NATURAL PERSPECTIVES:

Last week, the Amigos de Bolsa Chica hosted a town hall meeting at the Wetlands and Wildlife Care Center at Newland and Pacific Coast Highway. Attended by an overflow crowd, the mini-symposium covered the two years of changes that have occurred in the water, plants, fish and birds at Bolsa Chica since the opening of the ocean inlet in August 2006. Vic was the moderator. I sat in the audience and took notes, an easier task.

Some of the many interesting things we heard at the meeting were about sharks, stingrays and guitarfish. Christopher Lowe of Cal State Long Beach reported there are about 1,500 stings per year from stingrays in the United States. Seal Beach gets the lion’s share of those encounters, with 200 to 400 stings noted per year, mostly from June through August. The worst place is right at the mouth of the San Gabriel River, where the water is the warmest. When swimmers accidentally step on them, the stingrays whip their tails up, stinging hapless swimmers on their feet and ankles.

Lowe’s mark and recapture studies of tagged stingrays indicate there are about 16,000 stingrays hanging just off the coast at Seal Beach. No wonder so many people get stung. However, any individual ray generally only stays there for one to three days. Then it takes off. Turns out that one of the places where they may be going is the newly restored full tidal basin at Bolsa Chica. The attraction of this new bay may pull some of the summer stingrays from Seal Beach, lessening the impact of swimmers being stung.

Lowe’s graduate student, Thomas Farrugia, spoke about the studies he conducted with another of Lowe’s graduate students, Mario Espinoza, a Fulbright Scholar from Costa Rica. They tracked movements of shovelnose guitarfish, leopard sharks and gray smoothhound sharks at Bolsa Chica. These bottom-dwelling elasmobranchs (cartilaginous fishes) are the top underwater predators at the Bolsa Chica. Farrugia and Espinoza were pleased to find a wide range of sizes of these fish at Bolsa Chica, which suggests the bay may be serving as a nursery for small shark species.

By tagging these fish and tracking them with acoustic telemetry, Farrugia and Espinoza discovered where they roam in the bay. Gray smoothhound sharks are more active than guitarfish, moving about the bay more. Guitarfish tended to stay in smaller areas. But how they discovered this was nearly as interesting as the findings themselves. After seining the bay for sharks and guitarfish, they attached an acoustic emitter that broadcasts sound in a range that is inaudible to fish. Then these poor graduate students had to motor around the bay in a boat, taking GPS readings every 10 minutes for 24 hours to create a tracking map of the movements of the fish. Ah yes, we remember having to do 24-hour time points back in our graduate school days. There must be a law somewhere that says graduate students have to stay up all night in order to gather data for their theses.

Fish weren’t the only things discussed at this meeting. Birds got their fair share of coverage as well. As anticipated, birds love the new full tidal basin. Terns and plovers have taken to the new sandy nesting areas like, well, like ducks to water. Rachel Woodfield of Merkel and Associates said an average of 8,000 birds a day use the full tidal basin at Bolsa Chica, with Western sandpipers being the most abundant species. Overall, shorebirds are the major users of the new inlet and associated mudflats, but upland birds, ducks, and aerial predators such as terns and pelicans are also abundant.

The bird species monitored most closely were Western snowy plovers and California least terns, which are threatened and endangered, respectively. Both species nest at Bolsa Chica.

In 2008, preliminary data indicate between 42 and 147 plover chicks fledged out of 193 eggs laid. That seems like a huge range, but remember the chicks hatch at different times and run around like crazy when they aren’t hiding, which they’re experts at with their cryptic plumage. Further analysis should refine that data range. Either way, the 2008 season was an improvement over the 25 chicks that fledged in 2007, out of 143 eggs.

The improvement in nesting success seems to be due to the use of metal cages, called exclosures, which are put over snowy plover nests. This keeps out predators such as coyotes and great blue herons, as well as the thousands of terns that nest nearby.

The least tern story was also good this year. In 2007, there were 226 nests at Bolsa Chica, but only 15 chicks fledged. In 2008, there were 242 nests and far more fledged birds. Overall, the least tern population is growing thanks to the use of fencing, volunteer monitors, and predator control. The population has grown from 1,000 nesting pairs in only a few places in California in the early 1980s to about 7,000 now. Bolsa Chica is only one of the places where least terns and snowy plovers nest. In late August, Vic and I attended what we fondly call the Least Tern Barbecue, where volunteers who have been guarding the least tern colony at Huntington State Beach get together for a potluck at the end of nesting season. State parks biologist David Pryor reported that this year they had a whopping 454 least tern nests, the third best year ever. They can always use more volunteers to sit at the beach at Huntington State Beach near the mouth of the Santa Ana River during the morning and early afternoon.

If you’re interested in volunteering next summer, or even now for surveying wintering snowy plovers, e-mail Cheryl Eggers at dc.egger@verizon.net.

VIC LEIPZIG and LOU MURRAY are Huntington Beach residents and environmentalists. They can be reached at vicleipzig@aol.com. VIC LEIPZIG and LOU MURRAY are Huntington Beach residents and environmentalists. They can be reached at vicleipzig@aol.com.