Predator Heads North

As oceans warm, the Humboldt squid of equatorial seas is moving north into new waters

• Hannah Schardt
• Oct 01, 2007

IT SOUNDS like something out of a supermarket tabloid: Massive squid takes over California coast! But the expanding range of the Humboldt, or jumbo, squid is all too real, and now scientists have the data to prove it. Once found mostly in equatorial waters, the squid--named for the Humboldt Current of Peru--is invading the sea off central California.

National Wildlife reported two years ago that the cephalopod, which can weigh up to 100 pounds and reach 7 feet in length, was worrying scientists--and delighting the squid fishing industry--by taking up residence in Mexico's Sea of Cortez. Some researchers feared the squid's appearance meant that other large predators, including tuna, marlin and hammerhead sharks, were suffering from catastrophic overfishing, leaving a gap in the food chain. The highly adaptable squid--it reproduces and reaches sexual maturity far faster than fin fish--filled the gap. Occasionally, individual squids were spotted even farther north, but no one was sure whether they were anomalies or signs of things to come.

Now, in a study published in the Proceedings of the National Academy of Sciences, researchers at Stanford University and the Monterey Bay Aquarium Research Institute have determined that the squid are firmly entrenched in Golden State waters. Based on video evidence and marine census data, they found that large numbers of the squid arrived in central California's Monterey Bay after a mild El Niño event in 2002--and stayed. Scientists now believe that decreased competition and predation by sharks and other top-level predators allowed the squid to gorge virtually unimpeded on the bay's hake and anchovy populations. In fact, commercially valuable hake and anchovy fisheries are already suffering from the squid's voracious appetite, which means that the Humboldt may have to answer to one predator that could try to block its rapid range expansion: Homo sapiens.