129
Introduction
The Atlantic bluefin tuna (Thunnus thynnus) is a valuable species,(Garcia and Gordon,
1992 ; Durrieu de Madron et al., 2011); and one of the most important fisheries resources in
the Mediterranean Sea.
The distribution of the Atlantic bluefin tuna (thunnus thynnus), extends from the North Atlantic
Ocean to its adjacent seas, in particular the Mediterranean (d’Ortenzio and Ribera d’Alcalà,
2009) , from Gibraltar to the Black Sea. (COMP, 1950).
The bluefin tuna have been studied since ancient times and have been considered a great
migrator. However, over the last ten years, new research using tagging techniques has advanced
the issue and shown that the tuna is capable of even greater movements than previously
thought(Lutcavage et al., 2000a).
Bluefin tuna is also a shared resource, with high economic value and exploited on an oceanwide scale by some 20 countries including Algeria. The quota granted to Algeria has been
increasing exponentially over the last decade, in 2000 it was 130 tonnes and in 2019 it reached
1437 tonnes (“ICCAT·CICTA·CICAA,” 2019), despite this, few scientific works interested in
this species during the last decade, only six works along the Algerian coast namely (Neghli and
Nouar, 2014 ; Labidi and Nouar (2013a , 2013b) ; Abdelhadi et al., 2011; (Nouar and
Labidi, 2009).
In this study, we integrate geo-referenced fisheries data with remotely sensed oceanographic
datasets to answer our questions, How does the environment contribute to the temporal
distribution of bluefin tuna? We determined the conditions favourable to the temporal
distribution of Thunnus thynnus, Bluefin Tuna (BFT) ; What are the environmental
determinants that contribute to the temporal distribution of bluefin tuna along the Algerian coast
?
Changes in temperature, salinity, wind field and currents can affect the productivity and
distribution of fish stocks (e.g. (Gushing and Dickson, 1977); Southward et al., 1988;
(Dickson and Brander, 1993); (Lehodey et al., 1997);(Alheit and Hagen, 2001)).
This tuna-environment research has three objectives: i) to understand the behaviour and
distribution of tuna in the face of variability in environmental factors, ii) to assist the scientist
in the management of the stocks, and iii) to assist fishermen to fish their quotas in the short
term and to assist the competent authorities in controlling the fishermen.
Materials and methods
Study Area
Algeria has a coastline of about 1622 km (Kacemi, 2013), from the Algerian-Moroccan border
in the west to the Algerian-Tunisian border in the east.
Fig.1 shows the geographical limits of the study area and the sampling sites using the fishing
gear (long surface longline). The study area is located in the southwestern part of the
Mediterranean, the central and eastern part of the Algerian coast, between Ténès in the west
and the Algerian-Tunisian border in the east.
Introduction
The Atlantic bluefin tuna (Thunnus thynnus) is a valuable species,(Garcia and Gordon,
1992 ; Durrieu de Madron et al., 2011); and one of the most important fisheries resources in
the Mediterranean Sea.
The distribution of the Atlantic bluefin tuna (thunnus thynnus), extends from the North Atlantic
Ocean to its adjacent seas, in particular the Mediterranean (d’Ortenzio and Ribera d’Alcalà,
2009) , from Gibraltar to the Black Sea. (COMP, 1950).
The bluefin tuna have been studied since ancient times and have been considered a great
migrator. However, over the last ten years, new research using tagging techniques has advanced
the issue and shown that the tuna is capable of even greater movements than previously
thought(Lutcavage et al., 2000a).
Bluefin tuna is also a shared resource, with high economic value and exploited on an oceanwide scale by some 20 countries including Algeria. The quota granted to Algeria has been
increasing exponentially over the last decade, in 2000 it was 130 tonnes and in 2019 it reached
1437 tonnes (“ICCAT·CICTA·CICAA,” 2019), despite this, few scientific works interested in
this species during the last decade, only six works along the Algerian coast namely (Neghli and
Nouar, 2014 ; Labidi and Nouar (2013a , 2013b) ; Abdelhadi et al., 2011; (Nouar and
Labidi, 2009).
In this study, we integrate geo-referenced fisheries data with remotely sensed oceanographic
datasets to answer our questions, How does the environment contribute to the temporal
distribution of bluefin tuna? We determined the conditions favourable to the temporal
distribution of Thunnus thynnus, Bluefin Tuna (BFT) ; What are the environmental
determinants that contribute to the temporal distribution of bluefin tuna along the Algerian coast
?
Changes in temperature, salinity, wind field and currents can affect the productivity and
distribution of fish stocks (e.g. (Gushing and Dickson, 1977); Southward et al., 1988;
(Dickson and Brander, 1993); (Lehodey et al., 1997);(Alheit and Hagen, 2001)).
This tuna-environment research has three objectives: i) to understand the behaviour and
distribution of tuna in the face of variability in environmental factors, ii) to assist the scientist
in the management of the stocks, and iii) to assist fishermen to fish their quotas in the short
term and to assist the competent authorities in controlling the fishermen.
Materials and methods
Study Area
Algeria has a coastline of about 1622 km (Kacemi, 2013), from the Algerian-Moroccan border
in the west to the Algerian-Tunisian border in the east.
Fig.1 shows the geographical limits of the study area and the sampling sites using the fishing
gear (long surface longline). The study area is located in the southwestern part of the
Mediterranean, the central and eastern part of the Algerian coast, between Ténès in the west
and the Algerian-Tunisian border in the east.