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Geology topics

N. C. Parker

Publications and source records attributed to N. C. Parker.

27 records · Page 2Linked to original sources

Chronobiologic approach to aquaculture

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.

Transactions of the American Fisheries Society

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.

Aquaculture

Plasma corticosteroids and chlorides in striped bass exposed to tricaine methanesulfonate, quinaldine, etomidate, and salt

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.

Progressive Fish-Culturist