Benjamin J. Clemens

Similarities, differences, and unknowns in biology and management of three Parasitic lampreys of North America.

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 identify areas in which key information is missing for the juvenile (parasitic feeding) phase and adult freshwater spawning migrations, and compare and contrast information for these lampreys. Our comparisons reveal major differences, some intriguing similarities, and key unknowns that will requir...

Translocating Adult Pacific Lamprey within the Columbia River Basin: State of the Science

ABSTRACT The Pacific lamprey (Entosphenus tridentatus) is in decline in the Columbia River Basin, and translocating adult lamprey to bypass difficult migration corridors has been implemented since 2000. We describe and report results from two current translocation programs, provide context for use of translocation, and discuss potential benefits, risks, and uncertainties. Both translocation programs appear to have increased the number of spawning adults and the presence of larvae and juveniles; however, any subsequent increase in naturally spawning adults will require at least one, and likely more, generations to be realized. It was seen that the number of adults entering the Umatilla River increased beginning four years after the first translocations. Potential benefits of translocation programs are increased pheromone production by ammocoetes to attract adults, increased lamprey distribution and abundance in target areas, increased marine-derived nutrients, and promotion of tribal culture. Potential ris...

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

We describe the migration distances and timing of the adult Pacific lamprey, Entosphenus tridentatus, in the Willamette River Basin (Oregon, U.S.A.). We conducted aerial surveys to track radio-tagged fish upstream of a major waterfall and hydropower complex en route to spawning areas. We detected 24 out of the 43 fish that passed the waterfall-hydropower complex. Of the detected fish, 17 were detected multiple times. Their maximum migration distance upstream in the mainstem Willamette approximated a normal distribution. The maximum distance migrated upstream did not significantly correlate with total body length (r = −0.186, P = 0.385) or date that the fish passed Willamette Falls (r = −0.118, P = 0.582). Fish migrated primarily during the spring to early summer period before stopping during the summer, when peak river temperatures (≥20°C). However, at least three fish continued to migrate upstream after September. Behavior ranged from relatively slow migration, followed by holding; to rapid migration, followed by slow migration further up in the basin. This study provides a basis for informing more detailed research on Pacific lamprey in the future.

Conservation Challenges and Research Needs for Pacific Lamprey in the Columbia River Basin

The Pacific Lamprey Entosphenus tridentatus, an anadromous fish native to the northern Pacific Ocean and bordering freshwater habitats, has recently experienced steep declines in abundance and range contractions along the West Coast of North America. During the early 1990s, Native American tribes recognized the declining numbers of lamprey and championed their importance. In 2012, 26 entities signed a conservation agreement to coordinate and implement restoration and research for Pacific Lamprey. Regional plans have identified numerous threats, monitoring needs, and strategies to conserve and restore Pacific Lamprey during their freshwater life stages. Prime among these are needs to improve lamprey passage, restore freshwater habitats, educate stakeholders, and implement lamprey-specific research and management protocols. Key unknowns include range-wide trends in status, population dynamics, population delineation, limiting factors, and marine influences. We synthesize these key unknowns, with a focus on ...

A Survey of Steelhead Age and Iteroparity Rates from a Volunteer Angler Program in the Willamette River Basin, Oregon

AbstractThe iteroparous life history of steelhead Oncorhynchus mykiss can provide genetic variability and increase recruitment, thereby sustaining populations. Steelhead are difficult to survey given that (1) they spawn during high river flows, which can flush carcasses away; (2) they spend a short time on the spawning grounds; (3) nonspawning fish are elusive; and (4) adults that do not die after spawning can evade surveyors. An angler volunteer program was implemented in Oregon to monitor steelhead populations. Recreational anglers collected scales from 2,216 steelhead in the Willamette River basin during 1981–1994; the scales were used to estimate ages and iteroparity rates. A freshwater age of 2 and a saltwater age of 2 were the most common, followed by saltwater ages 3 and 4. The incidence of iteroparity was greater among female steelhead than among males and was greater for winter-run steelhead than for summer-run fish. Wild fish had a higher incidence of repeat spawning than hatchery fish, which ma...

Spawning Patterns of Pacific Lamprey in Tributaries to the Willamette River, Oregon

AbstractAddressing the ongoing decline of Pacific Lamprey Entosphenus tridentatus across its range along the west coast of North America requires an understanding of all life history phases. Currently, spawning surveys (redd counts) are a common tool used to monitor returning adult salmonids, but the methods are in their infancy for Pacific Lamprey. To better understand the spawning phase, our objective was to assess temporal spawning trends, redd abundance, habitat use, and spatial patterns of spawning at multiple spatial scales for Pacific Lamprey in the Willamette River basin, Oregon. Although redd density varied considerably across surveyed reaches, the observed temporal patterns of spawning were related to physical habitat and hydrologic conditions. As has been documented in studies in other basins in the Pacific Northwest, we found that redds were often constructed in pool tailouts dominated by gravel, similar to habitat used by spawning salmonids. Across the entire Willamette Basin, Pacific Lamprey...

Persistence of Triploid Grass Carp in Devils Lake, Oregon

Abstract Grass carp Ctenopharyngodon idella are sometimes used as a biological tool for managing aquatic vegetation in reservoirs. Sterile, triploid fish were stocked in Devils Lake, Oregon, during 1986, 1987, and 1993 to control aquatic vegetation. We present a case study for using multiple measures on the same fish to determine whether illegal stocking of fertile, diploid grass carp occurred. An investigation into the estimated age of a dead grass carp found in Devils Lake suggested that it was significantly younger than would otherwise be expected, given the only stocking events occurred during 1986, 1987, and 1993. To determine whether illegal stocking or reproduction by presumed sterile grass carp had occurred in Devils Lake, we conducted a study that balanced the needs of lethally sampling grass carp for biological measures with the socially and politically sensitive sentiment of the pro–grass carp citizenry of Devils Lake. These considerations, in combination with a low catch per-unit effort, resul...

Primitive fishes: environmental adaptations and persistence McKenzie DJ, Farrell AP, Brauner CJ (eds) (2007) Primitive fishes, Vol. 26, Fish physiology, Academic Press, Amsterdam, 562 pp, US

Keywords Agnatha.Sarcopterygii.Polypteriformes.Acipenseriformes.Holosteans.PrimitiveAnyone who has seen a lamprey, sturgeon, bowfin, orany other ‘primitive fish’ can attest to the mystique ofthese animals. Primitive fishes can (in my case) evokethe wonder experienced as children over dinosaurs, agroup that is younger in geologic time than manyprimitive fishes (Kardong 1995). The ancient lineageand persistence of primitive fishes through time makesthem amenable to studies of phylogeny and evolution.Primitive fishes are especially interesting from ananthropomorphic view, as some, lungfishes and coela-canths, may be more closely related to humans than toother fishes (Maisey 1996;Janvier,Figure1.3inChapter 1; Youson, Chapter 9). In my case, the ancientlineage of primitive fishes also makes them interestingto study with respect to their physiological adaptationsto their present and past environments. Many of theprimitive fishes have changed very little in appearanceover time and it is a wonder that they have persisted forso long.The authors of the book chapters occasionallyspeculate about how the physiology of primitive fishesadapted them to past environments (Chapter 1) or hasenabledthemtopersistincurrentenvironments(Chapter10). For the most part, however, care is taken by allauthors(especiallyJanvierinChapter1)toacknowledgethat the physiology we see now may not indicateadaptation to past environments (witnessed by themarine origin of lungfishes, which now only exist infreshwater; Janvier, Chapter 1). Fossils typically captureonlythecalcifiedskeletalremainsoforganismsandomitthesoftanatomyinwhichmanyphysiologicalprocessesoccur. As a result, fishes lacking a rigid, calcifiedskeleton have relatively poor fossil records (e.g.,lampreys; Janvier, Chapter 1). Skeletons have theirlimitations for fishes with bony elements, as functioncannot always be deduced from morphology (e.g., seeWainwright 2007). ‘In sum, very few fossil data aredirectly informative to primitive vertebrate physiolo-gists’ (Janvier, Chapter 1, pg. 40).‘Primitive Fishes’ is a well-bound book that staysopen on your desktop for easy access and reference. Ipreferred the ‘old-style’ covers of past books in theFish Physiology series (Volumes 1–13). However thecover of ‘Primitive Fishes’ presents an attractive colorscheme with a whimsical and arresting line drawing ofprimitive fishes by the author of Chapter 1, Janvier.My only complaint about how the book is ‘puttogether’ is that the color inserts for figures are often,but not always, inserted several pages away from the