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and those of Cyrenaica, Tunisia, and Sardinia was established, these
differences of salinity could be attributed to different adaptations,
in relation to differences of race, but once the possibility is
recognized that the same tuna, as an individual, may move indifferently
between these various points, it is necessary to come to the conclusion
that its movements are not noticeably influenced by salinity, within
the very broad limits specified above,,

It does not seem to me, therefore, that the theory of Roule can
be maintained, according to which the tuna, even though non-spawning,
although with less strictness than when ripe for spawning, tends to seek
and remain in the most saline waterso

Even the strict stenohalinity and stenothermy of the ripe tuna,
furthermore, in the sense maintained by Roule of a concentration of tuna
on spawning grounds with maximum salinity and temperature (even if con-
sidered as limited to certain basins, for generalizing one falls into
an absurdity), has not found confirmation in numerous salinity determina-
tions (over SOO) made by us in the past 2 years from samples which we
had collected on 12 tuna fishing grounds in Sardinia, Calabria, Sicilia,
P\iglia, and Tripolitania, nor in observations of temperatures.

Therefore it can be concluded at the present time, and thus only
provisionally (because to arrive at definitive conclusions it is
necessary to be able to compare the conditions of several years), that
the small and medium mature tuna (Calabria, Tripolitania) and the large
ones (Favignana and the groun of tuna fisheries of Carloforte) have
somewhat different habits5/and that the larger tuna would prefer waters
relatively less saline and less warmo High salinities do not appear to
be favorable to ripe tuna, and this would be one of the causes of the
lack of tuna spawning grounds in the eastern Mediterranean^ One should
speak of seeking, not the most saline and the warmest waters, but waters
having definite characteristics.,

9) Is the balance between the tuna of the Atlantic and the
Mediterranean influenced by the transportation of eggs and 'larvae
through the Strait of Gibraltar?
Roulei2/ supposes that if a passage of tuna through the Strait
does occur, it must happen through the passive transport of larvae from
the Mediterranean to the Atlantic in the deep outflowing current, these
seas still remaining practically independent with regard to the adult

w Even -fclie season can be somewhat different, thus in Tunisia ajid
Tripolitania the tuna fisheries made their catch latere
Cons, Int. Bxplo de la Mer, Rapp„ et Po V, , vol, 34| Office Sc, et
Techn, PStehes Mar, , Notes et Memo , Noo 39o