Effects of age and size on reproductive performance of captive Farfantepenaeus paulensis broodstock Farfantepenaeus paulensis 生殖群的年齡和大小對生殖情況的影響 Aquaculture 238 (2004) 173 – 182 Silvio Peixoto*, Ronaldo O. Cavalli, Wilson Wasielesky, Fernando D ’ Incao, Dariano Krummenauer, A ˆ ngela M. Milach REPORTER : SHIH YI – JIA

Introduction

蝦業介紹 : Penaeid shrimp Farfantepenaeus paulensis is a native species Penaeid shrimp Farfantepenaeus paulensis is a native species In the western Atlantic Ocean from Ilhe´us Brazil to Mar del Plata Argentina (D’Incao, 1991). In the western Atlantic Ocean from Ilhe´us Brazil to Mar del Plata Argentina (D’Incao, 1991). This species has been considered a suitable shrimp either for pond farming (Peixoto et al., 2003a) or for estuarine pen culture in southern Brazil (Wasielesky et al., 2000). This species has been considered a suitable shrimp either for pond farming (Peixoto et al., 2003a) or for estuarine pen culture in southern Brazil (Wasielesky et al., 2000). Ilhe´us

蝦業介紹 : Nauplii production of Farfantepenaeus paulensis originally relied on the use of wild breeders (Marchiori and Boff, 1983; Marchiori and Cavalli, 1993), Nauplii production of Farfantepenaeus paulensis originally relied on the use of wild breeders (Marchiori and Boff, 1983; Marchiori and Cavalli, 1993), Recent studies have focused on the management and reproduction of captive broodstock due to the unpredictability and high costs associated with the capture of the wild stocks (Cavalli et al., 1997; Peixoto et al., 2003b). Recent studies have focused on the management and reproduction of captive broodstock due to the unpredictability and high costs associated with the capture of the wild stocks (Cavalli et al., 1997; Peixoto et al., 2003b).

前人研究 : Several studies have been performed to close the life cycle and improve reproductive performance of different penaeid species in captivity (Ogle, 1992; Luis and Ponte, 1993; Makinouchi and Hirata, 1995; Ramos et al., 1995). Several studies have been performed to close the life cycle and improve reproductive performance of different penaeid species in captivity (Ogle, 1992; Luis and Ponte, 1993; Makinouchi and Hirata, 1995; Ramos et al., 1995). Nevertheless, it is difficult to separate whether reproductive performance is age- or size-dependent as shrimps of similar size may not be of the same age and vice versa (Dall et al., 1990; Bray and Lawrence, 1992). Nevertheless, it is difficult to separate whether reproductive performance is age- or size-dependent as shrimps of similar size may not be of the same age and vice versa (Dall et al., 1990; Bray and Lawrence, 1992).

前人研究 : The effect of age on reproductive performance has been assessed traditionally by either using know-age pond-reared broodstock (Primavera, 1978; Motoh, 1981; Makinouchi and Hirata, 1995;Ramos et al., 1995; Cavalli et al., 1997) or age estimations based on length– frequency analysis for wild-caught shrimps (Crocos and Coman, 1997; Cavalli et al., 1997; Peixoto et al., 2003b; Coman and Crocos, 2003). The effect of age on reproductive performance has been assessed traditionally by either using know-age pond-reared broodstock (Primavera, 1978; Motoh, 1981; Makinouchi and Hirata, 1995;Ramos et al., 1995; Cavalli et al., 1997) or age estimations based on length– frequency analysis for wild-caught shrimps (Crocos and Coman, 1997; Cavalli et al., 1997; Peixoto et al., 2003b; Coman and Crocos, 2003).

本次研究動機 : Few studies have simultaneously compared the influence of age and size on the maturation of penaeid females (Hoang et al.,2002) and males (Ceballos-Va´squez et al., 2003) from the same breeding population. Few studies have simultaneously compared the influence of age and size on the maturation of penaeid females (Hoang et al.,2002) and males (Ceballos-Va´squez et al., 2003) from the same breeding population.

本次研究目的 : To evaluate the influence of different ages (10 and 16 months old) and sizes on the reproduction of F. paulensis females and males reared under captive conditions. To evaluate the influence of different ages (10 and 16 months old) and sizes on the reproduction of F. paulensis females and males reared under captive conditions. This knowledge may provide a further basis for the selection of broodstock with improved reproductive performance. This knowledge may provide a further basis for the selection of broodstock with improved reproductive performance.

Material and methods

Experimental design: Reproductive performance was assessed in two trials at the Reproductive performance was assessed in two trials at the Ages of 10 and 16 months. Ages of 10 and 16 months. Two size classes were established for males and females based on the frequency distribution for body weight and carapace length. Two size classes were established for males and females based on the frequency distribution for body weight and carapace length.

Rearing of broodstock: Postlarvae (PL) were produced from wild broodstock captured offshore in southern Brazil at depths of 35–40 m. Postlarvae (PL) were produced from wild broodstock captured offshore in southern Brazil at depths of 35–40 m.

箱網養殖場 飼養一個月 移至箱網養殖場 飼養五個月後 生殖場 smalllarge 同年級群 無節幼體 孵卵場 L10 L16 S10S16

10-month 16-month Large small 100ml 卵粒採集及記數 :

Male quality and spawning performance: Females with mature ovaries (stage III) were sourced out daily at 1800 h, according to the criteria proposed by (Peixoto et al. (2003c) Females with mature ovaries (stage III) were sourced out daily at 1800 h, according to the criteria proposed by (Peixoto et al. (2003c) The number of eggs was estimated from three 100-ml replicate samples of the spawning tank water, collected after homogenization. The number of eggs was estimated from three 100-ml replicate samples of the spawning tank water, collected after homogenization.

Male quality and spawning performance: Hatching rates and metamorphosis to the first protozoa stage (PZI) were obtained by placing random samples of, respectively, 100 eggs and 100 nauplii in three 1-l beakers with gentle aeration and controlled water temperature. Hatching rates and metamorphosis to the first protozoa stage (PZI) were obtained by placing random samples of, respectively, 100 eggs and 100 nauplii in three 1-l beakers with gentle aeration and controlled water temperature.

Male quality and spawning performance: 產卵率推估 : 產卵率推估 : Between eyestalk ablation and first spawn, spawning rate (number of spawns/female stocked). Between eyestalk ablation and first spawn, spawning rate (number of spawns/female stocked). 產卵間隔日推估 : 產卵間隔日推估 : spawning interval (for successive spawns), spawning interval (for successive spawns), 卵數估計 : 卵數估計 : number of eggs per spawning number of eggs per spawning 每隻產卵的卵數 每隻產卵的卵數 number of eggs per female number of eggs per female (total egg production/female stocked). (total egg production/female stocked). 雌性產卵的平均卵數 雌性產卵的平均卵數 產卵率推估 : 產卵率推估 : Between eyestalk ablation and first spawn, spawning rate (number of spawns/female stocked). Between eyestalk ablation and first spawn, spawning rate (number of spawns/female stocked). 產卵間隔日推估 : 產卵間隔日推估 : spawning interval (for successive spawns), spawning interval (for successive spawns), 卵數估計 : 卵數估計 : number of eggs per spawning number of eggs per spawning 每隻產卵的卵數 每隻產卵的卵數 number of eggs per female number of eggs per female (total egg production/female stocked). (total egg production/female stocked). 雌性產卵的平均卵數 雌性產卵的平均卵數

Male quality and spawning performance: Males had their spermatophores extruded by gently pressing around the coxae of the fifth pair of pereopods (Petersen et al., 1996). Males had their spermatophores extruded by gently pressing around the coxae of the fifth pair of pereopods (Petersen et al., 1996).

Ovarian histology: Histological analysis of mature ovaries was performed by selecting ready-to- spawn females 2 weeks after eyestalk ablation. Histological analysis of mature ovaries was performed by selecting ready-to- spawn females 2 weeks after eyestalk ablation. Gonadosomatic index (GSI) = Gonadosomatic index (GSI) = 性腺重 / 體重 性腺重 / 體重

Statistical analysis: Based on the size and age of females and males, four treatments were established: Based on the size and age of females and males, four treatments were established: S10 (small class, 10 months old) S10 (small class, 10 months old) L10 (large class, 10 months old) L10 (large class, 10 months old) S16 (small class, 16 months old) S16 (small class, 16 months old) L16 (large class, 16 months old). L16 (large class, 16 months old).

Statistical analysis: Oneway ANOVA Oneway ANOVA Tukey posthoc comparison test Tukey posthoc comparison test

Results Results

噬酸性卵細胞 前期卵細胞 噬鹼性卵細胞

Discussion

Previous studies have reported that larger males of Penaeus monodon (Pratoomchat et al., 1993) produced significantly heavier spermatophores and larger numbers of sperm cells per spermatophore) Previous studies have reported that larger males of Penaeus monodon (Pratoomchat et al., 1993) produced significantly heavier spermatophores and larger numbers of sperm cells per spermatophore) Similarly, the spermatophore weight and sperm count per spermatophore were positively correlated to body weight for Litopenaeus vannamei (Ceballos-Va´squez et al., 2003). Similarly, the spermatophore weight and sperm count per spermatophore were positively correlated to body weight for Litopenaeus vannamei (Ceballos-Va´squez et al., 2003).

Showed that spermatophore weight increased significantly with the size of Pleoticus muelleri but sperm count remained unchanged. Dı´az et al. (2001) Showed that spermatophore weight increased significantly with the size of Pleoticus muelleri but sperm count remained unchanged. Dı´az et al. (2001) In accordance, the present results for F. paulensis indicate that significant differences in spermatophore weight were probably related to male size, especially among the S10, L10 and S16 groups but these differences do not necessarily imply differences in sperm count. In accordance, the present results for F. paulensis indicate that significant differences in spermatophore weight were probably related to male size, especially among the S10, L10 and S16 groups but these differences do not necessarily imply differences in sperm count.

Sexual maturity of wild and captive F. paulensis males is known to occur at an early stage (6 months old) of their life. Sexual maturity of wild and captive F. paulensis males is known to occur at an early stage (6 months old) of their life. It is unlikely that the lack of fertile spawns for S10 females could be attributed to a lack of sperm as spermatophores were observed in the thelycum after molting and the sperm count was similar to the older and larger males (except the L16 group).

Sexual maturity and breeding of pond- reared females varies among species (Bray and Lawrence, 1992), with the youngest reported spawning event of a captive penaeid at 5 months old (Primavera, 1978). Hoang et al. (2002) Sexual maturity and breeding of pond- reared females varies among species (Bray and Lawrence, 1992), with the youngest reported spawning event of a captive penaeid at 5 months old (Primavera, 1978). Hoang et al. (2002) Overall performance of captive Fenneropenaeus merguiensis increased from 7 to 10 months old and declined at Overall performance of captive Fenneropenaeus merguiensis increased from 7 to 10 months old and declined at 13 months old. 13 months old.

Performance of wild Penaeus semisulcatus broodstock was reported to increase from the time of first maturity until 12 months old but declined afterwards (Crocos and Coman, 1997; Coman and Crocos, 2003). Performance of wild Penaeus semisulcatus broodstock was reported to increase from the time of first maturity until 12 months old but declined afterwards (Crocos and Coman, 1997; Coman and Crocos, 2003). Accordingly, Cavalli et al. (1997) argued that senescence was probably the reason for the inferior spawning performance of wild F. paulensis with estimated age of 16.5 months old. Accordingly, Cavalli et al. (1997) argued that senescence was probably the reason for the inferior spawning performance of wild F. paulensis with estimated age of 16.5 months old.

Histological analysis confirmed that maturation (stage III) was attained by L10 females, the presence of yolky oocytes (stage II), lower frequency of cortical oocytes (CO), smaller diameter of CO and lower GSI value may indicate a reduced vitellogenic activity compared to 16- month-old females. Histological analysis confirmed that maturation (stage III) was attained by L10 females, the presence of yolky oocytes (stage II), lower frequency of cortical oocytes (CO), smaller diameter of CO and lower GSI value may indicate a reduced vitellogenic activity compared to 16- month-old females.

summary

雄性精囊重會隨年齡及體型改變而改變, 但精 蟲數最多時出現在 L16 時 雄性精囊重會隨年齡及體型改變而改變, 但精 蟲數最多時出現在 L16 時 在同齡雌蝦中, 體型越大者 其生殖情形越好 在同齡雌蝦中, 體型越大者 其生殖情形越好 在生殖雌蝦中, 蝦齡越大者, 其生殖情形越好 在生殖雌蝦中, 蝦齡越大者, 其生殖情形越好 養殖的雌蝦生殖群, 卵巢退化發生較晚, 原因 可能因為有剪除單眼眼柄, 使其卵巢持續發育 時間較長 養殖的雌蝦生殖群, 卵巢退化發生較晚, 原因 可能因為有剪除單眼眼柄, 使其卵巢持續發育 時間較長

本實驗推測 雌蝦齡及蝦體大小皆可以影響 其生殖情形 而蝦體大小影響生殖情形較蝦齡的影響來 的大 而蝦體大小影響生殖情形較蝦齡的影響來 的大

Thank you for your attention

噬酸性卵細胞 前期卵細胞 噬鹼性卵細胞