Farmed Fish Welfare: Filling In The Gaps

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For many people the word “fish” carries the connotation of innumerable quantities of something utterly foreign — a swarming mass of alien creatures living in a strange land, creatures that don’t quite reach the standard of “animal.” This distinction can be seen in the way people talk about vegetarianism; a vegetarian, by definition, is someone who doesn’t eat animal meat…except, you eat fish, right?  

So it should come as no surprise that our knowledge about fish is limited. The knowledge that we do have is often related to production traits (how to maximize profit). We know next to nothing about welfare, and this is the gap that the researchers behind the FishEthoBase intend to fill.

The FishEthoBase is a database that provides information on the welfare of farmed fish species to be used by the aquaculture industry. This is an increasingly important undertaking as aquaculture, or fish farming, gains more and more traction and popularity. The romantic image of a fisherman out at sea? Forget it. It still exists, of course, but not in any way that is meaningful in the industry. The fishes consumed today are almost exclusively obtained via fish farming, and large scale commercial trawling.

The FishEthoBase is divided into full profiles and short profiles.  The full profiles are an exhaustive review of the behavioral biology of each species, which includes a set of recommendations based on the findings.  All of this data is then summarized in short profiles, which are divided into 10 core criteria.  For each criterion, they compare what’s known about the different fish species  in the wild versus under aquaculture conditions.  The 10 criteria are as follows:

• Home range:  Farmed fish are, of course, confined. Sometimes these dimensions match the fish’s natural behavior, but more often they do not.
• Depth range: All fish farming requires some depth limitation to prevent escape, which can affect fish because of the huge variation in physical and environmental components depending on the depth of the water.  
• Migration:  In farmed conditions, naturally migrating fish are unable to do so.
• Reproduction: Reproduction is induced through hormonal stimulation and invasive procedures, which can harm the fish. 
• Aggregation: Aggregation refers to the number of fishes per unit of space. Densities that are too low can negatively impact schooling species, whereas high density can cause stress or mortality for solitary species.
• Aggression: Some fishes are naturally aggressive or can become aggressive due to the stress of confinement. 
• Substrate and shelter needs: Fish farms are generally barren to comply with hygiene standards, which might negatively affect fishes that rely on shelter or nesting.
• Handling: Manipulation and handling includes cleaning, culling, grading, sexing, transport, vaccination, harvesting, and slaughtering. Handling is the most invasive aspect of fish farming, but also the easiest to improve. 
• Malformations: Abnormalities may be more common in farmed fish due to farming conditions.
• Stunning and slaughter: Humane slaughter is, of course, essential in the measure of welfare. 

For each criterion, the database provides information and scores according to the Likelihood that fish experience good welfare under the lowest standard farming conditions, the Potential for the species to experience good welfare in the highest available standards, and the Certainty of the assessment.  The data is summarized into three welfare scores between 0 and 10 (the higher the number, the better the welfare conditions). 

In October 2018, there were 41 species in the database, and the picture painted is a bleak one.  They found that the average Likelihood score was 0.44 ± 0.02, with no species receiving a positive mark (>5). The average Potential score was 1.37 ± 0.04, with only two species (Nile tilapia and African catfish) receiving a positive score. It seems that these two species are best suited to cope with the conditions of being captive, and the other species may not be suited to cope with aquaculture at all (not, at least, using the methods available today).  Researchers found a positive correlation between Likelihood and Potential, meaning that the fish best able to cope in their current conditions also have the greatest potential to experience good welfare. 

A main takeaway is the lack of knowledge, and the sheer importance of this incomplete knowledge. The average Certainty score was only 1.93 ± 0.04. On average, species were 0.93 points away from their full welfare potential (calculated as Potential minus Likelihood), meaning there isn’t a lot of room for improvement using current farming techniques. Research and new techniques are needed to make a sizable impact. The strong correlation found between Certainty and Potential shows that the more information we have, the greater potential a species has to live in good conditions. 

The goal of the FishEthoBase is a dynamic one, where knowledge is added to the database as science advances, and the aquaculture industry uses this knowledge to shift industry practices. The ultimate goal is, of course, to maximize welfare of farmed fish to the extent possible. Researchers feel that they have barely scratched the surface, but the creation of the database represents an important first step: establishing the importance of measuring fish welfare, and beginning the work to do so.