Interannual early life history variation and larval dispersal of three tropical anguillid eel species recruiting in French Polynesia

Anguilla marmorata, A. megastoma, and A. obscura live in the freshwater habitats of tropical islands spread across the western half of the South Pacific from New Caledonia to French Polynesia, but little is known about their early life histories or spawning areas in the eastern region. Otolith microstructure examinations of 455 glass eels from Moorea (1 river) and Tahiti (2 rivers) in the Society Islands (6 recruitment seasons 2013–2020) found average glass eel ages of 107 ± 12 days (d) (range: 73–145 d) for A. marmorata (N = 250; average total length: 51.5 ± 2.2 mm, 42.4–57.2 mm), 118 ± 11 d (96–150 d) for A. megastoma (N = 80; 52.1 ± 2.2 mm, 46.1–57.8 mm), and 110 ± 11 d (85–143 d) for A. obscura (N = 125; 51.0 ± 1.9 mm, 46.1–56.2 mm). Ages varied among years and sampling periods with wide and narrow ranges observed among species and periods. Hatching dates were August-November dry-season periods and the recruitment season was in the rainy season (November–March), but ages/timings varied in some years (e.g., 2015–2016 El Nino). The young glass eel ages compared to other anguillid glass eel species suggested that Society Island anguillids spawned locally, without long-distance spawning migrations, which was consistent with larval transport simulations in which virtual larvae (v-larvae) dispersed in all directions from Tahiti-Moorea. Back-tracked v-larvae could have originated from many directions, and drift-distances did not provide evidence of much larval-exchange among archipelagos. Future population-genetic, recruitment, and otolith studies at all French Polynesia archipelagos will help understand the spawning and recruitment ecology of central South Pacific anguillid eels.

Life history characteristics of 3 species of anguillid glass eels were studied for the size and age at recruitment to Tahiti and Moorea and for their possible larval dispersal from various types of spawning locations.