Eduardo Martins

University of Northern British Columbia · Department of Biology

The growing demand for hydropower has influenced the connectivity of freshwater ecosystems. Entrainment through turbines has been identified as one factor which can potentially affect fish populations within and downstream of reservoirs and, in some cases, large numbers of entrained fish are recorded. There is a need to understand and assess specie...

The recent large-scale hydropower development in the Amazon basin has raised concerns about the impacts on the movements of migratory fishes such as goliath catfish (Brachyplatystoma spp.). In the Madeira River, the efficiency of a 1400-m long fishway in the Santo Antônio hydropower plant (SAE HPP) was evaluated between 2012 and 2016 using telemetr...

Sustainable global energy production is back-stopped by hydropower which is responsible for a significant share of the green energy produced worldwide. Hydropower, however, does not come without some environmental impacts but has worked to reduce those impacts. Here, we discuss the historical, legislative, and design configurations of hydropower fa...

• Arapaima (Arapaima sp.) are highly overexploited fish endemic to the Amazon basin. Because the fish are obligate air‐breathers, it is possible to use surface‐breathing events to count individuals visually for population censuses important for conservation, yet uncertainties remain about body size and environmental influences on air‐breathing inte...

Pacific salmon undertake iconic homeward migrations where they move from ocean feeding grounds to coastal rivers where they return to natal spawning sites. However, this migration is physiologically challenging as fish have to navigate past predators, nets, hooks, and dams while dealing with variable flows, warm water temperatures, and pathogens. T...

Migrations of juvenile salmon smolts are generally high‐risk, with predation often implicated in reduced survival. In theory, smolts can maximise survival via depensation, or synchronising movements to swamp predators. Depensation, however, is difficult to assess in the wild. Accounting for depensation could also generate more realistic telemetry‐b...

Migration is a widespread but highly diverse component of many animal life histories. Fish migrate throughout the world's oceans, within lakes and rivers, and between the two realms, transporting matter, energy, and other species (e.g., microbes) across boundaries. Migration is therefore a process responsible for myriad ecosystem services. Many hum...

We used a combination of radio and acoustic telemetry to assess the movements of large catfish (Pimelodidae) in the Xingu River, a clearwater tributary of the Amazon River in Brazil. A total of 121 Phractocephalus hemioliopterus and 61 Pseudoplatystoma punctifer were tagged for monitoring within a 685 km segment, including the Belo Monte Hydroelect...

The genetic analysis of Brachyplatystoma platynemum individuals sampled from the lower Madeira River reinforces the existence of two structured populations in the Amazon Basin (Madeira and Amazon populations). However, the recapture of an individual from the Amazon population in the Solimões River, which was telemetry‐tagged in the Madeira River af...

Telemetry, or the remote monitoring of animals with electronic transmitters and receivers, has vastly enhanced our ability to study aquatic animals. Radio telemetry, acoustic telemetry, and passive integrated transponders are three common technologies that generate detection data – time‐stamped tag‐specific records that are logged by receivers. We...

Dorsal muscle and adipose fin samples collected from sockeye salmon (Oncorhynchus nerka) on the spawning grounds were used to investigate the dependence of tissue stable isotope values (δ¹³C and δ¹⁵N) on population origin and sex. Tissue stable isotope values differed by sex in all populations, presumably due to differences in male and female energ...

Potadromous fishes are vulnerable to involuntary entrainment through hydropower turbines. However, turbines can also provide a downstream passage route for potadromous fish. Here, we review evidence for turbine entrainment and passage in potadromous fish, and evaluate the effects of these processes on upstream and downstream populations. We develop...

Impoundments and diversions in freshwater corridors can alter the availability and concentration of natal water cues that migratory salmon rely on to guide homing during spawning migrations, although this has rarely been examined. By combining radiotelemetry and noninvasive biopsy, we provide the first detailed account of the effects of varying nat...

Bull trout (Salvelinus confluentus) are a thermally sensitive cold-water species with a threatened conservation status across much of North America. To improve our understanding of bull trout thermal ecology, we tagged more than 150 adults with temperature sensing acoustic biotelemetry transmitters and monitored the animals in a British Columbia re...

The Amazon river basin is considered the new frontier for dam construction in Brazil and the most affected species are long-distance migrators, especially the large catfish (Pimelodidae). We used radio and/or acoustic telemetry to investigate movements of catfish species after impoundment by two big dams in the Madeira River; along a 700-rkm stretc...

1.The variation in migration that comprise partial diel migrations, putatively occur entirely as a consequence of behavioural flexibility. However, seasonal partial migrations are increasingly recognised to be mediated by a combination of reversible plasticity in response to environmental variation and individual variation due to genetic and enviro...

Despite many similarities and intuitive links between individual dietary specialisation and behavioural inter-individual variation, these phenomena have been studied in isolation, and empirical data confirming relationships between these intraspecific variance sources are lacking. Here we use stable isotope analysis and acoustic telemetry to test t...

Freshwater fish move vertically and horizontally through the aquatic landscape for a variety of reasons, such as to find and exploit patchy resources or to locate essential habitats (e.g., for spawning). Inherent challenges exist with the assessment of fish populations because they are moving targets. We submit that quantifying and describing the s...

In this study, animal-borne telemetry with temperature sensors was coupled with extensive habitat temperature monitoring in a dimictic reservoir, to test the following hypotheses: behavioural thermoregulation occurs throughout the year and temperature selection varies on a diel and seasonal basis, in a winter-specialist diel-migrating fish. Burbot...

In North America, burbot Lota lota (L.), interactions with hydropower are common, southern burbot populations are endangered and hydropower has been implicated in the decline. Thus, the objectives of this review were to identify threats and benefits of hydropower to riverine and reservoir dwelling burbot, assess overall impacts and identify key res...

Animal movement occurs as a function of many factors including changing environmental conditions (e.g., seasonality) and the internal state (e.g., phenotypic traits) of the focal organism. Identifying how these factors interact can reveal behavioral patterns that would otherwise go undiscovered. Given a large sample size of individuals (n = 187), w...

The reproductive migration of anadromous salmonids through estuarine waters is one of the most challenging stages of their life cycle, yet little is known about the environmental and physiological conditions that influence migratory behaviour. We captured, sampled tissues, tagged and released 365 sockeye salmon (Oncorhynchus nerka) homing through i...

The trade-off between remaining stationary and being active has consequences for the survival and growth of fishes. Recent advancements in telemetry tools have enabled researchers to assess activity patterns of free-swimming fishes using tri-axial acceleration-sensing acoustic transmitters. This study describes the summer activity patterns of muske...

Quantifying fine-scale locomotor behaviours associated with different activities is challenging for free-swimming fish. Biologging and biotelemetry tools can help address this problem. An open channel flume was used to generate volitional swimming speed (Us) estimates of cultured lake sturgeon (Acipenser fulvescens Rafinesque, 1817) and these were...

Although personality has been documented in numerous animals and characters, research into personality-dependent spatial ecology has focused on dispersal. Indeed, few authors have investigated the role of other important spatial traits such as home range, movement distance, vertical activity, and site fidelity, and it is not clear whether these beh...

The Amazon basin is home to a large number of migratory fishes whose behavior is still poorly known. Historical fisheries catch data suggest that critical habitats of large migratory catfish are often separated by hundreds of kilometers. We used acoustic (fixed) and radio (fixed and mobile) telemetry to investigate migratory movements of redtail (P...

Fish entrainment through turbine intakes is one of the major issues for operators of hydropower facilities because it causes injury and/or mortality and adversely affects population abundance. Here we used fine-scale acoustic biotelemetry and state-space modeling to investigate behavioural attributes associated with entrainment risk for adult bull...

Heterogeneity in spatial ecology is often observed within fish populations, although few researchers have investigated whether these between-individual differences are temporally consistent and thus represent personality-dependent behaviour. Furthermore, between-individual differences in dispersal and the relationships between dispersal and site fi...

Background: Fish entrainment through turbine intakes is one of the major issues for operators of hydropower facilities because it causes injury and/or mortality and adversely affects population abundance. Entrainment reduction strategies have been developed based on the behavior of downstream migrating fishes, particularly diadromous species. Howev...

Although behaviour and physiology of the reproductive migration of Pacific salmon Oncorhynchus spp. have been studied for the upriver migration, equivalent information for the coastal marine migratory phase has been difficult to obtain. Acoustic acceleration transmitters equipped with pressure sensors provide a tool to study swimming activity and m...

Temperature is recognized as a key factor influencing physiology, behaviour and survival of anadromous salmonids, yet little is known about their thermal experience, nor factors affecting it, during marine homeward migrations. In 2006 and 2010, approximately 1000 Fraser River sockeye salmon Oncorhynchus nerka were captured and tagged in coastal mar...

We sought to improve the understanding of delayed mortality in migrating sockeye salmon (Oncorhynchus nerka) captured and released in freshwater fisheries. Using biotelemetry, blood physiology, and reflex assessments, we evaluated the relative roles of gill net injury and air exposure and investigated whether using a recovery box improved survival....

Migrating adult sockeye salmon frequently encounter commercial and recreational fishing gear, from which they may be landed, escape or be intentionally released. In this experiment, migratory adult sockeye salmon were exposed to simulated capture–release in fresh water, including 3 min of exhaustive exercise and 60 s of air exposure at three ecolog...

Fish entrainment occurs when individuals are displaced from reservoirs to downstream waters by way of water diversion through turbines or other water release structures. While much effort has been put into quantifying and reducing entrainment of downstream migrating salmonids, considerably less research has focused on fish that are residents in res...

Generating awareness of environmental conservation issues among the public is essential if there is an expectation of them to alter their behaviour, facilitate informed decisions and engage governments or regulatory authorities to take action. There are, however, exceedingly few public engagement success stories related to inland fishes and fisheri...

Diel vertical migration (DVM) in pelagic organisms is typically attributed to bioenergetic gain, foraging opportunity, predator avoidance, and multi-factor hypotheses. While a number of benthic species perform nightly migrations into shallower waters, the function of these DVMs have largely been ignored in benthic fishes. We used depth and temperat...

In aquatic organisms, diel vertical migration (DVM) is typically characterized as ascent at dusk and decent at dawn. Often several hypotheses are required to explain the sensory-mechanisms and ultimate causes of DVM. Currently, most of the research focused at the individual level has identified DVM functions as a response to light, feeding opportun...

Sockeye salmon (Oncorhynchus nerka) is one of the most iconic and valued species of Pacific salmon. Various studies have examined the potential effects of future climate change on sockeye salmon, but there is currently no synthesis of the documented effects of climate on this species. In this paper, we present a synthesis of 80 peer-reviewed public...

The dynamics of population niches result from the variation in resource use within individuals and also from the variation between individuals. The prevalence of one mechanism or the other leads to competing hypotheses about the major mechanisms underlying the empirical observations of the contraction/expansion dynamics of the trophic niche in natu...

Summary of the first step-down model selection procedure for the capture-recapture analysis. (DOC)

Schematic representation of the study site. (DOC)

Transition probabilities, recapture probabilities, and population size estimates for the harvestman Iporangaia pustulosa. (A) Transition probability estimates between male parental states. Solid diamonds represent estimates for the transition from non-caring to caring states, while filled diamonds represent estimates for the transition from caring...

For fish at temperate latitudes, lake depths offer a range of environmental conditions that can be accessed to optimize physiological processes such as metabolism and maximize species’ and life-stage specific fitness functions. The depths that fish occupy are ecologically relevant, however, only recently have detailed assessments of individual dept...

Diel vertical migration (DVM) is a strategy common amongst freshwater organisms and is thought to be driven by either thermal habitat selection for bioenergetic advantages, foraging habitat optimisation or predator avoidance. While a larval DVM has been reported for burbot, evidence supporting adult burbot DVMs and nocturnal activity patterns are s...

It is often recognized, but seldom addressed, that a quantitative assessment of the cumulative effects, both additive and non-additive, of multiple stressors on fish survival would provide a more realistic representation of the factors that influence fish migration. This review presents a compilation of analytical methods applied to a well-studied...

This paper synthesizes tagging studies to highlight the current state of knowledge concerning the behaviour and survival of anadromous salmonids in the marine environment. Scientific literature was reviewed to quantify the number and type of studies that have investigated behaviour and survival of anadromous forms of Pacific salmon (Oncorhynchus sp...

References for peer-reviewed articles that were incorporated into descriptive review (i.e. numerical results). (DOC)

Boolean search terms used in Web of Science and Aquatic Science and Fisheries Abstracts academic search engines to locate peer-reviewed literature. (DOC)

Recent studies have shown that warm temperatures reduce survival of adult migrating sockeye salmon (Oncorhynchus nerka), but knowledge gaps exist on where high-temperature-related mortality occurs along the migration and whether females and males are differentially impacted by river temperature. In this study, we monitored 437 radio-tagged Fraser R...

Some Pacific salmon populations have been experiencing increasingly warmer river temperatures during their once-in-a-lifetime spawning migration, which has been associated with en route and prespawn mortality. The mechanisms underlying such temperature-mediated mortality are poorly understood. Wild adult pink (Oncorhynchus gorbuscha) and sockeye (O...

To date, the majority of research on fish entrainment in hydropower reservoirs has focused on downstream migrating smolts with comparatively little known about the entrainment vulnerability of adult fish. Given that vulnerability to entrainment is likely to fluctuate with seasonal changes in adult behaviour (e.g., spawning migrations), the first st...

Energetically demanding spawning migrations of sockeye salmon (Oncorhynchus nerka) can have a negative influence on maternal condition. Individual-based research has focused on examining the impact of adverse spawning migration conditions on female survival, reproductive development (e.g. egg size, number, spawn timing, retention), egg viability, a...

Mean summer water temperatures in the Fraser River (British Columbia, Canada) have increased by ~1.5-2.0oC since the 1950’s. In recent years, record high river temperatures during spawning migrations of Fraser River sockeye salmon (Oncorhynchus nerka) have been associated with high mortality events, raising concerns about long-term viability of the...

For the first time we present marine temperature data recovered from approximately 80 individual sockeye salmon that were tagged with thermal data loggers in the Johnstone Strait, British Columbia in 2006 and 2010. In both years, thermal data loggers were attached to radio tags that registered on receivers as fish migrated into the Fraser River and...

Mean summer water temperatures in the Fraser River (British Columbia, Canada) have increased by ∼1.5 °C since the 1950s. In recent years, record high river temperatures during spawning migrations of Fraser River sockeye salmon (Oncorhynchus nerka) have been associated with high mortality events, raising concerns about long-term viability of the num...

Differences in growth patterns between the sexes of the gracile mouse opossum Gracilinanus microtarsus and the consequences for home range size were investigated in a savanna habitat (cerrado) of south-eastern Brazil. A total of 51 juvenile individuals of Gracilinanus microtarsus was monitored using capture–mark–recapture from November 2005 to Augu...

Gracilinanus microtarsus (J. A. Wagner, 1842), called the Brazilian gracile opossum, is a small didelphid that is 1 of 6 species in the genus Gracilinanus. It is a sexually dimorphic, solitary marsupial that has a highly seasonal reproductive pattern. It inhabits Atlantic rain forests and semideciduous forests interspersed in the highly seasonal ce...

Many generalist populations may actually be composed of relatively specialist individuals. This ‘individual specialization’ may have important ecological and evolutionary implications. Although this phenomenon has been documented in more than one hundred taxa, it is still unclear how individuals within a population actually partition resources. Her...

In a study aiming to describe the diet of Micoureus paraguayanus in a southeastern Brazilian Cerrado (savannah-like) remnant, we found young didelphid remains in fecal samples from live-trapped adults. These findings uncovered either events of scavenging on dead young didelphids or infanticide adding to the knowledge on the dietary breadth and beha...

Bourguyia hamata females oviposit almost exclusively inside the rosette formed by the curled leaves of the epiphytic bromeliad Aechmea nudicaulis. We investi- gated whether the architecture of the individual bromeliads influences oviposition site selection by this harvestman species. We collected data on the presence of clutches in- side bromeliads...

The description of patterns of variation in any character system within well-defined species is fundamental for understanding lineage diversification and the identification of geographic units that represent opportunities for sustained evolutionary divergence. In this paper, we analyze intraspecific variation in cranial shape in the Pumpkin Toadlet...