Ecology and niche specialization of two bonefish species in Hawai‘i

Bonefishes are a cryptic species complex that are a prized sportfish in many places around the world. In Hawai‘i they have a long history of use and today have important recreational, and cultural value. In the early 1980s, two distinct species of bonefishes were determined to inhabit Hawaiian waters (Albula glossodonta “round jaw”, and A. virgata “sharp jaw”). Little is known about the life histories of these two species, hindering population assessments and relevant fisheries management guidelines. In addition, no ecological studies have been conducted to examine interactions or separation between these species. This research assesses how differences in size, abundance, diet, growth, reproduction, and habitat preference of the two bonefish species in Hawai‘i can explain the coexistence and persistence of these two closely related species. Differences in size structure, growth rates, and spawning patterns for each species provides species-specific life history information that differentiates them ecologically and is useful for population assessments and in developing species-specific management strategies. We found that the wide-ranging species, A. glossodonta had a larger mean size, length at a given weight, and size at maturity than the endemic, A. virgata. We found differences in prey preferences between the two species that support our hypothesis that differences in jaw morphologies and habitat preferences translate to dissimilarities in diet. This study contributes to our knowledge about these species and provides an example of niche specialization in two closely related and cohabiting species.