(Cyprinidae), in Bibi-Sayyedan River, Tigris Basin
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NORTH-WESTERN JOURNAL OF ZOOLOGY 11 (1): 163-170 ©NwjZ, Oradea, Romania, 2015 Article No.: 141402 http://biozoojournals.ro/nwjz/index.html Reproductive biology and gonad histology of the Kura Barbel, Barbus lacerta (Cyprinidae), in Bibi-Sayyedan River, Tigris basin Hakimeh DOPEIKAR1, Yazdan KEIVANY1,* and Mohammad SHADKHAST2 1. Department of Natural Resources (Fisheries Division), Isfahan University of Technology, Isfahan 84156-83111, Iran. 2. Department of Basic Science, Faculty of Veterinary, Shahrekord University, Shahrekord, Iran. *Corresponding author, Y. Keivany, Phone: +98 (31) 3391-3572, Fax: +98 (31) 3391-2840, E-mail: [email protected] Received: 06. June 2014 / Accepted: 10. October 2014 / Available online: 17. January 2015 / Printed: June 2015 Abstract. Maturity age, spawning period, fecundity and gonad histology of the Kura Barbel in Bibi-Sayyedan River of Semirom (Tigris basin) were determined. A total of 445 specimens were captured by monthly collections from August 2010 to July 2011. Specimens were caught by electrofishing, seine net and cast net and transported to the laboratory on ice for further examination. The sex ratio was determined as 1.8M:1F, a ratio significantly different from the expected ratio. Males and females become sexually mature in their first year. Gonadosomatic Index (GSI) value was the highest in April for both sexes. Mean ± SE of absolute fecundity was 8249 ± 997 eggs and also, the relative fecundity was 140 egg/g body weight. Based on the results of GSI, egg diameter and histological studies, spawning period of this fish occur from late March to August with a peak in April. Key words: Cypriniformes, gonad development, egg diameter, gonadosomatic index, reproduction. Introduction cyte development (Selman & Wallace 1989). In the case of synchronic oogenesis, all the oocytes de- Kura Barbel (Blizem in Farsi) is a cyprinid fish velop at the same time, ovulation also being si- widely distributed in Iran and adjacent countries. multaneous. The group synchronous ovary con- This species is found in Tigris (Karun and Kark- sists of at least two populations of the oocytes at heh river basins), Caspian Sea and Urmia basins in different developmental stages; teleosts with this Iran (Abdoli 2000, Keivany et al. 2015, Coad 2014), type of ovary generally spawn once a year and however, the reproductive biology of this species have a relatively short breeding season. In the case is not well documented in Iran and other coun- of asynchronic ovulation, different development tries, partly because this fish is not of commercial stages of the oocyte maturation and ovulation in importance due to its slow growth rate and small groups may be found within the ovaries (Na- size. Nevertheless, it is used as an edible fish at a gahama 1983, Nejedli et al. 2004). local scale and hence, there is no information on The aim of this study is to investigate the re- its landings. productive biology and gonadal histology of B. Success of reproduction depends upon normal lacerta in Bibi-Sayyedan River of Semirom by vis- gonadal development stimulated by favorable en- ual observation and gonad histology. The results vironmental conditions. Photoperiod and tem- of this study could be used for management pur- perature are the most important factors for con- poses of this species. trolling the reproductive activities in most season- ally breeding teleosts (Lam 1983, Shankar et al. 2007) including cyprinids (Hontela & Stacey 1990). Materials and methods Reproductive development in fishes is well under- Bibi-Sayyedan River is located approximately 18 km stood by histological techniques which are the south of the town of Semirom. This river is flowing south- most reliable method to determine the reproduc- westward from the high central part of Zagros Mountain, tive state of fishes (West 1990). The ovarian histo- joining Marbor River and terminating in Khersan River a logical pattern of teleosts is described according to tributary of Karun River (Tigris basin). For this study, 445 the division of ovarian tissues into seven or eight specimens were captured by monthly collection from Au- (Crim & Glebe 1990) or five (Brown-Peterson et al. gust 2010 to July 2011 at 31° 11' 0.8" N, 51° 26' 59" E. Specimens were caught by electrofishing, seine net and 2011) stages of maturity based upon the presence cast net, anesthetized and transported to the laboratory of dominant gametogenic cell types. on ice and subjected to dissection and biometric meas- The ovaries of the fishes have been classified urements (length to the nearest 0.1 cm, and weight to the into three types according to the pattern of the oo- nearest 0.01 g). For each specimen, 10-15 scales were re- 164 H. Dopeikar et al. moved from above the lateral line below the anterior ex- Assessment of the main spawning period of B. tent of the dorsal fin on the left side of the fish, washed in lacerta in Bibi-Sayyedan River was based on the water and dried between two slides for microscopic stud- GSI (Fig. 1), analysis of seasonal development in ies (Lagler, 1956). Scales, mounted dry between glass mean egg diameter (Fig. 2), and direct observation slides, were used for age estimation and were read by three people. Sex was determined by examination of the of the gonads. Significant differences were found gonads. The sex ratio deviation from 1:1 was tested statis- in the males and females GSI and egg diameter (p tically by chi-squared analysis (Sokal & Rohlf 1981). < 0.05) in different months. The highest GSI value The relative gonad weight or gonadosomatic index for both sexes occurred in April and then started (GSI) of females and males were calculated as the propor- to decrease. But only in females it increased tion of the weight of the gonad to the weight of eviscer- slightly in October again (Fig. 1). Thus, the repro- ated body in percent. Also, water temperature was meas- ductive period for this species in this particular ured to determine the relationship between temperature and gonad growth by a digital thermometer. The absolute environment is from March to August when GSI is fecundity was determined by the gravimetric method. considerably higher. Some unspent individuals While relative fecundity was determined as the propor- were observed among the population during this tion of absolute fecundity to the eviscerated body weight period. The mean ± SE of the absolute fecundity of (number of mature eggs per gram of the body weight). 23 females determined during the spawning pe- Egg diameter was measured with an ocular micrometer. riod was 8249 ± 997 egg and relative fecundity was The ovaries and testes were processed according to 140 egg/g body weight. The Mean egg diameter standard histological techniques (Humason 1979). All tis- sue blocks were sectioned at 5-6 μm and stained with he- was significantly different during the year (P< matoxylin and eosin. Histological slides were viewed un- 0.05). Obviously, the highest mean egg diameter der a light microscope. Maturity stages were determined (0.745 ± 0.058 mm) was observed in April and the following Brown-Peterson et al. (2011). lowest in September (0.336 ± 0.011 mm) (Fig. 2). After identifying the various stages of sexual matura- The highest egg diameter was observed in April tion, diameter of sex cells were measured during different (2.25 mm). growth phases under magnifications of ×100 by a mi- The lowest temperature was in March and crometer. Reproductive seasonality was determined by examination of the monthly changes in the gonadoso- then began to increase in April along with daytime matic index and the water temperature, recorded during and a sudden increase in river flooding (Fig. 3). the sampling (10.5 to 21.4 C°), in Bibi-Sayyedan River. A Therefore, based on macroscopic, microscopic and One-way ANOVA was used to analyze differences in environmental variations, the spawning period of means of GSI% and egg diameter of fish at 5% probability B. lacerta continued approximately from late level in SPSS 18 computer software. March to late August when water temperature was between 17.2 and 19.9°C. The gonad development stages of B. lacerta are Results described in five stages following Brown-Peterson The length and weight of females ranged from 6.4 et al. (2011) which has been accepted by many re- to 23.3 cm and 2.65 to 123.17 g and those of males searchers as the standard procedure (e.g. Tom- from 5.7 to 18.4 cm and 2.02 to 58.8 g, respectively. kiewicz et al. 2011, Grier 2012, Abaszadeh et al. In all specimens, they varied from 2.6-23.3 cm and 2013). 0.17-123.17 g. In general, females were larger than males. Monthly variations in the frequency, total Stage I (never spawned). Testes and ovaries were length (cm) and total weight (g) of all samples are very small and near the spinal column, often clear shown in Table 1. The specimens were composed and threadlike and transparent grayish in color, of 49.6% males, 32.1% females and 18.9% imma- blood vessels indistinct. Eggs were not visible to ture. The ratio of male to female was 1.8M:1F the naked eye and sex could not be distinguished which was significantly different from the ex- (Fig. 4A). The mean diameter of oocytes was 4.714 pected 1:1 ratio (χ2 = 16.866, p < 0.01). The oldest ± 0.521(SE) µm. In histological sections of ovaries, males and females were 4 and 7 years old, respec- only oogonia and primary growth (PG) oocytes tively. Although older fish may have been existed were present. No atresia. Ovarian walls were thin in the river, they were not caught because of net and there was little space between oocytes.