity, and increase in the predominance of marine species, even in the freshwater zone, which indicate a decline in the freshwater flow from the Kallada river. The team also recorded two species for the first time from the lake, which included the tripod fish Tricanthus bicaculeatus (local name Muppiri), and Queenfish, Scomberoides lysan (Cheru paara).

The market survey showed the trends in the dominance of mackerel (Ayala) and Trachinotes blochii (Valavode), in the lake, indicating the increasing presence of marine fish in the lake, which could be an interesting aspect to study in relation with the climate change of the oceans. The team recorded decline in the mean size of the commercially valuable fish, including pearl sport (Karimeen) and mud crab (Kaayal Njandu).

Fish diversity was found to be less in polluted zones of the river, indicating the threats of pollution in the system. Urban pollution, solid waste (specifically plastic pollution) have grown significantly in the region, impacting biodiversity. Of late, there is also rapid invasion by the alien Mytella strigata (Charu Mussel) in Ashtamudi Lake, with significant impacts on native populations of Perna viridis (Green mussel) and the dominant clam species, besides impacting the fish breeding sites in the region.

The other threats to the fish diversity recorded from the region include electric fishing, illegal fishing using small-mesh size nets and poison, and siltation are the other threats in the region.

The team forwarded the following suggestions to better manage the rich fish diversity and biodiversity-dependent livelihoods.

1. Regulations to manage the number of Chinese fishing nets and stake nets in the region based on the carrying capacity of the system and population of commercial fishes.

2. Impose minimum legal size restrictions for all commercial species fished from the lake.

3. Publish a comprehensive publication on the fish diversity of the lake and organize regular education and awareness programs highlighting the unique biodiversity of Ashtamudi lake.

4. Considering the increasing encroachments of the watersheds of the lake, the district authorities should prepare spatial planning in the lake and its watershed.

5. Arrange regular desilting of the estuaries and remove dredged deposits scientifically.

6. Considering the survey report that the mangrove areas act as the rich breeding grounds of fish, crabs, and shrimps, launch a mangrove restoration and livelihood enhancement program coupled with responsible tourism, with the help of fisher’s cooperatives and women self-help groups, and community participation.

7. Ashtamudi lake is the only lake in India that supports locally valuable Arrowfin goby (Oxyurichthys tentacularis) (local name: Koozhavali), declare a fish sanctuary in Ashtamudi lake, after conducting a detailed study on its population dynamics.