There are three main components to the monitoring effort in Monterey Harbor. First, in September 2002 UCSC undergraduate divers conducted a completely randomized survey of all floating docks in the harbor. The divers searched all sides of the floating docks and the pier pilings that supported them. Based on the results of this survey, several “hot spots” were noted, which became the focal points of subsequent efforts.

Second, volunteer divers recruited by the City of Monterey and under the direction of Dr. Steve Lonhart targeted Undaria hot spots for manual removal. Divers searched the floating docks and along the entire column of the cement pier pilings, removing all Undaria encountered.

And third, SIMoN staff measured and observed the following for all of the removed Undaria: 1) total length; 2) damage; 3) reproductive status (e.g., no sporophylls, sporophylls present but spores not released, and spores released); and 4) location.



This is a collaborative effort that involves MBNMS staff, the California Department of Fish and Game, University of California and California State University researchers and students, and the City of Monterey Harbor Office and Volunteer Program.

A survey of 85 percent of the harbor in September 2003 indicated that Undaria had spread further within the harbor. Although most of the individuals removed at this time were spent adults, and heavily grazed, we also noted the appearance of new recruits. As an annual alga, Undaria typically recruits in the winter, then dies back in summer. However this pattern has changed in Monterey Harbor, where it now appears that the alga recruits almost year-round.

In January 2007, sweeps of the harbor have captured some recruits, few juveniles, and a handful of adults. It is not clear if this is a result of increased managemetn efforts, or part of the system response to the anomalous oceanic conditions in both 2005 and 2006, when upwelling was late and weak.

Scuba divers and dockside volunteers are needed for future monitoring and eradication. For more information on volunteering with the monitoring program, please email Steve.Lonhart@noaa.gov or call 831/420-3661.

• The density and distribution of Undaria pinnatifida within Monterey Harbor varies each year. In some years, recruitment is high, while in others it is low or late. A predictable seasonal pattern is not apparent.
• In 2002, new recruits did not appear until late November. In 2003 new recruits were already apparent in October, and in some areas even earlier. In the fall/winter of 2006, recruits were low in number.
• Sporophylls are usually not apparent until the thallus reaches at least 25 cm. Large individuals (>50 cm) are usually heavily grazed. The herbivorous kelp crab Pugettia producta is common in the harbor, and juveniles are often the thallus of removed Undaria.
• By February 2005, when Undaria should be recruiting in large numbers, fewer than 100 individuals were found and removed from Tiers A through K (the majority of the harbor). In contrast, a small part of D-tier had over 250 individuals removed in February 2004. It is not clear what caused the large decline.