Age estimation, growth and maturity of the Argentine hake (Merluccius hubbsi Marini, 1933) along the northernmost limit of its distribution in the south-western Atlantic

ABSTRACT

Age, growth and length-at-maturity of the Argentine hake (Merluccius hubbsi) were studied in the northernmost limit of the species distribution in the south-western Atlantic. A total of 351 otoliths and information from 1610 specimens sampled from the industrial double-rig trawl landings between May 2013 and April 2014 were used. Age and growth were estimated by counting and measuring increments in sectioned sagittae otoliths, and length at maturity was estimated based on macroscopic gonadal analysis. For both sexes, hepatosomatic index and condition index increased mainly during spring, reaching a maximum at the end of summer before the subsequent spawning season began. Gonadosomatic index was highest in April, believed to correspond with peak spawning. The annual periodicity of alternate opaque and translucent zones was validated by marginal increment analysis. Growth curves were fitted to back-calculated size at age by fitting the three-parameters von Bertalanffy growth function. The maximum age was 5 years in fish of either sex. Females attained larger sizes than males. The parameters of the von Bertalanffy growth equations were: L∞ = 533 mm, k = 0.231 year⁻¹ and t₀ = −0.935 year for females; L∞ = 394 mm, k = 0.405 year⁻¹ and t₀ = −0.463 year for males. The mean length and age at first maturity was 273 mm at 1.9 years for males and 274 mm at 2.0 years for females.

SUBJECT EDITOR:

• Audrey Geffen

KEYWORDS:

• Growth
• length-at-maturity
• south-western Atlantic
• length-at-age
• Merluccius hubbsi

Acknowledgements

Research grants from Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro – FAPERJ are acknowledged (Costa, PAS, grant E-26/111.578/2014; Vieira, JMS, grant 200.989/2016). We would like to thank the vessels' owners for providing detailed data on the industrial double-rig fishery locations from the Brazilian National Programme of Monitoring Fishing Vessels by Satellite – PREPS and anonymous referees for their critical reviews and suggested changes to the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro – FAPERJ [Costa, PAS, grant E-26/111.578/2014,Vieira, JMS, grant 200.989/2016].