Age estimation, growth and maturity of the European hake (Merluccius merluccius (Linnaeus, 1758)) from Iberian Atlantic waters

Difficulties in age estimation for hake (Merluccius merluccius) have hampered the assessment of stocks. Here, we describe new, agreed ageing criteria based on the interpretation of the pattern of otolith growth. Improved estimates of von Bertalanffy growth parameters, and new estimates of maturity ogive parameters and length-weight relationships for European hake from Iberian Atlantic waters are presented. The results came from a study carried out during 1996-1997 and provide the first published account of the main life history traits of Southern stock hake. von Bertalanffy growth parameters of males were Linfinity = 70 cm, K = 0.18 year(-1), and t(0) = -0.97 year, and those of females were Linfinity = 89 cm, K = 0.13 year(-1), and t(0) = -1.15 year. Growth of sexes differed from age 3 onwards, with females being on average larger and heavier than males. The estimated total length (L, cm)-total weight (W, g) relationships were W = 0.0132135L(2.8134246) for males and W = 0.0086471L(2.942563) for females. Spawning took place from December to May with a peak in February. The mean length and age at first maturity were 32.8 cm at 2.5 years for males and 45 cm at 4.4 years for females. Application of new ageing criteria showed that otolith sections may be used to determine ages up to 5 years in a consistent manner. These results indicate that hake of the Southern stock grow at higher rates and mature earlier than previously considered. Summaries of hake's life history parameters from other marine regions are also presented in order to make information that belongs largely to the grey literature available. (C) 2003 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.