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34
reefs afford no help. In order to meet the London facts it. is necessary to picture,
as aforesaid, neighbouring foothills, suggesting the possible existence of more
distant mountain masses; the former presumably being continuous with the
latter and their material existence helping to confirm the suspicion that the far off
shapes are something more than the baseless fabric of a vision. Similar causes of
typhoid prevalence, then, according to London experience, have operated throughout
; but their power to cause mischief has steadily lessened as the importance
of protecting certain food supplies has been increasingly appreciated. This line of
argument, so far as both cholera and typhoid fever are concerned, has been pursued
elsewhere ("Public Health" 1922 and 1923), and detailed reasons have been given
for concluding that some of the historical water outbreaks of cholera and typhoid
fever were really in all probability due to fish or shellfish; and that many of the
supposed milk and most of the ice-cream outbreaks were similarly attributable.
In the annual report for 1922 a diagram exhibiting the incidence, in "four
weekly" periods, of typhoid fever in London during thirty-two years (1891-1922)
appears on pp. 20 and 21. This diagram shows a very heavy incidence of the disease
upon the London boroughs—particularly upon the poorer boroughs—during the
earlier two thirds of this series of years; the more extensive prevalences occurred
in the years round about the close of the last century; and then, particularly from
1905 or 1906 onwards, there was notable decline, which became quite considerable
in 1909, developed still further after 1911, and resulted almost in extinction with the
outbreak of the war. This almost complete immunity from prevalences in poor
areas, of the kind experienced up to 10 or 15 years ago, was substantially maintained
until last year, when an outbreak of typhoid fever, affecting the type of area which
suffered in former years, occurred in Bethnal Green.
The association of the outbreaks of earlier years with small plaice has been
considered from time to time in these reports (see Annual Report for 1922,
pp. 24-29). Reference has also been made to the efforts of the fish trade, from some
20 to 10 years ago, to obtain legislation preventing the sale of fish under a certain
size. The object of such legislation was primarily to prevent injury to the plaice
fishery in the North Sea.
The recently published Report on Sea Fisheries 1919-23 of the Ministry of
Agriculture and Fisheries (pp. 61-73) gives the results of the scientific work carried
out by the Department prior to, during, and more particularly after, the war. The
statistics obtained by the Department between 1903 and 1913 " prove at least that
the productive powers were not able to keep pace with the increase of fishing power,
though they do not necessarily show a period of over-depletion to have been inaugurated.
Lastly, the flatfish with their relatively restricted wanderings and accumulations
of young stages on the Continental shallows, easily accessible to the trawl,
are of all demersal fish the most vulnerable. It is precisely this intensely fished and
important region in which fishing was most effectively restricted by the war, and
precisely the shelving eastern portions of its bed that lay to the greatest extent under
the effective protection of mines. The heavy landings made by trawlers during the
later years of the war and the large size of many of the fish taken was a universal
matter of comment in the trade and was commonly ascribed to the effect of restriction
of fishing. There can be no reasonable doubt that this opinion was in the main
correct."
This great experiment, unwittingly brought into operation by the advent of
war, focused attention upon the desirability of taking steps to protect the " small
plaice nursery grounds " after the termination of hostilities. The enquiries made to
this end resulted in the recommendations (July, 1921) of the Plaice Fisheries Sub
Committee of the International Council on Fisheries in the North Sea. These recommendations
contemplated prohibition of fishing by steam trawlers and motor vessels
of more than 50 h.p., in certain areas along the eastern and southern shores of the
North Sea, and limitation of use of other parts of these nursery grounds to April
May and June. The recommendations were approved in September, 1922, by the