Robert John Tulloch grew up on the Shetland Islands during WWII. He spent most of his childhood out of doors, watching the birds and animals along the seashore that was just a few hundred yards away from his home. Tulloch was awarded with an Order of the British Empire for his work as a naturalist, and was featured on a number of BBC natural history units. This is one of several books he wrote about the wildlife of the Shetland Islands, and at 48 pages, it's an excellent summary about the river otters there.
Tulloch describes his initial interest in otters, viewing them, their habits, the pressures on their environment, and how you can potentially spot otters along the seashore. There are exceptional color photos from the Shetland Islands (many now available on the web), by Laurie Campbell, R Hare, Bridget Wheeler, and Tulloch himself. He provides resources for getting involved in saving otters, and a summary European otter fact page.
The materials are highly relevant to Shetland, and although the situation with otter preservation is fluid, the book remains an excellent resource. There are lengthier books on otters, covering more species, and with more details, but not as beautiful as this - this book with this combination of photos, personal experience and focus on Shetland really is quite the gem. Dimensions are 8.75" x 9.75", and it's suitable for advanced elementary readers on up.