Long-lived life history for onaga Etelis coruscans in the Hawaiian Islands

Abstract

Onaga Etelis coruscans is an important component of the commercial deep-water handline fishery in Hawaii and is one of the more valuable species because of its local popularity. This species is part of a management unit called the Deep 7, a data-poor fishery comprising six snapper and one grouper species for which information about age, growth, longevity and maturity is incomplete. Although some life history information is available for onaga, prior estimates of maximum age (~10–20 years) likely suffered from underestimation of age, whereas two recent studies provided estimates that were similar to the work presented here—a refined age reading protocol revealed age estimates up to 55 years. This maximum age estimate and the age reading protocol used on onaga otoliths were validated using bomb radiocarbon dating. Using an otolith reference image age reading protocol that relied on the validated otolith sections, almost all onaga otoliths covering nearly the full body size range were used to generate valid growth parameters that may be sexually dimorphic. An empirical estimate of age at the length at which 50% of individuals reach maturity (L50) is 11 years, and fish near the minimum retention size in Hawaii (1 lb (~0.45kg) or ~30-cm fork length) may be just 2–3 years old.