Pakistan J. Zool., vol. 42(2), pp. 169-176, 2010. Reproductive Biology of Sailfin Molly, Poecilia latipinna (Lesueur, 1821) in Wadi Haneefah Stream, Riyadh, Saudi Arabia Ali S. Al-Akel*, Fahad Al-Misned, Hmoud F. Al-Kahem-Al-Balawi, Khalid A. Al-Ghanim, Zubair Ahmad and H. Annazri Zoology Department, Science college, King Saudi University, P. O. Box 2455, Riyadh, 11451, Kingdom of Saudi Arabia Abstract.- The reproductive biology of Poecilia latipinna inhabiting Wadi Haneefah stream, Riyadh, Saudi Arabia was studied. The fish (P. latipinna) were found reproductively active round the year. The highest reproductive activity occurred from February to May and August to November which defined two distinct annual periods of reproduction. There was a monthly variation in sex ratio. More females than males were registered during the whole period of study. Males mature at the total body length of 51 mm, while the female maturity was attained at 48 mm. Fifty percent male and female population achieved maturity at the length of 67 mm and 65 mm body length, respectively. The absolute fecundity of P. latipinna ranged from 35 to 161 eggs, the value of co-relation coefficient (r) indicates that the fish's fecundity has stronger relation with weight than with the length. Key words: Poecilia latipinna, reproductive biology, maturity, sex ratio, fecundity INTRODUCTION Reproduction is the process which occurs for the continuity of the gender. It differs according to fish type and environment; cold water fish reproduce once a year and have a short reproductive season, while warm water fish (tropical and subtropical) usually have a longer reproductive season which may extend from 7 to 9 months every year (Qasim, 1973). Reproduction of bony fish has attracted many researchers around the world (Ruzyeki, 1998; Pusey et al., 2001; Aday et al., 2002; Heibo and Vollestad, 2002; Machado et al., 2002; Privitera, 2002; Arlinghaus and Wolter, 2003; Orlando et al., 2007; Dominguez-Petit et al., 2008). Poecilia latipinna is an ornamental fish, originally occurring in North- Eastern area of USA and South America. It is widely distributed around the world and is a protein source (food) in some countries (Al-Ghanim, 2005) inspite of its small size. Besides that it serves as biological control for insects. P. latipinna was first record in Saudi Arabia in 1983 in Ank, the Eastern Sector (Ross, 1985), and * Corresponding author: zahmed@ksu.edu.sa or halkaham@ksu.edu.sa) 0030-9923/2010/0002-0169 $ 8.00/0 Copyright 2010 Zoological Society of Pakistan in Wadi Haneefah stream, Riyadh (central sector) by Siddiqui and Al-Harbi (1995). Many previous studies carried out on P. latipinna (an exotic species) in Wadi Haneefah stream have focused on its genetic nature and some biological aspects like feeding, age and growth besides the effects of salinity and temperature on behaviors of this species (Abrahams, 1988). The reproductive biology of this species, introduced in this environment, has not yet been studied. The present work aims at studing the reproduction of P. latipinna which includes sex ratio, monthly variations in gonado-somatic index , variations in the maturity stages and the relation between fecundity and total body weight and total length of the fish. MATERIALS AND METHODS Fish sampling and biological data: Monthly samples of P. latipinna were collected from Wadi Haneefah stream by cast net. A total of 360 specimens of P. latipnna were collected over a period of 15 months. Morphometric characteristics viz., wet weight and total length of each fish were recorded. All specimens were dissected, sexed and their gonads were removed and weighed to the nearest mg. Stage of maturity of each individual fish was determined and classified into following five 170 A.S. AL-AKEL ET AL. stages depending on its morphological conditions (Pusey et al., 2001). Stage I (Resting or Immature): Gonads look gray in color, small in size and stripe shape. Stage II (Early developing-stage): Ovary is pale or orange in color with few eggs. The testis extends inside a white casing. Stage III (Developing-stage): Ovary is orange in color with red spots; eggs are dark, can be seen by naked eyes and there were also droplets in the eggs. Testis is of white gray color. Stage IV (Late developing-stage): Ovary is of orange color and eggs are clearly visible. There are oily spots in a larger scale of the egg. Testes are of dark color between gray and white, no sperms are seen. Stage V (Gravid-stage): Color of ovaries tends to appear between yellow and orange and eggs are round and full of yolk, form small single drop. The testes are transparent and white; sperms are ejected by pressing the aperture genitals. Gonado-somatic index The monthly gonado-somatic index (GSI) was calculated from the following formula: These indices were expressed as the monthly averages and plotted against months. Sex ratio (SR) The sex ratio was calculated from the formula given below: Length at first maturation and 50% maturation The length of smallest matured fish is considered as length at first maturity. To estimate the size at 50% maturity (the size at which 50% fishes got matured) the fishes were grouped in 1mm group. The percentage of mature fishes were plotted against their corresponding lengths. The Lt 50, the length at which 50% fishes were mature, was then calculated as described by Caputo et al. (2003). Fecundity Fecundity was estimated by counting all the eggs found in the female ovary during the spawning season. Fish ovary was taken and put in small petri dish and the ova were separated from the ovarian tissue with the aid of dissecting needle, and all ripe ova were counted under the binocular microscope. Fish length and total weight were recorded separately for individual fish and plotted graphically against fecundity. The relationship between these variables and fecundity were estimated according to the following formula: F= aXb, Where F is fecundity, X is body weight in g or body length in mm, ‘a’ is intercept and ‘b’ is slope (Lagler, 1978). This equation became linear when transformed in logarithm as follows: Log F = log a + b log X. RESULTS Monthly variation in sexual maturity stages Data of monthly changes in the stages of sexual maturity is presented in Table I. It has been observed that part of P. latipinna population in Wadi Haneefah stream is reproductively active round the year. The highest reproductive activities seem to be occurring from February to May and August to November defining two distinct annual period of reproduction coinciding with the period of reduced water current and high availability of food (Lower water level and high planktonic population was reported by Al-Ghanim, 2005 in these months period). An irregular pattern of distribution of different maturity stages (I-V) was observed (Table I). Variations in gonado-somatic index (GSI) The monthly changes in GSI are presented in Figure 1. Male GSI remained lower as compared with females. GSI started to increase from February and attained the maximal value in May, decreased in June corresponding to their spawning season (Table I). The second spawning season was prolonged; it started from August till November with the peak value of gonado-somatic index in September. GONAD’S DEVELOPMENT AND FECUNDITY OF SAILFIN MOLLY 171 Table I.- Frequency of occurrence (percent) of different maturation stages for male and female of P.1latipinna in different months. 2 Months No. of fishes I 12 9 7 6 6 13 8 7 8 6 7 10 9 9 7 16.67 0.00 0.0 0.00 16.67 23.08 12.50 0.00 0.00 0.00 71.43 10.00 0.00 11.11 14.29 3 Feb 2003 Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan 2004 Feb Mar Apr Maturity stages in male II III IV 25.00 0.00 0.00 0.00 66.67 30.77 0.00 0.00 0.00 0.00 28.57 40.00 0.00 11.11 14.29 25.00 22.22 0.00 0.00 16.67 38.46 12.50 14.29 25.00 16.67 0.00 40.00 44.44 22.22 14.29 16.67 222.22 42.86 0.00 0.00 7.69 12.50 14.29 25.00 16.67 0.00 0.00 22.22 22.22 28.57 V No. of fishes I 16.67 55.56 57.14 100.00 0.00 0.00 62.50 71.43 50.00 66.67 0.00 10.00 33.33 33.33 28.57 10 13 15 16 16 9 14 15 14 16 15 13 14 13 15 20.00 0.00 33.33 0.00 62.50 33.33 7.14 0.00 0.00 6.25 40.00 61.54 0.00 0.00 20.00 Maturity stages in female II III IV 70.00 38.46 0.00 6.25 12.50 11.11 0.00 13.33 0.00 0.00 13.33 0.00 35.71 15.38 13.33 0.00 7.69 13.33 6.25 6.25 22.22 7.14 6.67 21.43 12.50 6.67 15.38 42.86 7.69 13.33 0.00 23.08 13.33 12.50 6.25 33.33 28.57 6.67 28.57 25.00 20.00 15.38 14.29 30.77 20.00 V 10.00 30.77 40.00 62.50 6.25 0.00 57.14 73.33 50.00 56.25 20.00 7.69 7.14 38.46 33.33 4 Sex ratio Data of monthly changes in the sex ratio are presented in Figure 2. Generally, the females were higher in numbers than males during the whole period of the study except in February and July. Length at first maturation and 50% maturation The total length of smallest specimens of P. latipinna netted from Wadi Haneefah Stream was 39 mm (male) and 45 mm (female). They achieved the first maturity at total length of 51 mm and 48 mm (male and female, respectively). It is registered that 50% of the fish matured at the length of 65 mm (male) and 67 mm (female). Both male and female fish at around 80 mm of body length showed 100% maturation in active reproductive periods (Fig. 3A and B). Fecundity The observed and calculated fecundity of P. latipinna, on the basis of length, ranged between 35 - 161 and 29.03 - 185.95 eggs respectively. The relative fecundity in relation to length ranged between 0.55 - 2.05 (egg/mm), whereas the range in relation to weight was 2.10 - 13.30 (eggs/g). Logarithmic relationship between the mean length and absolute or calculated fecundity is represented in Figure 4 A & B. The relationship obtained was as follows: Log F = - 3.112 + 2.721 Log L, whereas the correlation coefficient (R) is 0.67 which showed a significant relationship. Similarly, Figure 5 A and B shows the relationship between wet body weight of the fish and absolute fecundity as follows: Log F= 1.049 +1.11 Log W, with significant correlation coefficient (R = 0.85). The relationship between mean weight and calculated fecundity is as follows: Log F = 1.049 + 1.114 log W. This relationship is highly significant (correlation coefficient, R = 1.0). Regression analysis of total weight with absolute fecundity and relative fecundity of P. latipinna indicated that absolute fecundity has a good relation with total weight (r=0.64) and total length (r=0.56). DISCUSSION Limitations of breeding to a particular season was postulated for temperate zone fishes where the habitat is dominated by pronounced annual cycles of photoperiodicity, thermal variations and food availability (Bagenal and Erich,1978; Scott, 1979). Continuity of breeding seems well suited the tropical freshwater fishes where the stability of essential conditions tend to prevail for most of the year. A.S. AL-AKEL ET AL. 172 Spring (Male) Summer Fall (Female) Winter (Combined) Gonadosomatic index 30 25 20 15 10 5 0 0 Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Months 1 Fig. 1. Monthly changes in gonadosomatic indeces of males, females and combined sexes of P2 . Wadi Haneefah stream,Riyadh. 3 4 Spring Male 100 Summer Fall latipinna in Winter Female Sex ratio (%) 80 60 40 20 0 0 Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Months Fig. 2. Sex ratio in (percent) of P. latipinna in Wadi Haneefah stream, Riyadh. 5 6 7 GONAD’S DEVELOPMENT AND FECUNDITY OF SAILFIN MOLLY 173 8 100 2.50 (A) Lt50 =67mm 2.25 Log10 observed fecundity percent maturation 90 80 70 60 50 40 Log F = - 3.112 + 2.721 Log L , R = 0.67 (A) 2.00 1.75 1.50 1.25 1.6 30 45 50 55 60 65 70 75 80 85 90 95 100 1.7 1.8 1.9 2.0 2.1 2.0 2.1 Log10 mean length (mm) Total Length (mm) 2.50 100 (B) Lt50=69mm Log10 calculated fecundity 90 percent maturation 80 70 60 50 40 30 2.25 (B) 2.00 1.75 1.50 1.25 1.6 20 Log F = - 3.112 + 2.721 Log L , R =1.0 1.7 1.8 1.9 Log10 mean length (mm) 10 45 50 55 60 65 70 75 80 85 90 Total length (mm) Fig. 3. Relationship between total length and percentage of matured females (A) and males (B) of P. latipinna. Fish ovaries showed periodic seasonal changes in weight. In the present work, the monthly changes in gonado-somatic-index indicated two prolonged seasons; the first spawning season extended from February till May, the GSI started to increase from February, attained the maximal value in May and then decreased sharply in June. The second spawning season was longer; it started from July till November with a peak in September. This observation coincides well with stage V (mature fish) found from February to May and August to November, and corresponds to the period of reduced water level and high availability of food (Al-Kahem et al., 2007). Fig. 4. Logarithmic relationship between length and observed (A) and calculated fecundity (B) of P. latipinna in Wadi Haneefah stream, Riyadh. Welcomme (1979), Tomasson et al. (1984) and Townshend and Wooton (1984) have studied the spawning of P. latipinna and suggested that flooding, water current, elevated silting, lower visibility and availability of breeding ground as well as food may trigger or induce breeding in fishes. The reduced reproductive activities of Poecilia latipinna in June, July , December and January is probably related to above mentioned factors. A concentrated reproductive efforts in the months which witnesses minimum discharge is reported for subtropical stream dwelling fishes (Milton and Arthington, 1985) and this is acceptable in the sense that larvae produced at this time were less likely to experience high mortality than during elevated flow (Pusey et al., 2001). A.S. AL-AKEL ET AL. 174 Log10 observed fecundity 2.50 2.25 Log F = 1.049 + 1.114 Log L , R = 0.85 (A) 2.00 1.75 1.50 1.25 0.25 0.50 0.75 1.00 1.25 1.00 1.25 Log10 mean weight (gm) Log10 calculated fecundity 2.50 2.25 Log F = 1.049 + 1.114 Log L , R = 1.0 (B) 2.00 1.75 1.50 1.25 0.25 0.50 0.75 Log10 mean weight (gm) Fig. 5. Logarithmic relationship between weight and observed (A) and calculated fecundity (B) of P. latipinna in Wadi Haneefah stream, Riyadh. The sex ratio indicates the proportion of males with females in the population which is expected to be 1:1 in nature. This type of study indicates segregation or aggregation of sexes according to feeding, breeding and migratory behaviour. Previous studies indicate that the females dominate over males (Bhatt, 1972; Thompson and Munro, 1978; Ghorab et al., 1986; Zabala et al., 1997). Equal number of males and females were reported by Yabe (1954). Disparities in assumed sex ratio (1:1) were also reported by Marr (1948), Wade (1950) and Raju (1963). Domination of females over males in all the months except in the peak spawning period was reported by Hashim and Salamah (1985) and Coleman et al. (1996). Tamaru et al. (1996) have reported that male of Epinephelus microdon dominates (4:1) over female. In the present study females outnumber males in all the months of the year. The variations in the sex ratios depend mainly upon the size of the samples analyzed, spawning migration, exploitation, weather condition at the time of catch, gear used and sex reversal (Batts, 1972; Thomson and Munro, 1978; Hashim and Salamah, 1985; Ghorab et al., 1986). Majority of fishes are oviparous but few like sharks and guppies (live bearer) are ovo-viviparous. Parental care is apparent in ovo-viviparous fishes as they produce little number of eggs. On the other hand, oviparous fishes are more fecund (produce more eggs) probably because of the less survival chance due to environmental hazards. The detrimental effect of this low fecundity is probably mitigated by parental care behaviour which is a common feature of molly, P. latipinna (Moyle and Cech, 1982). This parental care behaviour and low fecundity was also reported in gobiis, Economidichthys pygmaeus and Crystallogobius linearis by Daoulas et al. (1993) and Caputo et al. (2003), respectively, and extend considerable support to present investigation. Hence, the energetic investment in reproduction tends to be higher, where the smaller fishes spend more energy on growth thus producing less and smaller eggs (Moyle and Cech, 1982; AlDhahi, 2000). Results of Ghorab et al. (1986) and Al-Dhahi (2000) indicate that the environmental conditions also affect the fecundity of fishes as E. chlorostigma have different fecundity in two different environments (Red Sea and Arabian Gulf). 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