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Day 7 - September 23, 2008 - Isla Carmen And Isla Catalina, Baja California Sur, Sea Of Cortés, Mexico

By Bob Rubin and Tony Huntley

Noon position: 16° 50’ 54” N and 99° 54’ 12” W

It was a warm Sea of Cortès morning. We awoke at anchor near Punto Colorado on the southwest side of Isla Carmen, slightly south of the mainland town of Loreto. The entire bay of Loreto including this and several other islands are part of the Loreto National Marine Park. This park was created by presidential decree in 1996. It covers over 2000 square kilometers and in 2005 was listed as a UNESCO World Heritage Site.

After breakfast, we went ashore for snorkeling in this small pristine cove. At least thirty-five species of fishes were seen here, of which nine were endemic to the Sea of Cortès. The most abundant were the scissor-tailed damsels, four different species of parrotfishes and the three most common trigger fishes.

Following our snorkel, we hiked into a dry arroyo adjacent to the landing site. The recent rains had turned the hills from brown to green. The area was a veritable arboretum of species. As we walked through this area, the adaptations for life in a desert environment were clearly obvious. Many plants had small sized leaves (microphylly) typical of desert organisms. Many plants have few or no leaves and rely on green stems for photosynthesis. The abundant and diverse cactuses take this to another level. They have evolved accordion expansion pleats that allow them to “tank up” when water is abundant. We also saw several desert reptiles, including the endemic Carmen Island Desert Iguana. We also saw Blue-footed Boobies, ospreys, Yellow-legged Gulls, and Magnificent Frigatebirds.

As the noon hour approached, the temperature rose to almost 38 °C. Most of us took the opportunity to swim before we returned to the ship for lunch. Following lunch, we arrived at Punto Elefante on Isla Santa Catalina. During our walk on shore we were treated to several unique species. In particular, this island is home to the giant barrel cactus. Unlike the normal variety found in the mainland deserts and elsewhere in the Baja, this plant can reach a diameter of up to 7 feet and a height of more than 14 feet. We explained to the guests that this is an example of “island gigantism,” seen in many species on islands around the world. These cactuses were abundant on the unusually green hillsides along with large numbers of tall cardon cactuses, the smaller chollas and organ pipes. Surprisingly, the washes supported a large number of the endemic Santa Catalina Desert Iguana, whiptail lizards, side-blotched lizards, and spiny lizards. Additionally, this is the home of the only rattle-less rattlesnake in the world. Although it was not seen, this snake is another example of the extreme forces of evolution associated with species isolation islands.

The beaches of these islands show the remnants of the former fishing camps that dotted these islands. All that remains are the scraps of wood and steel from old boats, derelict refrigerators and the odd piece of net or line. Over-fishing and the collapse of the fisheries have taken it toll on this once profitable industry. The inclusion of these islands into the parks system and the pristine nature of the surrounding waters bode well for the future reestablishment of the abundance and diversity once seen here.

Snorkeling in water with approximately 40 feet visibility allowed us to observe Yellow-tailed Tangs, Sergeant Majors, several species of parrotfishes, Scissor-tailed Damsels, Fine Scaled Triggerfish, and our first view of Giant Hawkfish.

As we traveled in the Zodiacs around the point at sunset, we were treated to a multicolored light show as the “vermillion sea” proved true to its name. The ocean took on a deep reddish cast as the cactuses changed from green to red to purple against the darkening sky. Just as it did to John Steinbeck and Ed Ricketts six decades ago, the Sea of Cortés had once again cast its magical spell on another group of curious naturalists.

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