Kyle C. Hanson

Developing a Mechanistic Understanding of Fish Migrations by Linking Telemetry with Physiology, Behavior, Genomics and Experimental Biology: An Interdisciplinary Case Study on Adult Fraser River Sockeye Salmon

Abstract Fish migration represents one of the most complex and intriguing biological phenomena in the animal kingdom. How do fish migrate such vast distances? What are the costs and benefits of migration? Some of these fundamental questions have been addressed through the use of telemetry. However, telemetry alone has not and will not yield a complete understanding of the migration biology of fish a or provide solutions to problems such as identifying physical barriers to migration or understanding potential impacts of climate change. Telemetry can be coupled with other tools and techniques to yield new insights into animal biology. Using Fraser River sockeye salmon (Oncorhynchus nerka) as a model, we summarize the advances that we have made in understanding salmonid migration biology through the integration of disciplines (i.e., interdisciplinary research) including physiology, behavior, functional genomics, and experimental biology. We also discuss opportunities for using large-scale telemetry arrays an...

Mechanisms Influencing the Timing and Success of Reproductive Migration in a Capital Breeding Semelparous Fish Species, the Sockeye Salmon

Two populations of homing sockeye salmon (Oncorhynchus nerka; Adams and Chilko) were intercepted in the marine approaches around the northern and southern ends of Vancouver Island (British Columbia, Canada) en route to a natal river. More than 500 salmon were nonlethally biopsied for blood plasma, gill filament tips, and gross somatic energy (GSE) and were released with either acoustic or radio transmitters. At the time of capture, GSE, body length, and circulating testosterone ([T]) differed between populations, differences that reflected known life‐history variations. Within‐population analyses showed that in Adams sockeye salmon, plasma glucose ([glu]), lactate ([lactate]), and ion concentrations were higher in the northern approach than in the southern approach, suggesting that the former was more stressful. GSE, [T], and gill Na+,K+‐ATPase activities also differed between the two locales, and each varied significantly with Julian date, suggesting seasonality. Despite these relative geographic differences, the timing of river entry and the ability to reach spawning areas were strongly correlated with energetic, reproductive, and osmoregulatory state. Salmon that delayed river entry and reached spawning areas had relatively high GSE and low [T] and gill ATPase. In contrast, salmon that entered the river directly but that ultimately failed to reach spawning areas had lower GSE and higher [T] and gill ATPase, and they also swam at significantly faster rates (failed fish ∼20.0 km d−1 vs. successful fish ∼15.5 km d−1). Physiologically, salmon that did not enter the river at all but that presumably died in the marine environment exhibited high stress (plasma [glu] and [lactate]) and ionoregulatory measures (plasma [Na+], [Cl−], osmolality).

Use of CDMA Acoustic Telemetry to Document 3-D Positions of Fish: Relevance to the Design and Monitoring of Aquatic Protected Areas

Knowledge of animal spatial ecology is essential for the design and siting of proposed aquatic protected areas (APAs), as well as the assessment and monitoring of existing ones. Acoustic telemetry is one of the primary tools for the assessment of animal movements in aquatic systems through either manual tracking or the establishment of fixed receiving stations. Recent technological developments in code division multiple access (CDMA) acoustic telemetry now enable the simultaneous real-time monitoring of numerous individual fish at fine time scales providing APA researchers with a robust new tool. Fish can be positioned in three-dimensions with sub-meter accuracy in both deep and shallow waters. Here, we describe a whole-lake environmental observatory that includes a 13-hydrophone acoustic telemetry array that has been used to monitor the position of 22 tagged fish at 15 sec intervals. Although we use a freshwater fish and environment as a case study, this telemetry system is equally useful for marine environments including under-ice. We evaluate the applicability of CDMA MAP technology to address pressing questions in applied APA research. The CDMA MAP system provides the flexibility to collect information at multiple spatialtemporal scales, responding to the varied levels of detail and precision required for different applications in APA research. When combined with the suite of other telemetry and monitoring approaches available, CDMA MAP technology will enable researchers to document the spatial ecology essential for improving APA science. Furthermore, because numerous animals from different trophic levels can be tracked in real time, CDMA MAP technology will also aid in our understanding of complex community-level dynamics consistent with the shift towards ecosystem-based APA management.

Individual variation in migration speed of upriver-migrating sockeye salmon in the Fraser River in relation to their physiological and energetic status at marine approach.

Little research has examined individual variation in migration speeds of Pacific salmon (Oncorhynchus spp.) in natural river systems or attempted to link migratory behavior with physiological and energetic status on a large spatial scale in the wild. As a model, we used three stocks of summer‐run sockeye salmon (Oncorhynchus nerka) from the Fraser River watershed, British Columbia, to test the hypothesis that individual variation in migration speed is determined by a combination of environmental factors (i.e., water temperature), intrinsic biological differences (sex and population), and physiological and energetic condition. Before the freshwater portion of the migration, sockeye salmon (Quesnel, Chilcotin, and Nechako stock complexes) were captured in Johnstone Strait (∼215 km from river entry), gastrically implanted with radio transmitters, and sampled for blood, gill tissue, and energetic status before release. Analyses focused solely on individuals that successfully reached natal subwatersheds. Migration speeds were assessed by an extensive radiotelemetry array. Individuals from the stock complex that migrated the longest distance (Nechako) traveled at speeds slower than those of other stock complexes. Females traveled slower than males. An elevated energetic status of fish in the ocean was negatively correlated with migration speed in most river segments. During the transition from the ocean to the river, migration speed was negatively correlated with mean maximum water temperature; however, for the majority of river segments, it was positively correlated with migration speed. Physiological status measured in the ocean did not explain among‐individual variability in river migration speeds. Collectively, these findings suggest that there could be extensive variation in migration behavior among individuals, sexes, and populations and that physiological condition in the ocean explained little of this variation relative to in‐river environmental conditions and energetic status. Interestingly, individual fish generally retained their rank in swimming speed across different segments, except when transiting a challenging canyon midway during the migration.

Physiology, Behavior, and Survival of Angled and Air-Exposed Largemouth Bass

Abstract Catch-and-release practices are common in recreational fisheries, yet little is known about the behavior, physiology, and ultimate fate of released fish. We used a combination of radiotelemetry (external attachment) and nonlethal blood sampling (i.e., the blood concentrations of lactate and glucose and plasma concentrations of aspartate aminotransferase (AST), Na+, K+, and Cl−) to assess the relationship between the prerelease physiological status and postrelease behavior and mortality of largemouth bass Micropterus salmoides. The experiments were conducted at two temperatures: approximately 15°C and 21°C. Immediately after capture by standard angling techniques, largemouth bass were exposed to air for 0 to 15 min to assess the consequences of air exposure at two moderate water temperatures. Fish exposed to air for long periods (approximately 10 min or more) had significantly higher concentrations of blood glucose 30 min after air exposure and took significantly longer to regain equilibrium than ...

Locomotory activity and depth distribution of adult great barracuda (Sphyraena barracuda) in Bahamian coastal habitats determined using acceleration and pressure biotelemetry transmitters

Documenting free-swimming fish in their natural environment using acoustic transmitters equipped with acceleration and pressure sensors may contribute to knowledge of locomotory behaviour for a variety of aquatic species. Previously, collection of acceleration data has been limited to archival loggers, necessitating retrieval of the devices; however, recent advances in biotelemetry have allowed for acceleration data to be transmitted to a remote receiver. To illustrate the application of this technology, relative locomotory activity and depth utilisation of adult great barracuda (Sphyraenabarracuda)weremonitoredacrosshabitattypesanddielperiodsusingacoustictransmittersequippedwithtri- axial acceleration and pressure sensors within an acoustic telemetry array (n ¼53 receivers) deployed in The Bahamas. Although there were no differences in acceleration or depth use across habitats or diel periods, there was evidence of movement into shelf habitat during mid-day where they occupied depths410m. Given both the method of calculating the accelerometer output, and that the transmitters were unable to store and transmit large quantities of data, we suggest choosing transmitter settings with a short average delay and high transmission frequency to optimise data quality and resolution. This paper represents one of the first reports of the use of telemetered acceleration values from free-swimming fish.

Limited behavioural thermoregulation by adult upriver-migrating sockeye salmon (Oncorhynchus nerka) in the Lower Fraser River, British Columbia

The objective of this study was to combine radio telemetry with individual thermal loggers to assess the extent to which adult migrating sockeye salmon (Oncorhynchus nerka (Walbaum in Artedi, 1792)) behaviourally thermoregulate during their migration through the Fraser River mainstem, British Columbia. The Fraser mainstem represents a region of the migration route that contains some of the highest mean temperatures encountered by sockeye salmon during their life history. We found that throughout the study area, individual sockeye salmon body temperatures occasionally deviated from ambient temperatures (DT), yet individuals maintained a DT of -1 8C or cooler for only 5% of their migration through the study region. There were moderate mean deviations of DT in two segments that are known to contain thermally stratified waters. In one of the study segments with the greatest DT, mean body temperatures decreased as river temperatures in- creased and DT became increasingly positive with higher river discharge rates, but these relationships were not observed in any of the other study segments. No relationship existed between DT and migration rate. While periodic associations with cool water were evident, mean body temperatures were not significantly different than mean river temperatures throughout the lower Fraser mainstem. This finding raises further conservation concerns for vulnerable Fraser River sock- eye stocks that are predicted to encounter increasing peak summer river temperatures in the coming decades.

Physiological condition differentially affects the behavior and survival of two populations of sockeye salmon during their freshwater spawning migration.

Recently, a segment of the Adams‐Shuswap sockeye salmon (Oncorhynchus nerka) population initiated freshwater migration several weeks earlier than historically recorded, resulting in high mortality rates. The comigrating Chilko population maintained their historic river entry timing and did not experience elevated mortality. To test the hypothesis that population‐specific differences in physiological condition would differentially influence behavior and survival when exposed to fisheries capture stress, we physiologically sampled individuals from both populations at the onset of the freshwater phase of their reproductive migration and tracked the remainder of their migrations using radio telemetry. Adams‐Shuswap individuals had slower migration rates and were less likely to reach natal subwatersheds relative to Chilko individuals. Metabolic and osmoregulatory impairment was related to mortality for Adams‐Shuswap individuals but not for Chilko individuals. Similarly, physiological condition correlated with migration rate for Adams‐Shuswap but not Chilko fish. Survival to natal subwatersheds was 1.9 times higher for Chilko relative to Adams‐Shuswap, a result that did not emerge until individuals approached natal subwatersheds several days after the stressor was applied. We conclude that physiological condition differentially affects the behavior and survival of these two populations, which may be a consequence of the early‐entry phenomenon by a segment of the Adams‐Shuswap population.

Long-term effects of surgically implanted telemetry tags on the nutritional physiology and condition of wild freshwater fish.

Little is known about the long-term consequences of surgically implanted telemetry devices on wild fish, as they are rarely recaptured. We used wild largemouth bass Micropterus salmoides as a model to evaluate the long-term impacts of telemetry devices on fish physiology and nutritional condition in a closed freshwater lake where recapture rates were reasonably high. Between 2003 and 2005, 68 fish were surgically implanted with acoustic telemetry devices. Between 2005 and 2008, 17 of the tagged fish were recaptured after carrying a transmitter for 335 to 1402 d. Incision sites were examined, and individuals were non-lethally sampled for blood and measured prior to release. Plasma samples were analysed, and physiological measures of stress (glucose, Na+, Cl-, K+), tissue damage (aspartate aminotransferase), and nutritional status (Ca++, Mg+, phosphorus, total protein, triglycerides, cholesterol) were compared between fish carrying transmitters and temporally- and size-matched controls. Of the 17 recaptured fish, 3 retained at least 1 of the absorbable monofilament sutures and showed localised signs of inflammation and infection despite an elapsed time of 362 d post surgery. Five individuals showed signs of pressure necrosis at the incision site despite the fact that the transmitters averaged only 1.89% (range: 0.84 to 3.59%) of the body mass. There was no difference in any physiological parameter measured between the 2 groups, or within the telemetered fish, in relation to days since tagging or condition of the incision site. In summary, transmitter implantation was not correlated with any long-term change in any of the physiological parameters investigated. However, there is opportunity for additional research to optimise surgical techniques, guidelines on transmitter mass to body mass ratios, and choice of suture material to enhance the healing and long-term welfare of tagged fish.

Sexual Variation in Fisheries Research and Management: When Does Sex Matter?

In fish, sex determination is a plastic process regulated by a relatively small number of genes that, in turn, leads to a cascade of organism level effects. In other animal taxa, intersexual variation is widespread and has implications in the realms of morphology, behavior, physiology, and bioenergetics. Although relatively well documented in the literature focusing on mammals, birds, and reptiles, the degree to which sex-specific variation is considered is unknown in fish and fisheries research. We examined the scientific literature to evaluate the important sex-related differences in fish and highlighted why some of these differences are of great biological consequence. Sex-specific differences in morphology included sexual size dimorphism, external traits such as coloration, and internal anatomy such as neuron structure. Behavioral differences between the sexes are often linked to reproduction, but there are some documented differences (i.e., variation in aggression and predator avoidance) that are independent of the reproductive period. The potential for sex-related physiological differences are relatively unexplored for fish, although there is strong evidence for disparity in hormone regulation, stress, and immune responses between the sexes. Sex-related variation is also poorly examined in the field of bioenergetics despite the fact that differences in energy requirements and expenditure should and do vary between the sexes. A quantitative literature review of several prominent fisheries journals revealed that sex is often overlooked in fish and fisheries research (between 15 and 44% of articles), which may impair the ability of researchers to detect biologically relevant differences, which in turn can greatly affect management decisions. Although there has been a growing recognition that intra-specific variation (at the population level) is important in fisheries management and research, there is also a need to consider that intersexual diversity exists and is important to understand, conserve, and manage fish and fisheries resources.