Moved from Fishing Spiders.

This appears to be Dolomedes vittatus. Distinguishing these guys from Dolomedes scriptus males can be rather tricky at times, so here's a couple physical characteristics that I use to tell the two apart:

1.) Generally, the abdomenal markings of adult male D. scriptus have a more "sculptured" appearance, whereas D. vittatus have less-pronounced markings.
2.) The two dark-colored spots in the middle of the cephalothorax are almost always more robust in D. vittatus than the more narrow ones found on D. scriptus.

Here's some images from the Guide that might help clarify some of this:

Dolomedes vittatus


Dolomedes scriptus


Hope that helped a little...