Fish Tagging

After 30 years, this project is still going strong and is undoubtedly one of the most enduring and successful environmental projects of its kind in South Africa. It involves the cooperation of conservation-conscious anglers (i.e. anglers who voluntarily tag and release their fish) and the marine angling public at large, who report the majority of the recaptures (i.e. a fish that is recaught with a tag in it) to ORI.

Despite the voluntary nature of this project, the tagging of fish still has great scientific merit, allowing us to learn more about the movement patterns, growth rates, mortality rates and population dynamics of our important linefish species. This information is extremely valuable and is used by scientists and managers around the country for policy and decision making on linefishery management. Despite the large quantity of important scientific data collected by this long-term project, the tagging project has also made a major contribution towards changing the ethics of anglers with regard to catch-and-release, which undoubtedly goes far beyond the pure scientific value of the data collected. Not only do anglers now have a reason to capture and release a fish, they are in actual fact contributing to a better understanding of the biology and ultimately the conservation of that species. This added bonus goes a long way in improving angler awareness about our marine linefish species, as well as contributing towards sustainable fishing.

There are many different types of tags used on different fish species (e.g. PIT tags, satellite tags, acoustic tags, archival tags, etc.); however, the most common method is conventional tagging and involves the use of external dart tags, which are the preferred type used in the ORI-CFTP. Each tag consists of a monofilament vinyl streamer attached to a plastic barb, much like a miniature version of a spear from a speargun (Figure 1). Each tag is inscribed with a unique alpha-numeric code (e.g. D123456) and contact details (i.e. email address, cell phone number and postal address). Tags are generally inserted with a sharp, hollow, stainless steel applicator, into the dorsal musculature of a fish or shark, although this may differ in certain fish species (e.g. rays). Upon initial tagging (and subsequent recapture of a tagged fish) anglers record the following information: fish species, length (fork or total), tag number, exact locality and date.

The use of external tags by the ORI-CFTP is particularly favourable as it is relatively cheap compared to other tagging methods, relatively little training is required to insert tags, no software is required to download information from each tag, and the tagging equipment is very basic. This allows a relatively large number of fish to be tagged at little cost and allows citizens who are not trained scientists to be involved. However, considerable attention has been focused on ensuring that the best available tag and tagging equipment is used and that our taggers are shown how to handle and tag fish correctly, in order to minimize post-release mortality.