Many external flipper tags offer a reward for return of information about the tag. This may entice more people to report information about tags that they encounter in the wild. However, if the reward is too large, it may entice people to actively pursue sea turtles (in order to win the award). Some projects offer hats or T-shirts as rewards, while others offer money (e.g. US$5 or US$10). If you decide to offer an award, you should carefully consider the possible ramifications. Also, it is important to realize that the offer of a reward will remain in place as long as the tags are still remaining on the turtles. You should not offer a reward if you anticipate that your project will not continue for the life of the tag. For a more general study on the ethics of rewards and remuneration in research, see this site: http://www.aaanet.org/committees/ethics/bp2.htm