ORI celebrates 30 years of citizen science through its tag-and-release project
On 25 August 2015, the uShaka Sea World Education Centre welcomed a variety of guests all connected in some way to the Oceanographic Research Institute’s (ORI) Cooperative Fish-Tagging Project (ORI-CFTP).
Guests arrived from as far afield as Cape Town and Grahamstown to celebrate 30 years of citizen science through the marine fish tag-and-release project. One intrepid tagger even drove from East London to take part.
In what was a very relaxed but informative gathering of what felt like old friends, senior scientist Bruce Mann and assistant scientist Stuart Dunlop, both from ORI, gave a brief overview of some of the history and achievements of the ORI-CFTP. In addition, leading scientists Professor Paul Cowley from the South African Institute for Aquatic Biodiversity and Associate Professor Colin Attwood from the University of Cape Town gave excellent presentations on some of the fish-tagging work they have been conducting in the Eastern and Western Cape respectively.
The ORI-CFTP was the brainchild of internationally recognised scientist and past ORI director, Rudy van der Elst. Rudy realised the potential for a well-managed cooperative fish-tagging project to generate much-needed data on linefish and, being spurred on by a growing concern among anglers of poor fish catches, the ORI-CFTP was launched in 1984.
Three decades later the 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 (anglers who voluntarily tag and release their fish) and the marine angling public at large, who report the majority of the recaptures (a tagged fish that is recaught) to ORI.
Despite the voluntary nature of this project, the tagging of fish still has great scientific merit, allowing us to learn more about 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 actually contributing to a better understanding of the biology and ultimately the conservation of that species. This added bonus goes a long way towards improving angler awareness about our marine linefish species, as well as contributing to sustainable fishing.
There are many different types of tags used on different fish species (PIT tags, satellite tags, acoustic tags, archival tags, etc.) but the most common method is conventional tagging that 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, and each tag is inscribed with a unique alphanumeric code (e.g. D123456) and contact details (email address, cellphone 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 such as 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 – minimal 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 enables citizens who are not trained scientists to be involved, which is similar in some respects to the South African Bird Ringing Unit.
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 minimise post-release mortality. Since 1984 around 5 500 members have joined the ORI-CFTP, accounting for the capture, tagging and release of an incredible 285 177 fish, mostly in South African coastal waters, but also occasionally in Mozambique and Namibia. Note should be taken that this represents 285 177 fish that were released to "fight another day" and hopefully reproduce for future generations.
Of the fish tagged, 15 915 (5.6%) have been recaptured and reported to ORI. Our top five fish tagged include galjoen (59 218), dusky kob/kabeljou (16 799), leervis/garrick (13 424), dusky sharks (12 499), spotted grunter (10 963) and copper/bronze-whaler sharks (9 153).
Unfortunately, a large proportion of recaptured fish are not reported to ORI, which would, with greater awareness, undoubtedly increase the recapture rate substantially. If you see or hear of any angler who has caught a tagged fish, please offer to assist them in recording the relevant information (tag number, species, correct length measurement, exact locality, date, angler name and contact details, and whether the fish was kept or re-released) and even offer to send the information in to us on their behalf via email to firstname.lastname@example.org, or by calling +27 (0)31 328 8222, or via SMS to +27 (0)79 529 0711.
Over the past 30 years there have been some amazing recaptures reported to ORI. The fish species with the highest recapture rate is speckled snapper with 1 893 fish tagged, of which a remarkable 804 (43%) have been recaptured, owing largely to its highly resident behaviour. Galjoen, our national fish, is the most tagged species on the project, with 59 218 fish tagged, accounting for 21% of the total number of fish tagged to date.
Much of this is thanks to the efforts of the research team that has been tagging galjoen in the De Hoop Marine Reserve since 1987 and some avid taggers fishing along the Cape Peninsula. The longest recorded time free (the length of time a fish was at liberty between the initial tagging and first-time recaptured) for a bony fish was a red steenbras tagged in the Tsitsikamma National Park in 1989. This fish was recaptured off Kei Mouth in the Eastern Cape in 2011, some 22 years later, providing strong evidence of the longevity of this species.
Similarly, a ragged-tooth shark tagged at Southbroom on the KwaZulu-Natal South Coast in 1988 was recaptured in Mossel Bay in 2011, a staggering 23 years later and 1 014 km away from its original tagging location. The most recaptured individual fish on the project is "Rocky", a yellowbelly rock cod tagged in the Pondoland MPA just south of Port Edward, which has been recaptured nine times on the same reef over a three-year period.
It is these incredible recaptures and the numerous others on the tagging database that make this project so exciting and beneficial. We would like to express our sincere gratitude for the financial and administrative support received from the following organisations during the 30-year history of this project: the South African Association for Marine Biological Research; the Stellenbosch Farmers' Winery (now called Distell), which generously funded the tagging project for 22 years under its Sedgwick’s Old Brown Sherry brand; the South African Nature Foundation which became WWF-South Africa; the Tony and Lisette Lewis Foundation; and most recently the KwaZulu-Natal Department of Economic Development, Tourism and Environmental Affairs, without which we would have been unable to continue this important project.
Most of all, we would like to thank all of our past and currently active tagging members for their valuable contributions towards this project. David Hall (Hallprint© Australia) is thanked for his excellent service and ongoing supply of high-quality tags and applicators. Lastly, we would like to thank Rudy van der Elst for his foresight in developing this remarkable “citizen science” project long before the coining of the phrase; and to Elinor Bullen for running the project as ORI’s “tagging officer” for an incredible 27 years (1984 to 2011)!
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