Voorbij het monsterbeeld: de haai als slachtoffer
Shark species are declining and anthropogenic pressures are on the rise.
This study investigates the occurrence and characteristics of anthropogenic injuries in bull sharks and oceanic blacktip sharks at Aliwal Shoal, Umkomaas, South Africa. The aim is to assess injury frequency, origin, type, anatomical distribution and seasonal variation, as well as the influence of photographic coverage on injury detection.
A total of 383 sharks were analysed, consisting of 53 bull sharks and 330 oceanic blacktip sharks. For bull sharks, 3,975 photographs were systematically reviewed, while 25,354 photographs were analysed for oceanic blacktip sharks. Data was collected using photographic records and classified according to injury presence, number, origin, type and body location. Seasonal patterns were derived from the month of observation and grouped into seasonal categories.
Anthropogenic injuries were recorded in both species, with a substantial proportion of individuals affected. Fishing-related injuries were the most frequent in both bull sharks and oceanic blacktip sharks, followed by vessel-related injuries. Most sharks exhibited a single injury, although multiple injuries per individual were also observed, particularly in oceanic blacktip sharks. Retained fishing gear and associated wounds were the most common injury type, while fins were the most frequently affected body region in both species.
Seasonal variation in newly observed injuries indicated differences in distribution across seasons, with relatively higher frequencies during warmer periods. Photographic analysis showed that a considerable proportion of sharks did not have full-body coverage, suggesting that some injuries may not have been detected and that reported values likely underestimate true occurrence.
Overall, the results demonstrate widespread anthropogenic interaction with sharks at Aliwal Shoal and highlight the importance of fisheries as the main source of injury, as well as the need for improved monitoring methods to better assess impacts on shark populations.
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