World Aquatic Animal Day: Giving guitarfish the spotlight they deserve!
This year, April 3rd marks the annual World Aquatic Animal Day, which aims to bring light to the multitude of challenges faced by marine and freshwater animals globally whilst highlighting their diversity and environmental importance.
The Center for Animal Law Studies project poster for this year's World Aquatic Animal Day, where the topic focuses on ‘Disentangling the Sustainability Myth in Fishing and Aquaculture’.
When thinking of aquatic animals it is hard not to naturally consider the charismatic creatures many associate with our oceans such as playful dolphins, graceful turtles, singing whales and chattering seabirds. For us at ELMO, it is sharks, rays and skates that hold our interest. However, whilst it is tempting to focus on the great whites and bull sharks roaming our seas, there is one elasmobranch group that deserves the spotlight this World Aquatic Animal Day - the guitarfish!
Guitarfishes are actually considered as part of the ‘ray’ (and not shark) group, because they are flat-bodied with cartilaginous skeletons, just like stingrays. There are a total of 55 species, 8 of which can be found in South African waters. These South African species include common ones like the bowmouth guitarfish, giant sandshark and lesser guitarfish, as well as lesser known ones such as the bluntnose, greyspot, slender and speckled guitarfishes (Ebert et al. 2021). These animals are extremely diverse in appearance, some appearing sleek and flat, camouflaging well with their environment whilst others boast distinctive patterns and morphology such as the bowmouth guitarfish pictured on the right by one of our very own ELMO citizen scientists, Dylan.
In terms of habitat, guitarfishes favor sandy environments in warm and shallow coastal waters. These habitats, however, are particularly vulnerable to fishing pressures as large trawls and gillnets are able to be used easily. Guitarfishes are also financially high in value, with fisheries utilising them for their fins and meat. Seine net-trawling, whilst not used to directly target guitarfishes, still entraps them in the large nets as by-catch. Their habitat use overlaps with many inshore fisheries, increasing their vulnerability to population decline and even leading to local extinction of certain species (Moore, 2017). This is a catastrophic result of large scale fisheries operating within guitarfish habitats that offer little refuge and shelter.
Recreational angling of guitarfish is extremely popular too, with 7621 of the lesser guitarfish species being caught during angling competitions along the Western Cape from September 2011 to March 2020 (Western Cape Shore Angling Association unpubl. data). Although these animals are often released alive, it is unsure how many of these animals survive post-release. As a result of these fishing pressures, combined with a multitude of alternative threats, such as habitat destruction and lack of species knowledge, 70% of all guitarfish fall within the threatened categories of the IUCN Red List or are simply Data Deficient due to problematic species identification and lack of conservation appeal.
A lesser guitarfish captured and released by Marine Dynamic interns, recording weight, length and sex with DNA clippings taken for genetic studies to aid research and conservation efforts of sharks.
Guitarfish hold great environmental importance to the ecosystems in which they live, playing a role as both predator and prey. Bull sharks, sevengill sharks and great hammerhead sharks, all residing off the southern African coast, have been known to prey on guitarfish, providing an important food source for these apex predators. Guitarfish themselves have been recorded to consume a great amount of benthic invertebrates within South African lagoons (Moore, 2017), allowing these sandy ecosystems to be balanced and healthy.
The lesser guitarfish, pictured on the left by citizen scientist Ralph Watson in Uilenkraal estuary, is the most common species within South Africa, distributed from estuaries and coastal bays of Namibia to Kwa-Zulu Natal. Despite it being one of the most commonly spotted species, it is categorised as Vulnerable by the IUCN Red List of Threatened Species with a declining population trend. They feed on benthic invertebrates including crustaceans, mussels and worms in shallow, sandy bottomed waters. Their pupping season occurs this time of year from March to April where they will move further inshore. If you find yourself in or near the water of coastal bays or estuaries, keep a sharp eye out for these animals as they enjoy a game of hide and seek!
Lesser guitarfish showing off its impressive camouflage skills in Simonstown, spotted by the sharp eye of ELMO citizen scientist Kareema.
Whilst we are lucky to know the location and distribution of the lesser guitarfish, the same cannot be said for most other guitarfish species. This is where your role as citizen scientists becomes paramount to improving our understanding of these threatened animals. Locating areas of distribution and understanding the population density will allow a push for improved conservation to protect these underrated elasmobranchs, ensuring our South African species don't face the fate of extinction that has occurred for other global guitarfish. Submit your sightings via the ELMO app and help ensure safety and stability for guitarfish in South Africa!
References and further reading resources:
Lesser Guitarfish Tagging at Uilenkraals Estuary: https://marinedynamics.org/academy/2021/02/24/lesser-guitarfish-tagging/
World Aquatic Animal Day: https://law.lclark.edu/centers/animal_law_studies/animal_law_clinics/aali/worldaquaticanimalday/
Moore, A. B. (2017). Are guitarfishes the next sawfishes? Extinction risk and an urgent call for conservation action. Endangered Species Research, 34, 75-88.
Ebert et al. (2021). An annotated checklist of the chondrichthyans of South Africa. Zootaxa 4947 (1).