4-year Time Lag Research Articles

Temporal Transferability of Calibrated Hydrological Model Parameters: A Case Study of Gin Catchment, Sri Lanka

Lack of observed data for model calibration hinders the application of hydrological models in many poorly-gauged catchments, particularly in the humid tropical region. Despite much less attention given, it is vital to assess transferability of calibrated parameters in order to apply hydrological models in such catchments to assist their water resources planning and management activities. Thus, this study investigated temporal transferability of a lumped conceptual hydrological model’s (MIKE 11 NAM) calibrated model parameters for rainfall-runoff simulations in two different time periods beyond its calibration period. Study area was selected as Gin catchment located in the humid tropical region. MIKE 11 NAM model was calibrated for the period 1995-1998 [Nash Sutcliffe coefficient (NSE) = 0.73, percent bias (PBIAS) = 3.9%, ratio of the root mean square error to the standard deviation of measured data (RSR) = 0.52] and validated for the period 1999-2002 (NSE=0.66, PBIAS = 8.7%, RSR = 0.59) for the Gin catchment. The temporal transferability of the calibrated model parameters was tested using two scenarios which formulated based on the temporal lag between the calibration period and the transfer period: scenario A having a 4-year time lag and scenario B having a 8-year time lag. Scenario A which evaluated the model performance using 2003-2006 streamflow data indicated only a marginal loss in the model performance in comparison to the calibration. It showed an overall ‘good’ performance (NSE=0.64, PBIAS = 8.6%, RSR = 0.59) including promising capability to reproduce the peak flows (<10th percentile) with Pearson’s correlation coefficient of 0.6. However, scenario B which evaluated the model performance using 2007-2010 streamflow data indicated ‘unsatisfactory’ model performance (NSE=0.42, PBIAS = 13.6%, RSR = 0.76). Therefore, this study suggests that the calibrated parameters of MIKE 11 NAM model can be temporally transferred within a catchment with a 4-year time lag from the calibration period implying the applicability of this modelling framework for rainfall-runoff simulations especially in the catchments where streamflow data is sparse.

Tropicalization of demersal megafauna in the western South Atlantic since 2013

Temperatures in the southwest South Atlantic Ocean have increased over recent decades due to changes in Brazil's Current dynamics affecting marine ecosystems. However, the effects of ocean warming on demersal fauna in the region are poorly understood. Here, we analyse megafauna species composition, and changes in biomass of species with warm- and cold-water affinities for 29,021 commercial demersal catches landed in the harbours of Santa Catarina state, Brazil, between 2000 and 2019. We find evidence of megafauna tropicalization in the Brazilian Meridional Margin during this period. The mean temperature of catches has increased sharply since 2013, with the averaged optimal temperature preferences of all species in commercial catches in one year increasing at a rate of 0.41 °C yr−1. These changes in the mean temperature of the catch correlate well with model-based bottom water temperatures (with 0 and 1-year time-lag) and transport volumes of the Brazil Current (with 3 and 4-year time-lag).

Exposure to negative acts at work and self-labelling as a victim of workplace bullying: The role of prior victimization from bullying

The present study examines employees’ prior victimization from bullying in school or at work as a predictor of 1) their current exposure to negative social acts at work and 2) the likelihood of labelling as a victim of workplace bullying, and 3) whether the link between exposure to negative acts at work and the perception of being bullied is stronger among those who have been bullied in the past. We tested our hypotheses using a probability sample of the Norwegian working population in a prospective design with a 5-year time lag (N = 1228). As hypothesized, prior victimization positively predicted subsequent exposure to negative acts, which in turn was related to a higher likelihood of developing a perception of being a victim of workplace bullying. However, contrary to our expectations, prior victimization from bullying did not affect the relationship between current exposure to negative acts at work and the likelihood of self-labelling as a victim. Taken together, the results suggest that employees’ prior victimization is a risk factor for future victimization, yet overall plays a rather modest role in understanding current exposure to negative acts and self-labelled victimization from bullying at work.

Short Leukocyte Telomeres, But Not Telomere Attrition Rates, Predict Memory Decline in the 20-Year Longitudinal Betula Study.

Leukocyte telomere length (LTL) is a proposed biomarker for aging-related disorders, including cognitive decline and dementia. Long-term longitudinal studies measuring intra-individual changes in both LTL and cognitive outcomes are scarce, precluding strong conclusions about a potential aging-related relationship between LTL shortening and cognitive decline. This study investigated associations between baseline levels and longitudinal changes in LTL and memory performance across an up to 20-year follow-up in 880 dementia-free participants from a population-based study (mean baseline age: 56.8 years, range: 40–80; 52% female). Shorter baseline LTL significantly predicted subsequent memory decline (r = .34, 95% confidence interval: 0.06, 0.82), controlling for age, sex, and other relevant covariates. No significant associations were however observed between intra-individual changes in LTL and memory, neither concurrently nor with a 5-year time-lag between LTL shortening and memory decline. These results support the notion of short LTL as a predictive factor for aging-related memory decline, but suggest that LTL dynamics in adulthood and older age may be less informative of cognitive outcomes in aging. Furthermore, the results highlight the importance of long-term longitudinal evaluation of outcomes in biomarker research.

Solar and volcanic forcing of North Atlantic climate inferred from a process-based reconstruction

Abstract. The effect of external forcings on atmospheric circulation is debated. Due to the short observational period, the analysis of the role of external forcings is hampered, making it difficult to assess the sensitivity of atmospheric circulation to external forcings, as well as persistence of the effects. In observations, the average response to tropical volcanic eruptions is a positive North Atlantic Oscillation (NAO) during the following winter. However, past major tropical eruptions exceeding the magnitude of eruptions during the instrumental era could have had more lasting effects. Decadal NAO variability has been suggested to follow the 11-year solar cycle, and linkages have been made between grand solar minima and negative NAO. However, the solar link to NAO found by modeling studies is not unequivocally supported by reconstructions, and is not consistently present in observations for the 20th century. Here we present a reconstruction of atmospheric winter circulation for the North Atlantic region covering the period 1241–1970 CE. Based on seasonally resolved Greenland ice core records and a 1200-year-long simulation with an isotope-enabled climate model, we reconstruct sea level pressure and temperature by matching the spatiotemporal variability in the modeled isotopic composition to that of the ice cores. This method allows us to capture the primary (NAO) and secondary mode (Eastern Atlantic Pattern) of atmospheric circulation in the North Atlantic region, while, contrary to previous reconstructions, preserving the amplitude of observed year-to-year atmospheric variability. Our results show five winters of positive NAO on average following major tropical volcanic eruptions, which is more persistent than previously suggested. In response to decadal minima of solar activity we find a high-pressure anomaly over northern Europe, while a reinforced opposite response in pressure emerges with a 5-year time lag. On centennial timescales we observe a similar response of circulation as for the 5-year time-lagged response, with a high-pressure anomaly across North America and south of Greenland. This response to solar forcing is correlated to the second mode of atmospheric circulation, the Eastern Atlantic Pattern. The response could be due to an increase in blocking frequency, possibly linked to a weakening of the subpolar gyre. The long-term anomalies of temperature during solar minima shows cooling across Greenland, Iceland and western Europe, resembling the cooling pattern during the Little Ice Age (1450–1850 CE). While our results show significant correlation between solar forcing and the secondary circulation pattern on decadal (r=0.29, p<0.01) and centennial timescales (r=0.6, p<0.01), we find no consistent relationship between solar forcing and NAO. We conclude that solar and volcanic forcing impacts different modes of our reconstructed atmospheric circulation, which can aid in separating the regional effects of forcings and understanding the underlying mechanisms.

Dementia risk with antihypertensive use and blood pressure variability: A cohort study.

To determine the association between discrete antihypertensive drug classes and incident dementia controlling for blood pressure variability (BPV) in the preceding 4 years. A total of 6,537 participants (mean age 79 years, 62% women) in a prospective population-based cohort were followed up for incident dementia. A 4-year time lag period was created to classify drug exposure and measure blood pressure. BPV (percent coefficient of variation [CV]) was regressed against 9 antihypertensive drug classes (BPVreg). Cox regression models were employed to determine hazard ratios (HRs) for incident dementia thereafter according to drug class, adjusted for mean blood pressure, covariates, and BPV or BPVreg. Over a median 8.4 years follow-up (interquartile range 6.7-9.0), lower dementia risk was associated with nondihydropyridine calcium channel blocker (HR 0.56; 95% confidence interval [CI] 0.31-1.00, p = 0.05) and loop diuretics (HR 0.45; 95% CI 0.22-0.93, p = 0.03) after adjusting for CV-BPV. Similar findings were obtained in analyses restricted to antihypertensive drug users for nondihydropyridine calcium channel blocker (HR 0.52; 95% CI 0.28-0.95, p = 0.03) and loop diuretics (HR 0.40; 95% CI 0.19-0.83, p = 0.01). All systolic BPV × antihypertensive drug interaction terms were not different from p < 0.05. Nondihydropyridine calcium channel blocker and loop diuretics were associated with a reduced dementia risk independent of CV-BPV in the preceding 4 years. Systolic BPV was not the primary mechanism through which antihypertensive drug classes lower dementia risk.

Characterizing rainfall of hot arid region by using time-series modeling and sustainability approaches: a case study from Gujarat, India

This study aimed at characterization of rainfall dynamics in a hot arid region of Gujarat, India by employing time-series modeling techniques and sustainability approach. Five characteristics, i.e., normality, stationarity, homogeneity, presence/absence of trend, and persistence of 34-year (1980–2013) period annual rainfall time series of ten stations were identified/detected by applying multiple parametric and non-parametric statistical tests. Furthermore, the study involves novelty of proposing sustainability concept for evaluating rainfall time series and demonstrated the concept, for the first time, by identifying the most sustainable rainfall series following reliability (R y), resilience (R e), and vulnerability (V y) approach. Box–whisker plots, normal probability plots, and histograms indicated that the annual rainfall of Mandvi and Dayapar stations is relatively more positively skewed and non-normal compared with that of other stations, which is due to the presence of severe outlier and extreme. Results of Shapiro–Wilk test and Lilliefors test revealed that annual rainfall series of all stations significantly deviated from normal distribution. Two parametric t tests and the non-parametric Mann–Whitney test indicated significant non-stationarity in annual rainfall of Rapar station, where the rainfall was also found to be non-homogeneous based on the results of four parametric homogeneity tests. Four trend tests indicated significantly increasing rainfall trends at Rapar and Gandhidham stations. The autocorrelation analysis suggested the presence of persistence of statistically significant nature in rainfall series of Bhachau (3-year time lag), Mundra (1- and 9-year time lag), Nakhatrana (9-year time lag), and Rapar (3- and 4-year time lag). Results of sustainability approach indicated that annual rainfall of Mundra and Naliya stations (R y = 0.50 and 0.44; R e = 0.47 and 0.47; V y = 0.49 and 0.46, respectively) are the most sustainable and dependable compared with that of other stations. The highest values of sustainability index at Mundra (0.120) and Naliya (0.112) stations confirmed the earlier findings of R y–R e–V y approach. In general, annual rainfall of the study area is less reliable, less resilient, and moderately vulnerable, which emphasizes the need of developing suitable strategies for managing water resources of the area on sustainable basis. Finally, it is recommended that multiple statistical tests (at least two) should be used in time-series modeling for making reliable decisions. Moreover, methodology and findings of the sustainability concept in rainfall time series can easily be adopted in other arid regions of the world.

Is Foreign Aid Working? The Impact of Foreign Aid on Savings, Investment, and Economic Growth in Haiti

Despite increases in foreign aid inflow to Haiti, the country remains one of the poorest in the world. Findings regarding the benefits of foreign aid have been inconsistent. The purpose of this quantitative, archival study was to examine the extent to which total foreign aid explained gross domestic savings, gross domestic investment, and GDP growth rates in Haiti from 1975 to 2010 after 3-year, 4-year, and 5-year time lags. Foreign aid was disaggregated into grants and concessional loans. Data were drawn from the World Bank, the International Monetary Fund, and the Organization for Economic Cooperation and Development from 1970 to 2010. To analyze the extent to which total foreign aid predicted gross domestic savings and gross domestic investment, weighted least squares regression analyses were conducted, with per capita income, interest rates, and inflation rates as covariates. To examine the degree to which total foreign aid predicted GDP growth rates, multiple linear regression analyses were conducted, with consumption, government spending, gross domestic investment, and net trade balance as covariates. Foreign aid did not predict gross domestic savings for 3-year time lag, F (5, 30) = 1.32, p =.28; 4-year time lag, F (5, 30) = 1.24, p =.32, or 5-year time lag, F(5,30) = 1.30, p =.15. Foreign aid did not predict gross domestic investment for 3-year time lag, F(5, 30) = 1.49, p =.22; 4-year time lag, F(5,30)= 1.73, p =.16, or 5-year time lag, F(5, 30) = 2.29, p =.07. Foreign aid did not predict GDP growth rates for 3-year time lag, F(6, 29), p =.44; 4-year time lag, F(6, 29) = 1.11, p =.38, or 5-year time lag F(6, 29) = 0.83, p =.56. Findings showed that foreign aid inflows to Haiti have not predicted improved economic development. Future research should focus on determining the relationship between foreign aid and government investment in infrastructure, education, health, and social projects. The discussion should shift from whether foreign aid flows to developing countries are effective to how to make the allocation of foreign aid inflows more effective. The result would be improved use of the inflow of foreign aid and improved economic and social progress in developing nations.

Caries experience in the primary dentition and presence of plaque in 7-year-old Chinese children: A 4-year time-lag study.

Objectives:The aim of the present study was to test the hypothesis that dental caries prevalence and caries experience in primary dentitions has increased over 4 years and to compare the presence of plaque on permanent teeth in child cohorts over 4 years.Materials and Methods:A time-lag study design was used comprising two cohorts of children aged 7 years from the same five primary schools in Wuhan examined in 2007 and 2011. Two calibrated examiners visually assessed plaque accumulation according to the Greene and Vermillion Index and the dentitions according to the Atraumatic Restorative Treatment (ART) caries criteria. Analysis of variance (ANOVA), logistic regression, and Chi-square test were used to test for differences between dependent and independent variables.Results:The 2007 sample consisted of 817 children and the 2011 sample consisted of 1010 children. The prevalence of dental caries (d3mft) was 68.2% in 2007 and 67.7% in 2011, while that of d2mft was 78.5% in 2007 and 71.4% in 2011 (P < 0.0006). The mean d3mft score was 2.8 in 2007 and 3.1 in 2011 (P = 0.046), while the mean d3mfs score was 4.9 in 2007 and 7.3 in 2011 (P < 0.0001). The d3-component of the d3mft index was 73% in 2007 and 69% in 2011, while the f-component was 22% in 2007 and 26% in 2011. The hypothesis was not accepted. The proportion of children with plaque code 3 (extensive coverage) was higher in 2011 (21.8%) than in age mates in 2007 (5.7%).Conclusions:There were no obvious signs that dental caries prevalence had been increased in primary dentitions of this child population between 2007 and 2011. But as the mean caries experience scores at the surface level were higher in 2011 than in 2007, monitoring caries prevalence remains essential, but should start at an earlier age than that covered by this study. Health and educational authorities should collaborate in setting up programs aimed at ensuring good oral health for school children.

Unemployment, public-sector healthcare spending and stomach cancer mortality in the European Union, 1981-2009.

We sought to determine the association between changes in unemployment, healthcare spending and stomach cancer mortality. Multivariate regression analysis was used to assess how changes in unemployment and public-sector expenditure on healthcare (PSEH) varied with stomach cancer mortality in 25 member states of the European Union from 1981 to 2009. Country-specific differences in healthcare infrastructure and demographics were controlled for 1- to 5-year time-lag analyses and robustness checks were carried out. A 1% increase in unemployment was associated with a significant increase in stomach cancer mortality in both men and women [men: coefficient (R)=0.1080, 95% confidence interval (CI)=0.0470-0.1690, P=0.0006; women: R=0.0488, 95% CI=0.0168-0.0809, P=0.0029]. A 1% increase in PSEH was associated with a significant decrease in stomach cancer mortality (men: R=-0.0009, 95% CI=-0.0013 to -0.005, P<0.0001; women: R=-0.0004, 95% CI=-0.0007 to -0.0001, P=0.0054). The associations remained when economic factors, urbanization, nutrition and alcohol intake were controlled for, but not when healthcare resources were controlled for. Time-lag analysis showed that the largest changes in mortality occurred 3-4 years after any changes in either unemployment or PSEH. Increases in unemployment are associated with a significant increase in stomach cancer mortality. Stomach cancer mortality is also affected by public-sector healthcare spending. Initiatives that bolster employment and maintain public-sector healthcare expenditure may help to minimize increases in stomach cancer mortality during economic downturns.

Workplace bullying as an antecedent of mental health problems: a five-year prospective and representative study.

The present study investigates the proposed long-term relationship between exposure to workplace bullying and subsequent mental health in the form of anxiety and depression with a time lag of 5 years, exploring potential gender differences in these relationships. The study employs a prospective design with a 5-year time lag in a representative sample of the Norwegian workforce. A cohort of 1,613 employees reported on their exposure to workplace bullying and their symptoms of anxiety and depression at both measurement times. The results showed exposure to workplace bullying to be a significant predictor of mental health problems 5 years on, even after controlling for baseline mental health status, gender, age, job-change, job demands and job control, yet for men only. Baseline levels of mental health problems in terms of symptoms of anxiety and depression did not predict subsequent exposure to bullying at follow-up among women, but anxiety did in the case of men. Workplace bullying poses a serious long-term threat to the health and well-being of workers, at least for men. The results of the study pinpoint the need for mental health treatment as well as for preventive measures in relation to workplace bullying, and pinpoint the need for a gender perspective in these studies.

The treatment of chronic laxities of the ankle by external ligament tension restoration

Chronic external laxities of ankle have long been treated by plasties with the short peroneal as stabilizer of the hindfoot. The restoration of the tension of the internal external capsule–ligament complex with a subastragalus flap is an interesting solution. Thirty-two sporting patients with an external instability of the ankle were treated surgically by restoration of the tension of the external lateral ligament using the Saragaglia technique and were re-examined with an average 5-year time lag. The instability and the anterior drawer were measured in pre and post-operative periods. If the intervention gives good results in severe external laxities, the result is definitely less good in laxities of low importance. The presence of a functional disorder of the forefoot constituted in the series a pejorative factor. The intervention makes it possible to correct external instability of the tibiotalar and subastragalus. The conservation of the axis of the hindfoot is useful for a good performance because an instability of the subastragalus deteriorates the result of the intervention.

Accessibility to air travel correlates strongly with increasing melanoma incidence*

As the cost of air travel has decreased substantially in the USA and Europe over the past few decades, leisure travel to vacation destinations during the winter months has expanded significantly. This trend has probably increased the incidence of significant ultraviolet radiation exposure and sunburn in a broader population who could not previously afford this kind of travel. The purpose of this study was to analyse the correlation between increasing accessibility to air travel and melanoma incidence. This ecological study surveyed air travel patterns and melanoma incidence over the past three decades. Melanoma age-adjusted incidence was obtained from the United States Surveillance, Epidemiology, and End Results 9 Registry Database, 1975-2000, and the Cancer Registry of Norway, 1965-2000. United States mean inflation-adjusted airfare prices for four airports linked to leisure destinations (Miami, Los Angeles, San Diego, Phoenix) were compared with melanoma incidence. Parallel analyses were performed using annual domestic passenger-kilometres and melanoma incidence in Norway. Declining United States leisure-specific airfares corresponded strongly with increasing melanoma incidence (r = 0.96, r = 0.92, P < 0.001). Modelling a 5-year time lag between airfare and melanoma diagnosis strengthened the association (r = 0.98, r = 0.96, P < 0.001). Longer time lags could not be modelled due to data limitations. Data from Norway similarly showed that increasing air passenger mileage corresponded strongly with increasing melanoma incidence. Although correlation does not equate to causality, the very strong relationship between increasing access to air travel and melanoma incidence suggests that changes in recreational patterns may be contributing significantly to the public health problem of melanoma.

Comparing Risks and Benefits of Colorectal Cancer Screening in Elderly Patients

In patients with limited life expectancy, the risks of colorectal cancer screening may outweigh the benefits. The aim of this study was to quantify risks and benefits of different screening strategies in elderly patients with varying life expectancies. We examined risks and benefits of screening in patients aged 70-94 years with differing health status using 3 strategies: annual fecal occult blood tests, flexible sigmoidoscopy every 5 years, or colonoscopy every 10 years. We compared the number needed to screen to prevent one cancer-related death and the number needed to encounter one screening-related complication for different strategies. The potential benefit from screening varied widely with age, life expectancy, and screening modality. One cancer-related death would be prevented by screening 42 healthy men aged 70-74 years with colonoscopy, 178 healthy women aged 70-74 years with fecal occult blood tests, 431 women aged 75-79 years in poor health with colonoscopy, or 945 men aged 80-84 years in average health with fecal occult blood tests. Colonoscopy screening had the greatest benefit but the highest risk of complications. The potential for screening-related complications was greater than estimated benefit in some population subgroups aged 70 years and older. At all ages and life expectancies, the potential reduction in mortality from screening outweighed the risk of colonoscopy-related death. The potential benefits and risks of screening vary in elderly patients of different life expectancies. For any individual patient, the potential for harm from screening must be weighed against the likelihood of benefit, especially with shorter life expectancy.

Do trends in population levels of blood pressure and other cardiovascular risk factors explain trends in stroke event rates? Comparisons of 15 populations in 9 countries within the WHO MONICA Stroke Project. World Health Organization Monitoring of Trends and Determinants in Cardiovascular Disease.

Previous studies have indicated a reasonably strong relationship between secular trends in classic cardiovascular risk factors and stroke incidence within single populations. To what extent variations in stroke trends between populations can be attributed to differences in classic cardiovascular risk factor trends is unknown. In the World Health Organization Monitoring of Trends and Determinants in Cardiovascular Disease (WHO MONICA) Project, repeated population surveys of cardiovascular risk factors and continuous monitoring of stroke events have been conducted in 35- to 64-year-old people over a 7- to 13-year period in 15 populations in 9 countries. Stroke trends were compared with trends in individual risk factors and their combinations. A 3- to 4-year time lag between changes in risk factors and change in stroke rates was considered. Population-level trends in systolic blood pressure showed a strong association with stroke event trends in women, but there was no association in men. In women, 38% of the variation in stroke event trends was explained by changes in systolic blood pressure when the 3- to 4-year time lag was taken into account. Combining trends in systolic blood pressure, daily cigarette smoking, serum cholesterol, and body mass index into a risk score explained only a small fraction of the variation in stroke event trends. In this study, it appears that variations in stroke trends between populations can be explained only in part by changes in classic cardiovascular risk factors. The associations between risk factor trends and stroke trends are stronger for women than for men.

Estimation of contribution of changes in classic risk factors to trends in coronary-event rates across the WHO MONICA Project populations

From the mid-1980s to mid-1990s, the WHO MONICA Project monitored coronary events and classic risk factors for coronary heart disease (CHD) in 38 populations from 21 countries. We assessed the extent to which changes in these risk factors explain the variation in the trends in coronary-event rates across the populations. In men and women aged 35-64 years, non-fatal myocardial infarction and coronary deaths were registered continuously to assess trends in rates of coronary events. We carried out population surveys to estimate trends in risk factors. Trends in event rates were regressed on trends in risk score and in individual risk factors. Smoking rates decreased in most male populations but trends were mixed in women; mean blood pressures and cholesterol concentrations decreased, bodymass index increased, and overall risk scores and coronary-event rates decreased. The model of trends in 10-year coronary-event rates against risk scores and single risk factors showed a poor fit, but this was improved with a 4-year time lag for coronary events. The explanatory power of the analyses was limited by imprecision of the estimates and homogeneity of trends in the study populations. Changes in the classic risk factors seem to partly explain the variation in population trends in CHD. Residual variance is attributable to difficulties in measurement and analysis, including time lag, and to factors that were not included, such as medical interventions. The results support prevention policies based on the classic risk factors but suggest potential for prevention beyond these.

Organizational Learning in Cooperative Alliances: Some Case Studies in Biotechnology

Dedicated biotechnology firms (DBFs) have played an important role in commercializing biotechnology. They emerged first in the US and, after a 5-year time lag, they also appeared in Europe. Faced with long and costly product lead times, DBFs raised money by entering into research contracts, mainly with large chemical and pharmaceutical companies. These coopertive research alliances have not vanished as biotechnology has matured and are more in evidence today than they were in the early dasy of the commercialization of biotechnology. This paper investigates how and why large and small companies enter research collaborations, what they learn from working together, and the effects on European competitiveness.

Validation of Lake Whitefish Catch-Per-Unit-Effort Data with Time Series Analysis

Catch-per-unit-effort (CPUE) data for lake whitefish Coregonus clupeaformis in Michigan waters of Lake Huron were examined with time analysis to test if they can describe the abundance of lake whitefish. Relations between lake whitefish CPUE and environmental and biological data were investigated with cross-correlation analysis. A 4-year time lag, corresponding to the age at maturity, was found for lake whitefish CPUE. Cross-correlation analysis indicated that lake whitefish CPUE was negatively correlated with monthly air temperatures and abundance of sea lamprey Petromyzon marinus in previous years, and CPUE was positively correlated with fishing effort 1 year later. The results indicated that fishermen track lake whitefish abundance and that CPUE can describe fluctuations of the lake whitefish population.