William Twardek

Carleton University · Department of Biology

Assisted migration entails the human assisted movement of individuals to more climatically-suitable areas within or outside of their current species range to help species respond to climate change. To better understand the potential for assisted migration to benefit species threatened by climate change, we conducted an evidence synthesis to map exa...

Modified bite-shortened hooks show promise for enabling easy handling and rapid release of fish captured by recreational anglers, with the potential to reduce injury and stress of released fish. This study investigated whether bite-shortened modified hooks were effective at improving fish welfare relative to more traditional hook configurations. We...

Human-induced climate change is already apparent through warming temperatures, altered precipitation, and greater prevalence of extreme weather events (e.g., droughts and floods) all of which are anticipated to be exacerbated in the foreseeable future. Meanwhile, demand for hydropower generation is expected to increase and future hydropower develop...

Fishways can restore functional connectivity within rivers for migratory fish where barriers compromise connectivity. Providing fish passage is particularly important for semelparous, anadromous species that require access to upriver habitats to successfully reproduce. From 2017 to 2020, we used a combination of acoustic and radio telemetry to inve...

Fish passage science and practice seeks to facilitate the movement of fish around obstacles in their habitat, primarily through the construction of fishways and culverts. Successful implementation of fish passage requires collaboration between groups with very different backgrounds and expertise, including knowledge-producers (scientists who study...

Differences in individual personality are common amongst animals, which can play an ecological and evolutionary role given links to fitness. Personality affects animal life processes and outputs (e.g., behavior, life history, growth, survival, reproduction), and has become a common theme in animal behavioral ecology research. In the present study,...

Movement of fishes in the aquatic realm is fundamental to their ecology and survival. Movement can be driven by a variety of biological, physiological, and environmental factors occurring across all spatial and temporal scales. The intrinsic capacity of movement to impact fish individually (e.g., foraging) with potential knock‐on effects throughout...

Chinook salmon (Oncorhynchus tshawytscha, Walbaum 1792) from the upper Yukon River are highly unique, with some populations migrating nearly 3,000 km to spawning habitat near the northern range limit for the species. We conducted a 4-year study to understand the behaviour of Chinook salmon in the terminal reaches of their migration by tagging salmo...

Freshwater biodiversity is in a state of crisis. The recent development of a global emergency recovery plan to “bend the curve” for freshwater biodiversity lacks the necessary details for implementation in a regional context. Using Canada as an example, we describe a toolbox intended to equip decision-makers and practitioners with evidence-based to...

There are many syntheses on the role of animal behavior in understanding and mitigating conservation threats for wildlife. That body of work has inspired the development of a new discipline called conservation behavior. Yet, the majority of those synthetic papers focus on non-fish taxa such as birds and mammals. Many fish populations are subject to...

Recreational fisheries are diverse in scale, scope, and participation worldwide, constituting an important ecosystem service of marine and freshwater ecosystems. Management of these socio‐ecological systems is challenged by monitoring gaps, stemming from difficulties engaging with participants, biased sampling, and insufficient resources to conduct...

Hydropower production is one of the greatest threats to fluvial ecosystems and freshwater biodiversity. Now that we have entered the Anthropocene, there is an opportunity to reflect on what might constitute a ‘sustainable’ Anthropocene in the context of hydropower and riverine fish populations. Considering elements of existing practices that promot...

Barriers in rivers have the potential to severely decrease functional connectivity between habitats. Failure to pass barriers and reach natal spawning habitat may compromise individual reproductive success, particularly for semelparous, philopatric species that rely on free-flowing rivers to reach natal habitat during their once in a lifetime spawn...

Fish passage structures have been constructed to facilitate fish movement past barriers, though the effectiveness of passage structures is highly variable. Designing fish passage structures that consider the behavioural preferences of fish under different environmental conditions (e.g., light colour, substrate type) has the potential to improve fis...

Group size influences LED light colour and substrate preference of David’s Schizothoracin （Schizothorax davidi): relevance for design of fish passage facilities

• Anadromous Atlantic salmon (Salmo salar) populations have declined across their Southern distributions in North America. While river temperature has been identified as a central factor influencing migration behavior and over-winter survival, little research has addressed the prevalence of infectious agents in wild Atlantic salmon populations. Fur...

American eel (Anguilla rostrata) is considered endangered under the IUCN's red list. Hydropower facilities are considered a significant threat to American eel, impacting both the outmigration of adults and upstream migration of juveniles. To overcome upstream passage issues, juvenile eels may be trapped and transported around barriers as a mitigati...

During spawning, adult Pacific salmonids ( Oncorhynchus spp . ) complete challenging upriver migrations during which energy and oxygen delivery must be partitioned into activities such as locomotion, maturation and spawning behaviours under the constraints of an individual's cardiac capacity. To advance our understanding of cardiac function in free...

Abstract Freshwater biodiversity loss is one of the greatest environmental threats in our changing world. Although declines have been reported extensively in the literature, much less attention has been devoted to solving the freshwater biodiversity crisis relative to other ecosystems. The recently proposed Emergency Recovery Plan for Freshwater Bi...

Technology that is developed for or adopted by the recreational fisheries sector (e.g., anglers and the recreational fishing industry) has led to rapid and dramatic changes in how recreational anglers interact with fisheries resources. From improvements in finding and catching fish to emulating their natural prey and accessing previously inaccessib...

National parks occur in most nations around the globe and tend to have a dual role of protecting natural heritage features while also providing opportunities for the public to interact with natural areas through recreation and leisure. National parks are afforded varying degrees of protection with recreational fishing allowed in some form within th...

The COVID-19 global pandemic and resulting effects on the economy and society (e.g., sheltering-in-place, alterations in transportation, changes in consumer behaviour, loss of employment) have yielded some benefits and risks to biodiversity. Here, we considered the ways the COVID-19 pandemic has influenced (or may influence) freshwater fish biodive...

Widespread declines in migratory fish highlight the need for increased global efforts to raise awareness of their value and abate threats they face. World Fish Migration Day (WFMD), coordinated by the World Fish Migration Foundation, is a biennial global celebration of open rivers and migratory fish achieved through locally organized events with th...

Fish passage facilities are constructed to enable fish to pass anthropogenic barriers such as dams though their efficiency varies across species and location. There are a number of studies that assess the efficiency of fish passage facilities, yet rarely have such assessments been conducted in Asia. We conducted one of the first quantitative assess...

Culturomics is emerging as an important field within science, as a way to measure attitudes and beliefs and their dynamics across time and space via quantitative analysis of digitized data from literature, news, film, social media, and more. Sentiment analysis is a culturomics tool that, within the last decade, has provided a means to quantify the...

Length-based harvest restriction is common in fisheries management and can result in a substantial number of fish being released after capture. Science on live release confirms that the practice allows individuals to return to the population and reproduce; however, little is known about how handling practices influence mortality or the sub-lethal p...

Anadromous fishes such as steelhead trout, Oncorhynchus mykiss, are exposed to a suite of infectious agents and migratory challenges during their freshwater migrations. We assessed infectious agent load and richness and immune system gene expression in gill tissue of Bulkley River (British Columbia, CA) steelhead captured at and upstream of a migra...

Understanding the human dimensions of recreational fisheries is critical to the development of effective fisheries management regulations. This study aimed to characterize Australian shortfin mako shark (Isurus oxyrinchus) anglers in terms of their gear use, perceptions on circle hooks, perceptions on sharks and shark conservation, and attitudes to...

Shoaling is an evolved behavior in fishes that has several adaptive advantages, including allowing individuals to avoid predation through risk dilution. However, factors such as size disparity and the presence of heterospecifics may influence the behavior of individual fish within shoals following exposure to elevated predation risk. Using bluegill...

We investigated the response of Atlantic salmon (Salmo salar) to capture and handling stressors by analyzing fine-scale locomotor activity using accelerometer data loggers and broader-scale movements by tracking migration with radiotelemetry. Half the sample population was exposed to experimental exercise and air exposure and released with a contro...

Recreational fisheries that use rod and reel (i.e., angling) operate around the globe in diverse freshwater and marine habitats, targeting many different gamefish species and engaging at least 220 million participants. The motivations for fishing vary extensively; whether anglers engage in catch‐and‐release or are harvest‐oriented, there is strong...

Steelhead Oncorhynchus mykiss are captured and released during spawning migrations by the commercial, subsistence (Indigenous), and recreational fishing sectors, though the consequences of these fisheries interactions on Steelhead migration are poorly understood. This study evaluated injury, reflex impairment, behaviour, and survival of released wi...

Steelhead, the anadromous form of rainbow trout (Oncorhynchus mykiss), is one of the most coveted recreationally targeted salmonids worldwide, and catch-and-release (C&R) is commonly used as a conservation strategy to protect wild stocks. Nevertheless, little research has examined how wild steelhead respond to capture and handling. During a summer-...

Bycatch in fisheries is a well-explored topic, although less so in recreational fisheries. We encountered frequent bycatch of Mudpuppy (Necturus maculosus), a neotenic aquatic salamander that is active in winter, in passively baited ice-fishing gear targetting teleost fishes. We noted hook location in Mudpuppies captured by two hook types: J-hooks...

Recreational fishing is a popular activity in aquatic ecosystems around the globe using a variety of gears including rod and line and to a lesser extent handlines, spears, bow and arrow, traps and nets. Similar to the propensity to engage in voluntary catch-and-release, the propensity to harvest fishes strongly varies among cultures, locations, spe...

Natural resource agencies have developed catch‐and‐release regulations for Walleyes Sander vitreus of prohibited size and number to reduce mortality in many recreational fisheries. The efficacy of such regulations is contingent upon the released fish surviving, but survival data on Walleyes captured by ice‐angling are lacking. We estimated the surv...

A new geological epoch, the "Anthropocene", has been defined as the period in which humans have had substantial geological and ecological influence on the planet. A positive future for this epoch can be referred to as the "good Anthropocene" and would involve effective management strategies and changes in human behavior that promote the sustainabil...

Humans have created a strong relationship with cats and dogs by domesticating them. Whether owned by a human or living feral, modern domestic cats and dogs interact extensively with people and the environment. The negative interactions between these domesticated animals and wildlife have been discussed in several reviews, but few reports have provi...

Fish are commonly sedated to render them immobile and thus easier to handle for research, veterinary, and aquaculture practices. Since sedation itself imposes a significant challenge on the targeted fish, the selection of sedation methods that minimize physiological and behavioral disturbance and recovery time is essential. Two popular sedation met...

Executive Summary Ice-fishing for Walleye is a popular recreational activity on Lake Nipissing, Ontario. To increase escapement of Walleye in the fishery, the Ontario Ministry of Natural Resources and Forestry has mandated catch-and-release (CnR) regulations for Walleye of prohibited size (i.e. slot limit) or number (i.e. quota or bag limit). Since...

Breeding site fidelity has evolved in many vertebrate taxa, suggesting both that site selection has an important influence on fitness potential and that the decision to reuse a nesting site is related to the individual’s prior nesting success at that location. For a species that provides parental care, such as the Largemouth Bass Micropterus salmoi...

The objective of catch-and-release angling is for the fish to survive with minimal fitness consequences. However, fish survival can be compromised by a number of factors, especially anatomical hooking location. To evaluate whether hook type or bait influence hooking outcomes, we tested different combinations of hook (treble or single siwash hooks)...