Water Quality Monitoring Procedure

Purpose. Describes how dissolved oxygen, temperature, salinity and other water quality parameters are measured, recorded and acted on at the sea farm and in the hatchery.

1.Equipment

Farm crews must use the handheld multiparameter meter allocated to their boat and check its calibration against the reference solution each morning before use. The hatchery uses fixed probes on each system with a handheld cross check each shift. A meter that fails calibration must be tagged out and recorded in the Vessel and Equipment Register.

2.Sea farm readings

Dissolved oxygen, temperature and salinity must be measured at every cage at the morning feed and again in the afternoon, at one metre and at five metres depth. Readings must be entered in the Farm Stock and Water Quality Log at the time of measurement with the cage number, depth and time. Readings must never be estimated or entered later from memory.

3.Action levels

Dissolved oxygen below six milligrams per litre at any cage requires feeding to stop at that cage and the leading hand to be told. Below five milligrams per litre the Sea Farm Manager must be told immediately, feeding stopped across the site, and the low oxygen response in the Aquaculture Emergency Procedures Plan started. Temperature above the upper limit in the health plan requires reduced feeding and increased observation.

• Below 6 mg/L: stop feeding that cage, tell the leading hand
• Below 5 mg/L: stop all feeding, tell the manager, start the emergency plan
• Temperature above the health plan limit: reduce feed, observe stock hourly

4.Hatchery readings

Each recirculating system must have dissolved oxygen, temperature, pH, ammonia, nitrite and nitrate recorded each shift. Alarms must be tested weekly. Any parameter outside its limit must be recorded with the corrective action taken and reported to the Hatchery Manager before the end of the shift.

5.Trends and reporting

The leading hand must review the log each afternoon for trends across cages and report any cage that is consistently lower than its neighbours. Weekly summaries must be sent to the Sea Farm Manager and the veterinarian.