These data represent some mean values from a series from Tripolitania, 

 which do not differ noticeably from others from other regions of the 

 Mediterranean, The values for the first two years are drawn from examina- 

 tions of Adriatic tuna because the tuna fisheries of Tripolitania, like 

 those of Sicily and Sardinia, do not capture, normally, tuna one and two 

 years old (immature). 



8 ) The migrations of no n- spawning tuna are no t_ influenced by 

 salinity at least within veiy wide limits. — The hooks indicate that the 

 same tuna may frequent indifferently waters of a high saline character, 

 like those of Ionia and Cyrenaica (38 - 38.5 O/OO), as well as moderately 

 saline waters, like those of the Atlantic (Azores, North Spain 35»5- 36.5 

 O/OO), or those weakly saline like the Oslofjord (32 - 34 O/OO^ But 

 even more extraordinary is the presence of tuna in waters of a very low 

 salinity, as are those at the surface of the Sea of Marmara and the 

 Bosphorusj a presence not accidental, but normal, and which even supplies 

 an important fishery (about 100,000 kg a year). Tuna are caught at 

 Constantinople with hooks at shallow depths and also with harpoons when 

 they come to the surface (at Arnaud Cheni and other points in the 

 Bosphorus); this means that they occur in the current issuing from the 

 Black Sea, which flows like a weakly saline river over a deeper stratum 

 which has a salinity differing only by several units from that of the 

 Mediterranean. In the Bosphorus there are salinity values of around 

 18.00 O/OO, and to find values greater than 30oOO O/OO it is necessary 

 to go below 40 m. (see Sta, 171, Thor , 1910, at the very point where 

 tuna are taken with the harpoon)., It is therefore certain that the tuna 

 frequents even this upper strrtum and does not keep only to the strata 

 underneath (it further appears that tuna are numerous even in the central 

 Black Sea). Before the absolute identity of the tuna of Constantinople 



U From the point of the snout to the middle point of the caudal fin, 

 excluding the two lobes of the fin. 



2/ In the Gulf of Trieste (August 1927) our analyses, made on samples 

 collected at the same time and the same place in which the tuna were 

 seen, gave salinities varying between 32.74 O/OO and 37o00 O/OOe 



