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Hatch Rate (hatch + rate)
Selected AbstractsInbreeding Effects on Hatchery and Growout Performance of Pacific White Shrimp, Penaeus (Litopenaeus) vannameiJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2008Dustin R Moss In animal breeding programs, selection coupled with a narrow genetic base can cause high levels of inbreeding to occur rapidly (in one or two generations). Although the effects of inbreeding have been studied extensively in terrestrial animals and to a lesser extent in aquaculture species, little is known about the effects of inbreeding on penaeid shrimp. The objective of this study was to investigate the effects of inbreeding on hatchery and growout performance of the Pacific white shrimp, Penaeus vannamei. The experiment was conducted over 2 yr, and data from two successive generations (G2 and G3) of inbred (sibling,sibling mating) and outbred families were analyzed. There were 11 inbred and 12 outbred families in G2 and 9 inbred and 10 outbred families in G3. Inbreeding coefficients (F) for outbred and inbred families were 0.00 and 0.25, respectively, for G2 and 0.00 and 0.375, respectively, for G3. Growth rates for outbreds and inbreds were similar in both G2 and G3. Hatch rate for inbred families was 33.1% lower than for outbred families in G2 and 47.1% lower in G3. Inbreeding depression (IBD) (relative change in phenotype per 0.1 increase in F) ± 95% CI for hatch rate was ,12.3 ± 10.1%. Hatchery survival for inbred families was 31.4% lower than for outbred families in G2 and 38.8% lower in G3. IBD for hatchery survival was ,11.0 ± 5.7%. Growout survival was 1.9% lower for inbred families than for outbred families in G2 and 19.6% lower in G3. IBD for growout survival was ,3.8 ± 2.9%. There was also a significant linear relationship between IBD estimates for survival traits and mean outbred survival. At high outbred survival, IBD was low (e.g., growout survival in G2), but IBD appeared to become more severe when outbred survival was lower. This suggests that stress (related to environment and/or life stage) may worsen IBD for survival traits. Results also indicate that moderate to high levels of inbreeding (>10%) should be avoided in commercial shrimp hatcheries because the cumulative effect of IBD on hatch rate and hatchery survival will significantly reduce postlarvae production. Thus, IBD can be significant enough to justify the use of inbreeding as a germplasm protection strategy (under certain scenarios) for genetic improvement programs. [source] Spawning of a Captive Population of California Sheephead, Semicossyphus pulcherJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2007Dave Jirsa This study represents the first detailed description of spawning and patterns of egg production in a captive population of California sheephead. In March 2004, females ranged in size from 369 to 430 mm total length (TL) and weighed 0.8,1.5 kg. Males ranged in size from 475 to 510 mm TL and weighed 1.7,2.3 kg. Spawning began in April and continued daily through September and then sporadically through October. Egg production ranged from 1000 to 375,000 eggs/d, with an average of 130,000 eggs/d. Egg production peaked in May at 222,000 eggs/d and decreased throughout the remainder of the season. Total annual fecundity from this group was 1,942,000 eggs/kg female body weight. Egg viability ranged from 0 to 80% with an average of 50%. Viability showed a general increase at the beginning of the season and a decrease at the end of the season. Eggs were 0.9,1.0 mm in diameter and hatched in approximately 48 h at 18,19 C. Hatch rates showed a general decline throughout the season. This study shows that California sheephead will spawn readily in captivity providing thousands of viable eggs daily and lays the groundwork for culture of this species. [source] SEASONAL PERFORMANCE AFFECTING POPULATION DYNAMICS OF CITRUS RED MITE, FANONYCHUS CITRI (MCGREGOR) (ACARI: TETRANYCHIDAE), ON PEARINSECT SCIENCE, Issue 1 2002ZHENG Bo-yi Abstract The population of the citrus red mite, Panonychus citri (McGregor), does not increase on pear from spring to mid-summer but thereafter increases abruptly. To elucidate this phenomenon, we compared the performance of the mites on pear leaves with that on citrus leaves, at different time throughout the pear-growing season. No significant difference was detected between the oviposition rate on pear and that on citrus throughout the season. However, the survival rate of ovipositing females that had fed on pear and the hatch rate of eggs laid by those females were significantly lower than those for females that had fed on citrus, until August. However, no significant difference was observed thereafter. The results showed that the decline of the population of citrus red mite before autumn is due to the high mortality of adult females that had fed on pear leaves and the low hatch rate of the eggs produced by those females. [source] Inbreeding Effects on Hatchery and Growout Performance of Pacific White Shrimp, Penaeus (Litopenaeus) vannameiJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2008Dustin R Moss In animal breeding programs, selection coupled with a narrow genetic base can cause high levels of inbreeding to occur rapidly (in one or two generations). Although the effects of inbreeding have been studied extensively in terrestrial animals and to a lesser extent in aquaculture species, little is known about the effects of inbreeding on penaeid shrimp. The objective of this study was to investigate the effects of inbreeding on hatchery and growout performance of the Pacific white shrimp, Penaeus vannamei. The experiment was conducted over 2 yr, and data from two successive generations (G2 and G3) of inbred (sibling,sibling mating) and outbred families were analyzed. There were 11 inbred and 12 outbred families in G2 and 9 inbred and 10 outbred families in G3. Inbreeding coefficients (F) for outbred and inbred families were 0.00 and 0.25, respectively, for G2 and 0.00 and 0.375, respectively, for G3. Growth rates for outbreds and inbreds were similar in both G2 and G3. Hatch rate for inbred families was 33.1% lower than for outbred families in G2 and 47.1% lower in G3. Inbreeding depression (IBD) (relative change in phenotype per 0.1 increase in F) ± 95% CI for hatch rate was ,12.3 ± 10.1%. Hatchery survival for inbred families was 31.4% lower than for outbred families in G2 and 38.8% lower in G3. IBD for hatchery survival was ,11.0 ± 5.7%. Growout survival was 1.9% lower for inbred families than for outbred families in G2 and 19.6% lower in G3. IBD for growout survival was ,3.8 ± 2.9%. There was also a significant linear relationship between IBD estimates for survival traits and mean outbred survival. At high outbred survival, IBD was low (e.g., growout survival in G2), but IBD appeared to become more severe when outbred survival was lower. This suggests that stress (related to environment and/or life stage) may worsen IBD for survival traits. Results also indicate that moderate to high levels of inbreeding (>10%) should be avoided in commercial shrimp hatcheries because the cumulative effect of IBD on hatch rate and hatchery survival will significantly reduce postlarvae production. Thus, IBD can be significant enough to justify the use of inbreeding as a germplasm protection strategy (under certain scenarios) for genetic improvement programs. [source] Horizontal transfer of the insect growth regulator pyriproxyfen to larval microcosms by gravid Aedes albopictus and Ochlerotatus triseriatus mosquitoes in the laboratoryMEDICAL AND VETERINARY ENTOMOLOGY, Issue 2 2003B. Dell Chism Abstract., The insect growth regulator (IGR) pyriproxyfen is highly active against mosquitoes (Diptera: Culicidae). Through continuous emersion of large larvae (instars 3,4) the concentration causing 50% inhibition of adult emergence (EI50) was determined as 0.200 p.p.b. for Aedes albopictus (Skuse) and 3.5 to 7 times less for Ochlerotatus triseriatus (Say): IE50 0.0288 p.p.b. As a possible method of application to larval microscosms of these species that oviposit in water containers and phytotelmata, the horizontal transfer of pyriproxyfen to larval microcosms by adult mosquitoes was evaluated under laboratory conditions. Gravid females were forced to walk on surfaces treated with pyriproxyfen (tarsal contact exposure) and then allowed to oviposit in larval microcosms. Using replicate bioassay cages, each with an oviposition container, and a factorial experimental design, we assessed Ae. albopictus for the effects of (i) pyriproxyfen concentration (0.2, 0.3 and 0.4 mg/cm2) contacted by gravid females, and (ii) the number of treated gravid females added to bioassay cages (one, three or five females/cage), on the mortality of larvae in oviposition containers. Only 0.2 mg/cm2 treatment rate was tested on Oc. triseriatus. A significant (P < 0.05) curvilinear response in inhibition of emergence (IE) was achieved on both species. Densities of one or three treated Oc. triseriatus females/cage yielded IE rates of only 21,27%, whereas five treated females/cage resulted in 70% inhibition. With Ae. albopictus, densities of three or five treated females/cage yielded 48,67% and 59,73% IE, respectively, whereas one treated female/cage gave only 4,30% inhibition. Use of IGR-treated oviposition containers to achieve horizontal transfer of pyriproxyfen to mosquito oviposition sites could be a field management technique based on mosquito biology and behaviour. In binary choice tests with Ae. albopictus, horizontal transfer of pyriproxyfen from a container with a treated ovistrip (0.3 or 0.4 mg/cm2) to an untreated microcosm resulted in 14,38% inhibition. In larval bioassays, pyriproxyfen activity declined markedly within 10 days. Forcibly exposing gravid female mosquitoes to pyriproxyfen-treated paper surface did not affect their fecundity. However, from the 1st to 2nd gonotrophic cycles the egg hatch rate declined by 30% (P < 0.05). Some variation of results could be due to interactions between females at the oviposition site, possibly causing disproportionate transfer of pyriproxyfen to larval microcosms. Comparative studies of the oviposition behaviour of each mosquito are warranted and would potentially provide information needed to improve the technique. [source] Genetic diversity, but not hatching success, is jointly affected by postglacial colonization and isolation in the threatened frog, Rana latasteiMOLECULAR ECOLOGY, Issue 9 2007GENTILE FRANCESCO FICETOLA Abstract Both postglacial colonization and habitat fragmentation can reduce the genetic diversity of populations, which in turn can affect fitness. However, since these processes occur at different spatial and temporal scales, the consequences of either process may differ. To disentangle the relative role of isolation and postglacial colonization in determining genetic diversity and fitness, we studied microsatellite diversity of 295 individuals from 10 populations and measured the hatch rate of 218 clutches from eight populations of a threatened frog, R. latastei. The populations that were affected by fragmentation to a greater extent suffered higher embryo mortality and reduced hatch rate, while no effects of distance from glacial refugium on hatch rate were detected. Altogether, distance from glacial refugium and isolation explained > 90% of variation in genetic diversity. We found that the genetic diversity was lowest in populations both isolated and far from the glacial refugium, and that distance from refugium seems to have the primary role in determining genetic diversity. The relationship between genetic diversity and hatch rate was not significant. However, the proportion of genetic diversity lost through recent isolation had a significant, negative effect on fitness. It is possible that selection at least partially purged the negative effects of the ancestral loss of genetic diversity. [source] Spermatophore cryopreservation and artificial insemination of black tiger shrimp, Penaeus monodon (Fabricius)AQUACULTURE RESEARCH, Issue 5 2006Amrit N Bart Abstract To develop an appropriate cryopreservation protocol for spermatophores of black tiger shrimp, Penaeus monodon, three cryoprotectants (dimethyl sulphoxide (DMSO), methanol (MeOH) and ethylene glycol (EG)) at two concentrations (5% and 10%) were examined. Artificial implantation of spermatophores was also carried out to assess the fertilizing ability of fresh and post-thaw spermatophores. Spermatophores were collected during consecutive regenerations (15-day intervals) and assessed for qualitative and quantitative changes and also for fertilizing ability by implantation. The mean fertilization rate for artificial insemination using post-thaw spermatophore was 79.9±3.7%, lower than the fertilization rates observed for artificial implantation using fresh spermatophore and natural mating. Mean hatch rates for fresh spermatophore, frozen-thawed spermatophore and natural mating were 88.8±0.6%, 87.8±0.4% and 88.3±0.5%, respectively; and there was no difference among the three groups. The mean fertilization rate of spermatophores collected during the first stripping was higher (90.6±0.6) than during the second stripping (85.7±2.6), but the mean hatch rate was not different between the two strippings. The highest mean sperm viability (79.7±0.4%) was obtained from DMSO (5%), with no survival observed in the 10% MeOH treatment. Spermatophore weight, total sperm count and percentage of abnormal sperm were not different between spermatophores collected at the first and second stripping. This is the first study to report high fertilization and hatch rates from cryopreserved spermatophore using artificial implantation of spermatophore before spawning. [source] Does male secondary sexual trait size reveal fertilization efficiency in Australian Drosophila bipectinata Duda (Diptera: Drosophilidae)?BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2009ARASH RASHED Males developing relatively large, costly sexually selected traits may be of superior body condition compared to small-ornamented males. Thus, males developing the largest secondary sexual trait in a given environment may also be able to augment their investment into ejaculate quality, and fertilize a larger proportion of a female's eggs. We tested the prediction that the degree of expression of a condition-dependent secondary sexual trait, the male sex comb, in a Cape Tribulation (northeastern Australia) population of Drosophila bipectinata Duda, reveals male ability to fertilize eggs in the absence of sperm competition. This test permitted us also to evaluate whether pre-copulatory sexual selection and fertilization efficiency might act additively to influence male reproductive success because a previous study of the same population demonstrated a positive association between comb size and copulation probability. The results obtained indicate that, although genotypes developing smaller sex combs collectively had a significantly higher rate of insemination failure compared to larger comb genotypes, the hatch rate and the number of eggs laid by females inseminated by the two genotypic categories were not statistically different. The results fail to support the prediction that comb size reveals noncompetitive fertilization efficiency of males in this Australian population. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 406,413. [source] Improved Cryopreservation of Sperm of Paddlefish (Polyodon spathula)JOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2006ÁKos Horváth Experiments were performed to improve protocols for sperm cryopreservation of paddlefish (Polyodon spathula), a species for which there has been limited study. The first experiment was conducted to investigate the effects of two extenders (modified Tsvetkova's extender: mT and modified Hanks' balanced salt solution: mHBSS) in combination with methanol (MeOH) and dimethyl sulfoxide in two concentrations (5 and 10%) on the postthaw motility and fertilization rates of cryopreserved sperm. The highest postthaw motility (85 ± 5%) was observed when sperm were frozen using mT extender with 10% MeOH as cryoprotectant. Extenders (P = 0.0018) and cryoprotectants (P = 0.0040) each had a significant effect on the postthaw motility of paddlefish sperm. The highest fertilization (80 ± 3%) was found when eggs were fertilized with sperm frozen with mT extender in combination with 10% MeOH. However, there was no significant difference among fertilization rates when MeOH was used as a cryoprotectant in either concentration or in combination with either mT or mHBSS extenders. In the second experiment, 4000 eggs were fertilized with the pooled contents of five straws of thawed sperm (total volume of 1.25 mL) using mT extender in combination with 5% MeOH, and hatch rates as high as 79 ± 5% were observed. A third experiment was also conducted to clarify the role of MeOH concentration; however, no significant difference was found among fertilization and hatch rates when either 5 or 10% MeOH was used as a cryoprotectant. These results suggest that MeOH is a safe and reliable cryoprotectant for freezing of paddlefish sperm and obtaining viable postthaw sperm for consistent fertilization and hatch rates. Further, this experimental protocol is relatively simple and applicable for commercial hatchery production of paddlefish. [source] Sustained, Natural Spawning of Southern Flounder Paralichthys lethostigma Under an Extended Photothermal RegimeJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2001Wade O. Watanabe Hormone-induced spawning of southern flounder Paralichthys lethostigma has produced substantial numbers of viable eggs, but wide variations in fertilization and hatch rates have been reported. Recently, sustained natural spawning of southern flounder broodstock, without hormone induction, has been achieved in our laboratory. Adults (average weight = 1.12 kg; N= 25), including 6 captured as juveniles in 1993 and 19 captured as adults during September 1998, were stocked in two 4.8-m3 controlled-environment tanks in October 1998 and held under natural photothermal conditions until January 1999, when an artificial winter photo-period of 10 L:14 D was initiated and then maintained through April 1999. Sex ratio was approximately 13 females:8 males:7 unknown. Natural spawning was observed in early December 1998 and increased in frequency to a peak in March 1999, before declining in late April. Water temperature ranged from 13.9 to 24.5 C during the spawning period. Natural spawnings over 142 d produced a total of 18.3 × 106 eggs, with a mean fertilization rate of 28.0% (range = 0,100%), yielding 4.94 × 106 fertilized eggs. The mean percentage of eggs that remained buoyant in full-strength seawater (34 ppt) was 41.3% (0,98%), while hatching rate of buoyant eggs was 37.3% (0,99%) and survival of yolksac larvae to the first-feeding stage was 30.2% (0,100%). Gonadal biopsies in late April identified six females from both tanks as probable spawners. A preliminary comparison suggests that natural spawning produced much larger numbers of viable eggs per female, with higher egg quality (i.e., fertilization and hatching success) than hormone-induced spawning. In contrast to natural spawning, hormone-induced strip-spawning enabled timing of spawnings to be more precisely controlled. These results suggest that a combination of both natural and hormone-induced spawning of photothermally conditioned fish will help produce the large numbers of eggs required to support commercial production. [source] Desiccation tolerance in embryonic stages of the tardigradeJOURNAL OF ZOOLOGY, Issue 1 2008R. O. Schill Abstract Desiccation tolerance commonly found among tardigrades allows them to cope with temporal variation of available water. Although the long-term survival of adults has been demonstrated in several species, desiccation tolerance of eggs and embryos is less well studied, however it is an important aspect from an ecological and evolutionary point of view. For the first time we evaluated the desiccation tolerance and subsequent hatching success of five different developmental stages of the tardigrade species Milnesium tardigradum, when rehydrated following drying at eight different humidity levels (10, 20, 31, 40, 54, 59, 72, 81%). Humidity level and developmental stage are significant factors in determining successful hatch rates. The results showed that the less developed stages were quite sensitive to desiccation. Low humidity levels during the first 3 days of development lead to a decrease in hatch rates following rehydration. Later developmental stages showed higher hatch rates than embryos dried at earlier stages. However, fast drying at low humidity levels resulted in delayed development and lower hatch rates following rehydration. In general, further developed embryos exhibit a better survival capacity compared with younger stages. [source] Spermatophore cryopreservation and artificial insemination of black tiger shrimp, Penaeus monodon (Fabricius)AQUACULTURE RESEARCH, Issue 5 2006Amrit N Bart Abstract To develop an appropriate cryopreservation protocol for spermatophores of black tiger shrimp, Penaeus monodon, three cryoprotectants (dimethyl sulphoxide (DMSO), methanol (MeOH) and ethylene glycol (EG)) at two concentrations (5% and 10%) were examined. Artificial implantation of spermatophores was also carried out to assess the fertilizing ability of fresh and post-thaw spermatophores. Spermatophores were collected during consecutive regenerations (15-day intervals) and assessed for qualitative and quantitative changes and also for fertilizing ability by implantation. The mean fertilization rate for artificial insemination using post-thaw spermatophore was 79.9±3.7%, lower than the fertilization rates observed for artificial implantation using fresh spermatophore and natural mating. Mean hatch rates for fresh spermatophore, frozen-thawed spermatophore and natural mating were 88.8±0.6%, 87.8±0.4% and 88.3±0.5%, respectively; and there was no difference among the three groups. The mean fertilization rate of spermatophores collected during the first stripping was higher (90.6±0.6) than during the second stripping (85.7±2.6), but the mean hatch rate was not different between the two strippings. The highest mean sperm viability (79.7±0.4%) was obtained from DMSO (5%), with no survival observed in the 10% MeOH treatment. Spermatophore weight, total sperm count and percentage of abnormal sperm were not different between spermatophores collected at the first and second stripping. This is the first study to report high fertilization and hatch rates from cryopreserved spermatophore using artificial implantation of spermatophore before spawning. [source] | |||||||||||||