Swimming Prawns in Gamtoos

I went fishing at the Gamtoos and stayd the night. To my surprise, i drifted into a swimming prawn frenzy. I saw +- 5kg cobb's, hitting them all the way at the top. I started jigging in between them, and got some nice fish. Kept the 6kg one but released the other 4. Is this a regular Occurance?
 
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