scholarly journals Assessing natural mortality of Bay of Biscay anchovy from survey population and biomass estimates

2016 ◽  
Vol 73 (2) ◽  
pp. 216-234 ◽  
Author(s):  
Andrés Uriarte ◽  
Leire Ibaibarriaga ◽  
Lionel Pawlowski ◽  
Jacques Massé ◽  
Pierre Petitgas ◽  
...  
Keyword(s):  
Egg Production ◽  
Linear Models ◽  
Production Method ◽  
Natural Mortality ◽  
Bay Of Biscay ◽  
Stock Assessments ◽  
Long Time ◽  
Using Data ◽  
Log Linear ◽  
Firm Evidence

The closure of the anchovy (Engraulis encrasicolus) fishery in the Bay of Biscay between 2005 and 2010 because of low biomass levels provided an opportunity to estimate natural mortality using data from egg (daily egg production method, DEPM) and acoustic surveys implemented for the assessment of this population since 1987. Assuming that natural mortality (M) is constant over time and that catchability in both surveys is equal for all ages, M could be estimated using log-linear models on the series of surveys of population numbers at age and seasonal integrated stock assessments. The analysis suggests M values of around 0.9 for a common natural mortality at all ages. However, we found firm evidence that natural mortality at ages 2 and older (M2+) is markedly higher than at age 1 (M1), which indicates senescent mortality, a possibility suggested a long time ago for this type of short-lived species.

Educational Homogamy Among Married and Unmarried Couples in Europe

2008 ◽  
Vol 30 (1) ◽  
pp. 28-52 ◽  
Author(s):  
Dana Hamplova
Keyword(s):  
Linear Models ◽  
Married Couples ◽  
European Social Survey ◽  
Social Survey ◽  
Educational Homogamy ◽  
Educational Barriers ◽  
Educational Groups ◽  
Institutional Contexts ◽  
Using Data ◽  
Log Linear

In this article, educational homogamy among married and cohabiting couples in selected European countries is examined. Using data from two waves (2002 and 2004) of the European Social Survey, this article compares three cultural and institutional contexts that differ in terms of institutionalization of cohabitation. Evidence from log-linear models yields two main conclusions. First, as cohabitation becomes more common in society, marriage and cohabitation become more similar with respect to partner selection. Second, where married and unmarried unions differ in terms of educational homogamy, married couples have higher odds of overcoming educational barriers (i.e., intermarrying with other educational groups).

scholarly journals DEVELOPMENT STAGE, AGEING AND NATURAL MORTALITY OF ANCHOVY EGGS (Encrasicholina SPECIES) FROM BACAN

2017 ◽  
Vol 4 (2) ◽  
pp. 52
Author(s):  
Retno Andamari ◽  
Andriko N. Susanto ◽  
David A. Milton
Keyword(s):  
Egg Production ◽  
Production Method ◽  
Development Stage ◽  
Large Series ◽  
Natural Mortality

ln order to study the possible application of the Daily Egg Production Method (DEPM) for estimating anchovy (Encrasicholina spp.) biomass at Bacan. Maluku, we collected a large series of plankton samples.

scholarly journals Are drought occurrence and severity aggravating? A study on SPI drought class transitions using log-linear models and ANOVA-like inference

2012 ◽  
Vol 16 (8) ◽  
pp. 3011-3028 ◽  
Author(s):  
E. E. Moreira ◽  
J. T. Mexia ◽  
L. S. Pereira
Keyword(s):  
Time Series ◽  
Linear Models ◽  
Standardized Precipitation Index ◽  
Drought Severity ◽  
Drought Frequency ◽  
Long Duration ◽  
Long Time ◽  
Log Linear ◽  
Drought Occurrence ◽  
Drought Classes

Abstract. Long time series (95 to 135 yr) of the 12-month time scale Standardized Precipitation Index (SPI) relative to 10 locations across Portugal were studied with the aim of investigating if drought frequency and severity are changing through time. Considering four drought severity classes, time series of drought class transitions were computed and later divided into several sub-periods according to the length of SPI time series. Drought class transitions were calculated to form a 2-dimensional contingency table for each sub-period, which refer to the number of transitions among drought severity classes. Two-dimensional log-linear models were fitted to these contingency tables and an ANOVA-like inference was then performed in order to investigate differences relative to drought class transitions among those sub-periods, which were considered as treatments of only one factor. The application of ANOVA-like inference to these data allowed to compare the sub-periods in terms of probabilities of transition between drought classes, which were used to detect a possible trend in droughts frequency and severity. Results for a number of locations show some similarity between alternate sub-periods and differences between consecutive ones regarding the persistency of severe/extreme and sometimes moderate droughts. In global terms, results do not support the assumption of a trend for progressive aggravation of drought occurrence during the last century, but rather suggest the existence of long duration cycles.

The early life-history dynamics of Northeast Arctic cod: levels of natural mortality and abundance during the first 3 years of life

2016 ◽  
Vol 73 (2) ◽  
pp. 246-256 ◽  
Author(s):  
Bjarte Bogstad ◽  
Natalia A. Yaragina ◽  
Richard D.M. Nash
Keyword(s):  
Life History ◽  
Early Life ◽  
Egg Production ◽  
Gadus Morhua ◽  
Early Life History ◽  
Natural Mortality ◽  
Arctic Cod ◽  
Stock Assessments ◽  
Class Strength ◽  
New Generation

Recruitment at age 3 of the Northeast Arctic cod (Gadus morhua) is highly variable. It has generally been believed that year-class strength for this stock is determined prior to settlement to the bottom after about 6 months. However, newer observations indicate that year-class strength may change considerably between settlement and recruitment at age 3. Our analyses cover the 1983–2009 year classes where comprehensive data from total egg production (TEP), surveys, and stock assessments were available for a thorough examination of these cohorts. On average, only 6 out of 1 million of a new generation at the TEP stage reaches the age of recruitment to the fishery. The between-cohort variability in abundance is greatest at the ages 0–1 stage. Although the mortality is highest during the first months of life, the year-class strength can also be affected considerably by processes taking place between the 0-group stage (∼6 months) and age 3. The mortality in this period of life seems to be strongly density-dependent, and cannibalism is an important source of mortality.

scholarly journals Daily egg production of anchovy in European waters

2004 ◽  
Vol 61 (6) ◽  
pp. 944-958 ◽  
Author(s):  
Stylianos Somarakis ◽  
Isabel Palomera ◽  
Alberto Garcia ◽  
Luis Quintanilla ◽  
Constantin Koutsikopoulos ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Egg Production ◽  
Stock Assessment ◽  
Production Method ◽  
Bay Of Biscay ◽  
Spawning Habitat ◽  
Independent Information ◽  
Stock Biomass ◽  
Spawning Stock ◽  
The Mediterranean

Abstract Since the late 1980s, the Daily Egg Production Method (DEPM) has been applied to several anchovy stocks in European waters. DEPM surveys in the Bay of Biscay were well standardized and focused on providing fisheries-independent information for stock assessment purposes. Those targeting Mediterranean stocks were largely experimental and often opportunistic, with the main aim of developing and testing the method, rather than providing estimates of spawning stock biomass (SSB) for stock assessment. Consequently, the DEPM has been applied once, twice, or a maximum of three times in certain Mediterranean areas with no among-area standardization. Different techniques for several aspects of the method have been used in the Mediterranean, and the parameters estimated vary greatly among stocks and year of application. Evidence is provided that variability in biological production among sub-basins and/or years, a characteristic of Mediterranean Sea, may directly affect anchovy egg production. The daily specific fecundity of anchovy stocks can vary greatly among years, areas, or seasons in response to changing environmental and trophic regimes. When the correlation between regression-derived estimates of daily egg production and associated estimates of daily specific fecundity for anchovy in the Mediterranean, the Bay of Biscay, and upwelling areas are compared, a significant isometric relationship emerges for the Mediterranean and the Bay of Biscay, implying density-dependent use of spawning habitat. In upwelling areas, estimates of daily egg production are relatively high for a narrow range of generally low daily specific fecundities. There is a strong linear relationship between anchovy SSB and spawning area in European waters that does not differ significantly between the Bay of Biscay and the Mediterranean Sea.

Estimating Nonhierarchical and Nested Log-Linear Models

1981 ◽  
Vol 10 (1) ◽  
pp. 3-49 ◽  
Author(s):  
Jay Magidson ◽  
James H. Swan ◽  
Richard A. Berk
Keyword(s):  
Linear Models ◽  
Recent Literature ◽  
Computer Programs ◽  
Iterative Proportional Fitting ◽  
Nested Models ◽  
Indicator Variables ◽  
Interaction Variables ◽  
Dichotomous Variables ◽  
Using Data ◽  
Log Linear

The recent literature on-log-linear models incorrectly implies that the Iterative Proportional Fitting (IPF) algorithm and associated computer programs such as ECTA can only be used to estimate hierarchical (not nonhierarchical) log-linear models. While ECTA and similar programs are designed for the estimation of hierarchical models, it is shown here that the IPF algorithm (and existing computer programs such as ECTA) can be used to estimate any nonhierarchical model and also many nested log-linear models. The former result follows directly from the symmetry between qualitative/categorical indicator variables and appropriately defined “interaction variables.” The general approach for dichotomous variables is illustrated here using data from the study of “The American Soldier” by Stouffer et al. We also illustrate how the ECTA program can be used to estimate nested models, and show the equivalence between a particular class of nested models and the model of quasi-independence.

scholarly journals Efficacy of selective devices in reducing discards in the Nephrops trawl fishery in the Bay of Biscay

2015 ◽  
Vol 72 (6) ◽  
pp. 1869-1881 ◽  
Author(s):  
Natacha Nikolic ◽  
Joël Diméet ◽  
Spyros Fifas ◽  
Michèle Salaün ◽  
David Ravard ◽  
...  
Keyword(s):  
Generalized Linear Models ◽  
Linear Models ◽  
Mesh Size ◽  
The Other ◽  
Bay Of Biscay ◽  
Commercial Fishery ◽  
Trawl Fishery ◽  
Using Data ◽  
Flexible Grid

Abstract The Nephrops fishery in the Bay of Biscay is an important commercial fishery which generates large amounts of discards owing to the use of small mesh trawls. To reduce discards, French trawlers were equipped with a variety of selective devices, from 2005 onwards. This study examines their efficacy using data from the French on-board observer programme, 2003–2010. Generalized linear models were built for catches, discards, and landings of Nephrops and hake, controlling for the other factors which drive the variability in these variables. A dorsal square-mesh panel meant to let small hake escape did not affect hake catch, but was found to decrease Nephrops catches and discards. Among the devices intended to reduce Nephrops discards, the flexible grid was the most efficient, as it decreased catches and discards in large proportions while increasing landings but this result was supported by a small number of observations; a larger mesh size in the codend (80 mm instead of 70) slightly decreased Nephrops discards; and a ventral square-mesh panel was not found to affect catch or discards of either species. The design of the on-board observer programme was meant to estimate discard amounts, which limited their utilization to investigate factors for discarding.

scholarly journals Perceptions of Closeness in Adult Parent–Child Dyads: Asymmetry in the Context of Family Complexity

2020 ◽  
Vol 75 (10) ◽  
pp. 2219-2229
Author(s):  
Kirsten van Houdt ◽  
Matthijs Kalmijn ◽  
Katya Ivanova
Keyword(s):  
Linear Models ◽  
Biological Father ◽  
Parent Child Relations ◽  
Biological Mother ◽  
Parents And Children ◽  
Family Complexity ◽  
Married Mothers ◽  
Using Data ◽  
Log Linear ◽  
Parent Child

Abstract Objectives Multi-actor data show that parents’ and adult children’s evaluations of their relation do not necessarily match. We studied disagreement in parent- and child-reported closeness, comparing parent–child dyads involving separated parents, non-separated parents, and stepparents to shed new light on today’s diverse landscape of adult parent–child relations. Method Using data from the Parents and Children in the Netherlands (OKiN) survey, we analyzed closeness in parent–child dyads (N = 4,602) comparing (step)parents’ and their adult children’s (aged 25–45) reports. To distinguish directional disagreement (i.e., differences in child- and parent-reported means) from nondirectional disagreement (i.e., the association between child- and parent-reported measures), while accounting for absolute levels of closeness, we estimated log-linear models. Results All types of parents tend to report higher levels of closeness than their children. Whereas parental overreport is more prevalent among biological father–child dyads than among biological mother–child dyads, we found no differences between biological dyads and stepdyads. The association between children’s and parents’ reports is higher among dyads involving stepmothers or married mothers than among those involving separated mothers and (step)fathers. Discussion The intergenerational stake (i.e., parental overreport) is not unique to biological parent–child relations. Instead, patterns of disagreement seem most strongly stratified by gender.

The daily egg production method: A valid tool for application to European hake in the Bay of Biscay?

2010 ◽  
Vol 104 (1-3) ◽  
pp. 100-110 ◽  
Author(s):  
H. Murua ◽  
L. Ibaibarriaga ◽  
P. Álvarez ◽  
M. Santos ◽  
M. Korta ◽  
...  
Keyword(s):  
Egg Production ◽  
Production Method ◽  
Bay Of Biscay ◽  
European Hake

Technology, Ideology, and Societal Development

1996 ◽  
Vol 39 (1) ◽  
pp. 23-38 ◽  
Author(s):  
Patrick Nolan ◽  
Gerhard Lenski
Keyword(s):  
Religious Beliefs ◽  
Linear Models ◽  
Premarital Sex ◽  
Community Size ◽  
Political Complexity ◽  
Societal Development ◽  
Using Data ◽  
Log Linear

To address the question of whether ideology or technology has been the more powerful force shaping societies and their development, log-linear models are used to assess the association of typologies based on religious beliefs and on subsistence technology with indicators of: (1) community size, (2) political complexity, (3) stratification, (4) marital patterns, and (5) premarital sex norms. Using data derived from Murdock's Ethnographic Atlas, the analysis suggests that, although ideology is significantly associated with a number of important societal variables, the effects of technology are generally more powerful, more widespread, and more robust.

Sign in / Sign up

Export Citation Format

Share Document