Dive Dry with Dr. Bill

011: San Miguel Island

A week before Labor Day I received e-mail from one of my dive buddies, Danielle, who is a Dutch biologist and president of the UCSB SCUBA Club. She asked if I'd join her on a dive trip to San Miguel and Santa Rosa Islands. I've never dived these more remote islands and since one of my goals is to dive all eight of our Channel Islands, it took no additional persuasion. I packed my dive gear and drove up to Santa Barbara where we stayed on board the Truth Aquatics dive boat Conception the night before our dives.

The few times I have been out to San Miguel, the weather has been atypical: warm and full of sunshine instead of the frequent fog that forms due to the cold waters there. San Miguel is influenced by the cold California Current sweeping down from central California. Our first dive site was offshore Wilson Rock. A giant stride off the boat and I was immediately reminded of the two quarter-sized holes in my 7mm wetsuit! The bottom temperature was a mere 50 degrees.

I was struck by the contrast between this site and what I'm used to here on Catalina... and I'm not just referring to the water temperature. There was no giant kelp to be seen, only a few sea palms. Looking around the reason was fairly clear. There were abundant sea urchins right out in the open on top of the rocks... not hiding in crevices as they do on Catalina. This site was an urchin barren and any kelp had been eaten. On Catalina urchins would not venture out like this in daylight... the sheephead would quickly make urchin caviar out of them. However, I only saw two sheephead the whole time I dove San Miguel.

Other fish common on Catalina but absent in these sites were the garibaldi, blacksmith, kelp bass, halfmoon and opaleye. All have been recorded north of San Miguel, but none were present at our three dive sites. Instead there were a number of cold water species we don't normally see at SCUBA depths on Catalina. These included the blue rockfish, lingcod and painted greenling which were all fairly common. These species are also recorded south of Catalina, but are generally not seen in the shallower and warmer waters of our island. We were also surprised by a large school of tubesnout that appeared without warning.

In addition to the abundant sea urchins, other members of the spiny skinned echinoderms were very common. These included ochre starfish and bat stars, both present on Catalina, and sunflower starfish which are known as far south as Baja but generally in the deeper, colder waters. The sunflower stars with their 15-24 arms were quite impressive. These large starfish are highly predatory, feeding on other starfish and sea urchins. They had plenty of food at all three sites we dove.

Nudibranchs were also much more common than in our Dive Park, and many different species were represented. These shell-less snails are often the highlight for many divers and biologists. Their bright colors were a treat to videotape as they feasted on sea anemones and hydroids.

Whales of several different species are often reported near the northern Channel Islands. As we dove, it became very apparent why such large mammals would be present in these waters. As I was filming, the rock surface I had focused on was quickly obliterated by a brownish cloud. Taking my eye from the viewfinder I discovered the cloud was a large school of krill, small shrimp-like crustaceans that serve as the primary food source for many whale species. These schools were thick as the proverbial pea soup (and had much more protein).

We dove two more sites, Harris Point and Lover's Cove, and found ecologically similar habitats at each site. After only three dives it was time to reboard the Conception for Santa Barbara. Unfortunately there wasn't time to dive Santa Rosa as well, but the dives on San Miguel were definitely worth the trip. It was good to compare how different the marine life can be a mere 100 miles away from Catalina, and this trip reminded me of the value of diving other locations. Of course I prefer diving the tropics, and plan to spend a good part of the winter in warmer waters!

© 2003 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.

Image caption: Sunflower star with its many arms; lingcod- a favorite of hunters;
sea urchin barren with bat star; cloud of krill

This document maintained by Dr. Bill Bushing.
Material © 2003 Star Thrower Educational Multimedia