Variations in Life History Characteristics of the Deep-Water Giant Ruby Snapper Between the Indian and Pacific Oceans

The giant ruby snapper, Etelis sp., attains the largest size of any lutjanid in the Indo-Pacific and is one of the most valuable species harvested from deep-water fisheries along the continental and insular shelf margins throughout its broad geographic distribution.

Despite this species supporting important commercial, artisanal and subsistence fisheries, quantitative assessments of the status of stocks have been limited by an absence of biological information, unreliable catch and effort statistics, and until recently, misidentification with a cryptic congener.

This study aimed, firstly, to describe and compare the age, growth and reproductive characteristics of Etelis sp. between the eastern Indian and western central Pacific Oceans; and secondly, to provide an age-based assessment of the stock in north-western Australia, the only stock for which available data were sufficient to quantify stock status.

Although the growth of Etelis sp. differed significantly between sexes and oceans, longevity was similar with a maximum age of 56 years recorded in the Pacific Ocean. Spawning of this species occurred over five months during the austral summer to mid-autumn (i.e. December to April) in the Indian Ocean, but was not well defined in the Pacific Ocean. The estimated ages at 50 % maturity for females and males in the Indian Ocean were similar (i.e. 4–5 years), whereas lengths at 50 % maturity differed (L50mat = 527 and 456 mm fork length, FL, respectively), but were consistent with corresponding differences in growth between sexes.

Estimates of the relative female spawning potential ratio for Etelis sp. in north-western Australia suggest the status of this stock remained relatively unchanged from 1997 to 2011, at around 60 % of the unfished level.

This assessment provides an example of the relative sustainable exploitation levels for this stock, and potentially other Eteline snappers that exhibit similar life history characteristics, particularly in locations where monitoring and assessments may be data and/or resource limited.

Wakefield CB, Williams AJ, Fisher EA, Hall NG, Hesp SA, Halafihi T, Kaltavara J, Vourey E, Taylor BM, O'Malley JM, et al. 2020. Variations in life history characteristics of the deep-water giant ruby snapper (Etelis sp.) between the Indian and Pacific Oceans and application of a data-poor assessment. Fisheries Research. 230:105651. https://doi.org/10.1016/j.fishres.2020.105651.