Central North Pacific Ocean Research Articles

Subtropical Cyclogenesis over the Central North Pacific*

Abstract The occurrence of subtropical cyclones over the central North Pacific Ocean has a significant impact on Hawaii’s weather and climate. In this study, 70 upper-level lows that formed during the period 1980–2002 are documented. In each case the low became cut off from the polar westerlies south of 30°N over the central Pacific, during the Hawaiian cool season (October–April). The objectives of this research are to document the interannual variability in the occurrence of upper-level lows, to chart the locations of their genesis and their tracks, and to investigate the physical mechanisms important in associated surface development. Significant interannual variability in the occurrence of upper-level lows was found, with evidence suggesting the influence of strong El Niño–Southern Oscillation events on the frequency of subtropical cyclogenesis in this region. Of the 70 upper-level lows, 43 were accompanied by surface cyclogenesis and classified as kona lows. Kona low formation is concentrated to the west-northwest of Hawaii, especially during October and November, whereas lows without surface development are concentrated in the area to the east-northeast of Hawaii. Kona low genesis shifts eastward through the cool season, favoring the area to the east-northeast of Hawaii during February and March, consistent with a shift in the climatological position of the trough aloft during the cool season. Consistent with earlier studies, surface deepening is well correlated with positive vorticity advection by the thermal wind. Static stability and advection of low-level moisture are less well correlated to surface deepening. These results suggest that kona low formation, to first order, is a baroclinic instability that originates in the midlatitudes, and that convection and latent-heat release play a secondary role in surface cyclogenesis.

Extra-tropical cyclonic/anticyclonic activity in North-Eastern Pacific and air temperature extremes in Western North America

Synoptic extra-tropical cyclone and anticyclone trajectories have been constructed from mean daily sea level pressure (SLP) data using a new automated scheme. Frequency, intensity and trajectory characteristics of these transients have been summarized to form indices describing wintertime cyclonic and anticyclonic activity over the North-Eastern Pacific (east of 170°W) during 1950–2001. During this period, the strength of anticyclones gradually diminished and their frequency became more variable, while cyclones intensified in a discrete shift with deeper lows and further southerly trajectories occurring since the mid-1970s. These changes in synoptic transients translate into anomalously low seasonal mean SLP in the Aleutian Low, a low-level circulation anomaly consistent with the positive phase of the North Pacific Decadal Oscillation, with positive sea surface temperature (SST) anomalies along the west coast of North America and negative in the central North Pacific Ocean. A link between cyclonic/anticyclonic activity and tropical SST anomalies also exists, but this link only becomes significant after the mid-1970s, a period that coincides with more southerly cyclone trajectories. Southward excursions of mid-latitude cyclones during El Nino/positive NPO winters accomplish the northward advection of tropical air and discourage the southward penetration of polar air masses associated with transient anticyclones. Naturally, these changes in cyclonic/anticyclonic activity directly impact surface air temperatures, especially at night. We document these profound impacts on observed wintertime minimum temperatures over Western North America.

Shifting covariability of North American summer monsoon precipitation with antecedent winter precipitation

Previous research has suggested that a general inverse relation exists between winter precipitation in the southwestern United States (US) and summer monsoon precipitation. In addition, it has been suggested that this inverse relation between winter precipitation and the magnitude of the southwestern US monsoon breaks down under certain climatic conditions that override the regional winter/monsoon precipitation relations. Results from this new study indicate that the winter/monsoon precipitation relations do not break down, but rather shift location through time. The strength of winter/monsoon precipitation relations, as indexed by 20-year moving correlations between winter precipitation and monsoon precipitation, decreased in Arizona after about 1970, but increased in New Mexico. The changes in these correlations appear to be related to an eastward shift in the location of monsoon precipitation in the southwestern US. This eastward shift in monsoon precipitation and the changes in correlations with winter precipitation also appear to be related to an eastward shift in July/August atmospheric circulation over the southwestern US that resulted in increased monsoon precipitation in New Mexico. Results also indicate that decreases in sea-surface temperatures (SSTs) in the central North Pacific Ocean also may be associated with the changes in correlations between winter and monsoon precipitation. Copyright © 2006 Royal Meteorological Society.

Differing controls over the Cenozoic Pb and Nd isotope evolution of deepwater in the central North Pacific Ocean

Dissolved Pb and Nd isotope ratios of seawater, as recorded by chemical marine precipitates such as hydrogenetic ferromanganese crusts, have been used as paleoenvironmental proxy tracers. For the North Pacific, however, all ferromanganese crusts studied so far have either been subject to phosphatization or hydrothermal influence in their old part, or only the young parts have been analyzed. Thus, the Pb and Nd isotope compositions of North Pacific deep waters prior to ∼20 Ma are not well constrained. We present new results for three ferromanganese crusts, one of which (CJ01) shows no phosphatization and is located far away from the EPR. Its age is inferred to be ∼75 Ma and thus provides for the first time an opportunity to trace the Nd and Pb isotope evolution of central North Pacific seawater back to the latest Cretaceous.The three crusts, no matter whether phosphatized or not, display very similar Pb and Nd isotope trends with age, suggesting no modification of the Pb and Nd isotope distribution by post-depositional phosphatization. Our data suggest that dissolved Pb in deep waters of the central North Pacific over the Cenozoic and latest Cretaceous has mainly been derived from eolian dust and only to a minor extent from weathering of island arcs. For Pb these trends broadly resemble the Pb isotope evolution of the eolian silicate dust fraction of core LL44-GPC3 in the central North Pacific. We suggest that the isotope evolution of dissolved Pb in central North Pacific seawater has been mainly controlled by Pb released from eolian dust from North America prior to 50 Ma and after 40 Ma from Asia. In contrast, the Nd isotope time series of the crusts are by no means similar to the Nd isotope evolution of the silicate dust fraction in core GPC3, suggesting a decoupling from the Pb and negligible contributions from dust to the dissolved Nd in the central North Pacific deep water. The rise of Nd isotope ratios of Pacific seawater during the Cenozoic has most likely been caused by the increasing volcanic activity and erosion of the volcanic arcs around the Pacific.

Immunohistochemical localization of CYP1A, vitellogenin and Zona radiata proteins in the liver of swordfish ( Xiphias gladius L.) taken from the Mediterranean Sea, South Atlantic, South Western Indian and Central North Pacific Oceans

Cytochrome P4501A (CYP1A) monoxygenase, vitellogenin (Vtg) and Zona radiata proteins (Zrp) are frequently used as biomarkers of fish exposure to organic contaminants. In this work, swordfish liver sections obtained from the Mediterranean Sea, the South African coasts (South Atlantic and South Western Indian Oceans) and the Central North Pacific Ocean were immunostained with antisera against CYP1A, Zrp, and Vtg. CYP1A induction was found in hepatocytes, epithelium of the biliary ductus and the endothelium of large blood vessels of fish from the Mediterranean Sea and South African waters, but not from the Pacific Ocean. Zrp and Vtg were immunolocalized in hepatocytes of male swordfish from the Mediterranean Sea and from South African waters. Plasma Dot-Blot analysis, performed in Mediterranean and Pacific specimens, revealed the presence of Zrp and Vtg in males from Mediterranean but not from Pacific. These results confirm previous findings about the potential exposure of Mediterranean swordfish to endocrine, disrupting chemicals and raise questions concerning the possible presence of xenobiotic contaminants off the Southern coasts of South Africa in both the South Atlantic and South Western Indian Oceans.

The 1997–1999 abrupt change of the upper ocean temperature in the north central Pacific

The abrupt warming of the north central Pacific Ocean from 1997 to 1999 is studied using an ocean data assimilation product. During this period, the average mixed‐layer temperature in the region of 170–210°E, 25–40°N rises by 1.8 K. The major contributors to the warming are surface heat flux (1.3 K), geostrophic advection (0.7 K), and entrainment (0.7 K). For the geostrophic advection, the contributions by the zonal, meridional, and vertical components are 0.4, −0.1 and 0.3 K, respectively. Mixing and meridional Ekman advection have cooling effect. The significance of the geostrophic advection indicates the importance of ocean dynamics in controlling the abrupt warming tendency during the 1997–99 period and the inadequacy of a slab mixed‐layer model in simulating such warming tendency.

On the seasonal and interannual migrations of the transition zone chlorophyll front

High‐resolution satellite measurements of ocean color and surface winds, along with historical in situ data, are used to explore interannual variability in the annual migration of the transition zone chlorophyll front (TZCF) in the central North Pacific Ocean. Significant variations in frontal position and annual range were observed, including a significant southerly displacement during El Niño events. This displacement, apparently forced by enhanced surface convergence and vertical mixing in the transition zone, creates vast regions of anomalously high wintertime surface chlorophyll in the North Pacific Subtropical Gyre. A remarkably close correspondence between the positions of the TZCF and the 18°C surface isotherm over a portion of the central North Pacific allows historical temperature data to be used as a proxy for TZCF position. This surface temperature proxy has revealed decadal‐scale variability in frontal position, with greater (lesser) annual range and southerly extent following the large‐scale 1976–77 (1998–99) climate shifts. Interannual variations in TZCF position could have important implications for the distribution and survival of a number of apex predators that utilize the TZCF as a migratory and foraging habitat.

Forage and migration habitat of loggerhead (Caretta caretta) and olive ridley (Lepidochelys olivacea) sea turtles in the central North Pacific Ocean

AbstractSatellite telemetry from 26 loggerhead (Caretta caretta) and 10 olive ridley (Lepidochelys olivacea) sea turtles captured and released from pelagic longline fishing gear provided information on the turtles’ position and movement in the central North Pacific. These data together with environmental data from satellite remote sensing are used to describe the oceanic habitat used by these turtles. The results indicate that loggerheads travel westward, move seasonally north and south primarily through the region 28–40°N, and occupy sea surface temperatures (SST) of 15–25°C. Their dive depth distribution indicated that they spend 40% of their time at the surface and 90% of their time at depths <40 m. Loggerheads are found in association with fronts, eddies, and geostrophic currents. Specifically, the Transition Zone Chlorophyll Front (TZCF) and the southern edge of the Kuroshio Extension Current (KEC) appear to be important forage and migration habitats for loggerheads. In contrast, olive ridleys were found primarily south of loggerhead habitat in the region 8–31°N latitude, occupying warmer water with SSTs of 23–28°C. They have a deeper dive pattern than loggerheads, spending only 20% of their time at the surface and 60% shallower than 40 m. However, the three olive ridleys identified from genetics to be of western Pacific origin spent some time associated with major ocean currents, specifically the southern edge of the KEC, the North Equatorial Current (NEC), and the Equatorial Counter Current (ECC). These habitats were not used by any olive ridleys of eastern Pacific origin suggesting that olive ridleys from different populations may occupy different oceanic habitats.

Low activity and seasonal change in population size structure of grenadiers in the oligotrophic abyssal central North Pacific Ocean

Analysis of video recordings of swimming in abyssal grenadiersCoryphaenoidesspp. revealed site differences in tail‐beat frequencies. At the highly oligotrophic deep central North Pacific (CNP; 5800 m depth) station fishes had significantly lower tail‐beat frequencies (0·73 ± 0·02 Hz, mean ± s.e.) than fishes of similar size at the shallower ‘Station F’ (Sta. F; 4400 m depth) beneath the more productive waters of the California Current Upwelling (1·06 ± 0·04 Hz). These behavioural differences may be evidence for the proposed physiological adaptations ofCoryphaenoides armatusandCoryphaenoides yaquinae, to different depths and food supply levels. At CNP, smaller fishes (38·9 cm meanLT) were present in autumn than in summer (59·4 cmLT) suggesting large‐scale migrations across the abyssal ocean floor despite the observed slow swimming speeds.

A 370-ka paleoceanographic record from the Hess Rise, central North Pacific Ocean, and an indistinct ‘Kuroshio Extension’

A 5 m long core (NP36) collected from the Hess Rise in the central North Pacific Ocean (34°11.7′N, 179°15.4′E, water depth 2664 m) was analyzed for benthic and planktonic foraminifera. This core yields a continuous record for the last ca. 370 000 years according to the oxygen isotope stratigraphy. Cross-spectral analysis of down-core variations in planktonic δ18O values correlates well with the SPECMAP reference scale allowing recognition of marine isotope stages (MIS) down to MIS 10 and the δ18O variations coincide well with the changes in sea surface temperature derived using the modern analogue technique. Time-series analyses of mass accumulation rates (MAR) of planktonic and benthic foraminifera were also performed along with analysis of variations in faunal composition. MAR of planktonic foraminifera display maxima during glacial periods which, together with coincident changes in lightness (L*) of sediment measured with the spectrophotometer, strongly suggests increasing flux of eolian dust to the Hess Rise due to strengthened westerly winds. However, MAR of benthic foraminifera including Epistominella exigua, a common typical phytodetritus feeder, also display highest increases during some interglacial periods (i.e. MIS 5 and 7). The benthic MAR maxima are thought to reflect variations in consumption patterns between benthic and planktonic species. A proposed hypothesis that vigorous grazing of phytoplanktons occurred during glacial periods reducing the flux of phytodetritus to the sea floor in turn impacting and limiting production of benthic foraminifera with the opposite effect prevailing during interglacial periods. Down-core variations in right-coiling Neogloboquadrina pachyderma abundance and the composition of planktonic foraminiferal faunas indicate the Subarctic Front did not shift southward over the study site during the past 370 000 years. Alternatively, variations in faunal composition indicate that Subtropical Water prevailed in the study area throughout this period. No clear faunal evidence of the presence of the ‘Kuroshio Extension’ was found in core NP36 reflecting the loss of heat and tropical faunal elements from this water mass as it flowed eastward during late Quaternary climatic maxima and minima.

Seasonal variations in planktonic foraminifera at three sediment traps in the Subarctic, Transition and Subtropical zones of the central North Pacific Ocean

The distribution and flux of planktonic foraminifera in the North Pacific Ocean were studied for a 1 year period beginning in July 1993 using time-series samples collected in three sediment traps deployed in a north–south transect along 175°E longitude. Sediment trap locations allowed monitoring of faunas within the Subarctic, Transition and Subtropical water masses in this region. Seasonally high foraminiferal flux rates were recorded at the Subarctic site during periods of intense stratification of surface water accompanied by high fluxes of organic matter and biogenic opal contents. Faunal composition dominated by sinistral forms of Neogloboquadrina pachyderma and Globigerina umbilicata at the latter site characterized the Subarctic water mass feature. Data collected at the Transitional and Subtropical sites illustrate differences in seasonal flux rates and in relation to those recorded at the Subarctic site. Faunal composition at the Transitional water mass site was dominated by dextral phenotypes of N. pachyderma, whereas this taxon was absent at the Subtropical site. Also, during the period of warmest surface temperature (October), Globigerinoides ruber became dominant at the Transitional water mass site in contrast to the Subtropical water mass site where Globigerinoides sacculifer became dominant while associated with common occurrences of Globigerinoides tenellus and Globorotalia tumida. Much lower fluxes of planktonic foraminifera, organic matter and biogenic opal also marked Subtropical water. The distinctive differences in faunal composition and flux rates at the Transitional and Subtropical sites suggest that little if any exchange of surface water occurred between these two sites and, in particular, in the area representing the distal Kuroshio Extension.

Wind-Forced Intraseasonal Sea Level Variability of the Extratropical Oceans

Seven years' worth of sea level observations from the TOPEX/Poseidon altimeters and wind observations from the European Remote-Sensing Satellites (ERS-1/2) scatterometers were used to investigate the dynamics of large-scale intraseasonal sea level variability at mid- and high latitudes. Coherent patterns of sea level variability with spatial scales of 1000 km and timescales of 20 days to 1 year are identified in three particular regions: the Bellingshausen Basin west of Drake Passage, the Australian–Antarctic Basin, and the central North Pacific Ocean (30°–50°N) near the date line. Significant coherence is found between wind stress curl and the sea level variability. A simple barotropic vorticity equation, in which the time rate of relative vorticity variation is balanced by the wind stress curl and a damping term, is used to simulate the sea level anomalies with a significant degree of correlation with the observations. Although the coherence between the simulation and the observation is significant from periods of 30 days to 1 yr, the variance of the simulation is too low at periods shorter than 100 days. This is probably caused by the errors in the wind forcing as well as the other terms neglected in the vorticity equation. The simulation requires a damping timescale generally longer than 20 days, consistent with theoretical estimates of the dissipation timescales of a frictional bottom boundary layer. In the Bellingshausen Basin, the phase of the coherence between sea level and wind stress curl also shows dependence on frequency according to the dissipation mechanism and estimated damping timescales. However, the results at the other two locations are less conclusive.

Biogeochemical Significance of Adenosine Triphosphate Measurements for Estimating the Carbon Biomass of Bacteria in the Central and Eastern North Pacific Ocean during Summer

Biogeochemical Significance of Adenosine Triphosphate Measurements for Estimating the Carbon Biomass of Bacteria in the Central and Eastern North Pacific Ocean during Summer

Upside-Down Swimming Behavior in a Whipnose Anglerfish (Teleostei: Ceratioidei: Gigantactinidae)

Three individuals of a whipnose anglerfish, Gigantactis sp., were observed near the bottom in the North Central Pacific Ocean. An image from one of three videotape sequences discussed herein represents the first photograph of live behavior in members of the fish family Gigantactinidae. Foraging and escape behaviors included drifting and swimming upside-down. Close association with the bottom while drifting suggests foraging on benthic organisms. Escape behaviors also indicate a lack of stamina consistent with a sit-and-wait bathypelagic predator.

Ichthyolith strontium isotope stratigraphy of a Neogene red clay sequence: calibrating eolian dust accumulation rates in the central North Pacific

Cenozoic pelagic (‘red’) clays of predominantly eolian and hydrogenous origin blanket much of the central North Pacific ocean basin. The eolian component is a key indicator of past paleoclimatic conditions; thus, Cenozoic atmospheric circulation can potentially be reconstructed through provenance studies of Pacific red clays, provided there are precise age controls. Methods commonly employed in the past to date red clay cores have included cobalt accumulation rates, ichthyolith biostratigraphy, magnetostratigraphy, and ichthyolith strontium isotope stratigraphy. The first two dating methods yield ages with large uncertainties, while magnetostratigraphy is only relevant to cores with accumulation rates in excess of 1 mm/kyr. Ichthyolith strontium isotope stratigraphy has shown promise as a chronological tool in marine studies, but has been only sparingly employed in the dating of marine red clay sequences. In this study, we present a complete age–depth profile for a large diameter piston core from the central North Pacific Ocean (EW9709 PC-01, 32.5°N, 141.2°W), consisting of 11 m of primarily wind-deposited dust. To generate this age–depth profile, strontium isotopic compositions were determined on fish teeth ichthyoliths previously cleaned of contaminants using a newly modified reductive cleaning procedure. Ages were determined by reference to the recently refined Sr isotope curve for Neogene seawater. Comparison with nearby giant piston core LL44-GPC3 reinforces the accuracy of our methods. The data for EW9709 PC-01 indicate a fairly constant sediment accumulation rate of ∼0.45 mm/kyr over most of the 24 Myr time period represented by this core.

A new record of a second seagrass species from the Hawaiian archipelago: Halophila decipiens Ostenfeld

Halophila decipiens Ostenfeld, a new record for the Hawaiian Islands, was collected from three locations spanning the archipelago: Midway Atoll at 3–15 m deep, O’ahu Island at 1–2 m deep, and Hawai’i Island at 40 m deep. These findings expand the biogeographical distribution of this pantropical seagrass into the north central Pacific Ocean. Specimens showed morphological, reproductive and DNA characteristics typical of the species.

Cenozoic evolution of Asian climate and sources of Pacific seawater Pb and Nd derived from eolian dust of sediment core LL44‐GPC3

The large‐diameter piston core LL44‐GPC3 from the central North Pacific Ocean records continuous sedimentation of eolian dust since the Late Cretaceous. Two intervals resolved by Nd and Pb isotopic data relate to dust coming from America (prior to ∼40 Ma) and dust coming from Asia (since ∼40 Ma). The Intertropical Convergence Zone (ITCZ) separates these depositional regimes today and may have been at a paleolatitude of ∼23°N prior to 40 Ma. Such a northerly location of the ITCZ is consistent with sluggish atmospheric circulation and warm climate for the Northern Hemisphere of the early to middle Eocene. Since ∼40 Ma, correlations between Nd (−7.55 > εNd(t) > −10.81) and Pb (18.625 < 206/4Pb < 18.879; 15.624 < 207/4Pb < 15.666; 38.611 < 208/4Pb < 38.960; 0.8294 < 207/6Pb < 0.8389; 2.0539 < 208/6Pb < 2.0743) isotopes reflect the progressive drying of central Asia triggered by the westward retreat of the paleo‐Tethys. Comparisons between the changes with time in the isotopically well‐defined dust flux and Nd and Pb isotopic compositions of Pacific deep water allow one to draw two major conclusions: (1) dust‐bound Nd became a resolvable contribution to Pacific seawater only after the one order of magnitude increase in dust flux starting at ∼3.5 Ma. Therefore eolian Nd was unimportant for Pacific seawater Nd prior to 3.5 Ma. (2) The lack of a response of Pacific deep water Pb to this huge flux increase suggests that dust‐bound Pb has never been important. Instead, mobile Pb associated with island arc volcanic exhalatives probably consists of a significant contribution to Pacific deep water Pb and possibly to seawater elsewhere far away from landmasses.

Larval anisakid nematodes from four species of squid (Cephalopoda: Teuthoidea) from the central and western North Pacific Ocean

Third-stage larvae of two species of the genus Anisakis, A. simplex (Rudolphi, 1809) and A. physeteris Baylis, 1923, and those of two types of Lappetascaris sp. are described from four species of squids from the central and western North Pacific Ocean. Larvae of Lappetascaris sp. Type A were 15-33 mm long and occurred individually free in the mantle musculature of squids, whereas those of Lappetascaris sp. Type B were considerably smaller, only 3–7 mm long, and were found in capsules on the stomach wall, each capsule containing up to 50–60 larvae. It is not known whether both larval types are conspecific or belong to two different Lappetascaris species. Anisakis simplex and A. physeteris larvae were found in Onychoteuthis borealijaponica Okada and Gonatopsis borealis Sasaki, and O. borealijaponica, respectively, whereas Lappetascaris sp. Type A and Type B larvae from Thysanoteuthis rhombus Troschel, Ommastrephes bartramii (LeSueur), Onychoteuthis borealijaponica and G. borealis, and O. bartramii, respectively. The findings represent several new host records and all these parasites are reported for the first time from squids in the central North Pacific Ocean.

Toxaphene and other persistent organochlorine pesticides in three species of albatrosses from the north and south Pacific Ocean

AbstractToxaphene and other persistent organochlorine (OC) pesticides (chlordane‐related compounds [ΣCHL], DDT‐related compounds [ΣDDT], hexachlorocyclohexanes [ΣHCH], tris(p‐chloro‐phenyl)methane, hexachlorobenzene, octachlorostyrene, dieldrin) were determined in fat of Laysan albatross (Diomedea immutabilis) and in fat and eggs of blackfooted albatross (Diomedea nigripes) from the central north Pacific Ocean. The HCH isomers and chlordane‐ and DDT‐related compounds were also determined in eggs of northern royal albatross (Diomedea sanfordi) collected in New Zealand. Toxaphene was detected in fat samples at mean ± standard deviation (SD) levels ranging from 243 ± 61 ng/g wet weight in Laysan albatross to 1,020 ± 237 ng/g wet weight in blackfooted albatross. These levels were higher than ΣCHL and ΣHCH but lower than ΣDDT. In eggs of blackfooted albatross, toxaphene was the major OC pesticide, averaging 513 ng/g wet weight in two pooled samples compared with 293 ng/g wet weight for ΣDDT. Two toxaphene congeners, the octachloroborane B8–1413 (Parlar 26) and the nonachlorobornane B9–1679 (P50), comprised about 38% of total toxaphene in both albatross species. All OC compounds were present at significantly higher levels in blackfooted than Laysan albatross fat with the exception of ΣHCH, dieldrin, and octachlorostyrene. Mean levels of ΣDDT and ΣHCH in northern royal albatross eggs from New Zealand were 4 and 60 times lower, respectively, than in blackfooted albatross eggs. The pattern of OC pesticide accumulation was consistent with differences in distribution of the three species in the Pacific Ocean, with highest levels in blackfooted albatross, which feed off the west coast of North America, intermediate levels in Laysan albatross, which frequent the western Pacific, and lowest levels in northern royal albatross, which are confined to the southern oceans surrounding the Antarctic.

Toxaphene and other persistent organochlorine pesticides in three species of albatrosses from the north and south Pacific Ocean.

Toxaphene and other persistent organochlorine (OC) pesticides (chlordane-related compounds [sigmaCHL], DDT-related compounds [sigmaDDT], hexachlorocyclohexanes [sigmaHCH], tris(p-chloro-phenyl)methane, hexachlorobenzene, octachlorostyrene, dieldrin) were determined in fat of Laysan albatross (Diomedea immutabilis) and in fat and eggs of blackfooted albatross (Diomedea nigripes) from the central north Pacific Ocean. The HCH isomers and chlordane- and DDT-related compounds were also determined in eggs of northern royal albatross (Diomedea sanfordi) collected in New Zealand. Toxaphene was detected in fat samples at mean +/- standard deviation (SD) levels ranging from 243 +/- 61 ng/g wet weight in Laysan albatross to 1,020 +/- 237 ng/g wet weight in blackfooted albatross. These levels were higher than sigmaCHL and sigmaHCH but lower than sigmaDDT. In eggs of blackfooted albatross, toxaphene was the major OC pesticide, averaging 513 ng/g wet weight in two pooled samples compared with 293 ng/g wet weight for sigmaDDT. Two toxaphene congeners, the octachloroborane B8-1413 (Parlar 26) and the nonachlorobornane B9-1679 (P50), comprised about 38% of total toxaphene in both albatross species. All OC compounds were present at significantly higher levels in blackfooted than Laysan albatross fat with the exception of sigmaHCH, dieldrin, and octachlorostyrene. Mean levels of sigmaDDT and sigmaHCH in northern royal albatross eggs from New Zealand were 4 and 60 times lower, respectively, than in blackfooted albatross eggs. The pattern of OC pesticide accumulation was consistent with differences in distribution of the three species in the Pacific Ocean, with highest levels in blackfooted albatross, which feed off the west coast of North America, intermediate levels in Laysan albatross, which frequent the western Pacific, and lowest levels in northern royal albatross, which are confined to the southern oceans surrounding the Antarctic.