Catch Assessment Survey
Total catch : The relationship, which is used to estimate the total catch, is :
Total catch = ( catch per unit effort ) × ( total effort)
The amount of catch per unit of fishing effort is termed as Catch per Unit Effort ( CPUE).
Active fishing days : It is defined (gear specific) as the number of days in a reference period (e.g., a calendar month) during which fishing activities are normal. Usually this variable is defined in reverse manner, that is, by subtracting from the calendar days those days known for zero or negligible activity.
Effort: A fishing unit is defined by a fisher (or group of fishers in the case of gears such as the commercial seine nets) with a given types of gear and eventually the fishing craft used. One unit effort is defined by the fact that a given unit has fished during the past 24 hours. Two units mean that one fishing unit fished in two calendar days or two distinct units fished the same day. The definition does not account for differences in hours actually spent for fishing or in the time of the day, the fishing did occur. The estimated total effort is calculated separately for each group of fishing unit as follows :
Total effort = (N fishing unit) ×( days in the month) × CA
The total number of fishing units (N) is known from regular standardized counting of the number of fishermen and the number of gears used at different sanctuaries in a month. The proportion of fishing units that are expected to fish during any given days is called the Activity Coefficient. CA
Total catch is being calculated to identify the impact of fish pass. The species composition and number of species that has been caught in a specific year can also be known from this assessment. It gives a clear idea about fish diversity and availability of missing species in the Bangali River after implementation of the fishpass. In a word this assessment provides the impact of fishpass on fisheries resources of Bangali River after implementing the structure.