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

Individual variability and sex-related differences in the growth of Diplodus annularis (Linnaeus, 1758)

10 páginas, 1 tabla, 10 figurasVariability and changes in the individual life-history parameters of fishes are frequently overlooked, and it is assumed that all individuals mature, spawn, grow, and die at the same rates over their lifespans. Here, the variability in the individualgrowth of the rudimentary hermaphrodite Diplodus annularis (Linnaeus, 1758) is described using a Bayesian approach. This approach enables the inference of individualgrowth curves, even in a species of a relatively short lifespan, and revealed a biphasic growth pattern for this species. Conventional von Bertalanffy growth failed to fit the individual back-calculated lengths-at-age data well. A generalization of this model is proposed for accommodating one change in the growth rate at some moment of the lifespan of this species. This novel five-parameter model (L∞, k0, k1, t0 and t1, i.e., size at infinite age, initial and final growth rate, age at size zero and age at the change of growth rate) represents the different allocation of energy to somatic growth or reproduction, prior to and post-sexual maturity. Moreover, between-sexgrowthdifferences are described; juvenile fish display similar growth rates in both sexes, but mature females have lower growth rates than males. The detailed description of the growth of the D. annularis shown here can provide adequate input for future implementation of population dynamics models that take into account individualvariability (e.g., IBMs, individual-based models). These models could facilitate the management of a species targeted by recreational fishery.This study was founded by the research project ROQUER (CTM2005-00283) funded by Ministerio de Educación y Ciencia of the Spanish Government. Finally, we would like to thank two anonymous reviewers for their useful comments. The first author was supported by a FPI fellowship (MICINN).Peer reviewe

MPA network design based on graph network theory and emergent properties of larval dispersal

Despite the recognised effectiveness of networks of Marine Protected Areas (MPAs) as a biodiversity conservation instrument, nowadays MPA network design frequently disregards the importance of connectivity patterns. In the case of sedentary marine populations, connectivity stems not only from the stochastic nature of the physical environment that affects early-life stages dispersal, but also from the spawning stock attributes that affect the reproductive output (e.g., passive eggs and larvae) and its survivorship. Early-life stages are virtually impossible to track in the ocean. Therefore, numerical ocean current simulations coupled to egg and larval Lagrangian transport models remain the most common approach for the assessment of marine larval connectivity. Inferred larval connectivity may be different depending on the type of connectivity considered; consequently, the prioritisation of sites for marine populations' conservation might also differ. Here, we introduce a framework for evaluating and designing MPA networks based on the identification of connectivity hotspots using graph theoretic analysis. We use as a case of study a network of open-access areas and MPAs, off Mallorca Island (Spain), and test its effectiveness for the protection of the painted comber Serranus scriba. Outputs from network analysis are used to: (1) identify critical areas for improving overall larval connectivity; (2) assess the impact of species' biological parameters in network connectivity; and (3) explore alternative MPA configurations to improve average network connectivity. Results demonstrate the potential of graph theory to identify non-trivial egg/larval dispersal patterns and emerging collective properties of the MPA network which are relevant for increasing protection efficiency.Comment: 8 figures, 3 tables, 1 Supplementary material (including 4 table; 3 figures and supplementary methods

Thermal reaction norms in sperm performance of Atlantic cod (Gadus morhua)

13 páginas, 6 figuras, 2 tablas[EN] Phenotypic plasticity occurs when a genotype produces variable phenotypes under different environments; the shapes of such responses are known as norms of reaction. The genetic scale at which reaction norms can be determined is restricted by the experimental unit that can be exposed to variable environments. This has limited their description beyond the family level in higher organisms, thus hindering our understanding of differences in plasticity at the scale of the individual. Using a three-year common-garden experiment, we quantify reaction norms in sperm performance of individual genotypes within different families of Atlantic cod (Gadus morhua). Cod sperm showed phenotypic plasticity in swimming performance across temperatures (3, 6, 11, and 21 °C), but the pattern of the response depended upon how long sperm had been swimming (30, 60, 120, or 180 s), i.e., plasticity in plasticity. Sperm generally swam fastest at intermediate temperatures when first assessed at 30 s after activation. However, a significant genotype × environment interaction was present, indicating inter-individual differences in phenotypic plasticity. To our knowledge, this is the first study to describe variable sperm performance across environmental conditions as a reaction norm. The results have potential theoretical, conservation, and aquaculture implications[FR] Il se produit une plasticité phénotypique lorsqu’un génotype détermine des phénotypes qui varient en fonction des différents environnements; les formes de telles réactions sont connues sous le nom de normes de réaction. L’échelle génétique à laquelle les normes de réaction peuvent être déterminées est restreinte par l’unité expérimentale qui peut être exposée à des environnements variables. Cela a limité leur description au-delà du niveau de la famille chez les organismes supérieurs, ce qui a entravé notre compréhension des différences de plasticité à l’échelle des individus. Dans une expérience de trois ans en jardin commun, nous avons mesuré les normes de réaction dans la performance des spermatozoïdes de génotypes individuels dans différentes familles de morues franches (Gadus morhua) de l’Atlantique. Les spermatozoïdes de morues font montre de plasticité phénotypique dans leur performance de nage sur une gamme de températures (3, 6, 11, et 21 8C), mais le patron de la réaction dépend du temps que le spermatozoïde a déjà consacré à la nage (30, 60, 120, ou 180 s), c’est donc une plasticité dans la plasticité. Les spermatozoïdes nagent généralement le plus vite aux températures intermédiaires lorsqu’ils sont évalués 30 s après leur activation. Cependant, il existe une interaction significative génotype environnement, ce qui indique qu’il y a des différences de plasticité phénotypique entre les individus. À notre connaissance, notre étude est la premiére à décrire une performance variable des spermatozoïdes comme des normes de réaction sur une gamme de conditions du milieu. Nos résultats ont des incidences théoriques potentielles, mais aussi des conséquences sur la conservation et l’aquacultureFunding was provided by a faculty startup award from Memorial University of Newfoundland to C.F.P., the Atlantic Cod Genomics and Broodstock Development Program and the Fisheries and Oceans Canada Aquaculture Collaborative Research Development Program to E.A.T., a scholarship from the Natural Sciences and Engineering Research Council of Canada to I.A.E.B, and a grant from Xunta de Galicia, inside de INCITE program, to A.A.- F. All animals were handled according to guidelines set by the Canadian Council on Animal CarePeer reviewe

Características del rendimiento reproductivo del hermafrodita simultáneo Serranus scriba en el Mediterráneo Occidental (Islas Baleares)

We studied multiple individual parameters that affect the reproductive output in the painted comber Serranus scriba, a simultaneous hermaphroditic fish that is widely exploited by recreational fishing in temperate marine coastal regions. Batch fecundity was significantly affected by maternal size, but was not related to maternal age or condition. However, egg quality as estimated by egg dry weight was significantly influenced by the interaction effect of maternal size and age. An empirical assessment demonstrated the existence of a diel spawning pattern based on a daily release of a partial fraction of eggs related to sunset time. Buoyancy varied during the incubation period, but it consistently resulted in positive buoyancy that situated the eggs near the top of the water column. This study represents the first estimation of reproductive output of the simultaneous hermaphrodites S. scriba and also provides a comprehensive study about the potential maternal factors that affect egg production. These results are a crucial step towards ongoing efforts to improve the stock assessment of this species.Se estudiaron varios parámetros individuales que afectan el éxito reproductivo de la especie Serranus scriba, un pez hermafrodita simultáneo que es intensamente explotado por la pesca recreativa en regiones costeras de aguas templadas. La fecundidad parcial está significativamente relacionada con el tamaño de los individuos; pero no se encontró relación con la edad o condición. Sin embargo, la calidad de los huevos (estimada a partir del peso seco) resultó significativamente influenciada por la interacción del tamaño y edad de los individuos. Se demostró empíricamente la existencia de un patrón de desove diario, basado en la puesta diaria de una fracción de los huevos del total con anterioridad a la puesta del sol. La flotabilidad de los huevos varió durante el período de incubación; pero presentando de forma consistente una flotabilidad positiva que sitúa a los huevos liberados cerca de la parte más superficial de la columna de agua. Este estudio representa la primera estimación de los parámetros reproductivos relacionados con la producción de huevos en el hermafrodita simultáneo Serranus scriba. Proporciona además un detallado estudio sobre los posibles factores parentales que afectan a la producción de huevos en esta especie. Estos resultados son un paso fundamental para los esfuerzos en curso para mejorar la evaluación y gestión de las poblaciones de Serranus scriba

Unusual occurrences of fishes along the Northeast Atlantic: new biological and distributional data

The occurrences of 13 specimens belonging to 9 species of little known marine fishes in the Northeast Atlantic in 2017 and 2018 are reported. Information about the morphology and new findings of Decapterus tabl and Decapterus macarellus (Carangidae), Kyphosus vaigiensis (Kyphosidae), Remora osteochir (Echeneidae), Antigonia capros (Caproidae), Hyperoglyphe perciformis (Centrolophidae), Halobatrachus didactylus (Batrachoididae), Parapristipoma octolineatum (Haemulidae) and Zu cristatus (Trachypteridae) are reported in different locations, where they are categorized as unusual or rare. Morphometric and meristic parameters confirm the identification to species level of each specimen, also supported by DNA barcoding. Histological examination of reproductive tissue is carried out in four specimens to know the sex and their reproductive stage. All species are known from other areas of the Atlantic Ocean, but these findings are an important contribution to understanding their biology and distribution. These include a new northernmost record of Remora osteochir and Decapterus tabl in the eastern Atlantic and the first records of Antigonia capros, Hyperoglyphe perciformis, Halobatrachus didactylus and Parapristipoma octolineatum from Galician waters

Drivers of the spatial behaviour of the threatened thornback skate (Raja clavata)

Fish movements are fundamental to their ecology and survival. Understanding the causes and consequences of the spatial behaviour of fish is of high relevance as it provides critical knowledge for conservation purposes. Skate (Rajidae) populations face an unprecedented global decline due to overfishing. In this study, we used acoustic telemetry to track the movements of nine individuals of the near threatened thornback skate (Raja clavata) around the Cíes Islands, a small marine protected area in the northwest of the Iberian Peninsula. Our results demonstrate the significant impacts of biotic and abiotic drivers on the spatial behaviour of R. clavata. Overall residency inside the study array was low (0.073), differed between sexes (higher for females) and over the course of the year (peaking in summer). The analysis of the direction of the excursions performed by R. clavata individuals revealed high consistency in the exit and entry areas and a strong connectivity with inshore waters connecting with the Ría de Vigo, as compared with offshore waters connecting with the open ocean. Finally, the activity space of R. clavata also varied over the time of the year with a peak in summer. This study provides an important baseline information for understanding the spatial behaviour of R. clavata that can serve as a starting point for planning future conservation actions or studies

From Galician waters to cetacean stomachs, a feeding story told by preys

34th European Cetacean Society Conference, O Grove, 16-20 April 2023Cetaceans play an important role in maintaining the health and stability of marine ecosystems. To understand the trophic relationships of these top predators in waters off the Northwest Iberian Peninsula, and to determine their possible competition with fisheries, the stomach contents of 751 common dolphins (Delphinus delphis), 60 striped dolphins (Stenella coeruleoalba), 124 bottlenose dolphins (Tursiops truncatus), and 72 harbour porpoises (Phocoena phocoena) stranded on the Galician coast between 1990-2018 (almost 30 years) were analysed. Results indicated that their diets are mainly piscivorous (after identified 90 different taxa: 68 fish and 22 cephalopods), being the blue whiting (Micromesistius poutassou) and the European hake (Merluccius merluccius) the most important preys (in occurrence, number, and biomass) throughout all the years studied and for the four cetacean species. The long time series available allowed to detect interannual variation in the diet of both common dolphins and harbour porpoises by means of Generalised Additive Models (GAMs), observing an increase in the presence of European hake and a decrease of sardines (Sardina pilchardus) in the stomachs through time. Seasonal variation in the diets of the common and striped dolphins were also observed, with a higher consumption of blue whiting during the summer (May-September). Significant differences were found in the diet of the two bottlenose dolphin ecotypes present in Galicia, the coastal ecotype contains a higher percentage of demersal preys in the stomachs, while the oceanic ecotype contains more pelagic preys, confirming the habitat separation between the two. Results also confirmed an ontogenic variability in the diet of harbour porpoises, with juvenile animals showing a higher presence of coastal preys in the diet (e.g., pouting – Trisopterus luscus). There is an overlap between the diet of these four cetacean species and the fisheries‟ target species in the area, indicating competition for some resourcesN

Assessment of the status of small-scale fisheries resources in north-west Spain (Galicia) using length- based assessment methods

2nd Iberian Symposium on Modeling and Assessment of Fishery Resources (SIMERPE2) = 2º Simposio Ibérico de Modelado y Evaluación de Recursos Pesqueros, 24-27 October 2023, El puerto de Santa MaríaSmall-scale fisheries (SSFs) are major contributors to global catches and local economies, yet SSFs have historically been under-represented in national and international policies. In the European Union (EU), more than 80% of the fishing fleet is considered small-scale, and Galicia (NW Spain) is one of the most fisheries-dependent regions in Europe, with around 4000 fishing vessels, of which ~90% are registered as artisanal vessels. However, due to various data limitations, there is a lack of formal assessment of the main commercial species that could be used to implement better management practices. To overcome this shortcoming, and considering that length-frequency data from fisheries catches are probably the most common source of demographic information, a number of length-based methods (LBM) are available as potential assessment tools for use in data-limited scenarios. Therefore, in order to provide insight into the stock status of the main fishery resources of the Galician SSF (12 species of Teleostei, two Chondrichthyes, two Crustacea and two Cephalopoda), we applied two of the most commonly used LBMs, namely length-based indicators (LBI) and length-based spawning potential ratio (LBSPR), and one of the few models that relax the equilibrium assumption, such as the lengthbased integrated mixed effects (LIME). The selected LBMs were applied to the individual size data collected by the Galician Regional Government through the on-board monitoring programme of the SSF fleet, managed by its Technical Unit for Small-scale Fisheries (UTPB), for the period 2000 - 2022. To get an idea of the performance of the LBMs, for each stock we compared the results of the data-limited assessment with time series of the abundance index resulting from the standardization of catch-per-unit-of-effort (CPUE) data collected by the UTPB. This study represents a major step forward in the development of a stock assessment and management framework for one of Europe’s most important SSF fleets, based on the best available data and scientific toolsN