196 research outputs found
Criteria for age determination of anchovy otoliths in Sub-division IXa North: analysis of the rings biometric measures
Problems identification in ageing of otoliths of Anchovy (Engraulis encrasicolus) from Divisions VIIIcb and IXa North
White anglerfish (Lophius piscatorius): weight-length relationships, weight conversion factors and somatic indices from two stocks in north-eastern Atlantic waters (ICES Div. VIIIc-IXa2 and Div. VIIb,c,h,j,k)
Black anglerfish (Lophius budegassa): weight-length relationships, weight conversion factors and condition factor trends from a decade of two stocks, in ICES Div. VIIIc-IXa (northern Iberian Atlantic waters) and in Div. VIIb,c,h,j,k (Celtic Sea, south-western Ireland and Porcupine Bank)
Weight-length relationships, weight conversion factors and condition factor are presented from a decade (2006 to 2015) for both stocks of black anglerfish (Lophius budegassa) in northern Iberian Atlantic waters (ICES Div. VIIIc-IXa) and in Celtic Sea, south-western Ireland and Porcupine Bank (ICES Div. VIIb,c,h,j,k). A total of 2035 and 1263 specimens were sampled respectively in each stock from commercial landings and research surveys. Total length [Lt (cm)], total weight [Wt (g)], “commercial” weight (gutted with liver) [Wgl (g)] and “scientific” weight (gutted without liver) [Wg (g)] were obtained.
The weight-length relationships for the combined sexes were: Lt = 0.020 Wt2.916; Lt = 0.017 Wgl2.929; Lt = 0.017 Wg2.922 in Div. VIIIc-IXa, and Lt = 0.025 Wt2.841; Lt = 0.013 Wgl2.984; Lt = 0.013 Wg2.971 in Div. VIIb,c,h,j,k.
The conversion factors (total weight - gutted weight), useful in fisheries management due to the commercial landings of this species are available in gutted weight, were: Wt = 1.186 Wgl; Wt = 1.236 Wg in Div. VIIIc-IXa, and Wt = 1.187 Wgl; Wt = 1.233 Wg in Div. VIIb,c,h,j,k.
These updated values can be used in the process of the annual assessment of the state of both stocks in the ICES working group.
The evolution of the condition factor over the year, indicator of nutritional status evolution, is also estimated for immature and mature individuals of each sex, showing some seasonal variation.
The results are similar to the previously estimated in other studies
Study of seasonal formation of growth rings in the otoliths of the NEA Mackerel (Scomber scombrus) in ICES Divisions 8c and 9a North
Report of the Age Calibration Exercise Analysis for Anchovy in Division 9a (IBERAS survey 2018)
In November 2018, a new acoustic survey (IBERAS) coordinated by IEO and IPMA was
carried out in order to estimate the strength of sardine and anchovy recruitment in the Atlantic
waters of the Iberian Peninsula (ICES Division 9a) and to map its distribution area. As well as
determine the main biological characteristics of these species in the area.
In January-February 2019, an otolith reading exercise was carried out on the anchovy from the
survey to determine its age, with the objective of calibrating the age readings among the
anchovy readers of the IEO and the IPMA, and estimating the accuracy and discrepancies in the
determination of anchovy age among these readers. As well as, to obtain the age length keys of
the surve
Controls of Multimodal Wave Conditions in a Complex Coastal Setting
Coastal hazards emerge from the combined effect of wave conditions and sea level anomalies associated with storms or low-frequency atmosphere-ocean oscillations. Rigorous characterization of wave climate is limited by the availability of spectral wave observations, the computational cost of dynamical simulations, and the ability to link wave-generating atmospheric patterns with coastal conditions. We present a hybrid statistical-dynamical approach to simulating nearshore wave climate in complex coastal settings, demonstrated in the Southern California Bight, where waves arriving from distant, disparate locations are refracted over complex bathymetry and shadowed by offshore islands. Contributions of wave families and large-scale atmospheric drivers to nearshore wave energy flux are analyzed. Results highlight the variability of influences controlling wave conditions along neighboring coastlines. The universal method demonstrated here can be applied to complex coastal settings worldwide, facilitating analysis of the effects of climate change on nearshore wave climate.This work was funded by the U.S. Geological Survey (USGS) Coastal and Marine Geology Program. The authors thank Jorge Perez, IH Cantabria, for providing the GOW wave hindcast and for assistance with wave spectra, and Sean Vitousek, University of Chicago, for a helpful review. This material is based upon work supported by the U.S. Geological Survey under grant/cooperative agreement GI5AC00426. A. R., J. A. A. A., and F. J. M. acknowledge the support of the Spanish “Ministerio de Economía y Competitividad” under grant BIA2014-59643-R. J. A. A. A. was funded by the Spanish “Ministerio de Educación, Cultura y Deporte” FPU (Formación del Profesorado Universitario) studentship BOE-A-2013-12235. Reanalyses of ocean data are available for research purposes through IH Cantabria (contact [email protected]). Southern California Bight look-up table data are available at https://doi.org/10.1594/PANGAEA.880314. Related Southern California nearshore wave data can be found at http://dx.doi.org/10.5066/F7N29V2V
Report of the Workshop on Age estimation of European anchovy (Engraulis encrasicolus)
Based on the results of a full-scale otolith exchange held in 2014, the Working Group on Biological Parameters (WGBIOP 2015) identified the need for an age reading workshop on European Anchovy otoliths (WKARA2). This workshop (chaired by Andres Uriarte, Spain, Begoña Villamor, Spain and Gualtiero Basilone, Italy), was held in Pasaia, Gui-puzcoa (Spain) from the 28 November to 2 December 2016. Five countries took part in this workshop (Spain, Italy, Croatia, Greece and Tunisia), with a total of 16 participants from 9 laboratories. In total 17 areas/stocks were analysed (4 from the Atlantic area and 13 from Mediterranean Sea)
The aim of this workshop was to review the information on age determination, discuss the results of the previous exchange (2014), review the validation methods existing on these species, clarify the interpretation of annual rings and update the age reading pro-tocol and a reference collection of well-defined otoliths.
Age validation studies, in the Bay of Biscay and preliminary validation studies in Divi-sion 9a, Alboran Sea and Strait of Sicily areas were presented, including a compilation of age validation studies of this species as well in the literature. There are several ar-eas/stocks in which validations of the anchovy annual age determination have not been done yet.
Due to the poor percentage of agreement achieved in the 2014 Exchange (mean agree-ment of 66%; mean CV of 58%), the workshop proceeded with a detailed and joint dis-cussion on the growth patterns shown by otoliths from the different areas to find out the major reasons for discrepancies in age determination among readers. At the same time, the joint discussion allowed a better understanding of the pattern of otolith growth in-crements by areas to improve the guidelines for their interpretation. The discussions on examples among otoliths which generated discrepancies in the age determination led to conclude that there were two major sources of disagreements: a) Divergent otolith inter-pretation: different interpretations of the marks, growth bands and edges in terms of their conformity with the expected growth pattern of the anchovies, seasonal formation of the otolith by ages and most common checks. and b) wrong application of the age allocation Rules: it was evidenced during the workshop that for the birthdate first July (or first June) in some cases the age determination rule was not being correctly applied during the first half of the year (from January to June).
Following the workshop discussions there has been a progressive change in the percep-tion of the growth pattern applicable to these anchovy otoliths in many areas which led to some revisions of the otolith interpretation and assigned ages, by which growth at ages 0 and 1 are far prominent than at older ages and the occurrence of checks became more frequently admitted. Furthermore, there have been evidences that the age determination rules have in some instances been inconsistently applied. All these evidences led to con-clude on the need to review past age determinations. Although this task should be de-layed until running an exchange in 2018 to be sure that all the readers apply the protocol and the current criteria of this workshop coherently, since current criteria would change the otoliths interpretation and the age determination in many areas. In addition, for the Mediterranean regions the convenience of midyear birthdates was put in question in comparison with the simplicity of the conventional birthdates at first of January (as these anchovies are in the northern hemisphere).
As a corollary of the former statements, intercalibration exercises by areas, for the differ-ent countries taking part in the age reading of the same exploited stock, are still required.
Finally, this Workshop adopted a common protocol for all areas in order to standardize the anchovy age assignments and to improve the coherence of the age estimates. An agreed collection of otoliths by areas were produced and upload to the Age Readers Fo-rum
Growth of juvenile white anglerfish (Lophius piscatorius) in the Bay of Biscay using otolith microstructure
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