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The two important commitments, one in obedience to the specific part of the International
Sanitary Regulations, 1951 emphasises the health aspect, while the other is concerned with the
provisions of the Prevention of Damage by Pests Act, 1949 and the subsequent Prevention of
Damage by Pests (Application to Shipping) Orders, 1951-1956; both of which direct the attention
to economic losses ashore and afloat.
Although differing in specific intention, it is significant that these pieces of legislation are
complementary to each other and combine to provide a complete defensive system satisfactory to
both requirements, otherwise the more dramatic role of preventing the entry, spread and communication
of plague would be seriously undermined if rodent infestations were allowed to
develop freely within the port and become a potential reservoir of disease. In this connection,
the Rodent Control Scheme for shore premises has contributed very effectively.
There remains another potential reservoir of disease with widespread communications within
the Port and includes nearly eight thousand lighters or barges. Any plague infection communicated
by one or more of these could become remotely established at terminals before being
detected. Control of these craft has been intensified during this year, and the recorded results
must surely remove any serious anxiety arising from this aspect.
In addition to the exterminating measures adopted, specimen rats are systematically recovered
from shore premises and vessels, particularly those associated with rodent-attractive cargoes
from plague 'suspected' ports, and these are submitted for bacteriological examination. Incidentally,
this routine serves as a check on prevailing conditions among the native rodent
population.
The wide range of trading interests and associated transport systems involved make a major
seaport vulnerable to continuous rodent infestation, from which it can be defended only by
constant vigilance and determination by the rodent control staff.
It is generally accepted that three conditions must be satisfied to promote rodent infestations,
e.g.
(a) Adequate supply of food and drink.
(b) Adequate harbourage in which to shelter and breed.
(c) Adequate means of communication.
To a great extent it is not possible to deny them food and drink, but harbourage and communications
can be drastically eliminated. A major feature in this Port is to discourage both in
all new construction and make amends wherever practicable in existing premises and vessels.
In this determined effort, the Industry as a whole has generously assisted to mutual advantage.
A variety of extermination measures are in practice and include fumigation, direct poisoning
by ingested food and drink, trapping and poisoned tracking dusts. The availability of attractive
cargo as food can be an impediment to a successful poisoned food technique if the rodents so
choose, but rats normally succumb to the temptation of drinking any water reasonably palatable —
even poisoned water — and this tendency enhances the value of '1080'.
Rodents, particularly mice sometimes pose difficult problems. One may become dismayed by
a belief that the extermination of the rats encourages an infestation of mice and added difficulties.
"Necessity is the spur to invention" — a truth which manifests itself in conscientious
rodent control.
Alternative measures are constantly investigated by the staff, such as the poisoning of
nesting materials and the habitual runs, or by providing suitably poisoned materials (dieldrin)
over the habitual runs, thereby acting as a direct contact poisoning to be absorbed by the feet of
the rodents.
It is quite reasonable to conclude that those engaged on this work are giving very satisfactory
service and leave very little opportunity for any justifiable complaint.
RODENT CONTROL ON LIGHTERS
Mr. W.G. Stimson, the Senior Rodent Inspector, has provided the following figures relating
to rodent control work carried out on lighters:-
Number of lighters inspected 7,207
Number without evidence of rodents 6,220
Number with negligible evidence of rodents 894
Number of lighters treated for rodents 93
Total number of dead rodents recovered from lighters after treatment 552
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