Effects of exploitation evident in age-based demography of 2 deepwater snappers, the goldeneye jobfish (Pristipomoides flavipinnis) in the Samoa Archipelago and the goldflag jobfish (P. auricilla) in the Mariana Archipelago

O’Malley, J.M., Wakefield, C.B., Oyafuso, Z.S., Nichols, R.S., Taylor, B., Williams, A.J., Sapatu, M. and Marsik, M. (2019) Effects of exploitation evident in age-based demography of 2 deepwater snappers, the goldeneye jobfish (Pristipomoides flavipinnis) in the Samoa Archipelago and the goldflag jobfish (P. auricilla) in the Mariana Archipelago. Fishery Bulletin, 117 (4). pp. 322-336.

Abstract

The paucity of species-specific biological information for most exploited Indo-Pacific deepwa¬ter snappers (Lutjanidae) limits stock assessment options and management strategies. To improve stock assessments, age-based demographics were esti¬mated for 2 deepwater snapper species, the goldeneye jobfish (Pristipomoides flavipinnis) in the Samoa Archipelago and the goldflag jobfish (P. auricilla) in the Mariana Archipelago. Each archi¬pelago has locations where fishing had not occurred for at least 30 years, pro¬viding a rare opportunity to examine the effects of exploitation on the age and size compositions, growth, and mortal¬ity of these species. Overall, age-based data reveal a greater effect of fishing pressure than those based on size. This difference highlights concerns with size-based analyses; when species have protracted asymptotic growth trajecto¬ries, the resulting fishing impacts may not be readily apparent in size-based analyses because size and age become decoupled. This decoupling also con¬founds comparisons of growth among areas with different exploitation levels. Mortality estimates derived from an age-based catch curve for the unfished areas (where total mortality equals natural mortality) were comparable to those produced by using a maximum-age-based natural mortality estimator. The comparison of these methods indi¬cates that the age-based natural mor¬tality estimator is suitable for use in deepwater snapper stock assessments when direct measures of natural mor¬tality are unavailable.

Item Type:	Journal Article
Publisher:	US National Marine Fisheries Services
URI:	http://researchrepository.murdoch.edu.au/id/eprint/57817

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