48
THE BIOLOGY OF FISHES
pract1cally the same time (summer),
are
among
the
phenomena which led Pavesi to believe that the Tunny
mostof the year in the deep water off the coasts.
{As thè“=Ëäpawning time approaches, the sh rstof all make a ;
vertical"; migration,
_
from the .depths to the surface. It is
-
sa1dthat neWîàrrivals in the surface waters can be distin—
._
_g”ùi‘êhed from the earlier by their dark“ër colour. Then they
l‘rriôve toWards the shallower waters to spawn.
It is the
_,
’
latter, the horizontal moVement, which has given rise to the
idea of immigration from the Atlantic and Which accounts
”for the elaborate preparations made by the shermen for
_
thereception of the Tunny. . —
_
,
—
It is not only the Mediterranean, hoWever, that the
‘
Tunny frequents. The greatest shery indeed lies outside, ' ’
in the Bay “of Cadiz, and here as in the Mediterranean the
‘
_
concentration of the sh on the coast is due to the sp‘awning
migration… It is also—taken on the western side of the
Atlantic.
On the other hand, ithas been found much further
'
‘
nofth,in British waters, NorthSea, Scandinavian coasts,and
1
the skullshaVe:eVenbeen taken—in IcelaridiÇ'”Waters ; within
number have been-_ captured in the
These are
they are the largerçsh which,
Ï
the
on the: Spanish_EOr Portuguese ,
—
coàsts, follow the- Sar—dine iàd‘»MâCk6fi' shQal‘s:horthwards,
ï
'
and latergfeed _ on the autumn : HerrmgoftheNorth
_
; When
161a‘d ofHerrmg1shauledupthe
TunnÿfWdnptthptdnghdndtl
=
'
°
Possiblÿltwaswstascommen1nearherÿéars there is a
'
record by Schonevelclethat 1twas ë—faiy Common near
-
back as the
”
bÇgihning‘in Connection
Thé .Porpoige 'may often
'
-
; havebeen
but until the traWl
.
wasusedf0ï the capture ofl Herrings- in large quantities,
‘
rarity;
_
As—With ”the Tunny-,—
members of
'
S_corbroidg
They are