Patterns of Wolf Dispersal Respond to Harvest Density across an Island Complex.

Wolves are highly mobile predators and can disperse across a variety of habitats and over long distances. However, less is known about dispersal capabilities across water and among islands. The biogeography of island systems fosters spatially structured local populations, and their degree of connectivity may influence the dynamics and long-term viability of the regional population. We sought to quantify wolf dispersal rate, distance, and dispersal sex bias throughout Prince of Wales Island, a 6670 km2 island in southeast Alaska, and the surrounding islands that constitute the wildlife management unit (9025 km2). We also investigated patterns of dispersal in relation to hunting and trapping intensity and wolf population density. We used DNA data collected during 2012-2021 long-term monitoring efforts and genotyped 811 wolves, 144 of which (18%) were dispersers. Annual dispersal rates were 9-23% and had a weakly positive relationship with wolf density. Wolves dispersed 41.9 km on average (SD = 23.7 km), and males and females did not disperse at different rates. Of the dispersing wolves, 107 died, and the majority (n = 81) died before they were able to settle. The leading manner of death was trapping (97% of mortalities), and wolves tended to disperse from areas with low harvest density to areas where harvest density was relatively higher. Dispersal occurred both to and from small islands and the larger Prince of Wales Island, indicating bidirectional as opposed to asymmetrical movement, and the genetic overlap of wolf groups demonstrates connectivity throughout this naturally patchy system. Island ecosystems have different predator-prey dynamics and recolonization processes than large, intact systems due to their isolation and restricted sizes; thus, a better understanding of the degree of population connectivity including dispersal patterns among islands in the Prince of Wales archipelago could help inform the management and research strategies of these wolves.

Benefits and risks of diversification for individual fishers.

Individuals relying on natural resource extraction for their livelihood face high income variability driven by a mix of environmental, biological, management, and economic factors. Key to managing these industries is identifying how regulatory actions and individual behavior affect income variability, financial risk, and, by extension, the economic stability and the sustainable use of natural resources. In commercial fisheries, communities and vessels fishing a greater diversity of species have less revenue variability than those fishing fewer species. However, it is unclear whether these benefits extend to the actions of individual fishers and how year-to-year changes in diversification affect revenue and revenue variability. Here, we evaluate two axes by which fishers in Alaska can diversify fishing activities. We show that, despite increasing specialization over the last 30 years, fishing a set of permits with higher species diversity reduces individual revenue variability, and fishing an additional permit is associated with higher revenue and lower variability. However, increasing species diversity within the constraints of existing permits has a fishery-dependent effect on revenue and is usually (87% probability) associated with increased revenue uncertainty the following year. Our results demonstrate that the most effective option for individuals to decrease revenue variability is to participate in additional or more diverse fisheries. However, this option is expensive, often limited by regulations such as catch share programs, and consequently unavailable to many individuals. With increasing climatic variability, it will be particularly important that individuals relying on natural resources for their livelihood have effective strategies to reduce financial risk.

Morphological Distribution of the Anterior Inferior Iliac Spine in Patients With and Without Hip Impingement: Reliability, Validity, and Relationship to the Intraoperative Assessment.

BACKGROUND: Subspinous impingement of the anterior inferior iliac spine (AIIS) on the femoral head-neck junction is increasingly recognized as a source of hip impingement. A classification system of AIIS morphology has previously been proposed that correlates with reduced hip motion and may predispose patients to subspinous hip impingement. PURPOSE: To examine the morphological distribution of AIIS types in patients with and without diagnosed hip impingement and correlate AIIS morphology to intraoperative findings at the time of surgery. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Three-dimensional reconstructed pelvic computed tomography scans were generated for a stratified sample of 449 hips in patients without a history of hip pain or hip impingement and 59 hips in patients with a diagnosis of hip impingement. Three blinded assessors classified the AIIS for each hip twice. The morphological distribution between symptomatic and asymptomatic patients was compared, controlling for age, sex, and affected side. Within the symptomatic cohort, AIIS morphology was compared with the intraoperative assessment of a low-lying AIIS using the Fisher exact test. RESULTS: The intraobserver reliability of the classification system in our cohort was substantial (κ = 0.68-0.77). The interobserver reliability was moderate (κ = 0.50). The morphological distribution between symptomatic and asymptomatic patients was similar, with 75% of patients in the asymptomatic group and 80% of the patients in the symptomatic group having a type 2 or type 3 AIIS. When matched for age, sex, and affected side, there was no significant difference in the assessed classification type between the groups ( P = .55). Within the symptomatic group, there was no significant correlation between the surgeon assessment of a low-lying AIIS and a type 2 or type 3 radiographic classification ( P = .10). The positive predictive value of a type 2 or type 3 AIIS classification for hip impingement symptoms was 10%, and the negative predictive value was 91%. CONCLUSION: These findings suggest that a high percentage of patients with AIIS morphology associated with subspinous impingement are, in fact, asymptomatic. The current radiographic classification scheme should not be used exclusively for clinical decision making.

Interannual and Spatial Variability in Maturity of Walleye Pollock Gadus chalcogrammus and Implications for Spawning Stock Biomass Estimates in the Gulf of Alaska.

Catch quotas for walleye pollock Gadus chalcogrammus, the dominant species in the groundfish fishery off Alaska, are set by applying harvest control rules to annual estimates of spawning stock biomass (SSB) from age-structured stock assessments. Adult walleye pollock abundance and maturity status have been monitored in early spring in Shelikof Strait in the Gulf of Alaska for almost three decades. The sampling strategy for maturity status is largely characterized as targeted, albeit opportunistic, sampling of trawl tows made during hydroacoustic surveys. Trawl sampling during pre-spawning biomass surveys, which do not adequately account for spatial patterns in the distribution of immature and mature fish, can bias estimated maturity ogives from which SSB is calculated. Utilizing these maturity data, we developed mixed-effects generalized additive models to examine spatial and temporal patterns in walleye pollock maturity and the influence of these patterns on estimates of SSB. Current stock assessment practice is to estimate SSB as the product of annual estimates of numbers at age, weight at age, and mean maturity at age for 1983-present. In practice, we found this strategy to be conservative for a time period from 2003-2013 as, on average, it underestimates SSB by a 4.7 to 11.9% difference when compared to our estimates of SSB that account for spatial structure or both temporal and spatial structure. Inclusion of spatially explicit information for walleye pollock maturity has implications for understanding stock reproductive biology and thus the setting of sustainable harvest rates used to manage this valuable fishery.