Distance between Fishes in the Shoals and the Possibility of Estimating Their Biomass
Information about the structure fish schools allow to estimate biomass accumulation on the basis of the size of schools and the distance between the individuals. Information about the density of the flocks are expressed in terms of the distance between fish, from which the filling of valium and amount of fish biomass follows. This allows to calculate the proportion of the volume of the medium occupied by the fish as relation of one individual volume (usual 0,01L3) and the volume of water per one individual (nL)3 where n is the distance between individuals, ie 0,01/n3. Data about structure of swarms obtained by photographing under water from manned vehicles, submersible cameras and photo of divers. The structure of schools in their natural environment in epipelagic and the littoral zones of water bodies is studied by the photo from above - aerial vehicles, tethered balloons, natural and artificial elevations and rods. The study of the density of the swarms on stress was held in artificial containers. The article analyses the photos provided in literature and own materials underwater and surface shots. Distance between the fish in quit flocks has an average value about 2,44 (2,14-2, 59) body length (L). From this follows that the volume of water per fish is 14,5 L3, and when the volume of fish is 0,01L3, filling of volume is about 0,076%. Calculation shows, that the volume of fish in school differs from 0,016% at distance 4L to 8% at distance 0,5 L. Stress reduces the distance to 0,26-0,1L. In some special cases (together foraging, spawning migration, pre-spawning aggregation) distance may be different - plankton filtering mackerel - 0,24L, migrating salmon - 0,5L, feeding mullet - 0,025L, harengula in the shallows - 0,1-1L, mixed flocks of coral fish -1,5 L. At the surface and bottom feeding fish forms a single layer packs.