Creating greater awareness of the global importance of freshwater migratory fish

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Rivers have been manipulated for centuries for many reasons. Dammed rivers provide water for cities, irrigation for crops and massive economic drivers, such as the generation of power.

Locally, we have been manipulating our waterways with artificial structures since the 17th century. Indeed, the country was one of the leading dam builders in the world. Our estimated 500 large dams hold back millions of litres of water, enabling activities that would otherwise have been well-nigh impossible in a semi-arid climate.

Dam construction started slowing down here in the 1970s, in part because there was a growing realisation that the benefits also came with a price – often to the detriment of the river environment.

One area of concern was, and still is, our migratory fish and invertebrate species. Barriers to migration in rivers, such as bridges, weirs and dams, are considered a major factor responsible for the reduction in numbers and range of many species throughout the country. Locally, we have about 100 indigenous freshwater fish species that undertake annual migrations to reach better feeding grounds, avoid unfavourable conditions and improve breeding success.

To create more awareness of this situation, the world’s first World Fish Migration Day was launched on May 24. It aims to promote greater awareness of the global importance of freshwater migratory fish and free-flowing rivers.

The concept is the brainchild of Dutch aquatic ecologist, Dr Herman Wanningen and a number of international organisations, including the WWF in the Netherlands, the nature conservancy in the United States and the IUCN SSC/Wetlands International Freshwater Fish Specialist Group and Wanningen Water Consult with LINKit consult.

Aquatic health specialist, Dr Kerry Brink, one of the organising partners, explains that it is the first of its kind worldwide and that over 250 events across the globe have taken place to mark the occasion.

Part of the aim is to let people know that there are other alternatives to restore the movement of fish, if the physical construction cannot be removed.

These include fish ways, ladders or passes – structures placed on or around constructed barriers such as dams or weirs to give fish an opportunity to migrate.

Locally, the day was celebrated in the Kruger National Park, and focused on some of the corridors that have been constructed in the rivers.
Consultant Dr Andrew Deacon, who spent the bulk of his career as the park’s freshwater ecologist, organised a tour in the park, including the Leopard Creek ladder, the Lower Sabie gauging weir, the Lower Sabie Dam bridge, which has a near-natural one, and the Kruger Gate gauging weir.

Deacon says there are currently more than 13 in the park, the first of which was constructed on the Engelhard Dam in 1971, providing the only migration route for aquatic organisms over the 667,7-metre-long dam wall with its 329-metre spillway.

As for future plans for the international celebration, the goalpost has been moved further ahead.
The partnership has come up with a letter of intent to cement the future of this international event.
More information: http://www.worldfishmigrationday.com/

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