Acoustic assessment and distribution of the main pelagic fish species in ICES Subdivision 9a South during the ECOCADIZ 2020-07 Spanish survey (August 2020)

The present working document summarises the main results obtained from the ECOCADIZ 2020-07 Spanish (pelagic ecosystem-) acoustic-trawl survey conducted by IEO between 01st and 14th August 2020 in the Portuguese and Spanish shelf waters (20-200 m isobaths) off the Gulf of Cadiz (GoC) onboard the R/V Miguel Oliver. The 21 foreseen acoustic transects were sampled. A total of 26 valid fishing hauls were carried out for echo-trace ground-truthing purposes. Four additional night trawls were conducted to collect anchovy hydrated females (DEPM-adult ad hoc sampling). Chub mackerel was the most frequent captured species in the fishing hauls, followed by mackerel, anchovy, horse mackerel, bogue, sardine, blue jack mackerel and Mediterranean horse mackerel. Round sardinella, longspine snipefish, Atlantic pomfret and transparent goby showed a very low occurrence, whereas the occurrence of boarfish and pearlside was incidental. Chub mackerel, anchovy and sardine showed the highest yields in these hauls. The estimate of total NASC allocated to the “pelagic fish species assemblage” has shown a slight decrease in relation to the historical records in 2018 and 2019, mainly caused by the regional decrease in Spanish waters. However, both total and regional estimates are still above their respective historical averages. Such estimates are the result of the relatively high acoustic contributions of anchovy, sardine (both mainly in Spanish waters), and chub mackerel (in Portuguese waters). GoC anchovy was widely distributed in the surveyed area, showing the highest densities between Cape Santa Maria and Bay of Cadiz. Anchovy acoustic estimates in summer 2020 were of 5153 million fish and 44 877 tones, with the bulk of the population occurring in the Spanish waters. The population was composed by fishes not older than 2 years, with age-0 fish contributing 75% of the total population. The largest (and oldest) fish were distributed in the westernmost waters and the smallest (and youngest) ones concentrated in the surroundings of the Guadalquivir river mouth and adjacent shallow waters. The current biomass estimate becomes in the second historical maximum within the time-series. GoC sardine distributed almost all over the surveyed area (avoiding the Spanish easternmost waters), but was mainly concentrated between west Cape Santa Maria and the Bay of Cadiz, especially in the Spanish central waters of the Gulf, where numerous dense mid-water schools were recorded in the coastal fringe (20-40 m depth). The estimates of sardine abundance and biomass in summer 2020 were 1923 million fish and 50 721 t, estimates close to the historical average, but lower than the values estimated last year and the most recent maxima reached in 2018. Although up to 5-year olds were recorded in the population, age-0 juveniles accounted for 71% of the total numbers, mainly occurring in relatively shallow waters along the coastal fringe comprised between Tinto-Odiel river mouth and the Bay of Cadiz. Chub mackerel was widely distributed in the surveyed area, mainly in the central and western shelf waters, although the highest densities occurred in the western Algarve. A total of 32 854 t and 448 million fish were estimated for Chub mackerel, estimates similar to the most recent ones and very close to the time-series average. Age-0 and age-1 groups were the dominant age groups and mainly occurring in the Portuguese waters. The oldest fish (3-5 years) occurred almost exclusively in Spanish water

Acoustic assessment and distribution of the main pelagic fish species in ICES Subdivision 9a South during the ECOCADIZ-RECLUTAS 2020-10 Spanish survey (October 2020)

The present working document summarises the main results obtained from the ECOCADIZ-RECLUTAS 2020-10 Spanish (pelagic ecosystem-) acoustic-trawl survey conducted by IEO between 02nd and 21st October 2020 in the Portuguese and Spanish shelf waters (20-200 m isobaths) off the Gulf of Cadiz (GoC) onboard the R/V Ramón Margalef. The survey’s main objective is the acoustic assessment of anchovy and sardine juveniles (age 0 fish) in the GoC recruitment areas. The 21 foreseen acoustic transects were sampled. A total of 22 valid fishing hauls were carried out for echo-trace ground-truthing purposes. Chub mackerel, anchovy, mackerel and sardine were the most frequent captured species in the fishing hauls, followed by bogue, horse mackerel, Mediterranean horse mackerel and blue jack mackerel. Boarfish, longspine snipefish and pearlside showed an incidental occurrence in the hauls performed in the surveyed area. Sardine, anchovy, chub mackerel and mackerel showed the highest yields. Total and regional estimates of total NASC allocated to the “pelagic fish species assemblage” in this survey become the historical records in their time-series. Such estimates are the result of the relatively high acoustic contributions of sardine (both in Portuguese and Spanish waters), anchovy (in Spanish waters), and chub mackerel (in Portuguese waters). GoC anchovy was widely distributed in the surveyed area, although higher densities were recorded between east of Cape Santa Maria and Bay of Cadiz. Anchovy acoustic estimates in autumn 2020, 36 070 t and 3197 million fish, showed a decrease in relation to the historical peak recorded the last year, but they were either close (abundance) or even higher (biomass) than the time-series average. The population was composed by fishes not older than 3 years. As usual, the bulk of the population, including juveniles, was located in Spanish waters. Age-0 anchovies accounted for 75% (2385 million) and 58% (21 060 t) of the total estimated abundance and biomass, respectively. Age-0 estimates experienced a similar decreasing trend than the one showed by the whole population in relation to the historical peak recorded the year before, but with values close to the time-series average. GoC sardine experienced a huge increase in autumn 2020, rising up to its time-series maximum and yielding 208 400 t and 5451 million fish, with similar regional contributions to the population and with the juveniles being located in the Spanish coastal waters. Age-6 group was the oldest age group in the population, although the occurrence of fishes older than 4 years was incidental. The population was mainly composed by fishes belonging to the age-0 to age-2 groups. Juvenile sardines (age-0 group) were the dominant group, accounting for 45% and 24% of the total abundance (2454 million) and biomass (49 259 t), respectively. This age-group also recorded its historical maximum in 2020. Chub mackerel estimates were of 22 918 t and 295 million fish, representing a slight decrease compared with the last year, but still above the time-series average. The population was composed by fishes not older than 3 years, with the age-1 group being the dominant one (73%, 216 million, and 75%, 17 082 t, of the total abundance and biomass). Age-0 fish was the second most important age group in the estimated population (17%, 51 million fish, and 12%, 2759 t, of the total abundance and biomass estimates). The bulk of the age-0 (73%) and age-1 groups (74%) was recorded in the Portuguese water

Four spot megrim (Lepidorhombus boscii) weight-length and weight-weight relationships in northern Iberian waters (stock 8.c, 9.a)

Total weight-length, gutted weight-length and total weight-gutted weight relationships were fitted for the Iberian Atlantic stock of four spot megrim (Lepidorhombus boscii) and their temporal variations were analyzed. The large sample size, size range and timeseries available allowed obtaining robust somatic parameters of combined sexes for the total weight-length relationships (a=0.0043, b=3.2008), for the gutted weight-length relationships (a=0.0055, b=3.1139), and the weight conversion factors (1.062). They are considered to best fit the current biometric relationships and most appropriate to be used in the stock assessment of the status of the stock and they contribute to a deeper knowledge of the life history traits of this species

Megrim (Lepidorhombus whiffiagonis) weight-length relationships in the northern Bay of Biscay and Celtic Sea

The weight-length relationships are of a great interest in fish biology, stock assessment and fishery management, by predicting weight from length information and allowing to estimate the stock biomass. Weight-length relationships of megrim (Lepidorhombus whiffiagonis), an economically relevant flatfish species, are studied for two decades (2001 to 2019) in northern Bay of Biscay and Celtic Sea (ICES stock Div. 7.b-k, 8.abd), two important European fishing areas. More than 22000 specimens collected from commercial landings by AZTI and IEO were sampled. Total fish length, total weight and commercial gutted weight were obtained. Four five-year periods (quinquennium) (2000-04; 2005-09; 2010-14; 2015-19) were defined in the studied time-series. Both the large sample size and time-series available, as well as the collaboration between both institutions collecting complementary information from this stock, allowed obtaining robust somatic parameters and analyzing their temporal variations. A weight-length relationship model was fitted and the quinquennium and semester factors, which are of interest biologically and for assessment purposes, and their interactions were significant in the preliminary model. The weight-length relationships, both for total and gutted weight and for the combined sexes of the most recent quinquennium are presented in this work and considered the most suitable to be used in the oncoming annual assessment process of the status of this stock in northern Bay of Biscay and Celtic Sea in ICES

Criterios de Interpretación de la Edad en los Otolitos de la Sardina Atlántica Europea (Sardina pilchardus) (versión 2)

Este manual tiene como objetivo describir los métodos para la determinación de la edad anual de la sardina (Sardina pilchardus), centrándose en los criterios utilizados y estandarizados a nivel europeo para la interpretación de los anillos de crecimiento anual en los otolitos de la sardina atlántica europea. Este manual tiene como finalidad servir de referencia para los lectores de edad de la sardina en los laboratorios del IEO y se basa en los últimos intercambios, talleres y publicaciones sobre la determinación de la edad de la sardina (ICES 2005, 2011, 2019)

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

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02