El Niño refers to a warming of Pacific Ocean waters near the Equator, disrupting global weather patterns and ocean circulations. In the past, the effects of the warming waters were first noted off the coasts of Peru and Ecuador around Christmas, hence the Spanish name El Niño in reference to the Christ child.
The warm water displaced the normally nutrient-rich coastal waters, resulting in a collapse of the anchovy fishery.
What is bad news to some is good news to others. The influx of warm water anticipated along the West Coast of the United States was expected to bring an abundance of exotic sea life not normally seen in in California waters, and it delivered! Yellowfin tuna, dorado, short-billed spearfish, wahoo and blue marlin were among the species caught far beyond their normal range during the summer of 1983. It's that past experience that has anglers eagerly anticipating the next push from the tropics.
After a double-dip La Niña (cooler-than-normal waters) ending this past spring, we're due for a warm episode, right? Well, projections from the specialized ENSO (El Niño Southern Oscillation) models show a clear trend through the end of the year.
We are currently in the process of transitioning into a warm-water period with the Equatorial eastern Pacific sea surface temperature (SST) anomaly of 0.0, otherwise known as neutral conditions. SSTs off the coast of California and Baja California have actually been slightly cooler than normal through mid-July, but they are warming up there as well. Based on the trend shown in the above figure, we will likely see a true, albeit weak El Niño (+.45°C above normal) this coming fall and winter.
An active start to the Pacific hurricane season off the coast of mainland Mexico is another indicator of the presence of warm ocean water nearby. It's often believed by many that storms down below will “push” warm water farther north, closer to California and the West Coast.
While it is true that large storms may have a small impact on the strength and direction of ocean currents, it's not enough to counteract the prevailing large-scale currents along the West Coast. Warming will make its way north due to larger-scale changes in currents and seasonal influence.
That's all good and fine, but how will that affect our fishing? First, it's important to note that these measurements and projections are for the zone along the Equator and not specifically for the West Coast of the United States. However, many times those conditions will have far-reaching impacts on our coastal water temperatures.
Warm-water-loving yellowfin tuna and dorado have already made their way to within range of the one to 1.5-day boats from San Diego. As the water continues to warm and with a clear path for the fish to follow, look for those fish to close in on the one-day range.
As for albacore, the cold-water tuna will head to Northern California, Oregon and Washington. The longfins have shown very little sign of making Southern California offshore banks a part of their seasonal migration route again in 2012. Warming waters won't change that.