I first saw it diving along the far short of the lake. But then it caught a bluegill and swam around holding it for a few minutes before bringing it across the lake towards me. I think that the fish was a bit large for the otter to swallow easily. The otter climbed out of the water onto a log, and appeared to push the fish against the log in order to force it down. The last two pictures are the first two in the time sequence (I put the best photo first).

How to ID P filiformis vs P virginiana without flowers:

This is a patch of P filiformis hiding among P virginiana. Fortunately even without flowers, you can tell the two species apart from these features.

LEAF MARKING:
-P filiformis has a dark chevron that stays on the leaves after they have matured. This dark chevron extends almost all the way to the edge of the leaf
-P virginiana leaves often have a fainter blotchy chevron marking while they are younger, but this chevron fades as the leaves mature. The chevron does NOT extend to the edge of the leaf; it’s confined to the middle ~50% of the leaf.

LEAF SHAPE:
-P filiformis leaves are widest at the middle of the leaf or above (elliptic to obovate)
-P virginiana leaves are widest at or below the middle of the leaf (ovate)

HAIRS ON STEMS:
-Both species have long hairs on the ochrea (papery sheath around the stem where the leaf attaches), but only P. filiformis has long spreading hairs on the stems between nodes.

Bonus: P. filiformis leaves tend to be a lighter shade of green and hairier on the top surface than P. virginiana, but those details are really only easily seen if comparing the two side-by-side.