Marianna Giannoulaki | Hellenic Centre of Marine Research (original) (raw)

Papers by Marianna Giannoulaki

Marine Ecology Progress Series, Dec 5, 2011

Ecosystem-based management (EBM) requires more extensive information than singlespecies managemen... more Ecosystem-based management (EBM) requires more extensive information than singlespecies management. Active underwater acoustic methods provide a means of collecting a wealth of ecosystem information with high space-time resolution. Worldwide fisheries institutes and agencies are carrying out regular acoustic surveys covering many marine shelf ecosystems, but these data are underutilized. In addition, more and more acoustic data collected by vessels of opportunity are becoming available. To encourage their use for EBM, we provide a brief introduction to acoustic and complementary data collection methods in the water column, and review current and potential contributions to monitoring population abundance and biomass, spatial distributions, and predator-prey relationships. Further development of acoustics-derived indicators is needed. We review and propose indicators for assessing and monitoring zooplankton, population dynamics of fish and other nekton, and changes in diversity and food-web functioning. Acoustic methods have the potential to make a strong contribution to EBM. Evaluation of new indicators and suitable reference points in different ecosystems are the current challenges.

Legal Notice Neither the European Commission nor any person acting on behalf of the Commission is... more Legal Notice Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use which might be made of this publication. This report does not necessarily reflect the view of the European Commission and in no way anticipates the Commission's future policy in this area. Europe Direct is a service to help you find answers to your questions about the European Union Freephone number (*): 00 800 6 7 8 9 10 11 (*) Certain mobile telephone operators do not allow access to 00 800 numbers or these calls may be billed. A great deal of additional information on the European Union is available on the Internet.It can be accessed through the Europa server http://europa.eu/ JRC 97817 EUR 27484 EN

PLOS ONE, 2014

<p>Only significant values (p<0.001) are reported. ns: non significant.</p

PLOS ONE, 2014

<p>Biomass estimates of <i>Engraulis encrasicolus</i> (E.E.) and <i>Sardi... more <p>Biomass estimates of <i>Engraulis encrasicolus</i> (E.E.) and <i>Sardina pilchardus</i> (S.P.) in the Strait of Sicily (upper part) and in the North Aegean Sea (lower part).</p

Mediterranean Marine Science, 2021

Special Issue for 2021 dedicated to papers produced within the MEDIAS project. Guest editors: Mar... more Special Issue for 2021 dedicated to papers produced within the MEDIAS project. Guest editors: Marianna Giannoulaki, Juan Zwolinski, Ali Cemal Gucu, Andrea De Felice, and Stylianos Somarakis.

This report presents an overview of the Targeted Products of the Challenge 2 (Marine Protected Ar... more This report presents an overview of the Targeted Products of the Challenge 2 (Marine Protected Areas). It describes the methodology used to develop the products and attempts to answer some of the primary questions regarding the adequacy and representativity of the Mediterranean Marine Protected Areas-Fisheries Restricted Areas network.

Med protection initiatives (management and conservation areas)

Mediterranean Marine Science, 2019

Multispecies ichthyoplankton associations are believed to be adaptive and their objective definit... more Multispecies ichthyoplankton associations are believed to be adaptive and their objective definition can be useful in designating species with similar or contrasting spawning strategies. In this case study, a suite of indicators, recently developed to characterize the spatial patterns of animal populations, are applied on egg abundance data of summer-spawning European anchovy (Engraulis encrasicolus), round sardinella (Sardinella aurita) and chub mackerel (Scomber colias), in an effort to identify common or contrasting spawning patterns in the North-East Aegean Sea (NEA) and their relation to the major oceanographic features of the area. A considerable increase in abundance and area of presence was observed between the early (May) and advanced (July) phase of the 2010 spawning period. The definition of major spatial patches revealed a persistent multispecies spawning location associated with the outflow of Black Sea water (BSW). A second major patch was defined for anchovy and chub ...

CM Documents - ICES, 2013

Summary Within the current work, the habitat of small pelagic fish populations in the Mediterrane... more Summary Within the current work, the habitat of small pelagic fish populations in the Mediterranean was assessed combining historic survey data (i.e. acoustic, ichthyoplankton, bottom trawl surveys) from five different areas along with satellite environmental and bathymetry data. Selected models were used to produce annual habitat suitability maps over the period 2000‐ 2 010 addressing different life stages (i.e. adults, juveniles and eggs) of the target species at a spatial resolution of 4x4 km. Based on these annual maps, habitat persistency maps were produced using GIS techniques where persistent and occasional locations suitable for nurseries and spawning grounds were identified. These areas are discussed in re lation to existing fishing restricted areas in the Mediterranean Sea.

Recent Advances in Environmental Science from the Euro-Mediterranean and Surrounding Regions (2nd Edition), 2021

Information integrated from different parts of the Mediterranean was used in order to model the s... more Information integrated from different parts of the Mediterranean was used in order to model the spatial and temporal variability of the distribution grounds of sardine. Acoustic data as recorded with a 38 kHz split beam echosounder from the Aegean Sea (Eastern Mediterranean), the Adriatic Sea (Central Mediterranean), the Sicily Channel (Central Mediterranean) and the Spanish waters (Western Mediterranean) have been analyzed along with satellite environmental and bathymetry data to model the spatial distribution of sardine during summer, autumn and early winter. Similarly, egg distribution data from the Spanish waters were used to model the potential spawning habitat of sardine during early winter. Satellite data were used as proxies to infer spatial variations of environmental factors and assess possible ecological relationships. Generalized Additive Models were applied in a presence/absence approach. Model results were evaluated based on the estimation of the area under the receive...

Regional Studies in Marine Science, 2021

Abstract Spatial management of discards has attracted increasing interest as a potential mitigati... more Abstract Spatial management of discards has attracted increasing interest as a potential mitigation measure. However, most studies are restricted to commercial species. The aim of the present work was to fill this gap by identifying and mapping the spatial distribution of five non-commercial species with high frequency of occurrence in the discarded catch of bottom trawl fishery in the Aegean Sea, i.e., Brown comber Serranus hepatus, Mediterranean scaldfish Arnoglossus laterna, Red bandfish Cepola macrophthalma, Argentine Argentina sphyraena, and Boarfish Capros aper. For this purpose, Generalized Additive Models were used to account for catch dependency on environmental parameters in order to explore the spatial distribution of species. Modeling results revealed that the spatial distribution of species was driven by environmental variables. Depth was the most informative variable explaining most catch variation in all species. For A. laterna, C. macrophthalma, and S. hepatus the highest estimated values of catch were located over the continental shelf and at shallower waters inside gulfs, whereas C. aper and A. sphyraena catch were more broadly distributed across the study area and at greater depths. Seasonal variations in species catch were also observed, probably related in most cases to species reproduction period. Mapping species distribution is essential for the identification of priority areas of protection in future marine spatial plans.

Fisheries Research, 2020

Abstract Discards is an important issue in fisheries around the world. The spatial management of ... more Abstract Discards is an important issue in fisheries around the world. The spatial management of discards has attracted interest as a potential tool for minimizing the unwanted catch. The aim of the present work was to identify areas with high quantities of bottom trawl discarded catch regarding species subjected to MCRS, in six areas of southern European waters (southern Portuguese waters, Catalan Sea, Ligurian and northern Tyrrhenian Seas, Strait of Sicily, eastern Ionian Sea, and Aegean Sea). Analyses were based on two types of data: (a) the undersized catch of species subjected to MCRS from bottom trawl surveys and (b) the actual discarded catch (including undersized and non-undersized individuals) of species subjected to MCRS from commercial bottom trawling. Geostatistical analysis techniques were applied to the first type of data and Generalized Additive Models using environmental variables were applied to the second one. Subsequently, areas that persistently presented high quantities of discarded catch (i.e., “iDC grounds”) or undersized catch (i.e., “iUC grounds”) were identified and mapped. The “iDC grounds”/“iUC grounds” were located either over the slope or within the continental shelf and over marine plateaus, largely depending on the main target species of each fishery. Next, the overlap of “iDC grounds”/“iUC grounds” with the existing Fisheries Restricted Areas (FRAs) and the proposed Marine Protected Areas (MPAs) was estimated aiming to explore how spatial closures could contribute to the reduction of bottom trawl discarded catch/undersized catch. Certain spatial closures were more effective in the Central Mediterranean and others to the Eastern Mediterranean. The overlapping of existing FRAs with “iDC grounds”/“iUC grounds” did not exceed 24 % in any study area, whereas proposed MPAs, like the CIESM Marine Peace Parks, reached up to 90 % for the same study area.

Mediterranean Marine Science, 2021

We present the development of a 3D full-lifecycle, individual-based model (IBM) for anchovy and s... more We present the development of a 3D full-lifecycle, individual-based model (IBM) for anchovy and sardine, online coupled to an existing hydrodynamic/biogeochemical low-trophic level (LTL) model for the North Aegean Sea. It was built upon an existing 1D model for the same species and area, with the addition of a horizontal movement scheme. In the model, both species evolve from the embryonic stage (egg+yolk sac larva) to the larval, juvenile, and adult stages. Somatic growth is simulated with the use of a “Wisconsin” type bioenergetics model and fish populations with an adaptation of the ‘super individuals’ (SI) approach. For the reference simulation and model calibration, in terms of fish growth and population biomass, the 2000-2010 period was selected. Interannual biomass variability of anchovy was successfully represented by the model, while the simulated biomass of sardine exhibited low variability and did not satisfactorily reproduce the observed interannual variability from acou...

Mediterranean Marine Science, 2021

The study of small pelagic fish by hydroacoustic methods in the Mediterranean Sea began in the A... more The study of small pelagic fish by hydroacoustic methods in the Mediterranean Sea began in the Adriatic in the 1950’s. Since 2009, internationally coordinated, extensive, regular surveys have been conducted in the framework of the MEDIAS - Mediterranean International Acoustic Surveys – action, under the EU Data Collection Framework, to provide inputs for the management of small pelagics, particularly European anchovy (Engraulis encrasicolus) and European sardine (Sardina pilchardus). The surveys cover EU Mediterranean waters and monitor the distribution and abundance of small pelagic species using a common protocol. The hydroacoustic surveys, historically conducted by each Country separately, have since been standardized and harmonized. This is a review of the evolution of the surveys from the beginning up to the present and discusses the future prospects. It reports the historical time series of anchovy, sardine and other small pelagics in different areas and describes the spatial...

Journal of Sea Research, 2018

Abstract The mitigation and incorporation of fisheries discards into the spatial management persp... more Abstract The mitigation and incorporation of fisheries discards into the spatial management perspective call for a well-planned approach considering their high spatiotemporal variability. This study describes an approach to map the spatiotemporal distribution of bottom trawl discards taking into account on-board observer data, environmental information and high-resolution estimates of fishing effort derived from Vessel Monitoring System data. Two were the main objectives: i) mapping the Discards Per Unit Effort (DPUE: kg/h) and ii) mapping the total discards quantities (in kg) in a predefined spatial unit (grid cell of 5 × 5 km). For this purpose, discards data from commercial bottom trawlers (seasonal basis, period 2003–2006, 2008) operating on the continental shelf of the eastern Ionian Sea were analyzed. The DPUE for a) all species with Minimum Landing Size (MLS), b) all species without MLS and c) all fish species, were modeled by means of Generalized Additive Models (GAMs) using satellite environmental parameters, bathymetry and season as independent covariates. Mapping discards quantities in a predefined spatial unit was based on the spatial overlapping between GAM estimates for the year 2010 and fishing effort distribution for the same year. Spatial clusters of high discard quantities (hot spots) and their spatiotemporal persistence were also investigated. Results revealed how the environmental and temporal factors influence the DPUE distribution of each discard group and indicated increased discards quantities in areas of high fishing effort. The potential implications of the resulting DPUE maps for advancing discards spatial mitigation are further discussed. Mapping discards quantities using both the DPUE and the fishing effort distribution provide valuable insights that can be useful to investigate the broader ecosystem consequences of the EU landing obligation and other potential fishery management policies.

Marine Ecology Progress Series, 2019

Under the general framework of existing recruitment hypotheses, knowledge on the drivers and mech... more Under the general framework of existing recruitment hypotheses, knowledge on the drivers and mechanisms involved in the determination of the year class strength of small pelagic fish (SPF) is briefly reviewed with focus on selected aspects of the adult and larval stages, related to breeding patterns, egg production, spawning habitats, reproductive potential and early life survival. An analysis of stock−recruitment time series data is carried out, showing that the maximum recruitment capacity of clupeoid stocks increases with the strength of temporal autocorrelation in recruitment (R) and decreases as the coefficient of variation of R becomes larger. Reproductive strategy in combination with the thermal and trophic conditions of the ecosystem and the life cycle pattern of the stock can influence the relative importance of high and low frequency variability in recruitment that combine to generate the population fluctuations of SPF. Selective fishing can reduce the reproductive potential and alter the spawning phenology of the stocks. To understand the ways by which the distribution, abundance and survival of larval stages are influenced by trophodynamic and physical factors, it is important to recognize all those milestones in fish ontogeny associated with significant changes in capabilities and behavior (e.g. onset of schooling). Temperature affects many parameters related to egg production and early life survival, but the relative importance of such temperature effects is expected to differ substantially in contrasting SPF habitats.

Marine Ecology Progress Series, Dec 5, 2011

Ecosystem-based management (EBM) requires more extensive information than singlespecies managemen... more Ecosystem-based management (EBM) requires more extensive information than singlespecies management. Active underwater acoustic methods provide a means of collecting a wealth of ecosystem information with high space-time resolution. Worldwide fisheries institutes and agencies are carrying out regular acoustic surveys covering many marine shelf ecosystems, but these data are underutilized. In addition, more and more acoustic data collected by vessels of opportunity are becoming available. To encourage their use for EBM, we provide a brief introduction to acoustic and complementary data collection methods in the water column, and review current and potential contributions to monitoring population abundance and biomass, spatial distributions, and predator-prey relationships. Further development of acoustics-derived indicators is needed. We review and propose indicators for assessing and monitoring zooplankton, population dynamics of fish and other nekton, and changes in diversity and food-web functioning. Acoustic methods have the potential to make a strong contribution to EBM. Evaluation of new indicators and suitable reference points in different ecosystems are the current challenges.

Legal Notice Neither the European Commission nor any person acting on behalf of the Commission is... more Legal Notice Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use which might be made of this publication. This report does not necessarily reflect the view of the European Commission and in no way anticipates the Commission's future policy in this area. Europe Direct is a service to help you find answers to your questions about the European Union Freephone number (*): 00 800 6 7 8 9 10 11 (*) Certain mobile telephone operators do not allow access to 00 800 numbers or these calls may be billed. A great deal of additional information on the European Union is available on the Internet.It can be accessed through the Europa server http://europa.eu/ JRC 97817 EUR 27484 EN

PLOS ONE, 2014

<p>Only significant values (p<0.001) are reported. ns: non significant.</p

PLOS ONE, 2014

<p>Biomass estimates of <i>Engraulis encrasicolus</i> (E.E.) and <i>Sardi... more <p>Biomass estimates of <i>Engraulis encrasicolus</i> (E.E.) and <i>Sardina pilchardus</i> (S.P.) in the Strait of Sicily (upper part) and in the North Aegean Sea (lower part).</p

Mediterranean Marine Science, 2021

Special Issue for 2021 dedicated to papers produced within the MEDIAS project. Guest editors: Mar... more Special Issue for 2021 dedicated to papers produced within the MEDIAS project. Guest editors: Marianna Giannoulaki, Juan Zwolinski, Ali Cemal Gucu, Andrea De Felice, and Stylianos Somarakis.

This report presents an overview of the Targeted Products of the Challenge 2 (Marine Protected Ar... more This report presents an overview of the Targeted Products of the Challenge 2 (Marine Protected Areas). It describes the methodology used to develop the products and attempts to answer some of the primary questions regarding the adequacy and representativity of the Mediterranean Marine Protected Areas-Fisheries Restricted Areas network.

Med protection initiatives (management and conservation areas)

Mediterranean Marine Science, 2019

Multispecies ichthyoplankton associations are believed to be adaptive and their objective definit... more Multispecies ichthyoplankton associations are believed to be adaptive and their objective definition can be useful in designating species with similar or contrasting spawning strategies. In this case study, a suite of indicators, recently developed to characterize the spatial patterns of animal populations, are applied on egg abundance data of summer-spawning European anchovy (Engraulis encrasicolus), round sardinella (Sardinella aurita) and chub mackerel (Scomber colias), in an effort to identify common or contrasting spawning patterns in the North-East Aegean Sea (NEA) and their relation to the major oceanographic features of the area. A considerable increase in abundance and area of presence was observed between the early (May) and advanced (July) phase of the 2010 spawning period. The definition of major spatial patches revealed a persistent multispecies spawning location associated with the outflow of Black Sea water (BSW). A second major patch was defined for anchovy and chub ...

CM Documents - ICES, 2013

Summary Within the current work, the habitat of small pelagic fish populations in the Mediterrane... more Summary Within the current work, the habitat of small pelagic fish populations in the Mediterranean was assessed combining historic survey data (i.e. acoustic, ichthyoplankton, bottom trawl surveys) from five different areas along with satellite environmental and bathymetry data. Selected models were used to produce annual habitat suitability maps over the period 2000‐ 2 010 addressing different life stages (i.e. adults, juveniles and eggs) of the target species at a spatial resolution of 4x4 km. Based on these annual maps, habitat persistency maps were produced using GIS techniques where persistent and occasional locations suitable for nurseries and spawning grounds were identified. These areas are discussed in re lation to existing fishing restricted areas in the Mediterranean Sea.

Recent Advances in Environmental Science from the Euro-Mediterranean and Surrounding Regions (2nd Edition), 2021

Information integrated from different parts of the Mediterranean was used in order to model the s... more Information integrated from different parts of the Mediterranean was used in order to model the spatial and temporal variability of the distribution grounds of sardine. Acoustic data as recorded with a 38 kHz split beam echosounder from the Aegean Sea (Eastern Mediterranean), the Adriatic Sea (Central Mediterranean), the Sicily Channel (Central Mediterranean) and the Spanish waters (Western Mediterranean) have been analyzed along with satellite environmental and bathymetry data to model the spatial distribution of sardine during summer, autumn and early winter. Similarly, egg distribution data from the Spanish waters were used to model the potential spawning habitat of sardine during early winter. Satellite data were used as proxies to infer spatial variations of environmental factors and assess possible ecological relationships. Generalized Additive Models were applied in a presence/absence approach. Model results were evaluated based on the estimation of the area under the receive...

Regional Studies in Marine Science, 2021

Abstract Spatial management of discards has attracted increasing interest as a potential mitigati... more Abstract Spatial management of discards has attracted increasing interest as a potential mitigation measure. However, most studies are restricted to commercial species. The aim of the present work was to fill this gap by identifying and mapping the spatial distribution of five non-commercial species with high frequency of occurrence in the discarded catch of bottom trawl fishery in the Aegean Sea, i.e., Brown comber Serranus hepatus, Mediterranean scaldfish Arnoglossus laterna, Red bandfish Cepola macrophthalma, Argentine Argentina sphyraena, and Boarfish Capros aper. For this purpose, Generalized Additive Models were used to account for catch dependency on environmental parameters in order to explore the spatial distribution of species. Modeling results revealed that the spatial distribution of species was driven by environmental variables. Depth was the most informative variable explaining most catch variation in all species. For A. laterna, C. macrophthalma, and S. hepatus the highest estimated values of catch were located over the continental shelf and at shallower waters inside gulfs, whereas C. aper and A. sphyraena catch were more broadly distributed across the study area and at greater depths. Seasonal variations in species catch were also observed, probably related in most cases to species reproduction period. Mapping species distribution is essential for the identification of priority areas of protection in future marine spatial plans.

Fisheries Research, 2020

Abstract Discards is an important issue in fisheries around the world. The spatial management of ... more Abstract Discards is an important issue in fisheries around the world. The spatial management of discards has attracted interest as a potential tool for minimizing the unwanted catch. The aim of the present work was to identify areas with high quantities of bottom trawl discarded catch regarding species subjected to MCRS, in six areas of southern European waters (southern Portuguese waters, Catalan Sea, Ligurian and northern Tyrrhenian Seas, Strait of Sicily, eastern Ionian Sea, and Aegean Sea). Analyses were based on two types of data: (a) the undersized catch of species subjected to MCRS from bottom trawl surveys and (b) the actual discarded catch (including undersized and non-undersized individuals) of species subjected to MCRS from commercial bottom trawling. Geostatistical analysis techniques were applied to the first type of data and Generalized Additive Models using environmental variables were applied to the second one. Subsequently, areas that persistently presented high quantities of discarded catch (i.e., “iDC grounds”) or undersized catch (i.e., “iUC grounds”) were identified and mapped. The “iDC grounds”/“iUC grounds” were located either over the slope or within the continental shelf and over marine plateaus, largely depending on the main target species of each fishery. Next, the overlap of “iDC grounds”/“iUC grounds” with the existing Fisheries Restricted Areas (FRAs) and the proposed Marine Protected Areas (MPAs) was estimated aiming to explore how spatial closures could contribute to the reduction of bottom trawl discarded catch/undersized catch. Certain spatial closures were more effective in the Central Mediterranean and others to the Eastern Mediterranean. The overlapping of existing FRAs with “iDC grounds”/“iUC grounds” did not exceed 24 % in any study area, whereas proposed MPAs, like the CIESM Marine Peace Parks, reached up to 90 % for the same study area.

Mediterranean Marine Science, 2021

We present the development of a 3D full-lifecycle, individual-based model (IBM) for anchovy and s... more We present the development of a 3D full-lifecycle, individual-based model (IBM) for anchovy and sardine, online coupled to an existing hydrodynamic/biogeochemical low-trophic level (LTL) model for the North Aegean Sea. It was built upon an existing 1D model for the same species and area, with the addition of a horizontal movement scheme. In the model, both species evolve from the embryonic stage (egg+yolk sac larva) to the larval, juvenile, and adult stages. Somatic growth is simulated with the use of a “Wisconsin” type bioenergetics model and fish populations with an adaptation of the ‘super individuals’ (SI) approach. For the reference simulation and model calibration, in terms of fish growth and population biomass, the 2000-2010 period was selected. Interannual biomass variability of anchovy was successfully represented by the model, while the simulated biomass of sardine exhibited low variability and did not satisfactorily reproduce the observed interannual variability from acou...

Mediterranean Marine Science, 2021

The study of small pelagic fish by hydroacoustic methods in the Mediterranean Sea began in the A... more The study of small pelagic fish by hydroacoustic methods in the Mediterranean Sea began in the Adriatic in the 1950’s. Since 2009, internationally coordinated, extensive, regular surveys have been conducted in the framework of the MEDIAS - Mediterranean International Acoustic Surveys – action, under the EU Data Collection Framework, to provide inputs for the management of small pelagics, particularly European anchovy (Engraulis encrasicolus) and European sardine (Sardina pilchardus). The surveys cover EU Mediterranean waters and monitor the distribution and abundance of small pelagic species using a common protocol. The hydroacoustic surveys, historically conducted by each Country separately, have since been standardized and harmonized. This is a review of the evolution of the surveys from the beginning up to the present and discusses the future prospects. It reports the historical time series of anchovy, sardine and other small pelagics in different areas and describes the spatial...

Journal of Sea Research, 2018

Abstract The mitigation and incorporation of fisheries discards into the spatial management persp... more Abstract The mitigation and incorporation of fisheries discards into the spatial management perspective call for a well-planned approach considering their high spatiotemporal variability. This study describes an approach to map the spatiotemporal distribution of bottom trawl discards taking into account on-board observer data, environmental information and high-resolution estimates of fishing effort derived from Vessel Monitoring System data. Two were the main objectives: i) mapping the Discards Per Unit Effort (DPUE: kg/h) and ii) mapping the total discards quantities (in kg) in a predefined spatial unit (grid cell of 5 × 5 km). For this purpose, discards data from commercial bottom trawlers (seasonal basis, period 2003–2006, 2008) operating on the continental shelf of the eastern Ionian Sea were analyzed. The DPUE for a) all species with Minimum Landing Size (MLS), b) all species without MLS and c) all fish species, were modeled by means of Generalized Additive Models (GAMs) using satellite environmental parameters, bathymetry and season as independent covariates. Mapping discards quantities in a predefined spatial unit was based on the spatial overlapping between GAM estimates for the year 2010 and fishing effort distribution for the same year. Spatial clusters of high discard quantities (hot spots) and their spatiotemporal persistence were also investigated. Results revealed how the environmental and temporal factors influence the DPUE distribution of each discard group and indicated increased discards quantities in areas of high fishing effort. The potential implications of the resulting DPUE maps for advancing discards spatial mitigation are further discussed. Mapping discards quantities using both the DPUE and the fishing effort distribution provide valuable insights that can be useful to investigate the broader ecosystem consequences of the EU landing obligation and other potential fishery management policies.

Marine Ecology Progress Series, 2019

Under the general framework of existing recruitment hypotheses, knowledge on the drivers and mech... more Under the general framework of existing recruitment hypotheses, knowledge on the drivers and mechanisms involved in the determination of the year class strength of small pelagic fish (SPF) is briefly reviewed with focus on selected aspects of the adult and larval stages, related to breeding patterns, egg production, spawning habitats, reproductive potential and early life survival. An analysis of stock−recruitment time series data is carried out, showing that the maximum recruitment capacity of clupeoid stocks increases with the strength of temporal autocorrelation in recruitment (R) and decreases as the coefficient of variation of R becomes larger. Reproductive strategy in combination with the thermal and trophic conditions of the ecosystem and the life cycle pattern of the stock can influence the relative importance of high and low frequency variability in recruitment that combine to generate the population fluctuations of SPF. Selective fishing can reduce the reproductive potential and alter the spawning phenology of the stocks. To understand the ways by which the distribution, abundance and survival of larval stages are influenced by trophodynamic and physical factors, it is important to recognize all those milestones in fish ontogeny associated with significant changes in capabilities and behavior (e.g. onset of schooling). Temperature affects many parameters related to egg production and early life survival, but the relative importance of such temperature effects is expected to differ substantially in contrasting SPF habitats.