Tommi Linnansaari

Tommi Linnansaari
University of New Brunswick · Canadian Rivers Institute, Department of Biology and Faculty of Forestry and Environmental Management

Ph.D.

About

80
Publications
33,556
Reads
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1,234
Citations
Introduction
I am a fish ecologist current holding an Atlantic salmon Research Chair at the University of New Brunswick, where I am a research coordinator of the Collaboration for Atlantic Salmon Tomorrow (CAST) consortium. The CAST research takes place on the Miramichi River, New Brunswick. I continue my research in the Mactaquac Aquatic Ecosystem Study (MAES), a large multi-disciplinary project trying to better understand the end of life options for a large hydropower dam. My reseacr portfolio in MAES includes fish passage studies for species like American eel and Atlantic salmon, however, it also includes habitat modelling and other aquatic animals like freshwater mussels. I am also involved in a research project trying to better understand aquatic connectivity in the Restigouche River.
Additional affiliations
July 2021 - present
University of New Brunswick
Position
  • Professor
Description
  • Atlantic Salmon Research Chair
July 2017 - June 2021
University of New Brunswick
Position
  • Professor (Associate)
Description
  • Atlantic Salmon Research Chair
September 2013 - June 2017
University of New Brunswick
Position
  • Research Associate
Description
  • Co-leader of the Mactaquac Aquatic Ecosystem Study
Education
May 2003 - May 2009
University of New Brunswick
Field of study
  • Biology
September 1998 - April 2003
University of Helsinki
Field of study
  • Fisheries Science

Publications

Publications (80)
Preprint
Full-text available
Earth’s riverine fishes utilize a suite of reproductive guilds, broadly following four guilds: nest guarders, broadcast pelagic spawners, broadcast benthic spawners and nest non-guarders ¹ , ² , and these guilds utilize different mechanisms to aerate eggs 3,4 . Globally, river fishes populations are declining ⁵ , and spawning habitat rehabilitation...
Article
Full-text available
An epigenetic basis for transgenerational plasticity in animals is widely theorized, but convincing empirical support is limited by taxa-specific differences in the presence and role of epigenetic mechanisms. In teleost fishes, DNA methylation generally does not undergo extensive reprogramming and has been linked with environmentally-induced interg...
Article
Full-text available
In recent decades, there has been an increase in conservation and restoration projects targeting Atlantic salmon (Salmo salar – AS), as populations in eastern Canada decline. Missing however, is an understanding of thermo‐hydraulic habitat use by adult AS during summer, and thus the actual benefits of altering in‐river physical structures. Here, we...
Article
Full-text available
The Striped Bass Morone saxatilis is an apex predator that supports recreational, commercial, and First Nations traditional fisheries in the Miramichi River, New Brunswick, Canada. Historic exploitation resulted in steep population declines, forcing a complete fisheries moratorium in 2000. After 13 years of recovery, a recreational fishery was reop...
Article
Full-text available
Physical habitat models represent a widely used tool in river management, yet, there is a growing consensus—particularly for large rivers—that fundamental principles have limits, and it is evident that improved methodologies for assessment and design are needed. Here, we suggest a framework that takes steps towards resolving some of these issues, u...
Article
Full-text available
The expansion of hydropower in combination with the already existing infrastructure and a changing climate are significantly influencing the world’s rivers. The resulting alteration in flow regimes is expected to strongly affect fish habitat and associated fish communities both spatially and temporally. Using habitat modelling, this study identifie...
Article
Full-text available
Imaging sonars, such as the Adaptive Resolution Imaging Sonar (ARIS), provide high‐resolution sonar data that is used in fisheries research and management. While sonar methods have enormous potential for making population estimates, species identification via sonar remains an unresolved challenge. One method that may overcome this challenge involve...
Article
Full-text available
Broadening our understanding of river thermal variability is of paramount importance considering the role temperature plays in aquatic ecosystem health. At the catchment-scale, spatial statistical river network models (SSN) are popular for catchment-scale analyses of river temperature, as these are less ‘data hungry’ than other modelling methods, a...
Preprint
Full-text available
In recent decades there has been an increase in conservation and restoration projects targeting Atlantic salmon (Salmo salar — AS), as populations in eastern Canada decline. Missing however, is an understanding of thermo-hydraulic habitat use by adult AS during summer, and thus the actual benefits of altering in-river physical structures. Here, we...
Article
Full-text available
Tracking 47 post‐spawned adult Atlantic salmon Salmo salar L. in a hydropower‐regulated river through autumn, winter, and spring revealed that winter survival was 56% and 75% in the two study years, respectively, with higher mortality of males than females (50% vs. 33% and 100% vs. 13%, respectively). Some kelts (n = 7) displayed non‐directed movem...
Article
Full-text available
Imaging sonars, such as the Adaptive Resolution Imaging Sonar (ARIS; Sound Metrics Corp.) produce continuous stream of sonar video footage, and they are commonly used for counting and sizing migrating fish in rivers. Although automated methods have been developed for processing imaging sonar data, manual analysis of the data is still common in fish...
Article
Full-text available
River temperature exerts a critical control on habitat for aquatic biota. As the climate warms in eastern Canada, threats to habitats of cold‐water species will increase, underpinning the necessity to develop an understanding of landscape‐scale, thermal regimes of flowing waters. We assessed the performance of spatial statistical network (SSN) mode...
Preprint
Full-text available
An epigenetic basis for transgenerational plasticity is widely theorized but convincing empirical support is limited by taxa-specific differences in the presence and role of epigenetic mechanisms. In teleost fishes, DNA methylation does not undergo extensive reprogramming and has been linked with environmentally-induced intergenerational effects, b...
Article
Full-text available
Atlantic Salmon Salmo salar spawning success is challenged when migratory routes to natal streams are obstructed by hydropower generation stations and reservoirs which lack directional cues, potentially causing migratory delay. This study used 74 acoustic tagged adult Atlantic Salmon during their spawning migrations to quantify migratory success, r...
Article
Full-text available
Juvenile striped bass (age-1) of distinct genetic ancestry were re-discovered in the Saint John River, New Brunswick in 2014 after a 35 yr hiatus of recognition. These juveniles were determined to be highly genetically divergent from all possible source populations, hypothesized to be of Saint John River ancestry, and thus considered evidence of th...
Article
Full-text available
Winter habitat selection by Striped Bass (Morone saxatilis) has been described as opportunistic, but due to the length and severity of winter at its northern range, winter habitats in the north are predicted to be restricted in distribution and carefully selected. Here we describe the locations and environmental conditions supporting winter aggrega...
Article
Altered rivers and managed flows are a hallmark of civilization and dams are a principal agent of alteration. Peak dam construction occurred at the turn of the last century in Western countries, and many of the largest dams are reaching the end of their service life. As a result, dam operators are increasingly facing a complex renewal/removal decis...
Article
Full-text available
Imaging sonars are used around the world for fish population monitoring. The accuracy of the length measurements has been reported in multiple studies for relatively short (< 15 m) ranges and high image resolution. However, imaging sonars are often used at longer ranges (i.e. , > 15 m) where the images produced from sonar returns become less detail...
Article
Full-text available
Flow‐related changes of physical habitat represent a potentially significant environmental filter determining the presence and composition of fish assemblages in rivers. The meso‐scale (10⁰‐10³ m) of river habitat has been identified as an appropriate resolution to model linkages between fish and their abiotic environment that are relevant, yet log...
Article
Full-text available
Modelling the linkage between physical habitat and aquatic organisms on multiple spatial scales has become an important tool in the management of rivers. The mesoscale (100–102 m) represents an intermediate resolution in modelling that bridges the gap between available resources and conservation efforts for riverine species. However, existing mesoh...
Article
Full-text available
The advent of remotely-sensed high-resolution imagery has led to the development of methods to map river bathymetry. In this study, we utilized high-resolution imagery to map river depth and quantify hydraulic habitats at the catchment-scale (> 1000 km2) during low flows. Using 0.3 m airborne multi-spectral imagery, we mapped contiguous river depth...
Article
Full-text available
Migration rates, delay, timing, and success of acoustic-tagged Atlantic salmon (Salmo salar) pre-smolts (n = 120) and smolts (n = 57) are reported as they moved through the large Mactaquac Generating Station (MGS) reservoir and subsequently the lower Saint John River (SJR). The potential relationship between fish movements and the MGS operations wa...
Article
Full-text available
Fish assemblages in large rivers are governed by spatio‐temporal changes in habitat conditions, which must be accounted for when designing effective monitoring programmes. Using boat electrofishing surveys, this study contrasts species richness, catch per unit effort (CPUE), total biomass, and spatial distribution of fish species in the Saint John...
Article
Anthropogenic influences, including climate change, are increasing river temperatures in northern and temperate regions and threatening the thermal habitats of native salmonids. When river temperatures exceed the tolerance levels of brook trout and Atlantic salmon, individuals exhibit behavioural thermoregulation by seeking out cold‐water refugia –...
Article
Full-text available
In 1979, the Shortnose Sturgeon (Acipenser brevirostrum) population of the Saint John River, New Brunswick, was estimated at 18,000 ± 5400 individuals. More recently, an estimate of 4836 ± 69 individuals in 2005, and between 3852 and 5222 individuals in 2009 and 2011, was made based on a single Shortnose Sturgeon winter aggregation in the Kennebeca...
Article
Full-text available
Acoustic telemetry manufacturers report estimated detection ranges under idealized conditions, but environmental conditions such as water depth, substrate type, and turbulence can affect the range of reliable detection. Range testing of low (Vemco V7 136 dB re 1µPa@1m) and high power (V13 147 dB re 1µPa@1m) acoustic transmitters (tags) was performe...
Article
Full-text available
The native striped bass (Morone saxatilis) population of the Miramichi River, New Brunswick is undergoing an unprecedented recovery while Atlantic salmon (Salmo salar) numbers within that system continue to decline. Atlantic salmon smolt depart from the Miramichi system during the striped bass spawning period and it is hypothesized that elevated st...
Article
Full-text available
The native striped bass (Morone saxatilis) population of the Miramichi River, New Brunswick is undergoing an unprecedented recovery while Atlantic salmon (Salmo salar) numbers within that system continue to decline. Atlantic salmon smolt depart from the Miramichi system during the striped bass spawning period and it is hypothesized that elevated st...
Article
Groundwater can be important in regulating stream thermal regimes in cold, temperate regions and as such, it can be a significant factor for aquatic biota habits and habitats. Groundwater typically remains at a constant temperature through time, i.e., it is warmer than surface water in the winter and cooler in the summer. Further, small tributaries...
Article
Full-text available
The development of consumer hydroacoustic systems continues to advance, enabling the use of low-cost methods for professional mapping purposes. Information describing habitat characteristics produced with a combination of low-cost commercial echosounder (Lowrance HDS) and a cloud-based automated data processing tool (BioBase EcoSound) was tested. T...
Article
Full-text available
Plankton community samples from a reservoir were compared to samples from a river downstream of a large hydroelectric generating station on the lower Saint John River, New Brunswick, Canada. The study focused on spatiotemporal variation of the plankton communities and their association with physicochemical parameters in the reservoir–downstream riv...
Article
Full-text available
Freshwater mussels are a significant component of freshwater ecosystems and often make up the largest biomass within these systems. However, their habitat is often subject to impacts such as changes in water quality or hydraulic stressors related to dams. Using snorkelling surveys, this study identified the presence, relative abundance, and spatial...
Article
Full-text available
Climate change is expected to increase the frequency and magnitude of extreme thermal events in rivers. The Little Southwest Miramichi River (LSWM) and the Ouelle River (OR) are two Atlantic salmon (Salmo salar) rivers located in eastern Canada, where in recent years, water temperatures have exceeded known thermal limits (~23°C). Once temperature s...
Article
Full-text available
Eurasian Water-milfoil (Myriophyllum spicatum L.) is regarded by conservation practitioners as one of the most challenging invasive aquatic plants to manage. Owing to its broad tolerance to environmental conditions, vegetative propagation, and rapid establishment and growth, M. spicatum introductions have the potential to drastically alter macrophy...
Article
Full-text available
Striped Bass in Canadian waters occur at the most northern extent of the species range. At these latitudes, overwintering represents a significant portion of annual activities (Nov- May). During the winter period, Striped Bass generally occupy inland waterways, aggregate densely, feed little, and conduct minimal movements rendering them vulnerable...
Article
Full-text available
Chromosomal inversions have been implicated in facilitating adaptation in the face of high levels of gene flow, but whether chromosomal fusions also have similar potential remains poorly understood. Atlantic salmon are usually characterized by population structure at multiple spatial scales; however, this is not the case for tributaries of the Mira...
Article
Full-text available
Following a failed spawning event in 1975 and the suspected absence of recent spawning by Striped Bass Morone saxatilis in the Saint John River, New Brunswick, the native Striped Bass population has been considered extirpated. Non-native migratory Striped Bass, however, still frequent the river, and a remnant, likely native, population may still ex...
Preprint
Full-text available
Genomic data provide the means to investigate the genetic basis of local adaptation and provide information about the forces structuring populations. Atlantic salmon are typically characterized by hierarchical population structure at multiple spatial scales; however, this is not the case for a large river in North America. To resolve genetic relati...
Article
Full-text available
Top predators, such as the Striped Bass Morone saxatilis and Muskellunge Esox masquinongy, can impact food webs and alter ecosystem structure through the regulation of prey populations. Within the Saint John River, New Brunswick, Canada, both predators have long been hypothesized to impart significant mortality on smolts of the endangered Atlantic...
Article
Full-text available
Streams fluctuate in water flow because of natural (e.g., rain) and human-induced events (e.g., hydropeaking). Magnitude, frequency, and predictability of these events can have drastic consequences for fish populations. We studied how rapid modifications of water flow affect diel activity and foraging mode of juvenile Arctic charr Salvelinus alpinu...
Article
Full-text available
The frequency of extreme thermal events in temperate freshwater systems is expected to increase alongside global surface temperature. The Miramichi River, located in eastern Canada, is a prominent Atlantic salmon (Salmo salar) river where water temperatures can exceed the proposed upper thermal limit for the species (~27°C). Current legislation clo...
Article
Full-text available
The Striped Bass Morone saxatilis of the Saint John River, New Brunswick, is an enigma, having now existed in a state of uncertain species status for more than four decades. Despite a well-established historical record of adult occurrence in large numbers, the available literature, historical accounts, and status reports contain no evidence for the...
Poster
Full-text available
Recent environmental flows research has focused on the question of ”How much water does a river need?” and the development of methods for the development and assessment of sustainable strategies. Application methods include traditional hydrological and hydraulic rating methods that only incorporate historical streamflow data to habitat simulation a...
Article
Full-text available
Background: Fish fin is a widely used, non-lethal sample material in studies using stable isotopes to assess the ecology of fishes. However, fish fin is composed of two distinct tissues (ray and membrane) which may have different stable isotope values and are not homogeneously distributed within a fin. As such, estimates of the stable isotope valu...
Data
Stable isotope values. A data file containing all carbon (δ13C), nitrogen (δ15N), hydrogen (δ2H) and oxygen (δ18O) stable isotope ratios generated during this study. (XLSX)
Technical Report
Full-text available
The science of fish passage has a long history and many technologies exist to attempt to provide fish passage both up- and downstream of hydropower projects. Traditional upstream passage solutions include various technical (baffle and pool-and-weir fish ladders) and nature-like fishways which allow volitional passage of selected target species. Non...
Technical Report
Full-text available
Freshwater resources are under increasing threat from anthropogenic activities. Increasing societal demands have led to substantial flow alterations in rivers across Canada and globally. Flow alteration can impact the physical attributes of rivers which in turn results in ecological changes that can impact the health of river ecosystems. In additio...
Technical Report
Full-text available
A Fish Passage Experts Workshop was held on 3-4 November 2014, in Fredericton, NB, where nine of the world’s leading experts on fish passage shared best practices and lessons learned from various rivers and projects around the world. The objectives of the meeting were to learn about and discuss our current and best understanding of fish passage sci...
Article
Summer water temperatures are rising in many river systems in North America, and this warming trend is projected to intensify in the coming decades. One option for cold-water fish to alleviate thermal stress in summer is by aggregating in discrete cold-water plumes that provide thermal refuge from high ambient river temperatures. Reliance on cold-w...