For large baleen whales, the approach of a vessel once meant great danger, and those that knew better dived for the depths. Today, the threat of the harpoon is gone in most waters, yet whales must still contend with the vessels themselves. Prop-powered, steel-hulled and ever in a hurry to meet the demands of the global economy, open-ocean ships travel faster and in greater abundance today than they ever have before, and collisions between vessels and water mammals are on the rise. In virtually all cases, the animals lose.

This accelerating trend has been starkly obvious along California's busy coastline, where an alarming number of dead humpback and blue whales have washed ashore in recent months with injuries almost certainly caused by bows and propellers. High underwater noise poses an issue of concern, too, and while there is no easy way to monitor the doings of ships far from shore, in Marin County one small nonprofit organization—Seaflow, based in Sausalito's Fort Cronkhite—demands that within our coastal state and federal marine sanctuaries, large ships put on the brakes for whales.

Founded in 1999, Seaflow aims to protect whales, dolphins and porpoises from the negative effects of boats and their noise. This March, the organization launches its Vessel Watch Project, a volunteer watchdog effort to monitor ships as they enter and leave San Francisco Bay. Seaflow plans to charter small fishing vessels and take volunteers out the Golden Gate to both observe passing ships and to take readings of underwater sounds and their volumes and frequencies with subsurface microphones. Sentinels may also be stationed on the Marin Headlands with binoculars and cell phones.

"We want to involve the public while educating and informing them, as well as the policy makers," says Seaflow executive director Robert Ovetz. "By bringing out citizens and getting them involved—letting them hear what the underwater soundscape is like, see how fast these vessels are going and how they're treating our marine sanctuaries like superhighways—we think that'll have a tremendous impact on the progress we make."

According to a 2006 paper published by Mark McDonald, John Hildebrand and Sean Wiggins with the University of California, the ocean's global fleet of commercial vessels more than doubled from 41,865 in 1965 to 89,899 in 2003. In the same 38-year period, the gross tonnage of ships grew from 160 million to 605 million. Port turnaround has grown more rapid, too, meaning that each of these ships spends more time than before on the water. An increase of about 10 decibels in the 30 Hz to 50 Hz frequency range at a recording site near San Nicolas Island off of Santa Barbara correlates with this fleet growth, and many scientists believe that such noise disturbs and possibly injures marine mammals like whales.

In fact, underwater measurements with microphones at the same spot have detected what appears to be a shift in the vocalization strategy of blue and fin whales. Megan McKenna, a graduate student at the Scripps Institution of Oceanography and a scientific correspondent for Seaflow, says that the animals' calls have increased by about seven decibels from 80 to 87 in the past 40 years, an increase of five times the intensity (it's a logarithmic scale).

The increase in volume closely resembles the increase in general ambient ocean noise, most of which comes from ships, and McKenna suggests that the whales may be vocalizing more loudly to make themselves better heard and understood by their peers amidst the din of boat noise. "It begs the question," he says. "Is there a threshold where whales can no longer hear each other through this background noise?"

Sound carries with great ease under water. In the "deep sound channel," a layer of water characterized by a particular range of pressure and temperature parameters and which hovers as much as a thousand meters below the surface, noise may carry literally across oceans.

"Mankind has made the ocean a very noisy place, and most of it is due to commerce," says Toby Garfield, a professor of oceanography at San Francisco State University. "The biggest change the ocean has seen has been with the development of the diesel engine and fast freighters."

According to Ovetz, ocean noise has approximately doubled every decade for the past 40 years. Observations are inconclusive, but many scientists believe that low frequency vibrations generated by ships can deafen and disorient marine mammals as well as drive them from their breeding and feeding areas. The noise may also lead indirectly to the flustered whales being struck by the ships.

Such occasions have historically been rare. Between Los Angeles and the Point Reyes Peninsula from 1986 to 2004, only 12 whales are known to have been hit by ships.

But between September and October of 2007, three blue whales and two humpbacks were found dead on Southern California beaches with cracked skulls and other injuries plainly suggestive of violent interactions with big metal objects. Another humpback was found in similar condition at Point Reyes this fall.

The abrupt increase in ship-whale collisions cannot be ignored, says Ovetz. "This is a record number of highly endangered species being killed by shipping traffic," he charges.

Research by Woods Hole Oceanographic Institution has found that when a ship reduces its speed from 20 knots to 10 knots, it also reduces the risk of collision with whales by 40 to 50 percent. The National Oceanographic and Atmospheric Association has proposed implementing a speed limit outside Boston Harbor and other ports, but the suggestion has been opposed by the World Shipping Council, which argues that such impediments to ship travel would cost captains and maritime companies money.

Currently, the Channel Islands National Marine Sanctuary (NMS) imposes a voluntary speed limit of 10 knots, but whether any vessels follow the suggestion is not clear. Seaflow holds the opinion that a required 10 knot speed limit in local waters would protect marine mammals while generating other benefits.

"Reducing the speed limit to 10 knots in the sanctuaries would not only lessen the risk to whales, but save fuel for the ships and reduce emissions into the air," Ovetz says. "It's a win-win-win situation."

According to Matt Zolnierek, lieutenant with the Coast Guard's Vessel Traffic Service, a strict code of rules regulates the bay's boat traffic, which includes approximately 400 daily "transits," many of which are roundtrips by ferries or fishing vessels. Radar surveillance ensures that boats obey a speed limit of 15 knots. Outside the Golden Gate, however, vessels are largely free to act and move about as they wish, says Zolnierek. The only safety rule is one of traffic lane separation, which the Coast Guard monitors as inbound and outbound ships maneuver past one another near the Golden Gate Bridge.

Ninety percent of all imported goods arrive in the United States by ship, and every day 10 large vessels come streaming through the Golden Gate, according to stats from the San Francisco Marine Exchange. Unavoidably, these vessels plow right through the Farallones and the Monterey NMS, which, like other areas established by the Sanctuaries Act of 1972, is designed to protect resources and marine life. Ovetz believes it is the federal government's obligation to assure that within such zones—as well as state-monitored Marine Protected Areas—ships do not create a hazard for wildlife, either by striking animals directly or blasting them with their tremendous volumes of low frequency noise.

Seaflow's Vessel Watch Project has received a boost of interest and support following the November Cosco Busan oil spill. Plans to begin a watchdog program of local boat traffic are accelerating, and the calendar has been marked with five tentative cruise dates on which chartered vessels will motor volunteers out the Gate to conduct vessel-watching activities. Using underwater microphones, cables and headphones, volunteers will listen to the endless subsurface rumblings with which whales must contend. Seaflow will also measure the speed of passing ships and consider what hazards such boat traffic may present to marine mammals.

Also on Seaflow's agenda is construction of a database of the large vessels that regularly visit San Francisco Bay. Coast Guard records, says Ovetz, will reveal which boats have been involved in local accidents or have violated traffic codes. Vessel Watch observations will then discover whether any such ships repeat their offenses and whether authorities respond with a crack of the whip or just a slap of the hand. Large cargo vessels regularly enter the bay carrying over a million gallons of tarlike bunker fuel, and these boats cannot be allowed to put the public and the public's resources at risk, Ovetz says.

"Sanctuaries have a responsibility to protect natural resources within their boundaries. That's not always being done out here, and someone needs to call them on it. With the Vessel Watch program, we will be the eyes and the ears of the ocean."

For more information on Seaflow, visit [ http://www.seaflow.org ]www.seaflow.org.

Send a letter to the editor about this story.