scholarly journals Changes in the reproductive parameters of female harp seals (Pagophilus groenlandicus) in the Northwest Atlantic

2009 ◽  
Vol 67 (2) ◽  
pp. 304-315 ◽  
Author(s):  
Becky Sjare ◽  
Garry B. Stenson
Keyword(s):  
Environmental Factors ◽  
Population Size ◽  
Sexual Maturity ◽  
Reproductive Parameters ◽  
Northwest Atlantic ◽  
Pagophilus Groenlandicus ◽  
Long Term Trends ◽  
The Mean ◽  
The 1950S

Abstract Sjare, B., and Stenson, G. B. 2010. Changes in the reproductive parameters of female harp seals (Pagophilus groenlandicus) in the Northwest Atlantic. – ICES Journal of Marine Science, 67: 304–315. Changes in female harp seal (Pagophilus groenlandicus) reproductive parameters from 1980 to 2004, and long-term trends since the early 1950s, are evaluated. Estimates of the total number of seals in the Northwest Atlantic declined from ∼3.0 million in the 1950s to 1.8 million in the early 1970s, then increased steadily to 5.5 million in 1996, at which relatively stable level it has remained since. Pregnancy rates increased from ∼86% in the 1950s to a high of 98% in the mid-1960s, then declined to ∼65–70% by the early 1990s; the rate then varied between 45 and 70% from 2000 to 2004. Concurrently, the mean age at sexual maturity decreased from 5.8 (s.e = 0.02) years in the mid-1950s to 4.1 (s.e. = 0.02) in the late 1970s, increased to 5.5 (s.e. = 0.03) years by the early 1990s, and peaked at 5.7 (s.e. = 0.01) in 1995. From 2000 to 2004, mean age varied from 4.9 (s.e. = 0.01) to 6.0 (s.e. = 0.01) years. Although the direction of change in each of the parameters was consistent with a density-dependent response, changes in population size explained relatively little of the variability observed, suggesting that other ecological or environmental factors were influential.

scholarly journals Different long-term trends of the oxygen red 630.0 nm line nightglow intensity as the result of lowering the ionosphere F2 layer

2008 ◽  
Vol 26 (8) ◽  
pp. 2069-2080 ◽  
Author(s):  
N. B. Gudadze ◽  
G. G. Didebulidze ◽  
L. N. Lomidze ◽  
G. Sh. Javakhishvili ◽  
M. A. Marsagishvili ◽  
...  
Keyword(s):  
Electron Density ◽  
Line Intensity ◽  
Peak Height ◽  
Height Distribution ◽  
Theoretical Simulation ◽  
Type Layer ◽  
Long Term Trends ◽  
The Mean ◽  
Long Term Trend

Abstract. Long-term observations of total nightglow intensity of the atomic oxygen red 630.0 nm line at Abastumani (41.75° N, 42.82° E) in 1957–1993 and measurements of the ionosphere F2 layer parameters from the Tbilisi ionosphere station (41.65° N, 44.75° E) in 1963–1986 have been analyzed. It is shown that a decrease in the long-term trend of the mean annual red 630.0 nm line intensity from the pre-midnight value (+0.770±1.045 R/year) to its minimum negative value (−1.080±0.670 R/year) at the midnight/after midnight is a possible result of the observed lowering of the peak height of the ionosphere F2 layer electron density hmF2 (−0.455±0.343 km/year). A theoretical simulation is carried out using a simple Chapman-type layer (damping in time) for the height distribution of the F2 layer electron density. The estimated values of the lowering in the hmF2, the increase in the red line intensity at pre-midnight and its decrease at midnight/after midnight are close to their observational ones, when a negative trend in the total neutral density of the upper atmosphere and an increase in the mean northward wind (or its possible consequence – a decrease in the southward one) are assumed.

Production, Mortality, And Sustainable Yield Of Northwest Atlantic Harp Seals (Pagophilus groenlandicus)

1978 ◽  
Vol 35 (9) ◽  
pp. 1249-1261 ◽  
Author(s):  
G. H. Winters
Keyword(s):  
Population Size ◽  
Total Population ◽  
Historical Data ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Natural Mortality ◽  
Northwest Atlantic ◽  
The Past ◽  
Relative Contribution ◽  
Pagophilus Groenlandicus

From recent and historical data the natural mortality rate of adult harp seals (Pagophilus groenlandicus) is estimated to be 0.10 which is within the range of previous estimates (0.08–0.11). New estimates of bedlamer and 0-group natural mortality rates were not significantly different from those of adult seals. Pup production estimates from survival indices agreed well with those from sequential population analyses and indicated a decline from about 350 000 animals in the early 1950s to about 310 000 animals in the early 1970s. Over the same period the 1+ population size declined from 2.5 to 1.1 million animals but has been increasing at the rate of 3%/yr since the introduction of quotas in 1972. The relative contribution of the "Front" production to total ("Front" plus Gulf) production during the past decade has fluctuated from 49 to 87%, the average of 64% being very similar to the 61% obtained previously. These fluctuations suggest some interchange between "Front" and Gulf adults and it is concluded that homing in the breeding areas is a facultative rather than obligatory aspect of seal behavior. Thus the heavier exploitation of the "Front" production is probably sufficiently diffused into the total population to avoid serious effects on "Front" production. The maximum sustainable yield of Northwest Atlantic seals harvested according to recent patterns is estimated to be 290 000 animals (80% pups) from a 1+ population size of 1.8 million animals producing 460 000 pups annually. The sustainable yield at present levels of pup production (335 000 animals) is calculated to be 220 000 animals which is substantially above the present TAC of 180 000 animals and coincides with present harvesting strategies designed to enable the seal hunt to increase slowly towards the MSY level. Key words: mortality, production, sustainable yield, population dynamics, marine mammal

scholarly journals Reproductive Biology of Round Sardinella (Sardinella Aurita) (Valenciennes, 1847) in Senegalese Coastal Waters

2018 ◽  
Vol 9 (1) ◽  
pp. 31
Author(s):  
Ismaïla NDIAYE ◽  
Alassane SARR ◽  
Alioune FAYE ◽  
Modou THIAW ◽  
Malick DIOUF ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Coastal Waters ◽  
Sexual Maturity ◽  
Reproductive Parameters ◽  
Monthly Variation ◽  
Relative Fecundity ◽  
The Mean ◽  
Sardinella Aurita ◽  
Somatic Index

In this study, a total of 1068 specimens Sardinella aurita of which 553 females and 515 males were examined. The objectif of this study was to determine the reproductive parameters of Sardinella aurita. The sex ratio was significantly in favor of females (55%). The size at first sexual maturity was estimated at 18.9 cm for females and 18.0 cm for males. The monthly variation of sexual maturity stages and gonado-somatic index (GSI) allowed to locate the reproduction periods from February to June and from September to December. The mean absolute fecundity was estimated at 110.794 ± 7582 oocytes whereas relative fecundity was about 422 ± 26 oocytes per gram of female.

scholarly journals Evolutionary dynamics of neutral phenotypes under DNA substitution models

2020 ◽  
Author(s):  
Shadi Zabad ◽  
Alan M Moses
Keyword(s):  
Dna Sequences ◽  
Evolutionary Dynamics ◽  
Gc Content ◽  
Stabilizing Selection ◽  
Restoring Force ◽  
Dna Substitution ◽  
Long Term Trends ◽  
The Mean ◽  
Molecular Phenotypes

AbstractWe study the evolution of quantitative molecular traits in the absence of selection. Using a simple theory based on Felsenstein’s 1981 DNA substitution model, we predict a linear restoring force on the mean of an additive phenotype. Remarkably, the mean dynamics are independent of the effect sizes and genotype and are similar to the widely-used OU model for stabilizing selection. We confirm the predictions empirically using additive molecular phenotypes calculated from ancestral reconstructions of putatively unconstrained DNA sequences in primate genomes. We show that the OU model is favoured by inference software even when applied to GC content of unconstrained sequences or simulations of DNA evolution. We predict and confirm empirically that the dynamics of the variance are more complicated than those predicted by the OU model, and show that our results for the restoring force of mutation hold even for non-additive phenotypes, such as number of transcription factor binding sites, longest encoded peptide and folding propensity of the encoded peptide. Our results have implications for efforts to infer selection based on quantitative phenotype dynamics as well as to understand long-term trends in evolution of quantitative molecular traits.

Assessment of Nonresearch Industry Payments to Otolaryngologists in 2014 and 2015

2018 ◽  
Vol 158 (6) ◽  
pp. 1028-1034 ◽  
Author(s):  
Neil Pathak ◽  
Rance J. T. Fujiwara ◽  
Saral Mehra
Keyword(s):  
Annual Variation ◽  
Public Awareness ◽  
Large Change ◽  
Cross Sectional ◽  
Food And Beverage ◽  
Long Term Trends ◽  
The Mean ◽  
Open Payments ◽  
Made In

Objective To characterize, describe, and compare nonresearch industry payments made to otolaryngologists in 2014 and 2015. Additionally, to describe industry payment variation within otolaryngology and among other surgical specialties. Study Design Retrospective cross-sectional database analysis. Setting Open Payments Database. Subjects and Methods Nonresearch payments made to US otolaryngologists were characterized and compared by payment amount, nature of payment, sponsor, and census region between 2014 and 2015. Payments in otolaryngology were compared with those in other surgical specialties. Results From 2014 to 2015, there was an increase in the number of compensated otolaryngologists (7903 vs 7946) and in the mean payment per compensated otolaryngologist ($1096 vs $1242), as well as a decrease in the median payment per compensated otolaryngologist ($169 vs $165, P = .274). Approximately 90% of total payments made in both years were attributed to food and beverage. Northeast census region otolaryngologists received the highest median payment in 2014 and 2015. Compared with other surgical specialists, otolaryngologists received the lowest mean payment in 2014 and 2015 and the second-lowest and lowest median payment in 2014 and 2015, respectively. Conclusion The increase in the mean payment and number of compensated otolaryngologists can be explained by normal annual variation, stronger industry-otolaryngologist relationships, or improved reporting; additional years of data and improved public awareness of the Sunshine Act will facilitate determining long-term trends. The large change in disparity between the mean and median from 2014 to 2015 suggests greater payment variation. Otolaryngologists continue to demonstrate limited industry ties when compared with other surgical specialists.

Trends in match injury risk in professional male rugby union: a 16-season review of 10 851 match injuries in the English Premiership (2002–2019): the Professional Rugby Injury Surveillance Project

2020 ◽  
pp. bjsports-2020-102529
Author(s):  
Stephen W West ◽  
Lindsay Starling ◽  
Simon Kemp ◽  
Sean Williams ◽  
Matthew Cross ◽  
...  
Keyword(s):  
Injury Risk ◽  
Injury Severity ◽  
Rugby Union ◽  
Injury Surveillance ◽  
Injury Incidence ◽  
Match Play ◽  
Common Activity ◽  
Long Term Trends ◽  
The Mean

ObjectivesThe Professional Rugby Injury Surveillance Project is the largest and longest running rugby union injury surveillance project globally and focuses on the highest level of rugby in England.MethodsWe examined match injuries in professional men’s rugby over the period 2002/2003 to 2018/2019 and described trends in injuries over this time.ResultsOver the period 2002/2003–2018/2019, 10 851 injuries occurred in 1 24 952 hours of match play, equating to a mean of 57 injuries per club per season and one injury per team per match. The mean incidence, severity (days absence) and burden (days absence/1000 hours) of injury were 87/1000 hours (95% CI 82 to 92), 25 days (95% CI 22 to 28) and 2178 days/1000 hours (95% CI 1872 to 2484), respectively. The tackle accounted for 43% injuries with running the second most common activity during injury (12%). The most common injury location was the head/face with an incidence of 11.3/1000 hours, while the location with the highest overall burden was the knee (11.1 days/1000 hours). Long-term trends demonstrated stable injury incidence and proportion of injured players, but an increase in the mean and median severity of injuries. Concussion incidence, severity and burden increased from the 2009/2010 season onwards and from 2011 to 2019 concussion was the most common injury.ConclusionThe rise in overall injury severity and concussion incidence are the most significant findings from this work and demonstrate the need for continued efforts to reduce concussion risk as well as a greater understanding of changes in injury severity over time.

scholarly journals The Impact of Improved Thermistor Calibration on the Expendable Bathythermograph Profile Data

2017 ◽  
Vol 34 (9) ◽  
pp. 1947-1961 ◽  
Author(s):  
Marlos Goes ◽  
Elizabeth Babcock ◽  
Francis Bringas ◽  
Peter Ortner ◽  
Gustavo Goni
Keyword(s):  
Small Sample Size ◽  
Heat Content ◽  
Small Sample ◽  
Profile Data ◽  
Expendable Bathythermograph ◽  
Different Types ◽  
Long Term Trends ◽  
The Mean ◽  
The Impact

AbstractExpendable bathythermograph (XBT) data provide one of the longest available records of upper-ocean temperature. However, temperature and depth biases in XBT data adversely affect estimates of long-term trends of ocean heat content and, to a lesser extent, estimates of volume and heat transport in the ocean. Several corrections have been proposed to overcome historical biases in XBT data, which rely on constantly monitoring these biases. This paper provides an analysis of data collected during three recent hydrographic cruises that utilized different types of probes, and examines methods to reduce temperature and depth biases by improving the thermistor calibration and reducing the mass variability of the XBT probes.The results obtained show that the use of individual thermistor calibration in XBT probes is the most effective calibration to decrease the thermal bias, improving the mean thermal bias to less than 0.02°C and its tolerance from 0.1° to 0.03°C. The temperature variance of probes with screened thermistors is significantly reduced by approximately 60% in comparison to standard probes. On the other hand, probes with a tighter weight tolerance did not show statistically significant reductions in the spread of depth biases, possibly because of the small sample size or the sensitivity of the depth accuracy to other causes affecting the analysis.

Reproductive Rates of Harp Seals, Pagophilus groenlandicus (Erxleben)

1966 ◽  
Vol 23 (5) ◽  
pp. 757-766 ◽  
Author(s):  
D. E. Sergeant
Keyword(s):  
Sexual Maturity ◽  
Reproductive Rate ◽  
First Year ◽  
Published Data ◽  
Age Class ◽  
Adult Females ◽  
Pagophilus Groenlandicus ◽  
The Mean ◽  
Reproductive Rates ◽  
Lower Population

In less than a decade the mean age at sexual maturity of female harp seals of the Front, or northeastern Newfoundland population, decreased to 4 from [Formula: see text] years. Exploitation was heavy during this period and included a high proportion of seals older than 1 year. Females of the Gulf of St. Lawrence herd declined in mean age at sexual maturity over the same decade to 5 from nearly 6 years. Exploitation of this herd was lower, especially for animals older than their first year. Fertility of the adult females was likely higher in the more heavily exploited population. Published data on the White Sea population, which was reduced to low numbers, show reproduction at a lower mean age than for the present Front herd; for the Jan Mayen herd, of uncertain population status, about the same reproductive rate as the present Gulf herd. In most of the populations, samples of adult, whelped females showed the greatest number in the age-class about 1 year older than that first showing 100% of the females mature, as would be expected; however, samples from the Front herd showed dominance of an older age-class, suggesting that young adult females may to some extent segregate into separate groups. The immediate factors leading to increased reproductive rates at lower population densities were not elucidated.

Continuous Plankton Records: Annual Fluctuations of the Plankton in the Western English Channel, 1958–83

1986 ◽  
Vol 66 (4) ◽  
pp. 791-802 ◽  
Author(s):  
G. A. Robinson ◽  
H. G. Hunt
Keyword(s):  
Environmental Factors ◽  
Principal Component ◽  
Current Strength ◽  
English Channel ◽  
Long Term Trends ◽  
Temperature Radiation ◽  
Complex Relationships ◽  
Physical Elements ◽  
The Relationship

Surveys of the plankton at a depth of 10 m in the western English Channel have been carried out at monthly intervals from 1958 onwards using Continuous Plankton Recorders to provide data on annual fluctuations in abundance of the plankton. Interpretation of these results has been attempted by empirical associations with environmental factors (salinity, sea-surface temperature, radiation, atmospheric pressure patterns, wind speed and current strength). Principal component analysis has been used to extract the main patterns of change and correlation analysis for assessing the relationship between the plankton and the environmental factors. There are complex relationships between the plankton and all environmental factors, supporting previous conclusions that the long-term changes are mediated through interaction between the plankton and the climate. Spectral analysis showed long-term trends and shorter cycles of six and three to four years in both the biological and physical elements, indicating that changes in the western Channel are responding to changes in climate over a much wider area

scholarly journals Shift of subtropical transport barriers explains observed hemispheric asymmetry of decadal trends of age of air

2017 ◽  
Author(s):  
Gabriele P. Stiller ◽  
Federico Fierli ◽  
Felix Ploeger ◽  
Chiara Cagnazzo ◽  
Bernd Funke ◽  
...  
Keyword(s):  
Circulation Pattern ◽  
Transport Time ◽  
Model Calculations ◽  
Model Predictions ◽  
Southward Shift ◽  
Transport Barriers ◽  
Long Term Trends ◽  
The Mean ◽  
Middle Stratosphere

Abstract. In response to global warming the Brewer–Dobson circulation in the stratosphere is expected to accelerate and the mean transport time of air along this circulation to decrease. This would imply a negative stratospheric age of air trend, i.e. an air parcel would need less time to travel from the tropopause to any point in the stratosphere. Age of air as inferred from tracer observations, however, shows zero to positive trends in the Northern midlatitude stratosphere and zonally asymmetric patterns. Using satellite 5 observations and model calculations we show that the observed latitudinal and vertical patterns of the decadal changes of age of air in the lower to middle stratosphere during 2002–2012 are predominantly caused by a southward shift of the circulation pattern of about 5 degrees. After correction for this shift, the observations reveal a hemispherically almost symmetric decrease of age of air in the lower to middle stratosphere up to 800 K of up to −0.25 years over the 2002–2012 period with strongest decrease in the Northern tropics. This net change is consistent with long-term trends from model predictions.

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