Hammer Shark / Silver Shark

[KikoriL]

You don't have to use sardines in specific. You can catch Merlthor Goby off the South Bloodshore (in my case with a floating minnow jig) to mooch for Silver Shark there as well, and since it's a level 25 location, you'll have more luck getting high quality Goby. The downside is you'll have more types of fish to get after a Mooch. Cape Westwind is good if you're a high level fisherman, but anything lower will slash your HQ Goby chance significantly.
EDIT: The coral butterflies and blue coral are also pretty nice to catch from Bloodshore, too.