It is an image as ghostly as it is ghastly: Five California sea lions dangling lifeless in the current, strangled by the net in which they remain ensnared.
The photograph is the work of underwater cinematographer Howard Hall, who presumes that Mexican gill-net fishermen are responsible.
"I'd like to say that I was shocked, but I really wasn't because I've seen this type of thing before -- on both sides of the border," Hall said.
Marty Snyderman, another well-known photographer, was with Hall and helped jump-start a secretive effort to remove the seemingly abandoned net -- with an undetermined number of victims in its mesh. Both men were diving earlier this month at the Lobster Shack, a popular spot off the Coronado Islands, 20 miles southwest of Point Loma in Mexican waters. It's a remote destination on the leeward side of North Island, one of four small islands that make up the group. Divers often are treated to close-up encounters with sea lions, because there is a rookery nearby.
"Obviously, if you're going to drop a net there you're going to catch sea lions," Hall said.
He first came across the net Nov. 6. It was a set-net with anchors, about 150 feet long and 30 feet wide. Four sea lions were wrapped and already had succumbed. Hall returned the next day with Snyderman and diving companion Mark Thurlow. The net had entangled and killed a fifth sea lion. It also had entrapped a soupfin shark, still faintly struggling, and a deep-diving cormorant.
Gill-net fishing is legal in Mexico. The divers say they shot the footage and stills because the scene shows so dramatically how gill nets indiscriminately kill. Snyderman sent his images to the San Diego Oceans Foundation in hopes that the conservation group's contacts in Mexico could do something about the net.
Noelle Barger, executive director of the foundation, said just taking the net might be considered stealing -- and dangerous -- because gill nets usually are tended by fishermen.
"But we made a few calls, and the people we talked to made a few calls, and we heard back a few days later that it was taken care of," Barger said. In 1990, California imposed restrictions requiring that gill nets be at least three miles from coastal waters and one mile from island waters. Hall hopes that publicity generated by his images will draw attention to the fact that even in California waters, this sort of thing happens outside the restricted areas.
The California Department of Fish and Game last year sold 209 general gill-net permits that allow two sizes of mesh. The large mesh nets are used mostly for swordfish and shark. A net with smaller mesh is used for white sea bass, halibut and other small market species.
The National Marine Fisheries Service estimated that 89 sea lions were killed in large-mesh drift gill nets last year from southern Oregon to Mexico. Data from the small-mesh fishery are not available.
The fisheries service also has determined that 6,591 animals per year can be killed without adversely affecting the total population.
Despite the threat of nets, the sea lion population has been growing since the Marine Mammal Protection Act passed in 1972 -- skyrocketing at a rate of 6.2% a year recently.
"Most biologists find it hard to understand why the population hasn't crashed due to disease," Steve Crooke, a DFG biologist, said. "The best guess is that it is larger than before the white man arrived."