THE BREEDINQ O F THE NORTH ATLANTIC FRESIIWATER-EF1.S
143
We do not know exact temperatures in relation to the behaviour
of A . rostrutu, but Bigelow and Schroeder say (1953, p. 152): " Eels
tolerate a wide range of temperature. But it is common knowledge that
those inhabiting the salt marshes and estuaries of our Gulf, and its
tributary streams, mostly lie inactive in the mud during the winter.)'
On the basis of this statement I feel myself justified in concluding that
the reaction of A . rostratu towards temperature is much the same as
that of the two other northern temperate eels, the Japanese and the
European.
First I may mention then that temperature conditions in the Katte(Danish waters) as shown by Tucker ( 1959aJ p. 496, Fig. 2) have no
relation whatsoever with the migration of the European silver eels,
because they do not migrate at all at the temperatures shown, 0" to
5" c.
But, most important, Tucker, maintaining that there can only be one
inherited pnttcrn of behuviour, uscs this postulih in his arguments
&ut tho 1Ciiropwii id, lmt for@ nll nlmit it ~ I i m hc ApenkR ahout
t l i v Aniericrin wi.
His scntencc. thnt tlic: fiitc of the hiissiwi1pi wls riced not concern us
rnakes onc ask why 1'11cIwr uses so m w h space in arguing about the
Mcditerranean stork wlicn considcring t he 12uropcan eel; even if the
observations O N p. 4!)7 slioiild be of minor jml)ortance in the light of new
and well-established facts in favour of Ekman's (1932) and Tucker's
hypothesis, it might just as well be stated that the fate of the Mediterranean eels need not concern us.
But as regards the simple, rapid and direct path of the East American
eel, leading to the breeding places, I fail to wc its simplicity, keeping in
mind that the breeding must take placc ahol I: the occanic tlicrmoclinc,
probably not deeper than 500 m, at tempcr"ttures of about 15°C. The
deep countercurrent of the Gulf Stream off South Carolina is a true
abyssal current. Instead of referring to Swallow (1 957), as Tucker does,
I may be allowed to cite Swallow and M'orthingtc~n ( 1 959), which waR
published well before Tucker" last article ( 1 !,tIO).
SwJlow rmrl
Worthington write (1956, p. 444): " Southwly volocition of tJ€3tW(!f:tl
2 and 9 cm/sec were mcasiired at it dc:pth of :!58O 111 arid twtwcmn I) r~n(1
18 cm/Hec at 2840 m.
" The Icvc!l of no motion ww dctc*rrriiiicd from tho floatn o i i fivo
occasions. It fcll between 1649 arid 21MJ m mtl txtwocn tho pohntial
temperature surfaces 3.43" and 3-68'. "
So Tucker, assuming that the American eel, like the European,
shows positive reactions to high tempenLture and salinity, disregards
the fact that the American eel, in order to tuke advantage of the deep
143
We do not know exact temperatures in relation to the behaviour
of A . rostrutu, but Bigelow and Schroeder say (1953, p. 152): " Eels
tolerate a wide range of temperature. But it is common knowledge that
those inhabiting the salt marshes and estuaries of our Gulf, and its
tributary streams, mostly lie inactive in the mud during the winter.)'
On the basis of this statement I feel myself justified in concluding that
the reaction of A . rostratu towards temperature is much the same as
that of the two other northern temperate eels, the Japanese and the
European.
First I may mention then that temperature conditions in the Katte(Danish waters) as shown by Tucker ( 1959aJ p. 496, Fig. 2) have no
relation whatsoever with the migration of the European silver eels,
because they do not migrate at all at the temperatures shown, 0" to
5" c.
But, most important, Tucker, maintaining that there can only be one
inherited pnttcrn of behuviour, uscs this postulih in his arguments
&ut tho 1Ciiropwii id, lmt for@ nll nlmit it ~ I i m hc ApenkR ahout
t l i v Aniericrin wi.
His scntencc. thnt tlic: fiitc of the hiissiwi1pi wls riced not concern us
rnakes onc ask why 1'11cIwr uses so m w h space in arguing about the
Mcditerranean stork wlicn considcring t he 12uropcan eel; even if the
observations O N p. 4!)7 slioiild be of minor jml)ortance in the light of new
and well-established facts in favour of Ekman's (1932) and Tucker's
hypothesis, it might just as well be stated that the fate of the Mediterranean eels need not concern us.
But as regards the simple, rapid and direct path of the East American
eel, leading to the breeding places, I fail to wc its simplicity, keeping in
mind that the breeding must take placc ahol I: the occanic tlicrmoclinc,
probably not deeper than 500 m, at tempcr"ttures of about 15°C. The
deep countercurrent of the Gulf Stream off South Carolina is a true
abyssal current. Instead of referring to Swallow (1 957), as Tucker does,
I may be allowed to cite Swallow and M'orthingtc~n ( 1 959), which waR
published well before Tucker" last article ( 1 !,tIO).
SwJlow rmrl
Worthington write (1956, p. 444): " Southwly volocition of tJ€3tW(!f:tl
2 and 9 cm/sec were mcasiired at it dc:pth of :!58O 111 arid twtwcmn I) r~n(1
18 cm/Hec at 2840 m.
" The Icvc!l of no motion ww dctc*rrriiiicd from tho floatn o i i fivo
occasions. It fcll between 1649 arid 21MJ m mtl txtwocn tho pohntial
temperature surfaces 3.43" and 3-68'. "
So Tucker, assuming that the American eel, like the European,
shows positive reactions to high tempenLture and salinity, disregards
the fact that the American eel, in order to tuke advantage of the deep