Incidencia y significancia de las estructuras císticas en ovarios de gádidos

Fish regulate egg production by atresia. Sometimes, oocytes are encapsulated in cystic structures that might remain in the ovary for months, altering female reproductive potential in future spawning seasons. Ovaries of Atlantic cod (Gadus morhua, L.) from the Flemish Cap and European hake (Merluccius merluccius, L.) from the Galician Shelf (NW Spain) were analysed from 1999 to 2006. The prevalence and abundance of ovarian cysts were estimated. Cyst prevalence increased with female size and/or age for both species, and decreased with high condition factor in hake. Cyst intensity does not correlate with any analysed factor. The size/age structure of spawning stock biomass and female condition could affect the prevalence of cysts in the ovaries, though it does not seem to affect cyst intensity in the ovary. Further research is needed to determine cyst resorption time and the impact that it has on egg production and consequently on stock reproductive potential.Los peces regulan la producción de huevos a través de la atresia. En ocasiones, los ovocitos son encapsulados en estructuras quísticas que podrían permanecer en el ovario durante meses, alterando el potencial reproductivo de las hembras en estaciones de puesta posteriores. Se tomaron ovarios de bacalao (Gadus morhua, L.) de Flemish Cap y de merluza europea (Merluccius merluccius, L.) de la costa gallega (NO España) entre 1999 y 2006. Se estimó la prevalencia e intensidad de quistes en estos ovarios. En ambas especies la prevalencia de hembras con quistes aumentó con la talla y/o edad y disminuyó al aumentar el factor de condición en el caso de la merluza. La intensidad de quistes no se correlacionó con ninguna de las variables estudiadas. La estructura de talla/edades del stock reproductor y la condición de las hembras podría afectar la prevalencia de hembras con quistes. Son necesarios más estudios para determinar el tiempo de reabsorción de estos quistes y las consecuencias que esto puede tener en la producción de huevos y por tanto en el potencial reproductivo de los stocks

The Use of Daily Growth to Analyze Individual Spawning Dynamics in an Asynchronous Population: The Case of the European Hake from the Southern Stock

Daily growth patterns and their relationship with reproduction was analyzed in the European hake from the Galician Shelf, where it shows a very protracted spawning with three spawning peaks. The daily growth analysis was performed in otoliths of adult females on the transversal section of the sagittae otolith. Daily increments were measured from the border to the nucleus in females until they were discernible. Results show that daily growth of females decreases during the spawning period because they allocate less energy to somatic growth in favor of the production of gametes, with an increase in growth in July. Lastly, daily growth individual trends showed a “spawning pattern” in 28% of medium and large females, suggesting an individual spawning period of one to two months, with 4–5 valleys of narrow daily increments, likely associated to batch release: individual spawning frequency would be 4–5 days. This is the first time that individual spawning frequency in hake is estimated based on individual data. Finally, the spawning pattern is detected only once per year, indicating that a single female participates only in one spawning peak per year, supporting the hypothesis of the existence of two or more spawning components in the stock.Versión del edito

Atlantic Cod Growth History in Flemish Cap Between 1981 and 2016: The Impact of Fishing and Climate on Growth Performance

Flemish Cap cod collapsed in the early 90’s after facing multiple threats due to climate variability and anthropogenic pressures. A master 35-year cod growth chronology was reconstructed in the present study by using sclerochronology techniques. Three additional chronologies were developed to account for the age-dependent effect of maturity and fishing intensity on growth. All chronologies showed that cod growth has decreased over the years and it is currently at the minimum level in the historic of data series. Hierarchical mixed-effects models were applied to the master chronology to identify extrinsic drivers of growth. The master chronology was divided into 3 periods: Premoratorium (1988-1998), Moratorium (1999-2009), and Postmoratorium (2010-2019). Our results showed that drivers of cod growth in the Flemish Cap varied between periods (Premoratorium: bottom temperature and fishing mortality, Moratorium: cod and pandalus abundance, and Postmoratorium: cod abundance and thickness of the cold intermediate layer). Our results suggest that density-dependence processes, food availability, and global warming may be behind the lack of recovery of the Flemish Cap cod stock. The Flemish Cap cod growth chronology shows variations on growth over time and identifies its drivers, having the potential to be included in the NAFO stock assessments or to be used to set dynamic reference points that guarantees the stock sustainability. IntroductionVersión del edito

Growth, age estimation and corroboration of northeast Atlantic chub mackerel (Scomber colias) in northern Iberian waters: a first attempt.

Updated information on growth of Atlantic chub mackerel in several areas of its distribution is required for the first stock assessment. Its growth pattern in Northern Iberian waters (2011-2017) is here analyzed with different approaches: those based on otoliths analyses (direct age estimation-DAE, back-calculation-BC and otolith marginal analyses) and those based on length frequency analyses (Bhattacharya, SLCA and PROJMAT methods). Two main different growth patterns are obtained, a "slow" one based on DAE, BC and LFDA from surveys; and a "fast" one based on Bhattacharya and LFDA from commercial landings. The divergence between both patterns begins to be evident at age 3 and older. Otolith marginal analyses that show an annual periodicity in the formation of the hyaline and opaque edge, the unimodal distribution of the annuli radius and the similarity of the back-calculated mean lengths to those obtained by DAE, support the age estimation criteria used in our analysis. The VBGF growth parameters (L∞=45.34, k=0.28, t0=1.18) obtained by otolith age estimation are available for the upcoming stock assessment process

Advances in the study on sexual maturity of Atlantic chub mackerel (Scomber colias) in Cantabrian Sea.

Atlantic chub mackerel (Scomber colias) is a middle size pelagic species distributed on both sides of the Atlantic Ocean. Landings of this species have increased recently in the Iberian Peninsula, likely associated to the increase of its abundance and expansion northwards, probably related to an increment of the sea temperature. The aim of this study is to improve the knowledge of the reproductive biology of the Atlantic chub mackerel and to present updated information on spawning period and maturity ogives that can be used for analytical stock assessment in ICES and its management

Larval fish community in the northwestern Iberian upwelling system during the summer period

The Galician shelf (northwestern Iberian Peninsula) is a highly dynamic area with an important multi-species fisheries industry that exploits resources from several habitats, characterized by being not only highly diverse, rich, and productive but also seasonally and interannually variable. Early life stages of different species are distributed throughout the year, with fluctuating abundances and community composition. Likewise, the influence of environmental factors and processes on larval production and survival remains unknown. Sampling was carried out in July 2012, and all the larvae obtained were identified to establish the specific composition of the community in a summer upwelling scenario. The results show no zonation in the species distribution, a consequence of the mixing effects of the upwelling and eddies, with high diversity but low abundance, which render in a slight predominance of a few species. Due to the dependence of planktonic populations on upwelling events, which was not highly pronounced in 2012, we cannot conclude that this was a typical conformation of the Galician summer larval fish community, but it is a first approach to comprehend the community composition.En prens

Preliminary observation on sexual maturity of chub mackerel (Scomber colias) in the Northern Iberian Atlantic waters (ICES Divisions 27.8.c and 27.9.a.N)

A study of the reproductive biology of the Atlantic chub mackerel (Scomber colias) has been performed in Northern Iberian Atlantic waters (ICES Divisions 27.8.c and 27.9.a.N) based on samples of 14538 specimens (11-50 cm total length) from commercial landings and scientific surveys from 2011-2019. The spawning period was defined based on the monthly prevalence of active females (maturity stages 3, 4 and 5 according to Walsh maturity scale) and temporal variability of females gonado- and hepatosomatic indices (GSI/HSI). Length and age maturity ogives were also estimated for males and females pooling all sampled years together. The spawning period occurred from March to July, with a peak in June. In the 27.8.c area, the GSI, HSI and prevalence of active females increased from March to June and then GSI and prevalence decreased abruptly. In the 27.9.a.N, the peak of spawning was observed earlier (April-May) and with lower intensity than in 27.8.c, but sampling in 27.9.a area was limited to the northern zone (Spanish waters) and are not conclusive. L50 and A50 values estimated with annual data were 22.9 cm and 1.6 years old respectively for both sexes combined, similar to the values estimated with data only from the spawning period: 22.7 cm and 1.5 years old respectively for both sexes combined. Our results were compared with those from previous studies in the NE Atlantic