138
Figs 9,10 clearly shows this relationship, and the presence of bluefin tuna is noted in areas with
a current speed of 0.85 m/s. In the spring period, overabundances were found in water bodies
with an average current speed between 0.17 m/s and 0.3 m/s. In contrast to the summer period,
the current speed is very low, varying between 0.07 m/s and 0.15 m/s. (Arena, 1959a)when
investigating the influence of different factors on the catch of a tuna trap near Trapani, on the
west coast of Sicily, noted that low catches of bluefin tuna are associated with a south-westerly
current speed of 0.49 m/sec, while the best catches were made in areas with a north-easterly
current speed of 0.73 m/sec. The coefficient of variation is 0.60 Table 1, which means that the
distribution of current speed values is heterogeneous. In fact, bluefin tuna have the ability to
live in an environment of great variability with respect to the speed of the sea current.
Fig. 9. Seasonal variations in bluefin tuna abundances in relation to environmental factors:
Chlorophyll a, Current speed, Wave height, and nitrate (NO3).
The distribution of bluefin tuna is related to the oceanic front for several reasons: either for food
needs, as oceanic fronts are favoured areas for energy transfer along trophic chains (Royer,
2005e); or for migration needs, as they are able to associate with the limits of the Gulf Stream
current so that they can distribute in the European territory on the North Atlantic side (Lehodey
et al., 1997); or for breeding requirements, as anticyclonic eddies or frontal areas are potentially
favourable for the survival and development of eggs and larvae (Bakun, 1996b) (García et al.,
2003b).
2000-Tr2 2000-Tr3 2001-Tr2 2001-Tr3 2002-Tr2 2002-Tr3 2003-Tr2
2003Tr3 2004-Tr2 2004-Tr3 2004-Tr4
2005-Tr2 2005-Tr4 2005-Tr1
2005-Tr3 2006-Tr2 2006-Tr3 2006-Tr4 2007-Tr2 2007-Tr1 2007-Tr4 2007-Tr3 2008-Tr2 2008-Tr3 2009-Tr2 2009-Tr3 2010-Tr3 2011-Tr4 2011-Tr2 2011-Tr3 2012-Tr1 2012-Tr2 2012-Tr4 2012-Tr3 2013-Tr2 2013-Tr4 2013-Tr3 2013-Tr1 2014-Tr2 2014-Tr4 2014-Tr1 2014-Tr3 2015-Tr1 2015-Tr2 2015-Tr4 2015-Tr3 2016-Tr4 2016-Tr1 2016-Tr2 2016-Tr3 2017-Tr1 2017-Tr4 2017-Tr3 2017-Tr2 2018-Tr4 2018-Tr1 2018-Tr2 2018-Tr3 2019-Tr1 2019-Tr3 2019-Tr2
0,00
0,50
1,00
1,50
2,00
2,50
3,00
3,50
4,00
0
500
1000
1500
2000
2500
3000
3500
Time (trimestre)
Values
A
b
u
n
d
a
n
c
e
s
Abundance
Chl a (mg.m-3)
NO3 (mmol.m-3)
Crrt spd (m/s)
Wave height (m)
0,02
0,12
0,22
0,32
0,42
0,52
0,62
0,72
257,5 256,0 226,0 219,8 233,8 221,3
218,8 163,8
181,7 146,9
179,3 171,5 155,9 237,5 233,2 171,0 160,0 247,5 187,0 223,6 233,8 205,0 205,0 185,5 230,8 226,1 220,3
225,3
255,1 226,0 229,0 142,6 225,8 227,8 221,3 251,3 227,1 226,6 237,1 231,2 221,3 227,5 224,5
244,4 215,0 231,7 181,1 230,7 223,7 237,5 227,5 296,4
228,0 258,0 260,2 254,6 230,6 245,0 162,5 218,7 169,3
0
500
1000
1500
2000
2500
3000
3500
2004-Tr4 2005-Tr1 2007-Tr1 2018-Tr1 2004-Tr3 2014-Tr4
2007-Tr2_w 2017-Tr1 2007-Tr2
2004-Tr2_w 2001-Tr2 2009-Tr2
2001-Tr2_w 2003-Tr2_w 2003-Tr2 2004-Tr2 2008-Tr2 2007-Tr3 2013-Tr4 2002-Tr2 2006-Tr2 2013-Tr1 2018-Tr4 2016-Tr4 2014-Tr3 2002-Tr3 2015-Tr1 2000-Tr2 2014-Tr1 2011-Tr4 2015-Tr2
2000-Tr2_w 2006-Tr3
2002-Tr2_w 2011-Tr3 2017-Tr3 2012-Tr4 2005-Tr2 2016-Tr1 2015-Tr3 2015-Tr4 2010-Tr3 2017-Tr2 2016-Tr2 2018-Tr3 2016-Tr3 2013-Tr2 2012-Tr2 2018-Tr2
2013-Tr3 2000-Tr3 2009-Tr3 2014-Tr2 2012-Tr3 2017-Tr4 2011-Tr2 2012-Tr1 2006-Tr4
2001-Tr3
2003Tr3 2005-Tr3 2005-Tr4 2007-Tr4 2008-Tr3 2019-Tr1 2019-Tr2 2019-Tr3
Current
speed
(m/s)
Time (trimester)
Abundance
Lt (cm)
Abundance
Crrt spd (m/s)
Figs 9,10 clearly shows this relationship, and the presence of bluefin tuna is noted in areas with
a current speed of 0.85 m/s. In the spring period, overabundances were found in water bodies
with an average current speed between 0.17 m/s and 0.3 m/s. In contrast to the summer period,
the current speed is very low, varying between 0.07 m/s and 0.15 m/s. (Arena, 1959a)when
investigating the influence of different factors on the catch of a tuna trap near Trapani, on the
west coast of Sicily, noted that low catches of bluefin tuna are associated with a south-westerly
current speed of 0.49 m/sec, while the best catches were made in areas with a north-easterly
current speed of 0.73 m/sec. The coefficient of variation is 0.60 Table 1, which means that the
distribution of current speed values is heterogeneous. In fact, bluefin tuna have the ability to
live in an environment of great variability with respect to the speed of the sea current.
Fig. 9. Seasonal variations in bluefin tuna abundances in relation to environmental factors:
Chlorophyll a, Current speed, Wave height, and nitrate (NO3).
The distribution of bluefin tuna is related to the oceanic front for several reasons: either for food
needs, as oceanic fronts are favoured areas for energy transfer along trophic chains (Royer,
2005e); or for migration needs, as they are able to associate with the limits of the Gulf Stream
current so that they can distribute in the European territory on the North Atlantic side (Lehodey
et al., 1997); or for breeding requirements, as anticyclonic eddies or frontal areas are potentially
favourable for the survival and development of eggs and larvae (Bakun, 1996b) (García et al.,
2003b).
2000-Tr2 2000-Tr3 2001-Tr2 2001-Tr3 2002-Tr2 2002-Tr3 2003-Tr2
2003Tr3 2004-Tr2 2004-Tr3 2004-Tr4
2005-Tr2 2005-Tr4 2005-Tr1
2005-Tr3 2006-Tr2 2006-Tr3 2006-Tr4 2007-Tr2 2007-Tr1 2007-Tr4 2007-Tr3 2008-Tr2 2008-Tr3 2009-Tr2 2009-Tr3 2010-Tr3 2011-Tr4 2011-Tr2 2011-Tr3 2012-Tr1 2012-Tr2 2012-Tr4 2012-Tr3 2013-Tr2 2013-Tr4 2013-Tr3 2013-Tr1 2014-Tr2 2014-Tr4 2014-Tr1 2014-Tr3 2015-Tr1 2015-Tr2 2015-Tr4 2015-Tr3 2016-Tr4 2016-Tr1 2016-Tr2 2016-Tr3 2017-Tr1 2017-Tr4 2017-Tr3 2017-Tr2 2018-Tr4 2018-Tr1 2018-Tr2 2018-Tr3 2019-Tr1 2019-Tr3 2019-Tr2
0,00
0,50
1,00
1,50
2,00
2,50
3,00
3,50
4,00
0
500
1000
1500
2000
2500
3000
3500
Time (trimestre)
Values
A
b
u
n
d
a
n
c
e
s
Abundance
Chl a (mg.m-3)
NO3 (mmol.m-3)
Crrt spd (m/s)
Wave height (m)
0,02
0,12
0,22
0,32
0,42
0,52
0,62
0,72
257,5 256,0 226,0 219,8 233,8 221,3
218,8 163,8
181,7 146,9
179,3 171,5 155,9 237,5 233,2 171,0 160,0 247,5 187,0 223,6 233,8 205,0 205,0 185,5 230,8 226,1 220,3
225,3
255,1 226,0 229,0 142,6 225,8 227,8 221,3 251,3 227,1 226,6 237,1 231,2 221,3 227,5 224,5
244,4 215,0 231,7 181,1 230,7 223,7 237,5 227,5 296,4
228,0 258,0 260,2 254,6 230,6 245,0 162,5 218,7 169,3
0
500
1000
1500
2000
2500
3000
3500
2004-Tr4 2005-Tr1 2007-Tr1 2018-Tr1 2004-Tr3 2014-Tr4
2007-Tr2_w 2017-Tr1 2007-Tr2
2004-Tr2_w 2001-Tr2 2009-Tr2
2001-Tr2_w 2003-Tr2_w 2003-Tr2 2004-Tr2 2008-Tr2 2007-Tr3 2013-Tr4 2002-Tr2 2006-Tr2 2013-Tr1 2018-Tr4 2016-Tr4 2014-Tr3 2002-Tr3 2015-Tr1 2000-Tr2 2014-Tr1 2011-Tr4 2015-Tr2
2000-Tr2_w 2006-Tr3
2002-Tr2_w 2011-Tr3 2017-Tr3 2012-Tr4 2005-Tr2 2016-Tr1 2015-Tr3 2015-Tr4 2010-Tr3 2017-Tr2 2016-Tr2 2018-Tr3 2016-Tr3 2013-Tr2 2012-Tr2 2018-Tr2
2013-Tr3 2000-Tr3 2009-Tr3 2014-Tr2 2012-Tr3 2017-Tr4 2011-Tr2 2012-Tr1 2006-Tr4
2001-Tr3
2003Tr3 2005-Tr3 2005-Tr4 2007-Tr4 2008-Tr3 2019-Tr1 2019-Tr2 2019-Tr3
Current
speed
(m/s)
Time (trimester)
Abundance
Lt (cm)
Abundance
Crrt spd (m/s)