About biomass estimation

Echoview can apportion integrated backscatter data to individual species and estimate the density of those species within a domain of analysis. This feature is available when exporting analyses from echograms or scenes.

Preparation

Before biomass can be estimated you must define regions, region classes and species to suit your needs. Echoview provides a default region class and a default species with default properties, but it is important that you adjust these to suit your environment.

Species are defined and allocated to region classes on the Classes page of the EV File Properties dialog box.

Region classes are assigned to regions using either:

Notes:

Estimating Biomass from single beam data

For single beam data the biomass estimates are exported from echograms.

Two analysis variables for estimating biomass are available for export. Each species within each region (and optionally within each cell) has:

Density_number = The number of individual specimens of this species per unit of water surface area (see units below)

Density_weight   = The total weight (mass) of this species per unit of water surface area (see units below)

These are exported only if selected on the Export page of the EV File Properties dialog box and only when exporting integration analyses of regions (Integration by Regions or Integration by Regions by Cells).

Notes:

Estimating Biomass from Multibeam data

For multibeam data the biomass estimates are available from scenes.

Four analysis variables for estimating biomass are available for export. Each species within each region has:

Density_number = The number of individual specimens of one species per unit of water volume (see units below)

Density_weight   = The total weight (mass) of one species per unit of water volume (see units below)

Fish_number       = The number of individual fish of one species in the volume of water contained within a region.

Fish_weight         = The total weight of fish of one species in the volume of water contained within a region.

The species to which these four variables apply is identified by the species_name exported along with these variables.

Units

When analyzing single beam data, Echoview makes these analysis variables available per square nautical mile or per hectare. The preferred unit can be set using the Biomass export box on the Export page of the EV File Properties dialog box.

When analyzing multibeam data these analysis variables are available per cubic meter only.

See also

About analysis variables
About species

About region class

About regions
Density_number

Density_weight

Fish_number

Fish_weight

N_sigma_bs

About samples and echo-integration
About analysis domains