A Brief Look into the Origins of Fish Welfare Science

Chronic stress negatively impacts wound healing, welfare, and stress regulation in internally tagged Atlantic salmon (Salmo salar)

The desire to understand fish welfare better has led to the development of live monitoring sensor tags embedded within individuals for long periods. Improving and understanding welfare must not come at the cost of impaired welfare due to a tag’s presence and implantation process. When welfare is compromised, the individual will experience negative emotions such as fear, pain, and distress, impacting the stress response. In this study, Atlantic salmon (Salmo salar) underwent surgical implantation of a dummy tag. Additionally, half of this group was introduced to daily crowding stress. Both groups and an untagged group were followed for 8 weeks using triplicate tanks per group. Sampling took place once a week, and where stress was given, it was conducted 24 h before sampling. Stress-related measurements were taken to understand if tagging caused chronic stress and explore the chronic stress response and its impact on wound healing. Primary stress response hormones measured included CRH, dopamine, adrenocorticotropic hormone, and cortisol. Secondary stress response parameters measured included glucose, lactate, magnesium, calcium, chloride, and osmolality. Tertiary stress response parameters measured included weight, length, and five fins for fin erosion. Wound healing was calculated by taking the incision length and width, the inflammation length and width, and the inside wound length and width. The wound healing process showed that stressed fish have a larger and longer-lasting inflammation period and a slower wound healing process, as seen from the inside wound. The tagging of Atlantic salmon did not cause chronic stress. In contrast, daily stress led to an allostatic overload type two response. ACTH was elevated in the plasma after 4 weeks, and cortisol followed elevation after 6 weeks, highlighting a breakdown of the stress regulation. Fin erosion was elevated alongside cortisol increase in the stressed group. This data suggests that tagging previously unstressed fish in a controlled environment does not negatively affect welfare regarding stress responses. It also indicates that stress delays wound healing and increases the inflammatory response, highlighting how continued stress causes a breakdown in some stress responses. Ultimately, the tagging of Atlantic salmon can be successful under certain conditions where proper healing is observed, tag retention is high, and chronic stress is not present, which could allow for the possible measurement of welfare indicators via smart-tags.

Psychological and social well-being of bony fishes in zoos and aquariums

Research on the behavior of animals in zoos has been conducted for decades and observations have provided information that has improved the psychological and social well-being of animals. However, research on fishes in zoos and aquariums seems to be lacking. Here we assess the current state of research on fishes in zoos and aquariums by surveying peer-reviewed literature. Our assessment differs from previous surveys in that we examine the taxonomic classes Chondrichthyes (sharks and rays) and Osteichthyes (bony fishes) separately. Our survey finds that bony fishes have been drastically underrepresented in zoo journals, more so than chondrichthyans, revealing an urgent need for zoos and aquariums to conduct research on the behavior of the bony fishes in their care, to ensure a positive state of psychological and social well-being. To plot a course for the future, we discuss the few studies that have been conducted on the behavior of bony fishes in zoos and aquariums, and we discuss research conducted on bony fishes in food-fish aquaculture and biomedicine to identify the types of studies that could be conducted in zoos and aquariums. We conclude that data-driven analyses of fish behavior could aid in development of evidence-based practices that enhance the well-being of bony fishes in zoos and aquariums, just as they already do for terrestrial animals.

Estimating Discard Mortality in Commercial Fisheries without Fish Dying: A 3R Challenge

Simple Summary

Due to the implementation of a landing obligation in fisheries in the European Union (EU), with an exemption for species with “high survival”, discard survival studies (henceforth DSSs) have become one of the most politically prioritized fisheries research areas in European fisheries. In contrast to most fisheries science research areas, DSSs are embedded by the EUs animal research welfare directive. This is a challenge, and there has not been any focus on how to implement animal welfare (AW) regulations experimentally in DSSs. This paper focuses on AW regulations in relation to conducting DSSs, but the outreach is much broader. We investigate experimental procedures by bringing in relevant examples, using the output results, and relating this information to relevant AW guidelines and regulations by focusing on implementing 3R principles.

Abstract

Globally, it is estimated that around 10% of the fish that are caught are discarded. This is considered to be a wasteful human marine activity since these fish are often dead or dying. To reduce the high discard rates of commercial fisheries, the European Union (E.U.) has enacted a landing obligation that includes the ability to exempt “species for which scientific evidence demonstrates high survival rates”. Therefore, discard survival studies (henceforth DSSs) have become one of the most politically prioritized fisheries research areas in European fisheries. International expert groups have produced guidance reports to promote best practices and to harmonize the methodologies. Nevertheless, there has not been any focus on how to implement animal welfare (AW) regulations experimentally. Discard survival studies are “frontrunners” in fisheries science research areas that are embedded by animal research welfare requirements and are expected to be more restrictive in the future because of an increased public focus on fish welfare. This paper focuses on AW regulations in relation to conducting DSSs, but the outreach is much broader. We investigate experimental procedures by bringing in relevant examples, using output results, and relating this information to relevant AW guidelines and regulations by focusing on implementing 3R principles.

Minding the Gaps in Fish Welfare: The Untapped Potential of Fish Farm Workers

The welfare of farmed fish is often regarded with less concern than the welfare of other husbandry animals, as fish are not universally classified as sentient beings. In Norway, farmed fish and other husbandry animals are legally protected under the same laws. Additionally, the legislature has defined a number of aquaculture-specific amendments, including mandatory welfare courses for fish farmers who have a key role in securing animal welfare, also with regards to noting welfare challenges in the production process. This article uses fish welfare courses as a site from which to inquire about the common-sense understanding of fish welfare in Norwegian fish farming. The focus is specifically on fish farm employees, their experiences of welfare-related issues and contradictions in their daily work, and the struggle to act responsibly in aquaculture settings. Through participant observation at welfare courses, as well as interviews and conversations with fish farm workers, the article details how challenges are experienced 'on the ground', and suggests how fish farm workers' own experiential knowledge might be mobilized to improve the general welfare of farmed fish.

Animal welfare risks of global aquaculture

The unprecedented growth of aquaculture involves well-documented environmental and public-health costs, but less is understood about global animal welfare risks. Integrating data from multiple sources, we estimated the taxonomic diversity of farmed aquatic animals, the number of individuals killed annually, and the species-specific welfare knowledge (absence of which indicates extreme risk). In 2018, FAO reported 82.12 million metric tons of farmed aquatic animals from six phyla and at least 408 species-20 times the number of species of farmed terrestrial animals. The farmed aquatic animal tonnage represents 250 to 408 billion individuals, of which 59 to 129 billion are vertebrates (e.g., carps, salmonids). Specialized welfare information was available for 84 species, only 30% of individuals; the remaining 70% either had no welfare publications or were of an unknown species. With aquaculture growth outpacing welfare knowledge, immediate efforts are needed to safeguard the welfare of high-production, understudied species and to create policies that minimize welfare risks.

Physiology: An Important Tool to Assess the Welfare of Aquatic Animals

Simple Summary

Ensuring a good quality of life for animals is a matter of concern. Welfare assessment has been quite well developed for many terrestrial species, but it is less well characterized for aquatic animals. Classic methodologies, such as behavioral observation, seem unable to improve the wellbeing of aquatic animals when used alone, mainly due to the large number of species and the difficulty to obtain comparative results among taxa. For this reason, it is necessary to identify more methodologies that may be common to the main aquatic taxa of interest to humans: Fish, cephalopods, and crustaceans. Here we present a physiological framework for these taxa as a proxy to evaluate aquatic animal welfare. Physiology is a useful tool in this regard, since animals maintain their homeostasis in a range of values determined for each parameter. Changes occur depending on the type and degree of stress to which animals are subjected. Therefore, understanding the physiology of stress can offer information that helps improve the welfare of aquatic animals.

Abstract

The assessment of welfare in aquatic animals is currently under debate, especially concerning those kept by humans. The classic concept of animal welfare includes three elements: The emotional state of the organism (including the absence of negative experiences), the possibility of expressing normal behaviors, and the proper functioning of the organism. While methods for evaluating their emotions (such as fear, pain, and anguish) are currently being developed for aquatic species and understanding the natural behavior of all aquatic taxa that interact with humans is a task that requires more time, the evaluation of internal responses in the organisms can be carried out using analytical tools. This review aims to show the potential of the physiology of crustaceans, cephalopods, elasmobranchs, teleosts, and dipnoans to serve as indicators of their wellbeing. Since the classical methods of assessing welfare are laborious and time-consuming by evaluation of fear, pain, and anguish, the assessment may be complemented by physiological approaches. This involves the study of stress responses, including the release of hormones and their effects. Therefore, physiology may be of help in improving animal welfare.