Ecological fish production in the inland delta of the Middle Danube, a floodplain river

Ecological fish production in one parapotamal arm of the Middle Danube inland delta in Slovakia, based on 10 samplings during 5 consecutive years, ranged from 349 to 3272 ((x) over bar = 1066) kg ha(-1) in total production (P-T) and from 39 to 662 ((x) over bar = 204) kg ha(-1) in available production (P-A). Young-of-the-year fish made up an estimated 49-62% ((x) over bar = 54) of the P-T. According to the food production/food consumption budget calculated by three different methods, less than half of the P-T is of autochthonous origin, while most is from other sources. Floodplain fish production includes two components: fish originating within the floodplain and fish that are temporary immigrants. The latter component varies considerably in response to the hydrological regime. To assess the P-T in riverine ecosystems, different seasons and years are needed to give realistic values.