V.N. Pillai and N.G. Menon

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Marine

Research and Management

Editors

V.N. Pillai and N.G. Menon

Central Marine Fisheries Research Institute

(Indian Council of Agricultural Research) Tatapuram P.O., Cochin-682 014

Kerala, India

2000

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27 Tuna fisheries of India

p.p. Pillai and N.G.K. Pillai

ABSTRACT

Tunas constitute 3.7% of the total commercial pelagic Jin fish production of the country (Av. 1992-96: 1,14.1067 t). The domi- nant species which support tuna fishery in the small scale sector in India are Euthynnus afflnls. Auxis thazard, A. rochel, Thunnus tonggol, Katsuwonus pelamis, Thunnus albacares and Sarda orlentalls. Of the total tuna catch (Av. 1992-96: 41,978 t). 77.6%

has been landed from, the west coast, 16.8% from the east coast 5%

from the Lakshadwei^p and 0.5% from the Andaman & Nicobar is- lands. The status of production of different tuna species in India and their environmental preference are summarised. Biological fea- tures such as food and feeding habits, age and growth, size at first maturity, spawning and fecundity are briefly discussed. Trends in the production of tunas along the mainland coast of India and Lakshadweep, population parameters and the results of stock as- sessment are presented briefly. Suggestions for future research and options for tuna fishery development in India are also discussed.

The present communication is a review of the works done during the past fifty years and discusses the present status and future strat- egy of tuna fisheries research and development in India.

Introduction

The tuna fisheries in India is limited to the small scale sector with neg- ligible inputs from the industrial sector. The results obtained till date from the exploratory surveys carried out by the Govt, of India vessels beyond the traditional fishing grounds, the industrial longllne operations of foreign fishing fleets In the Indian EEZ, the rapidly increasing rate of exploitation of

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Marine Fisheries Research and Management

skipjack and yellowfin t u n a s in the traditional sectors of Maldives and Sri Lanka and the fast pace of growth and expansion of t u n a p u r s e s e i n e fishery of France, Spain, P a n a m a and Ivory coasts in the tropical western Indian Ocean area - all these have indicated the resource availability and rich t u n a fishing g r o u n d s in the Indian EEZ and contiguous high s e a s . Despite the fact t h a t there h a s been a remarkable increase in the landings of coastal t u n a s during the last two decades, their stocks remain to be one of the least exploited pelagic fin fish r e s o u r c e s from the Indian EEZ.

For more t h a n two decades, the Central Marine Fisheries Research Institute h a s taken efforts to collate and disseminate the fishery-dependent a n d fishery-independent factors connected with t u n a fishery, a n d urged on several occasions Immediate action , on the part of the government and the i n d u s t r y to modernise and expand the small scale sector and v e n t u r e into high sea t u n a fishery. Despite Its being one of the t h r u s t a r e a s of develop- m e n t of marine fishery in the Indian EEZ, t h e m o m e n t u m it received was very low and a s a result the valuable and rich r e s o u r c e s of skipjack and yellowfin t u n a s in our waters remain u n t a p p e d commercially.

It is in this context a n a t t e m p t h a s been m a d e to highlight the p r e s e n t s t a t u s a n d future potential of the t u n a resources in the Indian EEZ. Informa- tion p r e s e n t e d in this account will help the a d m i n i s t r a t o r s in deciding on the technological options and m a n a g e m e n t t h r u s t s .

Material and methods

The d a t a b a s e on the p r e s e n t s t a t u s of exploitation of t u n a s is the information available with the National Marine Living Resources Data Centre, C.M.F.R.I., Cochin. S t a n d a r d m e t h o d s are used In the study of the biology a n d population dynamics of t u n a s (Silas et. al, 1986; J a m e s et.al.,1992). Pub- lished works of several a u t h o r s on the biology a n d population p a r a m e t e r s of t u n a s are made u s e of in the study. A bibliography on t u n a fisheries in the Indian seas h a s been recently compiled by J o h n and Bhargava (1992).

Species composition

The species of t u n a s occurring in the Indian EEZ and their common size range (cm) are presented in Table 1. The coastal fishery comprises of Euthynnus affinis, Auxis thazard, A. rochei, Thunnus tonggol a n d Sarda orientalis in the order of their a b u n d a n c e . They are taken by the drift gillnets.

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p u r s e s e i n e s , hooks a n d lines, a n d troll lines. The oceanic species a r e Thunnus albacares. T. obesus, K. pelamis and T. alalunga, which are chiefly fished by longlines operating in the deeper w a t e r s . K. pelamis a n d young ones of T.

albacares are t a k e n by pole a n d line and troll line gears in the Lakshadweep a r e a .

Tunas e n v i r o n m e n t

The temperature range for distribution, preferred temperature and h a b i t a t relative sizes of t u n a s are reproduced in Table 2 (Silas a n d Pillai, 1992). Most of the species of t u n a s respond instantly to the decrease in t e m p e r a t u r e . Cer- tain u p p e r and lower limiting t e m p e r a t u r e s determine the range of distribution of t u n a s in the ocean. Even though larger t u n a s have thermoregulatory capabilities, smaller t u n a s have limited capacity for thermoregulation. Tem- p e r a t u r e a n d forage have a major effect in critical s i t u a t i o n s a n d dissolved oxygen a n d illumination influence their distribution. Chemical n u t r i e n t s a n d p l a n k t o n biota influence their distribution t h r o u g h the forage o r g a n i s m s . The oceanic features, which play a major role in the distribution a n d migration of t u n a s are the oceanic currents, convergence and divergence, fronts, upwelling, thermocline topography and t e m p e r a t u r e gradients in the thermocline a n d position of i s l a n d s , b a n k s and land m a s s e s .

Table 1. Species of t u n a s in the Indian EEZ SI.

No.

1 2 3 4 5 6 7

Scientific Name Thunnus albacares T. obesus

T. alalunga T. tonggol

Katsuwonus pelamis Auxis thazard

A. rochet

Popular Name Yellowfin Bigeye Albacore Longtail

t u n a Skipjack Frigate t u n a Bullet t u n a

-C" Ah'7~^

Common size range (cm)

5 0 - 1 5 0 6 0 - 1 8 0 4 0 - 1 0 0 4 0 - 1 0 0 3 5 - 8 0 2 5 - 4 0 15-30

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Btorlne Flsherio Research and Management 8 Euthynnus qffinis

9 Sarda orientalis 10 Gymnosarda unicolor

Little t u n a Oriental bonlto Dogtooth t u n a

2 0 - 6 8 30-50 8 0 - 1 0 0

Table 2. Temperature range for distribution, preferred temperature and habitat relative size of t u n a s (as reproduced by Silas and PUlal, 1982) Sl.No.

1.

2.

3.

4.

5.

6.

7.

8.

Scientific Name

Sarda orientalis Euthynnus affinis Auxis thazard

•Temperature range for dlstribution(°C)

15-25 (15-22)

17-28 (18-23)

~ Katsuwonus pelamis 17-28 Thunnustonggol

T. albacares

T. obesus

T. alalunga

(19-23) - 18-31 (20-28)

11-28

14-23

"Preferred temperature range

(°C) Temperate/

tropical Tropical Tropical 15-29 25-32 23-32

11-15 (18-22)

14-18 (15-21)

"Jlabitat

Coastal to pelagic/medium

Coastal to pelaglc/medlum

Coastal to pelaglc/medlum Pelagic migrator/

medium Neritic, continental Pelagic/large

Deep, pelagic/

large Pelagic migrator/

large

• Laevastu a n d Rosa, 1963 •* S h a r p a n d Plrage. 1978

Figures in p a r e n t h e s i s indicate the t e m p e r a t u r e range for fishery.

Pood and feeding

Major items of food of the different species of t u n a s observed by various a u t h o r s , available in the published works are given In Table 3 . C r u s t a c e a n s (planktonlc a n d a d u l t s ) , molluscs, other teleost fishes (juveniles a n d adults) a n d bait fishes c o n s t i t u t e Important Items of their food. Other Items include

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fish eggs a n d larvae a n d pelagic polychaetes. It is evident from the table t h a t the feeding h a b i t of species change with their growth. Charybdis s p . consti- t u t e s the favoured food item of Thunnus albacares t a k e n by longline gear.

Table 3 . Food a n d feeding h a b i t s of E. affints, A. thazard, A. rochet a n d K. pelamis observed by various a u t h o r s .

Species Major food items Authors

K. pelamis C r u s t a c e a n s , cephalopods, larval a n d juvenile fishes a n d baitfishes

Raju 1964

K. pelamis Fishes, c u s t a c e a n s , squids, m e d u s a e , molluscs and p l a n t m a t t e r s

K. pelamis Sardtnella s p p . , A. thazard T. albacares Fishes, stomatopods, crab

larvae and other Crustacea

T h o m a s 1964

Pon Siraimmeetan, 1986

T h o m a s , 1964

T. albacares Fishes, c r u s t a c e a n s , cephalopods

Silas et al 1986

T. albacares

E. affints

E. affints (juveniles)

A. thazard young ones unidentified fish Teleost fishes, squids cuttle fishes, crabs

(Charybdys), stomatopods C r u s t a c e a n s , gastropods, cephalopods, v e r t e b r a t a (Pisces) fish larvae Whitebaits, planktonic c r u s t a c e a n s

Pon Siraimeetan, 1986

J o h n 1993

K u m a r a n , 1964

E. affints Sardtnella s p p . u n - identified fishes, skeletal r e m a i n s of fish

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A. thazard Polychaetes, Crustacea, Insecta chaetognatha, cephalopods and fishes

K u m a r a n , 1964

A. thazard C r u s t a c e a n s , molluscs, (juveniles) ascidians, fish eggs

and larvae

A. thazard

A. thynnoides (A. rochei)

Anchoviella, fish r e m a i n s , Loligo, fish larvae,

copepods, decapod larvae, a m p h i p o d s , Megalopa, pteropods

Sardinella spp., Anchoviella, s p p . Leiognathus,spp.carangids,

Crustacea a n d molluscs

K u m a r a n , 1964

S. orientalis S. orientalis (juveniles)

Crustacea, fishes Fishes

K u m a r a n , 1964 Pon Siraimeetan,

1986 S.orientalis Sardinella spp.,A. thazard

young ones, s q u i d s , skeletal r e m a i n s of fishes

T. tonggol Loligo, Sardinella spp., Sillago sihama, skeletal r e m a i n s of fishes

/. platypterus Sardinella spp., Kovala koval, Loligo s p .

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A g e a n d g r o w t h

E s t i m a t e d l e n g t h s a t d i f f e r e n t a g e s of E. affinis, A. thazard, T. tonggol, S.

orientalis, K. pelamis a n d T. albacares r e p o r t e d b y v a r i o u s a u t h o r s a r e p r e - s e n t e d i n T a b l e 4 .

T a b l e 4 . E s t i m a t e s of l e n g t h a t a g e of E. affinis, A. thazard, A. rochei, T.

albacares K. pelamis, T. tonggol a n d S.orientalis

Species Length at Age Authors

lyr II yr Illyr IV yr Vyr VI yr

E. affinis 31.43 46.60 57.14 64.44 69.50 A. thazard 29.20 42.20 50.30 55.00

T. tonggol 42.30 61.90 74.00 81.30 85.90 S. orientalis 44.70 58.00 63.00 65.00

K. pelamis K.pelamis K. pelamis

40.7 49.3 56.2 36.00 57.00 69.00 36.7 57.3 69.00

62.00

77.70

T. albacares 50.60 76.40 95.20 108.8 +118.30 T.albacares 50.6 76.9 95.2 108,8 118.7

T. albacares 51.3 84.4 105.6 119.3 128.1 125.9

133.8

Silas et al 1986 -00 - - 00-

- 00-

Appukuttan et al 1977 Silas etal. 1986 Madan Mohan and Kunhikoya,

1986 Silas etal.,

1986 Madan Mohan and Kunhikoya,

1986 Filial etal., 1993 S i z e a t m a t u r i t y , f e c u n d i t y a n d s p a w n i n g

T h e s i z e a t f i r s t m a t u r i t y , s p a w n i n g p e r i o d a n d f e c u n d i t y of E. affinis, A.

4 1 1

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Marine Fl»herie» Research and Management

thazard, A. rochei a n d K. pelamis are presented In Table 5. Spawning periods of different species have been found to vary considerably. However, broadly It can be stated t h a t E. ajfinis s p a w n s during the premonsoon (April-May) and post-monsoon (Oct-Nov) periods. The spawning period of A. rochei h a s been observed as d u r i n g the post-monsoon period of September-October. A spawn- ing peak for skipjack t u n a (Katsuwonus pelamis) h a s been observed during January-April. Available information on the fecundity of E. ajfinis, A. thazard, A. rochei and K. pelamis are also given In Table 5. The relationship between fecundity (F) a n d the size (L) of different species of t u n a s h a s been observed to be :

E. affinis Log F = - 3 . 6 6 2 1 9 + 2 . 3 6 1 1 1 log L A. thazard Log F = - 9 . 7 7 9 9 1 + 4.75748 Log L A. rochei Log F = -1.70881 + 1.50244 log L K. pelamis Log F = - 9 1 8 . 5 7 0 5 + 2 3 . 2 7 5 2 5 log L

Table 5. Size a t first m a t u r i t y , s p a w n i n g a n d fecundity of E. affinis, A.

thazard, A. rochei and K. pelamis as estimated/observed by various workers species Size a t 1st

maturity

Spawning period Fecundity

E. afflnis 43-44 cm (James et al, 1992)

Oct-Nov and Apl-May (James etal. 1992)

210000 to 680000 Ova/

spawning (Rao, 1964) 280000 egg/spawning

(Rao, 1964) Sep-Oct and to a

certain extent prolongs upto March (Muthlah. 1986) Apl-Sep (Rao, 1964)

May-Nov (Jones, 1960)

A. thazard 30 cm August-Nov 6,01000 ova/Spawning (James etal, 1992

(saasige^

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A. rochet

K. pelarrds

23 cm (James et al, 1992)

40-45cm (Raju, 1964)

Oct-Nov (Muthiah , 1986)

Dec-Jan (Jones &

Kumaran, 1963) Aug-Sep (Rao, 1964)

Sep (Muthiah 1986) 52,000 Ova/spawning Sep-Oct (James et (Silas 1969)

al 1992)

Feb-July 3 1 7 6 0 0 - 1 3 3 2 9 0 0 (Raju, 1964) (Raju, 1964)

4 4 - 4 5 cm T h r o u g h o u t the year 1,70,000-680000 ( J a m e s et al, a t Minlcoy (Madan Mohan &

1992) Kunhikoya, 1986) March-April

(Yohannan et al, 1992)

Jan-Apl Sept-Dec.

(James et.al, 1992)

Fishery

Major gears

The major gears employed in the t u n a fishery are drift gillnets, hpoks a n d lines, p u r s e seines, pole a n d lines a n d troll-lines. Long line gear is employed in the fishery for yellowfin t u n a a n d deep-living big eye t u n a . Detailed information on the craftf a n d gears employed in the t u n a fishery h a s been given by Silas and Pillai {1982, 1986).

Trend in production

The t r e n d in the a n n u a l all-India t u n a production d u r i n g t h e y e a r s 1965-1996 is presented in Fig. 1. The total t u n a catch in India in the small scale sector fluctuated between 4 5 0 0 t (1965) a n d 4 6 , 9 0 0 t in 1990. A pro-

< 4 T 3 >

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Marine Fisheries Re»earch and Management

gresslve Increase In the t u n a catch was recorded from 1965 to 1996. T u n a production showed fluctuations and oscillations since 1965, and between 1982 and 1990 It ranged between 2 2 , 5 9 0 t and 4 6 , 9 9 0 t. Subsequently, the catch stabilised between 3 0 , 9 0 0 t (1991) and 4 5 , 0 0 0 t (1996). Of the total catch, a s an average (1982-96), 77.6% h a s been landed from the west coast of India, 16.8% from t h e e a s t coast, 5 . 1 % from L a k s h a d w e e p a n d 0 . 5 % from t h e A n d a m a n and Nicobar Islands. A state-wise comparison of t u n a production indicates t h a t along the west coast of India, Kerala r a n k e d first (56.8%) followed by Gujarat (19.2%), K a r n a t a k a (11.6%), M a h a r a s h t r a (10.2%) and Goa (2.2%) (Fig.2). Along the e a s t coast, the contribution by Tamil Nadu was maxi- m u m (69.0%) followed by Andhra Pradesh (24.5%), Pondlcherry (3.0%), Orissa (3.0%) a n d West Bengal (0.5%)(Flg.3).

The overall species composition of t u n a fishery indicates t h a t E. affinis c o n s t i t u t e the major component (56%) followed by A. thazard a n d A. rochei (18%), T.tonggol (6%), K. pelamis (4%) and other t u n n i e s including T. albacares a n d S. orientalis (16%) (Fig. 4).

Fig. 1. Tuna landings in India during 1965-'96

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35000

Fig. 2. Tunna landing In West coast (1982-'96)

i I I

Fig. 3. Tuna landing In east coast (1982-'96)

" 4 1 ^

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The total fish landing a n d total t u n a landing in Lakshadweep are shown in Fig.5. T u n a catch fluctuated between 1,760 t in 1980 (60.8% of total fish catch) a n d 11,566 t in 1994 (92.9% of total fish catch). T u n a landings showed a steady increase from 1980 and reached a peak in 1987. Subsequently, an all time peak landing of 11566 t was observed in 1994. Skipjack t u n a con- stituted a b o u t 78%, followed by young ones of yellowfin t u n a (12%) and other t u n a s s u c h a s E. affinis, A. thazard, and Gymnosarda unicolor.

T h e o v e r a l l s e a s o n a l p a t t e r n of t u n a f i s h e r y i n d i c a t e s t h a t t h e

Fla.4 ParcanUg* composition of differant •pacles of tunas landed In India during 1d82-'96

Other tunnies 16%

T. tonggol • / 6%

Fig. 4. Percentage composition of different species of tunas landed in India during 1982-'96

jDTaWtMdngs)

iMiil

i i i a s i 8 I i i i i i i

i i

Fig. 5. Total production of tunnas and its contribution to the total landings in Lakshadweep Islands during the period 1979-'94

CIII^>

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p r e - m o n s o o n a n d m o n s o o n s e a s o n s a r e t h e productive p e r i o d s along t h e south-west coast of India and the post-monsoon period along the M a h a r a s h t r a a n d Gujarat c o a s t s thereby Indicating a s e a s o n a l shift in their concentration.

In Lakshadweep, the December to February period was observed to bring the m a x i m u m c a t c h e s of t u n a s . However, the changed p a t t e r n of m e c h a n i s a t i o n / motorisation of the craft employed in the t u n a fishery h a s altered the t u n a fishery scenerlo, with continued operation d u r i n g monsoon period also.

S t o c k a s s e s s m e n t

Available information on the population p a r a m e t e r s (LOQ K & t^ ) a n d the r e s u l t s of stock a s s e s s m e n t s of E. affinis, A. thazard, A. rochei, K. pelamis, T. tonggol and T. albacares, estimated by various a u t h o r s are p r e s e n t e d in Tables 6 & 7.

Table 6. Population p a r a m e t e r s of E. qffinis, A. thazard, A. rochei, K. pelamis.

T. tonggol and T. albacares estimated by various a u t h o r s E. qffinis A. thazard S. orientalis K. pelamis

(cm) (cm) (cm) (cm)

T. albacares T. tonggol (cm) (cm)

0.22 0.32

to

LOD 81.00 K 0.3655

63.00

0.4898

-0.34 (Appukuttan et al., 1977)

66.00 90.00 145.00

1.0005 ^0.4898 ^0.3200

93.00 0.4898 to -0.3438 -0.2700 -0.1300 -0.0600 -0.3400 -0.2400

(Silas et al., 1986) Lcx>

K to

Loo

Loo K

8 3 . 5 0 0.420

5 6 . 0 0 0.770

9 0 . 0 0 0 . 4 8 9 8 -0.06

(Madan Mohan & Kunhlkoya, 1986) A. rochei

37.00 0 . 6 3 8

C^TT"

8 4 . 3 145.00

8 0 . 1 9 0.650

9 4 . 0 0 0.480

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Marine Fisheries Research and Management

L o j

K

8 3 . 5 0.42

5 6 . 0 0 0.77

3 7 . 0 0 0.60

(James et al. 1992) 8 0 . 1 9

0.650 (James etal, 1993)

9 4 . 0 0 0.48

Table 7. Stock a s s e s s m e n t of E. affinis, A. thazard, A. rochei, T. albacares, T. tonggol a n d K. pelamis estimated by various a u t h o r s (in

tonnes)

E.a A.t. A.r. T.a. T.t. K.p.

M S Y

Biomass M S Y

15526 4852 24310 1982

896 612

641 4440 722 3702 (James et al., 1992)

MSY 2 5 8 9 6 3 9 4 6 1457

(Kerala) (Kerala)

3 0 6 9

Biomass MSY 2 8 9 1 7 2 2 5 4 6 9 5 (Kerala) (Kerala)

2683

MSY 5 1 8

(T.Nadu)

Biomass MSY 3 1 4

(T. Nadu)

(James etal, 1993)

MSY 620 (Filial etal., 1993)

In *he p r e s e n t report the r e s u l t s of stock a s s e s s m e n t (James et al. 1992) based on the d a t a collected during 1984-88 are presented. E s t i m a t e s of popu- lation p a r a m e t e r s were m a d e for six species viz., E. affinis, A. thazard, A.

rochei, T. albacares, T. tonggol a n d K. pelamis. The r e c r u i t m e n t p a t t e r n indi- cated two p u l s e s for little t u n a , longtail t u n a , frigate t u n a a n d bullet t u n a

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a n d only one p u l s e for skipjack t u n a . The r e s u l t s of analysis Indicate t h a t for all the species the exploitation r a t e (F/Z) ranged from 0.05 to 0.80. For E.

affinis, t h e decrease In effort to 66% of the c u r r e n t level would yield 3 4 1 t o n n e s . The p r e s e n t level of exploitation r a t e for T. tonggol is 0.499 with t h e e s t i m a t e d yield of 6 2 3 t o n n e s . It can be increased by 1.6 t i m e s to obtain t h e MSY of 642 t o n n e s . The MSY estimate for A. thazard is 4 8 5 2 t o n n e s which c a n b e obtained by Increasing the effort by 1.2 t i m e s . With r e s p e c t to A.

rochei, t h e MSY of 8 9 6 t o n n e s c a n b e obtained by increasing t h e effort by 1.6 t i m e s . For skipjack the estimated MSY of 4 4 4 0 t o n n e s c a n be obtained by Increasing the effort by 4.1 times to realize a n additional yield of 3 0 0 t o n n e s . This analysis indicates t h a t t h e t u n a stocks in the traditional coastal sector are exploited to the near optimum level. However, the migratory n a t u r e of t u n a s does not support this conclusion. Recent reports indicate t h a t after the expansion of the a r e a of operation the longtail (Thunnus tonggol) a n d the yellowfin (T. albacares) t u n a s are the d o m i n a n t species in the drift gillnet fishery in the north-west sector. With regard to t u n a live-baits, the economic utilisation a n d e n h a n c e d exploitation of all the species from the n o r t h e r n Islands could e n h a n c e the t u n a production in Lakshadweep.

Suggestions for future research

Existing d a t a b a s e to be s t r e n g t h e n e d by improving t h e system of d a t a collection t h r o u g h increasing t h e sampling coverage to enable stock a s s e s s m e n t of coastal a n d oceanic t u n a s . Extensive length frequency d a t a s h o u l d be collected both from t h e coastal a n d oceanic fisheries, with well p l a n n e d sampling. The National Marine Living Resources D a t a Centre (NMLRDC) of CMFRI should b e s t r e n g t h e n e d in associa- tion with FSl a n d the fishing Industry.

The existing production models may b e critically evaluated for their suitability to a s s e s s the s t a t u s of t u n a s t o c k s . If n e c e s s a r y , suitable p r o d u c t i o n models need be developed to assess the stocks of migratory fish groups.

Tagging experiments for studying the migration of oceanic t u n a s may be initiated in the Indian EEZ in collaboration with International agencies. Co-operative tagging programme with countries in the region s h a r - ing the s a m e stocks, viz., India, Thailand a n d Indonesia in the A n d a m a n

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sea, may be mooted. A programme for tagging may be taken u p with t h e involvement a n d s u p p o r t of lOTC.

S t u d i e s on t h e early life-history of t u n a species h a s to be considered.

Specific programme of r e s e a r c h on the spawning and the larval stages of t u n a s in the Indian w a t e r s may be u n d e r t a k e n . Biological s t u d i e s , s t u d i e s on m e r i s t i c c h a r a c t e r s , food c o n t e n t s t u d i e s etc may be strengthened. Greater a t t e n t i o n may be given to the environmental a s - pects of t u n a s . The s t u d i e s may be continued for s u c h a reason- able period as required for arriving at any predictable conclusion.

Apart from SST, the effort may also be directed on other environmental meteorological p a r a m e t e r s Influencing t u n a distribution and a b u n d a n c e . S t u d i e s may b e m a d e to establish the linkage between environmental d a t a a n d commercial t u n a fishing data.

Effective training of the manpower for t u n a fishing need to be organised in the form of a c r a s h programme by FSI/CIFNET, seeking the s u p - port if n e c e s s a r y from the UN agencies s u c h a s FAO.

Documentation a n d extension activities of the I n s t i t u t e s s u c h as FSI/

CMFRI/MPEDA h a s to be s t r e n g t h e n e d . Options for tuna fishery development

Diversification of crafts a n d gears in the small scale sector especially t h r o u g h greater u s e of m e c h a n i s e d drift gillnetters a n d other suitable gears. Such as monofilament longllnes.

Motorization of t h e small crafts s h o u l d be further encouraged for ena- bling the small scale fishermen to expand the a r e a s of operation result- ing in higher yields a s exemplified along the s o u t h w e s t coast of India, Considering the need for diversifying the existing fishing effort, a part of the fishing fleet engaged in shrimping may be diversified for t u n a fishing. The deep sea s h r i m p trawlers, sona b o a t s a n d mini trawlers may be considered in t h i s scheme especially for monofilament longllning.

Mobility of t h e p u r s e - s e i n e vessels is a critical factor in t a p p i n g large s h o a l s of t u n a s , t h e occurrence of which h a s been reported by earlier

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a u t h o r s in the nerltic belt of Indian EEZ.

It was recommended earlier to introduce 150 longliners each with a capacity to c a t c h a r o u n d 450 t of t u n a annually.

It will be worthwhile to Initiate commercial p u r s e s e i n e fishing in the Indian EEZ and contiguous high seas. Recent developments in the p u r s e seine activity by the i n d u s t r i a l sector in the w e s t e r n Indian Ocean a n d the r e s u l t a n t catch of yellowfin and skipjack t u n a s from the tropical w a t e r s of Indian Ocean are encouraging. Succesful p u r s e s e i n e s e a s o n s were demarcated in the Lakshadweep Area a s November to May and in the Andaman sea a s March to May. Employment of 10-20 p u r s e seiners, (industrial type 59-72 m OAL) with a n a n n u a l fishing capacity of 6 0 0 0 t, a n d 20 s u c h p u r s e seiners each with a n n u a l fish- i n g / p r o d u c t i o n capacity of 4 0 0 0 t, would lead to t h e p r o d u c t i o n of

110,000 t of t u n a s from t h e oceanic waters of Indian EEZ a n d contigu- o u s a r e a s .

Potential r e s o u r c e s of t u n a s in Lakshadweep h a d been estimated variedly (60,000 t - 90,000 t). In view of the strategic importance of i n s u l a r a r e a s coupled with the focus on conservation of ecosystem a n d anticipated i m b a l a n c e s in the small scale sector by the introduction of large scale i n p u t s , the p l a n s are suggested for development of t u n a fishery in the insular area in the following lines:

Existing pole a n d line b o a t s (7-9 m OAL) could b e effectively modified with chilling a n d storage facilities. Adoption of m e c h a n i s e d sea water s p r a y system would economise utilisation of live-baits.

Introduction of a new generation of 15-20 m OAL b o a t s with a d e q u a t e navigational, chilling and storage facilities, a s 2-3 days fishing would e n h a n c e the a r e a a n d d u r a t i o n of fishing. Introduction of 80 b o a t s of this size would produce 60-100 t of t u n a s per boat per a n n u m . Shortage of manpower a n d expertise h a s b e e n pointed o u t a s con- s t r a i n t s for t h e development of s u c h p r o g r a m m e s . This problem h a s to b e solved by effecting inter-island movements of f i s h e r m e n / b o a t t h r o u g h a p p r o p r i a t e incentive s c h e m e s . Required t r a i n i n g in m o d e r n m e t h o d s of t u n a fishing u n d e r Joint v e n t u r e p r o g r a m m e s n e e d s further

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Marine Flsherieg Research and Management consideration.

Experimental fishing by p u r s e s e i n e s , similar to the ones used in A n d a m a n sea by Thailand (14-24 m OAL purseseiner; n e t s 1400 m long a n d 120 m deep; 14-18 m OAL p u r s e s e i n e r n e t s 6 6 5 m long and

100 m deep) for fishing s u r f a c e s c h o o l s of Skipjack [Katsuwonus pelamfsAlongtail (Thunnus tonggol) a n d little t u n a (Euthynnus a/finis) by expertise developed by m a i n l a n d fishermen could be tried to propa- gate p u r s e seining a r o u n d the oceanic i s l a n d s by training and involving the local fishermen. The additional catch generated will be utilised in canning, masmin production a n d processing into frozen r o u n d fillets.

C o n s t r u c t i o n a n d installation of cheaper a n d long l a s t i n g FADs, which would r e d u c e scouting time for fishermen require u r g e n t a t t e n t i o n . Fishery forecasting system be developed a n d the r e s u l t s extended to the fishermen t h r o u g h extension service

For increasing value added p r o d u c t s , chilled water storage on board a n d freezing the c a t c h a s h o r e should be tried.

Masmin production should be t a k e n u p a t community processing level by providing the m u c h needed fuel for processing the t u n a meat.

Steam cooking, s m o k e h o u s e s etc s h o u l d be introduced to ease the production p r o c e s s .

Product development s u c h a s g r a n u l a t e d masmin, t u n a paste, t u n a pow- der a n d improvement of the quality of riha akru would e n s u r e more c o n s u m e r acceptance a n d b e t t e r r e t u r n s to the fishermen. Development of a n organised marketing system for masmin will be beneficial to the fishermen in getting proper m a r k e t a n d avoiding price falls.

Quality control a n d hygienic m e t h o d s of masmin production especially in the n o r t h e r n i s l a n d s should be d e m o n s t r a t e d . In the n o r t h e r n is- l a n d s in the Lakshadweep nearly 3 0 - 3 5 % of t h e body p a r t s a r e wasted in the p r e p a r a t i o n of masmin. At Agatti in the n o r t h e r n i s l a n d s , on an average, a b o u t 1130t of t u n a m e a t are wasted per a n n u m , which would fetch Rs.16-17 l a k h s worth of first quality fish meal. Effective w a s t e

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utilisation m e t h o d s by converting them to fish meal or preserving the material by ensilaging for the p r e p a r a t i o n of cattle feed should be tried.

A c k n o w l e d g e m e n t

The a u t h o r s are thankful to Shrl M.N. Kesavan E l a y a t h u for all t h e a s - s i s t a n c e rendered In the p r e p a r a t i o n of this paper.

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