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This study investigates survival and abundance of killer whales ( Orcinus orca ) in Norway in 1988-2019 using capture-recapture models of photo-identification data. We merged two datasets collected in a restricted fjord system in 1988-2008 (Period 1) with a third, collected after their preferred herring prey shifted its wintering grounds to more exposed coastal waters in 2012-2019 (Period 2), and investigated any differences between these two periods. The resulting dataset, spanning 32 years, comprised 3284 captures of 1236 whales, including 148 individuals seen in both periods. The best-supported models of survival included the effects of sex and time period, and the presence of transients (whales seen only once). Period 2 had a much larger percentage of transients compared to Period 1 (mean = 30% vs. 5%) and the identification of two groups of whales with different residency patterns revealed heterogeneity in recapture probabilities. This caused estimates of survival rates to be biased downward (females: 0.955 ± 0.027 SE, males: 0.864 ± 0.038 SE) compared to Period 1 (females: 0.998 ± 0.002 SE, males: 0.985 ± 0.009 SE). Accounting for this heterogeneity resulted in estimates of apparent survival close to unity for regularly seen whales in Period 2. A robust design model for Period 2 further supported random temporary emigration at an estimated annual probability of 0.148 (± 0.095 SE). This same model estimated a peak in annual abundance in 2015 at 1061 individuals (95% CI 999-1127), compared to a maximum of 731 (95% CI 505-1059) previously estimated in Period 1, and dropped to 513 (95% CI 488-540) in 2018. Our results indicate variations in the proportion of killer whales present of an undefined population (or populations) in a larger geographical region. Killer whales have adjusted their distribution to shifts in key prey resources, indicating potential to adapt to rapidly changing marine ecosystems., Competing Interests: Authors have no competing interests to declare., (© 2021 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

Purpose: We examined oral health behaviour and its association with school achievement among Finnish adolescents., Materials and Methods: This study is part of the Finnish national School Health Promotion study (SHP). The study population comprised a representative sample of Finnish 15-year-olds (N = 45,877). A questionnaire inquired about the respondents' school achievements and health habits (toothbrushing, smoking), background factors (age, gender, school type, family structure), and their parents' background factors (education, smoking). Chi-square tests and logistic regression models were used in the statistical analyses., Results: Better school achievements were associated with better oral health behaviour: 73.1% of students with the highest mean grades (9-10) brushed their teeth twice daily, compared to 33.8% of those with the lowest mean grade (6.9 or less). The lowest mean grade was associated with brushing less than twice daily, especially among boys (odds ratios (OR) = 4.1; 95% CI 3.6-4.7) when compared to those with the highest mean grade, but also among girls (OR = 2.3; 95% CI 2.1-2.7). Smoking among boys was associated with poor oral hygiene (OR = 1.3; 95% CI 1.2-1.4)., Conclusion: School success is strongly associated with oral health behaviour among adolescents. Preventive treatment should be targeted especially at boys with poor school achievement and smoking behaviour.

Background: To assess associations between oral health behaviour and physical activity and related factors among adolescents., Methods: The study population (n = 76 529) consisted of a representative sample of 16- to 18-year-old Finnish adolescents (boys: 37 211, girls: 39 318). An anonymous, confidential and voluntary classroom-administered questionnaire included questions about tooth brushing frequency, physical activity, BMI and eating habits. Moderate-to-vigorous physical activity (MVPA) was used to assess the adolescents' physical activity. The chi-square test and multiple binary logistic regression were used for statistical analyses. Adjusted odds ratios (OR) and their 95% confidence intervals (CI) were calculated for MVPA, BMI, breakfast, smoking and socioeconomic factors as parents' education and school type., Results: The prevalence of twice daily tooth brushing was highest among adolescents reporting 4 hours or more of MVPA (51-77%). Obese and smoking adolescents exercised less often than normal weighted and non-smokers. Girls brushed their teeth twice daily significantly more often than boys (P < 0.001), and high-school students brushed their teeth significantly more often than vocational school students (P < 0.001). Logistic regression models showed that obesity (OR = 2.14, 95% CI 1.92-2.37) and irregular breakfast eating (OR = 2.35, 95% CI 2.19-2.52) among boys, and obesity (OR = 2.81, 95% CI 2.48-3.17), physical inactivity (OR = 1.89, 95% CI 1.78-2.00) and irregular breakfast eating (OR = 1.91, 95% CI 1.79-2.04) among girls were strong predictors for poor tooth brushing., Conclusions: Physically active adolescents had better oral health behaviour than less active adolescents. Obesity and smoking were associated with infrequent tooth brushing., (© The Author(s) 2018. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.)

Background: We examined the validity of self-reported number of teeth in middle-aged adults by using representative cohort data to compare corresponding self-reported and clinical values., Methods: This validity study is part of the representative 46-year-old follow-up of the Northern Finland Birth Cohort 1966 (NFBC1966) Study. Mailed questionnaires (n = 5950) requested information on self-reported number of teeth and background variables (education, tooth brushing and smoking), while clinical oral health examinations (n = 1891) assessed the number of teeth (the 'gold standard'). The main analyses compared the self-reported and clinical values for the number of teeth in 1669 participants. Scatterplot and Bland-Altman plot served for visual analyses, and alternative correlation coefficients (Pearson, Spearman, intraclass) for numerical comparisons separately for men and women, with stratification according to background variables., Results: The clinical assessment revealed that the mean value for the number of teeth was 27.46 (SD = 2.38), while the corresponding value based on self-reported information was 27.48 (SD = 2.78). According to the Bland-Altman plot, the mean difference between the clinical and self-reported values was - 0.02 (95% limits of agreement, LoA: - 3.37 to 3.32). The observed ranges of intraclass correlation coefficients (ICC) among men and women were 0.72 to 0.95 and 0.72 to 0.85, respectively, depending on the background variables., Conclusions: Self-reported number of teeth in middle-aged Finnish adults agreed closely with the corresponding clinical measure.

Aim: We investigated the association of impaired glucose metabolism with tooth loss in adults in the Northern Finland Birth Cohort Study 1966 (NFBC1966)., Methods: We examined 4394 participants from the 46-year follow-up of the NFBC1966. Self-reported number of teeth as well as insulin and glucose values, taken during a standard oral glucose tolerance test (OGTT), served as the primary study variables. A multinomial logistic regression model served to analyse (unadjusted, smoking-adjusted and fully adjusted) the association between number of teeth (0-24, 25-27, 28-32) and glucose metabolism in women and men., Results: Among women, type 2 diabetes - whether previously known or detected during screening - pointed to a higher likelihood of 0-24 teeth (fully adjusted OR = 2.99, 95%CI = 1.54-5.80) and 25-27 teeth (OR = 1.91, 95%CI = 1.18-3.08) than did normal glucose tolerance. Similarly, impaired fasting glucose and impaired glucose tolerance together indicated a higher likelihood of 0-24 teeth (OR = 1.71, 95%CI = 1.09-2.69) than did normal glucose tolerance. A similar, statistically non-significant, pattern emerged among men. Number of teeth associated with OGTT insulin and glucose curves as well as with the Matsuda index in both women and men., Conclusions: Tooth loss strongly associated with impaired glucose metabolism in middle-aged Finnish women., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Despite smoking cessation efforts, cigarette smoking remains a serious general and oral health problem. We aimed to investigate the putative benefits of smoking cessation on dentition and to analyse whether the time elapsed since smoking cessation associated positively with the remaining number of teeth., Methods: This cross-sectional study analyses data from the 46-year follow-up of the Northern Finland Birth Cohort Study 1966 (NFBC1966). A total of 5 540 subjects participated in this cross-sectional study, which utilises both clinical dental examinations and mailed questionnaires. We used the following information on smoking: status (current, former, never), years of smoking (current, former) and years elapsed since smoking cessation (former). Self-reported and clinically measured number of teeth (including third molars) served as alternative outcomes. We used binary logistic regression models to analyse the dichotomised number of teeth ('0-27', '28-32') and then calculated unadjusted and adjusted odds ratios (OR) with 95 % confidence intervals (CI) for the smoking variables (never smoker as the reference). Gender, education, tooth brushing frequency, diabetes and alcohol use served as confounders for the adjusted models., Results: Ten years or more of smoking associated with tooth loss; this effect was the strongest among men who reported having an ongoing smoking habit (self-reported outcome: adjusted OR = 1.74, CI = 1.40-2.16) and the weakest among women classified as former smokers (self-reported outcome: adjusted OR = 1.27, CI = 1.00-1.62)., Conclusions: This study shows that smoking has long-term effects on tooth loss even after cessation. The findings support smoking cessation efforts to reduce oral health risks.

Background: Smoking is a risk factor for oral diseases and tooth loss. Our aim was to analyze the association between smoking intensity and duration and tooth loss among middle-aged Finnish adults who have enjoyed access to subsidized dental care since childhood., Methods: This study was based on the Northern Finland Birth Cohort 1966 (NFBC1966) Project, a representative sample of Finnish 46-year-olds. Altogether 1946 46-year-olds participated in a survey and comprehensive clinical oral examinations. We measured smoking exposure in pack-years (intensity) and years of smoking (duration) combined with recent smoking status (current, former, occasional or never). We used negative binomial regression models to estimate the unadjusted and adjusted relative risks (RR) with corresponding 95 % confidence intervals (CI) for tooth loss as an outcome. Gender, education, tooth brushing frequency, dental plaque, diabetes and alcohol use served as explanatory variables for the adjusted models., Results: Smoking intensity associated with tooth loss in an exposure-dependent manner: those with a high number of pack-years had a significantly greater probability of tooth loss than never smokers: 11-20 pack-years (RR = 1.55, 95 % CI = 1.15-2.08) and 21 or more pack-years (RR = 1.78, 95 % CI = 1.36-2.33). Smoking duration also associated with tooth loss: those who had smoked for several years had a significantly higher probability of tooth loss than never smokers: 21-30 years of smoking (RR = 1.66, 95 % CI = 1.29-2.12) and 31 or more years of smoking (RR = 1.72, 95 % CI = 1.20-2.45)., Conclusions: We found a clear intensity- and duration-dependent relation between smoking and tooth loss among adults with access to subsidized dental care and in good oral health.

Population genetic structure of North Atlantic killer whale samples was resolved from differences in allele frequencies of 17 microsatellite loci, mtDNA control region haplotype frequencies and for a subset of samples, using complete mitogenome sequences. Three significantly differentiated populations were identified. Differentiation based on microsatellite allele frequencies was greater between the two allopatric populations than between the two pairs of partially sympatric populations. Spatial clustering of individuals within each of these populations overlaps with the distribution of particular prey resources: herring, mackerel and tuna, which each population has been seen predating. Phylogenetic analyses using complete mitogenomes suggested two populations could have resulted from single founding events and subsequent matrilineal expansion. The third population, which was sampled at lower latitudes and lower density, consisted of maternal lineages from three highly divergent clades. Pairwise population differentiation was greater for estimates based on mtDNA control region haplotype frequencies than for estimates based on microsatellite allele frequencies, and there were no mitogenome haplotypes shared among populations. This suggests low or no female migration and that gene flow was primarily male mediated when populations spatially and temporally overlap. These results demonstrate that genetic differentiation can arise through resource specialization in the absence of physical barriers to gene flow., (© 2010 Blackwell Publishing Ltd.)

Blubber tissue of one subadult and eight male adult killer whales was sampled in Northern Norway in order to assess the degree and type of contaminant exposure and transfer in the herring-killer whale link of the marine food web. A comprehensive selection of contaminants was targeted, with special attention to toxaphenes and polybrominated diphenyl ethers (PBDEs). In addition to assessing exposure and food chain transfer, selective accumulation and metabolism issues also were addressed. Average total polychlorinated biphenyl (PCB) and pesticide levels were similar, approximately 25 microg/g lipid, and PBDEs were approximately 0.5 microg/g. This makes killer whales one of the most polluted arctic animals, with levels exceeding those in polar bears. Comparing the contamination of the killer whale's diet with the diet of high-arctic species such as white whales reveals six to more than 20 times higher levels in the killer whale diet. The difference in contaminant pattern between killer whales and their prey and the metabolic index calculated suggested that these cetaceans have a relatively high capacity to metabolize contaminants. Polychlorinated biphenyls, chlordanes, and dichlorodiphenyldichloro-ethylene (DDE) accumulate to some degree in killer whales, although toxaphenes and PBDEs might be partly broken down.

Practical data analysis often encounters data sets with both relevant and useless variables. Supervised variable selection is the task of selecting the relevant variables based on some predefined criterion. We propose a robust method for this task. The user manually selects a set of target variables and trains a Self-Organizing Map with these data. This sets a criterion to variable selection and is an illustrative description of the user's problem, even for multivariate target data. The user also defines another set of variables that are potentially related to the problem. Our method returns a subset of these variables, which best corresponds to the description provided by the Self-Organizing Map and, thus, agrees with the user's understanding about the problem. The method is conceptually simple and, based on experiments, allows an accessible approach to supervised variable selection.

To date very little is still known about the acoustic behavior of Norwegian killer whales, in particular that of individual whales. In this study a unique opportunity was presented to document the sounds produced by five captured killer whales in the Vestfjord area, northern Norway. Individuals produced 14 discrete and 7 compound calls. Two call types were used both by individuals 16178 and 23365 suggesting that they may belong to the same pod. Comparisons with calls documented in Strager (1993) showed that none of the call types used by the captured individuals were present. The lack of these calls in the available literature suggests that call variability within individuals is likely to be large. This short note adds to our knowledge of the vocal repertoire of this population and demonstrates the need for further studies to provide behavioural context to these sounds.

Killer whales (Orcinus orca) feeding on herring (Clupea harengus) in a fjord in northern Norway were observed using underwater video. The whales cooperatively herded herring into tight schools close to the surface. During herding and feeding, killer whales swam around and under a school of herring, periodically lunging at it and stunning the herring by slapping them with the underside of their flukes while completely submerged. The kinematics of tail-slapping were analysed in detail. Tail-slaps were made up of a biphasic behaviour consisting of two phases with opposite angles of attack, a preparatory phase (negative angles of attack) and a slap phase (positive angles of attack). During the slap phase, the mean maximum angle of attack of the flukes was 47 degrees. The maximum speed of the flukes, measured at the notch, increased with whale length (L(w)) and was 2.2 L(w )s(-)(1), while the maximum acceleration of the flukes was size-independent and was 48 m s(-)(2). When killer whales slapped the herring successfully, disoriented herring appeared on the video at approximately the time of maximum fluke velocity, in synchrony with a loud noise. This noise was not heard when the tail-slaps 'missed' the target, suggesting that the herring were stunned by physical contact. Killer whales then ate the stunned herring one by one. Of the tail-slaps observed, 61 % were preceded by lunges into the school. We suggest that lunging was aimed at directing the school rather than at capturing the herring, since it occurred at a relatively low speed and there were no observations of the killer whales attempting to capture the herring during lunging behaviour. Given the high performance of the tail-slaps in terms of speed and acceleration, we suggest that tail-slapping by killer whales is a more efficient strategy of prey capture than whole-body attacks, since acceleration and manoeuvrability are likely to be poor in such large vertebrates.