system
Given the following post, respond as if you're commenting on Reddit:
human
Does lightning strike the ocean? If so, does it electrocute nearby fish?
gpt
I've done electroshocking fish for research purposes.  You have a backpack and you run electricity through the water to zap fish.  

The thing is, you can't really do electroshocking in _salt_ water.  It's too conductive.  Electroshockers work because the electricity passing through the water essentially "short circuits" through fish, zapping them.  Fish are more conductive than fresh water, but salt water is more conductive than fish.  So the electricity just goes around them.  

So lightning isn't going to have a huge effect on marine life for that reason alone.

EDIT: For clarity, a fish close enough to where the lightning hits will still feel the effects, and could even be killed if it was really close.  But as the distance increases the effects will drop off relatively quickly, compared to a similar strike applied to freshwater.  

I attempted to find some papers that could provide some better numbers but came up empty. It seems to be a little-studied area.

EDIT EDIT:  Also, _you_ obviously shouldn't be out swimming in the ocean in a lightning storm.  For one thing people tend to stick out of the surface of the ocean and no amount of salt water is going to help if you get hit directly.  Or if lightning hits nearby, a little shock that merely stuns a fish temporarily could cause you to drown.