Appendix 6 – Escapes and native biodiversity

This Appendix details the method to calculate known escapes required by Indicators 2.4.8 and 2.4.10.

Known escapes are escape incidents where there is clear evidence that animals have escaped from captivity, whether or not the escape itself was directly observed. Evidence may include, for example, damaged or failed containment infrastructure, a sudden unexplained reduction in stock numbers linked to a specific incident, or reports of farmed fish being recovered outside the site. Known escapes can result from causes such as handling errors, containment failure, or other identifiable escape events.

On the contrary, unexplained losses are described as when the cause of loss is unknown. These losses can occur due to counting errors, undetected escapes, unrecovered mortalities or predation and cannibalism.

6.2 – Known escapes calculation (Indicators 2.4.8 and 2.4.10)

Known escapes shall be calculated as follows for all-in-all-out production methods:

$\text{Known escapes}(\%)=100*\frac{\text{Number of known escapes}}{\text{Number of stocked animals}}$

For cod and marine salmonid species, known escapes are counted individuals (not percentages).

$\text{Known escapes}(\%)=\frac{\text{known escapes}(\#\mathrm{animals})}{{\text{standing stock}}_{\text{start of yr}}(\#\mathrm{animals})+{\text{stocking count}}_{\text{during the yr}}(\#\mathrm{animals})}*100$