What exactly does 硬 mean here?
硬 here connotes forcefully, without any tactics and etc. 

硬捉 means to capture/seize/catch merely by force, without any tactics.

So, 


  看来，硬捉是不行的，不如换个方法！ 
  
  Looks like, the way of capturing forcefully (without any tactics) wouldn't work, so we might as well change/turn to another way.  


The synonym of 硬 in this context can be 强.