New indices for the diagnosis of fish welfare and their application to the grass carp ( Ctenopharyngodon idella ) reared in earthen ponds

Abstract

Animal welfare is an issue of increasing importance in global aquaculture. However, the incorporation of this issue into routine aquaculture operations is a challenge. A possible path to change this is the recognition, identification and addressing of the ecological, physiological, nutritional, behavioural and psychological needs of fish. The present study uses grass carp (Ctenopharyngodon idella), the world's most widely produced fish species, and earth ponds, the world's most widely used production system in fish farming worldwide, as the basis for developing indices to assess and monitor the welfare of farmed fish. The proposed indices were structured based on specific welfare indicators, reference values, individual weights and associated scores to address the Animal Welfare Five Freedoms and a Life Worth living concepts. Two types of indices were proposed: (1) partial welfare indices (PWIx), specific to each of the four observed/analysed freedoms; (2) general welfare index (GWI), which simultaneously summarizes the addressees' freedoms in a single variable. Both indices range from 0 (critical welfare impairment) to 1.0 (minimal risk of welfare impairment). The study was based on a comprehensive systematic review of the literature using the PRISMA method. The proposed indices were based on 10 environmental indicators, nine indicators for health, five for nutrition and four for behaviour. The PWIx can be used to determine how each category of indicators contributes to the GWI, which defines the level of fish farm welfare at a given point in time and which needs are affected or met during a production cycle.

Constraints Affecting the Welfare of Domestic Sheep Grazing in the Natural Pasture

“…These days, the majority of welfare studies start off by outlining the animal's requirements, including those for specific behaviors [50]. This method superseded earlier generic rules imposed by freedoms using cutting-edge research on what was significant to animals [51]. There are now several well-being indicators that show how welfare is doing.…”

From egg to slaughter: monitoring the welfare of Nile tilapia, Oreochromis niloticus, throughout their entire life cycle in aquaculture

“…The current paradigm regarding the welfare of farmed fish suggests that the evaluation parameters used should be specific to each species, considering the animals' developmental stage and the system in which they are raised. These parameters should also encompass indicators that address the fish's physical, nutritional, environmental, and behavioral aspects ( 13 , 23 , 25 , 26 , 87 , 119 , 122 ). However, the understanding and investigation of the psychological dimensions, although constituting one of the animal freedoms, represent a field of scientific knowledge still in its early and nascent stages, especially when compared to the progress achieved regarding animals involved in terrestrial agriculture.…”

“…When we originally proposed the method and indices that our group has already applied to assess the degree of welfare in grass carp and white-leg shrimp ( 25 , 26 ), we emphasized that the indicators, their reference values, scores, and weights would need to be periodically reviewed and updated as scientific knowledge advances on the subject. In this article, we put this concept into practice by applying our metrics to assess the welfare of tilapia not only during the grow-out phase but throughout all life stages, whilst also revising and advancing the knowledge generated previously.…”

“…The fifth freedom, psychological, is intrinsically evaluated through the behavioral and physical analysis of the animals. The methodology employed followed the same principles already used in the creation of the protocols previously developed by our group for O. niloticus ( 23 ) and grass carp, Ctenopharyngodon idella ( 25 ), during the grow-out phase of both and also for white-leg shrimp, Penaeus vannamei throughout its entire production cycle ( 26 ).…”

“…Calculation of tilapia welfare indices utilized the same mathematical equations proposed by Pedrazzani et al ( 25 ) for evaluating the welfare degree of C. idella . The weights assigned to each indicator in the respective indices were established based on the number of valid bibliographic references found for O. niloticus in each production phase, using Google Scholar as the research platform.…”