YELLOWFISH WORKING GROUP - YWG Newsletter: February 2017

Dear All,

Herewith the news for this month:

 

Proposed use of Rotenone in the Krom River, Cederberg  Western Cape.

The Krom river was one of the four rivers identified by CapeNature and fish conservation stakeholders in the mid 2000’s for alien fish control to help save threatened fish species of the fynbos region from extinction. These rivers were the Krom (Cederberg), upper Krom (Joubertina), Rondegat and Suurvlei rivers. In summary, it is proposed that the middle/lower section of the Krom River, which is seasonal in Summer, between the recently constructed upper barrier at Kromrivier farm and a lower natural barrier in the Matjies River Nature Reserve be treated with this piscicide if approval from Water Affairs is obtained, so as to remove the alien/invasive fish which are mainly largemouth bass and small numbers of bluegills. There are also possibly a few rainbow trout in the very deep pools. The objective is to introduce indigenous fishes that likely occurred in the catchment (e.g. Doring fiery redfin, Clanwilliam sandfish, Clanwilliam sawfin) according to a IUCN translocation plan and provide a sanctuary for them in the 6,3 km between the two barriers.

This Krom River project will follow the very successful use of rotenone by CapeNature in the Rondegat River which is also in the Cederberg. The landowners of Kromrivier farm are very conservation conscious and have produced a range of craft beers with indigenous fish names such as chubbyhead stout. They are keen to see indigenous fishes return to the river.

To access the EIA which was published for comment this month please click on click here

It is interesting to note that CapeNature state that there is no plan to treat the upper section of the Krom with a piscicide anymore. This upper section is about 6 km long between the artificial barrier at the farm and a waterfall at the upper end. Rainbow trout were introduced in 1950 and although they are thought to have eradicated the fiery redfin in this section the Clanwilliam rock catlet has maintained a good population with trout as it is a nocturnal species and adults are too big to be eaten by trout. In the last couple of years nearly 400 rainbow trout were removed by a CapeNature contract team using nets and by angling to reduce the trout population. CapeNature plans to keep the trout population as low as possible using mechanical removal methods, once bass and bluegill have been removed from the treatment area to enable fast recovery of indigenous fishes once they are introduced into the catchment.

Regards,

Peter

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