MATURATION and SPAWNING of the SMALLSPOTTED GRUNT Pomadasys Commersonnii (LACEPÈDE, 1801) in the ARABIAN SEA OFF OMAN

Thalassas, 27 (1): 67-79 An International Journal of Marine Sciences

MATURATION AND SPAWNING OF THE SMALLSPOTTED GRUNT Pomadasys commersonnii (LACEPÈDE, 1801) IN THE ARABIAN SEA OFF OMAN

A. AL-NAHDI, A. AL-MARZOUQI, N. JAYABALAN(1) & S. AL-HABSI

Key words: Pomadasys commersonnii, Lm, GSI, relative condition, spawning, fecundity, sex-ratio, Arabian Sea, Oman

ABSTRACT INTRODUCTION

Observations on the maturation and spawning Fishes of the genus Pomadasys (Family: of the smallspotted grunt Pomadasys commersonnii Haemulidae) are represented by 11 species in caught from the Arabian Sea off Oman were made Omani waters (Fouda et al., 1997). The species between April 2005 and March 2007. While, males P. commersonnii popularly called smallspotted matured (50% maturity) at 44.2 cm TL, females grunt is one of the commonest fishes caught by matured at 42 cm TL. The population of P. the artisanal and industrial trawlers from Omani commersonnii spawned during June-December. The waters. The species is distributed along the northwest monthly gonado-somatic indices and the occurrence coast of India to the southern Oman, in the south of spent gonads coincided with the peak spawning to Seychelles, Madagascar and South Africa in the season. However, the monthly relative condition was coastal waters, estuaries, tidal fissures and even can not indicative of the spawning activity. Individual fish tolerate fresh water (Smith and Heemstra, 1986). spawned more than once a year. Fecundity ranged Besides forming a good recreational fishery (Smith from 214,510 to 1,421,520 eggs. Sex-ratio indicated and McKay, 1986; Mann et al., 2002), the species has homogeneous distribution of males and females in also been identified as a potent candidate for intensive the population. marine fish farming in South Africa (Deacon and Hecht, 1995; Mperdempes and Hecht, 2002).

The estimated contribution of P. commersonnii Marine Science and Fisheries Centre from the Arabian Sea coast of Oman for the years Ministry of Fisheries Wealth, P.O. Box 427; P.C. 100, Muscat Sultanate of Oman 2005-2006 and 2006-2007 stood at 507 t and (1)E-mail: [email protected] 443 t respectively (GoSO, 2005; 2006; MSFC,

67 A. AL-NAHDI, A. AL-MARZOUQI, N. JAYABALAN & S. AL-HABSI

Figure 1: Map showing the sampling locations. unpub. data). In spite of its commercial and culture gillnet, trap and handlines landed at Lakbi and based fisheries importance of P. commersonnii, Salalah operated in the coastal waters of the Arabian no information is available on the biology and Sea along the coast of Oman (Fig. 1). Altogether, population characteristics from Omani waters. 838 specimens of P. commersonnii were used for the The present paper deals with the maturation and study. The fish were brought to the laboratory in ice spawning of P. commersonnii from the Arabian Sea boxes and after washing, each fish was measured coast of Oman. to its total length (TL) to the nearest 1 mm using a fish measuring board and the total wet weight (TW) MATERIAL AND METHODS was recorded to the nearest 1 g using an electronic balance. Then the fish was cut open and the sex Sampling protocol and maturity stage were recorded. The gonads were removed and weighed to the nearest 0.001 g using Monthly random samples of fish were obtained an electronic balance. Ovaries were preserved in between April 2005 and March 2007 from the 5% neutral formalin for subsequent analyses of commercial catches of the artisanal gears such as maturation and spawning.

68 MATURATION AND SPAWNING OF THE SMALLSPOTTED GRUNT Pomadasys commersonnii (LACEPÈDE, 1801) IN THE ARABIAN SEA OFF OMAN

Maturation and spawning

Maturity stages

The female maturity stages were fixed by macroscopic observation of ovaries and by

the microscopic structure of the eggs. The male

maturity stages were determined by macroscopic

structure of testes in the body cavity. Six stages of maturity (I-Immature; II-Maturing 1; III-Maturing 2; IV-Mature; V-Ripe/Running and VI-Spent) were recognized in females and males.

Development of ova to maturity

A total of 36 ovaries from various stages excepting stage V were used for measurement of intraovarian eggs. The development of ova from immature to mature/ripe was studied by measuring the intraovarian eggs using an ocular micrometer

fitted to the eye piece of the microscope. Each

ocular micrometer division (m.d.) was equal to 12μ.

The method of measurement of ova diameters was similar to that of Clark (1934); Prabhu (1956) and Jayabalan (1986). Ova diameters from ovaries of same stage of maturity were pooled and used for percentage frequency curves. Ova were grouped into 2 ocular micrometer divisions (m.d.) size groups. Except in stage I, immature ova less than 5 m.d. were not measured in other maturity stages as they occurred in large numbers indicating the general egg stock.

Length at first maturity

To calculate the length at first maturity (Lm),

fish were grouped sex-wise into 2 cm class intervals and fish from stage III onwards were considered as mature. A logistic function was fitted to the fraction of mature fish against length interval using the non- linear least square regression method as suggested by King (1995). The logistic equation used was:

Figure 2: Development of ova to maturity in P. commersonnii. P = 100 / (1 + exp (-r (L-Lm)))

69 A. AL-NAHDI, A. AL-MARZOUQI, N. JAYABALAN & S. AL-HABSI

6 GSI 4

0 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Months

Figure 3: Monthly gonado-somatic indices (mean and SD) in male P. commersonnii.

GSI 4

0 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar

Months

Figure 4: Monthly gonado-somatic indices (mean and SD) in female P. commersonnii.

2,5

Kn 1,5

0,5 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar

Months Figure 5: Monthly relative condition (mean and SD) in male P. commersonnii.

70 MATURATION AND SPAWNING OF THE SMALLSPOTTED GRUNT Pomadasys commersonnii (LACEPÈDE, 1801) IN THE ARABIAN SEA OFF OMAN

2,5

Kn 1,5

0,5 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar

Months

Figure 6: Monthly relative condition (mean and SD) in female P. commersonnii.

100

Ƒ Female 60 Lm = 42 cm

¨ Male ------40 Lm = 44.2 cm % maturity

0 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80

Total length (cm)

Figure 7: Length at first maturity in P. commersonnii. where GSI = GW/TW x 100 where GW is the gonad P = percent mature fish in length class L, weight and TW the total weight of fish. r = the width of the maturity curve and Lm = length at 50% maturity The monthly mean and standard deviation (SD) were estimated. Gonado-somatic Index Relative condition factor (kn) The monthly gonado-somatic index (GSI) was calculated separately for males and females for the The monthly relative condition factor (Kn) was pooled data of two years using the formula, estimated by pooling the data of 2005-06 and 2006-

71 A. AL-NAHDI, A. AL-MARZOUQI, N. JAYABALAN & S. AL-HABSI

Figure 8: Distribution of monthly maturity stages of P. commersonnii (2005-06 & 2006-07 pooled).

72 MATURATION AND SPAWNING OF THE SMALLSPOTTED GRUNT Pomadasys commersonnii (LACEPÈDE, 1801) IN THE ARABIAN SEA OFF OMAN

07 to understand the condition of the fish following (F) were estimated by linear regression analysis based Le Cren (1951) as, on the equation, Log F = Log a +b Log X Kn = TW/aLb where TW = observed weight, aLb = calculated weight obtained from the length-weight Sex-ratio relationship. The monthly sex-ratio was estimated (male to Occurrence of maturity stages of gonads female) for 2005-06 and 2006-07. The monthly and annual sex-ratios were tested for the expected ratio of To determine the spawning season in the 1:1 by chi-square (X 2) analysis. species, occurrence of different maturity stages of males and females were estimated separately RESULTS AND DISCUSSION for various months of 2005-06 and 2006-07. Then the monthly data of maturity stages for both Maturation and spawning the years were pooled sex-wise and the average percentage occurrence of different maturity stages Maturity stages was calculated and plotted. Six stages of maturity (I-Immature; II-Maturing Spawning frequency 1; III-Maturing 2; IV-Mature; V-Ripe/Running and VI-Spent) could be established in both males and The spawning frequency in individual P. females of P. commersonnii (Table- 1). Microscopic commersonnii was determined based on the mature observation of ova in different stages of ovaries could and maturing modes of intraovarian eggs in advanced be clearly differentiated into immature, maturing stages of maturity. and mature ova. No male or female fish with stage V gonad occurred in the commercial catches during the Fecundity period of present study.

Fecundity (F) was estimated gravimetrically from Development of ova to maturity 20 ovaries of stage IV preserved in ‘modified Gilson’s fluid’ (Bagenal and Brawn, 1971). A small portion of The intraovarian egg development from immature the ovary was removed and weighed to the nearest to mature stage was studied in all the stages of ovaries 0.001g in an electronic microbalance. The piece of excepting stage V (Fig. 2). In stage I ovary, the ova the ovary was taken to a counting chamber and all the measured from 1-2 m.d. to 8 m.d. (1-2 and 3-4 m.d. mature eggs in the piece of the ovary were counted size groups). This immature group of ova formed under a binocular microscope. From the number of the general egg stock from which a group of ova mature ova in the piece of the ovary, the total number got separated for further development. In stage II, a of mature ova was estimated using the formula, batch of ova formed a mode at 13-14 m.d. with few ova measured up to 15-16 m.d. besides the immature F = (TW of the ovary) / (Weight of the sample)*Number group of ova. of mature ova in the sample. In stage III, the ova forming mode at 13-14 The relationships between total length of fish m.d. in stage II shifted to 23-24 m.d. and few larger (TL) and fecundity (F), total weight of fish (TW) and ova measured up to 29-30 m.d. The ova forming fecundity (F) and ovary weight (OW) and fecundity secondary modes in stages II and III were the

73 A. AL-NAHDI, A. AL-MARZOUQI, N. JAYABALAN & S. AL-HABSI

y = 2,434x + 1,337 6,2 R² = 0,529 A

5,8

5,6 Log fecundity Log 5,4

5,2 1,7 1,75 1,8 1,85 1,9 1,95

Log length

6,2 y = 0,944x + 2,496 R² = 0,526 B 6

5,8

5,6 Log fecundity Log 5,4

5,2 3,1 3,2 3,3 3,4 3,5 3,6 3,7

Log body weight

6,4 C 6,2 y = 0,982x + 3,758 R² = 0,950 6

5,8

5,6 Log fecundilty Log 5,4

5,2 1,5 1,7 1,9 2,1 2,3 2,5 2,7

Log ovary weight

Figure 9: Fecundity in relation to (A) total length (B) body weight and (C) ovary weight of P. commersonnii. maturing groups of eggs. In stage IV, besides a group 39-40 m.d. In stage VI ovary, the ova forming mode of ova forming mode at 23-24 m.d., another batch at 23-24 m.d. was persistent after the larger group of of eggs clearly separated from it formed a mode at ova were released during spawning and remnant of 35-36 m.d. In this stage the larger ova measured up to disintegrating larger ova were seen.

74 MATURATION AND SPAWNING OF THE SMALLSPOTTED GRUNT Pomadasys commersonnii (LACEPÈDE, 1801) IN THE ARABIAN SEA OFF OMAN

Table 1: Classification of maturity stages in P. commersonnii.

Stage of maturity Male Female Position of last mode Nature and extent of ovary in Appearance of ova under and maximum diameter Nature and extent of body cavity microscope of ova (in parentheses) testis in body cavity in m.d. I Immature Small, transparent, Small, transparent, pale, Irregular, small, 1-2 (8) pale, occupying a very occupying a very small yolkless/yolk deposit just small portion to 1/3 of portion to 1/3 of body cavity, started, transparent with body cavity ova not visible to naked eye clearly visible/partially visible nucleus II Maturing 1 Whitish, translucent, Pale yellow, granular ova Medium sized, assume round 13-14 (18) occupying about 1/2 of visible to naked eye, shape, opaque, with fair body cavity occupying about 1/2 of body amount of yolk cavity III Maturing 2 Creamy white, occupy Pale yellowish, blood vessels Medium sized, opaque, fully 23-24 (30) about 3/4 of body visible on dorsal side, ova yolked cavity clearly visible, occupying about 3/4 of body cavity IV Mature Creamy white, soft, Pinkish yellow, blood vessels Large sized, mature, 35-36 (40) occupying about full prominent, large ova transparent at periphery length of body cavity prominently visible, occupying about full length of body cavity V Ripe/Running Not encountered Not encountered - - VI Spent Flabby, little reddish, Flaccid, reddish, occupying Medium sized ova present 23-24 (-) occupying about 1/2 of about 1/2 of body cavity with disintegrating ripe ova body cavity.

Gonado-somatic Index As the values fluctuated narrowly, it was not possible to relate them to spawning activity. The monthly gonado-somatic indices in males (Fig. 3) and females (Fig. 4) of P. commersonnii Length at first maturity pooled for 2005-2006 and 2006-2007 indicated that during certain months, (July, September, January- Females measuring up to 22 cm TL were all March) the indices were higher in males than in immature; whereas, first mature male was recorded females. While, the monthly GSI values of males at 24 cm TL. While the first spent male was recorded ranged from 0.4 to 4.6, in females the range was at 54.5 cm, the first spent female measured 49.1 between 0.7 and 5.5. Generally, the values were cm. In both males and females, the percentage of higher in both males and females between July and mature fish increased with the increase in fish length. November indicating the availability of more number The length at which 50% of maturity (Lm) of P. of mature fish in the commercial catches. The above commersonnii was estimated at 44.2 cm for male and period coincided with the peak spawning season (see 42 cm for female (Fig. 7) indicating females to mature section on Spawning season). slightly at an earlier length than males. However, in the South African waters, males and females of P. Relative condition factor (Kn) commersonnii matured at the average length of 32 cm TL and 38 cm CL respectively (van der Elst and The monthly Kn value was always higher in males Adkin, 1991). than in females (Figs. 5 & 6) indicating that the males were comparatively in better condition than females. Though, female maturing earlier than male in the The Kn values ranged from 1.33 (May) to 1.71 (June) present study is a deviation from the earlier report in males and from 1.18 (May) to1.63 (June) in females. (van der Elst and Adkin, 1991); it is not uncommon

75 A. AL-NAHDI, A. AL-MARZOUQI, N. JAYABALAN & S. AL-HABSI

Table 2: Fecundity in P. commersonnii.

S.No. Length (cm) Total wt (g) Ovary wt (g) Fecundity 1 53.7 1644 42.9 214510 2 54 1748 53.08 268054 3 54.1 1725 104.47 511903 4 54.2 1860 66.37 301983 5 54.6 1852 95.95 477831 6 54.7 1892 91.67 481266 7 55.6 1754 82.33 504679 8 55.6 1817 84.82 445305 9 57.7 2024 84.79 487543 10 62.1 2466 119.8 694840 11 66.5 2840 80.59 402950 12 67 3199 85.75 398738 13 69 3460 85.7 458495 14 70.3 3698 144.82 767546 15 71.2 3557 106.93 557105 16 71.7 3873 168.14 894505 17 72 3423 81.24 495564 18 72.5 3249 90.06 630420 19 78.4 4511 256.26 1281300 20 78.5 4372 296.15 1421520

that in several species of demersal fishes from the these months (Fig. 8). From January to April, the fish Arabian Sea and Arabian Gulf, maturity in females occurred with gonad stages of I-IV. earlier than in males has been reported (El-Sayed and Bary, 1994; McIlwain et al., 2006; Al-Marzouqi et In the Indian Ocean region, several species of al., 2009). fishes spawn for 7-9 months in a year (Qasim, 1973) and in the Arabian Sea off Oman, some sparids spawn Most tropical marine fishes mature early at the during the SW monsoon period coinciding with the age of first or second year of their life (Qasim, 1973). drop in temperature of the seawater and increase The age estimations of P. commersonnii showed the in primary productivity (McIlwain et al., 2006). females maturing at the end of second year and males Though, the mature gonads (stage IV) occurred maturing at the earlier part of third year of their life in throughout the year, spawning appeared to take Omani waters (Al-Marzouqi et al., 2009). place during both southwest and northeast monsoon periods. This might be due to food availability and Spawning season better survival (Qasim, 1973). The higher values of GSI (Figs. 3 & 4) in both males and females The spawning season of P. commersonnii in the coincided well with the spawning season. However, Arabian Sea off Oman appeared to extend from June the monthly Kn values could not be related to the to December as mature/spent gonads occurred during spawning activity in the fish.

76 MATURATION AND SPAWNING OF THE SMALLSPOTTED GRUNT Pomadasys commersonnii (LACEPÈDE, 1801) IN THE ARABIAN SEA OFF OMAN

Table 3: Monthly sex-ratio in P. commersonnii during 2005-06

Month Total No. No. of No. of Male: Chi-square fish males Females Female value April 05 55 24 31 1:1.29 0.89 May 22 8 14 1:1.75 1.63 June 28 13 15 1:1.15 0.14 July 27 17 10 1:0.58 1.81 August 80 46 34 1:0.74 1.8 September 48 24 24 1:1 0 October 41 17 24 1:1.4 1.19 November 14 6 8 1:1.33 0.28 December 49 30 19 1:0.63 2.47 January 06 12 4 8 1:2 1.33 February 24 12 12 1:1 0 March 25 10 15 1:1.5 1 Total 425 211 214 1:1. 01 0.02

Spawning frequency (R2 = 0.9501) than the relations between the TL of fish (L) and fecundity (F) and total weight of fish The mature ovary (stage IV) of P. commersonnii (W) and fecundity (F). The estimated fecundity of P. possessed clearly separated maturing (mode at 23-24 commersonnii ranged from 214,510 to 1,421,520 eggs. m.d.) and mature (35-36 m.d.) groups of ova (Fig. 2). In the spent ovary (stage VI), while the maturing The logarithmic relationship between the group of eggs was present, the mature group of fecundity (F) and length of fish (L) (Fig. 9A) can be eggs was absent indicating that the mature ova were expressed by the equation, shed during spawning. As the maturing group of Log F = 1.3375 + 2.4347 log L (R2 = 0 . 0 . 5 2 9 6 ) ova had completed half the maturation process than The relationship between fecundity (F) and body the immature group of eggs, it would require only weight (W) (Fig. 9B) was found to be, about half the time to become mature/ripe and to Log F = 2.4969 + 0.9444 log w (R2 = 0 . 0 . 5 2 6 3 ) be spawned (Prabhu, 1956). Hence, it appears that The relationship between fecundity (F) and ovary individual P. commersonnii may spawn for the second weight (OW) (Fig. 9C) was estimated as, time in a year in the Arabian Sea. Log F = 3.7583 + 0.9826 log OW (R2 = 0 . 0 . 9 5 0 1 )

The size frequency analysis of fish in the Sex-ratio commercial catches during the period of study showed that individuals only about 18% of individuals During 2005-2006, no significant difference in the caught were <44.2 cm TL (Al-Marzouqi et al., 2009; monthly sex-ratio was observed (Table- 3). Similarly, Jayabalan et al., MS) This indicated that more than the monthly sex-ratios did not differ significantly 80% of the adult fish had the opportunity to spawn in during 2006-2007 except during October 2006 (chi- the Omani waters. square value = 6.9) (Table- 4).

Fecundity The overall annual sex-ratios for 2005-2006 (chi- square value = 0.02) and 2006-2007 did not differ The length, total weight and weight of the ovary of significantly (chi-square value = 2.64). Hence, the fish considered and the estimated fecundity are given distribution of males and females was homogeneous in Table- 2. The relation between the ovary weight in the population of P. commersonnii. Similar (OW) and fecundity (F) could be better correlated observation in the related species P. incisus from the

77 A. AL-NAHDI, A. AL-MARZOUQI, N. JAYABALAN & S. AL-HABSI

Table 4: Monthly sex-ratio in P. commersonnii during 2006-07

Month Total No. No. of No. of Male: Chi-square fish males Females Female value April 06 15 6 9 1:1.50 0.6 May 51 31 20 1:0.65 2.4 June 22 7 15 1:2.14 2.9 July 55 25 30 1:1.20 0.46 August 49 30 19 1:0.63 2.46 September 25 12 13 1:1.08 0.04 October 58 39 19 1:0.49 6.9* November 24 11 13 1:1.18 0.17 December 28 17 11 1:0.65 1.28 January 07 27 12 15 1:1.25 0.34 February 39 23 16 1:0.70 1.26 March 20 10 10 1:1 0 Total 413 223 190 1:0.85 2.64 * Significant at 5% level

Canarian Archipelago has been reported (Pajuelo et acknowledged. We are also thankful to our colleagues al., 2003). in the Marine Science and Fisheries Centre and the Fisheries Laboratory at Salalah for their help. Based on the varied spawning habits of teleost fishes, they could be grouped into four categories REFERENCES (Hickling and Ruternberg, 1936; James, 1967). While, group I fishes spawn only once a year for shorter Al-Marzouqi A, Jayabalan N, Al-Nahdi A, Al-Habsi S duration, group II fishes have long duration of (2009). Biology, stock assessment and management of spawning but once a year, group III fishes spawn six species of demersal fishes from the Arabian Sea more than once a year and group IV fishes have coast of Oman. Demersal Fisheries Project II Final intermittent spawning throughout the year. Several Report. Ministry of Fisheries Wealth, Oman, 240 pp. species of fishes in the tropical seas spawn more than Bagenal TB, Brawn E (1971). Eggs and early life history. once a year (Prabhu, 1956; Jayabalan, 1986; Zacharia In: Methods for assessment of fish production in fres- and Jayabalan, 2007). The species P. commersonnii hwaters. Ricker W.E. (ed.), Blackwell Sci. Publ. Oxford, may be grouped under category III as they spawn 166-168 p. more than once. As the size range of mature group Clark FN (1934). Maturity of California sardine (Sardinella of ova forming mode at 35-36 m.d. is narrow and this caerulea) determined by ova diameter measurements. batch had been clearly separated from the maturing Fish. Bull. 42: 1-49. group of ova, individual fish may spawn for shorter Decon N, Hecht T (1995). Observations on the ther- duration (Prabhu, 1956; James, 1967; Jayabalan, 1988; moregulatory behaviour of juvenile spotted grunter, Zacharia and Jayabalan, 2007). Pomadasys commersonnii (Haemulidae: Pisces). J. Appl. Ichthyol. 11: 100-110. ACKNOWLEDGEMENTS El-Sayed AM, Barry KA (1994). Life cycle and fecundity of rabbitfish Siganus canaliculatus (Teleosti: Siganidae) We are thankful to H.E. Dr. Hamed Al-Oufi, in the Arabian Gulf. Obelia 20: 79-88. the Under-secretary, Ministry of Fisheries Wealth, Fouda MM, Hermosa Jr GV, Al-Harthi SM (1997). Status of Government of Sultanate of Oman, for his encourage- fish biodiversity in the Sultanate of Oman. Convention ment and valuable suggestions. The financial support on Biological Diversity. First National Report, from the Agriculture and Fisheries Development Directorate-General of Nature Reserves, Sultanate of Fund, Government of Sultanate of Oman is gratefully Oman. 19+21 pp.

78 MATURATION AND SPAWNING OF THE SMALLSPOTTED GRUNT Pomadasys commersonnii (LACEPÈDE, 1801) IN THE ARABIAN SEA OFF OMAN

GoSO (Government of Sultanate of Oman), (2005). Fisheries Van der Elst RP, Adkin F. (eds) (1991). Marine linefish: Statistics Book 2005. Sultanate of Oman. priority species and research objectives in southern GoSO (Government of Sultanate of Oman), (2006). Fisheries Africa. Oceanogr. Res. Inst. Spec. Publ. No. 1, 132 pp. Statistics Book 2006. Sultanate of Oman. Zacharia PU, Jayabalan N (2007). Maturation and spaw- Hickling CF, Ruternberg E (1936). Ovary as an indicator of ning of the whitefish, Lactarius lactarius (Bloch the spawning in fishes. J. mar. biol. Ass. U.K. 21: 311-317. and Schneider, 1801) (Family Lactariidae) along the James PSBR (1967). The ribbon-fishes of the family Karnataka coast, India. J. Mar. Biol. Ass. India 49(2): Trichiuridae of India. Memoir 1, Marine Biol. Ass. 166-176. India, 226 pp. Jayabalan N (1986). Reproductive biology of the silverbelly (Received: July, 27, 2010; Accepted: October, 23, 2010) Leiognathus splendens (Cuvier) at Porto Novo. Indian J. Fish. 33(2): 171-179. Jayabalan N (1988). Reproductive biology of the ponyfish, Gazza minuta (Bloch) from Porto Novo, East coast of India. Indian J. Mar. Sci. 17: 51-54. King M (1995). Fishery biology: assessment and management. Fishing News Books, Blackwell Science Limited. Le Cren CD (1951). The length-weight relationship and sea- sonal cycle in gonad weights and conditions in the perch (Perca fluviatilis). J. Anim. Ecol. 20: 201-219 Mann BQ, James NC, Beckley LE (2002). An assessment of recreational fishery in the St. Lucia estuarine system, Kwazulu-Natal, South Africa. S. Afr. J. Mar. Sci. 24: 263-279. McIlwain J, Hermosa GV, Claereboudt M, Al-Oufi HS, Al-Awi M (2006). Spawning and reproductive patterns of six exploited finfish species from the Arabian Sea, Sultanate of Oman. J. Appl. Ichthyol. 22: 167-176. Mperdempes A, Hecht T (2002). Cage and tank culture of dusky kob, Argyrosomus japonicus and spotted grunter, Pomadasys commersonnii. Southern African Marine Science Symposium (SAMSS 2002): Currents, Coasts Communities, vp. 2002 Abstract. Pajuelo JE, Lorenzo JM, Gregoire M, Dominiguez-Seoane R (2003). Sci. Mar. (Barc.) 67(2): 241-248. Prabhu MS (1956). Maturation of intra-ovarian eggs and spawning periodicities in some fishes. Indian J. Fish. 2: 59-90. Qasim SZ (1973). An appraisal of the studies on maturation and spawning in marine teleosts from the Indian waters. Indian J. Fish. 20(1): 166-181. Smith MM, McKay RJ (1986). Haemulidae. In: MM Smith and PC Heemstra (eds) Smith’s sea fishes. p. 564-571. Springer-Verlag, Berlin.