The boundaries of the Monterey Bay National Marine Sanctuary encompass a high diversity of marine habitats and nutrient-rich waters. These conditions combine to create an area with an incredible level of biodiversity. The populations of some species -- such as krill and jellies -- are thriving in sanctuary waters. However, other species are considered to be "at risk" because their population
sizes are reduced or declining.
Reduced or declining populations may be caused by human exploitation, habitat degradation, disease, environmental change, or a combination of these factors. The sanctuary, through its research, education, and resource management programs, has the ability to help improve the status of many at-risk species. However, to make these efforts most effective, it must determine which species are at risk and which actions will be the most beneficial for each species.
The goal of a new one-year research project of the Sanctuary Integrated Monitoring Network (SIMoN) is to compile this type of information. The project has three phases. In the first, a list was compiled of all the species occurring in sanctuary waters that are designated at risk by a variety of resource management agencies and conservation groups. For the second phase, status reports for a number of species are being generated that cover a variety of topics, including geographic range, abundance, migration patterns, threats, current research projects, and conservation efforts. In the third phase, we will determine what actions the sanctuary can take to help improve the status of at-risk species. Recommended actions may include research projects to collect data needed to improve species management or outreach programs to help increase public awareness of at-risk populations. All the material compiled for this project will be available after the project ends in July 2005 in a published technical report and in digital form on the SIMoN web site.
Below are examples of at-risk species in the sanctuary, with
brief updates on their current status.
 |
| The leatherback turtle is a common summer/fall visitor to sanctuary waters. |
The leatherback turtle, Dermochelys coriacea is a common
summer/fall visitor to sanctuary waters, where it feeds on seasonally abundant jellies. Drastic population declines have led to this species being listed as "endangered" under the federal Endangered Species Act (ESA) and "critically endangered" by the World Conservation Union (IUCN). Human impacts, such as entanglement in fishing gear, ingestion of marine debris, and harvesting of nesting females and eggs, are the main cause of decline. Improving management and conservation of the leatherbacks that visit the sanctuary requires an understanding of when and why they visit these waters as well as where they go and what threats they may encounter after leaving the sanctuary.
The leatherback population in Monterey Bay has been the focus of a research project led by the National Marine Fisheries Service Sea Turtle Research Program. Some of the project’s goals are
to determine foraging areas, habitat needs, and migratory patterns
of this population. Aerial surveys in September found that the
distribution of leatherbacks had shifted this year: fewer turtles were seen in Monterey Bay, and more were seen in areas to the north. Preliminary results suggest that this northward shift may have
been tied to unusual oceanographic conditions in the bay. Satellite transmitters were attached to three leatherbacks in Monterey
Bay in September. Tracking the turtles’ movements will help researchers identify important foraging areas in the sanctuary as well as determine where the turtles go after they leave sanctuary waters.
The Marbled Murrelet, Brachyramphys marmoratus is a small seabird found along the coast between central California and the Aleutian Islands. It has the unusual habit -- for seabirds -- of nesting in old-growth forests. Loss of nesting habitat has caused Marbled Murrelet populations to decline in many areas, with the most dramatic declines in Washington, Oregon, and California (the "three-state area"). For example, in California, murrelets have declined from an estimated 60,000 individuals prior to the start of timber harvesting to a current estimate of 4,600. The southernmost population, which nests in the mountains of Santa Cruz and San Mateo Counties and forages in sanctuary waters, is estimated to contain only 600 individuals.
Given these drastic declines and the three-state area’s geographic isolation from the species’ population center in Alaska, murrelets
in this area were listed in 1992 as "threatened" under the ESA. Listing has increased protections for this species and restrictions on timber harvest near nesting colonies. In May 2004 the U.S. Fish and Wildlife Service (FWS) completed a review of the "threatened" status of the Marbled Murrelet in the three-state area and concluded that this population (which constitutes less than 2.5 percent of the entire species) does not qualify for listing under the ESA as a distinct population segment. However, before the Marbled Murrelet can be reclassified or delisted in the three-state area, the FWS will need to complete a review of the range-wide status of the species. Some researchers and conservationists are concerned that delisting would diminish protection of old-growth nesting habitat and lead to further population declines.
The blue whale, Balaenoptera musculus and humpback whale, Megaptera novaeangliae can been seen year-round in the sanctuary but are most abundant in the summer and fall. Though both species are locally abundant at times, their numbers are still recovering from severe overexploitation by commercial whaling in the early- to mid-1900s. Both are listed as "endangered" under the ESA
and as "depleted" under the Marine Mammal Protection Act. In addition, they are protected from commercial take by the Inter-national Whaling Commission. Even with these protections,
humpback and blue whales still face threats in their environment, including collisions with ships and noise pollution. To help reduce threats in sanctuary waters, whale behavior, abundance, and movement patterns in and around the sanctuary must be better understood.
A collaborative research program, which includes scientists
from a number of Monterey Bay research institutions, is collecting this type of data on humpback and blue whales in and around the
sanctuary. The researchers use ship-board surveys to determine the distribution and abundance of whales in Monterey Bay. This year’s surveys revealed a few unusual patterns for humpback whales, including the early arrival (in May) of many individuals and their spending a higher proportion of time in shallow water (where they were seen feeding on schools of fish). To monitor the whales’ feeding behavior and movement patterns, a total of thirty-three long-term and ten short-term tags were attached to blue and humpback whales off southern and central California in August and September. These tags will allow researchers to determine what the whales are doing while in sanctuary waters and where they go once they leave. Another notable event during this year’s research was the deployment in May of a passive acoustic array in Monterey Bay. By recording visiting whales’ vocalizations, this array allows researchers to determine when different whale species appear in the bay.
Jennifer Brown
Sanctuary Integrated Monitoring Network (SIMoN)
|
