The Tears of the Singers by Melinda Snodgrass (1993, Paperback, Reissue)

This book is set in the Star Trek universe. The main character is Lt. O'Huru who help solve the mystery of the seal-like creatures. There is conservationists theme in the book. The Seal-creatures are hunted because when they are killed they cry tears that turn into gem stones that are very valueable. The role their serve in the galaxy is more important than realized by the hunters. I was entertained with this book.