The Effects of High Temperatures on Roach (Rutilus Rutilus)

Abstract

1. The temperature at which 50% of a sample of roach (Rutilus rutilus) die within a week cannot be raised above 33.5° C. by raising the acclimatization temperature. 2. The roach is about as eurythermal as the yellow perch (Perca flavescens). 3. The mean asphyxial concentration of oxygen at 30 and 32°C is approximately 0.8 mg./l. 4. Median survival time at any lethal temperature increases with increase in acclimatization temperature; survival time for any acclimatization temperature decreases as test temperature increases; the temperature at which 50% of a sample die within a week rises by about 1° C. for each 3° C. rise in acclimatization temperature. 5. The behaviour, on transfer to higher temperatures, depends on the acclimatization temperature and the size of the jump in temperature and can be divided into five characteristic stages. 6. Dying fish develop a black pattern; myotomic swimming muscles die first and opercular muscles last. The heart was still beating when the fish were opened but the gall bladder was abnormal.