Otter ( Lutra lutra L.) numbers and fish productivity in rivers in north-east Scotland
Abstract A method has been developed, using radio-tracking and radionuclide recovery, to estimate numbers of otters Lutra lutra along streams of different sizes in Scotland and the amount of time otters spend in these streams. Linear range sizes varied up to 78 km of stream (80 ha of water) for male...
| Main Authors: | , , , |
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| Format: | Book Part |
| Language: | English |
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Oxford University PressOxford
1993
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1093/oso/9780198540670.003.0009 https://academic.oup.com/book/chapter-pdf/52430206/isbn-9780198540670-book-part-9.pdf |
| Summary: | Abstract A method has been developed, using radio-tracking and radionuclide recovery, to estimate numbers of otters Lutra lutra along streams of different sizes in Scotland and the amount of time otters spend in these streams. Linear range sizes varied up to 78 km of stream (80 ha of water) for males and up to 21 km (34 ha of water) for females. Diet composition and food intake were estimated and compared with electrofishing data on populations of the main prey species, brown trout Salmo trutta and Atlantic salmon S. salar. Eel Anguilla anguilla was less important. Overall, otters appeared to take more young salmon than trout, compared with numbers in the population (18% of salmonid prey was salmon, compared with 6% in the population), and they consumed a high proportion of the total biomass of 1+ fish (fish in their second year of life, or over) and of 1+ fish production (53-67%). |
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