I did some reading on what's in place in CA. (Not to say that PA will necessarily be the same, if SIP is ordered, which seems increasingly likely.) Driving to engage in outdoor activities is (as of now) permitted under SIP in CA, provided you drive directly from your home to your destination, and return directly home, and you do not interact with anyone within a 6 foot radius while engaging in the outdoor activity. Hiking and fishing were some of the items permitted, provided you abided by the other requirements noted.
Seems to me like you may be limited by how much gas is in your car, as travel for outdoor activities does not allow for any stopping in between your home and destination, and back. In theory, you could buy gas so you could "go to the grocery store or pharmacy", or for some other approved life sustaining purpose on the way home, but I think that would be in violation of the spirit of the order. Who knows though. We're off the maps here.
The big moral issue I see in choosing to continue to fish right now, provided you follow the above rules, is burning fuel in your vehicle for "non-life sustaining" reasons, and thus needing to potentially create additional exposure for yourself and others by having to purchase fuel more often than you would if you were not fishing. In the grand scheme of things, I'm not sure how significant that is, if you're otherwise doing everything right. Still...If SIP does happen in PA, and you are allowed to fish, or engage in outdoor activities, I'd try to stay local. All three of the vehicles in my household have full (or nearly full) tanks right now. Both my wife and I are working from home and not commuting at the present, so we're not really using any gas, other than a once/week grocery store run...3 miles round trip. (We're going to try and stretch that out some too, within reason. We don't want to panic buy large stocks of anything.) Still, unless things with CV improve and orders are lifted, it will be my plan to burn what's in all three before buying gas again for any reason.
FWIW, I fished for a while this morning. Straight from home to the stream, and back. Did not pass Go, did not collect $200. A small Lancaster County Class A that was my plan was a zoo, relatively speaking. 3 other anglers there by 10:00 AM, spread over maybe a mile or so. I went to a nearby un-stocked, nat repro stream and had that to myself. I burned about an 1/8 of a tank of gas doing it.
Again, PA (if SIP is ordered) may have different rules than CA when it comes to outdoor activities. Everyone should respect, and abide by whatever those rules are. If it means no fishing, it means no fishing.