SOME ASPECTS OF T H E BIOLOGY OF T H E RIBBONFISH TRlCHiURUS
HAUMELA(Forskal)*
BY M . S. PRABHU(Central Marine Fisheries Research Station, Mandapam Camp)

I.
II.

III.
IV.
V.
VI.
VII.

VIII.
IX.
X.
XI.
XII.

XIII.
XIV.
XV.

CONTENTSPAGEINTRODUCTION . .
..
..
..
MATERIAL AND METHODSTHE GENUS Trichiurus IN INDIAN WATERS ..
DISTRIBUTION..
MATURATION OF GONADS AND SIZE AT FIRST MATURITY
SPAWNING PERIOD, ITS DURATION AND OCCURRENCE OF YOUNGONESAGE AND GROWTH
LENGTH-WEIGHT RELATIONSHIPCORRELATION BETWEEN SIZE OF FISH, WEIGHT OF OVARY ANDFECUNDITY . .
GROWTH RATE OF GONADS..
..
..
FOOD AND FEEDING HABITSDISCUSSIONSUMMARYACKNOWLEDGEMENTS
REFERENCES

132
133
133
134
13.
139
143
146
148
150
153
158
160
161
161

I. INTRODUCTION
RIBBON fishes of the genus

Trichiurus occupy an important place among
Indian marine fishes judged by the magnitude of the fishery they support.
Delsman (1926) gave an account of six kinds of eggs and larvae of this genus
from Java Sea. Chacko (1950) reported the occurrence of eggs and larvaeof T. (?) savala from waters around Krusadai Island. Tang and Wu (1936)
published a preUminary note on the spawning ground of T.Japonicus in
Poi-hai, Gulf of ChihU. Prabhu (1950) gave a short account of the breeding
habits of T. haumela. Venkataraman (1944) and Chidambaram andVenkatraman (1946) dealt with the feeding habits and natural history respectively. Jacob (1949) published some notes on their bionomics. In adetailed work on the food and feeding relationships of thefishesof Singapore,* This paper formed part of a thesis submitted to the University of Madras for the
degree of Master of Science,132

Biology of Ribbon Fish Trichivju^ haumela {Forskdl)|33

Than% Ab Kow (195Q) ^lasi djescribed the feeding habits of T. haumela.
|i?ceftl){, Vijayaraghavan (1951) has published the results of a quantitativeand qi^tative analysis of the stomach contents of T.haumfk and T.sayala
at Madras. Mahadevan (193PJ( has (|e?cribed the histology of the aHmentarytract of Thgmiela. Devanesan and Chidambaram (1948) have enumerated
in a brief account, certain points of fisheries interest in these species in thg
Bi^adras State. With a vieAv to obtaining accurate information on the fishjery
biology of T. haumela, the most common Madras species, a Retailed iayesti^tion on this species was taken up at M^idras during 1947-49 and the results
obtained were supplemented, by further observations during subsequent
years.
11.

MATERIAL AND METHODS

A representative sample of 15-20fishwa,s collected each time at regular intervals, often from thefish-landingplaces or, \yhfn this was not possible, from fish
markets at Madras, Calicut, Quilandy and Mangalore during the years 1947 to1949, As soon as the specimens were brought to the laboratory, they were
measured and sorted into different size groups. The ^nads were dissected out
and examined in detail to study the different stages of maturity. Thp guts were
removed and fixed in 5% foitnalin and later examined for the gut-contents, thevolume of which was determined by the displacement method. Ova, teased out
from fresh ovaries or in prepared sections of ovaries, were measured with the helpof an ocular micrometer giving a magnification of 16-7 ju to each micrometer
division. In studying the otoliths, the method suggested by Nair (1949) was
employed. In determining the number of ova in each ovary, weighed portionsof ovaries were teased in water or boiled in water for 2-3 minutes and then theova separated to count the number of maturing ova. Hickling's (1940) methodof fixing weighed portions of ovaries and then teasing them and counting was
found to be more time-consuming and hence that method was not followed.
From the number of ova in the known weight of the ovary, the total number of
ova in the whole ovary was calculated.
III. THE GENUS Trichiurus IN INDIAN WATERS
The fanuly Trichiurida consists only of the single gpnm Trichiuruji whi^h
COM be easily identified by i^s elongated, ribbon-shap?d and lateraUy qompressed body tapering towards the posterior end (Plate IJI, a). Tbeirf is
no caudal fin. The dorsal fin extends from the hind edge of the preopercle
along the whole of the back and is many-rayed. Yentrals are in the formof scales and anal spines are nuritite an^ s^jmetimes concealed under theskin. The entire body is scaleless and is ?oated with £i shining silvery substanQe. The cleft of the mouth is dfep wittt teeth in jaws and palatines,
those on the premaxillaries being arched and strong. The lateral teeth arelancet-shaped- Lateral line is just b«l,ow the middle of the body and isvery clear.

134

INDIAN JOURNAL OF HSHERIESThe genus Trichiurus is represented in the Indian seas by three species
T, haumela, T. savala and T. muticus. The chief characters by which thethree species can be identified quickly in the field are given in Table I.
In Madras the three species, T. haumela, T. savala and T. muticus, are popularly called ' Olai valai', ' Kartigai valai' and ' Savalai' respectively. Ribbon
fishes in general are known as ' Savallu' in Telugu, ' Pambole' in Canarese,• Pituirkti' or ' Pitiwagti' and ' Bala' in Marathi and ' Thalayan' or' Pambada ' in Malayalam.
IV.

DISTRIBUTION

The ribbon fishes have a wide range of distribution throughout thewarm seas. Besides being landed at several places along the eastern andwestern coasts of peninsular India, T. haumela has been known to be themost common species occurring in the Indian Ocean, around the Archipelago and in various parts of the Pacific.
As stated by Goode (1884), some writers believe T. haumela of the Indo-Paciflc
region to be identical with T. lepturus found in the tropical Atlantic, on the coastof Brazil, in the Gulf of California, the West Indies, the Gulf of Mexico and northof Woods Hole, Massachusetts, and he states that this species occurs also on the
coast of Europe as also in Southern England where they occur abundantly, butthey do not however enter the Mediterranean. Various foreign authors such as
Fowler (1903-43), Higgins (1921), Cornish (1867-72), Clogg (1871), Gatcombe(1871 and 1876) and Herre (1940) have recorded the occurrence ofribbonfishes
in the Indo-Pacific and Atlantic regions. T. lepturus (Linnaeus) which is very common along the American coasts, described by Fowler (1904), does not vary muchfrom T. haumela (Forsk.) described by Day (1889). Fowler (1904) while describing T. haumela collected from Sumatra says that this species is closely related toT. lepturus (Linnaus) differing apparently in the less numerous dorsal rays andthe deeper body. He further states that T. haumela has been recorded a numberof times from India although Day considered his T. malabaricus as identical.
In the Indian waters the three species shoal separately at different places.
On the east coast T. haumela predominates in the catches at Madras andin north Andhra, i.e., in the fishing centres north of Visakhapattinam.
T. savala has been reported to be more comtnon on the coast of central
Andhra, i.e., Visakhapattinam to Masulipattam; whereas in the south near
Gulf of Mannar and Palk Bay, in addition to T. haumela and T. savala which
occur in very small numbers, the third species T. muticus is also quite common.
In the southern part of west coast consisting of Travancore-Cochin and Malabar and in the northern part comprising the Konkan, Bombay and Ratnagiri
coasts, T. haumela and T. savala respectively are the common species caught.** This information is partly based on tlie reports of the fishery survey assistants of the
C.M.F.R. Station working along the east and west coasts of India.

TABLE IShowing the Chief Characters by which the Three Species can be Quickly Identified in the Field
T. haumela

T. savala

T. muticm

1. Lower jaw considerably longer than Lower jaw considerably longer than Lower jaw more prolonged than theupper jaw.
the upper jaw.
the upper jaw.
2. Dorsal profile, between end of
snout and eye, rather concave.

Interorbital space nearly flat.

Interorbital space with a keeled ridge.

S,"* Medium number of dorsal rays.
" (127-33)

Smallest number of dorsal rays.
(112-20)

Largest number of dorsal rays.
(140-50).

4.^The longest rays in the middlei of Longest dorsal rays equal to height Longest dorsal rays equal to onlyh^f height of body.
the dorsal fin equal to height ofof body,body.
5. No rudiment of ventrals.

No rudiment of ventrals.

Ventrals indicated by two smallrounded scale-like projections on
the lower surface of the abdomen.

6. Anal fin in the form of short spines. Anal fin in the form of short spiaes, Anal fin almost or entirely concealed
under the skin.
often concealed or blunted atoften distinct, especially the first
their extremities,
which ik twice as long as in T.
haumela.
7. Lateral line gradually descends until Lateral line passes downwards to the Lateral line almost straight and a little
below the middle of the body
above the commencement of thelower third of the side,
especially in the last part of theanal fin where it is in the lower
course.
third of the body.
8. Upper half of the body rendered Silvery. Fins yellow-white.
dark by numerous black dots.
Fins pale yellow.

Burnished silyer. Fins yellowish.

5"

3

Ii
CO.

SB

s

I

136

INDIAN JOURNAL OF FISHERIES

Delsman (1929) states that out of the nine species enumerated by
Bleeker, only six occur in the Indo-Australian seas, and of these the best
known is T. haumela. From the observations made during the present
investigation, it has been found that T. haumela is the most common species,
occurring along the coasts of Madras State, although occasionally T. savala
and T. muticus are also caught from certain restricted regions.'
V.

MATURATION OF GONADS AND SIZE AT FIRST MATURITY

Structure of ovary.—The ovary in T. haumela is located just above thealimentary canal in the abdominal cavity and is bilobed. The two lobes
are asymmetrical in length as well as in girth (Figs. 1 and 2) and they appear

DorsalVentralS
S

Oviducts
FIG. 1. A cross section of the ovary.
FIG. 2. Ventral view of the asymmetrical lobes of the ovary of T. hi'umela.

Biology of Ribbon Fish Trichiiirus. haumela (Forskdl)

137

to be in the form of a U-shaped loop of which the left forms a part of one
limb and is nearly two-thirds the length of the right one. The two lobes
are fused together along the dorsal edges of their adjacent sides and aresuspended from the dorsal wall of the abdominal cavity by a thin mesovarium.
The ovary is of the cystoarian type and the internal structure is of thepattern found in the ovaries of most teleostean fishes. In the ovigerous
lamellas, the mature ova are usually located away from the ovarian walland towards the centre of the ovarian cavity. During the spawawg
season, the ovaries get distended and ova burst out from the follicles andlie in the lumen of the ovary, to b? subsequently shed during the spawningseason.
Stages of maturity.—The ovaries of T. haumela in various stages ofmaturity show a gradation which is found to be characteristic of thisspecies. A scale of only five stages of-maturity is found practicable forT. haumela as against the seven stages followed by the International
Council for the Exploration of the Sea. These may be labelled as' immature', ' maturing', ' mature', ' spawning' and ' spent'. A comparison, as is made below, will show that the third 'mature' stage ofgonads in the fishes studied was equivalent to the III, IV and V stages of
the International Council.
Stages followedby the I.C.E.S.
Stage•
I. Immature .. Testes slender and transparent, ovaries
slender, transparent, eggs not visible to
naked eye ..
..
..
..

I

II. Maturing .. Testes slightly enlarged, opaque, ovaryslightly enlarged, eggs having granularappearance (includes gonads in rematuring condition after spawning)

II

III. Mature.. Testes greatly enlarged, pale-white, ovaries greatly enlarged, yellowish, eggs
visible to naked eye ..
..
.. Ill, IV and V
IV. Spawning .. Not observed
..
..
..
VI
V. Spent.. Testes loose, opaque, few sperms, either
motile or non-motile, ovary flabby,
contracted, showing traces of haemorrhage, eggs granular in appearance,
few yolky eggs
..
..

VII

138

INDIAN JOURNAL OF FISHERIES

By a comparison offishesclassified according to the condition of gonads,
it was found that specimens with gonads immature enough to be considered
as of Stage I averaged round 42 cm., while those with gonads more matureand fit to be placed in Stage II averaged round 46 cm., and those with still
more mature gonads and deemed to fit into Stage III measured 48 cm. However, fishes with gonads in fully spawning condition (Stage IV) have notbeen observed among the 976 ripe specimens examined, whereas those withgonads showing all the characteristic features of being in a spent condition
were found to be measuring more than 48 cm. An examination of thematurity groups obtained by such a classification on the basis of size showedalso clear and well marked differences in the sizes of the ova.
TABLE IIShowing the Average Size of the Largest Eggs and the Range in Size ofSpecimens in Different Stages of Maturity
Stages ofmaturity

Range in size of
specimens

Average size of thelargest eggs

I

up to 42 cm.

0-22 mm.

11„

46 cm.

0-4 mm.

III„

48 cm.

1 • 1 mm.
Ovaries in this stage have not been
observed
0-56 mm. (in spent ovaries)

IV
V

above 48 cm.

In Table II the diameters of the intra-ovarian eggs are also given inorder to assess the maturity of the gonads more correctly than by mere description. As will be seen from the table, the eggs increase in size markedly
in Stage III, when they are of maximum diameter.
Minimum size at first maturity.—To determine the size at which
T. haumela mature, the data collected on the condition of gonads of 976
specimens studied during a continuous period of 12 months were analysed
and tabulated (see Table III).
It is obvious from Table III that individuals up to a length of 37 cm.
are immature and that in the next size group also, i.e., 37-41 cm., the majorityof the fishes are in Stage I. In the following size group, i.e., 41-45 cm., thepercentage of maturing individuals has increased to 91, whereas in the nextBiology of Ribbon Fish Trichiurus haumela (Forskdl)

139

TABLE IIIShowing the Percentages of Gonads ofT, haumela in Different
Stages of Maturity
Percentages of gonads in each stage of maturity
(cm.)

I

17-21
21-25
25-29
29-33
33-37
37^1
41-45
45-49
49-53
53-57
57-61

100
100
100
100
100
74
9

II

III

».

»,

V

..
.*

.

•

.

•

•

26
91
51

,,
,,
••

IV

43

78
59
75

6
22
41
25

size group individuals with gona;ds in Stages II (including those in rematuringcondition—Plate III, b). III and V also occur. The occurrence of specimens
with gonads in Stage V (spent) for the first time in this size group clearly
indicates that T. haumela begin to spawn when they attain a length somewhere between 45-1 and 49 cm. From Table II it could be seen that thelarge intra-ovarian eggs of 1 • 1 mm. are first found in the ovaries of individuals of 47-48 cm. in length. As the smallest specimens with spent ovaries
measured 47-48 cm., it is clear that the minimum size at which T. haumela
mature is 47-48 cm.
VI.

SPAWNING PERIOD, ITS DURATION AND OCCURR^ICE OF
YOUNG ONESThe conspicuous absence of ribbonfisheswith fully ripe gonads (Stage IV)along the coastal waters and the reappearance of thesefishwith spent gonads,
suggest that they spawn in the offshore waters. The concludon is supportedby the fact that so far neither developing eggs nor larvie of T. haumela havebeen collected from the coastal plankton samples except the two post-larvae
obtained by Nair (1952). He says that though this fish occurs in hugeswarms, the post-larval stages are extremely rare in the Madras plankton
and that so far only two specimens have been obtained. One in September
aM the other in December 1944. Further, he states that the extreme rarity

140

INDIAN JOURNAL OF RSHERIESof the post-larval forms may be due to their oceanic habitat. The occurrenceof gravid specimens measuring 48 cm. and above during the months of April
and May and their reappearance in large numbers in spent condition in July,lead to the conclusion that the spawning should have taken place in theinterval. Systematic data gathered on the condition of gonads in mature
specimens for a continuous period of 12 months show that fishes with gonads
in spent condition (Stage V) begin to appear from the month of July thereby
indicating that the spawning must have taken place towards the end of June
and that the spawning is probably restricted to a definite and short period.
The above inference is confirmed by a study of the diameters of the intraovarian eggs carried out on the lines suggested by Hickling and Rutenberg (1936)
and De Jong (1940). From each ovary nearly 1,000 ova in all stages of development were measured, and another set of measurements were made from random
samples of ova collected from 8 different ovaries. Thus about 1,000 ova eachwere measured from mature ovaries of specimens 48-0, 50-7, 53 -3 and 54-0 cm. in
length and other measurements were made from ovaries of 8 different individuals
ranging in size from 48 to 55 cm. Altogether about 5,000 ova were measured.
The entire range in size of the ova was then divided into several 5 m.d.* size groups
and the percentage number of ova in each size group was calculated. The datathus derived are shown in Fig. 3. Similarly, more than 1,000 intra-ovarian eggs
each from two spent ovaries of individuals 55-7 and 57-5 cm. in length were alsomeasured and the data are shown in Fig. 4 to enable easy comparison of the frequencies of ova in spent and mature ovaries. The degree of formation of yolk in maturing and mature ova was taken as a reliable guide in judging the stages of maturityof the intra-ovarian eggs. The diameters of ova varied from 5 to 75 m.d. A
microscopical examination of the intra-ovarian eggs in mature ovaries (Plate III, c)revealed that all ova measuring 30 m.d. and above were fully yolked and matureand those measuring less than 30 m.d. immature. From Fig, 3 it could be seenthat there are at least 2 distinct modes, mode ' a ' representing the mature stockof ova and mode ' />' the immature ova and that the mature ova are more or lesssharply differentiated from the immature ones. The fact that the maturing eggs
are sharply differentiated from the immature stock of ova makes it probable thatthe spawning is restricted to a definite and short period. Jacob (1949) suggests thepossible occurrence of two spawning seasons of a single prolonged one. The
present observations do not support this suggestion. Moreover studies on the
spawning habits indicate that not only is the spawning period restricted to a shortand definite period but also that spawning takes place only once a year
probably at the end of June. Young ones of this species measuring 7-9 cm. in
length have been observed in large numbers only once a year towards the end of* (m.d. represents micrometer division. In the graphs, a scale is also given for easy
conversion o£ m.d. into mm. With a view to avoid giving diameters of ova in fractions ofmm. the measurement of ova are given in m.d.)Biology of Ribbon Fish Trichiurus haumela (Forskdl)

141

July in the fish-landing places along the Madras coast as well as at Attankarai andThangachimadam along the Ramnad coast. Thus it is quite probable that the
post-larvae of T. haumela grow to a size of 7 to 9 cm. in length within a period ofa month and a half. This observation agrees with that of Tang and Wu (1936)

20
15
10
5
0
20
15
10
5
0^ 20

I

1 15
t

10-

0«^ 201510020
15
105-

IV

Average of I, II, m & IV
Percentage of Ova from 8 diff.
aOvaries

1-5 ' 10^15 20^25 ' 30-35' 40^45 ' 50^55 ' 60-65 7 M{MicromHer Divisions)' 01 o'^ O'S 0'4 O's iy& o'-7 Q'fe 6'5 I'O I'l i'2 I's(MUUmeters)
Diameter of Ova
FIG. 3. Frequencies of ova in mature ovaries of T. haumela in different size grou.3?.
Curve I. Percentages of ovi from a fish 50-7 cn>. in length
Curve II.
„„„ 53'3 cm.
„
Curve III.
„„„ 54'0 cm.
„
Curve IV.
„,,„ 48'0 cm.
„

142

INDIAN JOURNAL OF FISHERIFS

>
o
o
Xi

B
a
c

(U

sa

o0)
>1

<u

1-5

10-15

01

0-3

20-25 30-35 40-45
Micrometer divisions

50-55

60-65

0-5
07
Millimeters
Diameter of ova

0-9

TT

70-75

FIG. 4. Frequencies of ova in two spent ovaries of fishes 55-7 cm. (curve I) and 57-5 cm.
(curve II) in size and mature ovaries (curve III) of 8 different fishes ranging in size
from 48-55 cm.

who have reported that eggs of T. japonicus give rise to post-larvae of 5 4 to 9-5
cm. in length within a period of a month and a half from the time of spawning.

Biology of Ribbon Fish Trichiurus haumela (Forskdl)

143

From a comparison of the curves I and II with that of curve III (Fig. 4), it isevident that in spent ovaries, eggs above 30 m.d. are not at all represented, thereby
indicating tliat the entire stock of ova above 30 m.d. are shed during spavming.
It can be concluded that the range in size of ova shed during spawning season isfrom 30 to 75 m.d.
VII.

AGE AND GROWTH

Ribbon fishes being scaleless, age determination has been attempted
only by studying the otoliths and length frequencies.
Otolith studies.—Nearly 126 dtoliths of T. haumela of different sizes(10 1-63-5 cm.) were studied. It was, however, interesting to note thatgrowth rings were absent in almost all the otolithis. An examination of afew otoliths from fishes belonging to the other two species, namely, T. savala
and T. muticus, indicated, that they also had otolithis of the same character.
In ahnost all the otoliths of T. haumela, a narrow strip of area along theperiphery alone was found to be translucent and this area is probably thezone where fresh calcification is taking place. Even by employing themethod of clearing and mounting the otoliths suggested by Nair (1949), it
was not possible to make out any growth checks.
Though growth rings are absent in the otoUths, the length, width andthickness of otoUths show a gradation which corresponds with the lengthof the fishes. The otoliths dissected out from each individual was measured
and the entire range in size of the individuals was divided into several 10 cm.
size groups aiid the size of the otoliths in each size group was ailculated(Table IV).
TABLE IVShowing the Number of Otoliths Examined and Their Average Sizein Different Size Groups
Size groupsof specimens(cm.)

Number ofotoliths
examined

Average size ofthe otoliths
(mm.)

10-20
20-30

11
11

30-40
40-50
50-60
60-70

28
37
31
S

1-64
2-35
3-13
400
4-67
5-90

144

INDIAN JOURNAL OF FISHERIESIt may be seen from Table IV that the rate of increase in length of otoliths in the various size groups is more or less gradual and somewhat proportional to the length of the fish.
Size frequency distribution.—1,05^ specimens of T.haumela were examined between March and July 1952. Every week during this period, about
100fishwere taken from the fish haul and sorted into 12 different size groups,
each having a length-range of 4 cm. and the number of fish belonging toeach size-group was noted and the percentage also calculated. The datacollected during the weeks of each month were averaged and taken as
typical for the month (Fig. 5).
A

B

July 1952

D

klllhlll

25

-tn
h

June 1952

May 1952!••.

April 1952••••••.
302520
15
10-

March

Size Groups {in cm.)

FIG. 5. Showing the size frequency distribution in T. hmmela from March to July 1952.

Biology of Ribbon Fish Trichiurus haumela (Forskdl)

145

In March it was found that the first six size groups ranging from
8-32 cm. were not at all represented whereas the last size group, i.e.,
52-56 cm. formed 3-85% and the two size groups 44-48 cm. and 48-52 cm.,
formed 39-74% and 35-9% respectively. In April, the three size groups,
naffiely, 16-20cm., 28-32 cm. and 44-48 cm. forming 15-79%, 14-47% andl'l-%2>% respectively, were found to show three definite peaks while theiowfest and the largest size groups, namely, 8-12 cm. and 52-56 cm., wereabseht. In May, the size groups ranging from 44-56 cm. were absent but
two size groups, 12-16 cm. and 28-32 cm., constituted two clefiriite peaks.
The lowest size group, 8-12 cm., also formed about 9-27%. In June, thelowest size group was not present and the longest size group iformed only
0-16%. One size group, i.e., 16-20 cm., formed a definite peak, whereas
all the other size groups ranging from 20-52 cm. appeared to be gradually
decreasing in number. In July, excepting the lowest size group, i.e., 8-12 cm.,
all the others were found to be well represented. Pour size groups,
16-20 cm., 28-32 cm., 44-48 cm. and 52-56 cm., were found to constitutefoiit definite peaks.
From Fig. 5 it could be seen that there are at least fouir distinct ftiodes' a', ' *', ' c ' and ' d' representing probably four year-classes. The fiirstone, i.e., mode ' a ', is in the 16-20 cm. size group in the months of April,June and July and in the 12-16 cm. size group in May alone. As the mode
' a' has been found to be between 12-16 cm. only in one month, its occurence in 16-20 cm. for a longer pei-iod has been given conisideratioii. Them^M mode is in the 28-^2 <an. isize girolip, the third in the 44-48 cm. 8ife
glrdttp and the fourth in the 52-56 cm. size group. ConiSidering thit themIdMpoint measurementis of these four size groups are the average si^es tttaifie^
by individuate from their first to fourth year of life, it could be seen tftat ttte
flrist-year class specimens attain a length of 18 cm., the second-year cMss30«3n., the third-year class 46 cm. and the fourth-year class 54 cm. Thetefotie Wilttedividualsrepresented by mode ' a' inay be those hatdifed fromthe i^|s shed during the previous spawning season, i.e., June 1951, AM thfe
individuals represented by modes b\ ' c' and ' d' hatched out from eggs
shed during 1950,1949 and 1948 respectively. As the spawning in T. haumela
seems to take place at the end of June and because the first-year class withan average length of 18 cm. is found in large numbers in the month of April,a growth of nearly 18 crn. during the first year seems to be indicated. Following the same principle it could be seen that the growth during the second
year is about 12 cm., and during the third and fourth years 16 and 8 cm.
resfHScttve^. It is evident tiM the gi-0#th rate in ThmMett is fairfy high "dttttttg the first year, and slightly less dtt-iftt the secodd y6&r. The
^Wi
10

146

INDIAN JOURNAL OF nSHERIES

rate of about 16 cm. during the third year (which is more than the growthduring the second year), is probably due to some bias in the samples brought
about by the inshore migration of the different size groups. The mode
' C has been found to be quite prominent in the same size group, i.e.,
44-48 cm., during March, April, June and July. The rate of growth inlength during the fourth year was found to be only 8 cm., which is muchless than during the first, second and third years. Hence the findings ofBaranov (1916) and Ford (1933) that thefishesin general have an accelerated
growth during the first year and a lesser rate during the subsequent years,
seem to hold good in the case of T.haumela also. T. haumela has beenfound to attain sexual maturity and commence spawning at a length of
47-48 cm. which corresponds to the size attained by the third-year classindividuals. During the fourth year the rate of growth has been found to
be on the decrease. It is also obvious from Fig. 5 that the mature individuals in the 52-56 cm. size group and in all the size groups ranging from44-56 cm. disappear from the coastal waters in the months of April andMay respectively. Such an off-shore migration of mature individuals in
April and May and their appearance in small numbers in June and in larger
shoals in July in the inshore waters, seem to indicate that the mature individuals move away from the coastal waters probably for the purposes ofspawning.
VIII.

LENGTH-WEIGHT RELATIONSHIPThe length-weight relationship in T. haumela was determined bymeasurements on 174 specimens ranging in size from 12 to 56 cm. The total
range in size was divided into 11 size groups with a class interval of 4 cm.
and the mean length (' L') and weight (' W') in each size group were calculated.. It has been found that the length-weight relationship of most fish
can adequately be described by a formula W=AL^ where 'W'=weight,' L ' = length, ' A ' , a constant and ' ^', an exponent usually lying between
2-5 and 4 (Hile, 1936; and Martin, 1949). For all ideal fish which maintainthe same shape, the value for ' ^' has been found to be 3 (Allen, 1938).
The observed and the calculated values for ' W', when plotted against
their respective values for ' L ' (Fig. 6) indicate that there is close agreement between the observed and the calculated sets of values. Applying
the formula W = AL", the length-weight relationship formula was calculated
to be W= 0-0004935 L^-o^" Hence it is to be inferred that in T. haumela
the weight increases in proportion to its length showing the normal pattern.
As can be seen from Fig. 6, fishes up to 32 cm. in length increase inweight at a lesser rate than the subsequent size groups. This is further

Biology of Ribbon Fish Trichiuros haumela (Forskdt)

147

114
CaUaiated wt.
Dots represent observed wt.

Length of Fi^ (cm.)
FIG. 6. Calculated length-weight curve fitted to the average observed
values for T. haumela.

length-weightborne out by the observations on feeding (vide infra) that the maturing fishes
ranging in size between 42 and 48 cm. feed ravenously and increase, in weightout of all proportions to the increase in length.

148

INDIAN JOURNAL OF HSHERIESIX.

CORRELATION BETWEEN SIZE OF FISH, WEIGHTOF OVARYAND

FECUNDITY 'Size offish and fecundity.—The fecundity of any species of fish is usually
determined from the total number of ova forming a season's crop. While
studying the fecundity of the herring of the Southern North Sea, HickUng(1940) stated that in the herring, the large yolky eggs found in the maturingovary were the whole of the season's crop of eggs and a count of them gave
the absolute fecundity of the fish. Since the individuals of T. haumela
measuring more than 47-48 cm. seem to breed once a year and since allindividuals ranging in length from 47-62 cm. are capable of producing eggs,
an attempt was made to find out the relation that exsits between the rate ofincrease in length of a fish and numbers of ripe ova in its ovary. The values
obtained from 18 sets of observations on the number of eggs from fishesof different lengths with ovaries in maturing and mature conditions were
utilised.
The theoretical values for the number of eggs produced by individuals
in diff"erent size groups were calculated (Fig. 7). By the method of leastsquares, the formula which best expresses the relation between length andfecundity was calculated to be F = 0-0004119 L*-^'^ where ' F ' and ' L 'represent fecundity and length respectively. Hence the fecundity was foundto increase with length at a rate substantially greater than the fourth powerof the length. Smith (1947) found a straight line relationship between logarithms of number of eggs and lengths of fish in a study of their relationships for the eastern trout. Hickling (1940) found in the herring of theSouthern North Sea the rate of increase to be greater than the third powerof the length, and Farran (1938) found in the Irish herring the fecundity
increasing at the order of 4-5 power of the length. Thus the rate ofincrease in the fecundity of T. haumela could be compared to that in Irish
herring.
Weight of ovary and number of ova produced.—If the weights of the
gonads of diff"erent mature fishes are correlated with the total number of ova
they contain and a graph be drawn, it will show a relationship either identicalto that found between the length of fish and fecundity, or if the rate of growthin length of gonads in relation to the length of the fish is not directly correrelated {vide infra) the graph will show an entirely different type of relationship from that observed in the previous section.
As in the previous case, employing the method of least squares, theformula which best expresses the relation between the weight of the ovary
and fecundity was calculated to be F = 2526 W^-o'"*, where ' F ' and ' W

Biology of Ribbon F/s/j Trichiurus haumela {Forskdl)

20000

149

Length of ovary (cm.)
Observed No. of ova
Calculated No. of ova

I 15000
B
O

>
O
o
u

s 10000-

5000
Length of Fish (cm.)
FiG. 7. Showing the relation between the length offish and number of ova produced-

represent fecundity and wei^t respectively. The observed and the theoretical values for ' F ' in relation to weight of ovary are shown in Fig. 8, fromwhich it could be seen that the theoretical values are more or less in close
agreement with the observed values. This formula expressing the relation
tetween the number of ova and weight of ovary clearly shows that the numberof eggs produced has a very' close correlation to the mean weight of theovary. Thus the observations on T. hmmela are in agreement with theremarks of Hickling (1940) who has stated that, since the production of
eggs is the dominant function of the- ovary, a close correlation should
be expected between the wwght of the ovary and the number of e ^produced.

150

INDIAN JOURNAL OF FISHERIES:

Calculated No. of Ova
Dots represent observed No. at Ova

14000

i /

•

y^'

12000

1
^ ^

^10000
•o

8000

6000

<X^
vXT

4000

2-0

3-0

4-0
Weight of Ovary (gm.)

5-0

6-0

Fio. 8. Showing the relation between the weight of ovary and the number of eggs produced.
X.

GROWTH RATE OF GONADS

While it is probable that the size (or weight) of gonad is directly proportional to the size (or length) of fish during the maturing stages (as has
been indirectly inferred in previous sections), it will be of interest to know
how the size of the gonads in fishes is actually related to their length andhow the gonads in male as well as female are related to -the length of fisheven in immature forms. A study of the graphs given for males and females,
ranging in length from 18-62 cm., which includes specimens with gonads
in all stages of maturity, will show that the relationship is simple and direct.
The entire range in size of the 976 available specimens was conveniently
divided into 22 size groups with a class interval of 2 cm. in preparing Figs. 9
and 10. In calculating the theoretical values of the sizes of the ovaries aswell as testes, the mid-points of each size group were taken into consideration.
Female.—^To express the relation between two variates ' X ' and ' Y '(' X ' length of individual and ' Y ' of ovary), the equation for the regression
line Y= a + bX, where ' a' and' 6' are the constants (Pearson and Bennet,
1942) was used. In the case of ovary the equation was found to be
Y = - 0 - 6 8 0 6 + 0-1431X. When the observed values for ' Y ' wereplotted against their respective * X ' values, it could be seen that the points
are more or less closely located near the linear regression line (Fig. 9). From

Biology of Ribbon Fish Trichiurus haumela (Forskdl)

151

Calculated length
Dots represent observed length

- . 6
S

>
O

tS 4
e '

L I I

O-i,

I I 11

SSSS3S8§S^^;S^§8¥^¥WfSgS^st 04
Length of Fish(grouped into 2 cm. size groups)
FIG.

9. Showing the relation between lengths of fish and ovary in T. haumela.

the equation calctUated for the regression line, it could be inferred that forevery 10 cm. increase in the length of the fish, the length of the ovary,
increased approximately by 1-43 cm.
Male.—As in the case of female, when the observed values for ' Y '(length of testes) were plotted against their respective values for ' X ' thepoints were found to be located close to a linear regression line (Fig. 10).
Employing the same equation as before, it was foimd that Y = — 0'3765 +
0-1465X, where ' X ' is length of individual and ' Y ' of testis. In otherwords, 'for every 10 cm. increase in the length of the individual, the length

152

INDIAN JOURNAL OF FISHE^I^S

Calculated length
Dots represent theobserved length

s

5

-1.x.

JL-i.

J-Jm

Length of Fish(grouped into 2 cm, size groups)
Fip. 10. Showing the relation between lengths of fish and testes, in T. haumela,of the testis was found to increase approximately by 1-47 cm., that is to say,at a sUghtly higher rate than the ovary. This is in conformity with the viewof Hickling (1940) whp found; that the weight of tpstis incr^ses with Igngth
at a slightly higher rate than the ovary in the herring of the Sputhern Nprth.
Sea. I^ is interesting to note in this cpnnectipij. Hickling's pb^-v^tipn pn thfi
increase in weight; of testis and ovary in the young and. old, herring. He
fouled that while the mean weight of the testis is greater than that of thepyary an^ong the ypunger fish, the pvary is. heavier tb^n fhs testis, at apy

Biology of Ribbon Fish Trichiurus haumela (Forskdl)

153

given length among the older fish. He ascribes this discrepancy as probably
due to the simultaneous increase in weight of the permanent tissue of theovary.
XI.

FOOD AND FEEDING HABITS(a) Important items of food.—An exploratory examination of the gut
contents of a few showed that T. haumela is a carnivore as stated by Venkataraman (1944) and Vijayaraghavan (1951). In order to see if there was any
difference in the food of fishes of different sizes, detailed analyses were madeof the gut contents of 976 fishes of different sizes caught during the courseof a year. The food items were sorted out and identified fronn the mutilated
bits. A regular record was also kept to indicate the fishes, prawns andothers which occurred along with the ribbon fishes. A cOTSparison wasmade between the food items represented in the stomach and tbose available
in the vicinity to see if any selective feeding existed in thefishes,of different
sizes and ages (see table below).
During times of intensive feeding, mature and spent individuals of T. haumela
have been found with young and mutilated individuals of the same species in theiralimentary tract. This' cannibalism' does not correspond to a period when thereis lack of other species offishon which they feed, because, when shoals of ribbon
fishes migrate to the coastal waters from the month of July, Stolephorus spp.,
forming a favourite food, have been found to occur in large numbers in the coastal
waters. Similar case of ' cannibalism' has been recorded in the Bombay duck
{Harpodon nehereus) by Bapat, Banerji and Bal (1952) and Pillay (1952). On theother hand, it may be only due to overcrowding of the shoals. Venkataraman(1944) states that he found during September 1943, guts of ribbon fishes being
literally clogged with macerated fish eggs and he further states that this featuremight very greatly hit other fisheries; but during the course of the present study,
no fish eggs have been observed among the gut contents of T. haumela. Youngones of Sepia were found to constitute only a rare item of food.
Cestode larvae such as Tetrarynchus sp. and Gymnorynchus sp. were foundin the gut in large numbers only during the times of intensive feeding in matureand spent individuals. No cestode larvse have been found in the guts of immature
specimens.
It will be seen from the following table that though T. haumela feedindiscriminately, the food items shown in the second column of the following list have never been found in the guts of any of the specimens ofT. haumela.

154

INDIAN JOURNAL OF FISHERIES

Items found in the alimentarytract of T. haumela
Fishes :Hemiramphus spp.
Dussumieria spp.
Kowala coval
Mugil spp.
Caranx spp.
Sardinella spp.
Leiognathus spp.
Sciana spp.
Trichiurus spp.
Stolephorus spp.
Crustaceans:
Penceus spp.
Metapenaus dobsonii
Acetes spp.
Others:
Sepia
Silicoflagellata;

Fishes and other animals caught
along with T. haumela

Therapon theraps
Therapon puta
Pelates quadrilineatus
Pampeneus spp.
Upeneoides spp.
Rastrelliger kanagurta
Sardinella longiceps
Young ones of Chirocentrus dorab
and Cybiuin spp.

Nil

Nil

The present observations, therefore, do not support the conclusions
made by Venkatraman (1944) that the ribbon fishes do not exhibit any typeof selective feeding. Further, as will be seen from Table V, fishes ranging
in size from 17-45 cm. which are definitely not mature, show a tendency
to feed on prawns and small-sized fishes such as Stolephorus spp. and LeiO'
gnathus spp. though the smaller sized individuals of other species like
Parupeneus spp., Upeneoides spp., mackerel, dorab and oil sardine areavailable. It will also be seen that fishes of 46-62 cm. which are definitely
adult forms, feed on fewer prawns and smaller fishes than the young ribbon
fishes. Hence, though T. haumela is a complete carnivore, the species, to someextent, seems to be a selective feeder as is evident from a quaUtative analysisof the gut contents.
(b) Quantitative analysis and the seasonal variation of the gut contents.—
T. haumela die in the nets soon after capture and it is known that most fishes
in the throes of death, vomit a good part of the gut contents. Volumetricestimations of the gut contents will not, therefore, have much value in judging

Biology of Ribbon Fish Trichiurus haumela (Forskdl)

155

the variations in the degrees of feeding. Moreover, as a large number offishes had to be handled in a short time, the volumes of the different animalcomponents could not be estimated separately. Owing to these reasons
it was considered that a simple arbitrary assessment of the rate of feedingfrom the amount of food left in the gut would alone be satisfactory. The
condition of stomach has been classified as shown below into four convenient
categories depending on the quantity of food in the gut.
Degrees of feedmg
activity
1. Empty
..
Nil
..
..
2. Almost empty.. When the gut contents were less than 4 c.c.
in specimens of 30 cm. and above andwhen the gut contents were less than
2 c.c. in specimens up to 30 cm. in size..
3. Partly full

4. Full

Nil

Slack

.. When the gut contents were above 4 c.c.
and less than 8 c.c. in specimens above
30 cm. in size and when the gut contents were 2 c.c. and above and less than
4 c.c. in specimens up to 30 cm. in size..

Active.. When the gut contents were 8 c.c. andabove in specimens above 30 cm. in size
and when gut contents yere 4 c.c. andabove in specimens upto 39 cm. in size

IntenseA regular examination of the gut contents for a continuous period of
one year has shown that the feeding activity increases soon after spawning.
The mean monthly averages for a period of 12 months are shown in
Fig. 11, from which it could be seen that the feeding activity is very highfrom July to February. As the shoals of T. haumela begin to move out into
offshore waters from the month of January or February, the stragglers left
behind, mostly immature specimens measuring less than 47-48 cm., seem
to avoid bigger forms of fishes on which they feed and thereafter a totalchange is noticed in the items of food. For a period of 4-5 months, fromMarch to July, the important items of food have been observed to be composed of young ones of Acetes spp., Stolephorus spp. and Leiognathus spp.
The degree of feeding has been observed to be * slack' in individuals
ranging in length up to a size of 31 cm. (Table V); ' slack', ' active' or

156>

INDIAN JOURNAL OF FISHERIESTABLE VShowing the Sex Ratio, A verage Size of Female and Male Gonads, Degrees of Feeding Activity
and Important Items of Food in T. haumela in Different Size GroupsSizegroups(cm.)

No. of Sex ratio
specimens Female:examined
Male

Averagesize ofgonadsFemale

Male

17-19

52

1:1

2-03,

2-4

19-21
21-23

11
6

5:6
5: 1

2-2
2-65

2-6
30

23-25

20

1:1

2-9

3-37

25-27

9

4:5

3-2

3-6

27-29

62

7:5

3-56

3-9.

29-31
31-33

29
28

1: 1
4:3

3-6
3-8

3-98
4-15

33-35

67

1: 1

4-03

4-52

35-37

16

5:3

4-15

4-58

37-39

80

4:3

4-37

4-74

39-41

29

2: 1

4-57

5-07

41-43

36

2:1

5-35

5-69

3:2

5-57

5-98

43-45
45-47

74

8:7

5-64

5-98

47-49

77

3:2

6-5

7 08

Degree offeeding
activity

Important items of food

Acetes spp., Penceus spp., young onesof teleosts
Young crustaceans and teleosteans
Slack
Acetes spp., Penceus spp., young ones
Slackof Stolephorus spp.
Acetes spp., Penceus spp., young ones
Slackof teleosts
Acetes spp., young ones of StoleSlackphorus spp.
Acetes spp., Penceus spp., young
Slackteleosts
Leiognathus spp., Stolephorus spp.
Slack
Slack or Caranx spp., Therapon spp., Stolephorus spp., Acetes spp., young
Activeones of Sepia
Slack or Stolephorus spp,, Leiognathus spp.,
Penceus spp.
ActiveSlack or Stolephorus spp., remains of other
Activeyoung teleosts, Acetes spp., Penceus
spp.
Slack or Stolephorus spp., Dussumieria spp.,
Leiognathus spp., Penceus spp.
ActiveSlack or Caranx spp,, Kowala coval, Mugil
Activespp., Therapon spp., Stolephorus
spp., Penceus spp
Slack or Stolephorus spp., Dussumieria spp.,
Activeremains of other teleosts, Acetes
crsn
J^/3ti/onc cr\r\
spp., Penceus
spp
Slack or Trichiurusrichiurus spp., Dussumieria spp.,
ActiveStolephorus spp.,t^^., Leiognathus
„ •
spp.,
Acetes spp., Penceus spp..
spp. Sepia
Slack,
Trichiurus spp., Therapon spp., SciActive or cena spp.,Caranx spp., Stolephorus
spp., Acetes spp., Penceus spp.,
Intense
Silicoflagellatse
Trichiurus spp., Hemiramphus spp.,
Slack,
Active or Mugil spp., Caranx spp., Stolephorus spp.
IntenseSlackBiology of Ribbon Fish TriohiuTus hmTada (Forskdl)

157• TABLE V—(Continued)

Size
No. ofSex ratiogroups specimens Female:Male(cm.) examined

Averagesize ofgonadsFemaleMale

Degree offeeding
activity

49-51

78

5:3

6-63

7-16

51-53

77

3:2

6-74

7-35

53-55

75

2:1

7-41

7-92

55-57

31

5:3

7-2

7-63

Active orIntense

57-59

25

3:2

7-53

8-0

Active orIntense

1: 1

8-5

9-0

Active

59-61
61-63

Iffl^ortant items of foodSlack,
Trichiums spp., Sciana spp., Mugil
Active or spp., Therapon spp., Sardinella
Intensespp., Kowala coval, Caranx spp.,
Stolephorus spp., Penceus spp., Silicoflagellats
Slack,
Trichiums spp., Mugil spp., Sciana
Active or spp., Caranx spp., Leiognathus
spp., Acetes spp., Penceus spp.
IntenseSlack,
Trichiums s^., Sardinella spp., SciActive or ana spp., Caranx spp., StoleIntensel^rus^ p . , Metapenaus

remains

Trichiums spp. Sardinella spp.,
Kowala coval, remains of young
teleosts* intense' in individuals ranging from 45-1-55 cm., 'active' or 'intense'in those ranging from 55 • 1-61 cm. and only ' active' in those above 61 cm.
Comparing these with the stages of maturity, it couM be seen that in immature specimens, the degree of feeding is ' slack', and in mattmag ones
' slack', ' active' or ' intense'. Certain notable features in these observations are that T. haumela has been found to feed intensely when they attaina size of 47-48 cm. (size at maturity) and that this type of feeding activity
continues until they attain a size of 61 cm. after which the feeding activity
decreases from ' intense' to only ' active '. Thus it could be seen that thedegree of feeding activity is more or less closely associated with theattaittment of maturity.

158

INDIAN JOURNAL OF FISHERIES

j2
to

c

c
c
-t->

3

be
0)

ho

a>

>
CO < )I II I i

s

--•

£P

d

4J

i-s

<

C/3

O

Fio. 11. Average monthly gut contents for a period of twelve months.
XII.

DISCUSSION

The spawning period of T. haumela is largely a matter for inference
from circumstantial evidence though its duration is indicated to some extent
by the studies on intra-ovarian eggs and occurrence of post-larv£e. This species
undoubtedly migrates from inshore to offshore areas for spawning.
Devanesan and Chidambaram (1948) and Jacob (1949) recorded fromplankton of October 1939, eggs believed to be those of ribbon fishes but as
no details have been given by them, the eggs could not be referred to any
particular species. Chacko (1950) claims to have observed eggs and larvaof T. savala from the plankton around the Krusadai Island. As stated by
Delsman (1926) the eggs of ribbon fishes are so remarkably alike that it isdifficult to ascribe them to their respective species until their development
is followed to the stage at which specific characters can be noted. In theBiology of Ribbon Fish Trichiurus haumela {Forskdl)

159

absence of such developmental details, and as the present investigations
have shown that T.muticus and T. haumela occur, the former in larger
numbers, in the Gulf of Mannar, it is equally possible that the eggs referred
to by Chacko belong to T.muticus or T.haumela.
Tang and Wu (1936) in a preliminary note on the spawning ground ofT.japonicus (Schlegel) in Poi-hai (Gulf of Chihli) have stated that the depthof the sea where they found great quantities of the eggs of T.japonicus was
13-5 metres. This observation throws Ught on the fact that the ribbon
fishes probably do not spawn in the disturbed shallow waters. The authprs
also observed eggs of T.japonicus floating on the surface waters over an
area of more than 10 nautical miles in diameter, giving the water a pink
appearance. Delsman (1926) has only stated that the eggs of ribbon fishes
have a fairly large diameter and contain a considerably large oil globule but
no details on the exact range in size of either the eggs or the oil globules
are given. It has been found from this work that though freshly spawned
eggs of the common Madras species T. haumela have not been observed,
the average size of the largest intra-ovarian eggs from mature ovaries inStage III is 1 • 1 mm. It must be concluded therefore that the eggs.of T. haumela are definitely larger than those of T.japonicus.
Closely associated with the fact that no freshly spawned eggs of T. haumela were encountered by a large number of observers, is the absence ofrecords of its post-larvae. However, from Tang and Wu's account ofT.japonicus, it would appear that the post-larvae (which measure 57-95 mm.
a month after hatching) do not swim away from the area where the eggs
were spawned. The absence of eggs as well as larvae in the inshore areas(Nak, 1952) may be explained on the basis of the offshore spawning habitsof the fish. It is inferred that T. haumela spawns in offshore waters by June
and that the young ones of 7-8 cm. in size migrate into the coastal waters
by the end of July. It has also been observed that the migration of theyoung ones of T. haumela to the coastal waters takes place along with the
shoals of adult individuals and not independently.
Regarding the duration of spawning, there have been different
views {vide supra). For T. savala, Chacko (1950) observed that the spawningperiod extends from September to October in the Gulf of Mannar. A studyof the gonads and ova does not lend support to the views that the spawningseason is either a prolonged one or that there are two distinct spawningseasons. Observations reported earlier in this paper clearly suggest thatthe spawning is restricted to a definite and short period and that it takes
place only once a year. Such abundant occurrence of eggs of Trichiurus spp.

160

INDIAN JOURNAL OF FISHERIES

extending over an area of 10 nautical miles as reported by Tang and Wu
also suggests that the spawning takes place within a short period. If it were
to be a continuous process, there ought to have been at least a few larvae
hatched out from the first stock of eggs shed during the commencement of
the spawning period.
Venkataraman (1944), Devanesan and Chidambaram (1948), Jacqb (1949),
Prabhu (1950), Tham Ah Kow (1950) and Vijayaraghavan (1951) have dealt
with the feeding habits of ribbon fishes. The observations of all the earlier
authors show that the ribbon fishes are mainly piscivorous. Venkataramansays that coupled with the voracity for eating, these carnivorousfishesexhibita total lack of choice in their food. Devanesan and Chidambaram (1948)
say that the diet of ribbon fishes is remarkable because it consists mostlyof economically important food fishes though this wide range in fish dietdoes not include oil sardine or mackerel. However, the present observations agree with those of Tham Ah Kow in that the main items of food havebeen found to consist of white-baits and prawns.
Vijayaraghavan (1951) found in general an increased feeding activity
in T. haumela extending only from September to November, but no infoimation has been given regarding the variation in the degree of feeding in the preand post-mature size groups. It may be mentioned in this connection that
his observations were based on only 37 specimens in 10 inches size groupand 107 specimens in the 20 inches size group. All the specimens in theformer size group would have been immature and it is not clear whether there
were any mature ones at all in the specimens examined in the 20 inches sizegroup. Those observations, therefore, cannot be related to the present investigations which have shown that there is a wide range in the items of diet andthe degree of feeding among the immature, mature and spent specimens.
The immature individuals have been found to feed mainly on young prawns
and clupeids without any seasonal variation. The mature and spent specimens have been found to be voracious feeders, even resorting to cannibalism,
whereas individuals just prior to spawning show a definite slackness in feeding.
However, from the quantitative analyses made during this study it has beeninferred that the active feeding in T. haumela is evident soon after spawningin July and continues up to February.
XIII.

SUMMARY

Among the three species of the genus Trichiurus, namely, T. haumela,
T. samla and T. muticus, inhabiting the Indian waters, T. haumela has beenfound to predominate in the landings at Madras. The diistribution of theBiology of Ribbon Fish Trichiurus haumela (Forskdl)

161

three species along the east and west coasts of India and certain chief
characters by which they could be identified in the field are given.
The structure of the ovary in T. haumela and the stages of maturity
based on the condition of the gonads are described. Adult size is reachedwhen the fishes are about 47-48 cm. in length.
It is inferred from observations detailed that this species migrates tooffshore waters in Jun» probably for spavmiiig which appears to be restricted
to a definite short period. This inference is supported by the studies on the
diameters of intra-ovarian eggs from sections of spent and mature ovaries.
T. haumela appears to spawn only once a year, as post-larvae of 7-^8 cm.
in length occur by the end of July. From length frequency studies it is foundthat this species spawns first during its third year of life.
The otoliths do not show any growth rings and the calcification appears
to be continuous.
From a study of tiie size frequency distributions, it is shown that
T. hawnek attains a size of 18 cm. in the first year and 30 cm. in the second
year, TTie large fish of 54 cm. have been inferred to belong to the fourthyear class.
T. haumela is a voracious carnivore. The seasonal variations in thefeeding activity of specimens of T. haumela at different stages of maturity
are discussed.
XIV.

ACKNOWLDGEMENTS

The author is grateful to Dr. N. K. Panikkar, Chief Research Officer, Central
Marine Fisheries Research Station, Mandapam Camp, for his encouragement
throu^out the period of the present investigation and to Dr. C. P. Gnanamuthu,
Directcw, Madras University Zoology Research Laboratory, for his very helpful
criticism.
Allen, K. R.

1938

Baranov, F. 1916
Bapat, S. V. Banerji, S. K.
^nd Bal, D. V. 1952
OsrniSh, ttomas. 1867
. 1871. 1872
Qogg, Stephen. 1871
XI

XV.
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