Harvesting Pressure Research Articles

Buffalo on the Edge: Factors Affecting Historical Distribution and Restoration of Bison bison in the Western Cordillera, North America

The historic western edge of the bison (Bison bison) range and the ecological processes that caused its formation are frequently debated with important implications for bison restoration across North America. We test the hypothesis that a combination of bottom-up habitat suitability and top-down harvest pressure from Indigenous peoples were important processes in forming the western edge of bison distribution. Using 9384 historical journal observations from 1691–1928, we employ MaxEnt ecological niche modelling to identify suitable bison habitat across the Western Cordillera from bottom-up climatic, land cover, and topographic factors. We then use mixed-effect logistic regression to test if bison occurrence in journal records can be in part explained by the abundance of humans, wolves, or grizzly bears, in addition to MaxEnt-derived habitat suitability. We find support for our hypothesis because of the limited suitable habitat in the Rocky Mountains that likely prevented westward bison dispersal from their core habitat, and there was a negative relationship between bison occurrence and human harvest pressure. On this basis, we propose that intensive human harvest from large populations in the Western Cordillera, subsidized by other wildlife, salmon, and vegetation resources, is an underappreciated socioecological process that needs to be restored alongside bison populations. Co-managing bison with Indigenous peoples will also mitigate the adverse effects of overabundant bison populations and maximize the ecological and cultural benefits of bison restoration.

Social Fish‐Tancing in Wisconsin: The Effects of the COVID‐19 Pandemic on Statewide License Sales and Fishing Effort in Northern Inland Lakes

AbstractThe first year of the COVID‐19 pandemic in 2020 was associated with an “anthropause” in many industries, initially reducing greenhouse gas emissions and other negative anthropogenic influences. However, outdoor recreation has exploded in popularity in response to closures of indoor recreation options, increased free time, and/or increased levels of stress. We tested for the effects of the COVID‐19 pandemic on the sale of fishing licenses in Wisconsin and on vehicle counts that were observed at public lake access points in Vilas County, Wisconsin, in 2020. In the summer of 2020, fishing license sales in Wisconsin, USA, increased, particularly among first‐time license purchasers for whom cumulative sales in 2020 increased by 71% and 35% compared with the previous 5‐year average for Wisconsin residents and nonresidents, respectively. Changes in the vehicle counts at lake access points in the summer of 2020 varied considerably by lake. However, lakes with greater proportions of public shoreline experienced pandemic‐associated increases in lake visitors. Our results suggest that the distribution of recreational fishing effort in Wisconsin changed during the pandemic, potentially placing additional harvest pressures on hot spot inland lakes.

Disproportionate admixture improves reintroduction outcomes despite the use of low‐diversity source populations: population viability analysis for a translocation of the greater stick‐nest rat

AbstractTranslocation is becoming an increasingly important approach to threatened species conservation. Coupled with the knowledge that maximizing genetic diversity aids population establishment, the growing use of translocations can place unsustainable harvesting pressure on critical and vulnerable source populations. However, adaptive, genetically informed modelling tools such as Population Viability Analysis (PVA) can be used to predict translocation outcomes and optimize harvesting strategies. In this study, we use PVAs for the frequently translocated greater stick‐nest rat (Leporillus conditor) to demonstrate the value of admixing founder populations for translocation, even when one source population is deemed genetically depauperate. This approach not only maximizes genetic diversity in the translocated population but reduces harvesting pressure on critical populations. Further, we show that admixed harvesting ratios can be skewed significantly towards the genetically depauperate population in order to further protect the critical population while still producing favourable outcomes, providing adequate founder numbers are used. As many threatened species are limited to fragmented and bottlenecked populations, these results are broadly applicable to the science of reintroduction biology, and demonstrate the value of PVAs for preliminary translocation planning and species management.

Dynamic Interdependence between Anglers and Fishes in Spatially Coupled Inland Fisheries

The cumulative harvest pressure exerted by recreational anglers can be intense in some locations. Sustainable management and conservation of inland fisheries requires an understanding of the spatial ecology of fish-angler interactions (e.g., direct, indirect, and feedback). Advancement towards this goal requires study of the complex interdependencies of human and natural systems, which can be achieved, in part, by looking beyond the wetted confines of individual waterbodies towards the broader angling landscape. It has been hypothesized that fish stocks should experience strong reductions in areas near large aggregations of recreational anglers where fishing effort is presumed to be greatest. To test this hypothesis, we examined a complex of direct, indirect, and feedback effects among recreational anglers, bluegill sunfish Lepomis macrochirus, and largemouth bass Micropterous salmoides across inland recreational fisheries (n = 29 reservoirs) using path analysis and structural equation modeling. We found that recreational anglers imparted detectable effects on recreational bluegill (direct) and bass (indirect) fisheries across the landscape, which we attributed to (1) short travel distances of individuals at local scales (<40 km), and (2) a spatially and numerically heterogeneous distribution of anglers (i.e., anglers within counties) at the regional scale. Our study identified the presence of an emergent landscape-scale feedback, driven by angler numbers, mediated via angling effects on bluegill and bass populations, and which manifested as spatially variable movements of anglers. These dynamics collectively shaped inland fisheries across the landscape via a suite of direct, indirect, and feedback effects and highlight the complex relationships between fishes and anglers. Consideration of direct and indirect effects of angling pressure from the landscape should aid in prioritizing or identifying areas in need of management, conservation, public outreach, and education, and improve understanding of how changes to one or many species may feedback to other social, ecological, and economic systems.

Effects of hunting pressure and timing of harvest on bighorn sheep (Ovis canadensis) horn size

Trophy hunting can affect weapon size of wild animals through both demographic and evolutionary changes. In bighorn sheep ( Ovis canadensis Shaw, 1804), intense harvest of young males with fast-growing horns may have partly driven long-term decreases in horn size. These selective effects could be dampened if migrants from protected areas, not subject to artificial selection, survived and reproduced within hunted populations. Bighorn rams undertake long-distance breeding migrations in the weeks preceding the late-November rut. We analysed records of >7800 trophy bighorn rams shot from 1974 to 2019 in Alberta, Canada, to test the hypothesis that high harvest pressure during breeding migrations was correlated with a greater decrease in horn size. We compared areas with and without a pronounced harvest peak in late October, when male breeding migrations begin. Areas without a pronounced harvest peak in late October, which likely experienced a lower harvest rate, showed a similar temporal decline in horn size, but no increase in age at harvest suggesting a possibly weaker decline in horn growth. Our study suggests that unselected immigrants from protected areas could partly buffer the effects of intense trophy hunting only if harvest pressure was reduced when breeding migrations commence.

Assessing the Stock Dynamics of Elasmobranchii off the Southern Coast of Sicily by Using Trawl Survey Data

Elasmobranchii (sharks and rays), which have peculiar and vulnerable life-history traits, are highly threatened by fishing activities. Indeed, between 53% and 71% of Mediterranean elasmobranch species are at risk of extinction. In this context, using the abundance MSY (AMSY) model, the present study provides an assessment of 20 batoids and 16 shark species in the Strait of Sicily, sampled during a bottom trawl survey from 1995 to 2020. Overall, the outputs underline a progressively improving condition for shark and ray assemblages of both shelf and eurybathic zones. As for slope-dwelling species, a horseshoe-shaped dynamic, characterized by a progressive decrease in relative harvesting pressure and an increase in relative biomass followed by an increase in fishing pressure and decrease in biomass, was detected. The dynamics of the Elasmobranchii living in the Strait of Sicily appear to be affected by changes in the fishing patterns of trawlers, showing a shift from shallow water to bathyal fishing grounds and targeting deep-water red shrimp. In this context, it seems wise to limit the impact of deep-water fisheries on Elasmobranchii by reducing fishing efforts and implementing ad hoc management measures aimed at safeguarding these vulnerable species.

Triboelectrification-Induced Electricity in Self-Healing Hydrogel for Mechanical Energy Harvesting and Ultra-sensitive Pressure Monitoring.

Triboelectric nanogenerators (TENGs) have shown huge application potential in the fields of micro–nano energy harvesting and multifunctional sensing. However, the damage of triboelectric material is one of the challenges for their practical applications. Herein, we fabricated a flexible TENG employing self-healing hydrogel and fluorinated ethylene propylene film as triboelectric materials for mechanical energy harvesting and pressure monitoring. The prepared hydrogel not only has excellent flexibility, transparency, and self-healing property but also exhibits good mechanical property without plastic deformation and damage under a large stretchable strain of 200%. The output electric signals of TENGs are as high as 33.0 V and 3 μA under a contact frequency of 0.40 Hz and a pressure of 2.9 N, respectively, which can charge a capacitor of 0.22 μF to 24.3 V within 300 s. Note that the voltage retention rate of TENGs after self-healing is up to 88.0%. Moreover, hydrogel-based TENGs can act as a wearable pressure sensor for monitoring human motion, exhibiting a high sensitivity of 105.9 mV/N or 1.73 nA/N under a contact frequency of 0.40 Hz. This research provides a reference roadmap for designing TENGs and self-powered pressure sensors with flexibility, self-healing, and robustness.

Status and distribution of wild turkeys in the United States in 2019

AbstractAfter increases following restoration efforts, the wild turkey (Meleagris gallopavo) population appeared to decline during the early 2000s in many areas of the species' range. The 2014 status assessment indicated that estimated population size, harvest, and hunter numbers had declined since at least 2009. Several studies concurrently detailed regional declines in productivity of wild turkey populations. During 2019, we continued to monitor status of wild turkey populations in the United States by surveying state agency biologists charged with overseeing wild turkey management programs. We asked biologists to provide estimates of population abundance and distribution within their state. We also requested that each biologist provide data on turkey hunter numbers and harvest for both spring and fall hunting seasons, if those data were available. Based on agency biologist responses, wild turkey population size declined by ~3% across states that contributed data to both the 2014 and 2019 status updates. However, during our 2019 survey, abundance data were unavailable for 12 states that reported estimates for the 2014 assessment. We estimated that the number of wild turkey hunters declined by 18% between the 2014 and 2019 assessments, but note the 2019 estimate was confounded by missing data from 8 states that provided data during 2014. Across all reporting states, fall and spring harvests decreased by 31 and 12%, respectively, between the 2014 and 2019 assessments. Despite widespread recognition that standardization of monitoring methods across states would facilitate more consistent inferences about wild turkey abundance, further progress towards regional or national standardization is needed. Furthermore, the approach of converting harvest data to a population estimate by dividing harvest estimates by a constant percentage of estimated take should be revisited to ensure accuracy, especially given known spatial and temporal variation in harvest pressure, hunting activity, and hunter behavior. We encourage continued development of improved techniques to estimate wild turkey abundance and distribution, and recommend that all states and provinces consider standardized methods to accurately monitor and report harvest and hunter effort.

Balancing wood production and biodiversity in intensively managed boreal forest

ABSTRACT Fennoscandian boreal forests are managed intensively for wood production, which has had a negative impact on biodiversity. The harvesting pressure on the forests is likely to increase in the future because wood is seen as an important resource in a bio-based economy. Thus, there is an urgent need to better describe the trade-offs between wood production and biodiversity, and to understand how these trade-offs can be alleviated by adapting forest management. Encompassing a broad range of biodiversity aspects, we studied how forest management can increase biodiversity indicators while maintaining or increasing current harvest levels. We found that there is considerable leeway for forestry to pursue multiple objectives simultaneously in Fennoscandian forest landscapes. We show that it is possible to both increase harvests and structural elements of importance for biodiversity compared to present levels in a forest landscape that is representative of conditions in boreal forests in northern Sweden. Achieving this requires a variation in management strategies at the landscape level, and an adaptation of management practices to explicitly consider and implement multiple objectives in the planning process.

Large‐scale fabrication of core‐shell triboelectric braided fibers and power textiles for energy harvesting and plantar pressure monitoring

AbstractFlexible and wearable energy harvesting devices and multifunctional sensors have been widely reported, but challenges in the large‐scale manufacturing process still exist. This work reports a large‐scale fabrication method of core‐shell triboelectric braided fibers that exhibit stable structure and strong tensile strength, which can be further integrated into power textiles with different fabric structures, such as weaving and knitting, with the purpose of biomechanical energy harvesting or plantar pressure monitoring. The triboelectric braided fibers integrating on the knitting power textiles exhibit good pressure sensitivity and fatigue resistance, which is combined with traditional socks to measure the pressure distribution of the plantar in different positions. The weaving power textiles exhibit high electrical output, which can be used for biomechanical energy harvesting and can easily light up 116 commercial LEDs. This large‐scale preparation approach provides more possibilities for power textiles applications in self‐powered wearable electronics and human–computer interfacing.

Development of novel genome‑wide simple sequence repeats (SSR) markers in Bunium persicum

Bunium persicum (Boiss.) Fedtsch or Kala jeera is an economically important medicinal spice that grows in cold temperate regions of Central Asia and Northern India. It is mainly used as spice and condiment in various food preparations. However, its high aroma and richness in essential oils make it industrially important. The bioactivity and pharmacological activities of its phytochemicals have been well elucidated. Due to limited cultivation and huge harvest pressure on natural resources, this species is under severe threat of diversity loss. Further, genetics and molecular breeding studies are lagging for this important crop plant due to a dearth of efficient genome wide molecular markers. In the present study, genomic resources for B. persicum have been generated for the first time through de novo sequencing. In addition, novel genomic SSRs from these resources are identified for their use in future diversity analysis and breeding programs. A total of 177029 perfect and 5915 compound SSR motifs were identified in 212585 assembled sequences. Mononucleotide repeats were the most abundant (55.18%) followed by di- (32.35%), tri- (7.21%), tetra- (3.15%) and hexa- nucleotide (0.76%) repeats. Total 101519 and 2649 primers were successfully designed for sequences containing perfect and compound SSR repeat motifs, respectively. For validation, 88 primer pairs were synthesized for perfect SSR motifs, from which 68 pairs gave scorable amplification. From these, 16 primer pairs were found monomorphic and 52 were polymorphic. These 68 primer pairs altogether yielded 101 alleles with an average of 1.71 alleles per loci. Overall average allele frequency (0.7908), PIC value (0.213), heterozygosity value (0.2995), and gene diversity (0.2680) was recorded for the evaluated Bunium accessions. UPGMA tree constructed based on Nei genetic distances successfully distinguished the evaluated B. persicum accessions. Low genetic diversity recorded in the present study emphasizes the need for restoration and maintenance of effective B. persicum population sizes in situ for its future sustenance.

Loss of surficial sedimentary carbon stocks in seagrass meadows subjected to intensive clam harvesting

Seagrass carbon stocks are vulnerable to physical disturbance. We assessed the effect of clam harvesting on the organic carbon (Corg) stocks in surface sediments in four intertidal Zostera noltei meadows on the Iberian Atlantic coast (Spain and Portugal), by comparing undisturbed and harvested areas. We also monitored the spatial cover of the meadows throughout the growing season. Sedimentary Corg content and Corg stocks were about four times lower in intensively harvested areas than in control areas, but there were not differences between areas with low harvesting pressure and control areas. Reductions of 53–85% in sedimentary Corg stocks of Z. noltei meadows were caused by intensive clam harvesting. The effect of intensive clam harvesting on Corg stocks increased throughout the growing season, but the area covered by the seagrass increased from 21 to 37%, suggesting rapid recovery of seagrass canopies and potential recovery of sedimentary Corg stocks.

Pathogen‐mediated selection and management implications for white‐tailed deer exposed to chronic wasting disease

Abstract Pathogens can cause host extinction, affect population dynamics and influence natural selection. Host susceptibility to pathogens can vary by species, demographics and genetics which affect epizootic and population dynamics, ultimately determining population trends and evolution. Chronic wasting disease (CWD), a fatal neuro‐degenerative prion disease of cervids, has varying host susceptibility conferred by polymorphisms of the prion protein gene (PRNP) at codon 96 for white‐tailed deer Odocoileus virginianus. Deer with the homozygous Glycine allele (96GG) are most susceptible and a single Serine allele (96GS/96SS) reduces the risk of infection and mortality. We developed epizootiological models that demonstrate CWD infection and disease‐associated mortality were higher for the more susceptible (96GG) genotype; and, infection was higher for males than females. We used population models to evaluate future shifts in genotype frequencies under alternative harvest and infection rate scenarios. Genetic shifts towards less susceptible genotypes were predicted as CWD prevalence increased during the course of an outbreak. This further increased CWD prevalence, and likely environmental contamination from prion shedding, due to longer incubation periods. Alternative harvest management strategies directly influenced CWD prevalence and spread, the rate of genetic selection and deer population growth. Synthesis and applications. We show that chronic wasting disease (CWD) transmission varied by sex, age class and PRNP genotype, and that CWD disease‐associated mortality varied by genotype. Together, these forces lead to CWD‐mediated genetic selection for a white‐tailed deer population. We predict that genetic selection pressure increases when hunter harvest pressure is lowered, and conversely, increasing hunter harvest can reduce genetic selection rates of antlered deer. Our results support the control of CWD prevalence by aggressive harvest of adult males, because they have the highest infection rates. Our results have strong implications for evolution, disease ecology, geographical spread, disease mitigation and cervid population management.

Alternative restocking strategy could reverse declines of a critically endangered sturgeon

SummaryDemographic modelling can reveal options for improved conservation management, especially for rare or long-lived species not amenable to experimentation. Sturgeon (Acipenseridae) include many such species, endangered by demand for caviar, their unfertilized roe, and by dams blocking their migrations. Restocking of sturgeon populations with farm-raised individuals has probably prevented extinctions and widespread extirpations of some species, but it has rarely led to true recovery in Eurasia, given ongoing harvest. We used modified Leslie matrix models to test whether restocking with year-old juveniles instead of weeks-old fry could recover the critically endangered Amur sturgeon (Acipenser schrenckii), endemic to the Amur River basin along the Russia–China border. Without restocking, or even releasing an expert-recommended annual volume of young fry (10 million), we project that three of four Amur sturgeon populations will be nearly extirpated within 30 years. However, restocking with 5% as many (500 000) year-old juveniles annually could grow three populations (currently 0–425 mature females) and slow declines in another so that each has over 6400 mature females within 30 years. Retooling stocking efforts to use fewer juveniles that survive at higher rates than do small fry could buy time to reduce harvesting pressure on Amur sturgeon and for other related sturgeon species.

Opposing trends in survival and recruitment slow the recovery of a historically overexploited fishery

Quantifying temporal variation in demographic rates is a central goal of population ecology. In this study, we analyzed a multidecadal age-structured time series of Arctic char (Salvelinus alpinus) abundance in Lake Mývatn, Iceland, to infer the time-varying demographic response of the population to reduced harvest in the wake of the fishery’s collapse. Our analysis shows that while survival probability of adults increased following the alleviation of harvesting pressure, per capita recruitment consistently declined over most of the study period, until the final three years when it began to increase. The countervailing demographic trends resulted in only limited directional change in the total population size and population growth rate. Rather, the population dynamics were dominated by large interannual variability and a shift towards an older age distribution. Our results are indicative of a slow recovery of the population after its collapse, despite the rising number of adults following relaxed harvest. This underscores the potential for heterogeneous demographic responses to management efforts due to the complex ecological context in which such efforts take place.

Spatial and Temporal Analyses of Bobwhite Hunting Dynamics

A variety of factors influence the harvest of northern bobwhites (Colinus virginianus) and where that harvest occurs on a landscape. Many of these factors can be quantified and manipulated to distribute harvest pressure across time and space to meet desired spring densities. We collected spatial hunting metrics using global positioning system units on trucks and hunting dogs, along with detailed hunting logs from 211 quail hunts during the 2018–2019, 2019–2020, and 2020–2021 statewide hunting seasons in Jim Hogg County, Texas, USA. We found that hunting parties effectively covered 23.8 ± 0.3 hectares per hour, with hunts lasting 3.5 ± 0.1 hours in the morning and 1.7 ± 0.1 hours in the evening. Hunts were less productive during the early season (November–mid-December), with 13% fewer encounters per hour and 31% lower harvest per encounter. We expected daily harvest to increase with hunt velocities, but found no significant relationship with the velocity of either pointing dogs or vehicles. However, as we predicted, total hunting pressure (hunts per 50-meter × 50-meter area) decreased by 12% (range = 7–17) for every 5% increase in brush density and every 10-meter increase in the distance to the nearest access road. Our findings can assist landowners and managers in the distribution of harvest and hunting pressure across properties and hunting seasons.

A demographic model to support customary management of a culturally important waterfowl species

Scientific support invited by Indigenous peoples and local communities (IPLC) to assist with customary environmental management can improve conservation and community livelihoods. For example, demographic models can help to understand how alternative wildlife management strategies affect population dynamics and harvest sustainability. We developed a demographic model to assist Ngāi Tahu, the southern-most Māori tribe in Aotearoa/New Zealand, in customary management of a culturally important population of Black Swans (<em>kakī anau</em>, <em>Cygnus atratus</em>). We used recent demographic data, including results of an experimental egg harvest study, to inform <em>tangata tiaki</em> (Ngāi Tahu environmental guardians) about how customary egg harvest and background pressure from sport hunting of swans aged ≥ 1 year differentially affect population growth. We also assessed how sport hunting of swans affects the sustainability of customary egg harvest. Estimated population growth (1.018 or presently growing 1.8% annually; 95% CI: 0.808–1.241) was most sensitive to changes in adult and subadult survival, followed by juvenile (first-year) survival, breeding propensity, and nest hatching success. Uncertainty in population growth was almost entirely attributable to uncertainty in swan survival rates after hatching. Sustainable population-level rates of egg harvest varied from none to more than half of all eggs, depending on small changes in adult and subadult survival. Population sensitivity to adult and subadult survival suggests that limiting and monitoring their mortality are crucial to population and egg harvest sustainability, whereas contemporary government-mandated species management, through Fish and Game New Zealand, allows adult and subadult mortality from sport hunting, with little record of offtake. Recognizing the rights and interests of Ngāi Tahu, and monitoring swan mortality more closely, could improve Ngāi Tahu abilities to practice customary harvest, enhance population and environmental monitoring, and, when appropriate, control swan numbers in a culturally appropriate and less wasteful way. The model we present could aid decision making and communication between Ngāi Tahu and New Zealand’s Crown government within a potential future co-management arrangement. Demographic models can be useful tools for supporting customary environmental management, but developing, maintaining, and implementing these tools requires support for adaptive policies and management arrangements that recognize IPLC rights to the environment and decision making.

Interaction Effect of Plant Growth Regulators on Shoot Micropropagation of Aromatic Plant &amp;lt;i&amp;gt;Origanum elongatum&amp;lt;/i&amp;gt; (Bonnet) Emberger &amp;amp; Maire

Origanum elongatum (Bonnet) Emb. & Maire, is a medicinal, aromatic and endemic plant of Morocco, characterized by its pharmacological effects, and is commonly used for the production of essential oils and aromas, resulting in high harvest and overexploitation pressure. This is why the present study aims to implement the in vitro micropropagation of Origanum elongatum for optimal vitroplant production. Six macroelements were tested (SH, SD, N30K, MS, MSm and B5) and the SD medium was selected for vegetative propagation of the explants. Seven cytokinins: adenine (Ad), N6-(2-Isopentenyl) adenine, zeatin (Zeat), kinetin (Kin), benzyladenine (BAP), 1,3-diphenylurea (DPU) and thidiazuron (TDZ) were then evaluated at five concentrations (0.44, 1.33, 2.22, 3.11 and 4.44 μM/L) on growth, development, budding, rooting and hyperhydricity. 0.44 μM Kin was selected and combined with three auxins: indole-3-acetic acid (IAA), indole-3-butyric acid (AIB), and 1-naphthaleneacetic acid (NAA) at four concentrations (1.14, 2.85, 4.56 and 6.27 μM/L) to improve rooting and association with 1.14 μM IAA was shown to be efficient for roots development. Different concentrations of gibberellic acid (0.29, 1.5, 2.60 and 2.89 μM/L), combined with 0.44 μM/L Kin and 1.14 μM/L IAA, were tested and 2.60 μM/L GA3 gave maximum buds and shoots. Then, the combination of three polyamines at five concentrations (1.134, 3.402, 5.67, 7.938 and 11.34 μM/L) with 0.44 μM Kin and 1.14 μM/L IAA showed an increase in the number of buds and shoots for 7.938 μM/L putrescine and 3.402 μM/L spermine. Finally, seedlings with good foliar and root development were acclimatized.

Migration chronology and movements of adult American black ducks Anas rubripes wintering in Nova Scotia, Canada

American black ducks, native to eastern North America, have been the focus of significant international conservation and management programs. The combined USA and Canadian population has traditionally been managed as a single population; however black duck demographics may vary by region. To help understand potential regional differences in black ducks, we used satellite telemetry to assess migratory chronology and movements of black ducks wintering near Windsor, Nova Scotia, Canada, near the northern limits of their wintering range where numbers are increasing. Wintering black ducks from Nova Scotia did not leave the Atlantic Flyway and included both longer‐distance migrants (~ 1500 km north) and locally‐breeding individuals. None of our tracked ducks travelled south of Nova Scotia during any part of the annual cycle, indicating a population segment that never leaves Canada and is subject solely to Canadian harvest pressures. Band recovery data revealed that a small portion (2.4%) of black ducks originally banded during winter in Nova Scotia were recovered south along the east coast of the USA, indicating that some of these black ducks are subject to international harvest pressures. Our results show that there are differences in annual black duck movements even within a small part of their range, adding to the growing evidence that black duck populations show fine‐scale temporal and spatial structure. This structure will need to be considered in future interprovincial and international harvest management plans of this important species.

Bottom–up trophic effects on fisher Pekania pennanti harvest age structure: associations with mast, voles and owls

Harvest management quotas for fishers Pekania pennanti in some jurisdictions are estimated from the previous year's harvest, and stem from the hypothesis that age ratios in the harvest are largely influenced by ‘top–down’ trapping pressure. The influence of ‘bottom–up’ food supply on fisher harvest age ratios might be underappreciated, which could result in a misallocation of quotas in management planning. We assessed a variety of data sources to test the influence of bottom–up processes on fisher populations in Ontario, Canada. We found evidence that bottom–up trophic effects influence the harvested fisher age structure in some regions of Ontario. Evidence also suggests that harvest pressure had little top–down influence on age ratios over the course of our study, and that basing management strategies on this assumption may lead to unintentional overharvest in years of low productivity. We suggest several trophic linkages with potential to facilitate fisher management, including connections among berry and seed crops, small mammals and northern saw-whet owls Aegolius acadicus.