The Welfare Concept - Does It Apply to Fish Too?
World Small Animal Veterinary Association Congress Proceedings, 2017
Laura D. Urdes, DVM, PhD, PgDip, CertAqV
Assistant Prof., Basic Sciences in Animal Husbandry and Food Industry Faculty of Engineering & Administration of Animal Products, University of Agricultural Sciences and Veterinary Medicine of Bucharest, Romania

A general understanding of the term “welfare” is that it refers to the state of an individual’s body and mind, in relation to its environment. Although still controversial, due to the many conflicting aspects, welfare of animals is commonplace today, in most parts of the world. Mankind has made huge progress towards understanding animal welfare: from seeing animals as non-humans lacking consciousness, used as objects, with little concern for their welfare, we have arrived now to the point where there is increasing concern for, and interest in understanding welfare of all non-human animal species, including fish and non-vertebrates. The first known organisation devoted to animal welfare, The Society for the Prevention of Cruelty to Animals, formed in 1824, in London, aiming at educating people about animals. Forty years later, The American Society for the Prevention of Cruelty to Animals (ASPCA) was established, followed by a number of states and territories within the United States issuing laws against cruelty to animals. Charles Darwin’s Origin of Species (1859) and Descent of Man (1871), which initially stirred great controversy, as it was raising the status of animals by presenting evolutionary links between humans and other animal species, had narrowed the gap between people and other animals, so that the new concept was accepted in the late 1800s by most educated people. By the beginning of 1970s, people became aware of existing relationships between living things and their environment. The idea that humans depend on the nature, and that their health and quality of life rely heavily on the quality of environmental components had hit forcefully in the late 1960s, bringing the science of ecology to the light and making people aware of the fact that humans do not rule over nature, but rather are part of it. As Laurence Pringle mentions in his book, The Animal Rights Controversy (1989),1 the concept of ecology meant to most of the public avoiding mismanaging of the environment by reducing pollution, protecting wildlife habitats and saving endangered species. This was also the time that the animal rights movement emerged, demanding animals’ freedom from “human oppression” and consideration for non-human animals. As expected, this movement brought about a revolutionary change of the ways humans used to feel about, and dealt with animals, but this was also the starting point of a continuing controversy on what non­human animals, and to what extent animal welfare should be considered. While advocating for “equality” and “wellbeing” of animals, Peter Singer, in his book, Animal Liberation (1978)2 reasons that it all comes down to the capacity of suffering and enjoying life. But since suffering and pain are “mental events” perceived at individual level, one cannot tell what these events are to others. In their majority, most mammals and birds would express pain and other suffering feelings by screaming, crying, writhing, etc., while they can also be seen playing and taking pleasure in various aspects of their life. This behavior has been proved as with scientific basis in that they have nervous systems responding to stimuli in ways similar to those of humans. Thus, there is good reason to assume that many animal species have the capacity to suffer or experience pleasure and hence, their welfare should be considered. However, if we follow only the two conditions highlighted above, based on proves and links for feelings expression in animals (i.e., behavior and anatomy/physiology of CNS), it may drive us on a wrong path. Relying on the thinking that species which do not seem to show feelings, as well as those of which the CNS structure has not been proved to relate to the nervous system peculiarities of phylogenetically evolved species, would ensure exclusion of all animal classes or groups placed in the phylogeny of species underneath birds, including fish, crustaceans, and mollusks, that may prove wrong. If we take octopus, a mollusk (invertebrate) as an example, which has a very complex nervous system, being capable to show emotions and cleverness beyond expectations, we will see that it does not conform to the description of above. Fish and crustaceans are today being considered eligible for welfare considerations, although certainly, neither of those species conform to the description described previously. This is where indicators of stress, indirect monitors of suffering and happiness of most animal species, come into discussion.

Poor welfare conditions can be assessed by accounting for the biology of the fish and how far the individual has deviated from the normal conditions. Generally, water quality parameters, management procedures, the design of tanks and handling procedures of fish - on one hand, and fish density, feeding, and individual factors such as genetics and disease resistance - on the other hand, are most commonly used indicators of fish welfare. Generally, signs of homeostasis disruption expressed as morphological and swimming abnormalities, outbreak of (parasitic) diseases, loss of condition, etc., are generally suggestive of poor fish welfare. Hematological, biochemical and non-specific immune parameters have also been assessed to identify poor welfare of fish through starving.3 Blood hematocrit and hemoglobin, plasmatic cholesterol, cortisol, aspartate aminotransferase, alanine aminotransferase, glucose, plasma total protein concentrations, and plasma lysozyme concentrations have been studied to find correlations between these conditions in fish and poor welfare. However, the results showed adaptation of the metabolic profile of starved fish which is not suggestive of alarm-stress response. The most common stress indicator, the glucocorticoid hormone cortisol, has been proved to reach increased levels in stressed animals, leading, assumingly, to stimulation of protein catabolism, lipolysis, and gluconeogenesis. Although viewed as an important welfare impairment indicator in fish, cortisol has little value if fish welfare is regarded from behavioral perspective and on single time point measurements, as it is considered rather a natural, adaptive response to environmental conditions and husbandry practices. Cortisol releases cannot be predictable, requiring a number of variables to be accounted for, such as diurnal and seasonal variations, as well as genetic and environmental factors. Fish studies indicate as areas of clarification for the use of cortisol as fish welfare indicator, separation of chronic stress from acclimatization and identification of the relation between feelings, cortisol, and behavior of fish.4,5

Scientific studies to assess fish welfare are continually evolving. The challenge includes the great diversity of fish species and production systems, while relevant scientific data in this field are still missing. In the European Union, the Council Directive 98/58/EC lays down minimum standards of protection for animal species bred or kept for farming purposes, including fish. In 2005, the Council of Europe adopted a recommendation on the welfare of farmed fish. Three years later, the OIE adopted guiding principles for fish welfare. The EFSA Panel on animal health and welfare (AHAW) adopted in 2009 an overall approach regarding fish welfare, including welfare aspects of stunning and killing methods for seven species of farmed fish.

All aspects relevant to fish welfare will be systematically discussed during the presentation.


1.  Pringle L. The Animal Rights Controversy. NY: Harcourt Brace Jovanovich Publishers; 1989.

2.  Singer P. Animal Liberation: A New Ethics in Our Treatment of Animals. NY: Random House; 1975.

3.  Kim JH, Jeong HM, Jun JC, Kim TI. Changes in hematological, biochemical and non-specific immune parameters of olive flounder, Paralichthys olivaceus, following starvation. Asian-Austra Jas J Anim Sci. 2014;27(9):1360–1367. doi: 10.5713/ajas.2014.14110.

4.  Ellis T, Yildiz HY, López-Olmeda J, Spedicato MT, Tort L, Øverli Ø, Martins CI. Cortisol and finfish welfare. Fish Physiol Biochem. 2012;38(1):163–188. doi: 10.1007/s10695–011–9568-y. Epub 2011 Nov 24.

5.  Gräns A, Niklasson L, Sandblom E, Sundell K, Algers B, Berg C, Lundh T, Axelsson M, Sundh H, Kiessling A. Stunning fish with CO2 or electricity: contradictory results on behavioral and physiological stress responses. Cambridge University Press. Animal. 2016;10(2):294–301. Published online 2015 May 11. Doi: 10.1017/S1751731115000750.


Speaker Information
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Laura D. Urdes, DVM, PhD, PgDip, CertAqV
Basic Sciences in Animal Husbandry and Food Industry
University of Agricultural Sciences and Veterinary Medicine of Bucharest
Bucharest, Romania

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