Emerging indicators of fish welfare in aquaculture

Abstract

As aquaculture continues to grow and intensify, there is an increasing public concern over the welfare of farmed fish. Stress and production‐related pathologies and repressed growth are examples of the challenges facing aquaculture, and their impacts could be minimised by effective identification of the early signs of impaired welfare. Many welfare monitoring methods have been recommended; however, continuous and reliable welfare monitoring in aquaculture is not yet widespread and commonplace. The aim of this scoping review was to present an overview of the most recent developments in fish welfare assessments with a specific focus on practical translation to the aquaculture industry. A keyword‐based search was undertaken to identify peer‐reviewed papers published between 2014 and 2020 in which a novel method with the potential to be used for the assessment of fish welfare in aquaculture was introduced. The results were sorted into two categories: non‐invasive and invasive methods. All methods were assessed for their advantages and disadvantages, potential applicability to aquaculture. Invasive methods were also ranked on their degree of impact. It is concluded that increased interest into fish welfare, in combination with more intelligent modern technology, has resulted in the development of newer and more refined alternatives to traditional methods of welfare assessment such as behaviour monitoring by 2D cameras and plasma cortisol evaluation. Although, in many cases, more research is needed before these methods are suitable for widespread industry use, studies that focus on increasing the precision, automation and practical applicability of these methods are a promising avenue for future research.

Revising the Impact and Prospects of Activity and Ventilation Rate Bio-Loggers for Tracking Welfare and Fish-Environment Interactions in Salmonids and Mediterranean Farmed Fish

“…The potential benefits are obvious because fish with high stress resilience are less susceptible to diseases, show better growth performance, and provide a better-quality product (Ashley, 2007). However, animal health and welfare issues are of increasing public concern, and livestock industries and aquaculture in particular require to project a welfarefriendly image of their products (Hemsworth and Coleman, 2011;Toni et al, 2019;Barreto et al, 2021). The challenge is that fish aquaculture involves a huge number of species and the understanding of their welfare biology is limited, which explains why relatively few operational welfare indicators (OWI) are used to assess welfare status on commercial aquaculture facilities (Segner et al, 2019).…”

Effects of Stocking Density on the Growth Performance, Physiological Parameters, Redox Status and Lipid Metabolism of Micropterus salmoides in Integrated Rice–Fish Farming Systems

“…Welfare is an increasing public concern in farmed fish. Accumulating evidence suggests that fish experience poor welfare under adverse conditions, accompanied by altered growth performance, physiological parameters and behavior [ 98 ]. The stress response is a common event when fish are subjected to poor welfare, and thus, physiological indicators of stress, including cortisol, glucose and lactate, are frequently used to evaluate the welfare of farmed fish [ 99 ].…”

Assessing Stress Resilience After Smolt Transportation by Waterborne Cortisol and Feeding Behavior in a Commercial Atlantic Salmon (Salmo salar) Grow-Out Recirculating Aquaculture System

“…Accordingly, water quality sampling protocols and sensor technologies have been developed to ensure cost-effective production (Su et al, 2020), supported by maintaining good rearing conditions in terms of water quality and fish health and welfare. In addition to water quality-based health and welfare indicators, techniques for monitoring the physiological state of the fish provide important information needed to safeguard the health and welfare of farmed fish (Baretto et al, 2022). Currently, fish-based non-invasive welfare indicators are often based on behavioral and respiratory changes, and the use of other measures is limited (Baretto et al, 2022).…”

“…In addition to water quality-based health and welfare indicators, techniques for monitoring the physiological state of the fish provide important information needed to safeguard the health and welfare of farmed fish (Baretto et al, 2022). Currently, fish-based non-invasive welfare indicators are often based on behavioral and respiratory changes, and the use of other measures is limited (Baretto et al, 2022).…”