Folders: ROOT > ScienceBase Catalog > US Fish and Wildlife Service (USFWS) > Archive > Pacific Region, Region 1 > Pacific Lamprey Data Clearinghouse > Ocean ( Show all descendants )
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ROOT _ScienceBase Catalog __US Fish and Wildlife Service (USFWS) ___Archive ____Pacific Region, Region 1 _____Pacific Lamprey Data Clearinghouse ______Ocean Filters
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Abstract: Lampreys (Petromyzontiformes) have persisted over millennia and now suffer a recent decline in abundance. Complex life histories may have factored in their persistence; anthropogenic perturbations in their demise. The complexity of life histories of lampreys is not understood, particularly for the anadromous Pacific lamprey, Entosphenus tridentatus Gairdner, 1836. Our goals were to describe the maturation timing and associated characteristics of adult Pacific lamprey, and to test the null hypothesis that different life histories do not exist. Females exhibited early vitellogenesis – early maturation stages; males exhibited spermatogonia – spermatozoa. Cluster analyses revealed an “immature” group and a...
Abstract: River lamprey (Lampetra ayresi) enter the Strait of Georgia from the Fraser River and feed almost exclusively on Pacific herring (Ckupea harenglas) and salmon (Oncsrhyncheas spp.). Although the major prey of river lamprey is Pacific herring, the greater effect of lamprey predation was on the populations sf chinook (0. tshawyfscha) and coho (0. kisutch) salmon. In 1990 and 1991, river lamprey killed a minimum of 20 million and 18 million chinook salmon, respectively, and a minimum of 2 million and 10 million coho salmon in the same years. In 1991, river lamprey in the Fraser River plume killed an equivalent of approximately 65 and 25% sf the total Canadian hatchery and wild production of coho and chinook...
Metamorphosis in harnpetra ayresi begins in July but is not completed until approximately April of the following year when the oesophagus opens. The prolonged period of metamorphosis differs from that of other lamprey species and may have evolved in response to the pattern of discharge of the Fraser River. Prior to the opening of the oesophagus, some metamorphosing k. ayresi congregate just upstream of the salt water that moved into the river from the ocean. Soon after the oesophagus opens, lampreys are able to osn-soreguiate in salt water and enter the Strait of Georgia from May to july. Maximum numbers gs to sea in early June, correlated with the maximum discharge from the Fraser River. Laboratory studies indicated...
Abstract —Results of long-term research on the spatial and vertical distribution of the Pacific lamprey Lampetra tridentata (Richardson, 1836) (the family Petromyzontidae) in the North Pacific, and data on its size structure are submitted. It was shown, that L. tridentate reached its greatest number in the Bering Sea. The maximum concentration of the Pacific lamprey was observed all year round about Navarin Cape, in the Koryak shelf area, at the East Aleutian Islands and at the west coast of the USA, which, apparently, spoke of the increased number of its prey there. On the bottom, the Pacific lamprey was the most numerous at depths of less than 500 m, and in the pelagic, in the upper 100-meter layer. The length...
Abstract: We report the incidence of male intersex in adult Pacific lamprey (Entosphenus tridentatus (Richardson, 1836)) during their pre-spawning migration in fresh water. Although “hermaphrodites” have been suggested in other adult lampreys, this is the first detailed description and discussion of this phenomenon. A total of 0.5% of our adult Pacific lamprey from Willamette Falls (2 out of 427 adults) were intersex, with oocytes in the testes. This phenomenon was identifiable only by histological examination. The testes of the intersex males were immature, in the beginning stages of meiosis. One intersex male possessed primary growth or perinucleolar stage oocytes loosely interspersed throughout the testes, and...
Sex determination mechanisms in fishes lie along a genetic-environmental continuum and thereby offer opportunities to understand how physiology and environment interact to determine sex. Mechanisms and ecological consequences of sex determination in fishes are primarily garnered from teleosts, with little investigation into basal fishes. We tagged and released larval sea lamprey (Petromyzon marinus) into unproductive lake and productive stream environments. Sex ratios produced from these environments were quantified by recapturing tagged individuals as adults. Sex ratios from unproductive and productive environments were initially similar. However, sex ratios soon diverged, with unproductive environments becoming...
The four goals of the Ocean Phase subgroup are: 1. To explicitly identify the many information gaps in the ocean phase of the life history of anadromous lampreys (Western River Lamprey and Pacific Lamprey). 2. To identify existing research, monitoring, and evaluation (RM&E) programs that may have data that could be used to fill in some of these information gaps. 3. To prioritize particular RM&E projects to be recommended and executed by researchers in the near future. 4. To set forth a plan for executing prioritized RM&E projects.
Arctic Lamprey Lethenteron camtschaticum and Pacific Lamprey Entosphenus tridentatus are ecologically and culturally important anadromous, parasitic species experiencing recent population declines in the North Pacific Ocean. However, a paucity of basic information on lampreys feeding in the ocean precludes an incorporation of the adult trophic phase into our understanding of lamprey population dynamics. The goal of this research was to provide insight into the marine life-history stage of Arctic and Pacific lampreys through lamprey-host interactions in the eastern Bering Sea. An analysis of two fishery-independent surveys conducted between 2002 and 2012 in the eastern Bering Sea revealed that Arctic Lampreys were...
Abstract—Little is known about the basic biology and ecology of most native lampreys, including the use of estuaries by anadromous lampreys. To address this deficiency, we provide the first analysis of anadromous western river (Lampetra ayresii) and Pacific (Entosphenus tridentatus) lampreys in the Columbia River estuary, using data from 2 fish assemblage studies that span 3 decades (1980–1981 and 2001–2012). Pacific lamprey juveniles and adults in the estuary clearly were separated by size, whereas western river lamprey formed one continuous size distribution. Pacific lamprey juveniles and adults were present in the estuary in winter and spring, and western river lamprey were present from spring through early fall....
ABSTRACT: Sea lampreys, Petromyzon marinus, are invasive to the Laurentian Great Lakes where they have decimated native fishes. Great Lakes sea lampreys have been subjected to control measures for several decades, and the drive to control them has led to major advances in understanding their biology and in informing management. In contrast, anadromous sea and Pacific (Entosphenus tridentatus) lampreys have co-evolved with their oceanic prey. Both of these anadromous lampreys are in decline, and a limited amount of information on their biology has stymied conservation. The tendency has been to make biological inferences about anadromous lampreys based on the Great Lakes sea lamprey without justifiable evidence. We...
In this report we utilized statistical models and G.I.S-based approaches to analyze available life cycle, abundance and distribution data from the last 80 years on Pacific lamprey (Entosphenus tridentatus) and Pacific eulachon (Thaleichthys pacificus), and determine how climate change may potentially impact these species in the Columbia River basin. Both species have experienced substantial declines in this basin, and are in urgent need of protection and restoration. While data on these species have incomplete spatial and temporal coverage in this region, some inferences can be derived on possible adverse effects of climate change and subsequent impacts on persistence and resilience of populations. The quantified...
Seasonal abundance, size, and prey selection of Pacific and river lamprey the Columbia River estuary
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