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In this respect the Port Health Authority by exercise of its functions relative to rodent
control in ocean going vessels, coastwise shipping, river lighters, and shore premises within
the curtilage of the Port of London Authority, has made a contribution of primary importance,
resulting in a greatly diminished possibility of re-infestation from these sources, which has
become evident in the City and equally the riverside of the riparian Boroughs.
The importance of this contribution is accentuated by the figures of shipping entering the
Port during the year under review. They comprise 16,135 vessels from foreign ports and 11,139
coastwise vessels with a combined gross tonnage of 43,424,411 tons. In addition these vessels
were served by 7,000 lighters receiving cargo overside for distribution to wharves and warehouses
on both sides of the river.
The importance of hygiene, relative to rodent control, embracing proper garbage disposal,
food storage and elimination of structural and incidental harbourage must be emphasised. Maintenance
of good general conditions, whatever the usage of property, is essential forthe permanent
control of commensal rats and mice, and the application of control measures should be regarded
as supplementary to hygiene.
In the field of catering premises, both public and private, the continued improvement embracing
the abovementioned provisions has been maintained, thereby contributing to the overall position
of Ship rat infestation.
Regarding the old types of properties used mainly as offices, many of these have been
entirely reconstructed internally, resulting in the removal of structural harbourage, while others
have been effectively improved. In addition occupiers have become rat conscious and do not
hesitate to seek advice and assistance.
To summarise the position of Ship rat infestation it will be of interest to include the conclusions
of an interim summary based on a survey of the Ship rat in the United Kingdom made by
Officers of the Ministry of Agriculture, Fisheries and Food, two years ago in co-operation w ith
Local Authorities.
The date has now been collated and the full report will be published shortly. Meanwhile,
the interim summary covering the period 1951 - 1956 provides the following:—
(1) In 1951 the Ship rat was reasonably well established ashore in the London area and in
about 40 localities outside it, and occurred sporadically in about 30 other places.
(2) By 1956 it had decreased in range and frequency in most localities and disappeared
from some.
(3) The main factors responsible for its loss of ground between 1951 and 1956 are thought to
be the continuous reduction in the number of rats arriving in the ports in ocean-going
vessels, the introduction of measures to reduce rat infestation on coastal vessels,
improvements in dockside building construction and improved methods of control on land.
(4) It is thought that the ship rat will lose more ground in the next few years, but can be
expected to persist fora considerable time yet, at least in London, Bristol and Liverpool,
and perhaps in Leith and Belfast.
The 31 Common rat infestations which were the subject to control measures were mainly confined
to re-building sites in varying stages of construction. These sites offer facilities, and are
in every way conducive to this type of infestation, but taking into consideration the vast reconstructure
carried out in recent years, the size of the sites, and wide distribution, the problem
has not in any way reached the degree visualized at the onset of rebuilding.
From the moment the contractors occupy a site the inducement to infestation is provided.
Huts are erected, slightly raised from the ground thereby offering harbourage; old and often
obsolete drainage is broken into as the site progresses; structural harbourage, although temporary,
is available, and to this must be added the incidental nesting facilities provided by the
vast quantities of materials and accumulations common to such sites. The temporary canteens
provided for the workmen are in the main well maintained, but nevertheless are an attraction to
rats and mice. The principal food supply is, however, provided by the numerous workmen
employed on the sites who, preferring to eat their meals other than in the dining room provided,
distribute food over the entire site by haphazard disposal of remains, and without regard to the
fact that they are encouraging infestation.
All building sites were inspected periodically, and when such conditions were found to exist
the necessary action was taken by the contractors as far as practicable, having regard to the
conditions and labour involved.
The gradual increase and wider distribution of mice infestation apparent in recent years,
and coinciding with the decrease in rats, has not been quite so noticeable, there being a reduction
of 30% in major infestations treated, while the number of infestations in the minor category
remained fairly constant.
In reviewing this problem there appears to be a connection with the comparable decrease in
rat infestation, there being little doubt that the absence of rats has left the way clear for mice,
which do not respond to control measures in the like manner of rats
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