ssb {FLCore} | R Documentation

## Method ssb

### Description

Returns the Spawning Stock Biomass of `FLStock` and `FLBiol` objects.

For `FLStock-class` objects the nature of the calculation depends on the units in the harvest slot. See details below.

### Generic function

ssb(object)

### Methods

signature(object=FLStock) :
  If spawning occurs at the beginning of the year the calculated SSB is the same regardless of the units of the harvest slot. If spawning occurs at any other time during the year such that the stock is subject to fishing mortality prior to spawning then the calculated SSB will depend on the units of the harvest slot.

  For an `FLStock-class` with harvest units 'f' SSB is calculated as

  SSB = sum(N*exp(-F*propF-M*propM) * wt * mat)

  For an `FLStock-class` with harvest units 'hr' SSB is calculated as

  SSB = sum(N*(1-harvest)*exp(-M*propM) * wt * mat)

  The units of the harvest slot in the `FLStock` object must be specified as either 'f' for an instantaneous fishing mortality or else as 'hr' for a harvest rate.

signature(object=FLBiol) :
  For an `FLBiol-class` the spawning biomass at the beginning of the year is calculated.

  SSB = sum(N * wt * mat)

### Author(s)

The FLR Team

### See Also

FLBiol-class FLStock-class

### Examples

     data(ple4)
     units(harvest(ple4)) # check the units of the harvest slot
     ssb(ple4)

[Package FLCore version 2.2 Index]