A Study on Fish Reproduction with Reference to Temperature Anomalies in Kosi Region of Bihar

Changes in temperature and climatic condition affect aquatic life. Temperature is a fundamental physical regulatory factor in the lives of fishes and its effect expressed particularly strongly in the control of all reproductive processes. In the present study an attempt has been made to analyse the main objective like the effect of temperature anomalies. This study has revealed that water temperature has inverse effect on reproduction process of fishes. Water temperature above optimum range will slow the reproduction process. There is an optimal temperature range for breeding of fishes. Critical temperature limits exist, above and below which fish will not reproduce. Warm temperature plays a primary role in stimulating the maturation of gonads in many fishes. Temperature has a direct effect on gonads, regulating their ability to respond to pituitary stimulation and effects on primary synthesis and release of gonadotropins. Carps labeo rohita have thermal tolerances in the 2232 C range. Most of fish species show gonadal activity during July- Sep (Temp. range 20 C - 32 C) in the study area of koshi region of bihar depending on their geographical location. Since the Indian major carps show gonadal activity from March to June, at a time when both photoperiod and temperature are increasing, it is summarised that these two factors are involved in initiating gonadal recrudescence. Warm temperatures and long photoperiod coupled with good diet are responsible for accelerated growth and gonadal maturity. In the present study, The scholar has recorded the average temperature range in different months of year 2011 and correlated it with the stage of oocyte of fishes collected from its natural habitat of kosi region. The oocytes of collected specimen were observed and are counted based on the stage of maturity. The observation showed that the study area of kosi region of Bihar where winter and summer seasons are so clearly defined, the only time when temperature conditions remain fairly uniform is that of the monsoons. All fishes, therefore, breed preferably during this season under optimum temperature ranging between 20 C to 32 C. In this period, Due to prevailing flood conditions in koshi region, there is no competition for space. Each species, therefore, gets the best chance of finding suitable grounds to settle. Elevated temperatures increase the metabolism, respiration and oxygen demand of fish and other aquatic life, approximately doubling the respiration for a 10C rise in temperature. Hence the demand for oxygen is increased under conditions where oxygen supply is lowered.