Monterey Bay National Marine Sanctuary

ENDANGERED AND THREATENED SPECIES   MBNMS Home Introduction Sancutary Program Accomplishments Intertidal Systems Rocky Subtidal Systems Open Ocean & Deep Water Systems The Physical Environment Wetlands and Watersheds Endangered & Threatened Species Marine Mammals Bird Populations Marine Mammals & Bird Surveys Harvested Species Human Interactions Further Reading Credits Sea Otters in the Sanctuary A large proportion (72 percent) of the California population of sea otters (Enhydra lutris nereis) is found within the boundaries of the Monterey Bay National Marine Sanctuary. Small populations of otters also exist at San Nicolas and San Miguel Islands off Southern California. For the past ten years, the mainland range has been well-established between Año Nuevo Island at the north end and Purisima Point at the south. Through the years, individual otters have occasionally been seen as far north as Bodega Bay. Within just the last year, otters also for several months occupied Cojo Bay to the south of the established range, in a group often numbering over 100 animals. In 1911, otters were protected under the International Fur Seal Treaty from fur hunting. Additional protection was afforded via the federal Endangered Species Act (ESA), under which the species has been listed as "threatened" since 1977, and by the Marine Mammal Protection Act, where otters are listed as "depleted." With these protections, the population has slowly grown in size and range. However, the population remains small relative to historic levels, and is vulnerable to impacts from oil spills, point- and non-point water pollution, accidental capture in some types of fishing gear, and other human-related activities. Despite the ease with which sea otters can be observed and studied, the individual and collective role each real or potential impact can play remains difficult to isolate and quantify. Reversing what had been a generally slow but positive growth trend, the California otter population began an apparent decline in 1994 that persists in 1998. (See Figure 1.) Sea Otter Survey Data Spring Fall Year Total Pups Total Pups PPI SPR% FAL% %Dead 1982 1346 222 1338 144 292 - - 7.4 1983 1275 122 1226 164 214 -5.3 -8.4 9.2 1984 1304 123 - - - 2.3 - 10.1 1985 1360 236 1221 155 306 4.3 - 5.1 1986 1570 225 1204 113 285 15.4 -1.4 5.1 1987 1650 220 1369 108 267 5.1 13.7 5.6 1988 1724 219 - - - 4.5 - 5.0 1989 1856 285 1599 115 337 7.7 - 5.1 1990 1678 214 1636 120 281 -9.6 2.3 5.7 1991 1941 241 1661 138 309 15.7 1.5 3.9 1992 2101 291 1715 134 344 8.2 3.3 4.9 1993 2239 217 1805 143 288 6.6 5.2 5.5 1994 2359 283 1845 115 343 5.4 2.2 5.3 1995 2377 282 2190 137 331 0.8 18.7 6.6 1996 2278 315 2019 161 385 -4.2 -7.8 7.9 1997 2229 310 2205 197 376 -2.2 -0.7 6.8 1998 2114 159 1937 211 250 -5.2 -12.2 9.3 (PPI Pup Production Index; SPR%C % Change Total Otters, Spring; FALL%C % Change Total Otters, Fall; %DEAD % Dead as Percent of Spring Count) Survey counts can fluctuate from year to year without providing proof that the population is actually declining. However, there has been an overall decline of 11 percent between the Spring 1995 and Spring 1998 counts, a downward trend that has persisted for three years and appears real. If this rate of decline continues, the California sea otter population may qualify for an "endangered" listing under the ESA as early as the year 2000. Hand in hand with the decreased numbers from the surveys, and supporting the sense that the decline is indeed real, has been an increase in the number of dead otters recovered each year since around 1991 (shown in Figure 1 as a proportion of total otters counted the previous spring). Sea Otter Research and Conservation Program In a cooperative project headed by the Marine Wildlife Veterinary Care and Research Center in Santa Cruz and the Wildlife Health Center at the University of California at Davis, with assistance from the U.S. Geological Survey Biological Resources Division and the Monterey Bay Aquarium, thirty otters were captured from Monterey, Moss Landing, and Santa Cruz as part of an ongoing effort to assess the health status of the southern sea otter population. During a short holding period, project participants tagged the animals for identification purposes, and collected blood to monitor baseline hematological parameters and to test for the prevalence of Brucella, Leptospira, canine distemper, calicivirus, and Coccidioides immitis in free-ranging and rehabilitated southern sea otters. Plans are underway by this same group to study behavior and causes of mortality in juvenile southern sea otters, to examine contaminant levels in sea otters and coastal invertebrate species, to monitor accidental drownings of sea otters that become entrapped in gear used for coastal fin-fish fisheries and gillnet fisheries in Monterey Bay, and to reinitiate field studies on basic behavioral and demographic parameters, all in an effort to understand and mitigate the causes of the current southern sea otter population decline better. On another note: at least three boat-strike deaths occurred in Elkhorn Slough in 1998, including an otter successfully raised and reintroduced through the Aquarium's rehabilitation program. Another boat-strike victim, rescued from Monterey harbor, required orthopedic surgery to repair a broken ankle, but was eventually returned to the wild. Andrew B. Johnson Monterey Bay Aquarium, Sea Otter Research and Conservation Program Sources of mortality among otters range from the natural to the unexpected. The unexpected finding of the past few years, from studies by the National Wildlife Health Center, has been that infectious disease accounts for 40 percent of the sea otter deaths, a level five times higher than that typically seen in wild, free-ranging populations of other animals known to or studied by the Center. These diseases are encountered by otters in food or water; there is no known incidence of these diseases being communicable to other otters, other marine animals, or humans. Some of these diseases may have been present in the otter population for decades but gone undetected until recently, when more exacting post-mortem examinations were made. In others cases, the presence of some diseases are apparent on even a gross examination of the dead otter, and changes in infection rates indicate a change within the otter environment or with an otter's physiological and immunological ability to ward off the infection. Increased susceptibility to disease can be caused by the presence of environmental contaminants. Sea otters are exposed to various environmental contaminants through point- and non-point sources and through the nearshore food web, which includes many species of filter-feeding shellfish that concentrate contaminants before they are eaten by otters, seabirds, or humans. Our understanding of the role played by these contaminants is still astoundingly incomplete. Endangered Species Snapshot: Sanctuary Salmon and Steelhead Populations Warm ocean temperatures associated with El Niño harmed southern Coho salmon populations. Adults arriving in the fall and early winter, when the temperatures were highest, were most affected; because of the warm temperatures early females produced eggs with no nucleus. Even in March-April (with cooler water), where 80-90 percent fertility is common, fertility was in the 60-70 percent range. Very high winter and spring river flows destroyed both Coho food (aquatic insects) and their nests. The good news: in the summer the tremendous flows continued, so populations were in better shape, in that regard, than they've been in past drought years. Angling regulations changed significantly in 1998. The San Lorenzo River is now the only river where one can catch and keep steelhead; all others are "catch and release." In that river one can keep hatchery fish only. The Carmel River was opened for "catch and release" of steelhead in winter 1998 for the first time in ten years. Sea lions' fondness for salmon continued to create conflicts between sea lions and fishers. However, this year saw an increased cooperative effort between conservation groups, fishers, and scientists to address this issue. The California Department of Fish and Game allotted significant funds in 1998 to watershed restoration. (These include, by county: Marin - $40,881; San Francisco - $0; San Mateo - $136,684; Santa Cruz - $241,188; Monterey - $117,271; San Luis Obispo - $65,000.*) It also completed a draft restoration plan for Coho salmon in Santa Cruz and San Mateo Counties. * These figures represent funds allocated by the end of the calendar year; additional 1998 funds will be distributed in 1999. Jenny Carless Editor Our knowledge of the role played by nearshore fisheries is also still incomplete. Resource users - particularly those in commercial sea urchin and abalone shellfisheries - are watching closely to see how recent sea otter survey and mortality information affects sea otter population recovery and management decisions, and potentially, the livelihood and survival of key fisheries. Likewise, concerns over possible sea otter entrapment in fish and shellfish traps have grown over the past year, as has renewed awareness of possible continued entanglement in coastal gill nets. A clearer understanding of the impact of fisheries on sea otters, and of otters on fisheries, is critical to guiding future conservation management decisions. Other California coastal resource uses, such as oil extraction and transport, local kelp harvest activities, and human recreational activities, also contribute to possible impacts on otters and their habitat. Sea otters serve as an "indicator" species of ecosystem change, and perhaps more telling, an indication of how well we can use our collective creative intelligence to resolve issues of sea otter and nearshore ecosystem recovery, protection, and future management. The Sanctuary provides not only critical habitat to 70 percent of the population of this species, it will serve a catalytic role in addressing issues related to its health, recovery, and management. Ellen Faurot-Daniels Energy, Ocean Resources, and Technical Services Div., California Coastal Commission Examples of Endangered and Threatened Species of the Monterey Bay National Marine Sanctuary The Sanctuary is home to many endangered and threatened species. The Sanctuary's legislation works in concert with the Endangered Species Act (ESA) and other laws to protect the marine environment. A species is listed as "endangered" if it is in danger of extinction throughout all or a significant portion of its range, or "threatened" if it is likely to become endangered in the foreseeable future. The chart below highlights some of the listed species found in the Sanctuary. Organism Federal Status State Status Cetaceans Blue whale (Balaenoptera musculus) Endangered None Humpback whale (Megaptera novaeangliae) Endangered None Fin whale (Balaenoptera physalus) Endangered None Sperm whale (Physeter macrocephalus) Endangered None Right whale (Eubalaena glacialis) Endangered None Sei whale (Balaenoptera borealis) Endangered None Pinnipeds Guadalupe fur seal (Arctocephalus townsendi) Threatened Threatened Steller sea lion (Eumetopias jubatus) Threatened None Birds California Brown Pelican (Pelecanus occidentalis) Endangered Endangered California Least Tern (Sterna antillarum browni) Endangered Endangered California Snowy Plover (Charadrius alexandrinus nivosus) Species of Special Concern Threatened Marbled Murrelet (Brachyramphus marmoratus) Threatened Endangered Fissiped Southern sea otter (Enhydra lutris) Endangered None Turtles Green sea turtle (Chelonia mydas) Threatened None Leatherback sea turtle (Dermochelys coriacea) Endangered None Pacific ridley sea turtle (Lepidochelys olivacea) Threatened None Loggerhead sea turtle (Caretta caretta) Threatened None Anadromous Fishes Chinook salmon (Oncorhynchus tshawytscha) - spring Canidatae for Endangered Listing Threatened Chinook salmon (Oncorhynchus tshawytscha) - winter Endangered Endangered Coho salmon (Oncorhynchus kisutch) - Central CA Threatened Endangered Steelhead trout (Oncorhynchus mykiss) Threatened None Source: California Dept. of Fish and Game; US Fish and Wildlife Service Compiled by Kip Evans, Monterey Bayt National Marine Sanctuary Right Whale Sighting One of the world's most endangered baleen whales, the right whale, was sighted off the Big Sur coast in early 1998. For marine scientists and whale biologists, this particular event was extraordinary not only because of the rarity of such sightings, but because it was a unique observation of two different types of baleen whales interacting. Sanctuary Superintendent Bill Douros and NOAA pilot Matt Pickett looked down from their plane during aerial surveys and saw a large black whale being chased by several gray whales. Douros estimates that there were twelve gray whales in an area of about a quarter square mile near the right whale, although only two were obviously interacting with the right whale. The fifty-foot right whales were hunted to the brink of extinction near the turn of the century. They are very rare along the California coast. Nineteenth century whaling records show that right whales were once abundant along all major continents in the temperate waters of the northern and southern hemispheres, although their numbers may have been much lower along the Central Coast. In the eastern North Pacific, they could once be seen from central Baja California to the Bering Sea in Alaska. Today, such sightings are few and very scattered. During the past fifteen years, only four verified sightings have been recorded in the eastern North Pacific, yet now three of these were within the boundaries of the Sanctuary. Some experts estimate that as few as fifty to 100 right whales are left in the eastern North Pacific. (Please see Spring 1998 newsletter for further details on this sighting and on right whales.) Kip Evans Monterey Bay National marine Sanctuary

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Last modified on: June 1, 1999