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Patterns of cohort decline are key demographic traits that provide a unique temporal perspective vital to understanding population dynamics. The discovery of multidecadal lifespans in tropical surgeonfishes in the 1990s created a paradigm shift to the notion that they are highly vulnerable species with low population recovery rates; however, research into the mortality patterns of surgeonfishes (Acanthuridae) has been sparse until recently. Recent studies on this family have demonstrated an unusual (possibly unique), two‐phase pattern of adult catch‐at‐age, whereby there is a population‐level shift from higher‐than‐expected rates of decline early in life to lower‐than‐expected decline rates for the remainder of the lifespan. To examine the geographic and phylogenetic ubiquity of this pattern, we compiled age‐based information from demographic samples of 70 populations of 25 tropical species spanning the Indo‐Central Pacific and Central‐Western Atlantic. Overall, we found that 79% of populations exhibited strong biphasic patterns, including 88% of populations across the Indo‐Central Pacific. By accounting for empirical relationships instead of using linear catch curves or classical assumptions of natural population decay based on lifespan, we demonstrate that surgeonfishes have turnover times that are two to four times faster than previously believed. Faster turnover times may suggest a higher level of sustainability for surgeonfish fisheries throughout the global tropics than previously estimated. [ABSTRACT FROM AUTHOR]

Objective: To determine the spawning seasonality of two highly targeted jacks (Carangidae; Giant Trevally [known in Hawai'i as ulua aukea] Caranx ignobilis and Bluefin Trevally [known in Hawai'i as 'ōmilu] Caranx melampygus) within Hawai'i through a collaborative effort with local fishers. Methods: By working with volunteer fishers, we collected gonad samples for Giant and Bluefin trevally throughout a 15‐month period on four of the main Hawaiian Islands. Spawning seasonality was assessed using histological gonad samples as well as mean monthly gonadosomatic index (GSI). Result: Fishery involvement proved successful in collecting biological samples needed to understand the spawning seasonality of these species. Participants were able to macroscopically identify when females were spawning versus undeveloped following initial instruction from the researchers. Mature female GSI resulted in similar conclusions as histological analyses. Both species had a spawning season between February and September, with peak spawning occurring from May to July. During the spawning months, a semilunar spawning pattern was observed for Giant Trevally with peak GSI occurring shortly before the full moon. Bluefin Trevally had higher variability, with no distinct lunar periodicity. Conclusion: Training fishers to be a part of the scientific process and collect gonad samples created trust in science and interest in learning more about the biology of their catch. By consistently sharing our progress and results through social media we were able to engage and build trust with the greater fishing community. Impact statementThrough the spawning seasons project, fishers were empowered to contribute to science and be part of the scientific process, which in turn can lead to continuing interest and participation in future management solutions that ensure sustainability. Fishers can use the information learned in this study to practice sustainable fishing by allowing fish to spawn before targeting them. By using science to substantiate traditional management practices based upon observed spawning behaviors, the participants were able to reinforce behaviors that celebrate sustainability within the larger fishing community. [ABSTRACT FROM AUTHOR]

This study provides growth rate, longevity and maturity estimates for the two important species of jack in Hawaiʻi: ulua aukea/giant trevally Caranx ignobilis and omilu/bluefin trevally Caranx melampygus. Maximum observed ages for C. ignobilis and C. melampygus were 31 years and 24 years, respectively. Combined sex von Bertalanffy growth parameter values for C. ignobilis and C. melampygus were as follows: L∞ = 1064 mm and K = 0.18 year−1; and L∞ = 718 mm and K = 0.20 year−1, respectively. Female size at maturity was significantly greater than males for both C. ignobilis and C. melampygus. Size and age at maturity for C. ignobilis was 594 mm and 4.4 years for females and 465 mm and 2.8 years for males. Size and age at maturity for C. melampygus was 372 mm and 4.1 years for females and 329 mm and 2.9 years for males. This study provides the first robust demographic data for both of these highly prized and ecologically important predatory species in Hawaiʻi, which can be used for future assessments or management. [ABSTRACT FROM AUTHOR]