The photo does suggest a fine crack in the gel coat but a crack like this may have resulted from an impact that has caused more significant damage to the structural fabrics beneath it. Gel coat is a polyester material that looks nice and presents a smooth surface but really contributes little, if anything, to the overall strength of the layup. Whether you try to repair the gel coat crack or not is really a question of cosmetics. Doing so will not make the boat stronger.
Frankly, I would leave the gel coat crack alone as I think any repair you do at this point will be far more noticeable than the crack itself. If you have reason to believe that water is getting under the gel coat and causing it to delaminate from the hull you could repair it later. But I have canoes that have had cracks in the gel coat since the early 1990s that have not gotten any worse.
What I would do is take a look inside the cockpit at the area beneath the gel coat crack if you have not already done so. Use a headlamp. If you can’t get your head far enough in to see well, use a mirror. Assuming the deck fabric to be Kevlar, check for damage immediately beneath the gel coat crack. Aramid fibers have great tensile strength that usually exceeds the strength of their bond to the resin. So aramid fibers often do not fracture, but simply disassociate from the resin matrix when severely stressed by an impact. This will show up as a white line that corresponds to the fibers that have broken out of the resin matrix.
If you see evidence of internal damage and you feel that the damaged area has more give than the deck on the opposite side, I would simply apply a patch of 5 ounce/square yard Kevlar (or some other aramid fabric) to the underside of the deck with epoxy. This is not difficult to do but if you don’t have the materials or feel inclined to do this, I would look around in your area for someone who does.