Where can I find spatial data on polar fish populations? I am looking specifically for polar cod, but any fish will do at this point in my project. I also need arctic ocean salinity, temperature, and sea ice coverage
Not sure if it fits within the scope of your project but good fish data at the worldbank:
You might also want to check the Fish and Wildlife Department for whatever state/area you are in.
The Alaska Fisheries Science Center looks to have good data:
I've found that even if you can't find what you are looking for on the websites, calling these governmental organizations can be very helpful. Most all of the information they would have is public record, and most of the time, they are happy to help. Especially when it comes to science stuff and environmental projects.