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Email the author (Login required) Age and growth of swordfish (Xiphias gladius Linnaeus, 1758) in the southeastern Pacific (December 1994-September 1996)
DOI: https://doi.org/10.3856/vol37-issue1-fulltext-1
Abstract
Swordfish age and growth of were determined in the fishing area of the southeastern Pacific off the Chilean coast by counting and measuring the rings in cross sections of the second spine of the anal fin. The examination of the edge of the sections and the analysis of the marginal increment allowed us to establish the formation of one growth ring per year. The swordfish growth parameters were estimated using back calculated length data proportional to the age, which was obtained from nonlinear regressions for lower jaw-fork length (LJFL) measurements and spine radius at the present and previous ages. Two models were used for these relationships: (i) linear correlation (model I) and (ii) potential correlation (model II). The latter was selected because of its better fit and because the to values in the von Bertalanffy growth equation are closer to the origin. Hotelling’s multivariate test (T2) showed significant differences in growth between males and females; this was corroborated by Chen’s test. The growth parameters in terms of length for males were: asymptotic length (L∞) = 275.1 cm, growth coefficient (K) = 0.1774 year-1, and age at zero length (to) = -2.1076 year. For females, the parameters were: L∞ = 304.7 cm, K = 0.1533 year-1, and to = -2.0571 year. For the growth parameters in terms of weight, only the asymptotic weight (W∞) was estimated using the LJFL vs. total weight relationship. This was 278.7 kg for males and 406.7 kg for females.
