scholarly journals Density surface fitting to estimate the abundance of humpback whales based on the NASS-95 and NASS- 2001 aerial and shipboard surveys

2009 ◽  
Vol 7 ◽  
pp. 143 ◽  
Author(s):  
Charles GM Paxton ◽  
M Louise Burt ◽  
Sharon L Hedley ◽  
Gísli A Víkingsson ◽  
Thorvaldur Gunnlaugsson ◽  
...  
Keyword(s):  
Confidence Intervals ◽  
Generalized Additive Models ◽  
Model Fitting ◽  
Humpback Whale ◽  
Additive Models ◽  
Humpback Whales ◽  
Bootstrap Sampling ◽  
Distance Analysis ◽  
The North ◽  
Abundance Estimates

Generalized additive models (GAMs) with spatially referenced covariates were fitted to data collected during the 1995 and 2001 Icelandic (shipboard and aerial) and Faroese (shipboard only) components of the North Atlantic Sightings Surveys (NASS-95 and NASS-2001). The shipboard surveys extended from the east coast of Greenland, around Iceland, down to an area along the west coast ofIreland (in 1995) and to the north of the United Kingdom (in 2001). In contrast, the aerial surveys were limited to Icelandic coastal waters only. The aim of the analysis was to predict density, and hence abundance, of humpback whales throughout the survey regions and also to establish if there was any evidence that humpback whale density was related to sea surface temperature or depth.Fitting GAMs to the 1995 data proved problematic and so various subsets of the data were used in an attempt to improve the model fitting. Such difficulties did not occur with the 2001 data. Confidence intervals (CIs) for the abundance estimates were estimated using bootstrap sampling methods.The estimated humpback whale abundance for the region covered by the aerial and shipboard surveys in 1995 was 10,521 (95% CI: 3,716–24,636) using all available data and 7,625 (3,641–22,424) if survey blocks with 0 sightings around the Faroes and south of 60˚ N where no humpback whales were detected were excluded from the analysis. The estimate for the total survey region in 2001 was 14,662 (9,441–29,879). The high upper bounds of the confidence intervals were thought to be caused by a paucity of effort over wide areas of the survey leading to interpolation. Overall, the uncertainty associated with these abundance estimates was approximately equal to, or greater than, that associated with a stratified distance analysis. Given these wide CIs the evidence for a substantial difference in abundance between years was equivocal. However there was evidence to suggest that humpback whales congregated in shallower waters between 6–8˚C.

Accounting for responsive movement in line transect estimates of abundance

2001 ◽  
Vol 58 (4) ◽  
pp. 777-787 ◽  
Author(s):  
D L Palka ◽  
P S Hammond
Keyword(s):  
Animal Movement ◽  
Generalized Additive Models ◽  
Radial Distance ◽  
Additive Models ◽  
Line Transect ◽  
The North ◽  
Minke Whales ◽  
Orientation Density ◽  
Using Data ◽  
Animal Orientation

A method is developed to account for effects of animal movement in response to sighting platforms in line transect density estimates using data on animal orientation. Models of expected distributions of animal orientation show that presence of responsive movement is determined by the ratio of animal sightings with angles of orientation in the third quadrant relative to the first quadrant. The distance at which response began is estimated using logistic generalized additive models of the relationship between radial distance and orientation. Density corrected for responsive movement is estimated by applying the Buckland and Turnock two-team analysis method to data poststratified into regions "close" to and "far" from (beyond the distance that responsive movement began) the observation platform instead of the original stratification by observation team. For data collected in the North Atlantic, white-sided dolphins, harbor porpoises, and minke whales responded by avoiding the survey ship, and white-beaked dolphins were attracted to the ship. For these populations, our method to correct for responsive movement gave significantly higher estimates, from 1.4 to 2.7 times the uncorrected estimates.

Errors in identification using natural markings: rates, sources, and effects on capture–recapture estimates of abundance

2001 ◽  
Vol 58 (9) ◽  
pp. 1861-1870 ◽  
Author(s):  
Peter T Stevick ◽  
Per J Palsbøll ◽  
Tim D Smith ◽  
Mark V Bravington ◽  
Philip S Hammond
Keyword(s):  
Error Rate ◽  
Large Scale ◽  
False Negative ◽  
Parametric Bootstrap ◽  
Humpback Whales ◽  
The North ◽  
Abundance Estimates ◽  
Capture Recapture ◽  
Quality Rating ◽  
Estimation Of Variance

The results of a double-marking experiment using natural markings and microsatellite genetic markers to identify humpback whales (Megaptera novaeangliae) confirm that natural markings are a reliable means of identifying individuals on a large scale. Of 1410 instances of double tagging, there were 414 resightings. No false positive and 14 false negative errors were identified. The rate of error increased with decreasing photographic quality; no errors were observed among photographs of the highest quality rating, whereas an error rate of 0.125 was identified in sightings for which only part of the area used for identification was visible. There was also a weaker relationship between error rate and the distinctiveness of markings, which may result from non-independence in coding for image quality and distinctiveness. A correction is developed for the Petersen two-sample abundance estimator to account for false negative errors in identification, and a parametric bootstrap procedure for estimation of variance is also developed. In application to abundance estimates from the North Atlantic, the correction reduces the bias in estimates made using poorer quality photographs to a negligible level while maintaining comparable precision.

Diel variation of stomach contents of North Sea cod (Gadus morhua) during a 24-h fishing survey: an analysis using generalized additive models

2000 ◽  
Vol 57 (12) ◽  
pp. 2363-2367 ◽  
Author(s):  
Sara A Adlerstein ◽  
Henny C Welleman
Keyword(s):  
North Sea ◽  
Stomach Content ◽  
Gadus Morhua ◽  
Generalized Additive Models ◽  
Stomach Contents ◽  
Additive Models ◽  
Large Prey ◽  
Diel Variation ◽  
The North ◽  
The North Sea

Results show that the weight of cod (Gadus morhua) stomach contents sampled in the North Sea varies significantly within 24 h. To determine whether feeding varied with time, over 1100 cod stomachs were collected around the clock between 7 and 18 May 1984 in two areas in the central North Sea thought to be representative for feeding studies. Here we investigate temporal feeding patterns based on the analysis of stomach-content data, using generalized additive models (GAMs). Results show significant variation of content weight and indicate morning and evening peaks. The relative peak importance differed between and within areas. We propose that differences are due to diet composition, namely, prey size and diel availability. Cod fed primarily on molluscs, mainly ocean quahog (Cyprina islandica), crustaceans, sandeels (Ammodytes spp.), haddock (Melanogrammus aeglefinus), herring (Clupea harrengus), and several flatfish species. In one area, the diet was dominated by fish, relatively large prey that perform diel vertical migration, and in the other by invertebrates, smaller prey that are digested faster. The diel pattern was more pronounced where invertebrate prey were dominant. Generalisation of results and implications for predation-mortality estimates based on data from the North Sea Stomach Content Database, used to implement multispecies models in the region, are discussed.

scholarly journals Association Between Waist Circumference and the Prevalence of (Pre) Hypertension Among 27,894 US Adults

2021 ◽  
Vol 8 ◽  
Author(s):  
Jin-Yu Sun ◽  
Yang Hua ◽  
Hua-Yi-Yang Zou ◽  
Qiang Qu ◽  
Yue Yuan ◽  
...  
Keyword(s):  
Waist Circumference ◽  
Confidence Intervals ◽  
Generalized Additive Models ◽  
Young Group ◽  
Cubic Spline ◽  
Normal Weight ◽  
Additive Models ◽  
Trend Test ◽  
Odds Ratios ◽  
Cross Sectional

Aims: This study aimed to investigate the association between waist circumference and the prevalence of (pre) hypertension.Methods: Cross-sectional data from the 2007–2018 National Health and Nutrition Examination Survey were analyzed. The historical trend of abdominal obesity was assessed by the Cochran–Armitage trend test. After preprocessed by the multiple imputation strategy, we used generalized additive models to assess the association of waist circumference with systolic/diastolic blood pressure and performed correlation analysis by the Spearman correlation coefficient. Moreover, we used multivariable logistic regression (non-adjusted, minimally adjusted, and fully adjusted models), restricted cubic spline, and sensitivity analysis to investigate the association between waist circumference and (pre) hypertension.Results: A total of 27,894 participants were included in this study. In the fully adjusted model, waist circumference was positively associated with (pre) hypertension with odds ratios (95% confidence intervals) of 1.28 (1.18–1.40) in the young group and 1.23 (1.15–1.33) in the old group. Restricted cubic spline showed a higher prevalence of (pre) hypertension with the increase of waist circumference. In the subgroup analysis, waist circumference showed a robust trend across all BMI categories with odds ratios (95% confidence intervals) of 3.33 (1.29–8.85), 1.35 (1.17–1.57), 1.27 (1.13–1.41), and 1.09 (1.01–1.17) in underweight, normal weight, overweight, and obese individuals, respectively.Conclusion: This study highlighted waist circumference as a significant biomarker to evaluate the risk of (pre) hypertension. Our results supported the measure of waist circumference regardless of BMI when evaluating the cardiometabolic risk related to fat distribution.

scholarly journals Fishers and whales in Iceland

2022 ◽  
Vol 22 (1) ◽  
pp. 111-128
Author(s):  
Charla J. Basran ◽  
Marianne H. Rasmussen
Keyword(s):  
Best Management Practices ◽  
Management Practices ◽  
Humpback Whale ◽  
Fishing Effort ◽  
Humpback Whales ◽  
Mitigation Measures ◽  
Fishing Gear ◽  
The North ◽  
New Information ◽  
Feeding Habitat

In Iceland, as in many places globally, the detrimental impacts of whale interactions with fishing gear on both fisheries and whales are not well understood and managed. This study conducted anonymous questionnaires of Icelandic fishers and interviews of capelin purse seine boat captains to gather first-hand knowledge of the issues fishers face due to whale interaction with their fishing gear. Results suggest that the humpback whale is the large whale species that is most often entangled or encircled in fishing gear and causing damage, however on occasion other large whale species are interacting with gear as well. Interactions between humpback whales and fishing gear appears to be primarily concentrated in the north/northeast and southwest of the country where there is high fishing effort and known humpback whale feeding habitat. Humpback whale interactions with gear occurred most often with capelin purse seines, which are targeting humpback whale prey, and data suggests that bycatch of whales in this fishery may be underreported. Damage and losses due to whale collisions with gear were reported to cost fishers up to 55.000.000ISK, suggesting this can be a costly issue for which mitigation measures should be explored. The use of acoustic “pingers” is one mitigation measure that has been previously tested by capelin purse-seiners and is something that captains indicated they would be interested in continuing to try. The creation of a whale entanglement/whale-gear interaction reporting system in Iceland would aid in gathering more data and quantifying how often these events are witnessed and what the consequences of these events are to both the fishers and the whales. This study provides new information about the consequences of large whale interactions with Icelandic fisheries and suggests that future collaboration with fishers can provide insight contributing to best management practices for sustainable fishing and whale conservation.

Spatial distribution analysis of the North Pacific spiny dogfish,Squalus suckleyi, in the North Pacific using generalized additive models

2017 ◽  
Vol 26 (6) ◽  
pp. 668-679 ◽  
Author(s):  
Toshikazu Yano ◽  
Seiji Ohshimo ◽  
Minoru Kanaiwa ◽  
Tsutomu Hattori ◽  
Masa-aki Fukuwaka ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
North Pacific ◽  
Generalized Additive Models ◽  
Additive Models ◽  
Spiny Dogfish ◽  
Distribution Analysis ◽  
The North ◽  
The North Pacific

scholarly journals Sardine potential habitat and environmental forcing off western Portugal

2010 ◽  
Vol 67 (8) ◽  
pp. 1553-1564 ◽  
Author(s):  
Juan P. Zwolinski ◽  
Paulo B. Oliveira ◽  
Victor Quintino ◽  
Yorgos Stratoudakis
Keyword(s):  
Chlorophyll A ◽  
Seasonal Pattern ◽  
Generalized Additive Models ◽  
Additive Models ◽  
Seasonal Effect ◽  
Oceanic Circulation ◽  
Environmental Forcing ◽  
Potential Habitat ◽  
The North ◽  
Spatio Temporal

Abstract Zwolinski, J. P., Oliveira, P. B., Quintino, V., and Stratoudakis, Y. 2010. Sardine potential habitat and environmental forcing off western Portugal. – ICES Journal of Marine Science, 67: 1553–1564. Relationships between sardine (Sardina pilchardus) distribution and the environment off western Portugal were explored using data from seven acoustic surveys (spring and autumn of 2000, 2001, 2005, and spring 2006). Four environmental variables (salinity, temperature, chlorophyll a, and acoustic epipelagic backscatter other than fish) were related to the acoustic presence and density of sardine. Univariate quotient analysis revealed sardine preferences for waters with high chlorophyll a content, low temperature and salinity, and low acoustic epipelagic backscatter. Generalized additive models depicted significant relationships between the environment and sardine presence but not with sardine density. Maps of sardine potential habitat (SPH) built upon the presence/absence models revealed a clear seasonal effect in the across-bathymetry and alongshelf extension of SPH off western Portugal. During autumn, SPH covered a large part of the northern Portuguese continental shelf but was almost absent from the southern region, whereas in spring SPH extended farther south but was reduced to a narrow band of shallow coastal waters in the north. This seasonal pattern agrees with the spatio-temporal variation of primary production and oceanic circulation described for the western Iberian shelf.

Spatial Analysis of Bering Sea Groundfish Survey Data Using Generalized Additive Models

1992 ◽  
Vol 49 (7) ◽  
pp. 1366-1378 ◽  
Author(s):  
Gordon Swartzman ◽  
Chisheng Huang ◽  
Stephen Kaluzny
Keyword(s):  
Survey Data ◽  
Bering Sea ◽  
Generalized Additive Models ◽  
Sampling Procedure ◽  
Additive Models ◽  
Trawl Survey ◽  
Flatfish Species ◽  
Eastern Bering Sea ◽  
Abundance Estimates ◽  
Average Abundance

Generalized additive models (GAM) are herein applied to trawl survey data in the eastern Bering Sea with an eye to (1) detecting trends in groundfish distributions and (2) improving abundance estimates by including the trend. GAM is a statistical method, analogous to regression, but without the assumptions of normality or linearity that relate a response variable (in this case, fish abundance) to location (latitude and longitude) and associated environmental variables (e.g. depth and bottom temperature). GAM provided reasonable (i.e. high r2) fits to the spatial distribution of five flatfish species and was able to define a spatial "signature" for each species, namely their preferred depth and temperature range. GAM also gave lower average abundance and abundance variability estimates for these five flatfish species than the stratified sampling procedure previously employed.

scholarly journals Statistical Approaches to Paternity Analysis in Natural Populations and Applications to the North Atlantic Humpback Whale

Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1673-1682 ◽  
Author(s):  
Rasmus Nielsen ◽  
David K Mattila ◽  
Philip J Clapham ◽  
Per J Palsbøll
Keyword(s):  
Reproductive Success ◽  
North Atlantic ◽  
Natural Populations ◽  
Genetic Data ◽  
Paternity Analysis ◽  
New Method ◽  
Humpback Whales ◽  
The North ◽  
Abundance Estimates ◽  
Sampling Fraction

Abstract We present a new method for paternity analysis in natural populations that is based on genotypic data that can take the sampling fraction of putative parents into account. The method allows paternity assignment to be performed in a decision theoretic framework. Simulations are performed to evaluate the utility and robustness of the method and to assess how many loci are necessary for reliable paternity inference. In addition we present a method for testing hypotheses regarding relative reproductive success of different ecologically or behaviorally defined groups as well as a new method for estimating the current population size of males from genotypic data. This method is an extension of the fractional paternity method to the case where only a proportion of all putative fathers have been sampled. It can also be applied to provide abundance estimates of the number of breeding males from genetic data. Throughout, the methods were applied to genotypic data collected from North Atlantic humpback whales (Megaptera novaeangliae) to test if the males that appear dominant during the mating season have a higher reproductive success than the subdominant males.

scholarly journals Factors associated with the spatial heterogeneity of COVID-19 in France: a nationwide ecological study

2020 ◽  
Author(s):  
Jean Gaudart ◽  
Jordi Landier ◽  
laetitia huiart ◽  
Eva Legendre ◽  
Laurent Lehot ◽  
...  
Keyword(s):  
Spatial Heterogeneity ◽  
Ecological Study ◽  
Generalized Additive Models ◽  
Principal Component ◽  
Additive Models ◽  
Factors Associated ◽  
North East ◽  
The North ◽  
Incidence And Mortality ◽  
The Impact

Like in many countries and regions, spread of the COVID 19 pandemic has exhibited important spatial heterogeneity across France, one of the most affected countries so far. To better understand factors associated with incidence, mortality and lethality heterogeneity across the 96 administrative departments of metropolitan France, we thus conducted a geoepidemiological analysis based on publicly available data, using hierarchical ascendant classification (HAC) on principal component analysis (PCA) of multidimensional variables, and multivariate analyses with generalized additive models (GAM). Our results confirm a marked spatial heterogeneity of in-hospital COVID 19 incidence and mortality, following the North East / South West diffusion of the epidemic. The delay elapsed between the first COVID-19 associated death and the onset of the national lockdown on March 17th, 2020, appeared positively associated with in-hospital incidence, mortality and lethality. Mortality was also strongly associated with incidence. Mortality and lethality rates were significantly higher in departments with older population, but they were not significantly associated with the number of intensive-care beds available in 2018. We did not find any significant association between incidence, mortality or lethality rates and incidence of new chloroquine and hydroxychloroquine dispensations in pharmacies either, nor between COVID 19 incidence and climate, nor between economic indicators and in-hospital COVID 19 incidence or mortality. This ecological study highlights the impact of population age structure, epidemic spread and transmission mitigation policies in COVID-19 morbidity or mortality heterogeneity.

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