- Email: [email protected]
Artificial reproduction of two different spawn-forms of the chub
Vol. 10, No. 1
67
SHORT COMMUNICATION
Articial reproduction of two different spawn-forms of the chub Sawomir Krejszeff1, Katarzyna Targoska, Daniel arski, Dariusz Kucharczyk Department of Lake and River Fisheries, University of Warmia and Mazury in Olsztyn, Poland
Received: 26 June 2009 ; accepted: 4 January 2010
SUMMARY The aim of this study was to compare, under controlled conditions, reproduction results of cultured and wild stock of the chub. Wild sh spawned only once a season whereas the cultured stock spawned at least two times. In the multiple-spawn stock, fewer sh spawned and the weight of produced oocytes was reduced compared to the single-spawn stock. Larvae obtained from the multi-spawn forms were smaller than those of the single-spawn stock. The occurrence of one species with two forms of spawning performance in the same area makes it difcult to develop an efcient method for controlling the reproduction. Reproductive Biology 2010 10 1: 67-74. Key words: articial spawning; ovulation; Leuciscus cephalus; cultured stock; wild population
1 Corresponding author: Department of Lake and River Fisheries, University of Warmia and Mazury in Olsztyn, ul. Oczapowskiego 5, 10-719 Olsztyn, Poland; e-mail: [email protected]
Copyright © 2010 by the Society for Biology of Reproduction
68
Articial reproduction of the chub
INTRODUCTION Chub Leuciscus cephalus (L.) has recently become an important cultured species in Polish aquaculture primarily due to the increased interest from recreational fisheries. Data concerning reproductive biology, hatchery techniques and methods of articial spawning of wild cyprinids including those of the chub are very limited [4, 7]. Development of controlled reproduction of wild cyprinids is an integral component of ongoing conservation efforts [16]. The articial spawning of the chub requires the application of spawning agents. Among a few tested spawning agents such as carp pituitary extract (CPH), human chorionic gonadotropin (hCG) and Ovopel (GnRHa-containing pellets combined with dopamine inhibitor), the latter was the most effective. The tactics of chub reproduction are still not clear. Chub spawners do not spawn spontaneously in captivity [6], the breeders are very sensitive to being caught and stress of handling. During our eight-year experience with controlled reproduction of wild L. cephalus in captivity, all sh spawned only once per season. In 2008, we observed that one stock of chubs spawned more than once during the spawning season. Some data [5] show that different spawning forms of this species were recognized in the area of their distribution: single-batch spawners (one spawning per season) or multiple spawners (2-3 spawnings during two-three months). The aim of this study was to compare, under controlled conditions, the results of reproduction of two different spawning forms of the chub.
MATERIAL AND METHODS Chub broodstock originated from two locations: cultured stock (F2 generation from the Warta River) from Knieja Fish Farm (southern Poland) and wild population from the Warta and Odra Rivers (western Poland). During the entire time of the experiment, the cultured stock was kept in earthen ponds under ambient conditions. The wild stock was collected in October 2007 and kept in a similar pond under the same conditions until spring 2008. Spawner size (250- 400 g) was similar in both stocks. Before spawning (May
Krejszeff et al
69
2008), all sh were transported to the hatchery (16°C; 14L:10D) and placed separately according to sex and stock in 1000 dm3 tanks. Aeration, water temperature (±0.1ºC) and daylight were controlled in each tank [14]. After ve days of acclimation, the temperature was raised to 18°C. All breeders were weighed and marked with oy-tags. Before hormonal stimulation, oocyte maturity was determined according to a four-degree scale: stage 1 – germinal vesicle in central position, stage 2 – early migration of germinal vesicle (less than half of radius), stage 3 – late migration of germinal vesicle (more than half of radius), stage 4 – periphery germinal vesicle or germinal vesicle breakdown (GVBD). Oocytes (~50 from each female) were collected with a catheter and placed in Serra’s solution. After the exposure to Serra solution (5 min), the position of the nucleus was determined and oocytes were photographed. Before manipulations, the sh were anaesthetized in a 2-phenoxyethanol solution (0.05%). The rst experiment was performed on wild (n=39) and cultured (n=40) females. The treated sh received a single injection of GnRHa-containing pellet (Ovopel; 1 pellet/kg). One Ovopel pellet (~25 mg) contains a mammalian GnRH analogue (D-Ala6, Pro9Net-mGnRH, 18-20 Pg) and dopamine antagonist, metoclopramide (8-10 mg). The control sh (n=10 females) were injected with saline (0.9% NaCl). In the second experiment, females previously stimulated by Ovopel were randomly divided into two groups: Ovopel-treated (1 pellet/kg; n=18 and n=22 for wild and cultured stock, respectively) or hCG-treated (500 IU/kg; n=18 and n=17 for wild and cultured stock, respectively). hCG was not used in the rst experiment due to its ineffectiveness usually observed in single-spawn cyprinids. However, hCG was found to be an effective spawning agent in cyprinids that are multiple spawners such as rudd Scardinius erythrophthalmus (L.), goldsh Carassius auratus (L.) and common tench Tinca tinca (L.) [10, 12, Targoska – unpublished]. Therefore, the application of hCG in the second experiment allowed us to support a thesis of a multi-spawn performance of the chub. The control females (n=10) were injected with saline (0.9% NaCl). Injections were applied intraperitoneally under the ventral n. Hormonal preparations were homogenized (Ovopel) or dissolved (hCG) in a sterile 0.9% NaCl. After the injection, the water temperature was raised from 18ºC to 19.5°C and was
70
Articial reproduction of the chub
kept constant during spawning. Before the rst and second reproductions, the sh were kept at 16°C. The between-spawning interval lasted 20 days and ended with the above-described thermal stimulation. Gametes were stripped manually. Semen was collected into syringes and kept at 4ºC. Eggs were collected into plastic containers by gently pressing the abdomen. The ovulation rate was recorded as well as female weight before ovulation and weight of obtained eggs. Pseudogonadosomatic index (PGSI) was calculated according to the formula: ([weight of eggs]×100%) / female weight. A small portion of eggs (approximately 100) was mixed with 0.05 cm3 of pooled milt, and gametes were activated by water addition. The diameter of oocytes was measured in each female. Egg incubation (each group from each population was incubated separately) was conducted in triplicates in a closed recirculation system. Eggs were incubated (19ºC) in Petri dishes placed in 1 dm3 glass aquaria which, in turn, were placed in a 50 dm3 water bath with continuous water ow (7 dm3/h). Each small aquarium had its overow secured with a mesh (size 200 μm) which prevented the escape of freshly hatched larvae. Larvae were measured after hatching and when over 50% of them started exogenous feeding. Oocytes and larvae were photographed with Leica MZ 12.5 microscope (Germany). All measurements (±0.01 mm) were done with ProgRes® Capture Pro 2.5 (Jenoptik, Germany) software. Data were expressed as means±SD. Statistical differences between the groups were determined using t-test at a signicance level of p<0.05.
RESULTS AND DISCUSSION Signicant progress in the propagation of sh from the genus Leuciscus has been made recently [4, 6, 17]. However, a reliable protocol for articial reproduction is still needed. The recognition of the best time for applying hormonal induction in cyprinid articial spawning is very important. In most single-batch spawning species the best method is examining the oocyte maturity stage [6, 7, 9, 11, 13, 17]. Oocytes of sh with more than one ovulation during spawning e.g. common tench, differ in size and maturity stage [12]. In such a case, the exact time for hormonal stimulation should be
Krejszeff et al
71
established experimentally. In the present study, the cultured stock oocytes were heterogeneous with regards to maturity stage and size (diameter), whereas the wild fish oocytes were homogenous (stage 2-3) and large. Oocyte diameter in the wild stock of the chub was 1.11±0.1 mm, whereas in the cultured multi-spawn form three oocyte sizes were distinguished: large (1.08±0.11 mm), medium (0.61±0.09 mm) and small (0.25±0.06). The average ratio for large, medium and small eggs was 38:27:35, respectively. All small and medium oocytes were in stage 1, whereas large oocytes had germinal vesicle in all four stages. The ovulation rate in Ovopel-treated wild stock (tab. 1) was similar to the previously reported [6]. The percentage of ovulation in the multiplespawn form was twofold lower than that of the single-batch form. Ovulation Table 1. Selected reproductive parameters (mean±SD) in the single-batch spawn and multiple-spawn chub Parameters
Single-batch spawn form (wild stock) Ovopel: rst spawning Ovulation rate (%) 36 PGSI (%) 12.8±2.3a Total length of larvae after 6.7±0.2a hatching (mm) Total length of larvae at the 8.0±0.2a beginning of exogenous feeding (mm) hCG: second spawning Ovulation rate (%) 0 PGSI (%) Ovopel: second spawning Ovulation rate (%) 0 PGSI (%)
Multi-spawn form (cultured stock)
-
Pseudogonadosomic index (PGSI): ([weight of eggs]×100%)/female weight Different superscripts within a row mean signicant (p<0.05) differences
20 4.1±1.5b 6.2±0.2b 7.7±0.3b
18 2.2±0.2 9 3.2 ± 0.2
72
Articial reproduction of the chub
was not demonstrated in the control groups. Despite sh being kept under favorable environmental conditions, no progress was observed in oocyte maturation expressed as germinal vesicle migration. This conrms the necessity of hormonal induction of ovulation in the chub in captivity. The same phenomenon was described in the single-batch spawn form of chub females stimulated with hCG [6] as well as in other cyprinids [7, 9, 11, 13, 17]. hCG is generally used for multiple-spawned marine sh species, e.g. snapper Pagrus auratus (L.) [2], mulloway Argyrosomus hololepidotus (Lacepède, 1801) [3] and sand whiting Sillago ciliata Cuvier (1829) [1]. In cyprinids, hCG alone is usually ineffective [9] with the exception of a few species [10, 12]. The inuence of hCG on the oocyte maturation is manifested by moving the nucleus towards the cell perimeter. However, hCG did not affect the sh strongly enough to start spawning. A similar phenomenon was observed in bream females [11]. The effectiveness of hCG was proven in cyprinids with portional ovulation: i.e. tench, rudd [10, 12] or Eurasian perch Perca uviatilis L. [8]. The females spawned during the second experiment were also found to spawn during the rst one. PGSI was higher in the singlespawn form (wild) than in the multiple-spawn form (cultured). The examined stocks did not differ in embryo survival to the eyed-egg stage. Larvae obtained from both stocks were different in size during hatching and at the start of exogenous feeding. Similar results were described for Eurasian perch originated from different stocks [15] and common carp reproduced during different periods of a season [13]. The size variation of sh larvae during hatching may be affected by stock origin or time of spawning. Larvae obtained from the single-spawn form (wild) were longer and more homogenous during hatching and at the start of the exogenous feeding than those from the multiple-spawn form (cultured). The differences in larvae size was noted in the common carp spawned within- and out-of season [13]. The cultured forms of chub collected from the southern Poland are multi-spawners. The main restrictions for controlling reproduction of the chub in captivity are difculties with hormonal stimulation as well as low numbers of ovulated females and obtained eggs. In future research, more spawning agents with wider dose range should be tested. Moreover, other hatchery techniques should be developed. The occurrence of one species
Krejszeff et al
73
with two forms of spawning performance in the same area makes difcult to develop an efcient method for the control of reproduction.
REFERENCES 1. Battaglene SC 1996 Hormone-induced ovulation of sand whiting (Sillago ciliata). Asian Fisheries Science 9 169-176. 2. Battaglene SC, Talbot RB 1992 Induced spawning and larval rearing of snapper, Pagrus auratus (Pisces, Sparidae), from Australian waters. New Zealand Journal of Marine and Freshwater Research 26 179-183. 3. Battaglene SC, Talbot RB 1994 Hormone induction and larval rearing of mulloway, Argyrosomus hololepidotus (Pisces, Sciaenidae). Aquaculture 126 73-81. 4. Cejko BI, Kowalski RK, Kucharczyk D, Targoska K, Krejszeff S, arski D, Glogowski J 2010 Inuence of the length of time after hormonal stimulation on selected parameters of milt of ide Leuciscus idus L. Aquaculture Research (in press). doi: 10.1111/j.13652109.2009.02357.x 5 .Fredrich F, Ohmann B, Curio B, Kirschbaum F 2003 Spawning migrations of the chub in the River Spree, Germany. Journal of Fish Biology 63 710-723. 6. Krejszeff S, Kucharczyk D, Kupren K, Targoska K, Mamcarz A, Kujawa R, Kaczkowski Z, Ratajski S 2008 Reproduction of chub, Leuciscus cephalus L., under controlled conditions. Aquaculture Research 39 907-912. 7. Krejszeff S, Targoska K, arski D, Kucharczyk D 2009 Domestication affects spawning of the ide (Leuciscus idus) – preliminary study. Aquaculture 295 145-147. 8. Kucharczyk D, Kujawa R, Mamcarz A, Skrzypczak A, Wyszomirska E 1996 Induced spawning in perch, Perca uviatilis L. using carp pituitary extract and HCG. Aquaculture Research 27 847-852. 9. Kucharczyk D, Kujawa R, Mamcarz A, Wyszomirska E 1997 Articial spawning in bream (Abramis brama L.). Polish Archives of Hydrobiology 44 201-205. 10. Kucharczyk D, Kujawa R, Mamcarz A, Wyszomirska E 1997 Induced spawning in rudd (Scardinius erythrophthalmus L.). Polish Archives of Hydrobiology 44 207-211. 11. Kucharczyk D, Kujawa R, Mamcarz A, Targoska-Dietrich K, Wyszomirska E, Glogowski J, Babiak I, Szabó T 2005 Induced spawning in bream (Abramis brama L.) using GnRH-containing pellets. Czech Journal of Animal Science 50 89-95. 12. Kucharczyk D, Kujawa R, Mamcarz A, Targoska K, Krejszeff S, Wyszomirska E 2007 Articial spawning of common tench (Tinca tinca L.) collected from wild populations. Polish Journal of Natural Sciences 22 37-45. 13. Kucharczyk D, Targoska K, Hliwa P, Gomuka P, Kwiatkowski M, Krejszeff S, Perkowski J 2008 Reproductive parameters of common carp (Cyprinus carpio L.) spawners during natural season and out-of-season spawning. Reproductive Biology 8 285-289. 14. Kujawa R, Kucharczyk D, Mamcarz A 1999 A model system for keeping spawners of wild and domestic sh before articial spawning. Aquacultural Engineering 20 85-89.
74
Articial reproduction of the chub
15. Mandiki SNM, Blanchard G, Mélard C, Koskela J, Kucharczyk D, Fontaine P, Kestemont P 2004 Effects of geographic origin on growth and food intake in Eurasian perch Perca uviatilis juveniles under intensive culture conditions. Aquaculture 229 117-128. 16. Wildt DE, Seal US, Rall WF 1993 Genetic resource banks and reproductive technology for wildlife. Genetic Conservation of Salmonid Fishes, pp 159-174. Eds Cloud JG, Thorgaard GH, Genetic Conservation of Salmonid Fishes, Plenum Press, New York. 17. arski D, Kucharczyk D, Targoska K, Jamróz M, Krejszeff S, Mamcarz A 2009 Application of Ovopel and Ovaprim and their combinations in controlled reproduction of two reophilic cyprinid sh species. Polish Journal of Natural Sciences 24 235-244.
67
SHORT COMMUNICATION
Articial reproduction of two different spawn-forms of the chub Sawomir Krejszeff1, Katarzyna Targoska, Daniel arski, Dariusz Kucharczyk Department of Lake and River Fisheries, University of Warmia and Mazury in Olsztyn, Poland
Received: 26 June 2009 ; accepted: 4 January 2010
SUMMARY The aim of this study was to compare, under controlled conditions, reproduction results of cultured and wild stock of the chub. Wild sh spawned only once a season whereas the cultured stock spawned at least two times. In the multiple-spawn stock, fewer sh spawned and the weight of produced oocytes was reduced compared to the single-spawn stock. Larvae obtained from the multi-spawn forms were smaller than those of the single-spawn stock. The occurrence of one species with two forms of spawning performance in the same area makes it difcult to develop an efcient method for controlling the reproduction. Reproductive Biology 2010 10 1: 67-74. Key words: articial spawning; ovulation; Leuciscus cephalus; cultured stock; wild population
1 Corresponding author: Department of Lake and River Fisheries, University of Warmia and Mazury in Olsztyn, ul. Oczapowskiego 5, 10-719 Olsztyn, Poland; e-mail: [email protected]
Copyright © 2010 by the Society for Biology of Reproduction
68
Articial reproduction of the chub
INTRODUCTION Chub Leuciscus cephalus (L.) has recently become an important cultured species in Polish aquaculture primarily due to the increased interest from recreational fisheries. Data concerning reproductive biology, hatchery techniques and methods of articial spawning of wild cyprinids including those of the chub are very limited [4, 7]. Development of controlled reproduction of wild cyprinids is an integral component of ongoing conservation efforts [16]. The articial spawning of the chub requires the application of spawning agents. Among a few tested spawning agents such as carp pituitary extract (CPH), human chorionic gonadotropin (hCG) and Ovopel (GnRHa-containing pellets combined with dopamine inhibitor), the latter was the most effective. The tactics of chub reproduction are still not clear. Chub spawners do not spawn spontaneously in captivity [6], the breeders are very sensitive to being caught and stress of handling. During our eight-year experience with controlled reproduction of wild L. cephalus in captivity, all sh spawned only once per season. In 2008, we observed that one stock of chubs spawned more than once during the spawning season. Some data [5] show that different spawning forms of this species were recognized in the area of their distribution: single-batch spawners (one spawning per season) or multiple spawners (2-3 spawnings during two-three months). The aim of this study was to compare, under controlled conditions, the results of reproduction of two different spawning forms of the chub.
MATERIAL AND METHODS Chub broodstock originated from two locations: cultured stock (F2 generation from the Warta River) from Knieja Fish Farm (southern Poland) and wild population from the Warta and Odra Rivers (western Poland). During the entire time of the experiment, the cultured stock was kept in earthen ponds under ambient conditions. The wild stock was collected in October 2007 and kept in a similar pond under the same conditions until spring 2008. Spawner size (250- 400 g) was similar in both stocks. Before spawning (May
Krejszeff et al
69
2008), all sh were transported to the hatchery (16°C; 14L:10D) and placed separately according to sex and stock in 1000 dm3 tanks. Aeration, water temperature (±0.1ºC) and daylight were controlled in each tank [14]. After ve days of acclimation, the temperature was raised to 18°C. All breeders were weighed and marked with oy-tags. Before hormonal stimulation, oocyte maturity was determined according to a four-degree scale: stage 1 – germinal vesicle in central position, stage 2 – early migration of germinal vesicle (less than half of radius), stage 3 – late migration of germinal vesicle (more than half of radius), stage 4 – periphery germinal vesicle or germinal vesicle breakdown (GVBD). Oocytes (~50 from each female) were collected with a catheter and placed in Serra’s solution. After the exposure to Serra solution (5 min), the position of the nucleus was determined and oocytes were photographed. Before manipulations, the sh were anaesthetized in a 2-phenoxyethanol solution (0.05%). The rst experiment was performed on wild (n=39) and cultured (n=40) females. The treated sh received a single injection of GnRHa-containing pellet (Ovopel; 1 pellet/kg). One Ovopel pellet (~25 mg) contains a mammalian GnRH analogue (D-Ala6, Pro9Net-mGnRH, 18-20 Pg) and dopamine antagonist, metoclopramide (8-10 mg). The control sh (n=10 females) were injected with saline (0.9% NaCl). In the second experiment, females previously stimulated by Ovopel were randomly divided into two groups: Ovopel-treated (1 pellet/kg; n=18 and n=22 for wild and cultured stock, respectively) or hCG-treated (500 IU/kg; n=18 and n=17 for wild and cultured stock, respectively). hCG was not used in the rst experiment due to its ineffectiveness usually observed in single-spawn cyprinids. However, hCG was found to be an effective spawning agent in cyprinids that are multiple spawners such as rudd Scardinius erythrophthalmus (L.), goldsh Carassius auratus (L.) and common tench Tinca tinca (L.) [10, 12, Targoska – unpublished]. Therefore, the application of hCG in the second experiment allowed us to support a thesis of a multi-spawn performance of the chub. The control females (n=10) were injected with saline (0.9% NaCl). Injections were applied intraperitoneally under the ventral n. Hormonal preparations were homogenized (Ovopel) or dissolved (hCG) in a sterile 0.9% NaCl. After the injection, the water temperature was raised from 18ºC to 19.5°C and was
70
Articial reproduction of the chub
kept constant during spawning. Before the rst and second reproductions, the sh were kept at 16°C. The between-spawning interval lasted 20 days and ended with the above-described thermal stimulation. Gametes were stripped manually. Semen was collected into syringes and kept at 4ºC. Eggs were collected into plastic containers by gently pressing the abdomen. The ovulation rate was recorded as well as female weight before ovulation and weight of obtained eggs. Pseudogonadosomatic index (PGSI) was calculated according to the formula: ([weight of eggs]×100%) / female weight. A small portion of eggs (approximately 100) was mixed with 0.05 cm3 of pooled milt, and gametes were activated by water addition. The diameter of oocytes was measured in each female. Egg incubation (each group from each population was incubated separately) was conducted in triplicates in a closed recirculation system. Eggs were incubated (19ºC) in Petri dishes placed in 1 dm3 glass aquaria which, in turn, were placed in a 50 dm3 water bath with continuous water ow (7 dm3/h). Each small aquarium had its overow secured with a mesh (size 200 μm) which prevented the escape of freshly hatched larvae. Larvae were measured after hatching and when over 50% of them started exogenous feeding. Oocytes and larvae were photographed with Leica MZ 12.5 microscope (Germany). All measurements (±0.01 mm) were done with ProgRes® Capture Pro 2.5 (Jenoptik, Germany) software. Data were expressed as means±SD. Statistical differences between the groups were determined using t-test at a signicance level of p<0.05.
RESULTS AND DISCUSSION Signicant progress in the propagation of sh from the genus Leuciscus has been made recently [4, 6, 17]. However, a reliable protocol for articial reproduction is still needed. The recognition of the best time for applying hormonal induction in cyprinid articial spawning is very important. In most single-batch spawning species the best method is examining the oocyte maturity stage [6, 7, 9, 11, 13, 17]. Oocytes of sh with more than one ovulation during spawning e.g. common tench, differ in size and maturity stage [12]. In such a case, the exact time for hormonal stimulation should be
Krejszeff et al
71
established experimentally. In the present study, the cultured stock oocytes were heterogeneous with regards to maturity stage and size (diameter), whereas the wild fish oocytes were homogenous (stage 2-3) and large. Oocyte diameter in the wild stock of the chub was 1.11±0.1 mm, whereas in the cultured multi-spawn form three oocyte sizes were distinguished: large (1.08±0.11 mm), medium (0.61±0.09 mm) and small (0.25±0.06). The average ratio for large, medium and small eggs was 38:27:35, respectively. All small and medium oocytes were in stage 1, whereas large oocytes had germinal vesicle in all four stages. The ovulation rate in Ovopel-treated wild stock (tab. 1) was similar to the previously reported [6]. The percentage of ovulation in the multiplespawn form was twofold lower than that of the single-batch form. Ovulation Table 1. Selected reproductive parameters (mean±SD) in the single-batch spawn and multiple-spawn chub Parameters
Single-batch spawn form (wild stock) Ovopel: rst spawning Ovulation rate (%) 36 PGSI (%) 12.8±2.3a Total length of larvae after 6.7±0.2a hatching (mm) Total length of larvae at the 8.0±0.2a beginning of exogenous feeding (mm) hCG: second spawning Ovulation rate (%) 0 PGSI (%) Ovopel: second spawning Ovulation rate (%) 0 PGSI (%)
Multi-spawn form (cultured stock)
-
Pseudogonadosomic index (PGSI): ([weight of eggs]×100%)/female weight Different superscripts within a row mean signicant (p<0.05) differences
20 4.1±1.5b 6.2±0.2b 7.7±0.3b
18 2.2±0.2 9 3.2 ± 0.2
72
Articial reproduction of the chub
was not demonstrated in the control groups. Despite sh being kept under favorable environmental conditions, no progress was observed in oocyte maturation expressed as germinal vesicle migration. This conrms the necessity of hormonal induction of ovulation in the chub in captivity. The same phenomenon was described in the single-batch spawn form of chub females stimulated with hCG [6] as well as in other cyprinids [7, 9, 11, 13, 17]. hCG is generally used for multiple-spawned marine sh species, e.g. snapper Pagrus auratus (L.) [2], mulloway Argyrosomus hololepidotus (Lacepède, 1801) [3] and sand whiting Sillago ciliata Cuvier (1829) [1]. In cyprinids, hCG alone is usually ineffective [9] with the exception of a few species [10, 12]. The inuence of hCG on the oocyte maturation is manifested by moving the nucleus towards the cell perimeter. However, hCG did not affect the sh strongly enough to start spawning. A similar phenomenon was observed in bream females [11]. The effectiveness of hCG was proven in cyprinids with portional ovulation: i.e. tench, rudd [10, 12] or Eurasian perch Perca uviatilis L. [8]. The females spawned during the second experiment were also found to spawn during the rst one. PGSI was higher in the singlespawn form (wild) than in the multiple-spawn form (cultured). The examined stocks did not differ in embryo survival to the eyed-egg stage. Larvae obtained from both stocks were different in size during hatching and at the start of exogenous feeding. Similar results were described for Eurasian perch originated from different stocks [15] and common carp reproduced during different periods of a season [13]. The size variation of sh larvae during hatching may be affected by stock origin or time of spawning. Larvae obtained from the single-spawn form (wild) were longer and more homogenous during hatching and at the start of the exogenous feeding than those from the multiple-spawn form (cultured). The differences in larvae size was noted in the common carp spawned within- and out-of season [13]. The cultured forms of chub collected from the southern Poland are multi-spawners. The main restrictions for controlling reproduction of the chub in captivity are difculties with hormonal stimulation as well as low numbers of ovulated females and obtained eggs. In future research, more spawning agents with wider dose range should be tested. Moreover, other hatchery techniques should be developed. The occurrence of one species
Krejszeff et al
73
with two forms of spawning performance in the same area makes difcult to develop an efcient method for the control of reproduction.
REFERENCES 1. Battaglene SC 1996 Hormone-induced ovulation of sand whiting (Sillago ciliata). Asian Fisheries Science 9 169-176. 2. Battaglene SC, Talbot RB 1992 Induced spawning and larval rearing of snapper, Pagrus auratus (Pisces, Sparidae), from Australian waters. New Zealand Journal of Marine and Freshwater Research 26 179-183. 3. Battaglene SC, Talbot RB 1994 Hormone induction and larval rearing of mulloway, Argyrosomus hololepidotus (Pisces, Sciaenidae). Aquaculture 126 73-81. 4. Cejko BI, Kowalski RK, Kucharczyk D, Targoska K, Krejszeff S, arski D, Glogowski J 2010 Inuence of the length of time after hormonal stimulation on selected parameters of milt of ide Leuciscus idus L. Aquaculture Research (in press). doi: 10.1111/j.13652109.2009.02357.x 5 .Fredrich F, Ohmann B, Curio B, Kirschbaum F 2003 Spawning migrations of the chub in the River Spree, Germany. Journal of Fish Biology 63 710-723. 6. Krejszeff S, Kucharczyk D, Kupren K, Targoska K, Mamcarz A, Kujawa R, Kaczkowski Z, Ratajski S 2008 Reproduction of chub, Leuciscus cephalus L., under controlled conditions. Aquaculture Research 39 907-912. 7. Krejszeff S, Targoska K, arski D, Kucharczyk D 2009 Domestication affects spawning of the ide (Leuciscus idus) – preliminary study. Aquaculture 295 145-147. 8. Kucharczyk D, Kujawa R, Mamcarz A, Skrzypczak A, Wyszomirska E 1996 Induced spawning in perch, Perca uviatilis L. using carp pituitary extract and HCG. Aquaculture Research 27 847-852. 9. Kucharczyk D, Kujawa R, Mamcarz A, Wyszomirska E 1997 Articial spawning in bream (Abramis brama L.). Polish Archives of Hydrobiology 44 201-205. 10. Kucharczyk D, Kujawa R, Mamcarz A, Wyszomirska E 1997 Induced spawning in rudd (Scardinius erythrophthalmus L.). Polish Archives of Hydrobiology 44 207-211. 11. Kucharczyk D, Kujawa R, Mamcarz A, Targoska-Dietrich K, Wyszomirska E, Glogowski J, Babiak I, Szabó T 2005 Induced spawning in bream (Abramis brama L.) using GnRH-containing pellets. Czech Journal of Animal Science 50 89-95. 12. Kucharczyk D, Kujawa R, Mamcarz A, Targoska K, Krejszeff S, Wyszomirska E 2007 Articial spawning of common tench (Tinca tinca L.) collected from wild populations. Polish Journal of Natural Sciences 22 37-45. 13. Kucharczyk D, Targoska K, Hliwa P, Gomuka P, Kwiatkowski M, Krejszeff S, Perkowski J 2008 Reproductive parameters of common carp (Cyprinus carpio L.) spawners during natural season and out-of-season spawning. Reproductive Biology 8 285-289. 14. Kujawa R, Kucharczyk D, Mamcarz A 1999 A model system for keeping spawners of wild and domestic sh before articial spawning. Aquacultural Engineering 20 85-89.
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Articial reproduction of the chub
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