30 

 20 - 



<0 



30 

 20 

 10 



««j 30 



S 20 



30 

 20 

 10 



30, 

 20 

 10 



30 

 20 



10 



1958 



1965 



-£7- 



1966 



'-f.?- 



1967 



1968 



1968 



1969 



1969 



■£2- 



1970 



1970 



1971 



i-^^ 



100 



200 

 LENGTH (cm) 



300 



150 200 



L ENG7H (cm ) 



Figure 57. Lengths of bluefin tuna t;iken in the Sicilian trap catches in 1958 ;md 1965-1971 ("+" on graph means less than 

 0.5%). 



weight groups and months, of the 

 catches for most of 1948-1950 and 

 1953-1954, with the sex ratios for 

 some samples. The bluefin taken in 

 the winter fishery were mostly in the 

 medium size group, but with many 

 small t'lsh and a few giants. The in- 

 troduction of live-bait chumming in 

 1950 increased the catch from a few 

 hundred fish per year to as many as 

 1,500 in a montlr, but after 1953 the 

 catch declined. The summer catches 

 were nearly all giant fish, with a few 

 mediums. Only from 23 to 44 fish 

 per year were taken in 1948-1950, 

 and none were caught in 1953-1954. 



The sex ratios of the tuna taken 

 in these years showed a veiT slight 

 predominance of females (about 52% 

 females), which did not van,' greatly 

 between months and years. Arena 

 (1959a) described a productive line 

 fisher)' off tiie Aeolian Islands (north 

 of eastern Sicily). Up to 27 fish were 

 taken per boat day under favorable 

 conditions. It was necessary' to use 

 fine lines baited with sand launces, 

 Ammodytes cicirella. The fish taken 

 generally ranged from 30 to 40 kg. 

 Much larger individuals, 200 kg and 

 over, were often hooked, but usually 

 broke the light lines. The Italian 



longliners fished primarily for 

 broadbill swordfish, but caught blue- 

 fin tima incidentally (Sara and Arena 

 1967). Their tuna catches have not 

 been recorded in (he statistics. R. Sara 

 (personal conimunicalion) estimated 

 that the swordfish longliners might 

 have captured "not over 500" tima 

 with an average weight of about 1 50 

 kg during the 1972 season. Sara and 

 Arena (1967) noted that smaller 

 longlines used primarily for dolphin 

 (fish), Coiyphaena hippurus 

 Linnaeus (1758), also took 

 unrecorded numbers of small blue- 

 fin. 



60 



