IMPACT OF TEMPERATURE AND RAINFALL ALTERATIONS ON SPAWNING BEHAVIOUR OF INDIAN MAJOR CARPS AND CONSEQUENCE ON FISHERS’ INCOME IN ODISHA M. K. DAS, P. K. SRIVASTAVA, S. DEY AND A. REJ Central Inland Fisheries Research Institute, Barrackpore – 700 120 (Received : 12.08.2012; Accepted : 01.12.2012) The present communication assessed the impact of the changes in climatic variables, viz. temperature and rainfall on the spawning of Indian Major Carps (IMC) in the river Mahanadi, in the fish hatcheries in its plains and on the fishers’ income in five districts of Odisha. The average minimum and maximum temperature throughout the state has increased in the range of 0.1 °C to 0.9 ºC. The annual rainfall in Cuttack and Puri districts have increased by 27.78 mm and 13.20 mm respectively and decreased by 18.73 mm, 16.25 mm, 7.4 mm, 86.88 mm and 11.25 mm in Angul, Balasore, Khurda, Sambalpur and Bolangir districts, respectively during 1981-2010. The fish spawn availability has decreased drastically in river Mahanadi in three decades from 30-43 ml net -1 day -1 to the present level of 6 ml net -1 day -1 . The study revealed that the onset of the breeding period of the Indian major carps has advanced by one month in the hatcheries, compared to the previous two decades. The advancement in breeding period of IMC in the fish seed hatcheries in Balasore, Khordha, Puri and Mayurbhanj districts can be attributed primarily to the effect of increased water temperature and shifting of the rainfall pattern facilitating early maturation and spawning. The respondents in the fish seed hatcheries surveyed also perceived temperature and rainfall as the most important factors responsible for advancement of the onset of breeding of IMC. Key words : Climate change, breeding season, Indian major carps, hatchery, Mahanadi river basin, Odisha, India J. Inland Fish. Soc. India, 44 (2) : 1-11, 2012 Introduction In recent years the climate is showing perceptible changes on a regional scale in India. In the state of Odisha the average temperature is on the rise over the last 30 years. The average minimum and maximum temperature throughout the state has increased in the range of 0.1 °C to 0.9 ºC (IMD, 2010). The average rainfall has decreased with a shift in the seasonal pattern. With this background, investigation was conducted to assess the impact of the alteration in the climatic variables on the breeding of Indian major carps in the river Mahanadi and Brahmani and in the fish hatcheries in its plains and on the fishers in five districts of Odisha. Materials and methods Study area Study was undertaken in five districts of Odissa in the Mahanadi river basin, viz. Puri, Khorda, Balasore, Cuttack and Angul. (Fig. 1) Meteorological data analysis Rainfall The rainfall pattern of the districts in the Mahanadi basin of Odisha were analysed from data available with Indian Meteorological Department (IMD), Pune. The Annual rainfall data were clubbed into three blocks of pre 90’s (1981-90), 90’s (1991-2000) and post 90’s (2001-2010) since most of the fish seed hatcheries came up during 1