What do all you Oceana scientists and fish experts think of this? Here's the full article (which, to give credit where credit is due, I came across on Gristmill).
Blanchard and his friends measured the weight of female reproductive organs -- incongrously, called "gonads" in black rockfish -- the species that prompted Oregon's Labor Day sport closure. They correlated the female gonads' weight to sea surface temperatures. The gonad weights they found in the non-El Nino year of 1996 were the same they found in 1995, when there was a mild El Nino. The mild event had no effect on gonad weight, compared to the normal winds year of 1996.
But in 1997, when a full-fledged El Nino arrived, gonad weights dropped. It was a signal that went unrecognized, but it foretold of fewer groundfish being born that year -- and fewer catch fish in the near future.