To develop a baseline of information, we conducted visual strip transects using the submersible Delta, to survey fishes and macroinvertebrates in selected deep, rocky continental shelf and slope habitats of the sanctuary in order to characterize and monitor benthic macrofauna and associated habitats. We also conducted opportunistic dives at locations of special interest to the sanctuary to characterize and locate potential future monitoring sites, including a shipwreck. During September 2003 and August 2004, we completed 79 submersible dives at depths ranging from 60 and 350 meters off the Monterey peninsula and Point Sur, in Soquel, Carmel and Partington canyons, and on the Montebello, a sunken oil tanker off Cambria.

We measured changes in fish species composition, size composition, and relative abundance among the different areas surveyed and also over time when comparing our data to similar data collected in 1993 and 1996. We used 82 transects off the Monterey Peninsula for a power analysis to estimate the number of transects that would be needed in the future to detect various levels of change in the mean density of fish at different confidence levels.

In 2004 we revisited sites off Monterey Peninsula that were surveyed in 1993 and we compared abundance, species-habitat relationships, and species and size composition of benthic fishes. We observed relatively similar species composition. However, except for yellowtail rockfish (Sebastes flavidus) and squarespot rockfish (Sebastes hopkinsi), mean lengths of all rockfishes were greater in 2004 than in 1993.

We completed 14 submersible dives in three submarine canyons to characterize groundfish assemblages associated with the canyons. The main purposes of these dives was to assess the importance of small-scale refugia to species of benthic rockfishes in Soquel canyon in Monterey Bay; to compare fish assemblage among four depths (75, 150, 250 and 350 meters) in Partington Canyon. Additionally, we used the submersible dives in Partington canyon to search for evidence of sediment transfer in the canyon and groundtruth a seafloor habitat map, which was produced with side scan sonar during summer 2003. We conducted two dives in Carmel Canyon to establish a baseline and to explore other potential monitoring sites.

We completed eight dives on the Montebello, an oil tanker that was torpedoed by a Japanese submarine during World War II off Cambria, CA (December 23, 1941). The objective of these dives included: site reconnaissance for the potential threat posed by this oil tanker adjacent to the sanctuary; characterizing the archeological remains of the Montebello; and characterizing the fish and invertebrate fauna. The data collected during the 2003 dives were compared to data recorded during submersible dives conducted at the Montebello in 1996 to assess biological changes and hull degradation.

• Rockfishes were dominant at all locations. Three small rockfish species (Sebastes wilsoni, S. hopkinsi, and S. semicinctus) accounted for more than half of the fish abundance at each location. The large numbers of small rockfishes may be an important forage items for larger fishes as we saw numerous predation events on these small species.
  
  Evidence of regime change: in 2004, we may have observed two northern species, Puget Sound rockfish (Sebastes emphaeus) and redstripe rockfish (Sebastes proriger) rare to this area. Relative to the 1993 surveys, we saw increased numbers of small lingcod, and bocaccio and canary rockfishes which may be attributed to the colder water and recruitment success that has been reported in the last five years for those species.
  
  
• Large groundfish species were more abundant and larger off Point Sur than off the Monterey Peninsula, except for lingcod (Ophiodon elongatus), which was more abundant at an outer ledge area off the Monterey Peninsula.
  
  
• The large rockfish species were larger and more numerous in 2004 than in 1993, whereas the dwarf rockfish species were more abundant in 1993. This may reflect the more stringent fishery regulations that were implemented in the late 1990s.
  
  
• The wreck of the Montebello is an artificial reef that is teeming with fishes and invertebrates, but fishing nets entangled on the wreck are still catching fish.

The submersible dives provided valuable ground-truthing for existing multibeam and sidescan sonar images. Most of the features on the multibeam maps were accurately positioned but occasionally features shown as hard bottom on interpreted maps were covered with sediment. Low-relief, rocky habitats were occasionally difficult to identify on the current multibeam maps of the Point Pinos and Point Sur areas.

Pending future funding, we will be able to identify long-term trends in species composition, size composition, and relative abundance of groundfish in selected areas of the sanctuary. We can then evaluate their recovery rates in areas that were historically abundant but are now depleted, and compare those with population trends of species in similar habitats that are currently abundant.