Net Gains

Understanding coexistence between Irrawaddy dolphins and fishers in Chilika

In India, the Irrawaddy dolphin is  restricted to Chilika Lake in Orissa.  The dolphin shares a unique relationship with local fishers who believe the dolphin is critical to their fisheries. Our work uses behavioural  and socio-economic approaches to understand this relationship.

  • The Irrawaddy dolphin, an important cultural totem for fishers in Chilika Lagoon

  • Irrawaddy dolphins spend a lot of their time foraging at permanent nets set up by local fishers

  • Irrawaddy dolphins spit water to "herd" fish while feeding

Conflict, cooperation and local fishing traditions

The Irrawaddy dolphin (Orcaella brevirostris) often compete with fishers for fish, occasionally getting trapped in nets as a result. In some instances however, the Irrawaddy dolphin has developed a seemingly mutualistic relationship with fishing communities in the form of cooperative fishing. Detailed reports of this behaviour have been published for the Irrawaddy dolphin population in Myanmar. At Chilika lagoon, presumed co-operation has been observed between fishers and dolphins. Traditional fishers see the Irrawaddy dolphin as linked inextricably with their fishing activities, and talk of a time when they could call out to the dolphins, to drive fish into their nets. 

However, the importance of this mutualism to the behaviour, life and survival of the Irrawaddy dolphin at Chilika lagoon however, remains unclear. The aim of this study was to analyse human-Irrawaddy dolphin interactions with a special focus on how foraging behaviour is affected by fishing in Chilika lagoon. The specific objectives of this study are to study the foraging behaviour of the Irrawaddy dolphin at Chilika lagoon, along with the dependence of the dolphin on co-operative forging with fishermen, to investigate the significance of dolphins to the fishers, and to analyse the attitudes and perceptions of local fishers towards the Irrawaddy dolphin and its conservation.

Chilika 20fisher 20with 20net

Traditional fishers in Chilika fish at fixed nets

Fishing with dolphins

Our work is showing that the benefits that fishers perceive have strong roots in cultural traditions.  Fishers see the dolphin as an important totem, a goddess incarnation sent to them to help them fish.  Behavioural observations showed that dolphins employ a range of feeding techniques in the lagoon including very complex group foraging behaviours.  However, many dolphins dedicate a large part of their time feeding at nets, if not from them.  We have also documented them using a curious 'spitting' behaviour which they use to herd fish towards nets.  Fishers perceive this herding as a form of cooperative fishing and believe it helps boost their catch.  Our observations partially confirm these beliefs - while fish catch does not necessarily increase when dolphins feed at nets, the composition of the catch is markedly different, increasing the economic value of the catch for fishers. When dolphins forage at nets, the catch is dominated by mullets, which, apart from being economically important, is also a fish that local fishers prefer.  Our studies are showing that this cooperative fishing between fishers and dolphins is based on a  complex interplay of behaviour, economics and culture. 

Irrawaddy 20pod

A pod of Irrawaddy dolphins feeding cooperatively





  • Book Chapter
    Narrative from Indian seas: Marine resource use, Ecosystem responses, and the accidents of history.
    Pages 229-248 in G. Cederlöf and M. Rangarajan (editors), 'At Nature's Edge: The Global Present and Long-Term History,' Oxford University Press, New Delhi. 331 pp.
  • Journal Article
    Positive interactions between Irrawaddy dolphins and artisanal fishers in the Chilika Lagoon of eastern India are driven by ecology, socio-economics and culture
    Coralie D'Lima, Helene Marsh, Mark Hamann, Anindya Sinha, Rohan Arthur

    In human-dominated landscapes, interactions and perceptions towards wildlife are influenced by multi- dimensional drivers. Understanding these drivers could prove useful for wildlife conservation. We surveyed the attitudes and perceptions of fishers towards threatened Irrawaddy dolphins (Orcaella brevirostris) at Chilika Lagoon India. To validate the drivers of fisher perceptions, we : (1) observed dolphin foraging behavior at stake nets, and (2) compared catch per unit effort (CPUE) and catch income of fishers from stake nets in the presence and absence of foraging dolphins. We found that fishers were mostly positive towards dolphins, believing that dolphins augmented their fish catch and using culture to express their perceptions. Foraging dolphins were observed spending half their time at stake nets and were associated with significantly higher catch income and CPUE of mullet (Liza sp.), a locally preferred food fish species. Wildlife conservation efforts should use the multidimensional drivers of human–wildlife interactions to involve local stakeholders in management.

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