ACS Monterey Bay Program for November 2007

From Killer Whales To Kelp Forests

Killer Whale photo by Nancy Black

Thursday, November 29, 2007 7 p.m. Refreshments, 7:30 p.m. Program Lecture Hall, Monterey Boatworks, Hopkins Marine Station, Pacific Grove (Across from American Tin Cannery Outlet Stores) Speaker: Dr. James Estes, Supervisory Zoologist, California Science Center, National Biological Service, Santa Cruz, CA; Adjunct Professor, Biological Sciences, University of California, Santa Cruz; Research Biologist, Institute for Marine Sciences, University of California, Santa Cruz

Dr. Estes is an internationally recognized expert on the coastal ecosystem of Alaska's Aleutian archipelago and, among other critters, the sea otter. Jim has studied this ecosystem since the early 1970's. Because of his many years of collecting data, making observations and publishing of results Jim's work has made ground breaking contributions to what is known about this coastal ecosystem and the linkages it has to other marine habitats.

In the early years, Jim's research team observed killer whales swimming with otters with no apparent interaction. In 1991 an orca was first observed attacking a sea otter and the attacks continued. A 25% decrease in the sea otter population was observed during the first few years of the 1990s.

This shift in the orcas' predation caused a substantial disruption in the coastal ecosystem and Jim's observations were summarized in the October 18, 1998 issue of the UCSC's Currents:

"The new phenomenon of killer whales preying on sea otters appears to be one link in a chain of interactions extending from the open sea to the coastal zone and involving a wide range of species at different levels of the food chain. Over exploitation of certain North Pacific and Bering Sea fisheries may have initiated this cascade of ecological effects."

Ultimately, with the decline in sea otters there was also a decline in the coastal kelp forest.

Recently, Jim was a co-editor of a new book, Whales, Whaling and Ocean Ecosystems, University of California Press, December 2006. One of the ideas discussed in this book is that commercial whaling prompted a dietary shift in killer whales that previously preyed on the large whales. Now smaller marine mammals, including sea otters, are targeted by orca.

Jim's talk will focus on the work done by him and his colleagues over the years on sea otters and kelp forest ecosystems in southwest Alaska with some discussion of the role of large predators in other systems. Various implications of this work for conservation and management will also be included.

Please join us at our monthly meeting to hear the latest from this cutting edge marine scientist, researcher and thinker.

References:
UCSC CURRENTS, Killer whales feed on sea otters, pushing coastal ecosystems off kilter October 19, 1998;
UCSC CURRENTS, Marine ecologist wins Pew Fellowship to support Bering Sea research July 19, 1999;
UCSC CURRENTS, James Estes to receive Ed Ricketts Marine Science Award, present lecture on Saturday, March 10, 2003;
UCSC Press Release: New Book explores the effects on whales and whaling on ocean ecosystems, January 29, 2007.

Related web pages:

• University of California Santa Cruz
• UCSC Press Release: New Book explores the effects on whales and whaling on ocean ecosystems, January 29, 2007.

• Back to list of previous meetings.