I think there may have been an attempt to capitalize on the success of a recent movie.
There's not much suspense when it comes to Superman vs. Jaws. He could pick up Jaws and throw him into space.
It should be noted that the shark had not heard the lyrics to Jim Croce's "Mess around with Jim" song, because tugging on Superman's cape was one of the things one simply did not do.
The shark had good timing, though. We also learn that shark's teeth are capable of penetrating the cape of the superbeing; I thought it was made out of something industructible. But it makes sense for it to be tear-away; otherwise you're always getting snagged.
This is from that regrettable period of Action comics when Superboy's neck was implanted with the genes of Plastic Man.