Cetacean News - I T A L Y (fwd)

From: pita admininstrator (pita@www1.wheelock.edu)
Date: Thu Dec 21 2000 - 15:59:56 EST


C e t a c e a n N e w s f r o m I T A L Y

Reported by Sabina Airoldi / Tethys Research Institute

December 2000

__Survival of a Risso¹s dolphin calf entrapped by fishing gear debris

We would like to report a remarkable example of the potential impact on
cetaceans of floating debris such as discarded fishing gear in the
International Ligurian Sea Cetacean Sanctuary.
The event took place in the western Ligurian Sea (43°42¹17N, 007°43¹94E),
where the Tethys Research Institute has been conducting cetacean research
since 1990.
On 26 October 2000, at 11:20 AM, a group of about 50 individuals including 8
calves was sighted 4.5 miles off the Italian coast, at a depth of about
1000m. The dolphins were travelling at 2-3knt, with no steady
directionality.
At 11:35 a calf - associated with an adult - was spotted with a fishing rope
of approximately 2mm diameter around its foresection. The calf was towing
about 20m of rope, which end was wrapped around a floater made of expanded
polystyrene. The size of the buoy - that was recovered and measured later on
- was 23x11x5cm. Professional fishermen operating in the Ligurian Sea
Cetacean Sanctuary routinely use this kind of floaters for their bottom
long-line nets.
At 11:45, by means of the inflatable boat that serves as a dinghy to
research vessel "Gemini Lab", we carefully approached the calf, still
associated with its presumed mother, and we took some pictures and videos.
The mother-calf pair moved much slower than the rest of the group, because
the calf was frequently slowing down.
At 12:10, moving at the same speed of the calf, we managed to remove the
floater. However, we did not dare to cause further stress to the animal by
handling the rope. Following the detachment of the floater, it was difficult
to recognize the calf among all other group members. Therefore, we attempted
to photograph every calf in the group in order to check if some of them was
still entrapped by the rope.
At 13:00 the sea became too wavy and we were forced to stop working with the
inflatable and go back to the motorsailer. We remained with the group until
14:25, but we were unable to approach close enough to make further
observations of the entangled calf.
Two days later, quite close to the position of the previous sighting
(43°38¹74N, 007°29¹38E), we met the same Risso¹s dolphin group and we had a
chance to take more photographs of all group members. By studying the
developed prints we could recognize the calf, associated with the mother, by
a dark mark on its forsection caused by the rope. He was finally free.

Please direct any inquiry to Sabina Airoldi <sabina.airoldi@iol.it>

Photographs of the Risso's dolphin calf can be seen at http://www.tethys.org



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