How long does pickled herring last?

I just made a few jars of pickled herring, but am leaving town for a month. Will it still be good when I'm back?

I used this recipe:
http://honest-food.net/2011/03/08/swedish-pickled-herring/

Thanks!

I had pickled herring for 7 years and was still good when I opened it. It was canned after pickled.

I heard that they found some pickled herring inside the Great Pyramid of Giza and it was still good...

Thanks, and one more question:

Is botulism a concern with pickled fish? I haven't done the pressure cooking technique to seal the jars. Just brined and soaked in vinegar concoction.

the last line on the recipe says 1 month I would go with that

I will say I ate some pickled eggs, (non-refrigerated, non-canned) that had been sitting for seven months and I am still here.

About 5 minutes.