Sand banks stopping fish

[Mouldz]

In Port Alfred there has been a ongoing dispute with the marina developers and the residents as to the cause of the two massive sand banks blocking the river ,locals ,including me,believe that the marina slows the flow of the river allowing sand to build up.
Anyway that is another issue,what I would like to know is does this "narrowing" of the river stop fish from coming and going out to sea,as over the years catches have dropped significantly especially when it comes to cob,see google pic to see the 2 big sand banks chocking the river

 

[Pixel_Ninja]

I would say yes. Other than the Buffalo River, all our other rivers have gone this route(Bonza Bay; Nahoon; Gonubie) and other than some small kob(talking 30cm fly swatters) legal kob are very very scarce. Doesnt affect the grunter though