et al. (1982). The recruitment pattern was worked out to assess the seasonality of recruitment of the

I ~

Journal of the Indian Fisheries Association 24.1994 (Proc. Nat. Symp. Aquacrops), 1~39

ESTIMATES OF GROWTH, MORTALITY, RECRUITMENT PATTERN AND MSY OF IMPORTANT RESOURCES FROM

THE MAHARASHTRA COAST

. SUSHANT K. CHAKRABORTY, VINAY D. DESHMUKH, MOHAMMAD ZAFAR KHAN, KUBER VIDYASAGAR AND SADASHIV G. RAJE, Bombay Research Centre of Central Marine Fisheries Research Institute,

Army & Navy Buildings, 148, M.G. Road, Mumbai . 400 001.

ABSTRACT

Based on the data collected from the year 1987 - 1991 the growth, mortality and recruitment pattern of eighteen species of fish, two species of cephalopods and four species of penaeid prawns have been presented in the present communication_ The total mortality coefficient, (Z) varied from lowest of 1.20 for O.cuvieri to a highest of 10.78 for P.stylifera. The natural mortality coefficient, (M) varied from 0.52 for T. thalassinus to 3.44 for S.crassicornis.

The average annual yield of eighteen species of fish, four species of prawns and two species of cephalopods are 65,083, 38,404 and 11,373 tons as against the MSYof 83,023, 72,460 and 10,475 tons respectively.

The MSY estimated for the total fish stock is 1,77,753t where as the present yield is 1,14,859t. This indicates that higher yield can be obtained by increasing the effort.

INTRODUCTION

The state of Maharashtra with a coastline of 720 km. and continental shelf of 89,096 sq.km. has rich potential for marine fisheries. The areas of potential fishing grounds in

o

^{to 50 m .:..nd} 50-200 m depths are 2.55 and 10.48 million hectares respectively (Srinath et 01., 1987). It contributes about 16% of the total marine fish landings of India. The fishing and allied activities are very well developed in the state in general and Bombay in particular. The process of mechanization of fishlng

craft began in the early sixties and continued on increasing till mid eighties. The increase in the mechanization of the fishing fleet has however, slowed down. The number of units operating now at new Ferry Wharf and Sassoon Docks centres are about 600 and 450 respectively. The description of the craft, gear and area of operation of this fishing fleet has been described by Chakraborty et al.

(1983). But the depth of operation of the commercial trawlers have increased from 40 to 70 m and the duration of fishing has also gone up from 3-4 days to 5-6 days.

2 CHAKRABORTY ET AL.

In the present communication the length frequency data collected on various fish, penaeid prawns and cephalopods were used fof growth, mortality, recruitment and estimation of maximum sustainable yield. The data cover fourteen genera of fish which includes eighteen species, two genera of cephalopods with as many species and three genera of prawns covering four species. The length frequency data of two species of perches (Epinephelus diacanthus and Priacanthus hamrur) and one species of sciaenid (Pennahia .macrophtha- Imus) have been collected from Sassoon Docks as these three species are not represented in adequate quantities at New Ferr! ·~harf.

Though, Harpodon neher/ius and. Coilia dussumieri are landed in appreciable quantity by trawlers, the major gear for these resources is IIdol"

net which is operated mainly in the inshore waters. Therefore, the length frequency data for these two species were collected from Satpati, one of the major "dal^ll net centre in Maharashtra. For rest of the species the data were collected from New Ferry Wharf.

The growth and mortality parameters form the basis in the stock assessment and formulating the management strategy of the resources. Although, information on these parameters of some of the species are available from Bombay waters, they are few and scattered.

This is an attempt to bring out as much information in one place for

better understanding of multi species fishery in the region.

MATERIAL AND METHODS Weekly length frequencies on various species were collected at the landing centres. In the present communication data collected for the years 1987-1991 have been used. The length frequencies were grouped in different length classes depending on the largest size recorded and this was raised for the day and subsequently for the month using the method of Sekharan (1962). The von Berta- lanff'y's (1938) growth parameters, the asymptotic length (L~) and growth cofficient (K) were estimated using ELEFAN programme developed by Gayanilo et al. (1988). The von Bertalanffy's equation is as follows.

Lt = L~ _ (l_e-^K(t-to)j

This programme does not produce an estimate of to'

The total mortality coefficient (Z) has been estimated by length- converted catch curve method of Pauly (1982) and the natural mortality coefficient was estimated mainly by Pauly's (1980) emperical formula which is as follows.

Log M = -0.0066+0.279*Log Loo + 0.6543 Log K+0.4634* Log T

where Loa is in em and temperature is in degree centigrade.

The mean environmental tempera- ture of 27 .2°e was taken from Bapat

GROWTH, MORTALITY, RECRUITMENT AND MSY OF RESOURCES 3

et al. (1982). The recruitment pattern was worked out to assess the seasonality of recruitment of the

stock investigated.

Fishing mortality coefficient 'F' was computed by subtracting (M) from (Z) and the exploitation ratio was derived from the relation.

E = F/Z

The maximum sustainable yield (MSy) was estimated by Corten's ( 1974) formula and the calculations were done on a PC using ELEF AN II programme .

The summary of various parameters on growth, mortality and recruitment pattern obtained for all the species are given in Table 1 and the estimates of MSY, standing stock and annual and average yield for 1987-1991 period in Table 2.

RESULTS AND DISCUSSION

The total mortality coefficient (Z) varied from lowest of 1.20 for O.cuvieri (Fig.3) to the highest of 5.0 for O.militaris (Fig.17 ) amongst fish, 2.09 to 3.0 for S.acul ea ta and L.duvaucelii (Figs.20 & 21 ) amongst cephalopods and 3.82 for M.

monoceros (female) (Fig .24) to 10.78 for P.stylifera (Male) (Fig .2 3) among prawns . The natural mortality coefficent (M ) ranged from 0.52 (A.t halassinus) (Fig.16) to 3.44

(S .crassicornis) female ) (Fig.28).

Out of eighteen species of fish

stocks studied, eleven are optimaly exploited and seven are under- exploited (Figs. 1-19) The penaeid prawns appeared to be under - exp loited where as cephalopods are optimally exploited (Figs. 20-29).

Fourteen species of fish analysed show recruitment in two pulses while a couple of species indicated recruitment in single pulse while r est of the two species it could not be resolved (Figs . I-18). Both the species of cephalopods indicated recruitment in two pulses. Among the pena ei d prawns' P.stylifera showed recruit- ment in one pulse and M . monoceros shows recruitment in two pulses. The recruitment pattern cou ld not be resolved for M. affinis and S.crassicornis femal e shows recruit-

ment in two pulses and male in one pulse. (Fig. 28 & 29).

Th e gear used is shrimp trawl and th e effo rt is mainly directed towards catching of prawns. But in the last four to five years cephalopods have also gained economic importance. Because of this, a part of the effort is also directed towards catching of cephalopod resourc es . Recently, rihbonfish, hecause of its newly acquired export value, is also caught in good quantity.

It is to be not ed that all the

. species of fish and cephalopods are

landed as by-catch of the shrimp

trawl. The occurence of by-catch

raises a number of biological,

economical and social questions. It

4 CHAKRABORTY ET AL.

Table 1 Growth and mortality parameters of the species studied

Name ^L~ K Z M F E

Scoliodon laticaudus 726 0.48 3.00 0.90 2.10 0.70 (female)

Seoliodon wticaudus 740 0.63 3.00 0.90 2.10 0.70 (male)

Otolithes cuvieri 398 0.52 l.20 0.86 0.34 0.28 Johnieops vogleri 345 0.72 3.20 l.10 2.10 0.65 Johnius macrorhynus 350 0.75 4.10 l.20 2.90 0.70 Johnieops sina 240 0.80 6.56 l.60 4.96 0.75 Pennahia macrophthalamus 245 0.64 2.00 l.30 0.70 0.35

. Nemipterus japonicus 335 0.65 2.80 l.10 l.70 0.60

Nemipterus n:-esoprion 286 0.71 3.44 1.40 2.04 0.65 Epinephelus diaeanthus 502 0.61 l.50 l.12 0.40 0.26 Priacanthus ^ha1J1,TUT 345.5 0.66 . 2.50 l.10 1.40 0.56 Saurida tumbil 600 0.51 2.80 l.00 l.80 0.64 Saurida undosquamis 421 0.51 2.52 l.10 l.42 0.56 Harpodon nehereus 413 0.73 3.10 l.53 l.57 0.51

Tachysurus caelattts 521 0.68 3.50 l.10 2.40 0.68

Tachysurus thalassinus 850 0.28 l.50 0.52 0.97 0.65 Osteogeneiosus militaris 600 0.65 5.00 l.10 3.90 0.78 CoUia dussumieri 230 l.20 7.05 3.00 4.00 0.57 Trichiurus lepturus' . 1480 0.40 2.62 0.75 l.87 0.71 Loligo duvaucelii 343 0.49 2.09 l.10 0.99 0.47 Sepia aeuleata 297 0.56 3.40 l.10 2.30 0.67 Parapenaeopsis stylifera . 140.8 2.15 7.60 3.60 4.00 0.53

(female)

Parapenaeopsis stylifera 119.2 l.45 10.78 2.96 7.82 0.73 (male)

Metapenaeus monoceros 219.2 1.40 3.82 2.40 l.42 0.37 (female)

Metapenaeus monoceros 180.5 l.35 4.50 2.50 2.00 0.44 (male)

Metapenaeus affinis 188.8 l.47 6.78 2.58 4.20 0.62

(female)

Metapenaeus affinis 15l.5 l.50 4.60 2.78 l.12 0.40

(male)

Solenocera crassicornis 139 2.00 10.36 3.44 6.92 0.67 (female)

Solenoce.ra crassicornis 92 l.50 6.00 3.20 3.60 0.53 (male)

Lao is in mm and K is annual

GROWTH, MORTALITY, RECRUITMENT AND MSY OF RESOURCES 5

Table 2 : Yield and stock parameters of fish, cee.halopodsand prawns

Name Yield ^LcIL~ MlK E Emax F Y/F MSY

Scoliodon laticaudus 2349 0.77 1.87 0.70 1.0 2.10 ll19 3356 (female)

Scoliodon 1aticaudus. 2150 0.46 1.42 .0.70 0.66 2.10 1024 2024 (male)

Otolithes c"uvieri 6063 0.40 1.65 0.28 0.61 0.34 17832 13209 Johnieops v,lgleri 6126 0.40 1.52 0:65. 0.67 2.10 2917 6314 Johnius macrorhynus 4958 0.45 1.60 0.70 0.66 2.90 1709 4674 Johl1:ieops sina 2118 0.60 2.00 0.75 1.00 4.96 427 2824 P.ennahia macrophthalamus 1038 0.44 2.03 0.35 0.70 0.70 1483 2076 Nemipterus japonicus 1242 0.48 1.69 . 0.60 0,71 1.70 731 1470 Nemipterus mesoprion 962 0.49 1.97 0.65 0.75 2.04 472 ll10 Epinephelus diacanthus 280 0.46 1.83 0.26 0.71 0.40 701 761 Priacanthus hamrur 283 0.56 1.66 0.56 0.83 1.40 202 606 Saurida tumbil 3193 0.43 1.97 0.64 0.68 1.80 1774 3388 Saurida undosquamis 171 OA7 2.15 0.56 0.77 1.42 120 236 Harpodon nehereus 37270 OAO 2.09 0.51 0.65 1.57 23739 47650

Tachysurus cae latus 453 0.71 1.61 0.68 1.00 2.40 189 666

Tachysurus thalassinus 1990 0.28 2.16 0.65 0.52 0.97 2051 1588 Osteogeneiosus militaris 2948 0.53 1.69 0.78 0.79 3.90 2268 3004 Coilia dussumieri 4793 0.64 2.22 0.57 1.00 4.00 2397 8715 Trichiurus leplurus 23965 0.44 1.87 0.71 0.68 1.87· 12815 22986 Loligo duvaucelii 6125 0.29 2.26 OA7 0.53 0.99 6187 6895 Sepia aculeata 5248 0.30 1.96 0.67 0.53 2.30 2281 4143 Parapenaeopsis stylifera 12320 0.64 1.67 0.53 1.00 4.00 3080 23245

(female)

Parapenaeopsis stylifera 5646 0.72 2.04 0.73 1.00 7.82 722 7734 (male)

Metapenaeus monoceros 4563 0.59 1.71 0.37 1.00 1.42 3213 12332 (female)

Metap~naei!-s, monoceros 1709 0.61 1.85 0.44 0.91 '2.00 855 3519

,

^(male)

Metapenaeus affinis 6227 0.72 1.75 0.62 1.00 4,20 1483 10044 (female)

Metapenaeus affinis 2876 0.79 1.85 0.40 1.00 1.12 1580 7190 (male)

Solenocera crassicornis 4401 0.68 1.72 0.67 1.00 6.92 636 6569 (femule)

Solenoce·ra crassicornis· 662 0.71 2.13 0.53 1.00 3.60 184 1249 (male)

Lc

=

Length at first capture, Emax ::::: -Maximum exploitation rate, Y IF

=

Standing stock.

6 CHAKRABORTY ET AL.

is noteworthy that though by-catch forms quantitatively a large consti- tuent, economically it does not fetch good value. But though not very remunerative, their value is not altogether negligible. The value of minor species can make all the differences between a profitable and nonprofitable trip (Gulland, 1983).

The groupwise distribution of catch shows that fish forms 56.77%, prawns 33.4% and cephalopods 9.9%.

Out of eighteen species of fish stocks studied eleven are optimally exploited whereas seven species are underexploited. The notable under- exploited resources are O. cuvieri, P. macrophthalamus, E. diacanthus, P. ham'rur, S. laticaudus (female), C.dussumieri and T.caelatus. Both the species of cephalopods appear to be optimally exploited. The four species of prawns which together constitute 76.3% of the penaeid prawns in Maharashtra appear to be underexploited.

The standing stocks of eighteen species of fish is 78,420 t, of two species of cephalopods is 8,468t and four species of prawns is 1l,753t.

The present average yield of eighteen species of fish is 65,082t whereas the MSY is 83,023t thus ,giving scope of increasing the catch by 27.57%. Th", present yield of four species of prawns is 38,404t whereas the MSY is 72,460t giving a scope for increasing the catch by 88.67%.

The present average yield of cephalopod is 1l,373t and the MSY

is estimated at 10,475t. The estimated MSY of total fish stock is 1,77,785t whereas the present yield is 1,14,859t. Therefore, there is a scope to increase the total fish catch by 54.78%.

The "dol' net is an important gear operated in the northern part of Maharashtra. Bombay duck Harpodon nehereus is the target species of "dol" net and Coilia dussumieri is one of the by-catch.

The average yield of the former species was 37,270t whereas the MSY was 47,650t. C.dussumieri the average yield was 4,793t whereas the MSY was 8,715t. This species appears to be under exploited.

Bombay duck shows a wide year to year fluctuation in the catches (Table 2) with 18,565t in 1991 to 25,222t in 1989 and 48,000t in 1990. Srinath et al. (1987) observed that catches by the dolnetters did not respond positively to the effort expended and any change in the effort may not have any impact on the landings. ' Khan (1989) also observed that the dol net fishery is labour intesive, the effort is regulated depending on the catch per haul. Due to economic reasons the fishing is suspended when the CPUE is very low.

Gulland (1975) suggested that if the 'E' value is more than 0.5, the stock understudy appears to be overexploited. In the present study we find that in most of the species of fish, prawns and cephalopods the 'E' is more than 0.5. In spite of that these species do not show any sign

GROWTH, MORTALITY, RECRUITMENT AND MSY OF RESOURCES 7

of overexploitation like drastic decline in catch and catch rate,

It can thus be stated that perhaps the concept of Eopt of 0,5 may not hold true in the tropiGs, It is also observed that all the species studied have in general a small standing stock and the LclL= ratio is also very ,high, It is noteworthy that a small standing stock is able to generated a higher yield in the north west coast of India (Table 2), The chief reasons may be attributed to

a, Faster rate of growth, b, Abundance of food supply,

c, Less abundance of predators like

"Ghal", IIKoth^ll, "Dara" and

"Karkara" and

d, Majority of species have protracted spawning which results in recruitment through out the year, Jones and Banerji (1973) estimated that the potential yield of Maharashtra waters as 2,62 lakh tonnes, George ef al. (1978) estimated the potential yield of north west coast off India as 8,43 lakh tonnes based on the rate of production, Antony Raja (1974) gave an estimate of 3.53 lakh tonnes in which 2.7 lakh tonnes obtainable from the 0-50m depth zone. Kalawar (1978) and Srinath et al. (1987) arrived at potential yield of 3,74 lakh tonnes, They also observed that the relationship between catch and efforts by trawlers was C ~

O,65lfLoo4(?~O,9) and suggested that

additional 60,000 tonnes of trawl catch are expected by increasing 40%

of efforts at 1984 leveL It was further suggested that the increase could be made in a phased manner. There were 1792 trawlers in operation in Maharashtra in1984 since then the numbers of tawlers have increased to 2118 in 1992-1993, Despite this increase in the number of trawlers in Maharashtra in the last eight years there is no decline in the total fish landings,

The present LclL= for all the species taken together is 0,53 and the estimated exploitation ratio is 0,53 whereas using the relative yield per recruit model (Fig, 30) the estimated E max is 0,83 at which the projected yield (MSY) would be 1,77,785t. The present avrage yield is 1,14,859 (combined catch of all the species), The study indicates that at present none of the species studied is over exploited, Most of them are either optimally exploited or underexploited, The study thus indicates that the present fishing fleet could be safely be increased to 25% without having any adverse effect in the fishery,

. This document would be useful to fishery biologists and management people in fishery and related industries as it covers the age,

growth~ mortality, recruitment I1.tttern and MSY of most of the co ltime,rci all y important fish, cephil-lopods and prawns.

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15 u

'"

a:

.,.

7·5 REL.ATIVE AGE (YEARS-t.)

... . '" ... ..

III ~ ~

• - ... R

j b-•

I;! I • • • a ... ~ h ~

420 oS 3.0 :I: % ~

-

% 2~O I- 180 III

ei

120

...

60 b H ----I-YEAR--- Fig. 10 : Epinephelus diacanthus L==502mm, K=O.61, Z=l.S. Recruitment in two pulses.

~

0 :<i >-l .::I:

s:

0

;:j ~

~

.~ "

t<J n

~

~ >-l

s:

t<J

~ ~

tl

s:

UJ ..: 0 ."

"

t<J UJ 0

" "

n t<J UJ

.... ...,

0- N

..

6

•

c II:

i ! £ i ~ •

~ -

r

.J

• p -p ~ ~'

~

V

~

--

'"

00

~ ~ ~ ~

N

...I

f' •

• P -

~

. p ~

j .

p --

^F0-

P

,00 Z 240 2 z 110 %

...

120 ~ w 60 -' Fig. 11 : Priacanthus hamrur L==345mm, K=O.66, Z=2.5. Recruitment occured in two pulses.

~ 00

13~

J

q

,

z

•

'" 2

<D (\J r;> o

"

<:: a: .0 • 0 •

• 0

Q) en

'" p

,... '<T <D ,...

'" '" po ~\

:::J

III

J f M

0· -. .

•

t

15

"'

OJ N

'" rr

~

...

r-' ~ ]I

oI! • ~

J

P • ~

'"

N , :>

'" "'

^{<t ::;J}

_• ~ .. ~ : ~

~-

--

M , A J A MONTHS

2°1

¹⁵

i 1

:>

5

10

Ii!

~ • 5

•

"' '"

00 OJ

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o ~ ..

,

• 01

~ ~ ~ '1 " ~~ :, I---'

0

50 40 ::E u z 30 - :x:

,.,

20 ~ w 10 ...J .... 2 3 4 ---------rYEA~R-------------- RELATIVE AGE (YEARS-to) Fig. 12 Sallrida tumbil Loo;600mm, K;O.51, Z;2.80. Recruitment in single pul .. e.

"

OJ 0 ~ >-l .:I: :;: 0

::J ~

~

. ::1 t:l

() OJ

c:

~ >-l :;: to Z >-l

~

t:I :;: rn ><: 0 "l OJ t'l rn 0

c:

OJ () to rn

"' "'

Fig. 13

...,

'"

OJ o e a: 10

d

8' 2

" ~

~

o m .. '" OJ i,J ~

I p • •

q 0 " .!:I j

8 II ~

~ ::J

1'-)

"'

:!l ~

p • b !'J

• "' '"

'" '"

^-

~

:l ~ ~ :..---

J r M

•

M J J

-

s MONT HS 20

...

I!>

... ~

z

"'

~ t. 10 ~

"'

u w II: 5 ~ • 2

, •

5 6 RELATIVE AGE (YEARS-'.)

~

'" ..

^d. -J

"" -

³⁶⁰

~ ~ 240 ! ~

"

z 120

"'

-' I-YEAR· SaUl-ida undosquamis L==412mm, K=O.51, Z=2.52. Recruitment pattern could not be resolved.

'"

0

~

:>;l ~ o

~

l'l 'l

~

<i '- z

•

~ o

111

(\j CD

o

L

" a:

9~ •• "

" •

e'" ,

•

'"

!D <r J

o ...

'" '" '"

~ M 2

'<t

'"

10 A

•

'"

If)

...

M

o

J RELATIVE AOE(YEARS-Io)

20 t- Z I~

'"

~ l- S '" 10 u

'"

0: f. 15

o 10

'" s

o

'" o

o

N

~

N

o

300 300 :I 240 2: 180 120 60

z: % l-

i ....

..J 1-YE AR --- Fig. 14 Harpodon nehereus L==413mm, K=O.73, Z=3.l. Recruitment in two distinct pulses.

.1 5 ~ ~~ [;l

o

13 ~

r.J Z >-3

~

to

~

><: o "l

[;l

en

o §l

o r.J en

'"

~

Fig. 15

<"

,

z

• ...

o ..J

~ >-n N N i;j

.

~- ~

:l •

i' b

.. "'

. --, ~

'"

~ $ >-N ~

:g &

I: p

... •

⁸⁰ 20

~ -:: a -

^~

. ~ . ~ S-:;

~ 'p •

p p

~60 !l

"

300 T.

• •

o

·

e

..

J F

.. •

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p

I' • -

. ;

.. J J MONT HS 17

... - .. ~ .... ....

••

.- . . •

• • 7 ~I ~.----~,~.----_.r'----~'----~I-- 2 .!. '" RELA"f'V£ AGE ( YEARS-I. )

20

~ ~

20\0 X

..

190 ~

...

~ ~

---

~

120 ..J 60 A s o _________ IY[A,RR~ ____________ __ Trachysurus caelatus

L ~ ~

521mm, K = 0.68, Z = 3.5. Recruitment in two pulses.

" "

Q

~ ~ o ~

to '-l 1=:

16 t4

< ,

~ 12 ~ J/ '0 B

I

;;;

'"

6

.

c

'"

III

., :

~

It'

., •

...

o

..

b

.. ., ., "' . .. .. '" .,

l ~ ~ ~

: ~

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(II

.,

~ ~

..

N

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:J

-

~ b ~

.. ... .. ,. •

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~- J r ... A .... J MONT HS

... .-

'.~

..

• 2 3 • 5 6 R£ LATlvE M:iE CY[ARSo,o)

J A 5 o N o ~o ,.2Z

'" ...

:J: t- ~ .5

... ..

~ 7·5 ---'-YEAR

60

a

! 40 x l- i

'"

20

...

Fig.16 Trachysurus thalassinus L~

=

850mm, K

=

0.24, Z

=

1.5. Recruitment in two distinct pulses.

"

:<l 0

~ :r: s:

0 ::0

~

~

-~ gj

() :<l

c:

~ >-3

s:

t>j Z >-3 ;.. Z tl

s: '"

0< 0 "J

gj '"

0

c: fl

t>j

'" '"

co

~ z

- •

8'

~ 6 • '" cr

19 II 3

.... ~

J f

N

.,

M

10 [)j

§

.\ M

/~~

o

•

2 3

II) 10 J

•

RELATIVE AGf (YEARS-to

o OIl

..,

J

., :!:

A

ro

1-15

z ...

~

t:

~IO u UJ a: ;1. 5

s

C1>

..

N ()

~

N

'" ....

t-

o

50

o

30 20 10

z z !

:I: to z

"

.,J

'"

--1-YEAR...:....-.,..--___ _ Fig. 17 Osteogeneiosus militarias L~ = 600mm, K = 0.65, Z

=

5.0. Recruitment in two pUlses.

'" ,.. I

tJl o

~

t'l

.., ~

N

.. o •

Ie a:

ClIO N

.,

J

- -

4 "- Z

• ...

¹⁴

• • ... .,

II ID

1ft

., ... r M A

•

N

...

M J J A. N ON T~S

on N It) 5

II>

'" .. o

10 co N

o GI

o

:s:

':I! 180 z 120%, ~

"

z 60 ...

...

o -' 12

.... -...

Fig. 18

•

8

• •

RELATIVE AGE (YEARS_! \ o Coilia dussumieri L~

=

230mm, K

=

1.2, Z

=

3.6. Recruitment pattern of this species could not be resal ued.

~ ~

:<: o

~ ~~ [;J

(")

~ ~

t'l Z >-l

~

tl :<: rn >< o "1

[;J

rn o

~

t'l rn

'"

en

C'

-

-

a '" .. ;f;

~ N

~ -

Rn·.0252 I--

,

;:I ~

R

I;>

J ... .I ~ 13' P • • Fl r--

J f '" A '" J J A

~ ,..

10 j I

~,

C

I •

•

II>

.... P

N

o N

'" "' •

I .

-

lio

:l 100 u z 80

-

l: '~. 60 f- III 40 Z

'"

..J 20

r;

MONTHS 20 13

•

f-I~ z UJ :E

...

~ 10

Irl '" ,.

~

" 9j ... ~ ~ ... -.

} 5

,,' . •

:3 4 ----I-YEAR---- RELATIVE AGE ( 'I'[ARS-Io ) Fig. 19 Trichiurus lepturus L~

=

1480mm, K

=

0.4, Z

=

2.62, Recruitment occured in two pulses.

'" '"

() :0: :» ~

!;2

OJ 0 :0 >-3 ><: I.>] 'l :>- ~

240F. E

~ J 1 ) g r }.{ ~ j~ too i ~ _ iii. ' ..i.l ~

120

~

0 J of M A M J J A S 0 N D MONTHS

; '~1

30·0

" , , ,

0 22·5 N

7i

, - .

c:

,

0 •

.,

a.

" "

J E ~

'"

.c

:j "

"

15,0 ~

"

~ 0

z

v a:

..

c: -' S!

•

7·5

•

0

--,-

2 3 0 R elalive age ~---One year Fig. 20 Loligo duvaucelii. L~ ~ 343mm, K ~ 0.49, Z ~ 2.09. Recruitment occured in two pulses.

,. G)

~ ~

_;J: ~ o

~ ~~ [;l

(') ~

~

Z >-3

§

~ en -< o "l ~ t>l en o

c:

~ (') t>l en

'"

-.J

• - •

I (); ~t;J

• •

$I

• .,

I

•

o I " " co

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J F M :::: 13- •

<J

" J~\

X I.

~ ~ Q~

•

..~~ ~ -I. ".~ ~ 71 "~ • ~ j.

<, ••• ..J 5 • ~--:r:-i--3 .

--r-;;:s

I i:3., f) 2 lelotive o',le

::J •

• P

3

~

A

- b • , \, .

^:i

-II

I

~ ~ II

J ~ I

I

I

~

~ ~ t-' ~

~

p iii

p

i? - •

t'"'

..

~

~ .~

L

E

E .5 .r:.

-

co c

'"

..J M J J I>. 5 J N 0 Months 3(}Q'

I I g

225"

.~ I ~

u 15') ~ cr ~

•

T5

o I ,=-:::: . ./ ---- b

----One yeor ---1 Fig, 21 Sepia aculeata, L~ = 297mm, K = 0.56, Z = 3.4. Recruitment in two pulses.

N

'"

0 :I:

»

:>;

~

OJ 0 :<1

..,

>< t>l "l )-

,.,

11'1

~

~ 0

• PJ

~

'" ~ ... :lI

N ~

.. .. :I:

0

... '" .., -

11'1 on I/) on

.,

140

:.

120 :IE Q ~ ICO

!

0

:;;

,110 %

., ., f I r r if r J{1rl:~

p: 0 s::

0

-

~ c a: 20

~ -

J F M A M J J A 5 0 N 0

.:1

~ MONTHS OJ (') ~ C 20

::J

~ 17f t1l

z

t-

.,

~f

'"

I~

»

:IE Z t-tl

-

111

,- j "

::> ~

,

a: 10 til

, •

u

-<

-II

,

0 vi'

'"

." .!!

,

a: 9

, .,.

!)

i:l

en 0

,

C 7 ~

, ,

~ (') 0 t1l en RELATIVE AGE -I. I YEAR Fig, 22 : Parapeneopsis stylifera (Female) L= ; 140,8mm, K; 2,15,

'" '"

Z = 7.6. Recruitlnent occured in two pulses.

~

0

... .,

;;;

,.. ...

~

:::

N N ~

!!! ...

!I! 0

'"

II) 1'1 on ~

'"

~

.. .., ..

W 0 100 :Ii :J! 80 z

r

0

- '"

60 X N

...

0

"

• 40 z c

.. ...

~O -' J F M A 1\4 J J A S 0 N 0 MONTHS 0 :0::

~ ~

t;d

..

0 z 20

"

w >-J

:1

:J! ><:

..

l'l :>

~

'"l 0: I~

,.

u w

"

14

'" j

12

....

~ ~ 10

- .

• : 10

• •

... 6

, 61 •

~ RELATIVE AGE -I. 1-YE AR Fig. 23 : Parapeneopsis stylifem (Male) L=

=

l19.2mm, K

=

1.45, 7:= In,7R. Rr>f'rll;fI11r>nf nr'rur,.,r/ ;'1 hun Jlfll.~r.~

14 12

~

--10

...

.! 8 8

• • •

~

.. o

• c a:

!

J

.

J:

.. i

f M RELATIVE AGE-'.

~

...

A

$ • i

M J 300

Ii

,,~

....

~

5

I~

...

II:

.,.

T·!!

..

iii J

s· •

A

..

N ID

s

.. ...

ID o 1-YEAR

~ ,.

Fig. 24 Metapenaeus monoceros (Female) L~ = 219.2mm, K = 1.4, Z = 3.82. Recruitment in two pulses.

a

ID

o

210 180

I~I

120 ! 902:

sol ...

30 ....

.1 .: o .~ ~

(")

~ ~

> Z tl

~ o

"l

[;l

tIl

o ~ bl

co ~

~

:; .. .

~ w

~ ! ~

~

'" .. ..,

~

'" '" " .. .. .. .. .. '" .. '" .,

I l L l l

1 I

160' 140 •

! M" , 1 ~ ~ JJ-t1 to ·

IOO~

,.

'0 ~

• eo .i • ..

40

..

j 20 I I I I J ~ , . II

....

. II . ~ . J

••

. 5 0 N 0 MONTHS (') 300

~

to 0 14 ~

f\

~

.. -<

;~ t'l r2~

.., .. ~ •

:I

"

10

•

~ e-o

- • "

~

• •

z

.. -;. .

T·!!

• • -

4 .-;.;

•

• 2 0 IIlLATiVE AOI-t. I y[A~ Fig. 25 jl,;Ietapenaeus monoceros (Male) L=

=

180.5mm, K

=

1.35, Z

=

4.5. Recruitment in one pulse.

16 104 -12

., '"l

10

-. • • ..

6 4 Z

o

•

N

o

I

:

t! • ., ... ,

I I

I'

I

e

~

., It

<II

~

J F II A

•

2

M

..

z

...

2

..

5

i

I-

, s • .,

J J J

zo

j:

•

A

.. .,

on

s

.. '" " o • .. ....

N

S

ID

o

110 110 110

j

110 i! 00 %

'0 ..

80

~

040 ..I 20 RELA liVE AGE -10 ---1· YEAR---___ Fig. 26 Metapenaeus affinis (Female) L=

=

188.8mm, K

=

1.47, Z = 6.78. Recruitment pattern could not be resolved

.1

;;::

o ~ ~~ [;l

(')

~

~

~ §

;;:: ~

o

"J

[;l

rn o c::

~ fh '" '"

15 13 ~ Z

': t -.

~ 0 7 ~ Fig. 27

12

N ~

.,

0

., ... '"

0 ..,.

'" "'

on

.., .,

OJ

.,

N

'" '"

N ;;; on

.., ., ., '" .... t l h h l L l l

140 120

'" p)

N

fOO

N 6 00 , 60 ~ 40 20

J

J F

..

A M J J A S 0 N 0 MONTHS 20 >-I~ Z \oJ :i

"

".

... "

'5 10 a:

.'

V OJ , a: ~

, " •

2 R E LA TillE AGE -I. 1-YEAR M"etapenaeus affinis (Male) L~

=

151.55mm, K

=

1.5, Z

=

4.6. Recruitment pattern could' not be resolved.

'" .. !

o

~ ~ ~

l~ 13 ~

1"

• ! o •

c

""

~

J

••••• " , ';raJ. '

.2

-r • ,

~

Il $I

OJ) on f M o I ~ OJ) II RELATIVE AGE (YEARS-'.)

*

on hi

• • •

~

•

J J MON·THS 20

i

I!I ~ >- ~ 10

:.l

cz: ~ ~

~ N A

...

N on

s

'" ... ... g ... o

N ,-YEAR

en

...

I'-

o

Fig. 28 Solenocera crassicornts (Female) L~

=

139mm, K

=

2.0, Z = 10.36. Recruitment occured in two distinct pulses.

120 '00 SO

I

110 l!: % 40 ... <> z 20 ...

.

-'

C'l 1:5

:a ~ ;;::

o

I

~ l'l o

~ ::J a::

l'l

~ ~

tl

a::

Ul ..:

o

"'J

Gl

Ul o

c: f:

l'l Ul co en

'" '"

r-

'" z "

-4

1 ~ 1 f r r ~ f ~ i

MONTHS 0 ~

I~~

30 I-

~ f'l

0

ffi

2C~ 0

•

:I 0

t::

0 z9

:l

~

~ ~

a: I~

•

0 l;l

><

'"

j 7·

I>J a::

"l i-

). 7'~

~

o

MEAN RELATIVE AGl(YEARS-to I ---ONE yEAA--- Fig. 29 Solenocera crassicorms (Male)

L~

: 92mm. K : 1.5. Z : 6.B. Recruitlnent occured in one pulse.