Tog Fillets

We have been harvesting a fair share of tog on the east end this season. I have noticed that on a few of the fillets, at the top of the fillet where the dorsal fin would be, I have been seeing black lines in the meat. When I try to cut it out, it's deep into the meat. What is this & is it a problem. Anyone else see this?
John

live bait all that is the tog are eating alot of black mussels,, i didnt see any on my tog fillets this season,,, if anyone sees it different chime in,, john nothing wrong with it,,, years back i thought the fillets were no good iv seen the black lines all threw the fillet,,,you cant cut the lines out,, iv eaten those fillets and im still here 🙂 ,, have a good nite,,, ><))):>
><))):>

live bait all that is the tog are eating alot of black mussels,, i didnt see any on my tog fillets this season,,, if anyone sees it different chime in,, john nothing wrong with it,,, years back i thought the fillets were no good iv seen the black lines all threw the fillet,,,you cant cut the lines out,, iv eaten those fillets and im still here 🙂 ,, have a good nite,,, ><))):>
><))):>

Glad you’re still here also.🙂