why did santiago want the marlin to jump

Santiago wanted the marlin to jump, so he would become tired. 

"Never have I had such a strong fish nor one who acted so strangely. Perhaps he is too wise to jump. He could ruin me by jumping or by a wild rush. But perhaps he has been hooked many times before and he knows that this is how he should make his fight. He cannot know that it is only one man against him, nor that it is an old man."