Southern California Channel Islands Research Articles

A Decade of Scuba Effort Reevaluates Approach for Surveying White Abalone (Haliotis sorenseni Bartsch, 1940)

Accurate distribution and density data of endangered marine species may be complicated by artifacts from exploitation, survey design, and general difficulty in accessing subtidal habitats. Occasional review of survey data may help restructure survey efforts to improve conservation outcomes. The white abalone (Haliotis sorenseni) is a marine gastropod listed under the Endangered Species Act thought to primarily inhabit depths beyond conventional scientific SCUBA limits (30–60 m) in the southern California Channel Islands. This study reviews surveys at four Channel Islands and four locations along the southern California mainland coast within SCUBA depth ranges and conducts a simulation comparison of the larger survey design used for this study with the standard transect approach presently common in the region. White abalone density was greater along the mainland, particularly in Point Loma and La Jolla, than the Channel Islands, where no live white abalone were recorded. The larger survey approach was found to be more effective at finding simulated white abalone, beyond the expected difference in areal coverage alone. These results show that surveys within SCUBA limits are an effective way to monitor H. sorenseni and that impacts from overfishing on the Channel Islands may make sections of the mainland coast one of the last refuges of white abalone. The greater efficiency of larger surveys can complement standard transect approaches to improve abalone monitoring at sites of interest. Both results can be applied to the immediate conservation of white abalone by improving site selection and monitoring approaches to active restoration efforts.

Moving on up: Vertical distribution shifts in rocky reef fish species during climate-driven decline in dissolved oxygen from 1995 to 2009.

Anthropogenic climate change has resulted in warming temperatures and reduced oxygen concentrations in the global oceans. Much remains unknown on the impacts of reduced oxygen concentrations on the biology and distribution of marine fishes. In the Southern California Channel Islands, visual fish surveys were conducted frequently in a manned submersible at three rocky reefs between 1995 and 2009. This area is characterized by a steep bathymetric gradient, with the surveyed sites Anacapa Passage, Footprint and Piggy Bank corresponding to depths near 50, 150 and 300 m. Poisson models were developed for each fish species observed consistently in this network of rocky reefs to determine the impact of depth and year on fish peak distribution. The interaction of depth and year was significant in 23 fish types, with 19 of the modelled peak distributions shifting to a shallower depth over the surveyed time period. Across the 23 fish types, the peak distribution shoaled at an average rate of 8.7 m of vertical depth per decade. Many of the species included in the study, including California sheephead, copper rockfish and blue rockfish, are targeted by commercial and recreational fisheries. CalCOFI hydrographic samples are used to demonstrate significant declines in dissolved oxygen at stations near the survey sites which are forced by a combination of natural multidecadal oscillations and anthropogenic climate change. This study demonstrates in situ fish depth distribution shifts over a 15‐year period concurrent with oxygen decline. Climate‐driven distribution shifts in response to deoxygenation have important implications for fisheries management, including habitat reduction, habitat compression, novel trophic dynamics and reduced body condition. Continued efforts to predict the formation and severity of hypoxic zones and their impact on fisheries dynamics will be essential to guiding effective placement of protected areas and fisheries regulations.

Distribution, Habitat, and Population Size of Island Night Lizards on San Nicolas Island, California

The Island Night Lizard (Xantusia riversiana) was removed from the federal list of threatened species in May 2014. This strongly differentiated species is endemic to 3 of the southern California Channel Islands—San Clemente, San Nicolas, and Santa Barbara. Suitable habitat for Island Night Lizards is extensive on San Clemente Island, and the species is abundant there. Habitat is limited and fragmented, however, on San Nicolas Island and small Santa Barbara Island. Bringing together extensive field surveys and mark-recapture sampling, we synthesize available data for Island Night Lizards on San Nicolas Island and calculate population and density estimates for the species in major habitats on the island. Island Night Lizards are widely distributed across most of the eastern half of San Nicolas Island. In contrast, they are nearly absent over the western third of the island except for isolated populations in boulder beach habitats. We combined mark-recapture population estimates with comprehensive measurements of the extent of cactus, boxthorn, and other habitat types on the island to arrive at a more accurate assessment of the status of Island Night Lizards on San Nicolas Island. High densities of Island Night Lizards on the island are found in small areas of cholla cactus (Cylindropuntia prolifera; mean of 4100 lizards/ha), boulder beach habitat (mean of 3400 lizards/ha), and prickly pear cactus (Opuntia spp.; mean of 1700 lizards/ha); low numbers are found in more extensive mixed-shrub habitat (mean of 250 lizards/ha). The U.S. Fish and Wildlife Service requires a post-delisting program for “monitoring the overall health of the Island Night Lizard” to assure the continued long-term viability of the species in its restricted distribution. The information on population size and habitat presented here will inform and guide conservation and management efforts by the U.S. Navy on San Nicolas Island over the coming years.

Validation of the names of two new species of Codium (Chlorophyta, Bryopsidales) from Isla Guadalupe and Rocas Alijos, Pacific Mexico and the southern California Channel Islands, with some remarks on insular endemism

Abstract The names Codium schmiederi and Codium dawsonii are validated by the provision of designated types. The species to which the invalidly published name C. schmiederi applies is known only from Isla Guadalupe and Rocas Alijos, Baja California, Mexico. The history of phycological exploration of these two remote localities is detailed. The species to which the invalidly published name C. dawsonii applies is found in those two localities as well as on coastal islands of Baja California and southern California. It is seldom found on the mainland. Codium hubbsii, originally described from Islas San Benito, has a distribution similar to that of C. dawsonii, but occurs more often on the mainland. The distributions of these three species constitute a pattern of insular endemism.

The Dolphin Hunters: A Specialized Prehistoric Maritime Adaptation in the Southern California Channel Islands and Baja California

Synthesis of faunal collections from several archaeological sites on the three southernmost California Channel Islands and one in the Cape Region of Baja California reveals a distinctive maritime adaptation more heavily reliant on the capture of pelagic dolphins than on near-shore pinnipeds. Previous reports from other Southern California coastal sites suggest that dolphin hunting may have occurred there but to a lesser extent. While these findings may represent localized adaptations to special conditions on these islands and the Cape Region, they call for reassessment of the conventionally held concept that pinnipeds were invariably the primary mammalian food resource for coastal peoples. Evidence of the intensive use of small cetaceans is antithetical to the accepted models of maritime optimal foraging which assume that shore-based or near-shore marine mammals (i.e., pinnipeds) would be the highest-ranked prey because they were readily encountered and captured. While methods of dolphin hunting remain archaeologically invisible, several island cultures in which dolphin were intensively exploited by people using primitive watercraft and little or no weaponry are presented as possible analogs to a prehistoric Southern California dolphin-hunting technique. These findings also indicate that dolphin hunting was probably a cooperative endeavor among various members of the prehistoric community.

BARRIERS TO GENE FLOW IN EMBIOTOCA JACKSONI, A MARINE FISH LACKING A PELAGIC LARVAL STAGE

Marine species generally show high dispersal capabilities, which should be accompanied by high levels of gene flow and low speciation rates. However, studies that focused on the relationship between dispersal and gene flow in marine fishes have been inconclusive. This study focuses on the black surfperch, Embiotoca jacksoni, a temperate reef fish that lacks a pelagic larval stage and lives on almost continuous reefs along the California and Baja California coasts. Mitochondrial control-region sequences from 240 individuals were obtained, and phylogeographic patterns were analyzed. A major phylogeographic break was found at Santa Monica Bay, a sandy expanse that prevents adult dispersal. Deep water separating the southern California Channel Islands was also found to be a major barrier to gene flow. Minor phylogeographic breaks were also detected in the Big Sur/Morro Bay and in the Punta Eugenia/Guerrero Negro regions, but none in the Point Conception region. Gene flow levels in E. jacksoni were found to be almost identical to those of another species with limited dispersal, Acanthochromis polyacanthus, thus indicating that the lack of a pelagic larval stage combined with barriers to adult dispersal may have had similar effects on these two species.

A Night-Lighting Technique for At-Sea Capture of Xantus' Murrelets

-We captured 575 Xantus' Murrelets (Synthliboramphus hypoleucus) with spotlights and dip nets at 3 islands in the Southern California Channel Islands during April and May of 1995-1997. Working at night (2100-0500 h), 3-person teams in inflatable boats located murrelets with a spotlight and captured them in dip nets from the waters near known breeding colonies at Santa Barbara, Anacapa, and San Clemente Islands. Our average capture rate was 4.7 murrelets hr'1, but we captured up to 12.3 murrelets hr. We recaptured 34 murrelets or 6% of the capture total. We recommend this simple, inexpensive, safe and effective night-lighting capture technique for Xantus' Murrelets and other seabirds. Received 7 March 1997, accepted 26 May 1997, final version received 26 September 1997.

California Sea Lion Distribution: A Statistical Analysis of Aerial Transect Data

Sightings of California sea lions (Zalophus californianus) recorded on 23 aerial transect surveys of the Southern California Bight were pooled by 30' x 30' grid cells. Contour maps generated from celldensity estimates were used to represent seasonal distributions. The mean number of animals at sea in 3 seasons was calculated by summing cell population estimates, and the jackknife technique was used to place confidence limits on the at-sea component of the summer breeding population. California sea lions concentrate near their rookery islands and at specific open-water locations in summer. The center of their distribution shifts to the northwest in autumn and to the southeast in winter and spring, probably in response to prey availability. J. WILDL. MANAGE. 51(1):13-20 The California sea lion population in California is large and growing. Most breeding occurs on the southern California Channel Islands, where counts of pups show that the population doubled every 10 years since 1950 (Bonnell et al. 1984). Some of this growth may have resulted from immigration because counts of California sea lions at the 2 largest Mexican rookeries (Islas San Benito and Cedros) declined 40% between 1976 and 1981 (comparison of Jun counts) (Mate 1977, LeBoeuf et al. 1983). As of 1982, California sea lions on their southern California rookery islands totalled >50,000 animals (Heath and Francis 1983, Bonnell et al. 1984, Stewart and Yochem 1984). As the population in California has grown, California sea lions have been increasingly associated with fisheries conflicts, prompting an assessment of this species' status (see Demaster et al. [1982] for a review). Most knowledge of California sea lions is derived from studies of populations on land. Until recently, little was known about their habitat utilization and distribution at sea. Beginning in 1975, study was undertaken to map the distributi n at sea of all marine mammal species, including California sea lions, found in the Southern California Bight (SCB). Data were collected on 23 aerial surveys conducted over a 3-year period; each survey required about 20 hours in the air (Bonnell et al. 1980). From 1975 to 1978, 30,996 km (17,047 nautical miles) of trackline were flown. Our paper examines the pattern of California sea lion distribution in the SCB and places confidence limits on density values and population size estimates. Data were collected as part of the BLM-OCS Survey Program, supported by contracts between the U.S. Bur. Land Manage., U.S. Dep. Interior, and the Univ. California, Santa Cruz. The development of the distributional model was supported by a contract to WoodwardClyde Consultants (WCC), Walnut Creek, Calif., from the U.S. Minerals Manage. Serv. We are grateful to the many individuals involved in the collection of these data: D. H. Dettman, G. D. Farrens, C. B. Heath, B. J. LeBoeuf, and M. O. Pierson. We thank T. P. Winfield and R. This content downloaded from 207.46.13.111 on Tue, 09 Aug 2016 06:17:17 UTC All use subject to http://about.jstor.org/terms 14 SEA LION DISTRIBUTION * Bonnell and Ford J. Wildl. Manage. 51(1):1987 121

An evaluation of uranium-series dating of fossil echinoids from southern California Pleistocene marine terraces

Fossil sea urchins ( Strongylocentrotus) from Pleistocene marine terraces on the southern California Channel Islands have been dated by the uranium-series method in order to test the suitability of echinoids for dating marine terraces. Results indicate that urchin plates and spines do not behave as closed systems with respect to both uranium and thorium. Calculated ages based on these data do not agree with uranium-series ages (120,000 and 127,000 yrs) obtained previously from corals from the same localities. Thus, fossil sea urchins ( Strongylocentrotus) are not considered suitable for uraniumseries dating of Pleistocene marine terrace deposits.

Northern Elephant Seals and California Sea Lions: New Hosts for Cattle Egrets

The colonization and range expansion of the Cattle Egret (Bubulcus ibis) along the Pacific coast of the United States during the last two decades is well documented (Cogswell, H. L., Water birds of California, Univ. of California Press, Berkeley, 1977). The species has established several breeding colonies in California, including one at the Salton Sea where several thousand birds now breed annually (L. Jones, pers. comm.). Since the late 1970's, egrets have also been regular winter visitors on the southern California Channel Islands (L. Jones, pers. comm.). We report here on interactions observed between foraging Cattle Egrets and northern elephant seals (Mirounga angustirostris) and California sea lions (Zalophus californianus) on San Nicolas Island, California. We observed five immature Cattle Egrets on San Nicolas Island on 10 days between 5 December 1980 and 25 January 1981, while conducting research on the pinnipeds. Egrets spent most of each day foraging near breeding northern elephant seals on two beaches at the extreme southwestern end of the island. The egrets moved among small groups of breeding elephant seals, striking at kelp flies (Fucellia costalis, possibly other species, especially Coelopa vanduzeei), which densely covered some of the larger seals. They gleaned flies from adult and subadult males more often than they did from juveniles or females, perhaps because the bulls were more tolerant of them and also were more densely covered with flies. Flies were widely distributed over the seals' bodies, but were heavily concentrated around anal and penile openings, eyes and mouth, and especially wounds. An egret would stalk flies for a short period, wagging its head from side to side, and then remove them with a quick jab. The egrets also fed on flies on the sand and kelp between the seals in the same manner, and on various insects in the coastal vegetation, which is dominated by iceplant (Gasoul sp.). They generally foraged singly when gleaning flies from seals but in groups when in the iceplant. Although sea lions also occurred on these beaches, we did not see birds glean flies from them during this period. On 12 days between mid-January and early May we also observed immature Cattle Egrets feeding from and among elephant seals and sea lions on several other beaches. On 4 April, for example, we saw an egret perched on a dead sea lion removing flies from the carcass. On 8 and 9 May, another egret spent several hours gleaning flies from the carcasses of sea lion pups. Adult and immature Western Gulls (Larus occidentalis), which had been feeding on the dead pups earlier, were displaced by egrets, and would approach no closer than 1 to 2 m while an egret was near the carcasses; they did, however, resume feeding on the carrion once the egret departed. Occasionally, gulls attempted to approach carcasses on which egrets were foraging. When this happened, the egret would become alert, straighten its neck, and look around without moving from its perch. This posture was generally sufficient to cause gulls to retreat with their heads tucked in California sea lions were present during this period on several beaches where egrets and northern elephant seals occurred, but we saw an egret removing flies from a live sea lion only once (9 May). Sea lions may be less tolerant to gleaning attempts by egrets. The Cattle Egret's opportunistic foraging behavior and use of food sources avoided by other herons, as illustrated by our observations, is probably an important factor in its success in colonizing the New World and expanding its range in the Old World. We thank Judy Newman and Pamela Yochem for sharing their observations with us and J. R. Jehl, Jr., J. Diamond, D. Power, W. T. Everett, H. L. Jones, G. McCaskie, L. C. Binford, and J. C. Ogden for reviewing the manuscript.

Certain Crescentic Stone Objects as a Time Marker in the Western United States

AbstractA class of pressure-flaked stone objects of crescentic shape made to an easily recognizable pattern is usually associated with surface sites adjacent to continuous or discontinuous bodies of water or playas. The crescent has a distribution from the Southern California Channel Islands to western Utah and the Columbia Basin in Washington. Even though its function is not yet known, it nevertheless is — because of a unique and consistent association of attributes — a useful material culture trait that may serve as a marker for a particular cultural complex. The trait is not known to be associated with the small-game hunting and food-gathering based cultures of the Archaic stage. Archaeological evidence indicates that the crescent is contemporaneous with big-game hunting cultures of the techno-economic level associated with the upper Lithic stage.

The Weights of Chipped Stone Points: A Clue to Their Functions

The Weights of Chipped Stone Points: A Clue to Their Functions