Resumen del producto

The whale shark is the world’s largest filter feeding shark and holds international protection as an endangered species. It is known to form seasonal aggregations that are often linked to productivity events such as mass fish spawning or blooms of zooplanktonic organisms. The aim of this study was to investigate whether or not whale shark foraging behaviours are related to the density or concentration of available prey items. Zooplankton samples were obtained between October 2016 and March 2017 both in the presence (n = 12) and absence (n = 32) of foraging whale sharks. Results indicated that zooplankton biovolume was significantly greater (W = 99, p < 0.05) when sharks were observed feeding, compared to samples were sharks were not feeding. Composition of taxonomic groups revealed the dominance of copepods and chaetognaths. in the presence of feeding whale sharks was 2.3 times greater than in the absence of feeding whale sharks, although it was not significantly different (W = 132, p > 0.05). We found there to be no significant differences in the mean number of copepods (W = 121, p > 0.05), chaetognaths (W = 134, p > 0.05), euphasiids (W = 201, p > 0.05) and decapods (W = 143, p > 0.05), between the presence and absence of feeding. In conclusion, we report that whale sharks feeding behaviours are highly related to the densities of available prey and the species may potentially target dense patches of both copepods and chaetognaths species to fulfil their dietary requirements.

Palabras clave: Whale shark; Zooplankton communities; ecology; Feeding behaviour

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