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Detected a family nucleus of otters in the river Ripoll

28 Apr 2021
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During the investigations, four specimens of this mammal have been identified in an area where until now there was no evidence of its establishment.

In the context of the " Otter monitoring and study project in the Besòs and Tordera basins", which are being carried out by the RIVUS Observatory , within the RIVUS Foundation , and the Barcelona Zoo Foundation , the presence of a new family nucleus of otters in the Ripoll river, which adds to the first case of reproduction in the basin detected last year in another important tributary of the Besòs. The RIVUS Observatory is coordinated by ICTA-UAB researchers.

The first indications of the new breeding territory were obtained by monitoring the species last autumn. “I was surprised by the great otter activity in this sector of Ripoll. Finding a number of excrements above a certain threshold in a section is usually indicative of the presence of a family group, as families score three times more and have less mobility " , explains Arnau Tolrà , biogeographer and researcher responsible for this line of follow-up.

Upon detection of this fact, some phototrapping cameras were installed in the area, which have finally recorded a female with a brood, about 7 or 9 months, as well as at least one adult male and a solitary female. . It would therefore be a minimum of four otters away from the main core. "This is excellent news that reaffirms the establishment of the otter in the Besòs basin, since with only one breeding female the viability of its population was too subject to the entry of individuals from external basins" , nuance Tolrà. " The new breeding area meets all the requirements for the species we are assessing, including an optimal river habitat structure, food abundance and tranquility," he adds.

Remember that during the last two years (2019 and 2020 in La Tordera and 2020 also in Besòs) the most awaited milestone has been reached: otters have reproduced in both basins for the first time after their local extinction at the end of the last century (see news) . In total, five family groups have been identified in the Tordera basin and, with this latest finding, two in the Besòs basin. The current population is approximately 14 otters in the Besòs basin and at least 20 in the Tordera.

One of the main objectives of this monitoring project - which also has the support of the Besòs Tordera Consortium and the ICTA-UAB and the sponsorship of Grifols and Freudenberg - is to establish conservation measures that allow the protection of the species and of its entire ecological community. The results will allow the integration of new ecological criteria in the management of the river environment.