Jeffrey A. Stein

Hormonal responsiveness to stress is negatively associated with vulnerability to angling capture in fish

ABSTRACT Differences in behavior and physiology amongst individuals often alter relative fitness levels in the environment. However, the ideal behavioral/physiological phenotype in a given environment may be altered by human activity, leading to an evolutionary response in the affected population. One example of this process can be found in fisheries (including recreational freshwater fisheries), where selective capture and harvest of individuals with certain phenotypes can drive evolutionary change. While some life history traits and behavioral tendencies influencing capture likelihood have been studied, the physiological mechanisms driving this vulnerability remain poorly understood. To address this, we assessed how two major physiological characteristics (hormonal responsiveness to stress and metabolic phenotype) and one behavioral characteristic (boldness) impact the likelihood of an individual being captured by anglers. Largemouth bass, Micropterus salmoides, derived from a population artificially selected for differential angling vulnerability were assessed for boldness and for stress responsiveness (as indicated by plasma cortisol levels) following an air-exposure challenge. Largemouth bass were then stocked into a pond where experimental angling trials took place, and a subset of captured and uncaptured fish were afterwards assessed for metabolic phenotype. The results showed that stress responsiveness was the primary driver of angling vulnerability, with individuals that experienced lower rises in cortisol following the air-exposure challenge more likely to be captured. Neither boldness nor metabolic phenotype influenced capture probability. The results from this study indicate that fisheries-induced selective pressure may act on physiology, potentially altering stress responsiveness and its associated behaviors in populations exploited by recreational anglers. Highlighted Article: Fish showing lower hormonal stress responsiveness are more likely to be captured, indicating that stress physiology may be a trait under selection as a result of selective capture.

Chill out: physiological responses to winter ice-angling in two temperate freshwater fishes

We quantified physiological disturbance and reflex impairment in ice-angled bluegill and yellow perch. Rises in plasma cortisol and lactate following capture were lower than those found in prior studies done in summer. Recovery of plasma metrics did not occur within 4 h of capture, however, reflex responsiveness levels did recover.

Progress Toward Lake Trout Rehabilitation at a Stocked and Unstocked Reef in Southern Lake Michigan

AbstractSustained efforts to restore naturally reproducing populations through the stocking of marked juvenile Lake Trout Salvelinus namaycush have occurred since the 1960s but have been largely unsuccessful in achieving that goal. Julian’s Reef in southwestern Lake Michigan has been a targeted Lake Trout rehabilitation site since 1985 and was designated a first-priority site in a revised management strategy for Lake Trout rehabilitation in 2011. We evaluated progress toward rehabilitation objectives for spawning Lake Trout at Julian’s Reef and compared that progress to unstocked Waukegan Reef nearby in light of a recent increase to approximately 50% unmarked adults at both sites, as detected by annual fall spawning assessments. We observed significant progress toward meeting the rehabilitation objectives for adult Lake Trout in southern Lake Michigan. The spawning populations at Julian’s Reef and Waukegan Reef did not differ in relative abundance, sex ratio, age structure, or spawner sources (stocking lo...

Potential consequences of angling on nest-site fidelity in largemouth bass

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 salmoides, catch-and-release angling impacts individual nesting success and fitness through physiological disturbance and by removing the nest-guarding male from its brood, thereby allowing temporary access to eggs and hatchlings by brood predators. To assess the impact of catch-and-release angling on nest site fidelity, we compared the consequences of angling on individually marked (i.e., with passive integrated transponders) nest-guarding male Largemouth Bass in Ontario. An extremely high degree of nest site fidelity in year two was observed for males that were angled only once during year one (87% within 10 m of the previous year’s nest), 96.7% of which remained on the nest and completed parental care activities. There was significantly lower fidelity in year two, however, for males that were angled multiple times during year one (27% within 10m of the previous year’s nest), only 5.6% of which remained on the nest and completed parental care activities. This observed difference suggests that angling nesting bass may cause them to avoid previously used nest sites and instead search for alternative sites during future reproductive seasons. This human-induced impact on nest site choice may impact the future reproductive success of those Largemouth Bass.

Comment: Not all Biases are Created Equal—A Comment on the Snorkel Survey Bias Observed by Hessenauer et al. (2014)

Comment: Not all Biases are Created Equal—A Comment on the Snorkel Survey Bias Observed by Hessenauer et al. (2014) Jeffrey A. Stein, Julie E. Claussen, David P. Philipp & Steven J. Cooke a Illinois Natural History Survey, University of Illinois, 1816 South Oak Street, Champaign, Illinois 61820, USA b Fish Ecology and Conservation Physiology Laboratory, Institute of Environmental Science and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada Published online: 24 Nov 2014.

Sociable bluegill, Lepomis macrochirus, are selectively captured via recreational angling

Individuals often show considerable variance in social behaviour and aggression, leading to defined social roles. Removal of individuals with particular roles from groups may have impacts on group function, leaving those groups less able to locate critical resources and avoid danger. In recreational fisheries, capture by humans constitutes a mortality risk, and therefore angling has the potential to fundamentally alter social structure in exploited populations if individuals with defined social roles are disproportionately captured. However, little work has examined the linkage between social behaviour and angling vulnerability. To address this gap, we conducted a study on bluegill, Lepomis macrochirus, a freshwater fish known to be socially gregarious, and a common target of recreational anglers in North America. Fish were angled in a naturalistic pond setting, and a subset of captured and uncaptured fish was then assessed for sociability in a shoaling assay and aggression/dominance in paired dyadic contests. Results showed a significant effect of time spent in the social zone on capture status, with captured individuals spending significantly more time near a transparent divider separating it from a shoal of conspecifics compared to uncaptured fish. Dominance was not associated with angling vulnerability, and sociability was not linked with dominance. Collectively, these results show that more social bluegill are more likely to be captured by anglers. This could in turn lead to decreased social functionality in exploited populations as a result of the removal of particularly social individuals, as well as possible evolution of social behaviour in exploited populations due to this selection.

Relative bias and precision of age estimates among calcified structures of Spotted Gar Lepisosteus oculatus, Shortnose Gar Lepisosteus platostomus, and Longnose Gar Lepisosteus osseus

AbstractRecreational angling for gars Lepisosteidae has become more popular in recent years; however, the fundamental understanding of population dynamics needed for effective management and conservation is lacking. Age data are essential for describing population dynamic rate functions, but few studies have addressed selection of ideal calcified structures for use in estimating ages in gars. We collected Spotted Gars Lepisosteus oculatus, Shortnose Gars L. platostomus, and Longnose Gars L. osseus from twelve Illinois waterbodies to assess the relative bias and precision of age estimates among branchiostegal rays, pectoral fin rays, cleithra, and sagittal otoliths. Age assignments differed among calcified structures for all three species. Branchiostegal rays underestimated the age of young fish and overestimated the age of old fish relative to all other structures. Pectoral fin rays consistently underestimated age relative to other structures and produced the lowest mean and maximum age estimates. Low rel...