Factors affecting estimates of size at age and growth in grey triggerfish Balistes capriscus from the northern Gulf of Mexico

Factors affecting estimates of size at age and growth in grey triggerfish Balistes capriscus from the northern Gulf of Mexico

Growth zones in dorsal spines of grey triggerfish Balistes capriscus from the northern Gulf of Mexico were utilized to estimate growth and examine factors that may affect estimates of size at age. Age was estimated from dorsal‐spine sections of 4687 individuals sampled from U.S. waters during 2003–2...

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Bibliographic Details
Published in:Journal of fish biology Vol. 92; no. 2; pp. 386 - 398
Main Authors: Allman, R. J., Patterson, W. F., Fioramonti, C. L., Pacicco, A. E.
Format: Journal Article
Language:English
Published: Oxford, UK Blackwell Publishing Ltd 01-02-2018
Wiley Subscription Services, Inc
Subjects:
Age
Ageing
Balistes capriscus
Computation
dorsal spines
Estimates
Fish
Fisheries
Fork length
gear selectivity
Growth
Males
Mathematical models
Modelling
Recreation
Sex
Sexual dimorphism
sexually dimorphic growth
Stock assessment
von Bertalanffy growth function
Gulf of Mexico
ASW, Gulf of Mexico
dorsal spines
gear selectivity
sexually dimorphic growth
von Bertalanffy growth function
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Summary:Growth zones in dorsal spines of grey triggerfish Balistes capriscus from the northern Gulf of Mexico were utilized to estimate growth and examine factors that may affect estimates of size at age. Age was estimated from dorsal‐spine sections of 4687 individuals sampled from U.S. waters during 2003–2013, including both fishery‐independent (n = 1312) and fishery‐dependent (n = 3375) samples. Ninety‐six per cent (n = 4498) of these sections were deemed suitable for ageing; average per cent error between two independent readers was 10·8%. Fork length (LF) ranged from 65 to 697 mm and age estimates from 0 to 14 years. Both sex and sample source (fishery‐independent v. recreational) significantly affected estimated size at age for 2–6 year‐old fish. Data were pooled between sources to fit sex‐specific von Bertalanffy growth functions. Results for the female model were L∞ = 387 mm LF, k = 0·52 year−1 and t0 = 0·01 year, while for males L∞ = 405 mm LF, k = 0·55 year−1 and t0 = 0·02 year. These results were significantly different between sexes and indicate clear sexual dimorphism. Thus, growth should be modelled separately by sex when examining population parameters or conducting stock assessment modelling. The positive bias in estimates of size at age computed for recreational v. fishery‐independent samples also has clear implications for stock assessment as growth functions computed with fishery‐dependent samples would tend to overestimate stock productivity.
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ISSN:0022-1112
1095-8649
DOI:10.1111/jfb.13518