AN EVALUATION OF THE SUITABILITY OF NONSPECIALIST VOLUNTEER RESEARCHERS FOR CORAL-REEF FISH SURVEYS - MAFIA ISLAND, TANZANIA - A CASE-STUDY

Trials are described for testing and validating the use of non-special ist volunteer divers or visual censusing of reef fish populations. Vol unteers showed significant improvement between two censuses in identif ying 56 species in 30 genera. Thus, after 11 additional dives, the los s of precision compared with an experienced 'control' diver was reduce d from 13% to 0.6%. In the second census there was no loss in consiste ncy caused by the use of groups of divers rather than single divers. E ven in the early stages of training the level of precision was suffici ent to detect changes in composition at the trophic level. Coloured ca nvas strips were used as model 'fish' for estimating lengths underwate r. After three trials divers were able to estimate lengths with an 80% accuracy in relation to the true distribution. Copyright (C) 1996 Els evier Science Limited