New Protocol Establishes 33 Indicators for Rainbow Trout Welfare in Seawater
- The Centre for Aquaculture Progress has released a new evaluation protocol establishing 33 operational welfare indicators, known internationally as OWI, to assess the well-being of rainbow trout during...
- The protocol distributes its 33 indicators across three specific categories.
- Temperature parameters receive strict numerical thresholds under the new guidelines.
The Centre for Aquaculture Progress has released a new evaluation protocol establishing 33 operational welfare indicators, known internationally as OWI, to assess the well-being of rainbow trout during the seawater grow-out phase, according to coverage by Mundoacuicola. The digital interactive and downloadable tool aims to help producers, professionals, auditors, and certifiers evaluate fish health and production system conditions without depending exclusively on laboratory tests.
Three Dimensions of Fish Welfare and Evaluation Structure
The protocol distributes its 33 indicators across three specific categories. Fourteen metrics cover individual evaluations, five focus on group behavior or performance, and another fourteen examine environmental conditions. The individual assessment allows operators to grade spinal deformities, body condition, scale loss, skin hemorrhages, wounds, color changes, and damage to the snout, jaw, eyes, opercula, gills, and fins, along with the presence of sea lice. Group indicators track mortality rates as well as abnormal, aggressive, feeding, and swimming behaviors, which help farm managers detect health or environmental issues before severe lesions develop. The environmental dimension monitors stocking density, dissolved oxygen, temperature, carbon dioxide, pH, turbidity, suspended solids, ammonia, nitrite, nitrate, metals, water speed, salinity, and hydrogen sulfide. Each indicator utilizes a four-level scale ranging from zero to three, where lower scores represent favorable conditions and higher levels indicate progressive deterioration requiring corrective action. The document provides reference images, measurement instructions, and scientific background to ensure consistency in the field.
Temperature Thresholds and Mortality Monitoring Standards
Temperature parameters receive strict numerical thresholds under the new guidelines. The protocol assigns level zero to temperature intervals above 13 degrees Celsius and up to 16 degrees Celsius. Temperatures above 10 and up to 13 degrees Celsius, or above 16 and up to 18 degrees Celsius, receive level one. Level two covers temperatures above four and up to 10 degrees Celsius, or higher than 18 and up to 20 degrees Celsius. Registries equal to or below four degrees Celsius, or exceeding 20 degrees Celsius, reach level three. The protocol recommends continuous temperature measurement and manual equipment verification at least twice daily, ideally at sunrise and sunset. Operators should record data at multiple depths because trout can move within the water column to find favorable conditions. For mortality tracking, level zero corresponds to daily losses equal to or below 0.014 percent or an annual rate of 5 percent. Daily mortality exceeding 0.061 percent or an annual rate of 20 percent falls into level three. The guidelines advise recording both the count and the underlying causes of losses to spot trends and prevent future events.
