Research Technical Report

Observations of Seabirds, Marine Mammals, Sea Turtle, and Surface-active Fishes in the Vicinity of the Davidson Seamount

MacKnight, R., E. Burton, and A. DeVogelaere (August 2011)

MBNMS Technical Report, 12pp.

SUMMARY

The Davidson Seamount is an inactive undersea volcanic mountain, located approximately 80 miles southwest of the Monterey Peninsula (Fig. 1). Trending northeast-southwest, the Davidson is 26 miles long, 8 miles wide and has a complex morphology; it is composed of about 6 linear ridges, with a large cone structure at the southwest end (Davis et al. 2002, MBNMS 2009, SIMoN 2011). The seamount rises 7,480 feet off the seafloor, though its peak is still 4,101 feet below the sea surface.

This massive seamount, located in an otherwise relatively flat seafloor, may affect circulation patterns of the California Current and California Undercurrent by creating a transient Taylor Column or influencing meandering patterns near the seamount (Rizk 2006). Marine life, including rare deep-sea sponges, corals, and fishes flourish in this environment (DeVogelaere et al. 2005, Burton and Lundsten 2008). Above the seamount, marine mammals, seabirds, and surface-active fishes also thrive.

This is a remote area that can take many hours to reach by boat in often rough seas; thus, relatively few scientific studies have been conducted to document the fauna that utilize the Davidson Seamount habitat. However, fishermen take advantage of the riches the seamount provides, and dedicated birders and marine mammal enthusiasts visit this region to see animals that are rare in Monterey Bay. The following is a summary of the marine mammal, seabird, sea turtle, and surface-active fish observations made by some of the scientists, fishermen, and guides who have been to the Davidson Seamount area. Despite the variety of data collection methods, these observations are valuable for developing a natural history of this remote, yet ecologically-significant marine environment.