WWW.WAS.ORG • WORLD AQUACULTURE • MARCH 2023 41 (CONTINUED ON PAGE 42) experience feelings, ranging from negative to positive. The domains of the current model are: 1) Nutrition, 2) Physical Environment, 3) Health, 4) Behavioral Interactions and 5) Mental State. The first four domains (Nutrition, Environment, Health and Behavior) help inform about the animal’s various experiences, which make up the fifth domain, the Mental Domain. It is in this context that researchers, technicians, farmers and industry stakeholders have developed and deployed a framework combining the most current species-specific scientific knowledge, a practical assessment protocol and an easy and free-to-use farm application that allows fish assessments during farming routines, with quick user feedback and progress monitoring. In this article, we focus on tilapia welfare assessment in the grow-out stage but this framework can be applied to any species of interest at any stage of production. The Welfare Assessment Protocol Applied to Tilapia Grow-out To assess the welfare of tilapia, there are 28 welfare indicators that are categorized based on the four objective welfare domains (Fig. 1). For each area, a three-level scoring system was defined (Table 1). The higher the score, the greater the deviation from the normal condition. Health Indicators (9). If the animal is injured or sick, with mobility difficulties, growth abnormalities, lethargy, without appetite, and with rotten or closed fins, it has a poor health status and is most probably under stress and suffering. Every time fish are exposed to a stressor, such as low water temperature or air and light exposure during capture, the animal initiates a response in an attempt to restore balance with the environment, and readjust its biological activities. The physiological stress response can be divided into primary, secondary and tertiary responses. In the primary response, the brain is activated and directs the rapid release of stress hormones into circulation. In the secondary response, there is an immediate reaction of the blood and tissues to these hormones, such as an increase in heart rate, blood sugar and oxygen levels in the blood. The tertiary response occurs when the stressor persists for a long time. The fish gets exhausted, and growth and reproduction are compromised. The immune responses are weakened, facilitating the onset of diseases. Nutrition Indicators (6). For fish to grow healthy, they need nutritious food. However, an appropriate type of feed for the fish grow-out stage and production systems is not enough. Fish need to eat in sufficient quantities — usually described as a percentage of fish body weight — several times per day, depending on the life stage, and at specific times of the day, avoiding nighttime and assuring that oxygen is sufficient. The farmer needs to establish efficient feeding routines to prevent stress, aggression, cannibalism and lesions in the eyes and fins. Environment Indicators (10). Environment indicators include the water physicochemical characteristics, photoperiod, the presence of terrestrial predators and non-specific inhabitants, including fish of other species that live in the same water body. Behavioral indicators (3). Behavioral indicators are based on the display of abnormal behaviors and restrictions on the species’ natural behavioral portfolio. In specific management routines, such as feeding, harvest and slaughter, it is possible to observe the animals’ behavior. The response to these events can indicate their degree of well-being. If fish become exhausted during harvest and take too long to lose consciousness during slaughter, the fish will suffer. This extremely stressful and painful event will decrease the flesh quality and product shelf life. The farmer may need to improve the harvesting and slaughter process to make it quicker and less stressful. Making Monitoring Easy To make the welfare monitoring easier, standardized and allow for corrective actions, FAI created the tilapia welfare application. The app records the data, automatically makes the necessary calculations and suggests corrective actions. The assessment tool can be used by farmers or processors. Users are guided through a series of simple questions that will help them to monitor and drive progress regarding welfare and best practices. Answering the relevant questions generates immediate feedback, either directly or through e-learning activities, allowing tilapia producers to continuously improve their production practices. Harvest and slaughter: critical events in fish welfare Scoring effective stunning is critical for securing the welfare of the animal. To score this parameter the best way is to measure the time it takes for fish to lose consciousness during stunning. Consciousness is verified by four clinical reflexes: Opercular beat (OR): OR is the simplest way to estimate respiratory rate, by counting the opercular movement, which is directly proportional to the level of consciousness. Vestibulo-ocular reflex (VOR): VOR is measured by the visual evoked response (VER) or “rolling of the eyes,” which is the movement of the eyes when the fish’s body is rolled from side to side on the vertical axis. Equilibrium (EQ): EQ is assessed by the position of the fish and its ability to swim when placed in the water. Tail grip reflex (TGR): TGR is the technique of grabbing the animal’s tail to check if the fish tries to escape, being an effective way to assess the fish’s ability to interact with the external environment. TABLE 1. The three-score system. Score Description 1 – Good The normal reference for a specific parameter. 2 – Moderate Values normally tolerated by tilapia but not ideal. 3 – Poor Values that significantly affect the welfare of tilapia, whcih can lead to severe suffering and even death of the animals.
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