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
28 E x p l o i t e d s e e r f i s h fishery r e s o u r c e s of India - a review
C.Muthiah, H.M.Kasim and Uma S.Bhat
ABSTRACT
Seerfishes forming 1.7 % of the total marine Jish catch of the country are considered as one of the high value resources Andhra Pradesh (14.3%) and Tami Nadu (11.5%) on the east coast and Gujarat (22.8%). Maharashtra (16.9%) and Kerala (16.1%) on the west coast are the principal contributors of seerfish. They are caught mainly in gillnet (65.12%) and hook & line (6.96%) from 25-50 m depth zone and. in trawl (11.47%) operated from beyond 50 m depth.
Of the five species available in Indian waters, the fishery is sus- tained by the king seer Scomberomorus commerson and the spot- ted seer S.guttatus. The stock assessment studies on the king seer revealed that the present yield in different regions of the coun- try are closer to MSY. However there is scope for stepping up pro- duction by extending fishing operations to the deeper waters be- yond 50 m depth. The paper reviews their fishery, biology and stock characteristics in Indian waters.
Introduction
Species belonging to the genera Scomberomorus, Acanthocybium a n d Grammatorcynus of the family Scombridae popularly known a s seerfishes/
Spanish mackerels, are esteemed food fishes in all p a r t s of the world. Out of the 19 species known u n d e r these four genera, only five species, viz., the king seer S.commerson, the spotted seer S.guttatus, the streaked seer S.lineolatus, the Korean seer S.koreanus; and the whaoo Acanthocybium solandri are known to occur in the Indian s e a s . S.commerson and S.guttatus are the most a b u n -
Exploited seerflsh fishery resources of India - a review dant, while S.lineolatus a n d A.solandri are c a u g h t sporadically In certain p a r t s of our s e a s .
The information available on the seerfishes of Indian w a t e r s p e r t a i n s to taxonomy, distribution, occurrence (Chacko 1956; Day 1865a, 1865b, 1869, 1878, 1889: Fowler 1927; Filial 1929; Spence a n d Prater 1 9 3 1 ; Vijyaraghavan 1955; J o h n 1959; Kaikini 1961; Rao 1961; J o n e s 1962a; J o n e s a n d K u m a r a n 1962; J o n e s a n d Silas 1962a, 1962b; Silas 1962a; DevaraJ 1976; Dhulkhed 1981), fishery (Russel 1803; Hornell 1917; Pillai 1929; Sorley 1933; Anony- m o u s 1 9 5 1 , 1958, 1959, 1960; K r l s h n a m o o r t h i 1957, 1958; Nayar 1958;
Kaikini 1961; Chacko et al. 1962; J o n e s 1962b; Silas 1962c; Bal a n d Rao 1984; Rao a n d Kasim 1985; Kasim a n d Khan 1986; D e s h m u k h a n d Sriram 1987; Yohannan and Balasubramanian 1989), food a n d feeding (Vijyaraghavan 1955; Anonymous 1959, 1960; V e n k a t a r a m a n 1961; B a s h e e r u d d i n a n d Nayar 1962; K u m a r a n 1962; Rao 1962; D e s h p a n d e and Sivan 1969; D h a w a n et al 1972; Devaraj 1977a), age and growth (Devaraj 1981; Kasim and H a m s a 1989;
Thiagarajan 1989), length-weight relationship (Krlshnamoorthi 1958; Devaraj 1981), m a t u r a t i o n a n d spawning (Anonymous 1959; Krlshnamoorthi 1958;
Devaraj 1983a, 1986b, 1987) eggs, larvae a n d Juveniles (Vijyaraghavan 1955;
Krishnamoorthi 1958; Kaikini 1961; V e n k a t a r a m a n 1961; J o n e s 1962a; J o n e s a n d K u m a r a n 1962; Kumaran 1962; Rao 1962; Rao a n d G a n a p a t i 1997), p a r a - sites ( B a s s e t t - S m i t h 1898; Southwell 1929, 1930; Verma 1936; C h a u h a n 1953a, 1953b; Ramalingam 1951, 1961a, 1961b; Trlpathi 1954, 1957; Silas 1962b; Silas a n d Ummer Kutty 1962), physiology (Tampl 1959), osteology (Devaraj 1977b), curing (Day 1865a, 1878; Nicholson 1930 ), ecology (Hora 1953), r e s o u r c e s (Devaraj 1986a), stock a s s e s s m e n t (Banerji 1973, Devaraj 1977a, 1983b; Kasim a n d H a m s a 1989; Y o h a n n a n et al. 1992; Pillai et al 1994), sport fishing (Thomas 1897; Burton 1946; Macdonald 1947; S u t e r 1948) and utiUty as food (Pillai 1929; Day 1865a, 1865b, 1878).
The investigation carried out a t the CMFRl over the p a s t 5 decades is consolidated here u n d e r for the u s e of fishery m a n a g e r s , a n d e n t r e p r e n e u r s (fishing i n d u s t r y ) . The r e s e a r c h r e s u l t s also give scope to formulate future r e s e a r c h p r o g r a m m e s leading to j u d i c i o u s m a n a g e m e n t of the r e s o u r c e . Data base
Statewise, gearwise and quarterwise d a t a on estimated catch a n d effort 427
Marine Fisheries Research and Management
from all maritime s t a t e s of India for 1989-94 collected by Fisheries Resources A s s e s s m e n t Division of the I n s t i t u t e were u s e d for catch per u n i t effort analy- sis. As the resource Is exploited by a variety of m e c h a n i s e d a n d non-mecha- nised gears, the effort is s t a n d a r d i s e d by following the method adopted by Silas a n d Pillal (1985).
Fishery
Seerfishes are distributed in tropical a n d subtropical w a t e r s of Indian, Pacific a n d Atlantic O c e a n s . Among the seerfishes occurring In the Indian s e a s , S. commerson, is the most widely distributed species, followed by S.
guttatus, S. lineolatus, Acanthocybium solandri a n d S. koreanus.
Seerflsh landings in India during 1959-1994 indicate an Increasing trend over the years from 6,590 t in 1959 to 4 2 , 1 4 0 t in 1992 with a n n u a l fluctua- tions (Fig. 1). The average a n n u a l l a n d i n g of 10,499 t d u r i n g the decade
1960-69, h a s almost doubled to 2 0 , 3 0 0 t In the next decade 1970-79 a n d further Increased to 3 3 , 2 9 7 t in 1980-89. In the recent five-year period, 1990-94, the average a n n u a l landing stood at 3 7 , 9 2 6 t which is a b o u t 5.5 times more t h a n t h a t of 1959, 3.6 times more t h a n t h a t of 1960s a n d a b o u t 2 times t h a t of 1970s. This r e m a r k a b l e Increase from 1971 was due to inten- sification of m e c h a n i s a t i o n of crafts a n d gears a n d also t h e vulnerability of this resource to t h e trawling operations especially by multiday trawling In the deeper w a t e r s beyond 50 m d e p t h .
The a n n u a l average seerflsh yield of 2 9 , 0 5 8 t during the 25-year period of 1970-94 w a s constituted by e a s t coast a n d west coast a t a b o u t 4 0 % a n d 60% respectively. During 1950s more seerfishes were c a u g h t along the east coast (60%) (Jones, 1962b). During the seventies the seerflsh production by both coasts was a t 50:50 level (Devaraj, 1986a) which changed to 37:63 In 1980-89 a n d c o n t i n u e d a t t h e s a m e level (35:64) in t h e c u r r e n t five-year pe- riod of 1990-94. This clearly shows t h a t the growth of seerflsh production along the east coast Is declining w h e r e a s a n increasing trend is seen on the west coast.
In the east coast bulk of the seerflsh catch during 1970-94 period was made by Andhra P r a d e s h (41%) a n d Tamil Nadu (40%). Along the west coast Kerala (28.93%), M a h a r a s h t r a (26.55%) and Gujarat (26.66%) were t h e prime c o n t r i b u t o r s .
Caleb (siooot)
Exploited geerflsh flghery resources of India - a review
% IB total eaiek
1959 1965 1971 1977 1983 1989
Fig. 1 Estimated annual seerflsh landings in India during 1959-'94 Craft and gear
Different types of crafts are employed for seerflsh fishery depending upon the prevailing regional environmental conditions. They are dugout canoes, plank built canoes, FRP canoes, outrigger canoes and small/medium trawl type boats of 6.75-14.5 m. Besides, catamarans are also common crafts for seerflsh along the east coast. While all the small/medium trawl boats and indigenous plank built/FRP boats are mechanised, the small canoes and cata- marans have also recently been motorlsed with outboard engines. Consequent to the motorisation the number of the non-mechanised plank-built boats, ca- noes and catamarans are on the decline.
Among a variety of gears used for the capture of seerflsh the gillnets are the most popular along both east and west coasts of India, hooks & lines are common on the east coast. In recent years trawls are emerging as one of the Important gears for Juvenile seerflsh exploitation in many of the states.
Seerflshes are also taken along with other fishes by various gears like shoreseines, boatseines, longlines and surface trolling. Purse seines along
c:^^9^
Marine Fisheries Research and Management
the west coast also land them a s Incidental c a t c h e s . Glllnets with larger m e s h size of 120-170 mm have been found very efficient for seerflsh exploita- tion. Hook & lines are also found to b e efficient a n d highly selective. Trawls and s h o r e seines are non-selective a n d usually c a t c h small sized seerfishes (Kasim a n d H a m s a , 1989).
Catch, effort and c a t c h rates
Gillnet: On a n average t h i s d o m i n a n t gear landed 2 4 , 9 0 4 t of seerflsh forming 6 5 . 1 1 % of the total seerflsh production of the country during 1989-94 (Table 1). The bulk of the catch, 6 7 . 7 3 % (16,799.5 t) was landed along the west coast a n d the rest on the e a s t coast. The a n n u a l landings by the gear varied from 46 t in Pondicherry to 3,021.8 t In A n d h r a Pradesh along the east coast a n d from 9 4 4 . 8 t in Goa to 5,863.5 In Gujarat on t h e west coast. The percentage contribution of seerflsh by the gear varied from 53.30 (Pondicherry) to 9 8 . 5 1 (West Bengal). The total average s t a n d a r d gillnet effort for seerflsh d u r i n g 1989-94 was 14.47 lakh u n i t s comprising 53.62% on the east coast and 4 6 . 3 8 % on the west coast. The effort was lowest along the Pondicherry coast (4,823 units) and highest along the Orissa coast (1,85,451 u n i t s ) . Along the west coast minimum effort was in K a r n a t a k a (27,938 units) a n d maxi- m u m in Kerala (1,38,841 units) (Table 2). The average c a t c h r a t e (C/SE) for all-India was 17.21 kg d u r i n g 1989-94 and It was 17.30 kg during 1964-81 (DevaraJ, 1986a). The catch rate for t h e east coast (10.44 kg) w a s m u c h lower t h a n t h a t for west coast (25.03 kg). Along the east coast, the catch r a t e was highest for A n d h r a P r a d e s h (20.43 kg) and lowest for Tamil Nadu (6.48 kg).
Among the west coast s t a t e s , highest catch rate was recorded in K a r n a t a k a (54.18 kg) a n d lowest in Gujarat (17.35 kg). Analysing the catch a n d effort d a t a for 1964-81, DevaraJ (1986a) reported the C / E for e a s t coast a n d west coast a s 14.9 kg a n d 2 0 . 5 kg respectively (Table 3). Highest C / E was re- corded by A n d h r a P r a d e s h (26.5 kg) followed by Tamil Nadu (11.9 kg), Orissa (10.2 kg) and West Bengal (6.5 kg) on the east coast sector a n d on the west coast it was h i g h e s t for M a h a r a s h t r a a n d Gujarat (41.3 kg each) followed by K a r n a t a k a a n d Goa (31.9 kg each) and Kerala (11.76 kg). Comparing the C/
E of the above two periods. It is seen t h a t in recent years the a b u n d a n c e of seerflsh h a s slightly increased along the west coast with proportionate reduc- tion in the east coast.
Exploited seerflsh fishery resources of India - a review Table 1. Gearwise average (1989-'g4) Catch of seerfishes (t) in different s t a t e s
(figures in parenthesis indicate %)
State Gillnet Hook&line Trawl Other gears
Total
West Bengal Orlssa Andhra Pradesh Tamil Nadu Pondl- cherry
1061.6 (98.51) 1695.5 (68.73) 3 0 2 1 . 8 (54.56) 2280.0 (53.35) 46.0 (53.30)
0 (0) 339.0 (13.74) 881.2 (15.91) 799.0 (18.70) 28.0 (32.44)
0 . 5 (0.05) 56.0 (2.27) 195.3 (3.53) 531.0 (12.43) 1.3 (1..51)
15.5 (1.44) 376.3 (15.26) 1440.3 (26.00) 663.0 (15.52) 11.0 (12.75)
1077.6 2 4 6 6 . 8
5538.6 4 2 7 3 . 0
86.3
E a s t coast
8104.9 (60.30)
2047.2 (15.23)
784.1 (5.83)
2 5 06. 1 (18.64)
13442.3
Kerala Karnataka G o a
Mahara- s h t r a Gujarat
4717.0 (72.92) 1513.7 (77.64) 944.8 (85.50) 3 7 6 0 . 5 (54.13) 5 8 6 3 . 5 (70.35)
498.8 (7.71) 22.7 (1.16) 0 (0) 90.0 (1.29) 3 . 3 (0.04)
714.5 (11.05) 237.3 (12.17) 25.9134.3 (2.34) 1715.8 (24.70) 908.0 (10.90)
538.0 (8.32) 176.0 (9.03 1105.0 (12.15) 1381.0 (19.88) 1559.4 (18.71)
6468.3
1949.7
6 9 4 7 . 3
8334.2
West coast
16799.5 (67.73)
614.8 (2.48)
3601.5 (14.52)
3788.7 (15.27)
2 4 8 0 4 . 5
Total 24904.4
(65.11)
2662.0 (6.96)
4385.6 (11.47)
-C43r>
6 2 9 4 . 8 (16.46)
3 8 2 4 6 . 8
Marine Fisheries Regearch and Management
T a b l e : 2 E s t i m a t e d effort, c a t c h a n d c a t c h r a t e s of s e e r f l s h e s b y g i l l n e t t e r s d u r i n g
S t a t e
W e s t B e n g a l O r l s s a
A n d h r a P r a d e s h T a m i l N a d u P o n d l c h e r r y E a s t c o a s t K e r a l a K a r n a t a k a G o a
M a h a r a s h t r a G u j a r a t W e s t c o a s t A l l - I n d i a
1 9 8 9 - ' 9 4 (average) i n d i f f e r e n t m a r i t i m e s t a t e s . S t a n d a r d
effort (units) 8 6 , 2 9 1 1 , 8 5 , 4 5 1 1 , 4 7 , 9 2 2 3 , 5 1 , 6 6 1 4 , 8 2 3 7 . 7 6 , 1 4 8 1 , 3 8 , 8 4 1 2 7 , 9 3 8 2 8 . 9 0 5 1 , 3 7 , 6 2 0 3 , 3 7 , 9 1 7 6 , 7 1 , 2 2 1 1 4 , 4 7 , 3 6 9
C a t c h (c) (T) 1 , 0 6 1 . 6 1 , 6 9 5 . 5 3 , 0 2 1 . 8 2 , 2 8 0 . 0 4 6 . 0 8 , 1 0 4 . 9 4 , 7 1 7 . 0 1 , 5 1 3 . 7 9 4 4 . 8 3 , 7 6 0 . 5 5 , 8 6 3 . 5 1 6 , 7 9 9 . 5 2 4 , 9 0 4 . 4
C / S E (KG) 1 2 . 3 0 9 . 1 4 2 0 . 4 3 6 . 4 8 9 . 5 4 1 0 . 4 4 3 3 . 9 7 5 4 . 1 8 3 2 . 6 9 2 7 . 3 3 1 7 . 3 5 2 5 . 0 3 1 7 . 2 1
C / E * (KG) 6 . 5 0 1 0 . 2 0 2 6 . 5 0 1 1 . 9 0 - 1 4 . 9 0
1 1 . 7 6 3 1 . 9 0 3 1 . 9 0 4 1 . 3 0 4 1 . 3 0 2 0 . 5 0 1 7 . 3 0 SE=Standard effort
•Catch per boat days a s reported by Devaraj (1986a) 1964-'81 period
Table : 3 Estimated effort, c a t c h and catch rates of seerflshes by hook and l i n e s during 1 9 8 9 - 9 4 (average) i n different maritime s t a t e s . S t a t e
W e s t B e n g a l O r l s s a
A n d h r a P r a d e s h
S t a n d a r d effort (units) No HL fishery 3 , 6 8 , 3 2 5
1 , 9 9 , 7 4 7
cr'432~'^)—
C a t c h (c) (T)
3 3 9 . 0 8 8 1 . 2
C / S E (KG)
0 . 9 2 4 . 4 1
Tamil Nadu Pondlcherry East coast
Exploited seerfish 2,85,550
1,720 8 , 5 5 , 3 4 2
fishery resources 799.0
28.0 2 , 0 4 7 . 2
of India - a review 2.80
16.28 2 . 3 9 Kerala
K a r n a t a k a Goa
M a h a r a s h t r a Gujarat
60,427 4 8 3
No HL fishery 21,530 6,393
498.8 22.7
90.0 3 . 3
8.25 47.00
4.18 0.52
West coast 8 8 , 8 3 3 6 1 4 . 8 6 . 9 2 All-India 9 , 4 4 , 1 7 5 2 , 6 6 2 . 0 2 . 8 2
SE=Standard effort, HL = Hook and Line
Hook & line: This gear contributed 2,662 t of seerfish a n n u a l l y during 1989-94 forming 6.96% of the total all-India seerfish landings (Table 1). E a s t coast recorded higher landings (2,047.2 t) by a b o u t 3 times more t h a n the west coast (614.8 t). There was no landing of seerfish by this gear in West Bengal a n d Goa. In other s t a t e s it accounted 0.04% (Gujarat) to 3 2 . 4 4 % (Pondlcherry). The catch was highest in Andhra P r a d e s h (881.2 t) followed by Tamil Nadu (799 t). Along the west coast Kerala landed the m a x i m u m catch of 4 9 8 . 8 t. The average a n n u a l hook & line effort was 9.44 lakh u n i t s . Of this, a b o u t 9 1 % (8.55 lakh units) of the efforts were expended by the east coast s t a t e s and the rest by the west coast s t a t e s . Among all s t a t e s Orissa, Tamil Nadu, A n d h r a Pradesh a n d Kerala expended 3 9 . 0 1 % , 30.24%, 2 1 . 1 6 % and 6.40% of total effort respectively (Table 3). The average a n n u a l catch per unit effort was 2.82 kg, 2.39 kg and 6.92 kg for all-India, e a s t coast and west c o a s t r e s p e c t i v e l y . It w a s h i g h e s t for K a r n a t a k a (47.00 kg) followed by Pondlcherry (16.28 kg) a n d Kerala (8.25 kg).
Trawl : Seerfish landings by trawl a m o u n t e d to 4 , 3 8 5 . 6 t a n n u a l l y d u r - ing 1989-94. West coast contributed (3,601.5 t), nearly 4.5 times more t h a n east coast (784.1 t). Along the east coast Tamil Nadu recorded the highest landing of 531 t. In the west coast higher c a t c h e s were from M a h a r a s h t r a (1,715.8 t), Gujarat (908 t) and Kerala (714.5 t). The percentage c o n t r i b u t i o n
Marine Fisheries Research and Management
by t h i s gear was lowest In West Bengal (0.05) a n d highest in M a h a r a s h t r a (24.7). The total a n n u a l all-India trawUng effort w a s a b o u t 169.54 lakh h o u r s (Table 4). West coast s t a t e s expended more effort (105.23 lakh h o u r s - 62%) t h a n the east coast s t a t e s (64.31 lakh h o u r s - 38%). Tamil Nadu expended highest effort (43.92 lakh hours) on the east coast. Along the west coast M a h a r a s h t r a (35.50 lakh hrs.) and Kerala (30.47 lakh hrs.) expended higher efforts. The a n n u a l catch per h o u r (C/H) of seerflsh was 0.26 kg for all-India, 0.12 kg for e a s t coast a n d 0.34 kg for west coast and the C/H w a s higher for Gujarat (0.53 kg) a n d M a h a r a s h t r a (0.48 kg).
Table : 4 Estimated effort, catch and catch rates of seerfishes by trawlers during 1 9 8 9 - '94 (average) in different maritime s t a t e s .
State
West Bengal Orissa
Andhra Pradesh TamiJ Nadu Pondicherry East coast Kerala Karnataka G o a
M a h a r a s h t r a Gujarat West coast All-India
Standard effort (units) 45,169 5,91,682
13,17,859 43,92,474 83,595 6 4 , 3 0 , 7 7 9 30,46,984
17,40,879 4,73,739 35,50,437
17,11,156 1 , 0 5 , 2 3 , 1 9 5 1 , 6 9 , 5 3 , 9 7 4
Catch (c) (T) 0 . 5 56.0 195.3 531.0 1.3 7 8 4 . 1 714.5 237.3 25.9 1,715.8 908.0 3 , 6 0 1 . 5 4 , 3 8 5 . 6
C/SE (KG) 0 . 0 1 0 . 0 9 0 . 1 5 0 . 1 2 0 . 0 2 0 . 1 2 0.23 0.14 0.05 0.48 0.53 0 . 3 4 0 . 2 6 SE=Standard effort
Other gears: The other a r t i s a n a l gears a n d p u r s e seine (Kerala and Karnataka) together contributed 6,294.8 t (16.46%) a n n u a l l y (1989-94) to all-India catch of seerfishes. These gears accounted for 18.64% (2,506.1 t) in t h e east coast a n d for 15.27% (3,788.7 t) in the west coast. Among the s t a t e s .
Exploited seerftsh fishery resources of India - a review l a n d i n g s varied from 15.5 t In West Bengal to 1440.3 t in A n d h r a P r a d e s h along the e a s t coast a n d from 134.3 t in Goa to 1,559.4 t in Gujarat along t h e west coast.
Table 5: Average quarterwise seerfish landing in t o n n e s in different s t a t e s (1989-1994)
Q u a r t e r / State
I II III IV Total
West Bengal 175.3 (16.27
Orissa 885.0 (35.88)
Andhra Pradesh 2076.5 (37.49) Tamil Nadu 981.5
(12.5) Pondicherry 19.5
(22.6)
12.3 (1.15) 80.3 (3.25) 859.3 (15.51) 675.5 (15.81) 23.7 (27.46)
389.5 (36.14) 334.0 (13.54) 927.5 (16.75) 1415.7 (33.13) 35.8 (41.48)
500.5 (46.44) 1167.5 (47.33) 1675.3 (30.25) 1263.3 (29.56) 7.3 (8.46)
1077.6
2 4 6 6 . 8
5538.6
4273.0
86.3
Bast Coast 4 0 7 4 . 8 1651.1 3 1 0 2 . 5 4 6 1 3 . 9 (30.31) (12.28) (23.08) (34.32) Kerala
Kamataka
Goa
1253.8 (19.38) 272.5 (13.98) 166.8 (15.10) Mahaj-ashtra 1686.7
(24.28) Gujarat 2189.0
(26.26)
533.0 (8.24) 111.7 (5.73) 67.1 (6.07) 1088.6 15.67) 951.7 (11.42)
1027.3 (15.88) 205.3 (10.53) 228.3 (20.66) 895.5 (12.89) 500.8 (6.01)
3654.2 (56.49) 1360.2 (69.76) 642.8 (58.17) 3276.5 (47.16) 4692.7 (56.31)
13442.3
6468.3
1949.7
1105.0
6947.3
8334.2
-C435>
Marine Fisheries Research and Management West coast 5 5 6 8 . 8
(22.45) All-India 9 6 4 3 . 6
(25.21)
2752.1 (11.09) 4403.2 (11.51)
2857.2 (11.52) 5959.7 (15.58)
13626.4 (54.94) 18240.3 (47.69)
24804.5
3 8 2 4 6 . 8
Seasonal abundance
The a b u n d a n c e of seerfish over space a n d time d u r i n g 1989-94 are given in Table 5. The landings in the s t a t e s along the east coast showed no clear s e a s o n a l trend, w h e r e a s along the west coast the 4 t h q u a r t e r contrib- uted higher l a n d i n g s .
S p e c i e s c o m p o s i t i o n
D u r i n g 1 9 8 2 - 9 4 , t h e a l l - I n d i a s e e r f i s h c a t c h w a s c o n s t i t u t e d by S.commerson, 55.32%, S.guttatus. 43.92%, S.Uneolatus, 0.58% a n d A.solandri 0.18%. The percentage contribution of t h e first two d o m i n a n t species along both the east and west coasts was more or less same as the all-India figure (Table 6). The earlier study by Devaraj (1986) u s i n g the d a t a for 1964-81 reported higher national average for S.commerson (64.05%) a n d S.Uneolatus (2.65%) and lower for S.guttatus (33.30%). This shows t h a t exploitation of the latter species is on the increasing t r e n d . In general the two d o m i n a n t species show good agreement between the east and west coasts for similar latitudes (Devaraj, 1986a). The king seer is p r e d o m i n a n t along the s o u t h e a s t e r n (Tamil Nadu a n d Pondicherry coast), s o u t h w e s t e r n (Kerala coast) a n d mid-western (Karnataka and Goa coasts) regions. The spotted seer dominates along the n o r t h e a s t e r n region (West Bengal and Orissa coasts) a n d n o r t h w e s t e r n re- gion ( M a h a r a s h t r a a n d Gujarat coasts). The dominance of spotted seer in regions of n o r t h e r n l a t i t u d e s on both coasts coincides with the prevailing low salinity conditions due to heavy river discharges (Devaraj, 1986a).
Table 6: Species composition of seerfishes during 1 9 8 2 - 1 9 9 4 (average) (Figures in parenthesis indicates percentages)
State commerson
S.
guttatus
S.
lineolatus
A.
solandri
West Bengal 126.8
(18.33)
564.7 (81.65)
O.I (0.01)
0 (0.00)
Orlssa
Andhra Pradesh Tamil Nadu Pondicherry East coast Kerala Karnataka G o a
M a h a r a s h t r a Gujarat West coast All-India All-India*
(1964-81)
Exploited seerfish fishery 791.2
(42.73) 2132.8 (38.31) 3744.8 (87.29) 107.2 (94.87) 6 9 0 2 . 8 (55.16) 5024.7 (79.14) 2447.6 (81.73) 512.8 (58.05) 2206.1 (33.30) 2653.5 (41.93) 1 2 8 4 4 . 7 (55.41) 1 9 7 4 7 . 5 (55.32) (64.05)
1057.2 (57.10) 3 3 3 9 . 5 (59.98) 445.1 (10.37) 5 . 8 (5.13) 5 4 1 2 . 3 (43.25) 1295.2 (20.40) 540.7 (18.06) 370.6 (41.95) 4417.2 (66.68) 3640.1 (57.52) 1 0 2 6 3 . 8 (44.28) 1 5 6 7 6 . 1 (43.92) (33.30)
resources of India - a review 3 . 3
(0.17) 95.2 (1.71) 9 5 . 8 (2.23) 0 (0.00) 1 9 4 . 4 (1.55) 5 . 8 (0.09) 6 . 3 (0.21)
0 (0.00) 0 . 2 (0.003) 0 . 1 (0.001) 12.4 (0.05) 2 0 6 . 8 (0.58) (2.65)
0 (0.00) 0 (0.00) 4 . 5 (0.10) 0 (0.00) 4 . 5 (0.04) 23.4 (0.37) 0 . 1 (0.003) 0 (0.00) 0 . 5 (0.008) 34.6 (0.55) 5 8 . 6 (0.25) 6 3 . 1 (0.18)
* Source : Devaraj (1986a)
Migration
No direct evidence is availably on the migratory movements of seerfishes.
But they seem to move to inshore waters for feeding and to protected bays a n d coves In t h e shallow waters for breeding. These observations a r e b a s e d on the a b u n d a n c e of seerfish s p a w n e r s a n d on the d u r a t i o n of fishing sea- s o n s in t h e different locations. King seer s p a w n e r s move from t h e fishing g r o u n d s off Gulf of M a n n a r and C o r a m a n d a l coasts into t h e Inshore bays for spawning during the 2nd q u a r t e r and re-enter the fishing ground in the 3rd
"437"
Marine Flgherie» Research and Management
q u a r t e r (DevaraJ, 1986a). Maturing and ripe spotted seer occur In good a b u n - dance every year during M a r c h - J u n e period In the fishing g r o u n d s of the Gulf of M a n n a r and by November-December the s p e n t recovering fish migrate s o u t h towards the coast of Mundal a n d form appreciable fishery t h e r e . The occur- rence of this cycle every year signifies a n a n n u a l spawning migration (DevaraJ, 1987). The peak fishing season for S.commerson d u r i n g J u l y - S e p t e m b e r at Tutlcorin in the Gulf of M a n n a r , August-September at Cochin a n d September a t Calicut In the s o u t h w e s t coast, in October a t Mangalore-Malpe In the mid-west coast, October-January at Bombay and November-January at Veraval in the northwest coast (CMFRI a n n u a l r e p o r t s for 1992-93, 1993-94, 1994-95) is indicative of a s o u t h to n o r t h migration of t h e species. Devaraj (1986a) also reported t h a t t h e uniformly high a b u n d a n c e of seerflsh along the entire west coast In the last a n n u a l q u a r t e r a n d the progressive n o r t h w a r d Increase in the a n n u a l I n s t a n t a n e o u s mortality from the m i n i m u m off Cape Comorln to m a x i m u m for t h e Gujarat coast Indicates t h a t at least the king seer stock originates a r o u n d Cape Comorln a n d s p r e a d s (migrates) therefrom towards n o r t h .
Size distribution
The size of S.commerson in the bigger m e s h size glllnet (120-170 mm) at Madras, Tutlcorin, M a n d a p a m a n d Mangalore-Malpe and along the Kerala coast ranged from 220 to 1500 m m . The fishery w a s mainly s u p p o r t e d by 3 0 0 - 1 0 6 0 mm size g r o u p s , c o n s t i t u t i n g 8 9 - 9 7 . 5 % of the estimated n u m b e r of fish landed in different c e n t r e s . The proportion of fish below the length a t first m a t u r i t y (Im) of 750 mm^ranged from 3 4 . 5 8 % (Mandapam) to 77.57%
(Mangalore-Malpe) (Table 7). In the small m e s h size glllnet (60-100 mm) along the s o u t h e a s t coast centres, Tutlcorin and M a n d a p a m , the length range was 50-1250 mm. Bulk of the catch consisted of fish below minimum size at m a t u r i t y (80.65-99.99%). In trawl the size varied from 50 to 1150 mm at Madras, Tutlcorin and Mangalore-Malpe. The d o m i n a n t size groups were be- tween 120 mm a n d 620 mm. Almost all fishes (99.22-99.99%) c a u g h t by this gear from all c e n t r e s were below the size at first maturity. The hook & line catch at Tutlcorin a n d M a n d a p a m showed a wide r a n g e , 3 0 0 - 1 5 0 0 mm. The fishery w a s s u s t a i n e d mainly by 3 5 0 - 1 1 5 0 mm size g r o u p s (88.25-97.80%).
Exploitation of i m m a t u r e fish below Im was m i n i m u m at Tutlcorin (26.29%) a n d m a x i m u m a t M a n d a p a m ( 5 4 . 3 6 % ) . In t h e s h o r e - s e i n e fishery a t M a n d a p a m , the size varied from 50 to 1350 mm. The m a i n size groups were
"438"
Exploited seerflah fishery resourceg of India - a review between 150 a n d 1000 mm (97.9%). I m m a t u r e fish contributed a s m u c h a s 90%, as in the small m e s h size gillnet and trawl. S t u d i e s on the monthly size distribution of king seer in different gears at Tutlcorin showed t h a t youngfish (below 3 5 0 mm) o c c u r r e d in good n u m b e r s d u r i n g M a y - S e p t e m b e r in 'paruvalai'i gillnet with 120-170 mm m e s h size), April-November in trawl a n d t h r o u g h o u t the year in 'podivalai' (gillnet with 70-100 mm m e s h size). In h o o k & l i n e i m m a t u r e fish ( 4 5 0 - 7 5 0 mm) o c c u r r e d in all m o n t h s . At Mangalore-Malpe, youngfish a p p e a r e d In t h e gillnet (65-135 mm m e s h size) landings d u r i n g J a n u a r y and September-December a n d are very common in all m o n t h s of the fishery (August-January) in trawl. These observations indi- cate t h a t r e c r u i t m e n t to the fishery t a k e s place almost t h r o u g h o u t the year (Muthiah, per.com.).
Table : 7 S i z e d i s t r i b u t i o n of S.commerson by different gears and at different centres
Centre/ Gear Area
Madras Gillnet Trawl Mand^jam Gillnet (140mm) Gillnet (60mm) Gillnet (76mm) Hook & line Shore seine Tliticcm'Paruvalai' (Gillnet, 120-170 mm) 'Podivalai' (Gillnet,
Size range (mm)
100-1200 50-1150 250-1500
50-750
300-1250
300-1500 50-1350 240-1380
120-780
Dominant Size group
(mm)
300-900 150-500 500-1050
150-550
350-1050
350-1150 150-1000 360-1060
180-600
Proportion of dominant
size group
% 88-89 79.47 89,24
93,63
98,99
97,8 97,9 97,5
99,32
—t' /IQQ \ .
Proportion of Period Source Size group upto
Im (750mm)
% 71-24 99,22 34.58
99.98
80.65
54,36 89.99 61,74
99.59
1987 Thiagarajan (1989)
-
1984-87 Thiagarajan (1989)
"
- - -
1992-95 Kasim (Per,com,)
"
Marine Fisheries Research and Management 70-100 mm)
Hook & line 440-1460 Trawl 120-1000 Kerala GlUnet 300-1300 Mangalore Gillnet 220-1280
(65-135 mm)
Trawl 120-880 600-1120
120-600 500-890 320-920
88.25 97.77 - 96.74
26.29 99.30
77.57
200-620 99.38 99.99
1984-88 Yoharman et al.(1992) 1992-95 (Muthiah (Per.com.)
Age and growth . The published a c c o u n t s on the age a n d growth of seerfish of Indian
w a t e r s are very few. The earliest s t u d y was by Krlshnamoorthl (1958) on the spotted seer from Palk Bay. Later Rao (1978) studied the spotted seer from Waltair w a t e r s . DevaraJ (1981) studied the age and growth of all the three species from the s o u t h e a s t and s o u t h w e s t c o a s t s u s i n g length frequency method a n d otolith readings. Recently Kasim a n d H a m s a (1989), Yohannan et al (1992), Pillai et al. (1994) a n d Thiagarajan (1989) have determined age a n d growth of S.commerson u s i n g length frequency d a t a . The growth p a r a m - eters of the three species as estimated by different a u t h o r s are given in Table 8.
Table : 8 Estimates of growth parameters of Scomberomoms spp. in India water centres
Spedes Length Weight
Loo K/year to(year| Woo K/(year). to (year) Method of estimation Locali^ Source Imm) fn^ of growth parameters
Scomnerson 2081 0.21185-0.15955 39.027 0.21185 -0.03002 Rafailmethod PaUcBayS Derar^ 119811 m) Gulf of Mannar
1870 IFLI
1938 0-2006 -0.0835 32.002 0.2214 -0.1237 Petersen & Modal TuUcorin coast Kasim and Hamsa
(FL) Progression & 11989) Bagenal method
1775 0.38 -0.231 Ford-Walford plot Palk Bay & Tliiagarajan
Exploited geerflah fishery r o o u r c e s of India - a review
(FL)
1460 0.78
0,78 (FU
1460 (FL)
S.gumm 1278 018007 -0.4654 8.54 0.21256 -0.45267 Rafail method PaIkBay& DevaraJ (19811 Gulf of Mannar
Gulf of Mannar Modal progressi(» Southwest coast
of India EIi;FAN East & south
west coasts of India
(19891 PUlaletal.
(19941 Yohannan et d (1992)
S.Iineolatus Male
Female
1683 0.18232 -0.66433 15.7
1447 022314 -0.51225 24.3
Bagenal method Palk Bay &
Gulf of Mannar
Devaraj (1981)
Bagenal method Palk Bay & DevaraJ 11981) Gulf of Mannar
U-Total length, FL-Fork length.
DevaraJ (1981) u s e d two m e t h o d s viz., Rafail (1973) a n d Bagenal (1955) for the s t u d y of growth in length a n d weight a n d found t h a t the first method gives a b e t t e r fit for the von Bertalanffy equation in the case of S.commerson and S.guttatus. For S. lineolatus, the Bagenal method a p p e a r s to fit the growth better. His r e s u l t s on the s t u d y of back-calculated length of fish a t t h e time of ring formation on otolith agree closely with the r e s u l t of length frequency a n a l y s i s . He h a s shoWn t h a t all the three species develop two rings a year In their otolith at Intervals of six m o n t h s . He found t h a t in S.commerson the length at age derived from otolith s t u d i e s agreed well with t h o s e obtained from length frequency s t u d i e s . In the case of spotted seer, t h e lengths a t 1, 2 a n d 3 y e a r s estimated from length frequency analysis corresponded to the l e n g t h s a t 1.5, 2.5 a n d 3.5 y e a r s respectively estimated from otolith s t u d i e s a n d he a t t r i b u t e d these differences to the limitation of the length frequency d a t a to meet the r e q u i r e m e n t s of Petersen's method fully a s advocated by Watson (1964). According to him, Krishnamoorthl's (1958) estimation of third year class a t 3 8 5 mm (= 4 9 1 mm TL) a p p e a r s u n d e r estimated. The s t u d i e s made by Rao (1978) indicated t h a t the lengths at ages 1-7 a s 280 mm, 4 2 5 mm, 530 mm, 610 mm, 670 mm, 720 mm a n d 770 mm In S.L respectively.
The corresponding TL equivalents u p t o 1-4 years (337 mm, 5 1 3 mm, 641 mm
& 738 mm respectively) agree with the result obtained from the length fre-
Marine Fisheries Research and Management quency analysis by Devaraj (1981).
In the case of streaked seer Devaraj (1981) h a s shown t h a t the length at age from length frequency analysis was closer to the back-calculated esti- m a t e s for males t h a n for females.
According to Devaraj (1981) there is no significant difference in growth between male a n d females of all the three species. It Is seen from Table 9 that in S.commerson, low growth rate was reported by Devaraj (1981) and Kasim a n d H a m s a (1989) d u r i n g the 1st year of its life a t 4 0 2 mm and 382 mm respectively a s compared to very fast growth rate obtained by Filial et al. (1994) a n d Thiagarajan (1989) at 800 mm and 623 mm respectively. Recently Dudley et al. (1992) while studying the age and growth of this species from Oman waters reported t h a t fish of 40 cm in length entering the fishery were 1 year old and this observation Is in close agreement with t h a t of Devaraj (1981) and Kaslm and H a m s a (1989) on the species from Indian s e a s a n d Bouhlel (1985), C h e u n p a n (1988), Kedidi and A b u s h u s h a (1987) from other regions of the world. However, age a n d growth s t u d i e s by Dudley et al. (op. cit.) b a s e d on daily growth rings have shown t h a t the species grow very rapidly reaching a size of a b o u t 500-600 mm in 6 m o n t h s a n d to a b o u t 800 mm In 1 year. Simi- lar findings from Sri Lanka (Dayaratne, 1989), AustraUa ( McPherson, 1992) and Kuwait (Brothers and Mathews, 1987) also have been reported in recent y e a r s .
Table 9. Length (nun) at age of Scomberomorus spp. in Indian Waters
Species/
Age (Years) S.commerson S.commerson
S.commerson S.commerson
S.guttatus S.giMatus
1
402 382
623 800
369 280
2
726 665
1018 1130
532 425
3
995 907
1220 1322
640 530
4
1186 1088
1352 1410
610
5 6
1450 1420
670
7
720
TVpeof length TL FL
FL FL
n
770 SL
Source
Devaraj (1981) Kasim & Hamsa
(1989) Thiagarajan (1989)
Pillai et al.
(1994) Devaraj (1981)
Rao (1978)
Exploited seerfiah flghery resoMrces of India - a review (337 513 641 738 811 872 993) TL
S.Uneolatus 350 713 835 965 TL Devaraj (1981) TL - Total length, FL - Fork length, SL - Standard length.
The e s t i m a t e s of K reported by Devaraj (1981) a n d Kasim a n d H a m s a (1989) are very low a s compared to t h a t given by Thiagarajan (1989), t h o u g h the s t u d y area was t h e same in all the three c a s e s . Yohannan et al. (1992) also reported higher K value of 0.78 for the species. According to Thiagarajan (1989) the low K values may be due to the existence of several broods in tropics a s yearly cohorts for estimation of K following the modal progression a n a l y s i s .
L e n g t h - w e i g h t r e l a t i o n s h i p
The length-weight relationship of S.commerson of t h e Gulf of M a n n a r a n d Palk Bay w a s studied by Silas (1962c) Devaraj (19i31), Kasim a n d H a m s a ( 1 9 8 9 ) , T h i a g a r a j a n (1989). Filial et al. (1994) a l s o w o r k e d o u t t h e length-weight relationship equations of this species from s o u t h w e s t coast of India. The only s t u d y made on the length-weight relationship of the other two species, S.guttatus a n d S.Uneolatus was Devaraj (1981) from the above area.
It Is seen from the Table 10 t h a t the exponential values In the length-weight r e l a t i o n s h i p for all the three species is found to be close to 3 indicating iso- metric growth p a t t e r n .
The relationship between the total length a n d s t a n d a r d length of the spotted seer of the Rameswaram coast was studied by Krlshnamoorthl (1958) a s log Y = -0.0665 + 0.9771 log X where Y a n d X are the total a n d s t a n d a r d lengths respectively.
Table 10. Length-weight relationship (W^aL") p a r a m e t e r s of seerflshes i n Indian w a t e r s .
Species Group a b Length Region of study Reference
S.commerson Male& 8.37E-08 L i n cm 2.7536 FL Gulf of Mannar Silas (1962c) Females Win lbs
Males & 0.009614 Lin cm 2.8577 TL Palk Bay & Gulf Devaraj (1981)
< r 4 4 3 ^
Marine Fi«herie» Re«earch and Management
S.guttatus
S. lineolatus
Females
Maies
Females
0.01097
0.138
0.015424
0.01011
0.004394
0.004167
Wing Lin mm Wing Lin cm W i n g
•
•
2.8479
2.8296
2.8138
2.8605
3.0372
3.0443 FL
FL
FL
TL
Tl
Tl
of Mannar Gulf of Mannar
Palk B a y s Gulf of Mannar Southwest coast
of India Palk Bay & Gulf .
of Mannar Palk Bay & Gulf
of Mannar
•
Kaslm & Hamsa 119891
ITiingaraJan (1989)
Plllaletd.(1994)
DevaraJ 11981)
DevaraJ (1981)
DevaraJ (1981)
TL = Total length, FL= Fork length Food and feeding
S.commerson: According to DevaraJ (1977a) S.commerson from the Gulf of M a n n a r a n d Palk Bay feeds mainly on teleosts of a large n u m b e r of t a x a forming 9 9 . 3 6 % . It prefers Sardinella s p p . , c a r a n g l d s , Rastrelliger kanagurta, Hilsa kanagurta, Chirocentrus a n d Anchoviella s p p . (2.05%). King seer of Goa region feed on Sardinella spp.(S.gibbosa, S.Jirnbriata, S.sindensis, S.longiceps], Opisthopterus s p . R.kanagurta, w h i t e b a i t s a n d c u t t l e f i s h (Deshpande and Slvan, 1969; Dhawan et al. 1972). J u v e n i l e s of 51-150 mm (TL) prefer i4nchouiella s p p . a n d above 151 mm size o n w a r d s , Sardinella s p p . form the targeted food (Devaraj 1977a). Devaraj (1977a) observed t h a t the king seers pf all length a r e aggressive p r e d a t o r s . Rao (1962) found t h a t Juve- niles below 5 0 mm feed more actively t h a n t h e bigger size g r o u p s a n d the feeding gradually d e c r e a s e s with growth. Adults feed In coastal w a t e r s n e a r the surface.
S.guttatus: DevaraJ (1977a) reported t h a t the food of S.guttatus from Gulf of M a n n a r a n d Palk Bay consists of teleosts Sardinella spp., Ancfioutella spp., s q u i d s a n d p r a w n s .
B a s h e e r u d d l n and Nayar (1962) reported t h a t Juveniles of 4 0 - 1 2 0 mm
_ . . (CM£^
Exploited seerflsh flahery re»ource» of India - a review of t h e Madras region feed on young bony fishes, while DevaraJ (1977a) ob- served t h a t Anchoviella is the sole food of juveniles of 61-300 m m from the Gulf of M a n n a r & Palk Bay. It Is a passive predator a s compared to king seer b u t Juveniles u p to 3 0 0 mm a r e aggressive p r e d a t o r s . J u v e n i l e s feed in t h e n e a r s h o r e a r e a s w h e r e a s , a d u l t s beyond 20 m depth line. Generally larger fish do not compete with smaller fish unlike the king seer (DevaraJ, 1977a).
S.lineolatus: The s t r e a k e d seer from t h e Gulf of M a n n a r a n d Palk Bay area is known to feed exclusively on fishes s u c h as Sardinella spp., Anchoviella, Selar and Leiognathus (DevaraJ 1977a). Unlike t h e other two species, this species is found to feed more frequently on Anchoviella. J u v e n i l e s of 4 1 - 1 2 0 mm of Gulf of M a n n a r a n d Palk Bay prefer only Anchoviella s p p . Streaked seer is a m o d e r a t e predator. In the n a t u r e of predation, it resembles greatly Its cogener, t h e king seer.
Size and age at flrst maturity
DevaraJ (1983a) determined t h e length at first m a t u r i t y in S.commerson in t h e s e a s a r o u n d t h e Indian p e n i n s u l a at 7 0 1 - 8 0 0 or 750 m m (TL). DevaraJ (1987) fixed t h e minimum size a t first maturity of S. guttatus of Gulf of M a n n a r and Palk Bay a t 4 0 0 mm (TL). DevaraJ (1986b) h a s reported t h a t t h e mini- m u m size a t m a t u r i t y of S.lineolatus from the Gulf of M a n n a r and Palk Bay a s 700 mm when the age is a b o u t 2 y e a r s (Table 11).
Table 11. Maturity, spawning, sez-ratlo and fecundity details of seerfishes (Source : DevaraJ, 1983a, 1986b. 1987)
Parameters S.commerson S.guttatus S.lineolatus
1 .Size at first maturity (mm) 750 fTL) 400(TL) 700 fTL)
2.Age at first maturity 2 Years 20 Months 2 Years
S.Spawning broods in a season
4.Spawning periodicity S.Duration from
the onset of
2.27 Batches 1:1.0:27 Spawns all ova
in a month's
2.23 Batches 1:0.23:1 112 Days
2 Batches
75 Days
Marine Fisheries Research and Management maturity to first
major spawning 6. Duration between
first and second major spawning acts 7. Lunar periodicity
8. Spawning season Peak spawning Weak spawning
9. Sex-ratio (males:females) lO.Fecundity
(Absolute)
time
11.Fecundity increase per lO.mm body
length 12.Spawitog
ground
13.Study area
Inshore and protected coves Seas around the Indian penninsula
92 Days
Close to shore between 20-60 m depth
Palk Bay &
Gulf of Mannar
21 Days
No
Jem-Sep
>^r-May Jan-Feb &
Jul-Aug 52.3:43:2
•Y = -2273 +3.5793 X 291.9 million eggs/ton of spawning females 64,612
Spawning takes place around fiill-moon period Jan-Aug Apr-May Jan-Feb & Aug
39.5:60.2
•y = -1354 +3.4082 X 359.8 mUlion eggs/ton of spawning females 34,082
No
Jan-May Mid-Mar-May Jan-Mar &
Jun-Jul 40.5:59.5
•Y = -4061 +6.5928 X 570 million eggs/ton of spawning females 65,998
Inshore waters upto 25 m
Palk Bay &
GulfofMarmar
•Y = Fecundity in 1000, X = Total length in ram XL = Total length
Exploited seerflgh flghery resources of India - a review Sex ratio
The sex ratio of S.coTnmerson of 301 -1600 mm, indicated a general domi- n a n c e of m a l e s , the male to female ratio being 5 2 . 3 : 4 3 . 2 with i n d e t e r m i n a t e of 4.5%. Generally males dominated u p t o 1201-1300 mm a n d females beyond 1301 m m . The male to female ratio of S. guttatus w a s 3 9 . 5 : 60.2 with 0 . 3 % i n d e t e r m i n a t e s in 271-720 mm range. The male to female ratio, in S.Uneofatus w a s 4 0 . 5 : 5 9 . 5 In the 3 6 1 - 1 0 0 0 mm range offish.
F e c u n d i t y
Devaraj (1983a, 1986b a n d 1987) estimated fecundity a n d length rela- tionships in different maturity stages of all the three species a n d also gave a general formula for e a c h species for e s t i m a t i n g a b s o l u t e fecundity. For S.commerson the fecundity a n d length relationship is Y = - 2 2 7 3 + 3.5793 X, w h e r e Y = t h e total n u m b e r of ova in 1000s In one spawning s e a s o n a n d X = fish length (TL) in mm. He estimated t h a t a b o u t 300 million eggs are p r o - duced by every ton spawning females in a s e a s o n . For S.guttatus t h e fecun- dity a n d fish length relationship is Y = -1354 + 3.4082 X. The i n c r e a s e in egg n u m b e r per 10 mm body length is 3 4 , 0 8 2 a n d the fecundity per ton of spawn- ing females is 3 6 0 millions. The a b s o l u t e fecundity a n d fish length relation- ship for S.lineolatus is Y = -4061 + 6.5998 X. Fecundity i n c r e a s e s at t h e r a t e of 6 5 , 9 9 8 per 10 m m body length a n d t h e fecundity p e r ton of spawning-fe- m a l e s is 5 7 0 millions (Table 11).
D u r i n g 1964-81 the percentage composition of t h e king seer a n d spot- ted seer in all-India seerfish landing w a s 6 4 . 5 a n d 3 3 . 3 0 % respectively a n d a t p r e s e n t (1982-94) it is 5 4 a n d 44% respectively. The emergence of S. guttatus in t h e seerfish fishery may be a t t r i b u t e d partly due to the higher fecundity r a t e t h a n t h e king seer in addition to t h e higher effort p u t In t h e n o r t h w e s t coast of India where the spotted seer d o m i n a t e s .
Spawning ground
Devaraj (1983a) reported t h a t the spawning g r o u n d s of S.commerson are located strictly along i n s h o r e a n d protected coves like P a n a i k u l a m on Palk Bay and P u d u m a d a m on the Gulf of M a n n a r . Chacko et al. (1962) h a d also s t a t e d t h a t t h e species s p a w n s in the coastal w a t e r s . Based on t h e oc- c u r r e n c e of spawning ripe females of S.guttatus Devaraj (1987) r e p o r t e d t h a t the drift netting g r o u n d s in the Gulf of M a n n a r s o u t h of R a m e s w a r a m Island
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Marine Ftoheriei Retearch and Management
between 20 a n d 60 m depth lines form the spawning ground. In the Vizhlnjam a r e a t h e species s p a w n s close to the s h o r e a s indicated b y the occurrence of post larvae d u r i n g the breeding s e a s o n (Jones, 1962a). According to Devaraj (1986b) the streaked seer s p a w n s in the i n s h o r e w a t e r s u p t o a b o u t 2 5 m d e p t h line in the Gulf of M a n n a r and Palk Bay area.
Spawning s e a s o n
S.commerson: Based on t h e s t u d y of monthly distribution of maturity s t a g e s , DevaraJ (1983a) found t h a t S.commerson h a s a protracted spawning from a b o u t J a n u a r y to September resulting in three broods, a weak one dur- ing J a n u a r y - F e b r u a r y , a strong one d u r i n g the peak spawning in April-May a n d a n o t h e r weak brood in July-August. This view h a s ' b e e n confirmed by the occurrence of larvae a n d early Juveniles (14.4-91.8 mm length) a t Vizhlnjam in the s o u t h w e s t coast d u r i n g J a n u a r y - M a r c h (Jones, 1962a) a n d the capture of oozing males a n d partly s p e n t females in the trolling g r o u n d s off Tutlcorin d u r i n g August (Silas, 1962c). Chacko et al. (1962) have reported t h a t the species s p a w n s d u r i n g May-July in the coastal waters of M a d r a s S t a t e . The time t a k e n between the first a n d second major spawning is a b o u t 30 days a s reported by DevaraJ (1983a). There is n o l u n a r r h y t h m reported in the spawn- ing activities of the species.
S.guttatus: DevaraJ (1987) h a s shown t h a t S.guttatus also h a s an ex- tended spawning s e a s o n from J a n u a r y to August releasing a weak brood in J a n u a r y - F e b r u a r y , a strong brood in March-July with a peak in April-May and a weak brood in August. This h a s been further supported by J o n e s (1962a) who collected large n u m b e r s of late p o s t larval a n d Juvenile specimens of the species from Vizhlnjam a r e a d u r i n g February-May. Krlshnamoorthl (1958) recorded high percentage of m a t u r i n g fishes In the Gulf of M a n n a r and Palk Bay a r e a during March-October a n d ripe specimens d u r i n g May-July. Spawn- ing t a k e s place a r o u n d t h e fullmoon period a n d it t a k e s a b o u t 112 days from the o n s e t of m a t u r i t y to spawning and a b o u t 92 days between t h e two major s p a w n i n g s .
S.lineolatus: DevaraJ (1986b) observed t h a t streaked seer in the Gulf of M a n n a r a n d Palk Bay s p a w n s .during J a n u a r y t h r o u g h May. Broods are released In three b a t c h e s , a weak one in J a n u a r y to early March, a strong one in mid March to end of May a n d a n o t h e r weak brood in late J u n e to late J u l y . The time t a k e n from the o n s e t of m a t u r i t y to the major spawning is 7 5 days
Exploited aeerflgh fishery resources of India - a review a n d b e t w e e n t h e first a n d second major s p a w n i n g a b o u t 2 1 d a y s . As in S.commerson there is no l u n a r periodicity in t h i s species also.
Spawning p e r i o d i c i t y
S.commerson: Devaraj (1983a) h a s reported trimodal distribution of ova in the ripe ovaries of S.com.merson a n d concluded t h a t t h e species spawn in 2.27 b a t c h e s in the ratios of 1:1:0.27 at a n interval of a m o n t h or even less in each spawning s e a s o n (Table 11). Munro (1942) observed three distinct size groups in t h e ripe ovaries of king seer from n o r t h Q u e e n s l a n d . Lewis et al.
(1974) reported two well defined b a t c h e s of ova and a n o t h e r b a t c h of smaller ova in a ripe ovary of S.commerson from New Guinea.
S.guttatus: Based on the multiplicity of modal size g r o u p s of ova in t h e advanced m a t u r i n g a n d ripe ovaries of S.guttatus, Devaraj (1987) reported t h a t t h i s species also s p a w n s more t h a n once i.e., in 2 . 2 3 b a t c h e s in each s e a s o n in t h e ratios of 1:0.23:1 (Table 11). De J o n g (1940) observed three modes of m a t u r i n g ova in the ova diameter frequency polygons for t h e tennigiri (S.guttatus) from J a v a Seas a n d p r e s u m e d t h a t all t h e three b a t c h e s might be discharged successively. Krishnamoorthi (1958) observed two g r o u p s of ova of i m m a t u r e a n d m a t u r e in the ova diameter frequency of m a t u r i n g S.guttatus from Gulf of M a n n a r a n d Palk Bay. In t h e a b s e n c e of i n t e r m e d i a t e g r o u p s of ova h e concluded t h a t t h e species s p a w n s in a very s h o r t a n d restricted pe- riod. However, t h e observations m a d e by h i m a r e viewed a s u n t e n a b l e by Devaraj (1987) a s only " m e a s u r e m e n t s of t h e d i a m e t e r s of eggs in ovaries well Eidvanced toward spawning may give evidence of d u r a t i o n of s p a w n i n g in a fish (Hickling a n d Rutenberg, 1936)".
S.Uneolatus : According to Devaraj (1986b) the m a t u r e a n d advanced ripe ovaries of S.lineolatus showed bimodal distribution of ova a n d t h e ova released in two successive b a t c h e s in each spawning season. Except the s t u d - ies by Devaraj (1986b) there is virtually no s t u d y on t h e reproductive biology of t h e species from anywhere in t h e world. The reason is d u e to its scarce occurrence in t h e fishery, though it h a s a wide distributional r a n g e in the Indo-Malaya archipelago (Devaraj, 1986b).
Population d y n a m i c s
The earliest study on the population dynamics of seerfishes w a s by Devaraj (1977a, 1983b). He estimated t h e stock a s s e s s m e n t p a r a m e t e r s of all the t h r e e species, S.commerson, S.guttatus a n d S.lineolatus. Later Kasim a n d
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Marine Fisheries Research and Management
H a m s a (1989) s t u d i e d the p o p u l a t i o n d y n a m i c s of S.commerson from the Tuticorin waters, Pillai et al. (1994) from Kerala a n d K a r n a t a k a coasts a n d Y o h a n n a n et al. (1992) from Tamil Nadu and Kerala w a t e r s .
S.commerson : The total mortality coefficient (Z), the n a t u r a l mortality coefficient (M), the fishing mortality coefficient (F) a n d other stock a s s e s s - m e n t p a r a m e t e r s like the exploitation ratio (E), the exploitation r a t e (U), the length a t first c a p t u r e (Ic) a n d t h e age at first c a p t u r e (tc) were estimated by different a u t h o r s for S.commerson from different regions. Most of the esti- m a t e s on the species were b a s e d on drift gillnet fishery.
The e s t i m a t e s of Z for the drift gillnet fishery ranged from 0.81 for west coast to 4.08 for Kerala d u r i n g different periods. The recent e s t i m a t e s of Z reported by Yohannan et al. (1992) and Pillai etal. (1994) are higher (3.09-4.08) t h a n the earlier estimates (0.81-1.28) of DevaraJ (1983b) and Kasim and Hamsa (1989). DevaraJ {1983b) h a s observed a n increasing trend in t h e values of Z (0.4 for Cape Comorin, 0.53 for Kerala, 0.71 for K a r n a t a k a , 1 for M a h a r a s h t r a a n d 1.13 for Gujarat) a n d indicated the possibility of a northerly migration a n d opined t h a t Z for any locality in t h e migratory route is the cumulative Z comprising t h e Z for t h e locality in question plus for all a r e a s s o u t h of it.
Kasim a n d H a m s a (1989) also estimated Z for S.commerson exploited by other gears also, hooks & lines, 'podivalaV a n d trawl at 0 . 8 3 , 2 . 2 3 and 2.49 respec- tively.
The M e s t i m a t e s for S.commerson ranged from 0.37 (Kasim and Hamsa, 1989) to 0.78 (Yohannan et al. 1992 and Pillai et al. 1994). DevaraJ (1983b) estimated M for the Gulf of M a n n a r and Palk Bay stock following the regres- sion of effort on Z a s 0.4. Kasim a n d H a m s a (1989) calculated the values at 0.43 in 'paruvalai', 0.37 in hooks & line, 0.55 in 'podivalai' and 0.57 in trawlnet with an average of 0.48 by the above method. They also estimated M inde- pendently following Pauly's (1980) method at 0.45. Yohannan et al. (1992) and Pillai et al. (1994) determined M employing the equation of Pauly. As seen in the total mortality values, the recent estimations by Pillai et al. (1994) and Yohannan et al. (1992) are higher. Devaraj {1983b) also estimated M values for spotted seer a s 0.40, for male streaked seer as 0.42 a n d for female streaked seer as 0.34.
The fishing mortality coefficient r a t e s in drift gillnet fishery for king
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Exploited geerflsh fishery resources of India - a review seer varied Irom 0.67 for Gulf of M a n n a r during 1967-74 to 3.30 for Kerala d u r i n g 1984-88 indicating a n Increasing trend in t h e fishing mortality r a t e s similar to n a t u r a l mortality r a t e s d u r i n g the r e c e n t y e a r s . The fishing mor- tality coefficient at Tuticorln among the four gears varied from 0.47 for h o o k s
& line to 1.97 In trawl.
The exploitation ratio for king seer in different fisheries in different regions indicate t h a t the E in glUnet fishery ranged from 0.51 (Devaraj, 1983b) for west coast during 1969-74 to 0.81 (Yohannan et al 1992) for Kerala dur- ing 1984-88. It Is evident t h a t the exploitation level in r e c e n t t i m e s h a s in- creased along the Tamil Nadu, Kerala and K a r n a t a k a coast. Y o h a n n a n et al.
(1992) estimated the p r e s e n t E value a s 0.81 a n d 0.71 a s a g a i n s t the E m a x of 0.58 a n d 0.60 a t M/K ratio of 1 and 1.5 respectively. Similarly for Tamil Nadu t h e p r e s e n t E v a l u e s are 0.75 a n d 0.62 a s against E m a x of 0.52 each a t M/K 1 a n d 1.5. Based on t h i s they inferred t h a t the exploitation ratio is above MSY level a n d advocated for reduction in the e x p e n d i t u r e of effort.
According to them, for all India level, a 16% reduction In the exploitation r a t e would be needed to bring the fishery back to MSY level.
At Tuticorln among the four gears for king seer fishery, t h e E varied from 0.57 In hook & line to 0.84 in 'podivalai' showing higher fishing p r e s - s u r e by all the three gears except hook & line.
Devaraj (1983b), Kasim and H a m s a (1989) a n d Y o h a n n a n et al (1992) made the yield per recruit s t u d i e s on S.commerson. By the c o n s t r u c t i o n of yield Isopleth diagram the maximum yield for different v a l u e s of tc keeping F c o n s t a n t a n d t h e MSY for different values of F keeping tc c o n s t a n t have been studied by them. It showed t h a t the optimum age of exploitation (ty) is 4.21 y e a r s a t a potential yield Y' of 2 3 3 9 g for king seer In the Indian Seas (Devaraj, 1983b) and 3.88 y e a r s and 1749 g for the Tuticorln stocks (Kaslm a n d H a m s a , 1989). Y o h a n n a n et al. (1992) estimated the optimum size (Ic) a s 876 mm for Kerala a n d 803 mm for Tamil Nadu against the p r e s e n t Ic of 600 m m a n d 450 mm respectively. In the king seer fishery at Tuticorln it h a s been shown t h a t t h e F m a x which c a n produce the Ymax h a s n o t exceeded 0.5 for any of t h e four gears b u t the p r e s e n t Fs are well above 0.5 except hook & line confirming the existence of higher effort I n p u t by the o t h e r t h r e e g e a r s , 'paruvalai',
'podivalai' and trawl.
Marine Figherieg Research and Management
S.guttatus: The M was estimated at 0.40. The values of Z, F. E, and U were higher, 1.83, 1.43. 0.78 and 0.65 respectively for Gulf of M a n n a r as compared to east coast excluding Palk Bay and the Gulf of M a n n a r (0.69, 0.29, 0.42 a n d 0.21), Palk bay (0.84, 0.44, 0.52 a n d 0.30) a n d west coast (0.74, 0.34, 0.46 and 0.24} Indicating t h a t the species was over exploited along the Gulf of M a n n a r coast during the period 1964-74 (Devaraj, 1977a).
In the a b s e n c e of similar s t u d i e s In the r e c e n t years there is a gap in our knowledge on the p r e s e n t exploitation level of the species.
For spotted seer of Gulf of M a n n a r the optimum age of exploitation Is found to be 4.14 years at the optimum yield per recruit of 547 g (Devaraj,
1983b).
S.lineolatus: Stock a s s e s s m e n t p a r a m e t e r s for males a n d females of S.lineolatus were d e t e r m i n e d for different regions for 1 9 6 4 - 7 4 period by Devaraj, 1977a. The M was estimated as 0.42 for males and 0.34 for females.
The Z a n d F were high for both sexes (2.61 and 2.19 for males and 2.83 and 2.49 for females) for Palk Bay a n d lowest (1.08 and 0.66 for males a n d 1.08 and 0.74 for females) for west coast. The exploitation ratios a n d the exploita- t i o n r a t e s w e r e a l s o h i g h (E= 0 . 6 1 - 0 . 8 4 , U= 0 . 4 0 - 0 . 7 8 for m a l e s a n d E=0.69-0.88, U= 0 . 4 6 - 0 . 8 3 for femlaes) for b o t h sexes from all regions Indi- cating t h a t the species w a s u n d e r heavy fishing p r e s s u r e during the above period. For this species also, there Is no s t u d y on the stock a s s e s s m e n t pa- r a m e t e r s In t h e recent y e a r s .
S t o c k a s s e s s m e n t
Devaraj (1986a) estimated the all-India m a x i m u m s u s t a i n a b l e yield (MSY) of seerflshes b a s e d on the catch a n d effort d a t a for 1958-67 a t 15,958 t a t an a n n u a l effort of a b o u t 2.2 million drift glllnet boat days. But this e s t i m a t e Is proved to be unrealistic due to the fact t h a t the average a n n u a l catch obtained during 1964-81 was 17,852 t a t a m u c h less effort of 1.03 million boat days. The c u r r e n t a n n u a l catch of 3 8 , 3 9 4 t (1990-94) also con- firms t h e above e s t i m a t e a s an unrealistic one.
The recent regionwise MSY estimates given by Devaraj (1986a) and the p r e s e n t yield are given in Table 12. It Is evident t h a t t h o u g h t h e p r e s e n t all-India yield of 3 8 , 0 0 0 t Is nearly close to MSY (40,000 t), the c u r r e n t pro-
