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9. Linking spawning ground extent to environmental factors--patterns and dispersal during the egg phase of four North Sea fishes

Author

Hoffle, Hannes, Van Damme, Cindy J.G., Fox, Clive, Lelievre, Stephanie, Loots, Christophe, Nash, Richard D.M., Vaz, Sandrine, Wright, Peter J., and Munk, Peter

Subjects
Fishes -- Behavior -- Environmental aspects, Spawning -- Environmental aspects, Fish eggs -- Distribution -- Environmental aspects, Company distribution practices, Earth sciences
Abstract

Previous studies have shown that four commercially important demersal species, namely Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), and European plaice (Pleuronectes platessa), spawn in distinct areas across the North Sea. Based on two comprehensive ichthyoplankton surveys in 2004 and 2009, the present study uses generalized additive mixed models to delimit these spawning grounds using the distribution of recently spawned eggs, investigates their relationship to specific environmental conditions, and examines egg dispersal during their development. Results indicate that presence-absence of early stage eggs is more related to temporal and topographic variables, while egg densities are closely linked with hydrography. Egg distribution patterns were relatively consistent during development and only changed near hatching. Compared with historic observations, the location of the spawning grounds appeared stable on the broad scale but centres of egg abundance varied between the surveyed years. Potential effects of long-term climate change and anthropogenic short-term disturbances, such as seismic surveys, on fish reproduction are discussed, pointing out the demand for multispecies studies on these issues. Des etudes anterieures ont demontre que quatre especes demersales d'importance commerciale, soit la morue franche (Gadus morhua), l'aiglefin (Melanogrammus aeglefinus), le merlan (Merlangius merlangus) et la plie (Pleuronectes platessa), fraient dans des aires distinctes dans la mer du Nord. A la lumiere de deux inventaires exhaustifs de l'ichtyoplancton realises en 2004 et 2009, l'etude fait appel a des modeles additifs generalises mixtes pour delimiter ces lieux de frai sur la base de la repartition des oeufs recemment pondus, explore leur lieu avec differentes conditions ambiantes et examine la dispersion des oeufs durant leur developpement. Les resultats indiquent que la presence ou l'absence d'oeufs precoces est plus fortement reliee a des variables temporelles et topographiques, alors que les densites d'oeufs sont etroitement reliees a l'hydrographie. Les motifs de repartition des oeufs etaient assez constants durant le developpement et ne changeaient qu'a l'approche de l'eclosion. Comparativement aux observations passees, l'emplacement des lieux de frai semblait stable a grande echelle, mais l'emplacement de centres d'abondance d'oeufs etait different pour les deux annees d'inventaire. Les effets potentiels de changements climatiques a long terme et de perturbations d'origine humaine de courte duree, comme des leves sismiques, sur la reproduction des poissons sont abordes, soulignant la pertinence d'etudes plurispecifiques sur ces questions. [Traduit par la Redaction], Introduction Annually visited spawning grounds are a common feature in the life cycle of many fish populations (Daan et al. 1981; Heath et al. 1994) and have been demonstrated for [...]

Published
2018
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10. Evaluating changes in marine communities that provide ecosystem services through comparative assessments of community indicators

Author

Kleisner, Kristin M., Coll, Marta, Lynam, Christopher P., Bundy, Alida, Shannon, Lynne, Shin, Yunne-Jai, Boldt, Jennifer L., Maria F., Borges, Diallo, Ibrahima, Fox, Clive, Gascuel, Didier, Heymans, Johanna J., Juan Jordá, Maria J., Jouffre, Didier, Large, Scott I., Marshall, Kristin N., Ojaveer, Henn, Piroddi, Chiara, Tam, Jorge, Torres, Maria A., Travers-Trolet, Morgane, Tsagarakis, Konstantinos, van der Meeren, Gro I., and Zador, Stephani

Published
2015
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11. Studies on polyunsaturated fatty acid nutrition in the larvae of a marine fish, the herring, Clupea harengus L

Author

Fox, Clive

Subjects
639.8, Unsaturated fatty acids, Fishes--Feeding and feeds, Atlantic herring
Abstract

Despite increasing interest in the culture of cold-water marine fish, a satisfactory inert feed for the larvae of these species has not been developed. As a consequence, the majority of information on the nutritional requirements of the larval stages has been inferred from studies on juvenile or adult fish or derived from manipulations of the nutrient contents of live feeds. Although the latter technique has highlighted the importance of long-chain (n-3) polyunsaturated fatty acids (PUFAs), it is insufficiently precise to define the requirements for individual fatty acids. In this study, the (n-3) PUFA nutrition of the larvae of the herring, Clupea harengus L. was studied. Firstly, the ability of the larvae to elongate and desaturate the fatty acids contained in two strains of brine shrimp, Artemia, was considered. Secondly, the feasibility of rearing herring larvae on an inert, microencapsulated diet was considered. Although it was concluded that long-term rearing trials using this method were not viable at the time, larvae weaned onto the inert feed, from live feed, achieved positive growth. Finally, a novel method for incorporating radiolabelled fatty acids, as metabolic tracers, into herring larvae was developed. The viability of using this system for studying the ability of larvae to elongate and desaturate the fatty acids 18:3(n-3) and 20:5(n-3) was demonstrated. The results from all the trials indicated that a high rate of elongation and desaturation of 18:3(n-3) does not occur in herring larvae. Although some ability to elongate 20:5(n-3) to 22:5(n-3) was demonstrated, significant desaturation of this fatty acid to 22:6(n-3) did not occur. It is suggested that the rate of bioconversion of 20:5(n-3) to 22:6(n-3) is too low to be of nutritional significance.

Published
1990

12. Physiological condition, short-term survival, and predator avoidance behavior of discarded Norway lobsters (Nephrops norvegicus)

Author

Albalat, Amaya, Collard, Arnaud, McAdam, Bruce, Coates, Christopher J., and Fox, Clive J.

Subjects
Trawling -- Physiological aspects, Biological sciences, Zoology and wildlife conservation, European Union
Abstract

ABSTRACT The landing obligation of the reformed European Union Common Fisheries Policy is designed to encourage more selective fishing strategies and improve recording of catches. There are allowable exemptions to [...]

Published
2016
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17. Working Group on Ecosystem Assessment of Western European Shelf Seas (WGEAWESS)

Author

Abrantes, Fatima, Andonegi, Eider, Beggs, Steven, Bentley, Jacob, Borges, Fátima, Christensen, Villy, Corrales, Xavier, Depestele, Jochen, Fariñas, Andrea, Fox, Clive, Gal, Gideon, Gascuel, Didier, Halouani, Ghassen, Heymans, Sheila, Holdsworth, Neil, Issac, Pierre, Kalinina, Olga, Kellner, Julie, Kempf, Jed, Kraan, Marloes, Lehuta, Sigrid, Llope, Marcos, López, Romain, Martinez, Inigo, Motova, Arina, Payne, Mark, Pedreschi, Debbi, Piroddi, Chiara, Potier, Mikaëla, Preciado, Izaskun, Püts, Miriam, Ramirez-Monsalve, Paulina, Reid, Dave, Rufino, Marta, Salgueiro, Emilia, Schoenen, Lea, Schuchert, Pia, Seixas, Sónia, Serpetti, Natalia, Silvar Viladomiu, Paula, Steenbeek, Jeroen, Szalaj, Dorota, Tomczak, Maciej, Torres, Marian, Travers-Trolet, Morgane, Vernhout, Gerben, and Villanueva, Ching

Subjects
Bay of Biscay and the Iberian Coast (ICES Ecoregion), Ecosystem observation, processes and dynamics, Celtic Seas (ICES Ecoregion), Pressures, impacts, conservation, and management
Abstract

The ICES Working Group on Ecosystem Assessment of Western European Shelf Seas (WGEA-WESS) aims to provide high quality science in support to holistic, adaptive, evidence-based man-agement in the Celtic seas, Bay of Biscay and Iberian coast regions. The group works towards developing integrated ecosystem assessments for both the (i) Celtic Seas and (ii) Bay of Biscay and Iberian Coast which are summarized in the Ecosystem Overviews (EOs) advice products that were recently updated. Integrated Trend Analysis (ITA) were performed for multiple sub-ecoregions and used to develop an understanding of ecosystem responses to pressures at varying spatial scales. Ecosystem models (primarily Ecopath with Ecosim; EwE) were developed and identified for fisheries and spatial management advice. The updated Celtic Seas EO represents a large step forward for EOs, with the inclusion of novel sections on climate change, foodweb and productivity, the first application of the new guidelines for building the conceptual diagram, inclusion of socio-economic indicators, and progress made toward complying with the Transparent Assessment Framework (TAF). We highlight ongoing issues relevant to the development and communication of EO conceptual diagrams. A common methodology using dynamic factor analysis (DFA) was used to perform ITA in a comparable way for seven subregions. This was supported by the design and compilation of the first standardized cross-regional dataset. A comparison of the main trends evidenced among subregions over the period 1993–2020 was conducted and will be published soon. A list of available and developing EWE models for the region was also generated. Here, we re-port on the advances in temporal and spatial ecosystem modelling, such as their capacity to model the impacts of sector activities (e.g. renewables and fisheries) and quantify foodweb indi-cators. We also reflect on model quality assessment with the key run of the Irish sea EwE model. The group highlighted the hurdles and gaps in current models in support of EBM, such as the choice of a relevant functional, spatial, and temporal scales and the impacts of model structure on our capacity to draw comparisons from models of different regions. The group aims to ad-dress these issues in coming years and identify routes for ecosystem model derived information into ICES advice. info:eu-repo/semantics/publishedVersion

Published
2022
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28. Refining Fisheries Advice With Stock-Specific Ecosystem Information

Author

Bentley, Jacob W., primary, Lundy, Mathieu G., additional, Howell, Daniel, additional, Beggs, Steven E., additional, Bundy, Alida, additional, de Castro, Francisco, additional, Fox, Clive J., additional, Heymans, Johanna J., additional, Lynam, Christopher P., additional, Pedreschi, Debbi, additional, Schuchert, Pia, additional, Serpetti, Natalia, additional, Woodlock, Johnny, additional, and Reid, David G., additional

Published
2021
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30. Community-Level Impacts Of Trawl Selectivity In The Eastern Mediterranean Sea Assessed Using An Ecosystem Modelling Approach

Author

Saygu, Ismet, Heymans, Johanna J., Fox, Clive, Ozbilgin, Huseyin, Bentley, Jacob W., Eryasar, Ahmet Raif, and Gokce, Gokhan

Abstract

Switching from the traditional 40- or 44-mm diamond mesh codends to 50-mm diamond mesh (D50) or 40-mm square mesh (S40) codends is known to improve the size selection for commercial species and reduce discarding in the Mediterranean demersal trawl fisheries. This change has been recommended in the General Fisheries Commission for the Mediterranean and European Commission regulations. However, ecosystem-based assessment of improved selectivity still remains a challenge, and that is the aim of this study. For this purpose, an Ecopath model was developed and used to initialize dynamic simulations in Ecosim. The simulations changed gear-specific fishing mortality rates to represent the shifting from traditional codend to alternative codends. Our results suggest that the use of D50 or S40 codends would have a positive impact on the ecosystem as a whole and on the stock status of several commercial and non-commercial groups. Mixed trophic impact analysis indicated that, for species, like red mullet, the S40 codend was significantly better than the D50 codend. This information can be useful to policymakers, particularly for the areas where red mullet is the main target species and could inform trawl mesh options in the eastern Mediterranean.

Published
2020

48. How well do connectivity tools agree over the full life cycle? A case study of Irish Sea plaice Pleuronectes platessaLinnaeus, 1758.

Author

Geffen, Audrey J., Nash, Richard D. M., and Fox, Clive J.

Subjects
*LIFE cycles (Biology), *PLAICE, *OTOLITHS, *MICROCHEMISTRY, *SIGNALS & signaling
Abstract

Adult plaice in the Irish Sea have distinct traits that reflect the spawning locations that could suggest a number of different populations. However, do connectivity pathways support this concept? Different tools are directed at measuring exchange or connectivity between different life‐history stages, and the challenge is to integrate the signals to obtain full life‐cycle estimates. Collectively, the different methods reveal stable connectivity between known spawning and nursery grounds, with sufficient exchange to maintain a single population with weak genetic structure. [ABSTRACT FROM AUTHOR]

Published
2024
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