Chilika Development Authority (CDA) in collaboration with the Underwater Technology Research Center, Institute of Industrial Science, the University of Tokyo, Japan is going to organise an international workshop on “Conservation of the Irrawaddy dolphin with special reference to the underwater acoustic study” from 25th and 26th March 2010, at hotel New Marion, Janpath, Bhubaneswar.More than 100 participants including the overseas participants are likely to participate in the workshop. This would be the first international workshop on Irrawaddy dolphin in India.
The researchers from Tokyo University who developed the customised hydrophones to capture the clicks of the Irrawaddy dolphin of Chilika would be participating and presenting the paper on the technology developed so far. The venue of the workshop is chosen to be Orissa as the customised hydrophones were first put to use in Chilika. The technology is extremely useful for the observation the underwater behaviour of the Irrawaddy dolphin. Looking at the success of the pilot application of the technology it is extended to other countries. The overseas experts and scientists from Indonesia, Thailand, Srilanka and Bangladesh would be presenting papers on the status of the Irrawaddy dolphin in their respective countries. The basic objective of the workshop is to discuss on the issues and progress made so far in the field of research, conservation and management of Irrawaddy dolphin in India and other parts of Asia. A special session would focus on the scope of underwater acoustic study for conservation and management of dolphin. Dr. P.Dhandapani who rediscovered Irrawaddy dolphin in Chiliika after more than 75 years on 3rd December 1985 would be presenting a paper explaining the status of dolphin in Chilika after 25 years. The workshop would be inaugurated on 25th March 2010 at 10.30 AM at Hotel Marion. Background Chilika is the largest brackish water Lake and a Ramsar site, located along the east coast of India. It is identified as one of the most significant hotspots of biodiversity in the region that harbours the largest population of Irrawaddy dolphins (Orcaella brevirostris). The population of Irrawaddy dolphins the species is found only in South and South East Asian waters. The dolphin population of Chilika Lake in India and Songkhla Lake in Thailand are two isolated or partially isolated lake populations.
The scientific information on Irrawaddy dolphins in Chilika and along the coast of India is not complete thus the species is listed as data deficient. Irrawaddy dolphins in Chilika are found in four ecological regions of the lake i.e. Outer channel, Northern sector, Central sector and Southern Sector. The population size based on direct counts using line transect surveys is estimated to be 158 animals. No intentional killing was reported by Annandale (1915) which holds good now as well in the coastal parts of Orissa. Local fishers traditionally protect the dolphins as they consider them friends and co-operative to fishers, as the dolphins drive fish towards their net. Significantly, Chilika Lake contains the most important lake population of Irrawaddy dolphins in South Asia . The main identified threats to the population are from the operation of variety of fishing nets and gears as well as from the operation of the mechanized boats.A research project was initiated by the Chilika Development Authority in 2002 and continuing, to collect information regarding distribution, abundance, threats and causes of mortality for the population along with the local perceptions towards dolphin conservation. Ongoing research throughout the lake has identified hotspots of dolphin distribution by determining current habitat use and trends in abundance and movement patterns.Based on the findings of these projects mitigatory measures have been initiated to decrease threats and increase awareness. A nature trail is being developed by Chilika Development Authority to popularize land-based observation of dolphins in the Outer channel. A dolphin watching protocol has been developed based on how to approach dolphins and to regulate tourist boat traffic during the peak tourist seasons. Orientation programs with boat drivers and boat owners have been carried out for proper management of dolphin watching in the lake. Appropriate signage, to raise awareness and increase local knowledge towards dolphin conservation is developed and installed.
Proposal has been made to regulate detrimental fishing techniques by creation of a task force consisting of people from the Forest, Fishery and Tourism Departments. Active participation and support of the local community, NGOs, government and international agencies are needed to save this population from extinction. To develop a concrete strategy for development of a conservation plan the study of the underwater behaviour of the dolphin is essential. Due to poor visibility the underwater study by diving was ruled out in chilika. Due to these initiatives and efforts the casualty of dolphin in the Lake is reduced significantly from 12 per annum to 5. Dolphins’ communication is based on echolocation. The term echolocation refers to an ability to locate and discriminate objects by projecting high-frequency sound waves and listening for echoes. Sound waves travel through water at a speed of about 1.5 km/sec, which is 4.5 times faster than sound travelling through air. These sound waves bounce off objects in the water and return to the dolphin in the form of an echo. Dolphin emits high frequency “ clicks” when it bounce back from an object , the brain receives the sound waves in the form of nerve impulses, which relay the messages of sound and enable the dolphin to interpret the sound’s meaning. By this complex system of echolocation, odontocetes can determine size, shape, speed, distance, direction, and even some of the internal structure of objects in the water. Irrawaddy dolphins are able to learn and later recognize the echo signatures returned by preferred prey species. So this provides an excellent opportunity to study the underwater behaviour of dolphin is to use the acoustic technology by use of customised hydrophones to capture the clicks. The major challenge was the technology. As each species of dolphin emits different clicks and the capture the click a customised hydrophone needs to be developed. CDA approached the Tokyo University for necessary help. Fortunately Tokyo University agreed to extend the help. It was a huge task. To formalise the study a Memorandum of Understanding (MOU) was signed between Chilika Development Authority and the University of Tokyo, Institute of Industrial Science, Underwater Technology Research Centre, Japan on March 22nd 2006 for a period of two years initially with mutual interest to develop an advanced observation systems for Irrawaddy dolphin, providing advanced technologies, human resources and training of dolphin researchers for undertaking further studies. The team of scientists from Tokyo University visited Chilika in March 2006 and the preliminary study was conducted to capture the clicks with different types of hydrophones.
The WWF India also collaborated in the study. This preliminary study was of great help for developing a customised hydrophone to perfectly capture the clicks of Irrawaddy dolphin. The team deployed the customised array of hydrophones in chilika to capture the clicks of Irrawaddy dolphin in February 2007. The team found that the customised hydrophones could able to capture the clicks successfully. Based on the output, the team have developed a complete device which is an array of 8 hydrophones with an in-situ data capturing system. The device can be deployed in the lake and it can capture the data uninterruptedly. The digital data captured can be use to interpret its underwater behaviour by use of the software developed by Underwater Technology Research Centre, Japan, Tokyo University. This would help to determine the response of the dolphin to the approaching objects like boats and the noise from the boat and other sources. This would help to develop a protocol for dolphin watching. It would also able to determine size, shape, speed, distance, and direction of movement, its migration within the lake and outside the lake through mouth. During the two days long workshop the technology would be discussed threadbare and based on the outcome the wider application of the technology for conservation of the Irrawaddy dolphin in Chilika and other parts of the world would be developed. CDA would also ink a MOU with Tokyo University for next two years during the course of the workshop.
Puri News by Ranjan Kumar Ganguly, Puri