Reef Check News


Reef Check Spotlight: Pacific Seahorses Invade Southern California


2016-04-26

By Reef Check California's Southern California Training Coordinator, Katie Kozma
Pictures taken in La Jolla Canyon by local San Diego Diver, Roger Uzun


The Pacific seahorse, Hippocampus ingens, is currently listed as a vulnerable species by the International Union for the Conservation of Nature's (IUCN) Red List of Threatened Species and with a size of about 12 inches, it is one of the largest seahorse species you will find around the world.

This subtropical fish comes in a variety of different colors including gray, brown, red and yellow, which often match the color of the surrounding habitat that they live in. They can normally be found in shallow beds of soft corals and gorgonians in the Eastern Pacific region and they're unique in the fact that they're the only seahorse species that can be found along the California Coast, reaching San Diego Bay. Its normal range extends southward to Peru.

There's a very large demand for dried seahorses in Asia and other places around the world because they have been used as medicine for thousands of years. Each year, tons of Pacific seahorses are caught, dried and shipped to these countries. As the population on the planet increases, the demand for seahorses grows and the number of this species continues to decline, making them a rare sight to be seen even throughout their normal distribution range.

With the influx of unusually warm water that's been brought in by this year's El Niño event, local divers have been seeing some very rare species while diving in Southern California, including the Pacific seahorse. They have recently been spotted in San Diego and as far north as the waters of Alamitos Bay in Los Angeles County, which is the farthest north this particular species has ever been sighted before.

Seeing seahorses in California is definitely unusual, but there are two reasons why an El Niño event could bring them into the waters of Southern California. First, the increased water temperature associated with El Niño could allow them to temporarily expand their range further north. Second, water from the western Pacific is brought towards the American coastline due to the reversal of the Walker cell, a phenomenon that occurs during an El Niño event. This process could potentially transport a seahorse attached to some seaweed drifting in the open ocean into California waters. With this recent increase in Pacific seahorse sightings in Southern California, we may get the chance to see one during the upcoming survey season this year!