Pre-spawning migration of adult Pacific lamprey, Entosphenus tridentatus, in the Willamette River, Oregon, U.S.A.

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 the other possessed at least 6 mid-vitellogenic oocytes (0.6 mm, mean long diameter) separate from the testes. Because premetamorphic lamprey can possess both female and male gonial cells, we hypothesize that intersex is a remnant larval trait and that these fish failed to fully develop into males during metamorphosis.

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Predicting larval metamorphosis of Pacific lamprey Entosphenus tridentatus through measurements of length and mass

Journal of Fish Biology ◽

10.1111/jfb.14436 ◽

2020 ◽

Vol 97 (3) ◽

pp. 804-816

Author(s):

Timothy A. Whitesel ◽

Michelle McGree ◽

Gregory S. Silver

Keyword(s):

Larval Metamorphosis ◽

Pacific Lamprey ◽

Entosphenus Tridentatus

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“Life histories” is a more appropriate term than “ecotypes” to describe ocean- and stream-maturing Pacific lamprey Entosphenus tridentatus

10.22541/au.159863452.24079969 ◽

2020 ◽

Author(s):

Benjamin Clemens ◽

Carl Schreck

Keyword(s):

Life Histories ◽

Pacific Lamprey ◽

Entosphenus Tridentatus

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Marine biology of the pacific lamprey Entosphenus tridentatus

Reviews in Fish Biology and Fisheries ◽

10.1007/s11160-019-09578-8 ◽

2019 ◽

Vol 29 (4) ◽

pp. 767-788 ◽

Cited By ~ 9

Author(s):

Benjamin J. Clemens ◽

Laurie Weitkamp ◽

Kevin Siwicke ◽

Joy Wade ◽

Julianne Harris ◽

...

Keyword(s):

Marine Biology ◽

Pacific Lamprey ◽

The Pacific ◽

Entosphenus Tridentatus

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Occurrence of larval Pacific lamprey Entosphenus tridentatus from Japan, detected by random amplified polymorphic DNA (RAPD) analysis

Ichthyological Research ◽

10.1007/s10228-005-0276-4 ◽

2005 ◽

Vol 52 (3) ◽

pp. 297-301 ◽

Cited By ~ 10

Author(s):

Yuji Yamazaki ◽

Norio Fukutomi ◽

Norio Oda ◽

Koichi Shibukawa ◽

Yasuo Niimura ◽

...

Keyword(s):

Rapd Analysis ◽

Random Amplified Polymorphic Dna ◽

Pacific Lamprey ◽

Entosphenus Tridentatus

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Using genetic pedigree reconstruction to estimate effective spawner abundance from redd surveys: an example involving Pacific lamprey (Entosphenus tridentatus)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2016-0154 ◽

2017 ◽

Vol 74 (10) ◽

pp. 1646-1653 ◽

Cited By ~ 9

Author(s):

S.L. Whitlock ◽

L.D. Schultz ◽

C.B. Schreck ◽

J.E. Hess

Keyword(s):

Pedigree Reconstruction ◽

Spawning Ground ◽

Pacific Lamprey ◽

Entosphenus Tridentatus ◽

Mature Fish ◽

Survey Methodologies ◽

Sexually Mature ◽

Substantial Effort

Redd surveys are a commonly used technique for indexing the abundance of sexually mature fish in streams; however, substantial effort is often required to link redd counts to actual spawner abundance. In this study, we describe how genetic pedigree reconstruction can be used to estimate effective spawner abundance in a stream reach, using Pacific lamprey (Entosphenus tridentatus) as an example. Lamprey embryos were sampled from redds within a 2.5 km reach of the Luckiamute River, Oregon, USA. Embryos were found in only 20 of the 48 redds sampled (suggesting 58% false redds); however, multiple sets of parents were detected in 44% of the true redds. Estimates from pedigree reconstruction suggested that there were 0.48 (95% CI: 0.29–0.88) effective spawners per redd and revealed that individual lamprey contributed gametes to a minimum of between one and six redds, and in one case, spawned in patches that were separated by over 800 m. Our findings demonstrate the utility of pedigree reconstruction techniques for both inferring spawning-ground behaviors and providing useful information for refining lamprey redd survey methodologies.

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