Two years ago, Mats Amundin, senior zoological advisor at Kolmården Wildlife Park, was invited to a workshop in Baia Babitonga in southern Brazil to discuss the Franciscan dolphin, the most threatened whale in South America. It occurs around the coasts from Brazil down to Argentina, but lives an anonymous life because it is extremely difficult to get an eye on. The most common contact for the public is to find dead Franciscan dolphins on the beach – they have usually stuck and drowned in fishing nets and then drifted to shore. In order to determine how serious the threat is for the species, one has to know how many Franciscan dolphins there are. However, the estimations that have been made are very uncertain, as they are almost impossible to count on traditional methods. Therefore, the researchers at the workshop came up to test the new tecnology developed in the SAMBAH project (www.sambah.org) to count the porpoises in the Baltic Sea. It is about saving the echoes of the porpoises by using a large number of click detectors, so called. C-PODs.
The preparations were initiated immediately after the workshop with the ten C-PODs that Mats brought with him, and they have now funded and linked a PhD student, Renan Lopes Paitach, to the project. At the end of November this year, Mats Amundin was back in Baia Babitonga to collaborate with Renan and his supervisor Dr Marta Cremer from the University of Univille for the C-POD count of the small population of Franciscan dolphins found there. In his luggage he had another ten C-PODs, as well as the previously free of charge lent by the Swedish Maritime Authority. Mats Amundin’s travel and subsistence was funded by the German fundraiser Yaqu Pacha (http://yaqupacha.de).
It is not only Franciscan dolphins who risk getting caught in fishing nets, but also the C-PODs. Mats Amundin has therefore developed a protection cage, which allows the fishing nets to pass by without interfering with the C-PODs. It has been tested during the past year and proved to work very well.
Like the Franciscan dolphin, the porpoise is also exposed to extensive by-catches, and in order to solve it, the EU has decided that the fishermen must supply the nets with so-called ” pingers”, sound scarers that keep the porpoises away from the nets. Kolmården has, in collaboration with SLU Aqua in Lysekil, worked on a new type of pinger, which not only keeps the porpoise away from the nets, but also makes it impossible for seals to use them as “food clocks”. Especially in the Baltic Sea, the gray seal is a big problem for the fishermen by taking the fish in the net and often making large holes in them.
If these pingers also work for the Franciscan dolphins, it could be crucial for the continued survival of the species. To investigate this, Mats, together with the Babitonga researchers, made an experiment like the ones made with porpoises in the Kullaberg area in northern Skåne. C-PODs were placed at different distances from such a “seal-proof” pinger. The pingers were automatically switched on and off in 30-hour intervals. The preliminary C-POD data was crystal clear: when the pinger was on, no Franciscan dolphin sound was recorded, but when it was shut of, lots of clicks were saved. The dolphins are going away from the pingers but soon returns when the pingers become silent. The experiment will last for a total of six weeks and if the results stand out, new tests will be carried out on a larger scale in other areas. Further south, the dolphins live alongside South American sea lions, just like gray seals using fishnet as a dining table – so it is also important to use this special pinger that they can not hear.
Baltic Sea porpoises in the SAMBAH project. Learn more here >>