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Cryopreservation can preserve genetic materials in perpetuity and can be applied to oyster culture for breeding programs. Protocols exist for sperm cryopreservation in the eastern oyster Crassostrea virginica, but nonlethal sample collection is needed for valuable individuals, such as tetraploids, or specific lines. The goal of this study was to develop nonlethal methods for sperm collection in the eastern oyster. The objectives were (1) to evaluate natural spawning as a collection method, (2) to evaluate anesthesia methods to induce shell opening for biopsy, (3) to evaluate mechanical notching for biopsy, and (4) to verify notching combined with biopsy for collection and cryopreservation. Five males (of 60 oysters) spawned naturally alter 7 h, with an average sperm concentration of 1.9 ± 1.0 ×103 cells/mL (in 2 L seawater). No oysters (n = 30) responded by opening during 36 h of treatment with 5% Dead Sea salt (containing 33.3% MgCl2), and 22 oysters (of 30) opened during the 36-h treatment with 5% Epson salt (MgSO4). Sperm collected by biopsy had fresh motility of 3%-80% and postthaw motility of 1%-5%; sperm production was 4.5 × 105 to 2.3 × 108 cells per male. Mechanical notching did not cause mortality to oysters (n = 20). After notching and biopsy with 18-G and 20-G needles, survival was 80% (16 of 20 for each). Sperm production was 5.42 × l07 cells by 18-G needle (n = 8) with fresh motility of 16 ± 12% and postthaw motility of 3 ± 2%, and 1.35 × 108 cells by 20-G needle (n = 9) with fresh motility of 21 ± 20% and postthaw motility of 5 ± 4%. No differences were observed between samples biopsied with the 2 needle sizes (P ⩾ 0.074). To verify notching and biopsy for nonlethal sperm collection, a total of 39 oysters were sampled to obtain 20 males, which averaged 99.48 ± 23.17 g total weight, 74.1 ± 6.0mm shell height, and 60.9 ± 7.2mm shell length. The sperm production was 3.6 ± 2.1 × 108 cells per male. Biopsied sperm showed 23 ± 12% fresh motility, 13 ± 6% postequilibration motility (after equilibration with 10% of DMSO for 30-60 mm before freezing), and 6 ± 4% postthaw motility. Flow cytometry analysis indicated an average of 84 ± 4% of cells with intact plasma membranes for fresh sperm, and 59 ± 9% for postthaw sperm. Fertilization by thawed sperm averaged 20 ± 22% (from 1 %-87%). No significant differences were observed between the biopsied samples and the dissected samples (lethal collection) for fresh motility (P = 0.550), postequilibration motility (P = 1.000), postthaw motility (P = 0.101), fresh membrane integrity (P = 1.000), or postthaw membrane integrity (P = 1.000), but a difference was observed in fertilization (P = 0.039; biopsied samples, 20 ± 22%; dissected samples, 68 ± 40%). Overall, this study developed notching combined with biopsy for sperm collection and cryopreservation in Eastern oysters that can be applied to valuable individuals and breeding programs. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine whether the current consumer method of boiling shrimp until floating and pink in color is adequate for destroying Listeriaand Salmonella. Shrimp samples were submerged in bacterial suspensions of Listeriaand Salmonellafor 30 min and allowed to air dry for 1 h under a biosafety cabinet. Color parameters were then measured with a spectrophotometer programmed with the CIELAB system. Twenty-four shrimp samples were divided into groups (days 0, 1, or 2) and stored at 4°C. The samples were treated by placing them in boiling water (100°C) on days 0, 1, and 2. The shrimp were immediately removed from the boiling water once they floated to the surface, and color parameters were measured. Bacterial counts were determined, and the log CFU per gram was calculated. The effect of sodium tripolyphosphate on the color change of cooked shrimp also was determined. Initial bacterial counts on shrimp after air drying were 5.31 ± 0.14 log CFU/g for SalmonellaEnteritidis, 5.24 ± 0.31 log CFU/g for SalmonellaInfantis, 5.40 ± 0.16 log CFU/g for SalmonellaTyphimurium, 3.91 + 0.11 log CFU/g for Listeria innocua, 4.45 ± 0.11 log CFU/g for Listeria monocytogenes(1/2a), and 3.70 ± 0.22 log CFU/g for Listeria welshimeri.On days 0, 1, and 2, all bacterial counts were reduced to nondetectable levels for shrimp samples that floated. The average time for shrimp to float was 96 ± 8 s. The bacterial counts remained at nondetectable levels (<10 log CFU/g) during refrigerated (4°C) storage of cooked shrimp for 2 days. The redness, yellowness, and lightness were significantly higher (P< 0.0001) for the cooked shrimp than for the uncooked shrimp on all days tested. The standard deviation for redness in the cooked shrimp was large, indicating a wide range of pink coloration on all days tested. The results suggest that boiling shrimp until they float will significantly reduce Listeriaand Salmonellacontamination, but color change is not a good indication of reduction of these pathogens because of the wide natural color variation.

The focus of this research was to investigate the efficacy of icing as a postharvest treatment for reduction of the levels of Vibrio vulnificusand Vibrio parahaemolyticusin commercial quantities of shellstock oysters. The experiments were conducted in June and August of 2006 and consisted of the following treatments: (i) on-board icing immediately after harvest; (ii) dockside icing approximately 1 to 2 h prior to shipment; and (iii) no icing (control). Changes in the levels of pathogenic Vibriospp. during wholesale and retail handling for 2 weeks postharvest were also monitored. On-board icing achieved temperature reductions in all sacks in accordance with the National Shellfish Sanitation Program standard, but dockside icing did not meet this standard. Based on one-way analysis of variance, the only statistically significant relationship between Vibriolevels and treatment occurred for samples harvested in August; in this case, the levels of V. vulnificusin the noniced oysters were significantly higher (P< 0.05) than were the levels in the samples iced on-board. When analyzing counts over the 14-day storage period, using factorial analysis, there were statistically significant differences in V. vulnificusand V. parahaemolyticuslevels by sample date and/or treatment (P< 0.05), but these relationships were not consistent. Treated (iced) oysters had significantly higher gaping (approximately 20%) after 1 week in cold storage than did noniced oysters (approximately 10%) and gaping increased significantly by day 14 of commercial storage. On-board and dockside icing did not predictably reduce the levels of V. vulnificusor V. parahaemolyticusin oysters, and icing negatively impacted oyster survival during subsequent cold storage.

Oysters held near-shore in Caminada Bay, Louisiana during the summer, exhibit hypertrophic gonads with prominent genital canals beneath transparent mantle tissue about four weeks post-hatchery spawning, indicating recycling. Broodstock (N = 200) were analyzed histologically over a two-year period to document such gametogenesis, using Gonad/Body Ratios (GBR) and (level- opmental stages. Ten oysters were randomly selected from a broodstock pool prior to each spawning attempt. and monthly during the winter-spring. As expected, the mean GBR before successful spawning attempts was significantly greater (P ≤ 0.05) than the mean GBR before unsuccessful attempts. A dramatic drop in the percent occurrence of the advanced spawning and regression stage from May to June, a >40% spawning stage occurrence from May to October, and fluctuations in the percent occurrence of early and late developmental stages during the summer months illustrates gonadal recycling. [ABSTRACT FROM AUTHOR]

Experimental plots were established at a relic oyster reef on the eastern side of Mobile Bay, Alabama between July 1998 and November 1999 to determine whether elevated beds might improve oyster survival and growth. Oysters (Crassostrea virginica) were spawned in a hatchery and the spat were allowed to settle on small oyster shell fragments and on whole oyster shell. Two- month-old juveniles (15-18 mm) were deployed in polyethylene oyster bags on bottom and on underwater shell pads 20 cm and 40 cm above bottom. Oysters on whole shells were deployed outside bags in order to evaluate predation. Remote sensing data loggers were deployed near bottom and 40 cm above bottom to measure temperature, salinity, and oxygen concentration. Growth (increase in height), survival, and condition of oysters in bags at the three experimental depths were compared. Temperature and salinity varied between 11.8 °C-32.8 °C and 4.4 ppt-29.7 ppt, respectively. Periodic anoxic events, which lasted from a few hours to 6 days, were documented. Oysters at the three experimental levels grew to approximately 55 mm during the first year. Total mortality was observed at all three levels during the second summer when oxygen levels dropped to 0 mg L-1 for five consecutive days while water temperature was 28 °C. If the 17 months monitored during this study are typical, restoration of Fish River Reef will be difficult due to periodic anoxic events. [ABSTRACT FROM AUTHOR]

Provides information on a study which discussed the Gulf Oyster Industry Program of the Louisiana Sea Grant College Program. Motive for the creation of the program; Goals that have complicated the implementation of the program; Factors associated with the problems faced by oyster producers in the Gulf states.

Investigates the effect of Cytochalasin B on survival and triploidy induction in Crassostrea virginica larvae. Preparation of gametes; Details of fertilization and treatment; Method used for determining differences among treatment means for survival and percentage triploidy.