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The effects of dietary supplementation of probiotics on digestive enzymes activities, intestinal morphology and microbiota in juvenile paddlefish (Polyodon spathula) were studied. A total of 400 fish were reared in two cages and fed with a basal diet (control group, CG) or diet supplemented with commercial probiotics (treatment group, TG) for 80 days. Enzymes activities analysis indicated that protease and α-amylase activities increased (P

Reclaimed water is treated wastewater that has received at least secondary treatment and basic disinfection and is reused for beneficial purposes. The goal of this study was to develop a safe and reliable sustainable aquaculture system for producing stocker fish using reclaimed water in decommissioned wastewater treatment plants (WWTP) in Kentucky. The specific objectives were (1) to monitor paddlefish, Polyodon spathula, growth and survival and water quality in experimental tanks with static or flow-through reclaimed water, (2) to evaluate the use of decommissioned tanks for large-scale production of phase II paddlefish, and (3) to biomonitor paddlefish grown in reclaimed water for contaminants. Phase I paddlefish (11 ± 2.6 g) were produced by feeding live Daphnia collected daily from the clarifier tanks with hand-pulled nets for 27 d. Phase II paddlefish were produced in four replicated 5600-L experimental tanks with static and flow-through reclaimed water. Paddlefish from the flow-through system were significantly larger (199.2 ± 61 g) and had better feed conversion ratios (2.8 ± 2.1) than those from the static system (135.5 ± 51 g; 4.1 ± 1.6). For the large-scale trial, two 1125 m3 decommissioned digester tanks were stocked with 50,000 paddlefish larvae per tank. One tank was treated as a flow-through system with reclaimed water flowing at a rate of 280 L/min, while the other tank was treated as a static system where water was just added to replace that lost by evaporation. Survival rate (40%) and weight (194.1 ± 25.4 g) from the flow-through system were significantly different from those of the static system (31%; 147.1 ± 6.5 g). This difference could be linked to better water quality in the flow-through systems. Analyses for 38 contaminants were conducted on Daphnia, prepared diets, and paddlefish. All the concentration levels detected were at levels well below the FDA action limits and their permissible limits in edible food. The result from this project showed that paddlefish can be successfully produced in large-scale as stocker fish using reclaimed water in decommissioned tanks at WWTP.

Summary Experiments were conducted to test the feasibility of using 5-mL straws for the cryopreservation of paddlefish (Polyodon spathula) sperm. In experiment 1, the effects of 5% or 10% methanol as a cryoprotectant in combination with cooling times of 5 or 7 min on paddlefish sperm stored in 5-mL straws were evaluated for fertilization and hatching rates. Highest fertilization rate of 48 ± 5% (mean ± SE) and hatching rate of 47 ± 10% were observed using sperm cryopreserved with 5% methanol and a 5-min cooling time in liquid nitrogen vapors. However, fertilization and hatching rates were significantly lower with cryopreserved sperm than with fresh sperm (fertilization 77 ± 6%; hatching 66 ± 13%). In experiment 2, the effects of sperm : egg ratios on fertilization rates were investigated. When fresh sperm was used, fertilization rate was quadratically related to sperm : egg ratio (y = )13.19x 2 + 55.90x + 38.44, r 2 = 0.823) and the optimum range of sperm : egg ratios was between 1.379 · 10 6 and 2.758 · 10 6 . When sperm were cooled for 5 min with 5% methanol, fertilization rate was linearly related to sperm : egg ratio (y = 22.51x + 23.26, r 2 = 0.75) but optimum sperm : egg ratio was not reached. In experiment 3, the hatching rates were not significantly different between the three-straw treatment and the control. With cryopreserved sperm, the relationship between the sperm and egg ratios and the hatching rates were best described by a quadratic equation (y = )29.65x 2 + 119.2x ) 51.04, r 2 = 0.837). Therefore, when cryopreserved sperm is used, sperm : egg ratio should be increased significantly to optimize fertilization and hatching rates. This can be achieved either by increasing the total volume of cryopreserved sperm by at least 30% or by further research to improve the procedure to increase the viability of post-thawed sperm per straw.

Sex control can solve the problem of stunted black crappie populations in small impoundments. The main objectives of the present study were (1) to identify sex-reversed males of black crappie from a previously obtained androgen-treated group using test crosses, and (2) to develop broodstock of sex-reversed males by masculinization of fish from those crosses. An additional objective of the study was to try to identify sex-specific RAPD markers, which might be used for identification of sex-reversed males. The progenies resulting from test crosses were divided into two groups: Group I (control) fish were raised without hormonal treatment, while Group II fish were subjected to androgen (MT) treatment. Seven progenies were obtained from the cross of preliminary androgen-treated males with normal females. Six of seven progenies had sex ratio in Groups I close to 1:1, and one progeny consisted of females only. This shows that only one male, which generated this progeny, was a sex-reversed homogametic fish (XX) ...

Populations of sturgeon across the globe are threatened due to unregulated harvest and habitat loss, and the status varies among species across North America. Ready access to viable and functional sperm would contribute to recovery programmes for these species. In this study, we examined the motility, viability (cell membrane integrity) of cryopreserved sperm from three North American acipenseriform species and fertilizing capacity. Milt samples were collected from captive shortnose sturgeon (Acipenser brevirostrum), wild paddlefish (Polyodon spathula) and pallid sturgeon (Scaphirhynchus albus) and cryopreserved using combinations of Modified Tsvetkova �s (MT) extender, Original Tsvetkova�s extender, and modified Hanks� balanced salt solution, along with the cryoprotectants methanol (MeOH) or dimethyl sulfoxide (DMSO). A dual-staining technique using the fluorescent stains SYBR-14 and propidium iodide was employed with flow cytometry to determine the percentages of spermatozoa that were viable by virtue of having intact membranes. The percentage of viable spermatozoa ranged from 5% to 12% in shortnose sturgeon, 30–59% in paddlefish, and 44–58% in pallid sturgeon. In the first experiment with shortnose sturgeon sperm, methanol allowed for higher values for dependent variables than did DMSO, and sperm viability generally correlated with post-thaw motility. However, fertilization rate, neurulation, or hatching rates were independent from these factors. In the second experiment with shortnose sturgeon, 5% MeOH combined with MT yielded higher values for all parameters tested than the other combinations: viability was correlated with motility, fertilization rate, and hatching rate. Overall, viability and post-thaw motility was not affected by the use of hyperosmotic extenders (OT) or cryoprotectants (DMSO), but their use decreased fertilization percentages. For paddlefish sperm (experiment 3), MT combined with 10% MeOH was clearly a good choice for cryopreservation; viability and motility results were correlated, but independent of fertilization. For pallid sturgeon sperm (experiment 4), MT with 5–10% MeOH showed significantly higher sperm quality and fertilization parameters. Membrane integrity can be used as a predictor of fertilization by cryopreserved sperm, however additional sperm quality parameters, supplementary to motility and membrane integrity, would be useful in the refining and optimizing cryopreservation protocols with acipenseriform sperm.

— A study was conducted to determine the effect of increasing density on growth and size distribution of paddlefish, Polyodon spathula, juveniles reared in ponds. Feed-trained paddlefish of mean weight (±SE) 25.8 ± 1.1 g were randomly stocked into nine 0.02-ha ponds at 12,355, 18,533, and 24,710 paddlefish/ha, three replications per treatment. The fish were fed daily in excess of what they would eat for 97 d, beginning with a floating trout diet containing 45% protein and 16% lipid and then transferring to a floating catfish diet containing 32% protein and 4.5% lipid. Survival at harvest was not significantly different (P > 0.05) among treatments and averaged 90%. Mean final weights (±SD) for the low-, middle-, and high-density treatments were 205.2 ± 54.1, 174.8 ± 53.2, and 178.6 ± 51.4 g, respectively. Best-fit distributions centered on these means were lognormal. The low-density distribution was significantly different (P 0.05). Paddlefish weight at the minimum target length of 35 cm was estimated to be 100 g by regression analysis. The probability of paddlefish reaching or exceeding 100 g was 90% for the low-density treatment. For the two higher densities, probabilities were 79 and 78%, respectively. Mean Fulton’s condition factors (FCFs) (±SD) were 250 ± 19, 242 ± 4, and 256 ± 37 for the low-, middle-, and high-density treatments, respectively. The FCF for the middle-density treatment was significantly lower than for the low- and high-density treatments (P 0.05). CV, feed conversion ratio, and relative growth were not significantly different (P > 0.05) among treatments and averaged 0.43, 1.50, and 5.45, respectively. Monoculture of paddlefish juveniles in ponds results in a hierarchic size structure when density is at least greater than 12,355 paddlefish/ha. The effect is enhanced with increasing density but becomes asymptotic as density approaches 18,533 paddlefish/ha. Feeding in excess does not ameliorate the effect.

Small-scale fish processing is the likely option available for Kentucky's aquaculture industry where market demand is limited, but the product prices are relatively high in restaurant and retail sectors and the seafood products are exotic and “in demand” by consumers. Paddlefish, a boneless freshwater fish with a meat texture similar to swordfish (Parr, 1999), is such an exotic product that enjoys a limited demand among local restaurant and retailers. This article investigated the optimal management parameters of a small-scale paddlefish processing plant using survey data from Kentucky. In addition, values of economic parameters such as profit, costs, and breakeven price, were also evaluated. Results of this article showed that 939 paddlefish could be processed per day into 1,891 kg of fillets, at a breakeven price of approximately $12.22/kg. Paddlefish steaks were found to be more profitable than fillets only if the steak price exceeded $10.34/kg. At this price, 985 fish could be processed per day into 2...

The germinal epithelium, i.e., the site of germ cell production in males and females, has maintained a constant form and function throughout 500 million years of vertebrate evolution. The distinguishing characteristic of germinal epithelia among all vertebrates, males, and females, is the presence of germ cells among somatic epithelial cells. The somatic epithelial cells, Sertoli cells in males or follicle (granulosa) cells in females, encompass and isolate germ cells. Morphology of all vertebrate germinal epithelia conforms to the standard definition of an epithelium: epithelial cells are interconnected, border a body surface or lumen, are avascular and are supported by a basement membrane. Variation in morphology of gonads, which develop from the germinal epithelium, is correlated with the evolution of reproductive modes. In hagfishes, lampreys, and elasmobranchs, the germinal epithelia of males produce spermatocysts. A major rearrangement of testis morphology diagnoses osteichthyans: the spermatocysts are arranged in tubules or lobules. In protogynous (female to male) sex reversal in teleost fishes, female germinal epithelial cells (prefollicle cells) and oogonia transform into the first male somatic cells (Sertoli cells) and spermatogonia in the developing testis lobules. This common origin of cell types from the germinal epithelium in fishes with protogynous sex reversal supports the homology of Sertoli cells and follicle cells. Spermatogenesis in amphibians develops within spermatocysts in testis lobules. In amniotes vertebrates, the testis is composed of seminiferous tubules wherein spermatogenesis occurs radially. Emerging research indicates that some mammals do not have lifetime determinate fecundity. The fact emerged that germinal epithelia occur in the gonads of all vertebrates examined herein of both sexes and has the same form and function across all vertebrate taxa. Continued study of the form and function of the germinal epithelium in vertebrates will increasingly clarify our understanding of vertebrate reproduction. J. Morphol. 277:1014-1044, 2016. © 2016 Wiley Periodicals, Inc.

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 6 5%) was observed when sperm were frozen using mT extender with 10% MeOH as cryoprotectant. Extenders (P 5 0.0018) and cryoprotectants (P 5 0.0040) each had a significant effect on the postthaw motility of paddlefish sperm. The highest fertilization (80 6 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 mTor 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 mTextender in combination with 5% MeOH, and hatch rates as high as 79 6 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.

Reservoir ranching is an extensive aquaculture practice which stocks young fish that feed on naturally available foods, and are harvested after a period of time. Paddlefish, Polyodon spathulaare filter feeders on zooplankton and are valued for their boneless meat and roe that can be processed into caviar. The goal of this study was to report the perceptions that Kentuckians have of paddlefish reservoir ranching in public waters. Our results show that over 80% of surveyed respondents (N = 478) were in favor of this practice. However, almost 20% of respondents indicated that reservoir ranching of paddlefish might be deleterious for sport fishing in the reservoirs selected for this aquaculture method. A similar proportion of the surveyed sample was against instituting reservoir ranching of paddlefish in public waters. Other results showed that respondent characteristics, such as fishing license ownership and education level, systematically affected their opinion of reservoir ranching. Individuals wi...

Paddlefish (Polyodon spathula) were collected from 4 sites in Kentucky: the Ohio River, Lake Cumberland, and 2 aquaculture sources (private reservoir and catfish ponds). They were tested for methylmer-cury concentrations in their flesh. Paddlefish from all sources had methylmercury levels below the 1 part per million Food and Drug Administration-mandated action limit for seafood. However, using the U.S. Environmental Protection Agency reference dose for methylmercury, only paddlefish from the Ohio River exceeded the reference dose for unrestricted consumption. Some Ohio River and Lake Cumberland paddlefish had higher-than-average methylmercury concentrations, whereas aquacultured paddlefish had low concentrations of methylm-ercury. There was a direct proportionality between fish age and methylmercury concentration; older paddlefish tended to have higher amounts of methylmercury in their meat.

Paddlefish are gaining increasing acceptance as an aquaculture species worldwide. Commercial trout feeds, containing high protein and lipid levels, are currently used in intensive culture; however, nutritional requirements of paddlefish are not currently known. A study was conducted examining the effects on growth, survival and fillet composition of juvenile paddlefish when fed commercial feeds differing in protein and lipid levels. Paddlefish larvae were first stocked in 14.0 m3 round tanks and fed trout starter feeds for 43 days until trained to accept a 1.6 mm pellet. Paddlefish juveniles of mean weight (±SE) 20±0.27 g were randomly stocked into six0.02 ha ponds at 12 500 ha−1 and fed floating commercial trout or catfish (lower protein and lipid) feeds, twice daily (08:00 and 15:30 hours) for 92–97 days. At harvest, there were no significant differences in final weight, percent survival, specific growth rate , relative growth and feed conversion ratio between treatments, which averaged 223.6 g, 96.2%, 2.5% day−1, 10.2 and 1.98 respectively. Surface feeding activity index was significantly higher in ponds supplied with catfish feed than in ponds supplied with trout feeds. Relative pellet buoyancy was not a factor in feeding activity. Fulton's condition factor averaged0.238, was not significantly different, and was similar to a reported value for extensively cultured paddlefish (zooplanktivore). There was no significant difference in liver somatic index between treatments, which averaged 1.91%. Percent protein and moisture of fillets averaged 14.9% and 80.9%, respectively, and were not significantly different between treatments. However, lipid content of fillets was significantly higher in paddlefish fed the trout feed (4.45%), compared with paddlefish fed the catfish feed (2.42%). Fillet lipid content for both treatments was higher than reported values for extensively cultured paddlefish. Percent abdominal fat was significantly higher (0.82%) in paddlefish fed the trout feed compared with paddlefish fed the catfish feed (0.52%). Results from this study indicate that paddlefish can be fed a commercial catfish feed labeled to contain 32% protein and 4.5% lipid without adverse effects on growth, survival and fillet composition, lowering production costs.

We tested the application of mitotic interval (tau [τo]) unit in comparison with absolute time to help standardize preshock timing for a consistent production of diploid meiotic gynogenetic paddlefish Polyodon spathula. The diploid gynogenetic larvae were produced by applying heat shock (35°C; 2 min) at different times after activation of paddlefish eggs with irradiated sperm of shovelnose sturgeon Scaphirhynchus platorynchus at two different preshock temperatures (15°C and 20°C). When the timing of heat shock (minutes after activation) was expressed in absolute time, the yield of gynogenetic diploid larvae was distinctly different between the two preshock incubation temperatures. At 20°C, the highest yield was observed when the timing of the heat shock was 12- 13 min after activation, whereas at 15°C the highest yield was observed when the timing of the heat shock was 17- 22 min after activation. However, when the timing of heat shock was expressed in terms of τo, the yield of gynogenetic diploi...

This study presents data on inheritance of the predorsal black stripe in black crappie Pomoxis nigromaculatus. Four progeny groups, obtained by crossing fish with certain phenotypes and of known origin, were investigated. Presence of the black stripe in all fish in two progeny groups, produced by crossing fish with and without the black stripe, indicated dominance of this trait. In two F2 progeny groups, segregations of fish with: without stripe did not differ significantly from the 3:1 Mendelian ratio. It was concluded from the data that the appearance of predorsal stripe in black crappie is under the control of a dominant mutation of one gene (St/st): fish with genotypes StSt and Stst have a stripe, while fish with genotype stst do not possess this trait. Presence or absence of the black stripe was not connected with sex of the fish. This indicates that gene St/st is located in an autosome but not in a sex chromosome. Distribution of fish with stripe in one F2 progeny group with regard to relat...

The use of hormones is a basic tool for managing reproduction in aquaculture. Delivery of a steroid over an extended period via implantation permits the manipulation of phenotypic sex for some fishes for which administration of the steroid in feed is not an option. An implant fabricated from Silastic materials and filled with 17α-methyltestosterone (MT) has been used to sex-reverse several species of fish. The fish must be large enough to accommodate the implant during the period of gonadal differentiation; the diffusion of 5 mg of MT will take place over a period of about 1 year.

article i nfo A cohort of gynogenote paddlefish was stocked in a 26-ha lake and harvested nine years later. The sex ratio of these mature fish based on gonadal examination indicated that paddlefish female sex determination is het- erogametic rather than the previously reported homogamety. Both sexually mature males and females were present (n=177). The observed sex ratio of 19.8% male: 80.2% female is consistent with the female het- erogamety model and strengthens the emerging pattern in Acipenseriform fishes.

This study investigated the effects of different environmental conditions on the motility parameters of paddlefish (Polyodon spathula) spermatozoa. Paddlefish spermatozoa demonstrated the following characteristics: (i) all spermatozoa were motile 10 s after activation with a velocity of 130-160 microm s(-1); (ii) after 2 min, velocity decreased to 80-130 microm s(-1); and (iii) motility was maintained for up to 9 min. Concentrations of 0.5-5.0 mmol KCl l(-1) prevented activation of spermatozoa. After transfer into a swimming medium (20 mmol Tris l(-1), pH 8.2 and 1 mg BSA ml(-1)) containing 0.5 mmol KCl l(-1) (combined with 5 mmol NaCl or MgCl(2) l(-1)), 80-100% of cells were motile with a velocity of about 120-150 microm s(-1). MgCl(2) significantly improved the velocity of spermatozoa at 10, 40, 50 and 60 s after activation and the stable velocity of spermatozoa was about 140 microm s(-1). Very low concentrations of CaCl(2) (0.125 mmol l(-1)) combined with 0.5 mmol KCl l(-1) initiated motility in 20% of spermatozoa, whereas all spermatozoa were activated after 2 min with 0.25 mmol CaCl(2) l(-1) in similar medium for the full period of swimming with velocity of about 120 microm s(-1). This study demonstrated that potassium (5-15 mmol l(-1)) inhibits demembranated spermatozoa. Thus, initiation of movement in paddlefish spermatozoa is under the reciprocal control of potassium and calcium ion concentrations.

This study reports the results on hormone-induced sex reversal in black crappie Pomoxis nigromaculatus and the sex ratios of progenies obtained from test crosses of androgen-treated males with normal females. The androgen 17α-methyltestosterone (MT) was orally administered to fish with an artificial diet (30 mg/kg) for 30 d beginning 37 d after hatching; mean fish lengths were 35 and 55 mm at the beginning and conclusion of the treatment, respectively. The MT-treated group consisted of 95% males and 5% intersex fish, while the sex ratio in the control group was not significantly different from 1:1. Four males from the androgen-treated group were individually test-crossed with normal females to identify sex-reversed males according to the sex ratios in progenies and to reveal the chromosomal mechanism of sex determination in black crappie. Two out of three analyzed progenies consisted of females only, while one progeny had a sex ratio not significantly different from 1:1. The appearance of all-fem...

Paddlefish are endemic to most rivers and tributaries of the Mississippi basin and are found in 22 states of the United States. In 1989, US Fish and Wildlife Service (USFWS) listed paddlefish as a category 2 species because data were lacking on its population status. In 1992, USFWS added paddlefish to the list of Appendix II of the Convention on International trade in Endangered Species of Wild Fauna and Flora (CITES) primarily due to concerns about illegal poaching in the international caviar trade. Therefore, paddlefish aquaculture will provide alternative fish sources for the marketplace in the era of strict federal and state regulations on wild populations. Aquaculture of paddlefish is in a research and developmental phase. Most broodstock are obtained from wild sources, though some mature fish have been developed in captivity. Artificial propagation techniques are resulting in > 80 % egg fertility. Larval paddlefish are initially raised in organically fertilized, zooplankton-rich (i.e. Daphnia sp.) ponds, and then trained on extruded trout/salmon diets until the juvenile fish are > 30 cm in total length. Tank culture is also an alternative for raising juvenile fish. Juvenile paddlefish, a filter feeder that requires zooplankton as its primary food, are being grown in reservoirs and in polyculture with channel catfish (Ictalurus punctatus) in Kentucky, Indiana, Missouri and Alabama. Production yields are 200–400 kg·ha–1 in polyculture and in reservoirs ranching resulted in 55–175 kg·ha–1. Reservoir ranching is ideal for caviar production; whereas, paddlefish (1.5 to 4.0 kg) cultured with catfish is for meat production. A system to produce all-female progeny through artificial propagation with sex-inverted, gynogenetic broodstock and attempting to develop optimal cryopreservation techniques for the milt of these unique broodstock is currently being tested. Value-added products such as hot and cold smoked paddlefish are the major effort being developed for the marketplace. Consumer acceptability of value-added products from paddlefish has been better than channel catfish.

Paddlefish Polyodon spathula (30–67 cm total length, TL) were stocked in six flood control reservoirs (

The objective of this study was to determine the composition and the physicochemical properties of paddlefish meat under refrigerated (0°C) and frozen (-29°C) storage. Paddlefish meat contained 79.0% moisture, 17.5% protein, 3.1% fat, and 1.0% ash. Under refrigerated storage, protein solubility and shear force of the meat decreased after 3 days, whereas TBARS increased from 4.5 to 8.0 nmole/g meat after 7 days. During frozen storage, protein solubility decreased by 20% at the beginning and continued to decline during the first 5 months, while shear force declined after 3 months and TBARS increased from 5.0 to 7.8 nmole/g meat only after 5 months (p < 0.05). There was no significant degradation of myosin during refrigerated storage. In addition, neither refrigerated nor frozen storage significantly altered the thermal stability of the muscle proteins.

An extract from paddlefish surimi possessed activities of B, L, and H-like cathepsins. The optimal pH was around 5.0 for cathepsins B and L, and was between 6.0-6.5 for the H-like cathepsin. The enzyme activities were not impaired by heating at 40C for 20 min. However, the protease extract lost about 20% of its cathepsin B, 50% B+L, and 90% H-like cathepsin activities after heating at 50C for 20 min. The activity of H-like cathepsin was not inhibited by E-64, suggesting that it did not belong to the known cysteine protease group. The protease extract was capable of hydrolyzing myosin heavy chain, producing a major fragment(s) around 140 kDa. Degradation of myosin by the protease extract was substantially reduced by protease inhibitors including E-64, a protease inhibitor mixture, and bovine plasma powder.

Ninety to 100% of paddlefish Polyodon spathula were motile just after transfer into distilled water, with a velocity of 175 μm s -1 , a flagellar beat frequency of 50 Hz and motility lasting 4-6 min. Similarly, 80-95% of shovelnose sturgeon Scaphirhynchus platorynchus spermatozoa were motile immediately when diluted in distilled water, with a velocity of 200 μm s -1 , a flagellar beat frequency of 48 Hz and a period of motility of 2-3 min. In both species, after sperm dilution in a swimming solution composed of 20 mM Tris-HCl (pH 8.2) and 20 mM NaCl, a majority of the samples showed 100% motility of spermatozoa with flagella beat-frequency of 50 Hz within the 5 s following activation and a higher velocity than in distilled water. In such a swimming medium, the time of motility was prolonged up to 9 min for paddlefish and 5 min for sturgeon and a lower proportion of sperm cells had damage such as blebs of the flagellar membrane or curling of the flagellar tip, compared with those in distilled water. The shape of the flagellar waves changed during the motility phase, mostly through a restriction at the part of the flagellum most proximal to the head. A rotational movement of whole cells was observed for spermatozoa of both species. There were significant differences in velocity of spermatozoa between swimming media and distilled water and between paddlefish and shovelnose sturgeon.

Gelation properties of paddlefish surimi were investigated with different heating procedures. Without pre-incubation, gel strength of paddlefish surimi increased as temperature increased from 40 to 60 °C. Pre-incubation at 40 °C caused myosin degradation and reduced gel strength by 55% compared to the control. Pre-incubation at 70 °C followed by cooking at 90 °C produced gels with maximum strength. Isothermal heating between 40 and 50 °C produced rheological transitions between 0 and 15 min. Beef plasma powder reduced myosin degradation and enhanced gelation of surimi incubated around 40 °C. These results indicated that the gel-weakening phenomenon in paddlefish surimi was due to the degradation of myosin by some endogenous protease(s).

This study reports the results of initial experiments on induced diploid gynogenesis in black crappie Pomoxis nigromaculatus. White bass Morone chrysops were an effective sperm donor for gynogenetic experiments with black crappies. White bass spermatozoa fertilized black crappie eggs, but hybrid larvae were not viable and died after hatching. In a series of experiments, we determined the ultraviolet (UV) light dose required to inactivate the sperm genome and the heat shock parameters needed to restore diploidy. Black crappie eggs were inseminated with white bass sperm irradiated with UV dosages ranging from 25 to 2,500 J/m2. A typical “Hertwig effect” in the yield of hatched larvae was observed with dosages greater than 100 J/m2. The genetic inactivation of paternal chromosomes was confirmed by flow cytometry measurement of DNA content in larval cells. Larvae resulting from sperm irradiated at a dose of 1,000 J/m2 were haploid. Time durations of mitotic interval (τ0) at different temperatures for...

— A practical procedure for cryopreserving milt of paddlefish Polyodon sparhula was developed to obtain thawed spermatozoa that would fertilize eggs and permit hatching of normal larvae. Milt was mixed with a cryoprotectant medium containing DMSO (2.4 M) in a ratio of 3:1(milt: medium; final concentration of DMSO 0.6 M), stored in 5.0-mL freezing straws, and frozen in dry ice (15 min) and then in liquid nitrogen. A total of three replicates were made; the milt of a different male was used in each replicate. Motility of the thawed spermatozoa decreased to 50%-25% as compared to 100% motility of the fresh (control) spermatozoa. Hatching of paddlefish (16.3 ± 2.2%) from eggs fertilized with thawed spermatozoa was significantly lower (P≤ 0.01) than the hatch rate (90.8 ± 2.5%) for the control. It was suggested that an increase in viable motile spermatozoa to egg would result in better fertilization and hatching of paddlefish.

LUDEǨ STĚCH, OTOMAR LINHART*, WILLIAM L. SHELTON and STEVEN D. MIMS Fish Culture Hluboka nad Vltavou, Tyrsova 681, 373 41 Hluboka nad Vltavou, Czech Republic; Research Institute of Fish Culture and Hydrobiology, University of South Bohemia, 389 25 Vodňany, Czech Republic; Zoology Department, University of Oklahoma, Norman, Oklahoma 73019, USA; Aquaculture Research Center, Kentucky State University, Frankfort, Kentucky 40601, USA

Gynogenesis was induced in three shovelnose sturgeon (Scaphirhynchus pIatorynchus) by heat shock after egg activation with UV-treated paddlefish (Polyodon spathula) milt. Ultraviolet dosage (J m−2) for the pooled milt samples was calculated using the following linear regression equation: Dosage = 2405.27 − 352.80X 19.78X2 (X = percent transmittance of milt). Activated eggs were incubated at 18 °C until shocking at 35 °C. Shock duration was applied at 0.05τ0 intervals from 0.15 to 0.40 τ0 (8.25 to 22.00 min post-fertilization; τ0 at 18 °C = 55 min). The highest yield of gynogenotes (16%) was observed at 0.25 τ0 for female 3, 10 % at 0.30 τ0 for female 2 and 12% at 0.35 τ0 for female 1. The percentage of viable gynogenotes responded quadratically to the tau index (τs/τ0) when shock treatments were applied. The higher yields of viable diploid sturgeon gynogenotes were achieved when eggs were heat shocked at embryological ages ranging from 0.25 to 0.35 τ0 (approximately 14 to 19 min post-activation at 18 °C). No viable hybrids were produced in the control fertilization of sturgeon eggs with intact paddlefish sperm which verified the gynogenetic origin of the offspring produced. © Rapid Science Ltd. 1998

Viable, diploid gynogenetic (gynogenotes) paddlefish Polyodon spathula were produced by activating eggs with ultraviolet-irradiated shovelnose sturgeon Scaphirhynchus platorynchus spermatozoa and heat shocking. Without irradiation treatment, sturgeon spermatozoa appeared to activate the eggs (up to gastrulation), but did not result in any viable hybrids. Experiment 1 determined that heat-shock treatment of 35 C for a 2-min duration within the interval of 2–22 min post-activation resulted in highest yield of gynogenotes (12–19%) from eggs incubated at 18 C. Experiment 2 applied the heat shock treatment at 35 C from 14.0 to 28.0 min in 2-min intervals after activation at 18 C for a larger scale of gynogenetic production. Both experiments showed that the best yields of gynogenotes were obtained when the heat shock treatment occurred at 16, 18, and 20 min after activation. When these times were expressed in terms of τ0. units (duration of one mitotic cycle of synchronous cell division related to water temperatures), optimal activations were 0.26, 0.29, and 0.32τ0 (τ0@ 18 C = 63.5 min). Experiment 3 tested the utility of τ0. at two different pre-shock incubation water temperatures of 18 C and 16 C, and determined that there was no significant interaction in percentage of viable gynogenotes between two different incubation temperatures and the mitotic intervals (0.21, 0.26, 0.31, 0.36, 0.41τ0) tested. Best survival of gynogenotes occurred when eggs held at either pre-shock incubation water temperatures were shocked at 0.26τ0 All gynogenotes examined were histologically confirmed to have ovarian tissue and were determined to have similar oocyte development to that of normal female (control) paddlefish.

A temperature-dependent measure of the mitotic interval (τ0) can help standardize chromosome manipulation in fish eggs. A tau unit (τ0) is the duration in minutes of one mitotic cycle during synchronous embryonic cleavage. It is measured over a range of temperatures, and the resulting relationship of τ0 to temperature can be used to anticipiate developmental events that are affected by temperature. Optimum induction of chromosome manipulation requires development of a specific treatment of egg shocking for each species, Timing of shock is a critical variable, but pretreatment incubation temperature affects the rate of development and thus the optimum absolute time for shocking. Mitotic intervals (τ0) are reliable indicators of developmental rates over normal temperatures for egg incubation, and thus can be used to estimate optimal times for chromosome manipulation, Mitotic intervals for paddlefish Polyodon spathula and shovelnose sturgeon Scaphirhynchus platorynchus were estimated by averaging th...

Blue catfish (Ictalurus furcatus) juveniles (59 g) and channel cafish (I. punctatus) juveniles (84 g) were stocked at 24,700 fish/ha into twelve 0.04-ha earthen ponds and fed diets containing either 25 or 35% protein according to a winter feeding schedule. After 189 days, final biomass in ponds stocked with channel catfish was significantly greater (P < 0.05) than in ponds stocked with blue catfish, largely reflecting differences in stocking weight. Both species lost weight during the winter period, whether fed 25 or 35% protein diets. At harvest, fat levels were significantly higher and protein levels significantly lower in blue catfish than in channel catfish, despite the blue catfish's smaller size. Channel catfish appear to rely more on fat stores during the winter period than blue catfish. Blue catfish demonstrated no growth advantage over channel catfish during the winter period.

A minimally invasive surgical technique (MIST) for the removal of ovulated eggs from paddlefish Polyodon spathula was tested on broodstock that had been previously spawned using MIST to determine whether repeat spawning affected fecundity or hatching rate compared with broodstock than had not previously been induced to spawn. There were no significant differences in the number of eggs removed or in the hatching rate between first- and second-time MIST spawners. The oviducts from second-time MIST spawners appeared normal and had no scarring or blockage. The MIST approach is efficient, practical, and less stressful to broodstock during artificial propagation than other reported egg collection procedures.

Food selection of larval paddlefish Polyodon spathula was evaluated by gut analysis in nine 0.02-ha ponds either fertilized with rice bran (RB) to promote zooplankton production, supplied with prepared diets (PD), or with a combination of rice bran and prepared diet (CB). After 40 d, mean fish yields in RB and CB ponds were significantly higher (P 0.05) in survival among treatments. Cladocerans were the main Live food items selected by paddlefish in RB and CB ponds. Chironomid larvae were the main food items selected by paddlefish in PD ponds. Less than 10% of the food found in paddlefish guts was prepared diets in PD and CB ponds. Prepared diets apparently were not as available to the fish or were not as preferred by the fish as Live foods. Levels of un-ionized ammonia were significantly greater in CB and PD ponds than that in RB ponds. Decomposition of uneaten high-protein diets in PD and CB ponds probably led to production of ammonia. Elevated un-ionized ammonia levels during week 5 caused abnormal swimming behavior and some paddlefish mortalities in PD and CB ponds. Based upon these results, use of RB or other organic fertilizers to promote zooplankton production is recommended over direct feeding or a combination of fertilization and feeding for larval paddlefish in earthen ponds.

The spermatozoa in the seminal plasma from shovelnose sturgeon Scaphirhynchus platorynchus and paddlefish Polyodon spathula were immotile with only a few spontaneously motile spermatozoa for 5-10 and 10-20 s, respectively. Spermatozoa of shovelnose sturgeon were observed to be 100% motile immediately after sperm dilution in 10 mm NaCl and 20 mm Tris-HCl, pH 8.5. The duration of mass progressive movement was 2-3 min; and 1 to 5% of spermatozoa remain active after 360 s (P

Channel catfish, Ictalurus punctatus, swim-up fry were either stocked directly into prepared nursery ponds or fed a prepared diet in hatchery tanks for seven days prior to stocking in ponds to evaluate the effects of hatchery feeding on growth and survival in ponds. Two experiments were conducted during two growing seasons (1991 and 1992). Nursery ponds in both treatments were prepared and fertilized according to standard recommended procedures. Survival was significantly higher (P 0.05) in average weight between treatments in either experiment. In experiment 1, total yield was significantly higher (P 0.05) in feed conversion ratio (FCR) in experiment 1. During experiment 2, FCR was significantly lower (P < 0.05) in fish not fed prior to stocking. Results indicate that stocking of channel catfish ...

Milt samples from paddlefish (Polyodon spathula) were collected from specimens obtained from the Missouri River near Chamberland, South Dakota, in 1991 and the Opelika City Reservoir System near Auburn, Alabama, in 1992. Ice-chilled milt samples either were left undiluted or were diluted with one of three chilled extenders, transported overnight on ice, and analyzed for sperm concentration, extracellular pH, electron microscopical characters, sperm motility percentage, and duration of sperm motility. Paddlefish milt had relatively low sperm counts compared with milt of other fish species, averaging 1.8 × 109 spermatozoa/mL. Extracellular pH averaged 8.22. A sperm acrosome was demonstrated by electron microscopy. Dechlorinated tap water and 10% artificial sea water (ASW) activated and sustained sperm motility better than 25% ASW Transportation of milt had no apparent negative effect on fertility. For storage 1–5 d after collection, undiluted milt provided an average fertilization rate (93%) that w...

In the present study was summarize the factors activating and/or inhibiting the motility of intact and/or demembranated spermatozoa of common carp and paddlefish as teleostean and chondrostean models using methods of sperm demembranation. The movement of spermatozoa of cyprinids species, common carp, is influenced by osmotic pressure or high concentration of ions. The movements of spermatozoa of chrondrostean species, paddlefish, are under reciprocal control by the concentration of K+ and Ca2+.

Two agro-industrial by-products, rice bran (RB) and distillers dried solubles (DS), and a prepared diet (PD) were evaluated as organic fertilizers for the production of juvenile paddlefish in nine 0.02-ha earthen ponds over a 40-day culture period. Paddlefish yield from ponds fertilized with RB (209 kg/ha) was significantly greater (P≤0.05) than that from ponds fertilized with DS (129 kg/ha), but it was not significantly greater than yields from ponds fertilized with PD (258 kg/ha). Fish survival from ponds fertilized with PD (79%) was significantly higher than from ponds fertilized with RB (55%) or DS (50%). There was no significant difference in survival between ponds fertilized with RB and DS. Secchi disk visibilities in ponds fertilized with RB were significantly lower than in ponds fertilized with DS and PD. Relatively low Secchi disk visibilities in RB-fertilized ponds were because of a brown stain or coloration which reduced sunlight penetrationa and growth of filamentous algai, not observed in Ds-...