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NOVEMBER 29, 1906| 
NATURE 
107 
investigations extending uver large areas are so great that 
it would be a decidedly retrograde policy that such cooper- 
ation should be abandoned. In support of the opinions >x- 
pressed above, the council adduce the following statements 
and arguments with reference to sections (1) and (2) re- 
spectively, and believe that the statements will be fully 
substantiated in the detailed reports on the international 
investigations already published or in course of preparation. 
(1) In conformity with the main object of British par- 
ticipation in the international scheme of investigations, 
as explained in the House of Commons by Mr. Gerald 
Balfour on June 12, 1902, and in accordance with resolu- 
tions of the International Council at Copenhagen in July 
of the same year, the investigations carried out in the 
North Sea by the association, at the request of H.M. 
Government, have been largely concentrated upon the 
biological aspects of the undersized-fish question, especially 
as concerns the supply of plaice. 
By means of nearly 1000 hauls of the trawl the sizes of 
the plaice in different parts of the southern North Sea 
have been determined in detail and mapped out for different 
seasons of the year. The measurements of plaice recorded 
at sea on the S.S. Huxley exceed a total of 100,000. 
These investigations have clearly revealed the distribution 
of the various sizes of plaice in the English area during 
the period of investigation, and have contributed extensive 
material towards the collective report on this subject which 
is in preparation by the International Committee. 
The causes which influence this distribution have been 
carefully investigated with respect to (1) depth; (2) nature 
of sea-bottom ; (3) character of the food-supply ; (4) growth, 
age, sex, and maturity; (5) locality of the nursery and 
spawning grounds; (6) seasonal migrations; (7) density of 
fish-population ; and (8) intensity of fishing; and on most 
of these points definite results have been obtained. 
By means of experiments with more than 7ooo marked 
plaice the migrations of this species have been plainly 
traced in important areas, and much progress has been 
made towards the explanation of the observed movements. 
The same experiments have furnished important results 
concerning the rate of growth in the chief parts of the 
English area. 
An examination of the otoliths of more than 12,000 plaice 
caught and measured during the trawling investigations 
has yielded much new information concerning the age of 
plaice at different sizes on the chief fishing grounds, and 
has indicated a valuable method of controlling the results 
obtained from the marking experiments. 
The marking experiments have afforded a new factor for 
estimating the intensity of fishing under modern conditions, 
and for measuring differences in this respect in different 
regions. In the case of medium-sized plaice (10-15 inches 
in length), we have found that out of 1100 fish of this 
size liberated at various seasons of the year in the southern 
area, where sailing trawlers predominate, approximately 
30 per cent. have been recaptured within one year from the 
date of liberation, and that out of 400 fish similarly set 
free on the Dogger Bank and adjacent grounds, where 
steam trawlers predominate, about 40 per cent. have been 
recaptured in the same period. 
The council regard these results as of great significance 
from a practical, as well as a scientific, standpoint, 
especially as there is reason to believe that the figures 
understate the full severity of the fishing. 
Other results derived from the marking experiments and 
otolith investigations throw new light on the relative 
mortality of the two sexes, their habits of seasonal segre- 
gation, and their relative susceptibility to capture by the 
‘trawl, points which bear directly upon the problem of the 
effects of trawling upon the economy, and therefore the 
supply, of this species. 
By the transplantation of large numbers of small marked 
plaice from the coastal waters to the Dogger Bank and 
other grounds, it has been found, during two years in 
succession, that the rate of growth is much greater on 
the Dogger Bank than on the nursery grounds, and the 
consideration of other factors renders it highly probable 
. that the supply of fish can be profitably influenced by the 
transplantation of small plaice on a commercial scale. 
A number of special experiments have been carried out 
on the Huxley to determine the vitality of trawl-caught 
NO. 1935. VOL. 75] 
| plaice of different sizes. Owing to the variety of the 
conditions which influence the experiments, it is not 
possible at present to express these results in a single set 
of figures representative of average conditions, but the 
experiments support the opinions (1) that under commercial 
conditions of trawling on the nursery grounds a large pro- 
portion of the small plaice taken are mortally injured, and 
would not live if returned to the sea, and (2) that the beam 
trawl is less injurious than the otter trawl under similar 
conditions. 
With respect to other food-fishes, such as cod, haddock, 
sole, turbot, &c., a complete register has been kept of the 
catch of the large commercial trawls on every occasion 
(between 900 and 1000 hauls), and about 250,000 measure- 
ments, exclusive of those of plaice, have been recorded. 
The information thus acquired has laid a broad basis of 
exact and trustworthy knowledge concerning the general 
features of the fish-populations of different fishing grounds, 
and concerning the size, weight, and to some extent the 
rate of growth of the various species represented. 
This information has been supplemented by more than 
700 experiments with fine-meshed nets and dredges for 
determining the character of the sea-bottom itself, the 
dominant features of the bottom fauna, and the distribu- 
tion of the fish eggs and fry which escape the commercial 
nets. In particular cases experiments have been carried 
out on the migrations and rate of growth of marked fishes, 
especially of cod, sole, lemon sole, and latchet, and the 
relation of size to age in the case of cod and sole has 
been studied to a certain extent by means of otoliths. 
Extensive observations have been made upon the food of 
many species in different localities, and concerning their 
relations to one another either as prey, competitors, or 
enemies. i : 
With regard to the hydrographic and plankton investi- 
gations specified in the international programme, the 
association has fully carried out its obligations in this 
respect by the most thorough and painstaking investi- 
gation of the waters of the English Channel. The results 
have been regularly forwarded for incorporation in the 
quarterly charts and records issued by the Bureau of the 
International Council, and have been reported on from 
year to year. ; 
(2) In view of the fact that special research has been 
mainly concentrated hitherto upon the plaice, and that 
other valuable species present points of practical import- 
ance which still await solution, especially the sole, turbot, 
cod, and haddock, it is very desirable that the investi- 
gations which have been begun on these species should be 
continued and developed. 
| In this connection the council would point out that the 
necessity of scientific investigations has been generally 
recognised, whether such investigations be or be not carried 
out under a scheme of international cooperation. : 
While the council have indicated above the substantial 
progress which has been made with the experimental work 
at sea under their control during the past few years, they 
strongly urge that if this work should be brought to a 
| sudden conclusion the prospective value of much_ pre- 
liminary labour and expense would be lost. Continuity of 
work is a factor of more than usual importance In experi- 
mental investigation of this character, not only because 
the conditions of the phenomena are constantly changing, 
but also because the extent and value of the results likely 
to be obtained are largely dependent on the experience of 
the staff employed. 
NOTES. 
M. Mascart is retiring from the position of director of 
the Central Bureau of Meteorology in Paris. He will be 
succeeded on January 1, 1907, by M. Angot. 
Mr. L. A. Perincury has been appointed to the director- 
ship of the South African Museum, Cape Town, to fill 
the vacancy caused by the resignation of Mr. W. L. 
Sclater. Mr. Peringuey, who has been assistant director 
for some years, is a well-known entomologist, and author 
of many papers on South African Coleoptera and. other 
insects. 
