1. science
2. weather

COLONIAL OFFICE
FISHERY PUBLICATIONS No. 18, 1961
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a a an
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raw In
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The Experimental and Exploratory Fishing Cruises
of the F.R.V. Manihine in Malayan and Borneo Waters, 1955-56
with a Note on Temperatures and Salinities in the Singapore Strait
By F. D. OMMANNEY Ph.D., A.R.C.Sc.
PERPUSTAKAAN
NEGARAMALAYSI
A
JB 1275
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LONDON
HER MAJESTY' S STATIONERY OFFICE
19 6 2
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( 817044
~- 7 SE P )995
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CONTENTS
Introduction
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Narrative
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Temperature and Salinity Observations
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The South China Sea
Temperatures, surface
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30 m.
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Vertical distribution of temperature and salinity
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60 m.
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Salinities, surface
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60 m.
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80-100
The Malacca Strait
Temperatures
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Salinity
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Fishing Trials .
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Trawling survey
South China Sea
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Gear used
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Method of working
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Character of the bottom of the South China Sea
Catches in the South China Sea
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The Fish Fauna
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PERPUSTAKAAN
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The Malacca Strait
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Character of the bottom in the Malacca Strait
Catches in the Malacca Strait
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Sharks and Rays
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Sharks Carcharinidre
Orectolobidre
Scyliorhinidre
SphYllIidre
Rays,- Rhinobatidre
Trygonidre
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Variations of the otter trawl catch with depth
Night trawling .
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Discussion
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Contents ( Continued)
Trials with Other Types of Fishing Gear
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2. Long- lines
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3· Drift nets
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4· Trolling lines •
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5· Lalilpara net
6. Blanket lift net •
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Acknowledgements
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References
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Tables
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S11lIlIOaJ
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A Note on Temperatures and Salinities in the Singapore Suait
Introduction
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The Singapore Strait
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Teillperatures
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Salinities
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Sll1lllnary
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Acknowledgements
References
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Tables
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PERPUSTAKAAN
NEGARAMALAYSI
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INTRODUCTION
THE MOTOR Fishery Research Vessel Manihine is a steel trawler of 208 gross tons and 117 ft.
in length, powered by two National RVMS type diesel engines of 220 horse-power.
She was built in 1906 as a single screw steam trawler: but in 1937 she was converted for use
as a yacht. Her single steam engine was removed, and the twin National diesels installed, while
her accommodation was completely remodelled.
The Manihine proved to have excellent sea-keeping qualities and to be economical to run.
During the II months of her stay in Malayan waters she covered a distance of 15,700 miles
without any trouble at all. On the fishing grounds it was found that the twin engines and twin
screws, while giving ease of manoeuvre, were in fact something of a disadvantage owing to the
danger of the screws fouling the nets.
The terms of reference called for the exploration and investigation of the offshore waters of
Malaya and Borneo. It had rightly been assumed that the native inshore "subsistence" fisheries,
with their numerous separate individualllOits and highly specialised gear, were (1952) saturated.
In the case of Malaya and Singapore, at any rate, these fisheries, scattered along an extended
coastline and often far from market centres, were producing as much fish as they were capable of
producing, but the total yield was not enough for the very rapidly growing population. It was
believed that the fishing industries of these territories must now move outwards into hitherto
unexplored extra-territorial waters.
In this context, the term "extra-territorial waters" may be taken to mean waters beyond the
three mile limit and beyond the 10 fathom line.
The area of extra-territorial water to be explored was enormous. The Malay Peninsula,
Singapore Island and the British territories of northern Borneo (Sarawak, Bmnei and British
North Borneo) have together a coastline more than 3,000 miles in length. The area of sea to be
investigated included on the west the Straits of Malacca, and the waters of the Indian Ocean to
the northward over the continental slope, and on the east the South China Sea as far east as the
north-eastern extremity of Borneo. This section of the South China Sea alone has an area equal
to half that of the Mediterranean. Singapore was chosen as the base from which the research
unit was to operate on account of its central position at the junction of these two great east and
west water masses.
The Malay peninsula and the northern Borneo coast are flanked by wide areas of continental
shelf lying at depths between 30 and 50 fathoms and composed of soft oozy mud heavily overgrown with sponges and other marine growths. Over the South China Sea the north-east monsoon wind blows for half the year (November to March) and for several months high winds and
very heavy swells are met with.
It was evident that if these waters were to be exploited commercially it could not possibly
be done by the native inshore fishermen with their lack of capital, of long distance sea-going craft
and sea-faring tradition. Powerful long-range vessels would be required using the highly mechanized methods employed in temperate seas (trawls and long-lines). Extensive capital backing
would be needed for this and could only come from Europe or Japan.
Similarly the exploration and research which should precede and accompany commercial
exploitation would call for a powerful, long-range vessel with a high cruising endurance and
enough power to trawl, if necessary, on a very heavy and difficult bottom. Such a vessel would be
required in the course of her duties to make frequent voyages of a fortnight'S to a month's duration.
It was envisaged that the vessel would certainly have to carry out trial trawling and longlining operations as the two principal methods of bottom or midwater fishing in the open ocean.
With regard to pelagic fishing it was not thought likely that the pelagic shoaling fishes, which
have a largely inshore distribution, would come very much within the scope of the vessel's work,
but it was thought that there might be a fishery for the large predatory pelagic fishes (spanish
PERPUSTAKAAN
NEGARAMALAYSI
A
I
mackerel, dorado, barracuda, bonito, tuna, etc.) in the region of the 10 fathom line, along the
indented coastline and around the innumerable shoals, atolls, banks and islands scattered
throughout the area. It was therefore planned to equip the vessel for multiple trolling.
Fishing, however, is only part of the work of an ocean-going research vessel. An integral part
of her research must consist of hydrological and plankton surveys covering the waters to be
explored in order to build up a picture of the oceanic environment of the fish population.
NARRATIVE
AFTER PRELIMINARY trawling and gear trials in Plymouth Sound the Manihine sailed from
Plymouth for Singapore on 23rd June, 1955, under the command of the late Captain D. R.
Davies, M.B.E. She arrived at Penang on 9th August and at Singapore on 12th August.
The programme which had been drawn up with the agreement of the Director of Fisheries,
Federation of Malaya and Singapore, for the first years of the ship's work called for exploratory
and experimental fishing cruises covering a wide area of the South China Sea and the Straits of
Malacca. In implementing this programme the Manihine made 12 cruises of different durations
in the South China Sea and the Straits of Malacca during her stay in Malayan waters between
12th September, 1955, and 22nd August, 1956. She spent 194 days at sea during this period and
covered 15,192 Iniles. She landed in Singapore or at ports in the Federation of Malaya or in
Borneo a total of 28 tons of fish and 7 tons of sharks and rays. The scientific officers in charge
during these cruises 7ere Dr. F. D. Ommanney, Mr. D. N. F. Hall, B.SC., and Mr. J. H. Wickstead, B.SC. Except during cruises I, 2 and 3 these officers took turns at sea. After cruise No.8
Dr. Ommanney went on long leave and Mr. Hall remained in charge of the investigations. This
meant that there was only one scientific officer on board for the duration of anyone cruise. This
was not enough staff for the work involved in a trawling survey and placed a considerable strain
upon the officers concerned.
The cruises carried out by the Manihine in Malayan and Borneo waters are listed below.
Dates
Cruise No.
From
I.
2.
3·
4·
5·
6.
Area
To
PERPUSTAKAAN
NEGARAMALAYSI
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19·9·55
27·9·55
8.10·55
11.11.55
21.11.55
5.1.5 6
15. 11.55
13·12·55
29.1.5 6
7·
8.
9·
10.
II.
12.
Scientific
Officer in
Charge
Dr.Ommanney
Mr. Hall
2.5.5 6
8.6.5 6
20.8.5 6
28.5.56
5.7.56
22.8·56
Po. Tioman Pahang River and Jason Bay
(East coast of Malaya)
South China Sea east of Singapore Strait
Penang, Alor Star, N. coast of Sumatra,
Pangkor, Malacca (West coast of Malaya)
Po. Tioman (East coast of Malaya)
Kuching, Sarawak coastal waters, Brunei
Great Natuna, J esselton, Kuching and
S. China Sea
Penang, S.W. Thai coast, Pangkor (West '
coast of Malaya)
Po. Tioman, Anambas Is., South China Sea
Great Natuna, Kuching, South Natuna,
South China Sea
South China Sea east of Natuna Islands
South China Sea north of Natuna Islands
Malacca Strait
Mr. Hall
Mr. Wickstead
Dr.O
ey
Dr. Ommanney
Mr. Wickstead
Mr. Hall
Dr.Ommanney
Mr. Wickstead
Mr. Hall
Mr. Wickstead
Mr. Wickstead
In. addition to. fishing operations during these cruises a number of plankton stations was
established along lines across the South China Sea from Tanjong Sirik on the coast of Sarawak
to the Natuna Islands, and across the Malacca Strait between Cape Rachado and Tanjong
2
00
R
Medang and, farther north, between Po. Langkawi and Diamond Point on the coast of Sumatra.
At these stations hauls were made with fine and coarse plankton nets and the intention was that
they should be occupied repeatedly at as regular intervals as possible.
Observations of temperature and salinity were made at the surface and at selected depths
down to the bottom, at a large number of positions over the area surveyed both in the South
China Sea and the Straits of Malacca.
The Manihine ceased her work in Malayan waters on 22nd August, 1956, owing to the sudden
illness while at sea of her Skipper, Captain D. R. Davies, M.B.E. The Govemment of the Federation of Malaya had meanwhile given notice that it intended to cease to contribute to the recurrent
expenditure of Scheme C.D. & W. (R) 440 as from 31st March, 1957. From that date, therefore,
recurrent funds would be insufficient to nlO and maintain the ship.
After the loss of her captain the Manihine returned to Singapore in September, 1956. Mr.
James Noble, the Chief Mate, took over command of the vessel but it was not considered practicable to recruit a certificated mate for the six months remaining until the termination of the
scheme on 31st March, 1957. Since by the terms of the Merchant Shipping Ordinance of the
Colony of Singapore the ship could not go to sea without a certificated mate it was decided to lay
her up. She was laid up to an Admiralty buoy at Loyang on 2nd October, 1956. In December,
1956 instructions were received from the Secretary of State for the Colonies for the transfer of
the Manihine to the service of the East Mrica High Commission for duty with the East Mrican
Marine Fisheries Research Organization, Zanzibar. She sailed from Singapore on 22nd April,
1957 and arrived in Mombasa on 15th May .
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TEMPERATURE AND SALINITY OBSERVATIONS
TEMPERATURES AT various levels were taken by the biologists on cruises Nos. 4 to 12 and
water samples for salinity determination on cruises Nos. 6 to II. No hydrologist was borne on
the staff.
On cruise 4 a pair of N.P.L. tested Negretti & Zambra protected reversing thermometers
was mounted on an Ekman reversing frame and used for all temperature observations. On
cruises 5 to 12 the thermometers were mounted on the Kundsen reversing water bottle with which
the water samples were collected.
Temperature and salinity observations were taken as a general rule at o· 5, 10, 30, 60, 80, 90,
120 m. according to the depth of the sea at the point of observation. The deepest temperature
observations were taken off the Borneo coast (Stns. 5/18 and 5/19) at 150 and 200 m. respectively
and in the Malacca Straits over the continental slope (Stn. 7/15) at 165 m. The deepest salinity
observations were taken in the South China Sea over the continental slope (Stn. 10/32) at 117 m.
and in the Malacca Straits over the continental slope at 165 m. (Stn. 7/15).
Temperature and salinity observations were usually taken in conjunction with trawling
stations. The salinities were determined ashore by Mr. J. H. Wickstead using the Knudsen
method with standard sea water supplied by the Laboratoire Oceanographique, Copenhagen.
Water samples were collected in the standard sampling bottles with porcelain spring-clip tops
sealed by rubber washers.
In Charts Nos. 15 and 16, which show the positions at which the otter trawl was operated in
the South China Sea and the Straits of Malacca respectively, the dark circles indicate the positions
at which temperature and/or salinity and/or plankton observations were made.
It is not intended to publish a detailed station list of temperature and salinity observations.
A list has been deposited at the Raffles Museum, Singapore, and the National Institute of
Oceanography, Wormley, Surrey, England, and may be consulted by arrangement.
PERPUSTAKAAN
NEGARAMALAYSI
A
3
THE SOUTH CHINA SEA
The area of the South China Sea covered by the Manihine's cruises consists of a shelf sea with a
gently sloping, slightly undulating floor. The shelf extends for a distance of approximately 420
miles in a north-easterly direction from the entrance to the Singapore Strait to the 100 fathom
line in the neighhourhood of longitude 109°E., which marks the edge of the continental shelf.
Here the slope descends more steeply and depths of 300 to 500 fathoms are found within a
distance of 15 miles from the position of the 100 fathom line. The continental shelf runs S. S .E.
between longitudes 109° and lIo°E. In about lat. 6°30'N it begins to turn S.E. and bends round
until in about lat. 5°30'N and long. 110°30' E it runs north-eastwards parallel to the Borneo
coast and about 100 miles distant from it for about 130 miles to the Luconia Shoals. These form
an extensive group of coral reefs in approximately long. 112°30'E. East of the Luconia Shoals the
shelf takes a southerly turn and approaches the coast of Borneo. Opposite Tanjong Baram it
turns N.E. once more and runs parallel with the Borneo coast at a distance of between 30 and 40
miles, continuing thus to the north-eastern extremity of Borneo and to the coast of Pelawan.
LAT.·N.B
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CHART 1. S.W. South China Sea. Contour lines on the continental shelf, drawn at intervals of
10 fms. from 10 to 100 fathoms. Letters indicate the character of the bottom according to samples
examined during the survey.
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Chart 1 shows the contour lines, drawn at depth intervals of 10 fathoms, on the shelf area. It
is seen that a low ridge runs north-eastwards with a depth of less than 30 fms. connecting the
coast of Malaya with the Anambas Islands. This continues as a broader and lower ridge with
depths of 30 to 40 fms. embracing the Great and North Natuna Islands and the small island of
Midai. A shallow trough having a depth of 40 to 50 fms. nms from N.E. to S.W. into the Carimata Strait between the North and South Natuna Islands.
Between the coast of the Malay Peninsula and the Great Natuna Islands the slope of the
shelf is very gradual. From Pulo Tioman on the 20 fathom line to the 50 fathom line east of
Great Natuna Island is a distance of about 280 miles. East of Great Natllna the slope is much
steeper and the distance from the 50 to the 100 fathom line is only 60 miles.
This area of sea lies under the influence of the south-west and north-east monsoon winds.
The former blows from May to September inclusive, and the latter from November to March.
In the intervening months of October and April winds are variable. During the height of the
north-east monsoon in January winds in excess of Beaufort force 4 are of frequent occurrence
and blow for long periods. During the months of the south-west monsoon winds of more than
Beaufort force 3 are seldom met with. In the intervening periods of about four weeks during May
and again during October variable winds with calms often occur.
The circulation of the surface waters over the South China Sea, together with monthly means
of sea surface temperature and wind force, have been depicted in the charts published by
Koninklijk Nederlands Meteorologisch. Instituut, by the British Admiralty and by the U.S.
Hydrographic Office (Ref. K.N.M.I., 1935; British Admiralty, 1950, U.S. Navy, 1945). These,
however, are all surface data and no data seem to be available for the subsurface layers.
Wyrtki (1957) has charted the currents at the surface of south-east Asian waters between
0
lat. 25°N and 20 S, and between long. 85°E and 143°E, in a series of 6 charts, one for every
second month of the year. The direction of the surface currents is indicated by arrows and the
speed in cms. per sec. by their character and thickness. The charts show that during the months
of the north-east monsoon a surface current flows southwards down the coast of Indo-China
and Malaya into the Carimata Strait and Java Sea. Off the coast of Malaya in the neighbourhood
of Pulo Tioman during February this southward current is depicted as having a maximum
speed of 50 cms. per second (I knot). During the months of the south-west monsoon the surface
current flows in the reverse direction northwards along the coast of Malaya and Indo-China,
attaining a maximum speed of 50 cms. per second over a wider area between the coast of Malaya
and the Anambas Islands. Off the northern coast of Borneo an eddy current flows S.W. along
the coast during most of the year except the months August to October, the end of the S.W.
monsoon period. In the neighbourhood of Great Natuna this current has a speed of 25 cms. per
second (t knot approx.) and turns in a clockwise direction N.E. to run counter to the main
southward flowing monsoon current. This clockwise system breaks down in June when the S.W.
monsoon is well under way and is replaced by an anticlockwise eddy east of the Natuna Islands.
During August and October, therefore, a current flows north-eastwards with a speed of about
2 knots along the coast of North Borneo.
PERPUSTAKAAN
NEGARAMALAYSI
A
TEMPERATURES, SURFACE
Surface temperatures taken on cruise 5 (Nov. 1955) and cruise 6 (Jan. 1956) are shown in
Chart 2. The approximate positions of the 28°C isotherm in November and of the 27°C isotherm
in January can be drawn. In both cases the positions agree well with the mean positions for these
two months figured in the charts of the Koninklijk Nederlands Met. Inst. The outhward movement of colder water from the South China Sea to the Carimata Strait in these months of the
N .E. monsoon is indicated.
Observations on cruise 8/9 (March-April, 1956, Chart 2) show that by the beginning of the
S.W. sea on surface temperatures had already risen above 28°C over most of the area. The
movement of the 28°C isotherm from its November position (Chart 2) eastwards to a northsouth position west of Great N atuna indicates the return northward flow of warm water from the
5
THE SOUTH CHINA SEA
The area of the South China Sea covered by the Manihine's cruises consists of a shelf sea with a
gently sloping, slightly undulating floor. The shelf extends for a distance of approximately 420
miles in a north-easterly direction from the entrance to the Singapore Strait to the 100 fathom
line in the neighb.o urhood of longitude I09°E., which marks the edge of the continental shelf.
Here the slope descends more steeply and depths of 300 to 500 fathoms are found within a
distance of 15 miles from the position of the 100 fathom line. The continental shelf runs S.S.E.
between longitudes 109° and lIOoE. In about lat. 6°30'N it begins to turn S.E. and bends round
until in about lat. 5°30'N and long. II0030' E it runs north-eastwards parallel to the Borneo
coast and about 100 miles distant from it for about 130 miles to the Luconia Shoals. These form
an extensive group of coral reefs in approximately long. 1I2°30'E. East of the Luconia Shoals the
shelf takes a southerly turn and approaches the coast of Borneo. Opposite Tanjong Baram it
turns N.E. once more and runs parallel with the Borneo coast at a distance of between 30 and 40
miles, continuing thus to the north-eastern extremity of Borneo and to the coast of Pelawan.
LAT.° N.B
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CHART I. S.W. South China Sea. Contour lines on the continental shelf, drawn at intervals of
10 fins. from 10 to 100 fathoms. Letters indicate the character of the bottom according to samples
examined during the survey.
4
12
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f.
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I
Chart I shows the contour lines, drawn at depth intervals of 10 fathoms, on the shelf area. It
is seen that a low ridge nms north-eastwards with a depth of less than 30 fins. connecting the
coast of Malaya with the Anambas Islands. This continues as a broader and lower ridge with
depths of 30 to 40 fms. embracing the Great and North Natuna Islands and the small island of
Midai. A shallow trough having a depth of 40 to 50 fins. runs from N.E. to S.W. into the Carimata Strait between the North and South Naruna Islands.
Between the coast of the Malay Peninsula and the Great Natuna Islands the slope of the
shelf is very gradual. From Pulo Tioman on the 20 fathom line to the 50 fathom line east of
Great Natuna Island is a distance of about 280 miles. East of Great Natuna the slope is much
steeper and the distance from the 50 to the 100 fathom line is only 60 miles.
This area of sea lies under the influence of the south-west and north-east monsoon winds.
The former blows from May to September inclusive, and the latter from November to March.
In the intervening months of October and April winds are variable. During the height of the
north-east monsoon in January winds in excess of Beaufort force 4 are of frequent occurrence
and blow for long periods. During the months of the south-west monsoon winds of more than
Beaufort force 3 are seldom met with. In the intervening periods of about four weeks during May
and again during October variable winds with calms often occur.
The circulation of the surface waters over the South China Sea, together with monthly means
of sea surface temperature and wind force, have been depicted in the charts published by
Koninklijk Nederlands Meteorologisch. Instituut, by the British Admiralty and by the U.S .
Hydrographic Office (Ref. K.N.M.I., 1935; British Admiralty, 1950, U.S. Navy, 1945). These,
however, are all surface data and no data seem to be available for the subsurface layers.
Wyrtki (1957) has charted the currents at the surface of south-east Asian waters between
0
lat. 25°N and 20 S, and between long. 85°E and 143°E, in a series of 6 charts, one for every
second month of the year. The direction of the surface currents is indicated by arrows and the
speed in cms. per sec. by their character and thickness. The charts show that during the months
of the north-east monsoon a surface current flows southwards down the coast of Indo-China
and Malaya into the Carimata Strait and Java Sea. Off the coast of Malaya in the neighbourhood
of Pulo Tioman during February this southward current is depicted as having a maximum
speed of 50 cms. per second (I knot). During the months of the south-west monsoon the surface
current flows in the reverse direction northwards along the coast of Malaya and Indo-China,
attaining a maximum speed of 50 cms. per second over a wider area between the coast of Malaya
and the Anambas Islands. Off the northern coast of Borneo an eddy current flows S.W. along
the coast during most of the year except the months August to October, the end of the S.W.
monsoon period. In the neighbourhood of Great Naruna this current has a speed of 25 cms. per
second (t knot approx.) and turns in a clockwise direction N.E. to run counter to the main
southward flowing monsoon current. This clockwise system breaks down in June when the S.W.
monsoon is well under way and is replaced by an anticlockwise eddy east of the Naruna Islands.
During August and October, therefore, a current flows north-eastwards with a speed of about
2 knots along the coast of North Borneo.
PERPUSTAKAAN
NEGARAMALAYSI
A
TEMPERATURES, SURFACE
Surface temperatures taken on cruise 5 (Nov. 1955) and cruise 6 (Jan. 1956) are shown in
Chart 2. The approximate positions of the 28°C isotherm in November and of the 27°C isotherm
in January can be drawn. In both cases the positions agree well with the mean positions for these
two months figured in the charts of the Koninklijk Nederlands Met. lnst. The outhward movement of colder water from the South China Sea to the Carimata Strait in these months of the
N .E. monsoon is indicated.
Observations on cruise 8/9 (March-April, 1956, Chart 2) show that by the beginning of the
S.W. season surface temperatures had already risen above 28°C over most of the area. The
movement of the 28°C isotherm from its November position (Chart 2) eastwards to a northsouth position west of Great Natuna indicates the return northward flow ofwaIlII water from the
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