Jacqueline M. Chapman

Linking Landscape-Scale Disturbances to Stress and Condition of Fish: Implications for Restoration and Conservation

Humans have dramatically altered landscapes as a result of urban and agricultural development, which has led to decreases in the quality and quantity of habitats for animals. This is particularly the case for freshwater fish that reside in fluvial systems, given that changes to adjacent lands have direct impacts on the structure and function of watersheds. Because choices of habitat have physiological consequences for organisms, animals that occupy sub-optimal habitats may experience increased expenditure of energy or homeostatic overload that can cause negative outcomes for individuals and populations. With the imperiled and threatened status of many freshwater fish, there is a critical need to define relationships between land use, quality of the habitat, and physiological performance for resident fish as an aid to restoration and management. Here, we synthesize existing literature to relate variation in land use at the scale of watersheds to the physiological status of resident fish. This examination revealed that landscape-level disturbances can influence a host of physiological properties of resident fishes, ranging from cellular and genomic levels to the hormonal and whole-animal levels. More importantly, these physiological responses have been integrated into traditional field-based monitoring protocols to provide a mechanistic understanding of how organisms interact with their environment, and to enhance restoration. We also generated a conceptual model that provides a basis for relating landscape-level changes to physiological responses in fish. We conclude that physiological sampling of resident fish has the potential to assess the effects of landscape-scale disturbances on freshwater fish and to enhance restoration and conservation.

Conservation physiology of animal migration

Conservation physiology has great potential to help us understand how migratory animals interact with current and future anthropogenic threats. Migration is inherently challenging such that additional stressors derived from altered environments or interaction with human infrastructure or activities could lead to long-term changes to migratory phenotypes.

Smartphones and Digital Tablets: Emerging Tools for Fisheries Professionals

ABSTRACT Smartphones and digital tablets are used to collect data for agricultural, geographical, and medical research. Science professionals find these devices attractive because they contain many useful hardware accessories (e.g., camera, Global Positioning System [GPS], accelerometer) and the capacity to access and customize software applications (apps). To enhance student learning, some educators are also integrating tablets into curricula for both indoor and outdoor course work. Recently, fisheries professionals have begun using these devices for data collection and public outreach and awareness. With new waterproofing technology, cases, and peripheral adapters, smartphones and digital tablets are continually becoming more relevant for data collection and education in fisheries. Here, we synthesize some of the available information on smartphone and tablet use for data collection and education and explore some current uses and future opportunities for these devices in fisheries. Overall, our objectiv...

Stress in the neighborhood: Tissue glucocorticoids relative to stream quality for five species of fish.

Anthropogenic alterations to terrestrial habitat (e.g., urbanization, deforestation, agriculture) can have a variety of negative effects on watercourses that flow through disturbed landscapes. Currently, the relationship between stream habitat quality and fish condition remains poorly understood. The use of physiological metrics such as glucocorticoids (GCs) provides a useful tool for quantifying these effects by relating the health of resident fishes to stream quality. To date, however, most studies that measure GC levels tend to focus on a single, large-bodied species, rather than evaluating how GCs may be influenced differently between species in a community. In this study, we measured cortisol, the glucocorticoid found in fishes, from fish tissues to quantify effects of habitat degradation on the glucocorticoid function of five species of juvenile and small-bodied stream fish which differ ecologically and phylogenetically. Largemouth bass Micropterus salmoides, brown bullhead Ameiurus nebulosus, white sucker Catostomus commersonii, pumpkinseed Lepomis gibbosus, and logperch Percina caprodes were sampled from a reference and a degraded stream. Upon capture, fish were either euthanized immediately, to quantify baseline stress parameters, or following a standardized stressor, to quantify GC responsiveness. As a result of stream degradation largemouth bass possessed altered baseline GC concentrations and brown bullhead and logperch had altered GC responses to a stressor. White sucker and pumpkinseed did not demonstrate any alteration in baseline or post-stress GC concentrations. Together, our results show that different species residing in identical habitats can demonstrate a variety of responses to environmental stress, highlighting the variation in physiological ability to cope under poor environmental conditions, as well as the difficulty of predicting GC dynamics in wild animals. Understanding the relationships between GC function, habitat quality, and population-level processes will increase the ability of researchers and managers to predict how fish communities and aquatic ecosystems will be shaped by anthropogenic environmental change.

Watershed-scale land use activities influence the physiological condition of stream fish

Land use changes within watersheds can have large effects on stream ecosystems, but the mechanistic basis of those effects remains poorly understood. While changes to population size presumably reflect underlying variation in organismal health and condition, such individual-level metrics are rarely evaluated in the context of ecosystem disturbance. To address this deficiency, we combined physiological sampling with geographic information systems to quantify the effects of land use on physiological indicators of health in largemouth bass. More specifically, we first quantified blood metrics relating to nutrition, oxidative stress, and the glucocorticoid stress response from largemouth bass residing in eight watersheds. We then used Akaike’s information criterion to define relationships between these blood metrics and land cover, including forests, agricultural areas, urban areas, and wetlands. The proportion of forest cover in a watershed was the best predictor of blood metrics representing recent feeding and resistance to oxidative stress, whereas the proportion of wetlands was the best predictor of glucocorticoid function; however, further investigation is needed, as the explanatory power of the models was relatively low. Patterns in energy reserves were not influenced by any land use practices. Interestingly, anthropogenic land use categories, such as urban and agricultural areas, were not the best predictor for any blood metrics. Together, our results indicate that fish health is most related to natural features of a landscape rather than anthropogenic land uses. Furthermore, these findings suggest that physiological methods could supplement traditional population and community assessments to develop a more comprehensive understanding of ecosystem interactions and improve stream management.

Diel variability in fish assemblages in coastal wetlands and tributaries of the St. Lawrence River: a cautionary tale for fisheries monitoring

Both coastal wetlands and tributaries of waterbodies provide important and distinct habitat for freshwater fishes. While diel migration into and out of these systems is known to occur for some species, the resulting changes in fish assemblage composition and dominance are less well understood. To evaluate diel changes in the fish assemblages of a coastal wetland and tributary, fish community surveys were completed at ten locations during the day (noon) and night (midnight) in Cooper’s Marsh, a coastal wetland in the St. Lawrence River, and the Raisin River, a nearby tributary. Catch per unit effort (CPUE) and species richness were highest in the coastal wetland during the night sampling period. Species-specific differences were also apparent with high CPUE of Mimic Shiner in the marsh at night. Differences within the river were less pronounced, suggesting less diel variability in fish assemblage structure, possibly driven by the more constrained nature of fluvial systems. These results contribute to our understanding of diel movement patterns of fishes and the natural diel variability in species assemblages that can occur. These findings also emphasize that when engaged in environmental monitoring and assessment, it is important to consider how diel variation in fish assemblage structure will influence conclusions regarding the biotic components of a given aquatic ecosystem.

Premature alarm on the impacts of climate change on Arctic Char in Lake Hazen

A recent paper by Lehnherr et al. 1 reported on a long-term study of the ecological impacts of climate change in the world’s largest high Arctic lake: Lake Hazen on Canada’s Ellesmere Island. The paper made a convincing case that climate change has had a dramatic and significant impact on the watershed of this important freshwater ecosystem. Some of these changes have clearly impacted the ecology of Lake Hazen. We disagree, however, with the conclusion that such ecological changes have resulted in a significant decline in the condition of Arctic Char (Salvelinus alpinus) from the lake based on the presented data. It is critical to examine the evidence for changes in the condition of Arctic Char given the importance of this species to communities throughout Canada’s Arctic as a valued food resource and because changes to condition could impact its management. Evidence for the impact of climate change on Arctic Char was presented in the form of a time-series (1981–2014; N= 13) of Fulton’s condition factor (Fig. 1), a widely used index of the wellbeing or robustness (i.e., mass relative to length) of individuals or populations of fish2 (for criticisms of the use of condition indices see refs. 3,4). The authors concluded that there was a significant decline in the condition factor of Arctic Char during these years as a result of climate-mediated changes in this ecosystem. We argue, however, that the statistical analysis used to assess the significance of that trend is problematic. We reanalyzed the presented data, which was graciously made available by the authors, using the same analysis as described in the paper. Here, we highlight three issues with the authors’ approach. First, the authors reported a significant quadratic regression model (F2, 1133= 8.47, p= 0.0002 in our analysis), whereas the quadratic term itself was not significant (type 3 F1, 1133= 0.1659, p= 0.684). Second, and more importantly, each individual measurement was treated by Lehnherr et al.1 as an independent data point in the analysis, artificially inflating the reported significance (a problem further accentuated by the unequal sample sizes among years). In the current data set, observations from the same year are likely to be more similar than observations from different years, violating the assumption of independent errors of multiple regression. This aspect of the data should have been treated with an alternative approach such as including a random effect of year or using the annual mean condition factor to test the hypothesis of a decline across years. For instance, the quadratic regression model working on the annual mean condition index is no longer significant (adjusted R2= 0.0075; F1, 10= 1.045; p= 0.387) and neither is a linear regression (adj. R2= 0.047; F1, 11= 1.597; p= 0.233). Our final concern regards the very weak effect size of year. Specifically, there is a weak variation of the mean of Fulton’s condition factor across years (Fig. 1). Even after removing the quadratic term, the slope of the linear regression conducted on either the annual means of condition factor or on the individual fish is −0.002. Such a modest decline across years suggests that this change is not biologically significant, potentially due to greater within-year variation in the condition factor than among years. In fact, when fitting a linear mixed model to the entire data set (N= 1136) and treating the year as a random effect, we observe higher within-year variability (σresidual= 0.116, 95% CI: [0.111, 0.121]) than the variability among years (σyear= 0.032, 95% CI: [0.018, 0.057]). Therefore, even if statistical significance had been observed (which we contend it was not), such a weak effect of year is likely an example of a statistically significant result where the effect size is not biologically significant5, 6. There are valid reasons to be concerned about the fate of Arctic Char in a rapidly changing Arctic7–9. The few longterm datasets available from the Canadian Arctic, however, do not suggest declines in abundance or body condition linked to climate change (e.g., refs. 10, 11). In fact, some studies even suggest a positive effect of an increased summer ice-free period on the condition of anadromous stocks12 (note however that the individuals studied in Lake Hazen are not anadromous). We conclude that the available evidence does not currently support the conclusion of a decline in condition DOI: 10.1038/s41467-018-06479-5 OPEN

Influence of Landing Net Mesh Type on Handling Time and Tissue Damage of Angled Brook Trout

Recreational catch-and-release angling is a popular activity. Anglers often use landing nets to shorten fight times, reduce stress on the line and rod, restrict fish movement to facilitate dehooking of the fish, and protect fish from undue harm caused by handling or dropping. Landing nets are constructed using a variety of netting materials that could have varied consequences when coming in contact with fish. Salmonids are among the most targeted fishes in the world, but little is known about how landing nets contribute to postcapture tissue damage. We compared handling time and instances of fin fraying, scale loss, and mucus loss sustained by Brook Trout Salvelinus fontinalis landed by four net mesh types (i.e., large, knotless rubber mesh; knotless nylon micromesh; large, knotted polypropylene mesh; and small, knotless rubber-coated nylon mesh) or by using bare wet hands in a recreational fishery. The knotted polypropylene mesh resulted in the greatest extent of fin fraying, whereas the bare wet hands method, knotless nylon micromesh, and rubber-coated nylon mesh resulted in the most scale loss. Interestingly, extended handling times were noted for several mesh types (i.e., knotless nylon micromesh and rubber-coated nylon mesh) relative to bare wet hands because of hook entanglement in the netting material. However, using bare wet hands to land Brook Trout resulted in higher odds of the fish being dropped into the bottom of the boat. We concluded that the large, knotless rubber mesh was the least damaging to Brook Trout. Changes to angler practices, such as using appropriate landing tools, can benefit fish welfare in catch-and-release fisheries. Recreational catch-and-release angling is a popular activity around the globe (Arlinghaus et al. 2007). The premise of catch and release, whether as a voluntary conservation action or as a mandatory action to comply with management regulations, is that the released fish survive with negligible tissue damage, stress, or other *Corresponding author: robertlennox9@gmail.com Received December 5, 2016; accepted October 17, 2017 North American Journal of Fisheries Management 38:76–83, 2018