ObjectiveThe Fraser River in British Columbia, Canada, historically supported productive Indigenous, recreational, and commercial fisheries for Eulachon Thaleichthys pacificus. Although Eulachon spend most of their lives in the marine environment, they spawn in freshwater and it is hypothesized that habitat degradation in the Fraser River has contributed to population decline. A greater understanding of Eulachon life history strategies is necessary to develop species recovery strategies. The purpose of this study was to provide insight into population demographics, migration timing, residence time, travel speed and distance, and movement patterns of Eulachon traveling in the Fraser River by conducting index netting and acoustic telemetry.MethodsIn total, 244 Eulachon were acoustically tagged at the mouth of the Fraser River, and their movements were monitored using acoustic receivers in the lowermost 70 km of the Fraser River and in the Pitt River (a tributary to the Fraser River) over a 2-year period.ResultTagged Eulachon displayed heterogeneous movement behaviors and a protracted migration period between February and May. Eulachon index gill netting revealed three discrete migration groups matching traditional ecological knowledge from Indigenous knowledge holders. There were shifts in population demographics, with sex ratios changing from predominately males to females throughout the migration. Residence time within the estuarine salt wedge and river was short. Upstream travel speeds varied significantly between sexes and slowed as fish traveled upstream.ConclusionOverall, Eulachon travel speeds, travel distances, and residence times, along with size and sex effects, provided insights into movement patterns. These results will increase our understanding of sex-specific risks related to instream disturbance, harvest, and predation and will inform management decisions regarding protection of critical habitats. The observed patterns highlight the need for stock assessment methods to consider all discrete migration groups and will assist in prioritizing species recovery efforts.

Similar to many small, secretive snakes, the natural history and population biology of Sharp-tailed Snakes are poorly known. Information on habitat use and patterns of abundance are particularly important for management and recovery of this species listed as endangered in Canada. We surveyed for snakes from October 2010 to March 2019 using a microhabitat-based array of 162 artificial cover-object stations. The surveys (236 array checks) resulted in 177 detections of Sharp-tailed Snakes, representing 106 individuals identified through pattern mapping. Body size (snout-vent length) of the snakes ranged from 82 mm to 261 mm, and most (65.1%) were adults >180 mm. The dispersion of snakes among sampling stations was aggregated over time with 42 stations used by one to 15 individuals over the course of the study, including three “hot spots” used by over ten individuals; these sites represented hibernation and possibly also egg-laying sites. Most detections were on the warmer west and south slopes of the hill and were correlated with the presence of talus but not with other habitat attributes examined. The population sampled by the array was estimated to consist of a mean of 128 snakes (6.04/ha) in 2011 and 80 (3.80/ha) in 2018 with mean annual survival rate of 52.9%. We suggest focusing survey efforts on stable talus patches with south- and west-facing aspects both to locate the species at new sites and to identify important habitats at known sites.

In addition to regulating sex, size, and season of harvest, resource managers can implement spatial fishery closures as a management tool to protect Dungeness crab populations. Yet, we have little understanding of the role that spatial closures play in conserving crab populations, especially in fisheries management zones that are subject to intensive harvest. The primary purpose of this study was to evaluate the biological effectiveness of a crab closure area adjacent to an intensive fishery, by examining relative abundance, population demographics, and seasonal movement patterns within and outside of a closure area. Relative abundance and population demographics were assessed weekly from August to October, using standardized trap lines distributed at four locations, stratified by treatment (inside versus outside of closure area) and water depth. To obtain individual male crab movement data within and outside of the closure area, mobile acoustic tracking surveys were conducted one to three times per week in the autumn and winter. Male crabs were larger and in greater abundance inside the closure area than outside. The overall trend in male crab movement was southwest towards deeper water during autumn and winter. Our research supports the hypothesis that fisheries decrease the abundance and size of an exploited species, but closure areas may reduce these effects. Based on the observed seasonal movement patterns of crabs, it appeared that the closure area provided a temporary refuge from harvest. Resource managers should consider seasonal movement patterns, habitat use, and quality of available habitat when selecting closure area boundaries.

Repeatable individual differences often account for large proportions of intraspecific variation in animal movements. However, meta-population models have continued to rely on single species-level and season-specific species-level means for movement prediction. Here, we test the hypothesis that repeatable individual differences can account for a similar proportion of movement distance variation as species differences. We used radio telemetry to generate repeated measures of movement from 504 hetero-specific fish. We tracked 5 large bodied fish species (Salvelinus confluentus, Oncorhynchus mykiss, Prosopium williamsoni, Thymallus arcticus, and Sander vitreus) in the upper reaches of the Peace River, British Columbia, Canada, over 8 years. We applied a hierarchical framework to partition repeatability of movement distances at the intra- and interspecific biological levels, and among short-term (within-season) and long-term (across seasons and years) temporal levels. Our results show that long-term movement distance repeatability was higher at the intraspecific level than at the interspecific level, demonstrating that animal personality can account for more variation in movement than species differences. These findings provide a novel, community level demonstration of the importance of individual variation, highlighting the predictive gains associated with a shift in the focus of spatial ecology, away from species mean and seasonal species-level mean predictive approaches, towards a spatial behavioral types-based predictive approach.

To better understand the mechanisms that lead to marine mortality of homing adult sockeye salmon (Oncorhynchus nerka), gill and blood biopsies were used in combination with biotelemetry to demonstrate how survival to freshwater entry is related to gene expression and physiological indices of stress. Microarray analysis of gene expression indicated multiple biological processes, including immune and stress responses, protein biosynthesis, and metabolism. Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) analysis indicated fish with upregulation of genes related to stress and infection had higher marine survival compared with fish without this genomic signature. We proposed that higher marine survival of potentially stressed and immune compromised fish can be explained by stressed and infected fish being highly motivated to enter fresh water, leading to enhanced marine survival. However, once in a river, stressed and immune compromised fish could suffer higher mortality because of premature river entry. Overall, this study supports the idea that infection and stress are important biological processes influencing behaviour and fate of sockeye salmon during homing migrations.

AbstractDetails of the spatial ecology of White Sturgeon Acipenser transmontanus in the lower Fraser River, British Columbia, are needed for habitat conservation, assessments of impacts from spatially delimited threats, and refinement of abundance estimation methods. The abundance of threatened lower Fraser River White Sturgeon is assessed annually using a Bayesian, closed-population, mark–recapture model. If individuals make prolonged departures from the lower Fraser River, either into marine waters or a tributary, the validity of the model’s assumed closed population is questionable. There is also concern that fish might move far enough to be exposed to harvest in Puget Sound, Washington. From 2008 to 2012, White Sturgeon of various sizes were acoustically tagged in the Pitt River (n = 58) and in the lower reaches of the Fraser River (near Douglas Island, n = 52) to determine the timing, rate, and spatial extent of movements. Movements were monitored using acoustic receivers at 17 locations in the lower...

Variable-retention (VR) logging practices provide an alternative to clearcutting, but much uncertainty exists on their effectiveness in maintaining biodiversity. We compared patterns of abundance of terrestrial gastropods in areas subjected to either clearcutting or VR treatments, in relation to an uncut control at six experimental sites in coastal British Columbia before and 2-4 years after logging. Gastropods sensitive to the logging treatments in most comparisons included Haplotrema vancouverense, Pristiloma stearnsii and P. lansingi (as a group), and Striatura pugetensis. Several generalist species showed no response to the treatments, and the abundance of two species (Punctum randolphii and Vespericola columbianus) increased in some logged treatments relative to the control. At sites where trees were retained in small groups (0.2-0.5 ha), the abundance of four species was depressed when compared to the control and pre-logging values. No differences among retention levels of 10%, 20%, and 30% were found. At a site where trees were retained in groups of different sizes, large groups (0.8-1.2 ha) were more effective in supporting sensitive species than were small groups (< 0.2 and 0.2-0.5 ha) and clearcuts. At a site where dispersed trees were retained, none of the logged treatments were equivalent to the control. No consistent patterns of higher abundance in the 30% retention level than in the 5% and 10% levels were found. The results contribute to the growing body of information on the complexity of responses of forest floor organisms to habitat modification by logging.

Following their first detection in Newfoundland in 2007, populations of invasive European green crabs Carcinus maenas (Linnaeus, 1758) have increased and spread throughout eelgrass Zostera marina meadows. Green crabs can reduce eelgrass biomass by damaging rhizomes and plant shoots when burrowing for shelter and digging for prey. Empirically demonstrating large spatial-scale impacts of green crabs on eelgrass and subsequent cascading effects on the ecosystem has proven difficult because of the general absence of effective baseline studies prior to an invasion of green crabs. We conducted surveys in Placentia and Bonavista bays, Newfoundland (20 sites) to compare eelgrass and associated fish communities before and after an invasion of green crabs. We analyzed eelgrass surveys from 1998 and 1999 (before green crab) and again in 2012 (after green crab) using a Before-After-Control-Impact (BACI) study design in order to isolate effects of crab-induced eelgrass loss from effects independent of green crabs. Underwater video sampling evaluated eelgrass change over time and indicated a 50% decline in eelgrass percent cover since 1998 at sites with green crabs, and eelgrass declines up to 100% at sites with highest abundances and longest established presence of green crabs. Beach seining showed a sharp decline in abundance and biomass of fish (similar to 10-fold between sites with and without green crabs) and indicated changes in fish community structure after green crab arrival at a site. Our results suggest cascading effects on fish communities and substantial potential impacts in coastal ecosystems occur following green crab invasion.

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 inner coastal waters towards the Fraser River, British Columbia, Canada. Biotelemetry was used to assess the behaviour of individual sockeye salmon approaching estuarine waters and at river entry, which were related to both fish physiological condition at release and to prevailing environmental conditions. Sockeye salmon tended to stay close to the shore, migrated during the day, and movements were related to tide. Sockeye salmon migration rate was linked to wind-induced currents, salinity and an individual's physiological state, but these factors were specific to location and stock. We propose that wind-induced currents exposed sockeye salmon entering the estuary to stronger olfactory cues associated with Fraser River water, which in turn resulted in faster migration rates presumably due to either an increased ability for olfactory navigation and/or advanced reproductive schedule through a neuroendocrine response to olfactory cues. However, once the migration had progressed further into more concentrated freshwater of the river plume, sockeye salmon presumably used wind-induced currents to aid in movements towards the river, which may be associated with energy conservation. Results from this study improve our biological understanding of the movements of Fraser River sockeye salmon and are also broadly relevant to other anadromous salmonids homing in marine environments.

We used biotelemetry and human dimensions surveys to explore potential solutions to migration mortality of an endangered population of coho salmon caught as bycatch in an aboriginal beach seine fishery. From 2009 to 2011, 182 wild coho salmon caught as bycatch in the lower Fraser River (Canada) were radio-tagged and tracked as they attempted to complete their migrations to natal spawning areas over 300 km upstream. Failure to survive to reach terminal radio receiving stations averaged 39% over three years. This mortality estimate is low compared to those obtained from telemetry studies on other salmon fisheries in the Fraser River. However, this value is markedly higher than the mortality estimate currently used to manage the fishery's impact. It is also in contrast to the perceptions of the majority of aboriginal fishers, who did not think survival of coho salmon is affected by capture and release from their fishery. Increased probability of survival was associated with lower reflex impairment, which is consistent with previous findings. Reflex impairment was positively correlated with entanglement time, suggesting that greater efforts by the fishers to release bycatch from their nets quickly would minimize post-release mortality. Survey responses by aboriginal fishers also suggested that they are receptive to employing new bycatch handling methods if they are shown to increase post-release survival. However, attempts to facilitate revival of a subset of captured fish using cylindrical in-river recovery bags did not improve migration success. Fisheries managers could use the new information from this study to better quantify impacts and evaluate different harvest options. Since aboriginal fishers were receptive to using alternate handling methods, efforts to improve knowledge on minimizing reflex impairment through reductions in handling time could help increase bycatch survival. Such a direct integration of social science and applied ecology is a novel approach to understanding conservation issues that can better inform meaningful actions to promote species recovery.

Sea-chests, recesses built into the hull of a vessel, have been recently identified as hotspots for fouling organisms. In this study, we examined the types and abundances of taxa found in sea-chests of commercial vessels, and investigated whether vessel specifications and voyage histories influenced the nature and extent of sea-chest fouling. Eighty-two sea-chests were sampled from 39 commercial vessels while in dry dock on the West or East Coast of Canada. Overall, 80% of the vessels showed evidence of sea-chest fouling, and 46% harboured at least one non-indigenous species. In total, 299 unique taxa were recorded, including a number of non-indigenous and cryptogenic organisms that collectively made up 20.5% and 14.4% of the taxa sampled from West and East Coast vessels, respectively. Additional results suggested that in-service period (i.e., duration since last sea-chest cleaning) and vessel origin (i.e., domestic versus international) may, in part, determine the nature and extent of sea-chest fouling. By contrast, vessel size and port duration were unable to explain taxonomic richness or abundance of fouling organisms in sea-chests. Taken together, these findings highlight the role of sea-chests as an important vector responsible for the introduction and spread of a variety of taxa, including aquatic invasive species, but also suggest that the factors that influence sea-chest fouling in commercial vessels are complex. Further research, aimed at better understanding the determinants of sea-chest fouling and the efficacy of anti-fouling systems, would help further refine management strategies and reduce the risks associated with sea-chest fouling.

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 marine waters, similar to 215 km from the river mouth, during their spawning migration. Individual salmon were blood sampled, gastrically implanted with temperature loggers fixed to radio or acoustic tags, and released. We recovered 50 loggers from freshwater locales containing 14690 hourly temperature readings. Mixed-effects models were used to characterize marine thermal experience, and examine the association of thermal experience with initial physiological status as well as oceanographic and meteorological conditions. Sockeye salmon thermal experience was highly variable (8.4 degrees C to 20.5 degrees C), and we detected opposite diel patterns between study years that could be associated with moon phase, behavioural thermoregulation, olfactory/celestial navigation or predator avoidance. We were unable to find any relationships between thermal experience and environmental conditions or fish physiological state. Nonetheless, we found that the greatest variability in thermal experience was attributed to within-individual variation, suggesting that environmental and physiological variables need to be examined at different temporal and spatial scales, and/or additional environmental and physiological variables need to be assessed. Overall, the factors associated with the thermal experience of homing sockeye salmon in coastal marine environments are more complex than previously thought, and multiple year studies are needed before generalizing behavioural patterns observed from single year studies.

We evaluate the utility of an inexpensive, portable recovery bag designed to facilitate recovery of fish from capture stress by combining physiological assays, biotelemetry, and social science surveys. Adult migrating Pacific salmon (Oncorhynchus spp.) were used as a model, since some of their populations are threatened. While catch-and-release is common, there is a need to ensure that it is sustainable. A social science survey revealed that anglers generally have positive attitudes towards recovery bag use, particularly if research identifies that such techniques could be effective. Physiological assays on pink salmon (Oncorhynchus gorbuscha) revealed benefits of both high- and low-velocity recovery, but high velocity was most effective with reduced plasma cortisol concentrations and similar plasma sodium and chloride concentrations as those found in controls at all recovery durations. A biotelemetry study on sockeye salmon (Oncorhynchus nerka) captured by anglers and stressed by air exposure then placed in recovery bags had 20% higher, but not significantly different, survival than no-recovery salmon. The integration of natural science and social science provides an important step forward in developing methods for promoting recovery of fish from capture.

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 River sockeye salmon and used capture–mark–recapture modelling approaches to investigate whether river thermal conditions differentially influence (i) spatial patterns of survival along a 413-km stretch of migration and (ii) survival of the sexes. Regardless of water temperature, survival decreased in the river section containing the most hydraulically difficult passages of the migration. However, when water temperature was warm (19 °C), survival decreased even further in the final 186 km of the migration prior to reaching the spawning grounds, particularly in females. Female and male survival differed but only when they experienced warm river temperatures. Under such conditions, the overall freshwater migration survival of males was 1.6 times higher (0.79 ± 0.09 standard error, SE) than that of females (0.50 ± 0.11 SE). As maturing female sockeye salmon maintain higher levels of plasma cortisol compared with males, we suspect that females could be immuno-compromised and thus less resistant to pathogens whose rates of development are accelerated by warm temperatures.

Summary 1. Effective management of fish and wildlife populations benefits from an understanding of the effects of stressors on individual physiology. While physiological knowledge can provide a mechanistic understanding of organismal responses, its applied utility is limited because it cannot easily be used by stakeholders. 2. Reflex action mortality predictors (RAMP) is a method that involves checking for the presence or absence of natural animal reflexes to generate a condition (RAMP) score in response to stressors and to predict fate. The method has previously been validated with fishes in artificial laboratoryand field-based holding studies as a responsive measure of fisheries capture stress and a predictor of delayed mortality, but has not been evaluated in the wild. 3. We used radio telemetry to monitor migration success of 50 endangered coho salmon Oncorhynchus kisutch following incidental capture in an aboriginal beach seine fishery in the lower Fraser River (Canada). RAMP was used to measure the condition of fish at release and to predict migration success following capture. Biopsy of an additional 43 coho profiled physiological condition at time of release. 4. Individuals with greater reflex impairment (higher RAMP scores) at release experienced significantly higher rates of migration failure. RAMP scores were also significantly correlated with fishery handling time. Plasma variables showed that captured coho had experienced physiological stress characteristic of exhaustive exercise and hypoxia, with significantly elevated cortisol and lactate values for fish entangled longer in fishing gear. 5. Synthesis and applications. This is the first validation of RAMP in a wild setting. Based on our findings, fishers could use the method and make adjustments in fishing behaviour in real-time to improve fish condition and reduce the mortality of bycatch, and conservation practitioners could monitor animal condition and identify problems that deserve management attention. RAMP is an easy, rapid and inexpensive approach to predicting mortality and measuring vitality and performed better than traditional physiological tools that cannot easily be used by stakeholders.

Few studies have examined the effects of fisheries capture on wild fish, particularly in the context of evaluating the sustainability of capture and release methods for Pacific salmon (Oncorhynchus spp.) during upriver migration. This study examined the physiological condition, post-release behaviour and survival of adult migrating sockeye salmon (O. nerka) in the Fraser River, British Columbia, Canada. Fish were captured by either beach seine or angling and released immediately, or were captured by angling and released following a 24-h recovery period in a net pen. Before release, all salmon were biopsied or tagged with radio telemetry transmitters. Capture by either angling or beach seine with immediate release resulted in >95% survival 24h after release, whereas net pen recovery after angling resulted in ∼80% survival. This differential in survival was similarly expressed in the percentage of released fish reaching natal sub-watersheds, with 52.2% and 36.3% of fish immediately released by beach seine and angling reaching natal sub-watersheds, respectively, compared with 2.9% of fish released after angling and net pen recovery. Blood plasma stress indices reflected the 10-fold difference in survival, with a ∼4-fold higher plasma cortisol, a ∼2-fold higher plasma glucose and significantly depressed plasma ions and osmolality relative to fish sampled upon capture. Plasma lactate did not differ among groups. Collectively, these results suggest that a 24h recovery in net pen following angling failed to promote post-release survival experienced with immediate release after angling or beach seining.

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.

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 (ΔT), yet individuals maintained a ΔT of –1 °C or cooler for only 5% of their migration through the study region. There were moderate mean deviations of ΔT in two segments that are known to contain thermally stratified waters. In one of the study segments with the greatest ΔT, mean body temperatures decreased as river temperatures increased and ΔT 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 ΔT 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 sockeye stocks that are predicted to encounter increasing peak summer river temperatures in the coming decades.