SUMMARY Preliminary results of tuna larval surveys conducted off different Mediterranean regions ... more SUMMARY Preliminary results of tuna larval surveys conducted off different Mediterranean regions during the 2004 bluefin spawning season are presented. Data on bluefin and other tuna species larval catches are reported from the Balearic Sea, the Levantine Sea and the Sicilian coasts. The Balearic Sea showed the highest bluefin larval catch which are clearly associated to surface temperatures within the
ABSTRACT The distribution, abundance, and interannual variation of scyllarid phyllosoma larvae we... more ABSTRACT The distribution, abundance, and interannual variation of scyllarid phyllosoma larvae were studied in waters of the Balearic Sea (Western Mediterranean) from plankton samples collected between 2001 and 2005. Over the study period, 342 phyllosomas were collected, all belonging to Scyllaridae. Scyllarus arctus (Linnaeus, 1758) was the most abundant (89%), with representation of all developmental stages (I-X), except stage IX, plus two nistos. Scyllarus pygmaeus (Bate, 1888) phyllosoma included middle stages (IV-VII) and two final stages X. Finally, a stage II phyllosoma of Scyllarides latus (Latreille, 1802) was recorded for the first time in the Western Mediterranean. The majority of the phyllosomas were early stage S. arctus found in near shore stations, while advanced stages were common farther away from the coast, especially to the south of the Balearic Sea. That was also the case of S. pygmaeus, most of which stage V, observed to the southwest of the archipelago. Phyllosomas were scarce in low salinity (S < 37.2) water masses of recent Atlantic origin, and interannual differences in distribution reflected the intrusions of low salinity Atlantic water from the South.
ABSTRACT Despite being well adapted for feeding in cold water on their North Atlantic feeding gro... more ABSTRACT Despite being well adapted for feeding in cold water on their North Atlantic feeding grounds, Atlantic bluefin tuna undertake long migrations to reach warm, low productivity spawning grounds in the Gulf of Mexico and Mediterranean Sea. Environmental conditions within spawning areas have been presumed to benefit larval survival, through appropriate feeding conditions, and enhanced larval retention and growth rates. However, field collections and studies to explore the potential mechanisms are rare. In this study, a comparison of the environmental characteristics of both spawning sites was completed using standardized environmental data and modeling methods. Predictive models of larval occurrence were constructed using historical larval collections, and environmental variables from both in situ and remotely sensed sources. Results showed that larvae on both spawning grounds were most likely to be found in warm (23 to 28 degrees C), low chlorophyll areas with moderate current velocities and favorable regional retention conditions. In the Gulf of Mexico, larvae were located in offshore waters outside of the Loop Current and warm eddies, while in the western Mediterranean, larval occurrences were associated with the confluence of inflowing Atlantic waters and saltier resident surface waters. Although our results suggested common themes within preferred spawning grounds on both sides of the Atlantic Ocean, the ecological processes governing larval survival and eventual recruitment are yet to be fully understood.
ABSTRACT An intense oceanic front was detected at the west of Mallorca Island (Balearic sub-basin... more ABSTRACT An intense oceanic front was detected at the west of Mallorca Island (Balearic sub-basin of the North Western Mediterranean Sea) during an oceanographic survey in December 2009. This contribution analyses the hydrography and geostrophic motions observed at the front, together with the ageostrophic motion derived from the omega equation. The front separated resident Atlantic water (to the north) from more recent Atlantic water (to the south). Maximum upward vertical velocities of 6 m/day were found at the northern side of the front, related with relative maxima of dissolved oxygen and fluorescence. The vertical velocities in this study are mainly due to relative vorticity advection. AVISO altimetry data is used to discuss the advection of the front over a nearby mooring equipped with temperature and salinity sensors at 300 m below the sea surface. The biological implications of the front are discussed by means of acoustic backscatter data. There is an observed increase in mesopelagic fish biomass at the frontal area. Our hypothesis states that the vertical velocities associated to the front would lead to the observed increase in mesopelagic biomass near the front, which is in agreement with previous studies in other frontal systems.
The research reported in this paper is part of the activities carried out within the CLARIN proje... more The research reported in this paper is part of the activities carried out within the CLARIN project. CLARIN is a large-scale pan-European project devoted to the creation of a persistent and stable network serving the needs of the European Humanities and Social ...
SUMMARY Preliminary results of tuna larval surveys conducted off different Mediterranean regions ... more SUMMARY Preliminary results of tuna larval surveys conducted off different Mediterranean regions during the 2004 bluefin spawning season are presented. Data on bluefin and other tuna species larval catches are reported from the Balearic Sea, the Levantine Sea and the Sicilian coasts. The Balearic Sea showed the highest bluefin larval catch which are clearly associated to surface temperatures within the
ABSTRACT The distribution, abundance, and interannual variation of scyllarid phyllosoma larvae we... more ABSTRACT The distribution, abundance, and interannual variation of scyllarid phyllosoma larvae were studied in waters of the Balearic Sea (Western Mediterranean) from plankton samples collected between 2001 and 2005. Over the study period, 342 phyllosomas were collected, all belonging to Scyllaridae. Scyllarus arctus (Linnaeus, 1758) was the most abundant (89%), with representation of all developmental stages (I-X), except stage IX, plus two nistos. Scyllarus pygmaeus (Bate, 1888) phyllosoma included middle stages (IV-VII) and two final stages X. Finally, a stage II phyllosoma of Scyllarides latus (Latreille, 1802) was recorded for the first time in the Western Mediterranean. The majority of the phyllosomas were early stage S. arctus found in near shore stations, while advanced stages were common farther away from the coast, especially to the south of the Balearic Sea. That was also the case of S. pygmaeus, most of which stage V, observed to the southwest of the archipelago. Phyllosomas were scarce in low salinity (S < 37.2) water masses of recent Atlantic origin, and interannual differences in distribution reflected the intrusions of low salinity Atlantic water from the South.
ABSTRACT Despite being well adapted for feeding in cold water on their North Atlantic feeding gro... more ABSTRACT Despite being well adapted for feeding in cold water on their North Atlantic feeding grounds, Atlantic bluefin tuna undertake long migrations to reach warm, low productivity spawning grounds in the Gulf of Mexico and Mediterranean Sea. Environmental conditions within spawning areas have been presumed to benefit larval survival, through appropriate feeding conditions, and enhanced larval retention and growth rates. However, field collections and studies to explore the potential mechanisms are rare. In this study, a comparison of the environmental characteristics of both spawning sites was completed using standardized environmental data and modeling methods. Predictive models of larval occurrence were constructed using historical larval collections, and environmental variables from both in situ and remotely sensed sources. Results showed that larvae on both spawning grounds were most likely to be found in warm (23 to 28 degrees C), low chlorophyll areas with moderate current velocities and favorable regional retention conditions. In the Gulf of Mexico, larvae were located in offshore waters outside of the Loop Current and warm eddies, while in the western Mediterranean, larval occurrences were associated with the confluence of inflowing Atlantic waters and saltier resident surface waters. Although our results suggested common themes within preferred spawning grounds on both sides of the Atlantic Ocean, the ecological processes governing larval survival and eventual recruitment are yet to be fully understood.
ABSTRACT An intense oceanic front was detected at the west of Mallorca Island (Balearic sub-basin... more ABSTRACT An intense oceanic front was detected at the west of Mallorca Island (Balearic sub-basin of the North Western Mediterranean Sea) during an oceanographic survey in December 2009. This contribution analyses the hydrography and geostrophic motions observed at the front, together with the ageostrophic motion derived from the omega equation. The front separated resident Atlantic water (to the north) from more recent Atlantic water (to the south). Maximum upward vertical velocities of 6 m/day were found at the northern side of the front, related with relative maxima of dissolved oxygen and fluorescence. The vertical velocities in this study are mainly due to relative vorticity advection. AVISO altimetry data is used to discuss the advection of the front over a nearby mooring equipped with temperature and salinity sensors at 300 m below the sea surface. The biological implications of the front are discussed by means of acoustic backscatter data. There is an observed increase in mesopelagic fish biomass at the frontal area. Our hypothesis states that the vertical velocities associated to the front would lead to the observed increase in mesopelagic biomass near the front, which is in agreement with previous studies in other frontal systems.
The research reported in this paper is part of the activities carried out within the CLARIN proje... more The research reported in this paper is part of the activities carried out within the CLARIN project. CLARIN is a large-scale pan-European project devoted to the creation of a persistent and stable network serving the needs of the European Humanities and Social ...
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