REPORT 04/06/2020 Reg. no. 5.2.18-00981/2018 Fish identification Marking and tagging methods Michael Axelsson, University of Gothenburg, Department of Biological and Environmental Sciences Erik Peterson, Swedish University of Agricultural Sciences, Department of Aquatic Resources Albin Gräns, Swedish University of Agricultural Sciences, Department of Animal Environment and Health Per E Ljung, the Swedish 3Rs Center The Swedish 3Rs Center is a part of the Swedish Board of Agriculture [email protected] │ Twitter: @Swedish3Rs 1 Contents Background ...................................................................................................... 3 Things to consider when marking and tagging ............................................ 3 Education, training and ethical approval for animal research ............................................................. 3 Work environment considerations ....................................................................................................... 4 Anaesthesia .......................................................................................................................................... 4 Known impacts of having a tag ........................................................................................................... 4 Methods ............................................................................................................ 6 Symbols and their meanings ................................................................................................................ 6 Brief description of the methods ......................................................................................................... 7 Guide for when you need to be able to distinguish between individuals ............................................ 8 Guide for when you do not need to be able to distinguish between individuals ................................. 9 Biotelemetry/biologger – internal...................................................................................................... 10 Biotelemetry/biologger – external ..................................................................................................... 11 Carlin tags ......................................................................................................................................... 12 Chemical branding ............................................................................................................................ 13 Clipping the adipose fin .................................................................................................................... 14 Clipping the maxilla .......................................................................................................................... 15 Clipping the pelvic fin ....................................................................................................................... 16 Coded-wire tags ................................................................................................................................. 17 Dart tags ............................................................................................................................................ 18 Freeze branding ................................................................................................................................. 19 Genetic identification ........................................................................................................................ 20 Microchip (PITtag, RFID) ................................................................................................................. 21 Natural patterns and unique markings ............................................................................................... 22 Otolith marking ................................................................................................................................. 23 P-chip ................................................................................................................................................ 24 Short-term marking with plastic beads or filaments .......................................................................... 25 Spaghetti tags .................................................................................................................................... 26 Spray marking ................................................................................................................................... 27 Streamer tags ..................................................................................................................................... 28 Tattoo methods .................................................................................................................................. 29 T-bar anchor tags ............................................................................................................................... 30 VI alpha tags ...................................................................................................................................... 31 VIE (Visible Implant Elastomer)....................................................................................................... 32 References ..................................................................................................... 33 The Swedish 3Rs Center is a part of the Swedish Board of Agriculture [email protected] │ Twitter: @Swedish3Rs 2 Background In order to be able to study fish movement patterns, population dynamics, different physiological variables or to be able to track an individual over a period of time, it is often necessary to be able to identify an individual fish for a shorter or extended period of time. This can sometimes be done using the animal’s natural patterns and other unique markings. In other cases, the animal must be marked or tagged in some way, which often involves a certain degree of handling and/or surgery. A number of scientific studies have been done to evaluate different marking and tagging methods. Several other documents describe and compare different methods, including a Swedish report on different marking and tagging methods for salmonids. A scientific compilation of identification methods for small fish was also recently published. But there is a lack of easy-to-follow guidance that considers the welfare of fish, economic aspects and the user’s perspective. There is a demand for this type of guidance, from the regional ethical committees on animal experiments and other groups. On behalf of Sweden’s National Committee for the Protection of Animals used for Scientific Purposes we have reviewed commonly used methods of marking, tagging and identifying fish. The report contains methods that are suitable for use in lakes, watercourses and seas, but also controlled environments, such as aquariums, fish farming cages or laboratory environments. For each method reviewed here, we go over the most important factors for the user and the impact on the fish. We have listed the references we used by title and method at the end of the report. The purpose of the report is to assist the user in choosing the most suitable method and should therefore not be seen as a comprehensive handbook for marking and tagging fish. Our goal in publishing this report is to help ensure that the correct marking and tagging methods are used for the right purposes, thereby contributing to a reduction in the negative impact on the animals and reducing the number of animals used. Things to consider when marking and tagging There are more than 34,000 fish species across the world, and since their morphology, physiology and behaviour vary, these factors needs to be considered when choosing a marking or tagging method. It is also important that fish capture and handling is well planned and done as quickly and gently as possible. Many fish species are covered by a protective mucus layer, and it is therefore important that all handling is done in a way that has as little impact as possible on the mucus layer. For example, if netting is necessary, only knotless, silicone-coated nets should be used. Sock nets, where the fish are not exposed to air at all, are optimal. If fish are handled by hand, it is important that your hands are wet or that you use latex gloves or similar. It is also important to minimise the amount of time fish are exposed to air, especially if the species is sensitive to air exposure. In many cases, the fish must be anaesthetized before marking or tagging. Some fish, such as eels and carp, are less sensitive to air exposure, but if the handling and the marking or tagging procedure takes longer than 10 seconds, the fish should normally be ventilated by flushing oxygenated water over the gills during the procedure. During surgical procedures it is important to work with clean, sharp instruments and clean surfaces to minimise the risk of infection. The instruments, including cannulas, must be disinfected with 70% alcohol or with other disinfectants, such as Cidex. Education, training and ethical approval for animal research For simpler procedures, you should have completed a fish marking and tagging course, preferably a course with the content described in SJVFS 2019:25, Chapter 5, Section 4, which in Sweden is given by the Swedish University of Agricultural Sciences. For the more advanced procedures, such as the implantation of devices in the abdominal cavity, you should also have attended an LAS (Laboratory