Taking science to recreational fishing

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Rhodes University’s Department of Ichthyology and Fisheries Science recently initiated a “community engagement” partnership with a competitive fishing body known as the Rock and Surf Super Pro League (RASSPL). The long-term aim of the partnership is to minimise the environmental impact of the league.

Over the weekend a team of fourteen staff and students embarked on an experiment to examine the effects of catch-and-release during a competitive angling event on the health and survival of fish. The team, led by Dr Warren Potts, spent three days in the Border area at the annual Rock and Surf Super Pro League (RASSPL) national fishing competition. The event saw anglers from the Western Cape, Southern Cape and 3 teams from the Eastern Cape, take to the beach from Thursday 30 April to Saturday 2 May for individual and team bragging rights.

While the anglers set to work on their fishing strategies, the research crew got going on each of the three aspects of the experiment. Researchers were placed throughout the fishing area to observe fishermen’s behaviour, recording the time for different events that occur when hooking, fighting, landing, measuring, photographing, and releasing fish, paying particular attention to how long the fish were exposed to air, an extremely stressful event for fish comparable to holding your head in a bath of water after running a 400m race. Once fishermen completed their tasks for recording their catch, researchers received the fish into a tub of water.

Various observations were made to determine the state of stress of the fish following the catch-and-release event. These observations included noting the rate of gill movement, whether the fish responded to being grasped around the tail, how long they took to right themselves after being inverted, and whether they flexed their bodies when suspended above the water on open hands. Each event was given a score and the total of these scores indicated the level of stress which that fish was in.

Parallel to these stress observations, blood samples were collected to test for glucose and lactate levels, widely used as indicators of stress in similar studies. On the 3rd day of the competition, fish were collected from the fishermen and placed into 1 of 3, 3 kl ponds to determine their survival rate. Forty fish were held overnight. All fish survived except for 5 fish of 2 different species of sea catfish – 4 of 10 white sea catfish and 1 of 3 black sea catfish died. This may indicate that these species are good indicator species that can be used to monitor survival of fish after being handled by fishermen.

The Department is rapidly developing its recreational fisheries research portfolio. Besides the long-term RASSPL project, several other recreational fisheries research projects have been established during the last year. This includes a global review project of recreational fisheries governance funded by the FAO, a two year project that aims to assess the economic impact of South Africa’s recreational fisheries in partnership with the University of the North West, University of Cape Town, SAIAB and the Oceanographic Research Institute. The Department has also established a partnership with WWF in their citizen science project “fish for life” and will be conducting one component of the project “Fishtory”, which aims to create an online platform to digitise historical angling photographs and generate historical data from fishermen throughout the country. Another project funded by the Department of Trade and Industry will examine the impacts of climate change on several of South Africa’s recreational linefish species.

Source:  Communications and Marketing

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