138
ANTON F. BRUUN
forward “A New Solution to the Atlantic Eel Problem”. I n this article
Tucker (p. 496) rejects Schmidt’s assumption that the European freshwater eel (Anguilla anguilla L.) returns to the Sargasso Sea and ‘( proposes a new and drastically different interpretation of the observed
phenomena, namely: (1) That the European eels need not and do not
succeed in returning to the ancestral spawning-area, but perish in their
own continental waters. (2) That the American and European eels are
not distinct species, but merely eco-phenotypes of Anguillu anguilla, their
apparent distinguishing characters being environmentally determined
(in the manner of numerous precedents) by demonstrable differences
in temperature conditions encountered during the ascent from different
parts of the American eels’ spawning area to the surface, and their
distribution by demonstrable coincident differences in the subsequent
transport of the surface water-masses. (3) That the populations of
the so-called ‘ European ’ eels, A . unguilla, are therefore entirely maintained by reinforcements of larvae of American ‘A. rostratu ’ parentage.’’
Tucker’s hypothesis thus leaves us with the implication ‘( that
Europe and North Africa are regularly colonized by eels of American
ancestry doomed to perish in a fruitless suicide-migration.”
No wonder this statement has had a great appeal to the general
public and has been very widely spread by magazines and newspapers.
With Dr. D. W. Tucker’s background, the British Museum (Natural
History), it is quite natural if teachers of biology have come to doubt
whether Schmidt was right in his solution of the problem about the
breeding places of A . anguilla. They may think this is still a problem
in which two hypotheses are possible; for Tucker claims at least parity
with Schmidt. But I propose to provide sufficient evidence to prove
that this is far from being the case.
Three scientists have already put forward @XJd argurricritH iqpinwt
Tucker‘s ideas (D‘Ancona, 1959; Jones, 195!); l ~ c c l ~ l ~ ~ r ,
IOAO). I n r:ac:ti
case Tucker (195Yb, lSWc, 1960) has fully mttintairicd nrirl c:xtc:iltIt4
his own ideas. 1 shall restrict mync?lf to dincuHnirig what ‘l‘iwkw hirnnc*ll‘
has put forward. I h v c fourid it impowitilc to i11(:11itIc rwicwe in
g(wml (:VCII i f t h y havc h r i i i i favour of ‘I‘uckor’n i(I(:a~ (Jde ‘J’ucker,
I!G!k, 1’. 1283).
Tucker has founded his hypothcsis on part of thc cxisting literaturo
without any new observations of any kind; so although I have hecn
working with Schmidt and Schmidt’s collections since 1924 I shall not
use anything unpublished from this material; but will only mention
that any new observations which may have been made or old observations studied in more detail than already published by Schmidt, have
only given further support to Schmidt’s conclusions.
ANTON F. BRUUN
forward “A New Solution to the Atlantic Eel Problem”. I n this article
Tucker (p. 496) rejects Schmidt’s assumption that the European freshwater eel (Anguilla anguilla L.) returns to the Sargasso Sea and ‘( proposes a new and drastically different interpretation of the observed
phenomena, namely: (1) That the European eels need not and do not
succeed in returning to the ancestral spawning-area, but perish in their
own continental waters. (2) That the American and European eels are
not distinct species, but merely eco-phenotypes of Anguillu anguilla, their
apparent distinguishing characters being environmentally determined
(in the manner of numerous precedents) by demonstrable differences
in temperature conditions encountered during the ascent from different
parts of the American eels’ spawning area to the surface, and their
distribution by demonstrable coincident differences in the subsequent
transport of the surface water-masses. (3) That the populations of
the so-called ‘ European ’ eels, A . unguilla, are therefore entirely maintained by reinforcements of larvae of American ‘A. rostratu ’ parentage.’’
Tucker’s hypothesis thus leaves us with the implication ‘( that
Europe and North Africa are regularly colonized by eels of American
ancestry doomed to perish in a fruitless suicide-migration.”
No wonder this statement has had a great appeal to the general
public and has been very widely spread by magazines and newspapers.
With Dr. D. W. Tucker’s background, the British Museum (Natural
History), it is quite natural if teachers of biology have come to doubt
whether Schmidt was right in his solution of the problem about the
breeding places of A . anguilla. They may think this is still a problem
in which two hypotheses are possible; for Tucker claims at least parity
with Schmidt. But I propose to provide sufficient evidence to prove
that this is far from being the case.
Three scientists have already put forward @XJd argurricritH iqpinwt
Tucker‘s ideas (D‘Ancona, 1959; Jones, 195!); l ~ c c l ~ l ~ ~ r ,
IOAO). I n r:ac:ti
case Tucker (195Yb, lSWc, 1960) has fully mttintairicd nrirl c:xtc:iltIt4
his own ideas. 1 shall restrict mync?lf to dincuHnirig what ‘l‘iwkw hirnnc*ll‘
has put forward. I h v c fourid it impowitilc to i11(:11itIc rwicwe in
g(wml (:VCII i f t h y havc h r i i i i favour of ‘I‘uckor’n i(I(:a~ (Jde ‘J’ucker,
I!G!k, 1’. 1283).
Tucker has founded his hypothcsis on part of thc cxisting literaturo
without any new observations of any kind; so although I have hecn
working with Schmidt and Schmidt’s collections since 1924 I shall not
use anything unpublished from this material; but will only mention
that any new observations which may have been made or old observations studied in more detail than already published by Schmidt, have
only given further support to Schmidt’s conclusions.