Pacific Voices

Pacific Voices: Worlds within Our Community. Burke Museum of Natural and Cultural History, Seattle, Washington, permanent installation.     

The survival of Pacific salmon in the North Pacific in the winter and spring

The effects of various factors (water temperature, food availability, predation, and the size of juveniles) on the survival of Pacific salmons during overwintering in open ocean waters are analyzed based on the data collected by expeditions of the Pacific Research Fisheries Center to the northwestern Pacific Ocean in the winter and spring seasons of 1986–1992 and 2009–2011, as well as in the summer seasons of 2004–2011. The temperature factor is unlikely to be a direct cause of the high salmon mortality in the ocean during the winter, as there is no clear evidence that it affects food availability for salmon. The biomass of forage zooplankton in the Subarctic Front zone in February and March is lower than that in April and June–July, but it does not decrease substantially in the winter months. Taking the fact into account that the total abundance of planktivorous nekton is also low in this area during the winter, food availability cannot be considered a crucial factor that has a serious influence on salmon mortality in this period. The difference in feeding intensity between salmon species and between their size groups in the winter and spring is determined by their life strategies. The observed variations in feeding intensity and lipid accumulation from autumn to spring are caused by cyclic seasonal changes in physiological processes in salmon rather than by the amount and availability of food resources. The low abundance of predators in subarctic waters and in the Subarctic Front zone in the winter also cannot reduce salmon abundance substantially. The probable relationship between the critical size of juveniles and their survival in the winter is considered using the example of a Sea of Okhotsk stock of pink salmon. The conclusion is that the size of juvenile pink salmon cannot always be used as a predictor of the values of its subsequent returns, because survival of salmon during the ocean period of life depends both on the initial conditions during downstream migration and on the ocean conditions that form in the winter. Thus, none of the factors above can be considered as strictly limiting the abundance of Pacific salmon in the winter. It is more probable that the survival of salmon in the ocean is influenced, to a lesser or greater extent, by the combined effects of abiotic and biotic factors.     

Eco-evolutionary dynamics in Pacific salmon

Increasing acceptance of the idea that evolution can proceed rapidly has generated considerable interest in understanding the consequences of ongoing evolutionary change for populations, communities and ecosystems. The nascent field of 'eco-evolutionary dynamics' considers these interactions, including reciprocal feedbacks between evolution and ecology. Empirical support for eco-evolutionary dynamics has emerged from several model systems, and we here present some possibilities for diverse and strong effects in Pacific salmon (Oncorhynchus spp.). We specifically focus on the consequences that natural selection on body size can have for salmon population dynamics, community (bear-salmon) interactions and ecosystem process (fluxes of salmon biomass between habitats). For example, we find that shifts in body size because of selection can alter fluxes across habitats by up to 11% compared with ecological (that is, numerical) effects. More generally, we show that selection within a generation can have large effects on ecological dynamics and so should be included within a complete eco-evolutionary framework.     

Depth and movement behaviour of the Pacific sleeper shark in the north-east Pacific Ocean

Satellite-linked radio telemetry was used to study the geographic movements and vertical movement behaviour of the Pacific sleeper shark Somniosus pacificus . The fish were tagged near Steller sea lion Eumetopias jubatus rookeries in the Gulf of Alaska during periods when Steller sea lions pups were most vulnerable to predation; when Steller sea lion pups first enter the water (July to August) and when Steller sea lion pups are weaned (April to May). Final locations recovered from most Pacific sleeper sharks (76%) were within 100 km of release locations, 16% were within 100–250 km and 8% were within 250–500 km. The most striking behavioural feature was their extensive, nearly continuous vertical movements. Median daily depth range was 184 m; the most time (61%) was spent between 150 and 450 m, but ascents above 100 m were common (58% of days). Median vertical movement rate was 6 km day⁻¹ and steady. The longest period of continuous vertical movement (> 60 m h⁻¹) was 330 h. Systematic vertical oscillations were most common (60%), followed by diel vertical migrations (25%) and irregular vertical movements (15%). The Pacific sleeper sharks travelled below the photic zone during the day and approached the surface at night. Pacific sleeper sharks appear to employ a stealth and ambush hunting strategy that incorporates slow vertical oscillations to search for prey, and cryptic colouration and cover of darkness to avoid detection by potential prey. The depth and geographic range of Pacific sleeper shark and Steller sea lions overlap near four important Steller sea lion rookeries in the northern Gulf of Alaska, so the potential exists for predation to occur. None of the tissues in the stomachs of the 198 Pacific sleeper sharks collected during a companion diet study, however, were identified as Steller sea lion.     

Genetic Population Structure of Pacific Hake, Merluccius productus, in the Pacific Northwest

This study presents the first protein electrophoretic study of population structure within the Georgia Basin Pacific hake Distinct Population Segment, as defined under the U.S. Endangered Species Act. Forty-one allozyme loci (29 polymorphic) were analyzed in samples from three Pacific hake spawning populations on the west coast of North America: (1) Port Susan, Puget Sound, Washington (three temporal samples); (2) south-central Strait of Georgia, British Columbia, Canada (two temporal samples); and (3) offshore of southern California (two temporal samples) (total n = 664). Mean heterozygosity over all loci was 12–13% for all populations. Within-population temporal samples were not significantly different from one another, but statistically significant differences were detected at 15 of the 29 polymorphic loci (p < 0.05) among the three populations. Differences at eight of these loci were highly significant (p < 0.001): ADA ^*, ALAT ^*, bGALA ^*, GPI-A ^*, sIDHP ^*, LDH-A ^*, MPI ^*, and PEP-B ^*. The two Georgia Basin populations were significantly different at six loci: bGALA ^*, sIDHP ^*, LDH-A ^*, MPI ^*, PGK ^*, and PGM-2 ^* (p < 0.05). Nei's genetic distance (D) was 0.0006 between Port Susan and Strait of Georgia pooled temporal samples, and 0.005 between these populations and offshore Pacific hake. F_ST was 0.02 and 0.0046 among all three populations and among the Georgia Basin populations, respectively. Both F_ST estimates were significantly greater than zero, and the results suggest a high degree of demographic isolation among all three populations.     

Some agaric distribution patterns involving Pacific landmasses and Pacific Rim

The Pacific Ocean and the “Pacific Rim” include a vast geographic area and most categories of the earth's ecological niches. As could be expected, macrofungi conform to many distribution patterns, some of which are discussed in this article. An introduction to species concepts and some other ancillary methodological considerations is followed by examples of some distributional patterns: Gondwanan, Transberingian, and island biogeographic. Some considerations of changing distributional patterns are also discussed: widening distributions, probable human mediation, and some unique cases that seem not to conform to accepted patterns. Not surprisingly, we conclude that concerted future collecting and comparison of specimens using multiple methodologies offer the only hope for understanding mushroom distributions, regardless of the geographic area of interest.     

Seabird associations in Pacific equatorial waters

Seabirds were counted along the same cruise tracks in the eastern tropical Pacific (10°øN-10°øS and 140°ø-90°øW) each spring and autumn for 8 years, 1984–1991. During spring, three species groups were apparent among eight species seen in five or more years: (1) Leach's Storm-petrel Oceanodroma leucorhoa and Wedge-rumped Storm-petrel Oceanodroma tethys , which feed on neuston by surface seizing; (2) Black-winged Petrel Pterodroma nigripennis and White-winged Petrel Pterodroma leucoptera , which feed on neuston and micronekton by surface seizing; (3) Juan Fernandez Petrel Pterodroma externa , Wedge-tailed Shearwater Puffinus pacificus and Sooty Tern Sterna fuscata , which feed on micronekton driven to the surface by foraging tuna. During autumn, only one group was identified from the seven species seen in five or more years: Leach's Storm-petrel associated with either Wedge-rumped Storm-petrel or Juan Fernandez Petrel and/or White-winged Petrel. Annual variability in assemblage composition was more extreme in the autumn and thus was similar to variation in physical and biological factors linked to the El Niño-Southern Oscillation cycle.     

西太平洋浮游动物种类多样性

西太平洋区是全球海洋生物种源中心,许多类群的最高物种多样性都出现于该区域,因此,在该区开展种类多样性的研究不仅重要和必要,而且具有在跨国尺度上进行综合管理和相互合作的迫切性。本文在西太平洋的浮游动物样品鉴定分类、编目、文献资料整理和分析的基础上,记录和编入西太平洋10个浮游动物类群2,658种(含亚种),隶属于206科675属,其中水螅水母类99科251属697种,栉水母类12科22属59种,浮游软体动物14科35属86种,介形类8科89属416种,桡足类51科156属908种,糠虾类4科58属202种,磷虾类2科8属56种,十足类8科22属105种,毛颚类5科8属48种,被囊类5科26属81种。     

Studies in Pacific Rubiaceae: VI-VIII

These studies deal with HawaiianHedyotis andGouldia, and withCoprosma in Juan Fernández. The speciesCoprosma oliveri is described as new, as isGouldia terminalis (Hook. & Arn.) Hillebr. var.pubistipula, and three forms ofHedyotis acuminata (Cham. & Schlecht.) Steud.     

Pacific Island suicide in comparative perspective

All available data for thirteen Pacific Island nations are used in a comparative analysis of suicide levels and characteristics. Age, sex and method of suicide are examined in detail. Global comparison shows Pacific rates are amongst the highest reported. Female youth rates exceed male rates in Western Samoa and amongst Fiji Indians. Method of suicide (paraquat ingestion) is instrumental in determining high rates in Western Samoa, especially in females. The broad causal theme is societal transition. Commonality and diversity are discussed.