Impact of feeding fish as a tourist attraction on a coral reef invertivorous fish's diet and growth

Tourism in marine environments is growing each year, especially in regions with attractive coastlines. One of the main activities practised by tourists is offering food, normally bread, to fish. This activity can result in negative impacts that are still not fully understood. Such impacts were previously detected among omnivores, but fish at other trophic levels also respond to feeding by humans. The effects of supplementary fish feeding by tourists on the diet of a coral reef predatorial haemulid fish, a common reef fish in many tourist destinations, were analysed. Specimens were sampled from one location in which tourists frequently feed the fish and another in which fish maintain their natural diet, both in a marine protected area. The standard length, total weight, hepatosomatic index, condition factor, starch content, and diet composition of fish from the two locations were compared. Specimens fed by tourists were generally larger than those consuming a natural diet, but weight, hepatosomatic index, and condition factor were not statistically different. Diet composition varied between the two areas, with almost half of the stomach contents from specimens collected in the supplementary feeding area composed of starch. Considering the natural diet of this species, carbohydrate ingestion can interfere with energy accumulation. Additionally, natural prey species were being consumed on a smaller scale. These results shed light on the controversial issue of supplementary fish feeding as a tourist attraction and provide information to help shape effective ecotourism management. In this regard, the offered food volume should be banned in more sensitive environments, reduced in remaining areas and food quality should be controlled to make ecotourism a more sustainable activity globally.