PINGERS: can be the eyes of blind ganges dolphins (Platanista Gangetica Gangetica, Roxburgh 1801)
The growing need for fish extraction for livelihood is resulting in the by-catch mortality and injury of the aquatic mammals through fishing gear entanglement. It is one of the most significant issue of conservation of Ganges Dolphin. The inability of Ganges dolphins to identify the presence of monofilament gill nets results in entanglement and death due to suffocation. In this study, the interactions of Ganges dolphin with fishing gear (Gill net) by attaching Pingers have been investigated. It was assumed that the proximity zone around the fishing gear is the risk zone for the Ganges dolphin. A visual observation was made in an experimental set up of: Control Net (Without reflectors or Pingers), Net with reflectors (used locally to attract fish), Pinger with frequency and source level lower than what is used by Ganges dolphins (10KHz and 132 decibel) and Pingers with Ganges dolphin frequency (70KHz and 145 decibel). A significant difference in mean sighting distance of Ganges dolphins from different experimental set upss has been estimated. Nearest proximity in control net was <1m with a sighting rate of 1.41 sightings/hr whereas for Dolphin Pingers it was
5 to 10m with a sighting rate of 0.12 sightings/hr. Dolphins seem to avoid fishing gear with active Pingers and hence the experiment was to be carried forward to the next level of estimation for determining whether there was any attraction or change in catch per unit effort (CPUE) of fish or habituation of dolphin. Popularising the efficiency of Pingers among management stakeholders and introducing it to the fisher communities can be the next significant step to conserve the species.
Keywords: Ganges dolphin, echolocation, entanglement, Pingers, reflectors.
Citation: *, ( 2018), PINGERS: can be the eyes of blind ganges dolphins (Platanista Gangetica Gangetica, Roxburgh 1801). Scientific Transactions in Environment and Technovation Journal(STET), 11(4): 169-178
Received: 04/13/2017; Accepted: 04/26/2018;