(i.e. Isurus oxyrinchus and Lamna nasus), and thresher sharks. The abundance of all
these five species has declined by between 96% and 99.99%. According to the
International Union for the Conservation of Nature (IUCN) criteria, these species
would be considered critically endangered (Ferretti et al. 2008). These pelagic sharks
are bycaught in the northern and southern Alboran Sea. The highest rate of bycatch is
caused by the use of surface longlines; on rare occasions, they are bycaught by
trawlers (Mohammed 2004; Báez et al. 2009). For decades, these species also have
been targeted by Spanish and Moroccan driftnet fisheries in the Alboran Sea (Tudela
et al. 2005 and references therein).
Unlike the northern Moroccan longline fleet, the longline fleet operating in the
north Alboran Sea has lost its pure artisanal character. The most important homebased harbour for the surface longline fleet operating in the Alboran Sea is
Carboneras (Almeria), a port situated in the northeastern area of the Alboran Sea.
This harbour hosts a large surface longline fleet targeting swordfish (Xiphias
gladius). The fleet also operates in the western Mediterranean Sea and the Canary
Islands. The harbour of Roquetas de Mar (Almeria) also has a large fleet of artisanal
surface longliners that operate in the north Alboran Sea. In Morocco, the most
important fleet targeting blackspot seabream Pagellus bogaraveo are the longliners
based at Tangier and the artisanal fleet operating in the area of the Strait of Gibraltar.
In recent years, the Moroccan longliner fleet has been more or less stable (around
98 vessels), whereas between 2009 and 2011, there was an increase in the size of the
artisanal fleet (CopeMed II 2012). The pelagic waters situated over the submarine
canyons near to Motril (Fig. 21.1a) are the most important fishing area in the Alboran
Sea for Spanish drifting longliners targeting swordfish. For some months, they also
target blue shark. Bycatch by this fishery includes birds, marine mammals, and
turtles (Fig. 21.2).
Between 1999 and 2002, the amount of shark caught in the Alboran Sea by the
Spanish surface longline fleet was 34.3% of the total weight of the sampled catches.
This is the highest percentage of all incidental shark catch in the Mediterranean Sea
(Valeiras et al. 2003; Macías et al. 2004; Megalofonou et al. 2005b) and could be
related to the location, which is an important migratory channel adjacent to the
Atlantic Ocean (Megalofonou et al. 2005b). The higher frequency of sharks in the
Alboran Sea could also be due to the higher trophic potential of the western
Mediterranean compared to the eastern part. The highest shark catch has been
observed in the swordfish longline fishery in the Alboran Sea, where the nominal
catch per unit effort (CPUE) was 3.8 sharks/1000 hooks.
Between 2000 and 2012, blue sharks were the most-caught species in the northern
Alboran Sea (Fig. 21.3). Between 1999 and 2001, blue shark bycatch by the Spanish
surface longline fisheries targeting swordfish was 2% of the total catch. Information
collected from onboard observers during 861 fishing sets in 26 longliners operating
in the western Mediterranean Sea indicated that the greatest bycatches were taken in
the Alboran Sea, representing 75.6% of the total observed bycatch of blue shark. The
observed CPUE ranged from 5.5 to 34.1 kg/1000 hooks. The mean length at capture
21 Marine Megafauna and Charismatic Vertebrate Species
711
these five species has declined by between 96% and 99.99%. According to the
International Union for the Conservation of Nature (IUCN) criteria, these species
would be considered critically endangered (Ferretti et al. 2008). These pelagic sharks
are bycaught in the northern and southern Alboran Sea. The highest rate of bycatch is
caused by the use of surface longlines; on rare occasions, they are bycaught by
trawlers (Mohammed 2004; Báez et al. 2009). For decades, these species also have
been targeted by Spanish and Moroccan driftnet fisheries in the Alboran Sea (Tudela
et al. 2005 and references therein).
Unlike the northern Moroccan longline fleet, the longline fleet operating in the
north Alboran Sea has lost its pure artisanal character. The most important homebased harbour for the surface longline fleet operating in the Alboran Sea is
Carboneras (Almeria), a port situated in the northeastern area of the Alboran Sea.
This harbour hosts a large surface longline fleet targeting swordfish (Xiphias
gladius). The fleet also operates in the western Mediterranean Sea and the Canary
Islands. The harbour of Roquetas de Mar (Almeria) also has a large fleet of artisanal
surface longliners that operate in the north Alboran Sea. In Morocco, the most
important fleet targeting blackspot seabream Pagellus bogaraveo are the longliners
based at Tangier and the artisanal fleet operating in the area of the Strait of Gibraltar.
In recent years, the Moroccan longliner fleet has been more or less stable (around
98 vessels), whereas between 2009 and 2011, there was an increase in the size of the
artisanal fleet (CopeMed II 2012). The pelagic waters situated over the submarine
canyons near to Motril (Fig. 21.1a) are the most important fishing area in the Alboran
Sea for Spanish drifting longliners targeting swordfish. For some months, they also
target blue shark. Bycatch by this fishery includes birds, marine mammals, and
turtles (Fig. 21.2).
Between 1999 and 2002, the amount of shark caught in the Alboran Sea by the
Spanish surface longline fleet was 34.3% of the total weight of the sampled catches.
This is the highest percentage of all incidental shark catch in the Mediterranean Sea
(Valeiras et al. 2003; Macías et al. 2004; Megalofonou et al. 2005b) and could be
related to the location, which is an important migratory channel adjacent to the
Atlantic Ocean (Megalofonou et al. 2005b). The higher frequency of sharks in the
Alboran Sea could also be due to the higher trophic potential of the western
Mediterranean compared to the eastern part. The highest shark catch has been
observed in the swordfish longline fishery in the Alboran Sea, where the nominal
catch per unit effort (CPUE) was 3.8 sharks/1000 hooks.
Between 2000 and 2012, blue sharks were the most-caught species in the northern
Alboran Sea (Fig. 21.3). Between 1999 and 2001, blue shark bycatch by the Spanish
surface longline fisheries targeting swordfish was 2% of the total catch. Information
collected from onboard observers during 861 fishing sets in 26 longliners operating
in the western Mediterranean Sea indicated that the greatest bycatches were taken in
the Alboran Sea, representing 75.6% of the total observed bycatch of blue shark. The
observed CPUE ranged from 5.5 to 34.1 kg/1000 hooks. The mean length at capture
21 Marine Megafauna and Charismatic Vertebrate Species
711