Steven D. Mims

A Temperature-Dependent Index of Mitotic Interval (τ0) for Chromosome Manipulation in Paddlefish and Shovelnose Sturgeon

Abstract 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...

Storage, Transportation, and Fertility of Undiluted and Diluted Paddlefish Milt

Abstract 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...

Effects of ions on the motility of fresh and demembranate spermatozoa of common carp (Cyprinus carpio) and paddlefish (Polyodon spathula)

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+.

Induced gynogenesis in black crappie.

Abstract 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...

Minimally Invasive Surgical Removal of Ovulated Eggs from 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

A Comparison of Second-Year Growth of Blue Catfish and Channel Catfish in Kentucky

Abstract Second-year growths of blue catfish (Ictalurus furcatus) and channel catfish (I. punctatus) were compared in north-central Kentucky. Percent weight gain was significantly higher (P 0.05) in feed conversion or survival. Blue catfish showed more consistent growth and were easier to seine than were channel catfish. Blue catfish should be evaluated further in temperate regions.

Induced meiotic gynogenesis in shovelnose sturgeon

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.

Evaluation of three organic fertilizers for paddlefish,Polyodon spathula, production in nursery ponds

Abstract Organic fertilization of paddlefish ( Polyodon spathula ) nursery ponds with rice bran (RB), distillers dry grain (DG) or cottonseed meal (CSM) was evaluated in nine 0.02-ha ponds over a 40-d period. Net yields (kg/ha) and growth rate of fish in ponds fertilized with RB were significantly higher (P ≤ 0.05) than with CSM, but not significantly different (P > 0.05) in ponds fertilized with DG. There was no significant difference (P > 0.05) in fish survival (RB 77%, DG 79%, and CSM 65%) for ponds receiving any of the three fertilizers. Secchi disk visibility and dissolved oxygen were significantly lower (P ≤ 0.05) in ponds fertilized with RB than in ponds fertilized with CSM and DG. Ammonia and nitrite levels differed only during week 3 and were significantly higher (P ≤ 0.05) in ponds fertilized with CSM and DG than in ponds fertilized with RB. Large cladocerans ( Daphnia, Simocephalas, Scaphaleberis ) were the dominant food items found in stomachs of fish in all treatments. RB proved to be superior to CS and DG as an organic fertilizer for paddlefish nursery ponds when evaluated in terms of fingerling growth, water quality, and zooplankton production.

Hormonal Sex Reversal and Evidence of Female Homogamety in Black Crappie

Abstract 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...

Reservoir Ranching of Paddlefish

Abstract Paddlefish Polyodon spathula (30–67 cm total length, TL) were stocked in six flood control reservoirs (<41 ha) in western Kentucky in January 1995 at a target stocking density of 10 fish/ha. Fish growth was monitored quarterly beginning in July 1995. The fish were implanted intraperitoneally with passive integrated transponder (PIT) tags. Chemical and physical variables and zooplankton biomass were measured monthly. Three reservoirs that had not been stocked were sampled monthly as controls. Of the 1,440 paddlefish stocked, 353 were recovered at harvest in the fall of 1996, and only two tags were found. Anecdotal evidence indicated some loss to predation by largemouth bass Micropterus salmoides and some to escapes through mechanical spillways. The total gross yield was 1,715 kg or 13.7 kg/ha; it ranged from 0.6 to 28.8 kg/ha. Gill nets of 102-mm-bar mesh were optimum for harvest. Mean harvest weights were significantly different among reservoirs. A positive correlation was found between relative ...