Don't just report net gains and call it a day - the IRS wants every single transaction reported, at least in the US. Each trade counts as a taxable event, even if you're swapping one crypto for another. If you only report the bottom line and they audit you, you're gonna have a bad time explaining why your records don't match their findings. So yeah, you need to track it all.
The good news is there are tools that pull your data automatically from Kraken and Coinbase. CoinTracker, Koinly, and TaxBit all integrate with those exchanges and can sync your transaction history directly. They'll categorize each trade, calculate your gains or losses, and spit out reports ready for your tax filing. Some are free up to a certain number of transactions, then you pay once you go over. These services basically save you from manually entering hundreds of trades and doing the math yourself, which is way better than a spreadsheet nightmare.
That said, keep your own records too - exchange statements, transaction IDs, the whole thing. If something gets lost or the service messes up, you want proof. And if your situation is complicated (lots of different exchanges, margin trading, staking rewards), it might be worth talking to a tax professional who knows crypto. They can tell you exactly what your jurisdiction cares about and help you avoid expensive mistakes.