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Eastern Atlantic and Mediterranean bluefin tuna populations 1307
(b)
10
8
6 1600 1650 1700 1750 1800 1850 1900 1950
Saline
4
1550
10
8
Number of tuna (log) 6 Porto Scuso 1650 1700 1750 1800 1850 1900 1950
1550 1600
10
8
Medo das Casas
6 1600 1650 1700 1750 1800 1850 1900 1950
1550
10
8
6 Sidi Daoud
1550 1600 1650 1700 1750 1800 1850 1900 1950
11
10
9
Barbate
8
1550 1600 1650 1700 1750 1800 1850 1900 1950
Year
Figure 5b.
Figure 5. Examples of 12 time-series of trap catches (thin lines, log data; bold lines, smoothed data). (a) Catches of the three longest
Sicilian (‘‘Formica’’, ‘‘Favignana’’, ‘‘Bonagia’’) and two longest Spanish (‘‘Conil’’, ‘‘Zahara’’) time-series. For the two latter, the
time of change in gear from beach-seine to trap is indicated by the arrow (1804 for ‘‘Zahara’’, and 1806–1809 for ‘‘Conil’’).
(b) Catches of two Sardinian (‘‘Saline’’ and ‘‘Porto Scuso’’), one Portuguese (‘‘Medo das Casas’’), one Tunisian (‘‘Sidi Daoud’’)
and one Spanish (‘‘Barbate’’) time-series. For time-series longer than 20 years, the trend is estimated by EVF (see the text), in
other cases by a running median.
is simply descriptive and not inferential. An EVF was Results
performed on this time-series to depict the long- and
medium-term fluctuations. According to the classification on the distance matrix
(in km), the 54 traps were classified into five areas
All numerical analyses were performed using Matlab corresponding to: Portugal, Spain and Morocco,
(1999) and S-plus (1999) software.
