Age determination procedures for benthic fish in Spanish Institute of Oceanography (IEO)

This handbook presents a summary of the age estimation procedures used in the Spanish Institute of Oceanography (IEO) for some of the main commercial benthic species of fish for the Spanish fleet: megrim (Lepidorhombus whiffiagonis), four spot megrim (Lepidorhombus boscii), white anglerfish (Lophius piscatorius), black anglerfish (Lophius budegassa). It provides information about the sampling program, the morphology of hard parts (otoliths and illicia), their extraction, preparation, and the age estimation criteria. A summary of information related to the accuracy, validation and corroboration of age of each species is also presented, as well as that related to the precision, quality control and verification of age

Age determination procedures for pelagic and benthic species from ICES area in Spanish Institute of Oceanography (IEO)

This handbook presents a summary of the age estimation procedures used in Spanish Institute of Oceanography (IEO) for some of the main commercial small and medium pelagic species and benthic species of the Spanish fleet. It provides information about the sampling program, otolith extraction and preparation, and the age estimation criteria. A summary of the information related to the age accuracy, validation and corroboration of each species is also presented, as well as that related to the age precision, quality control and verification

Age determination procedures on small and medium pelagic species in Spanish Institute of Oceanography (IEO)

This handbook presents a summary of the age estimation procedures used in Spanish Institute of Oceanography (IEO) for some of the main commercial small and medium pelagic species of the Spanish fleet: anchovy (Engraulis encrasicolus), sardine (Sardina pichardus), mackerel (Scomber scombrus), chuck mackerel (Scomber colias), horse mackerel (Trachurus trachurus), Mediterranean horse mackerel (Trachurus mediterraneus) and blue whiting (Micromesistius poutassou). It provides information about the sampling program, otolith extraction and preparation, and the age estimation criteria. A summary of the information related to the age accuracy, validation and corroboration of each species is also presented, as well as that related to the age precision, quality control and verification

First attempt to validate the age estimation of chub mackerel (Scomber colias) in the Bay of Biscay using otoliths

The Atlantic chub mackerel (Scomber colias) is a pelagic fish distributed in warm and temperate Atlantic waters and in the Mediterranean Sea that may be considered the southern congener of Atlantic mackerel (S. scombrus), both species overlapping in Iberian waters. Age determination is an essential feature in fish stock assessment to estimate the rates of mortalities and growth. Chub mackerel is not assessed, but its fishery has increased in northern Iberian Atlantic waters (ICES Div. VIIIc and IXa) and fishery advice of this population may be soon required. The increase in the landings may also reflect a shift in distribution further north possibly associated with climatic variation, and could interact with the population dynamics of other species. Therefore, it is important to know, as accurate as possible, the growth pattern of this species. The age estimation criteria of chub mackerel are not still internationally standardized and have never been validated or corroborated in Iberian waters. This work presents the growth pattern in southern Bay of Biscay (ICES Div. VIIIc) based on samples from a whole annual period (2011). An attempt of semi-direct validation of the age estimation of this species in the area is performed, at first time, based on the otolith marginal increment and edge analyses. The consistency of the age interpretation is tested by the regularity of the increments formation and the comparison of the lengths at age obtained from direct otolith reading and those from back-calculation. Finally, the obtained results are compared with those from other areas

Estimation of age and growth of juveniles of two European anglerfishes, Lophius budegassa and L. piscatorius, in the north-eastern Atlantic waters, from otolith microstructure analysis

The two European anglerfish, Lophius budegassa and L. piscatorius are commercially important species in Europe, but our understanding of their basic biology is far from complete, hence the need to investigate its early life history through the analysis of otolith microstructure. Otolith microstructure analysis is an useful tool that provides information for determining important early life history associated with age and growth of juvenile fish, such as hatch dates and settlement dates, and reproductive and recruitment patterns.The otolith microstructure can also provide valuable information on the frequency of the first annual increments formation that can be corroborated by counts of daily increments. Age, growth and hatching patterns of both European anglerfish species are here estimated by using lapilli microstructure analysis. The otolith microstructure of juvenile anglerfish (< 30 cm) captured from bottom trawl surveys in southern Bay of Biscay (ICES Div. VIIIc, IXa) in autumn is fully described. Analysis of the otoliths provided estimates of post-settlement ages, sizes at settlement and juvenile growth rates, enabling the backcalculation of the hatch date. This study represents the first attempt at characterizing the early life history of both European anglerfish, contributing also to corroborate the time and position of its 268 first annulus and thus to help set a more accurate annual age estimation criterion. This is essential for the stock assessment process of these species by using age-structured models, given the problematic of its annual age estimation