Abstract

Growth shapes the life history of fishes. Establishing appropriate aging procedures and selecting representative growth models are important steps in developing stock assessments. Flyingfishes (Exocoetidae) have ecological, economic, and cultural importance to many coastal countries including Taiwan. There are 29 species of flyingfishes found in the Kuroshio Current off Taiwan and adjacent waters, comprising 56% of the flyingfishes taxa recorded worldwide. Among the six dominant species in Taiwan, four are of special importance. This study reviews aging data of these four species, documents major points of the aging methods to address three aging issues identified in the literature, and applies multi-model inference to estimate sex-combined and sex-specific growth parameters for each species. The candidate growth models examined included von Bertalanffy, Gompertz, Logistic, and Richards models, and the resulting optimal model tended to be the von Bertalanffy model for sex-combined data and Gompertz and von Bertalanffy models for sex-specific cases. The study also estimates hatch dates from size data collected from 2008 to 2017; the results suggest that the four flyingfishes have two spawning seasons per year. Length-weight relationships are also estimated for each species. Finally, the study combines the optimal growth estimates from this study with estimates for all flyingfishes published globally, and statistically classifies the estimates into clusters by hierarchical clustering analysis of logged growth parameters. The results demonstrate that aging materials substantially affect growth parameter estimates. This is the first study to estimate growth parameters of flyingfishes with multiple model consideration. This study provides advice for aging flyingfishes based on the three aging issues and the classification analysis, including a recommendation of using the asterisci for aging flyingfishes to avoid complex otolith processing procedures, which could help researchers from coastal countries to obtain accurate growth parameters for many flyingfishes.

Highlights

  • Growth and reproduction are the most important factors that act to increase fish biomass (King, 2007)

  • Since hatching experiments were only for bony flyingfish (BNY) and greater spotted flyingfish (GSP), the present study examined the counts of asterisci and lapilli of the four species and performed simple linear regressions on the data to determine the expected number of pre-asteriscus days

  • Since we found that the best growth model for each species in this study was von Bertalanffy growth model (VBGM), growth parameters of VBGM for the four species in this study were compiled into the global estimates table (39 estimates in total) for classification analysis

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Summary

Introduction

Growth and reproduction are the most important factors that act to increase fish biomass (King, 2007). Inappropriate or uncertain age estimation or growth parameters can lead to misleading perceptions of population condition, cohort strength (recruitment), and the level of fishing mortality (Campana, 2001; Maunder and Piner, 2015) It can affect the estimation of natural mortality and the mean age at maturity ( et al, 2015; Farley et al, 2017; McKechnie et al, 2017), and affect the reliability of scientific advice on stock status and related management measures (Eero et al, 2015; Hüssy et al, 2016; McKechnie et al, 2017). The first three issues (referred to as the three aging issues hereafter) should be considered when performing aging studies on pelagic fish species

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