Nick C. Parker

Physiological stress in striped bass : effect of acclimation temperature

Abstract Physiological responses to acclimation temperature and confinement stress were studied in yearling striped bass, Morone saxatilis . Temperature significantly affected plasma cortisol, glucose, chloride, and hematocrit but not osmolality in fish acclimated to 5, 10, 16, 21, 25 and 30°C. Close confinement for 12 min in a net resulted in changes of these characteristics in some or all of these groups. Generally, plasma cortisol and glucose increased, and plasma chloride, osmolality, and hematocrit decreased due to net confinement, and returned toward resting levels after release from the net. The physiological changes during stress were greatest and the recovery from these changes was slowest at 5 and 30°C. Further, the quantitative response was least and the recovery most rapid in fish stressed at 10 and 16°C. Acclimating and moving striped bass within this temperature range should decrease stress-related responses and mortality and thus improve yield after stocking.

Influence of Water Hardness and Salts on Survival and Physiological Characteristics of Striped Bass during and after Transport

Abstract Physiological characteristics and survival of striped bass Morone saxatilis were evaluated during, and for 1 month after, transportation from a soft-water hatchery (hardness, 28 mg/ L) to a hard-water hatchery (hardness, 110 mg/L). Fish were transported and allowed to recover in either 1.0% sodium chloride, 0.1 % calcium chloride, or fresh water. The addition of 1.0% sodium chloride to the transportation and recovery waters increased survival, decreased the rise in plasma cortisol and plasma glucose concentrations, and reduced osmoregulatory dysfunction. The addition of 0.1% calcium chloride to the transport and recovery media or the use of fresh water did not significantly reduce the stress response of striped bass during and after transport. Striped bass had significantly better survival and lower stress response when transported and allowed to recover in 1.0% sodium chloride than when treated in fresh water or 0.1 % calcium chloride, which is generally used in soft-water hatcheries to increase...

Plasma Corticosteroid Stress Response of Fourteen Species of Warmwater Fish to Transportation

Abstract Plasma corticosteroid concentrations were measured in 14 species of fish immediately after they were electrofished from reservoirs on the Alabama River and after they had been transported for 2 h. There was no corticosteroid response in spotted gars Lepisosteus oculatus. Bowfins Amia calva, longnose gars Lepisosteus osseus, and freshwater drums Aplodinotus grunniens had only small corticosteroid increases (14–39 ng/mL) during transportation. Corticosteroids increased by intermediate amounts (59–184 ng/mL) during transportation in blue catfish Ictalurus furcatus, paddlefish Polyodon spathula, largemouth bass Micropterus salmoides, channel catfish Ictalurus punctatus, river carpsuckers Carpiodes carpio, white bass Morone chrysops, striped bass Morone saxatilis, and crappies Pomoxis sp. The greatest increases were 223 ng/mL in gizzard shad Dorosoma cepedianum and 286 ng/mL in common carp Cyprinus carpio. Spotted and longnose gars, largemouth bass, and common carp also were held in tanks for about 2 ...

Hormonal sex manipulation and evidence for female homogamety in channel catfish

The mechanism of sex determination in channel catfish Ictalurus punctatus was evaluated by hormonal and genetic methods. Aromatizable and nonaromatizable androgens, as well as an estrogen, caused feminization in fish fed steroids for 21 days after yolk-sac absorption. The effectiveness of 60 micrograms of ethynyltestosterone/g food decreased markedly when the experimental feeding period was shortened and was ineffective when the treatment lasted less than 12 days. Females from all-female populations produced by treatment with sex hormones were mated with normal males resulting in nine spawns with a sex ratio different from 1:1. The sex ratios were statistically similar to 3 male: 1 female in five spawns, both 2:1 and 3:1 in two spawns, and 2:1 in two spawns. These data are consistent with a model for female homogametic sex determination in channel catfish and suggest that the YY equivalent genotype is viable.

Plasma Corticosteroids and Chlorides in Striped Bass Exposed to Tricaine Methanesulfonate, Quinaldine, Etomidate, and Salt

Abstract Plasma chloride and corticosteroid concentrations were measured in yearling striped bass (Morone saxatilis) exposed to 25 mg/L tricaine methanesulfonate, 2.5 mg/L quinaldine, or 0.1 mg/L etomidate (an experimental drug), alone and in combination with 10 g/L salt (NaCl). Plasma chloride levels were unaffected in all treatments during a 15-min exposure and during a 10-min period of close confinement in a dipnet. Plasma corticosteroids increased in fish exposed to salt alone and in fish exposed to tricaine methanesulfonate or quinaldine, either alone or in combination with salt. Etomidate alone or combined with salt limited the increase in plasma corticosteroids during exposure and confinement. Etomidate appears to be a useful drug for suppressing physiological changes during the handling and transportation of striped bass.

Biotic and Abiotic Influences on Corticosteroid Hormone Rhythms in Channel Catfish

Abstract Plasma-corticosteroid concentrations in resting channel catfish Ictalurus punctatus held at 21 C varied only slightly during a 24-hour period; further, increases in hormone concentrations induced by confinement stress were independent of time of day and photoperiod. Temperature strongly affected both resting corticosteroid concentrations and the dynamics of hormone secretion when fish were stressed. Resting concentrations were greatest in fish acclimated to 5 and 10 C (25–29 ng/ml), sharply lower in fish held at 15, 20, or 21 C (5–9 ng/ml), and intermediate in fish maintained at 25, 30, or 35 C (12–13 ng/ml). Hormone concentrations increased when fish were stressed by confinement. Corticosteroid concentrations hardly changed in fish held at 5 or 10 C, but increased markedly in fish at higher temperatures; in addition the response was more delayed at the lower temperatures.

Influence of Nitrite and Chloride Concentrations on Survival and Hematological Profiles of Striped Bass

Abstract The 24-h median lethal concentration of nitrite (NO2 –) for striped bass Morone saxatilis was 163 mg/L in static toxicity tests. Exogenous chloride ions increased the tolerance of the fish for NO2 –; CaCl2 was more than twice as effective as NaCl. Plasma NO2 –, cortisol, and methemoglobin were correlated positively with environmental NO2 –. Plasma NO2 – and methemoglobin were correlated negatively with environmental Cl–, but cortisol was not reduced by the presence of environmental Cl–. Striped bass maintained NO2 – in the plasma (0–45 mg NO2 –/L) at concentrations below those in the environment (0–250 mg NO2 –/L). However, striped bass were sensitive to NO2 – that entered the plasma; methemoglobin levels greater than 60% and plasma NO2 –, levels greater than 70 mg/L resulted in significant mortalities.

Plasma corticosteroid and chloride dynamics in rainbow trout, Atlantic salmon, and lake trout during and after stress

Levels of plasma corticosteroids and chloride were studied in rainbow trout (Salmo gairdneri), lake trout (Salvelinus namaycush), and Atlantic salmon (Salmo salar) after 6 h of confinement in a shallow dipnet. Plasma corticosteroids increased more sharply in rainbow trout than in the other species during the confinement, and returned to resting levels more slowly. Plasma chloride levels decreased significantly from resting levels in both rainbow trout and Atlantic salmon confined for 6 h and had not recovered 12 h after release from the dipnet; very little effect was observed in lake trout. Both plasma corticosteroid and chloride dynamics appear to vary widely in closely related species. The differences do not appear to be related to ease of maintaining the species in captivity.

Tissue distribution and elimination of radiolabelled methyltestosterone fed to sexually undifferentiated blue tilapia

Abstract Populations of monosex male Oreochromis aureus can result when the synthetic androgen 17α-methyltestosterone (MT) is fed to sexually undifferentiated fish; however, concerns exist over residues of the androgen remaining in fish destined for human consumption. Radioactivity in the carcass and viscera was evaluated in juvenile fish fed steroid-incorporated diet (tritium and carbon-14 labelled MT and 30 μg unlabelled MT/g feed) for 21 days, and depletion was monitored for 21 days after return to an untreated diet. Radioactivity was detected in the carcass within 1 h after initial feeding and reached highest levels by 6 h. Most of the radioactivity (> 90%) was in the viscera during the 21 days the radio-labelled diet was being fed. Radioactivity was eliminated exponentially, decreasing by 90% within 24 h after the last feeding. After 21 days of feeding untreated diet,

Chronobiologic Approach to Aquaculture

Abstract Diel and seasonal changes in the environment directly or indirectly control many biological functions. Chronobiology, the study of biological functions in relation to time of day, time of year, lunar phases, and other consistent cues, could have important applications in aquaculture. Physiological conditions that vary seasonally include feeding time, tolerance of fish to stress, the state of gonad development, lipid and water content of muscle tissue, and the dress-out weight of food fish. The quality of cultured fish may vary with the time of day when fish are fed, seined, graded, treated with therapeutic chemicals, injected with hormones, or physically disturbed. Efficiency of production and quality of aquacultural products might be improved if the activities of fish husbandry were timed to coincide with the biological rhythms of fish.