Jghab Ayman - Academia.edu (original) (raw)

Papers by Jghab Ayman

Journal of Marine Systems, 2018

Abstract The study of environmental variables and their influence on the small pelagic fish stock... more Abstract The study of environmental variables and their influence on the small pelagic fish stocks of the Alboran Sea (Western Mediterranean) is asymmetrical, with studies focused on the southern coast being scarce compared with those looking at the northern margin. In this work, time series of sardine landings from the Moroccan coast of the Alboran Sea from 1981 to 2016 were analyzed together with environmental variables such as Sea Surface Temperature (SST), Sea Surface Salinity (SSS), Surface Chlorophyll-a concentrations (Chl-a), and the velocity of the Atlantic Jet (AJ) flowing into the Mediterranean Sea through the Strait of Gibraltar. Annual sardine catches decreased from 1981 to 2016 at a rate of −258 t/year. At the same time, the SST and SSS increased at rates of 0.03 °C/year and 0.004 ups/year, respectively, very likely as a result of climate change. Linear models reflect a negative relationship between sardine landings and SST and SSS, indicating that the long-term temperature and salinity changes in the Mediterranean could have a negative impact on sardine abundance. At an inter-annual time scale, chlorophyll concentrations seem to be positively related to sardine abundances. A decrease in the kinetic energy of the AJ is also inferred from the cross-strait sea level difference (SLD). This variable has an important influence (positive correlation) on sardine landings, both in the long term and at the inter-annual time scale, with higher sardine abundances associated to higher SLD. This work shows that environmental variables such as SLD, SST, SSS, and Chl-a are the main driving factors for the variability of sardine landings in the southern Alboran Sea.

The influence of environmental factors and hydrodynamics on sardine (Sardina pilchardus, Walbaum 1792) abundance in the southern Alboran Sea, 2019

The study of environmental variables and their influence on the small pelagic fish stocks of the ... more The study of environmental variables and their influence on the small pelagic fish stocks of the Alboran Sea
(Western Mediterranean) is asymmetrical, with studies focused on the southern coast being scarce compared
with those looking at the northern margin. In this work, time series of sardine landings from the Moroccan coast
of the Alboran Sea from 1981 to 2016 were analyzed together with environmental variables such as Sea Surface
Temperature (SST), Sea Surface Salinity (SSS), Surface Chlorophyll-a concentrations (Chl-a), and the velocity of
the Atlantic Jet (AJ) flowing into the Mediterranean Sea through the Strait of Gibraltar. Annual sardine catches
decreased from 1981 to 2016 at a rate of −258 t/year. At the same time, the SST and SSS increased at rates of
0.03 °C/year and 0.004 ups/year, respectively, very likely as a result of climate change. Linear models reflect a
negative relationship between sardine landings and SST and SSS, indicating that the long-term temperature and
salinity changes in the Mediterranean could have a negative impact on sardine abundance. At an inter-annual
time scale, chlorophyll concentrations seem to be positively related to sardine abundances. A decrease in the
kinetic energy of the AJ is also inferred from the cross-strait sea level difference (SLD). This variable has an
important influence (positive correlation) on sardine landings, both in the long term and at the inter-annual time
scale, with higher sardine abundances associated to higher SLD. This work shows that environmental variables
such as SLD, SST, SSS, and Chl-a are the main driving factors for the variability of sardine landings in the
southern Alboran Sea.

Journal of Marine Systems, 2018

Abstract The study of environmental variables and their influence on the small pelagic fish stock... more Abstract The study of environmental variables and their influence on the small pelagic fish stocks of the Alboran Sea (Western Mediterranean) is asymmetrical, with studies focused on the southern coast being scarce compared with those looking at the northern margin. In this work, time series of sardine landings from the Moroccan coast of the Alboran Sea from 1981 to 2016 were analyzed together with environmental variables such as Sea Surface Temperature (SST), Sea Surface Salinity (SSS), Surface Chlorophyll-a concentrations (Chl-a), and the velocity of the Atlantic Jet (AJ) flowing into the Mediterranean Sea through the Strait of Gibraltar. Annual sardine catches decreased from 1981 to 2016 at a rate of −258 t/year. At the same time, the SST and SSS increased at rates of 0.03 °C/year and 0.004 ups/year, respectively, very likely as a result of climate change. Linear models reflect a negative relationship between sardine landings and SST and SSS, indicating that the long-term temperature and salinity changes in the Mediterranean could have a negative impact on sardine abundance. At an inter-annual time scale, chlorophyll concentrations seem to be positively related to sardine abundances. A decrease in the kinetic energy of the AJ is also inferred from the cross-strait sea level difference (SLD). This variable has an important influence (positive correlation) on sardine landings, both in the long term and at the inter-annual time scale, with higher sardine abundances associated to higher SLD. This work shows that environmental variables such as SLD, SST, SSS, and Chl-a are the main driving factors for the variability of sardine landings in the southern Alboran Sea.

The influence of environmental factors and hydrodynamics on sardine (Sardina pilchardus, Walbaum 1792) abundance in the southern Alboran Sea, 2019

The study of environmental variables and their influence on the small pelagic fish stocks of the ... more The study of environmental variables and their influence on the small pelagic fish stocks of the Alboran Sea
(Western Mediterranean) is asymmetrical, with studies focused on the southern coast being scarce compared
with those looking at the northern margin. In this work, time series of sardine landings from the Moroccan coast
of the Alboran Sea from 1981 to 2016 were analyzed together with environmental variables such as Sea Surface
Temperature (SST), Sea Surface Salinity (SSS), Surface Chlorophyll-a concentrations (Chl-a), and the velocity of
the Atlantic Jet (AJ) flowing into the Mediterranean Sea through the Strait of Gibraltar. Annual sardine catches
decreased from 1981 to 2016 at a rate of −258 t/year. At the same time, the SST and SSS increased at rates of
0.03 °C/year and 0.004 ups/year, respectively, very likely as a result of climate change. Linear models reflect a
negative relationship between sardine landings and SST and SSS, indicating that the long-term temperature and
salinity changes in the Mediterranean could have a negative impact on sardine abundance. At an inter-annual
time scale, chlorophyll concentrations seem to be positively related to sardine abundances. A decrease in the
kinetic energy of the AJ is also inferred from the cross-strait sea level difference (SLD). This variable has an
important influence (positive correlation) on sardine landings, both in the long term and at the inter-annual time
scale, with higher sardine abundances associated to higher SLD. This work shows that environmental variables
such as SLD, SST, SSS, and Chl-a are the main driving factors for the variability of sardine landings in the
southern Alboran Sea.