Document type: scientific protocol published in Center for Aquaculture Progress (2026)
Author: Center for Aquaculture Progress
Abstract in French (translation):
Protocol for Operational Welfare Indicators (OWI) in Rainbow Trout: Marine Aquaculture (Version 1.0)
To understand, monitor, and compare fish welfare in commercial aquaculture production systems, the industry needs Operational Welfare Indicators (OWI) protocols that draw on the full range of available scientific literature, ensure transparency in the development of their indicators, and provide practical guidance on how to assess fish welfare.
This protocol is the first tool of its kind designed to assess the welfare of farmed rainbow trout (Oncorhynchus mykiss) in seawater systems; it includes, in particular, a scoring system based on a comprehensive analysis of the scientific literature specific to the species and life stage for each indicator.
This protocol is intended for farm staff responsible for regular welfare monitoring, as well as other industry professionals, including certification bodies, auditors, and buyers. It is designed to align with the welfare monitoring and assessment requirements of major certifications, such as RSPCA Assured and the Aquaculture Stewardship Council. This protocol enables farm staff to systematically monitor the welfare of their stocks, quickly identify potential problems, and implement corrective measures.
This proactive approach helps producers understand the relationship between welfare and production performance, resulting in reduced losses, improved regulatory compliance, enhanced consumer confidence, and a stronger, more sustainable aquaculture industry.
Scope
Developed specifically for the farming of rainbow trout in seawater, this protocol may be applied to juveniles or other production systems provided it is interpreted rigorously. Although practical recommendations on welfare indicators (OWIs) have been developed for other species—such as the Laksvel protocol for Atlantic salmon—and valuable documents on rainbow trout welfare have been published by Nofima and APROMAR, existing resources do not provide a comprehensive, standardized, threshold-based assessment covering a wide range of indicators for rainbow trout producers. This protocol fills that gap. This protocol includes:
– 33 fish welfare indicators (OWI) divided into three categories:
+ 14 individual indicators
+ 5 group indicators
+ 14 environmental indicators
– A scoring system for each indicator, divided into four levels ranging from 0 to 3
– Reference images and scoring guidelines for practical application in the field
Preview:
To understand, track, and compare fish welfare in commercial aquaculture production systems, the industry requires Operational Welfare Indicator (OWI) protocols that build on the full available scientific literature, provide transparency into the development of their indicators, and feature practical guidance on how to score fish welfare.
This protocol is the first such tool for assessing the welfare of farmed rainbow trout (Oncorhynchus mykiss) in seawater systems, including a scoring system based on a comprehensive species- and life-stage-specific literature review for every indicator.
This protocol serves farm personnel conducting routine welfare monitoring and other industry professionals, including certification bodies, auditors, and buyers. It is designed to align with the welfare monitoring and assessment requirements of key certifications, such as RSPCA Assured and Aquaculture Stewardship Council. This protocol enables farm personnel to systematically monitor the welfare of their stock, identify potential issues early, and implement corrective actions.
This roactive approach helps producers understand the relationship between welfare and production performance, resulting in reduced losses, improved regulatory compliance, strengthened consumer trust, and a stronger and more sustainable aquaculture industry.
Scope
Developed specifically for ongrowing rainbow trout in seawater, this protocol may be applied to juveniles or other production systems with careful interpretation. While practical guidance on OWIs has been developed for other species, such as the Laksvel protocol for Atlantic salmon, and valuable documentation on rainbow trout welfare has been published by Nofima and APROMAR, existing resources lack comprehensive, standardized, and threshold-based assessment across a wide range of indicators for rainbow trout producers. This protocol addresses that gap.This protocol includes:
– 33 OWIs across three categories:
+ 14 individual-based indicators
+ 5 group-based indicators
+ 14 environmental indicators
– Scoring system for each indicator, split into four tiers comprising levels 0–3
– Reference images and scoring guidance for practical field application
