Quantifying the Spatial Structure of Invasive Lake Trout Salvelinus namaycush in Yellowstone Lake to Improve Suppression Efficacy

Yellowstone Lake in Yellowstone National Park, USA, has the longest ongoing suppression program for non-native lake trout (Salvelinus namaycush) in the western USA. Harvest data from the suppression program, along with data from an assessment program initiated in 2011, was used to estimate lake trout abundance and mortality rates. Abundance and biomass estimates were used to estimate stock–recruitment dynamics, which were inputs to a simulation model forecasting responses to continued suppression. Abundance increased during 1998–2012 when total annual mortality exceeded 0.59 and declined thereafter. The fishing mortality rate required to reduce abundance was 67% greater than predicted by models that used prerecruit survival estimates from the lake trout’s native range. Prerecruit survival in Yellowstone Lake was estimated at four to six times greater than native range survival rates. Simulated abundance continued to decline if recent suppression efforts were maintained. High prerecruit survival in Yellowstone Lake likely illustrates ecological release for an invasive species in an ecosystem containing few predators or competitors and demonstrates the potential pitfalls of assuming equal demographic rates for native and non-native populations.

Download Full-text

Response of non-native lake trout (Salvelinus namaycush) to 15 years of harvest in Yellowstone Lake, Yellowstone National Park

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f2011-122 ◽

2011 ◽

Vol 68 (12) ◽

pp. 2132-2145 ◽

Cited By ~ 50

Author(s):

John M. Syslo ◽

Christopher S. Guy ◽

Patricia E. Bigelow ◽

Philip D. Doepke ◽

Brian D. Ertel ◽

...

Keyword(s):

Growth Rate ◽

Population Growth ◽

Yellowstone National Park ◽

National Park ◽

Population Growth Rate ◽

Lake Trout ◽

Cutthroat Trout ◽

Salvelinus Namaycush ◽

Yellowstone Lake ◽

Yellowstone Cutthroat Trout

Introduced lake trout ( Salvelinus namaycush ) threaten to extirpate native Yellowstone cutthroat trout ( Oncorhynchus clarkii bouvieri ) in the 34 000 ha Yellowstone Lake in Yellowstone National Park, USA. Suppression (and eventual eradication) of the lake trout population is deemed necessary for the conservation of Yellowstone cutthroat trout. A US National Park Service gill-netting program removed nearly 450 000 lake trout from Yellowstone Lake from 1995 through 2009. We examined temporal variation in individual growth, body condition, length and age at maturity, fecundity, mortality, and population models to assess the efficacy of the lake trout suppression program. Population metrics did not indicate overharvest despite more than a decade of fish removal. The current rate of population growth is positive; however, it is lower than it would be in the absence of lake trout suppression. Fishing effort needs to increase above observed levels to reduce population growth rate below replacement. Additionally, high sensitivity of population growth rate to reproductive vital rates indicates that increasing fishing mortality for sexually mature lake trout may increase the effectiveness of suppression. Lake trout suppression in Yellowstone Lake illustrates the complexities of trying to remove an apex predator to restore a relatively large remote lentic ecosystem with a simple fish assemblage.

Download Full-text

Alterations in Yellowstone Lake Nitrogen Cycling Due to Introduced Lake Trout and Subsquent Decline of Yellowstone Cutthoat Trout

The UW National Parks Service Research Station Annual Reports ◽

10.13001/uwnpsrc.2006.3651 ◽

2006 ◽

Vol 30 ◽

pp. 68-74

Author(s):

Lusha Tronstead ◽

Robert Hall, Jr.

Keyword(s):

Invasive Species ◽

Nitrogen Cycling ◽

Lake Trout ◽

Salvelinus Namaycush ◽

Multiple Regression Model ◽

Secchi Disk ◽

Empirical Relationships ◽

Yellowstone Lake ◽

The Past ◽

Past Data

Invasive species may alter processes by indirectly affecting other species in the ecosystem, but indirect affects are difficult to measure and often pre-invasion data were not collected. However, models may be used with empirical relationships and available past data to reconstruct past processes. The introduction of lake trout (Salvelinus namaycush) in Yellowstone Lake may have indirect effects on nitrogen cycling and provide an opportunity to study the effects of an invasive species on lake processes. To estimate how lake trout altered nitrogen cycling in Yellowstone Lake, we measured ammonium (NH4+) uptake by phytoplankton in 2005 and estimate past NH4+ uptake using empirical relationships and past data. Using 1 5N, we measured phytoplankton uptake in 4 areas of Yellowstone Lake. Phytoplankton demanded 4.9 mg N m-2 hr- 1 during the ice-free season of 2005. Uptake was higher at warmer water temperatures and shallower Secchi disk depths (measure of phytoplankton biomass). Using relationships among uptake, water temperature, and Secchi disk depth, we estimated phytoplankton uptake in the past based on historical Secchi disk depths and water temperatures. Water temperatures have increased 0.29.C/decade and Secchi disk depths became 0.53 m/decade deeper over the past 30 years. Using our multiple regression model, phytoplankton uptake did not change between 1976 and 2006. The interaction between warmer water temperatures and deeper Secchi disk depths (a sparser algal assemblage) cancelled out resulting in no changed in modeled uptake. Therefore, when estimating past processes, we should use multiple predictors.

Download Full-text

Natural chemical markers identify source and date of introduction of an exotic species: lake trout (Salvelinus namaycush) in Yellowstone Lake

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f04-174 ◽

2005 ◽

Vol 62 (1) ◽

pp. 79-87 ◽

Cited By ~ 55

Author(s):

Andrew R Munro ◽

Thomas E McMahon ◽

James R Ruzycki

Keyword(s):

Exotic Species ◽

Lake Trout ◽

Geographic Origin ◽

Salvelinus Namaycush ◽

Chemical Markers ◽

Yellowstone Lake ◽

Otolith Sr:Ca Ratios ◽

Species Invasions ◽

Probable Source ◽

Sr:Ca Ratios

Exotic species invasions pose a pervasive threat to aquatic ecosystems worldwide, yet fundamental questions about the geographic origin and timing of invasions or introductions are frequently difficult to answer. We used natural chemical markers (Sr:Ca ratios) in otoliths to identify probable source and date of introduction of exotic lake trout (Salvelinus namaycush) into Yellowstone Lake, Wyoming, USA. Otolith Sr:Ca ratios were significantly different among lake trout known to have reared in three different Yellowstone National Park lakes (Yellowstone, Heart, and Lewis lakes) and showed little variation along the otolith axis, indicating that lake trout within each lake experienced a similar, and consistent, environmental history. In contrast, suspected transplants showed a large and rapid increase in otolith Sr:Ca ratios indicative of a marked shift to water of differing chemistry. Timing of the abrupt change in Sr:Ca ratios indicated that some lake trout were introduced into Yellowstone Lake during the late 1980s, but more recent transplants also occurred. A discriminant model identified Lewis Lake as the likely source lake for lake trout transplanted into Yellowstone Lake. Our results demonstrate that chemical signatures within otoliths can serve as an important forensic tool for identifying the probable source and date of exotic fish introductions.

Download Full-text

Evidence of successful river spawning by lake trout (Salvelinus namaycush) in the Lower Niagara River, Lake Ontario

Journal of Great Lakes Research ◽

10.1016/j.jglr.2020.12.007 ◽

2021 ◽

Author(s):

Alexander Gatch ◽

Dimitry Gorsky ◽

Zy Biesinger ◽

Eric Bruestle ◽

Kelley Lee ◽

...

Keyword(s):

Lake Trout ◽

Lake Ontario ◽

Salvelinus Namaycush ◽

Niagara River

Download Full-text

An examination of the PCB: lipid relationship among individual fish

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f97-014 ◽

1997 ◽

Vol 54 (5) ◽

pp. 1031-1038

Author(s):

C A Stow ◽

L J Jackson ◽

J F Amrhein

Keyword(s):

Salmo Trutta ◽

Lake Michigan ◽

Oncorhynchus Tshawytscha ◽

Lake Trout ◽

Coho Salmon ◽

Salvelinus Namaycush ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Strong Linear Correlation ◽

Brown Trout Salmo Trutta ◽

The Relationship

We examined data from 1984 to 1994 for five species of Lake Michigan salmonids to explore the relationship between total PCB concentration and percent lipid. When we compared mean species lipid and PCB values, we found a strong linear correlation. When we compared values among individuals, we found modest positive PCB:lipid associations in brown trout (Salmo trutta), chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), and rainbow trout (Oncorhynchus mykiss) collected during spawning, but positive associations were not apparent among nonspawning individuals. Lake trout (Salvelinus namaycush) exhibited no discernible PCB:lipid relationship. Our results are not incompatible with previous observations that contaminants are differentially partitioned into lipids within a fish, but these results do suggest that lipids are not a major factor influencing contaminant uptake.

Download Full-text

Classification of Sea Lamprey (Petromyzon marinus) Attack Marks on Great Lakes Lake Trout (Salvelinus namaycush)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f80-240 ◽

1980 ◽

Vol 37 (11) ◽

pp. 1989-2006 ◽

Cited By ~ 52

Author(s):

Everett Louis King Jr.

Keyword(s):

Great Lakes ◽

Lake Trout ◽

Petromyzon Marinus ◽

Attachment Site ◽

Sea Lamprey ◽

Salvelinus Namaycush ◽

Oral Disc ◽

Field Assessment ◽

Sea Lampreys

Criteria for the classification of marks inflicted by sea lamprey (Petromyzon marinus) into nine categories were developed from laboratory studies in an attempt to refine the classification system used in field assessment work. These criteria were based on characteristics of the attachment site that could be identified under field conditions by unaided visual means and by touching the attachment site. Healing of these marks was somewhat variable and was influenced by the size of lamprey, duration of attachment, severity of the wound at lamprey detachment, season and water temperature, and by other less obvious factors. Even under laboratory conditions staging of some wounds was difficult, especially at low water temperatures. If these criteria are to be used effectively and with precision in the field, close examination of individual fish may be required. If the feeding and density of specific year-classes of sea lampreys are to be accurately assessed on an annual basis, close attention to the wound size (as it reflects the size of the lamprey's oral disc) and character of wounds on fish will be required as well as consideration of the season of the year in which they are observed.Key words: sea lamprey, attack marks, lake trout, Great Lakes

Download Full-text

Impact of Diet on Metabolism and Swimming Performance in Juvenile Lake Trout, Salvelinus namaycush

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f89-050 ◽

1989 ◽

Vol 46 (3) ◽

pp. 384-388 ◽

Cited By ~ 26

Author(s):

F. W. H. Beamish ◽

J. C. Howlett ◽

T. E. Medland

Keyword(s):

Oxygen Consumption ◽

Swimming Speed ◽

Lake Trout ◽

Swimming Performance ◽

Salvelinus Namaycush ◽

Feeding Trial ◽

Direct Association ◽

Feeding Trials ◽

Velocity Increments ◽

Isocaloric Diets

Juvenile lake trout, Salvelinus namaycush, of similar size were fed one of three isocaloric diets, each differing in protein and lipid content. Oxygen consumption and swimming performance were measured in a recirculating water flume at intervals throughout the 70-d feeding trials (10 °C). Swimming speed was increased by stepwise velocity increments (5 cm∙s−1) and oxygen consumption was measured at each velocity between 20 and 45 cm∙s−1. Oxygen consumption for a given speed did not differ significantly throughout the feeding trial nor among the diets implying a similarity in the quality and quantity of substrate catabolized for energy. Basal metabolism (0 cm∙s−1) was also independent of diet and feeding interval. Critical swimming speed increased with dietary and carcass protein content to suggest a direct association with muscle mass and number of myofilaments.

Download Full-text

Land water linkages: influences of riparian deforestation on lake thermocline depth and possible consequences for cold stenotherms

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f97-030 ◽

1997 ◽

Vol 54 (6) ◽

pp. 1299-1305 ◽

Cited By ~ 28

Author(s):

Robert France

Keyword(s):

Thermal Stratification ◽

Lake Trout ◽

Salvelinus Namaycush ◽

Thermocline Depth ◽

Experimental Lakes Area ◽

Northwestern Ontario ◽

Riparian Trees ◽

Tree Removal ◽

Riparian Tree ◽

Land Water

The purpose of the present study was to determine if riparian deforestation would expose lake surfaces to stronger winds and therefore bring about deepening of thermoclines and resulting habitat losses for cold stenotherms such as lake trout (Salvelinus namaycush). Removal of protective riparian trees through wind blowdown and two wildfires was found to triple the overwater windspeeds and produce thermocline deepening in two lakes at the Experimental Lakes Area. A survey of thermal stratification patterns in 63 northwestern Ontario lakes showed that lakes around which riparian trees had been removed a decade before through either clearcutting or by a wildfire were found to have thermocline depths over 2 m deeper per unit fetch length compared with lakes surrounded by mature forests. Riparian tree removal will therefore exacerbate hypolimnion habitat losses for cold stenotherms that have already been documented to be occurring as a result of lake acidification, eutrophication, and climate warming.

Download Full-text