A Stochastic Population Model for Managing the Atlantic Menhaden (Brevoortia tyrannus) Fishery and Assessing Managerial Risks

1985 ◽  
Vol 42 (8) ◽  
pp. 1371-1379 ◽  
Author(s):  
D. Ruppert ◽  
R. L Reish ◽  
R. B. Deriso ◽  
R. J. Carroll
Keyword(s):  
Population Model ◽  
Atlantic Menhaden ◽  
Juvenile Growth ◽  
Fishing Mortality ◽  
Brevoortia Tyrannus ◽  
Estimation Errors ◽  
Age Dependent ◽  
Stochastic Recruitment ◽  
Stochastic Population Model

A model including an age-structure, a stochastic egg-recruitment relationship, density-dependent juvenile growth, age-dependent fishing mortality, and fecundity dependent upon size as well as age was used to investigate three types of harvesting strategies: constant yearly catch policies, constant fishing mortality rate policies, and "egg escapement" policies, which are defined in the article. Because of stochastic recruitment, constant yearly catch policies appear unsuitable for managing Atlantic menhaden (Brevoortia tyrannus). Both other types of policies are suitable, but the egg escapement policies have higher long-term average catches. Using decision theory, we investigated risks due to the randomness of recruitment and to the estimation errors for the biographical parameters in our model. The risks appear to be acceptable.

An Investigation of the Population Dynamics of Atlantic Menhaden (Brevoortia tyrannus)

1985 ◽  
Vol 42 (S1) ◽  
pp. s147-s157 ◽  
Author(s):  
R. L Reish ◽  
R. B. Deriso ◽  
D. Ruppert ◽  
R. J. Carroll
Keyword(s):  
Population Dynamics ◽  
Environmental Variables ◽  
Atlantic Menhaden ◽  
Ekman Transport ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Brevoortia Tyrannus ◽  
Ricker Model ◽  
Dependent Growth ◽  
Special Case

The following biological components concerning the population dynamics of Atlantic menhaden (Brevoortia tyrannus) were investigated: growth, natural mortality, migration, fishing mortality, and recruitment. We found that a hypothesis of density-dependent growth is strongly supported by the data and that the dependence of growth on abundance appears to occur prior to recruitment. Age-specific natural mortality estimates seem biologically reasonable, except the estimate for age 1 menhaden, which appears to be too low. Most of the estimated migration probabilities also seem to be biologically reasonable, especially during the summer season for age 2 fish. Estimated age-specific fishing mortality rates demonstrate the increased fishing pressure on age 3 and younger fish since the early 1960's. When the environmental variables (temperature and Ekman transport) are excluded from the spawner–recruit analysis, then the Beverton–Holt model fits as well as other models examined, and it is the only model that is significant at the 0.05 probability level. Of the environmental variables examined, only westward Ekman transport in the South Atlantic region shows a relationship with recruitment. The unnormalized gamma function, which includes the Ricker model as a special case, is more responsive to the inclusion of westward Ekman transport than the Beverton–Holt model.

COVID - 19 AND THE PROBLEM OF PERSONALITY

2020 ◽  
pp. 31-35
Author(s):  
Mazaeva N.A. ◽  
Golovina A.G.
Keyword(s):  
General Population ◽  
Age Groups ◽  
Personal Transformation ◽  
Personality Changes ◽  
Age Dependent

In order to determine possible trends in the dynamics and characterological structure of personality in the General population caused by the COVID-19 pandemic, which is a long-term strong stressful effect and clinically and psychopathologically comparable to chronic personality changes after experiencing a disaster, the conditions predisposing to personal transformation, including clinical and prognostic patterns, are analyzed. The age-dependent nature of these changes is shown, and a number of features identified for different age groups are discussed.

Effect of long-term treatment with L-deprenyl on the age-dependent microanatomical changes in the rat hippocampus

1995 ◽  
Vol 79 (2-3) ◽  
pp. 169-185 ◽  
Author(s):  
Yong-Chun Zeng ◽  
Stefano Bongrani ◽  
Elena Bronzetti ◽  
Sandro Cadel ◽  
Alberto Ricci ◽  
...  
Keyword(s):  
Term Treatment ◽  
Rat Hippocampus ◽  
Long Term Treatment ◽  
Age Dependent

Seizure induced synthesis of fibronectin is rapid and age dependent: implications for long-term potentiation and sprouting

1998 ◽  
Vol 812 (1-2) ◽  
pp. 209-215 ◽  
Author(s):  
Keith B Hoffman ◽  
Jason K Pinkstaff ◽  
Christine M Gall ◽  
Gary Lynch
Keyword(s):  
Long Term Potentiation ◽  
Term Potentiation ◽  
Age Dependent

An Alternative Perspective on Recruitment Overfishing and Biological Reference Points

1987 ◽  
Vol 44 (4) ◽  
pp. 913-918 ◽  
Author(s):  
M. P. Sissenwine ◽  
J. G. Shepherd
Keyword(s):  
Fisheries Management ◽  
Reference Point ◽  
Reference Points ◽  
Fishing Mortality ◽  
Alternative Perspective ◽  
Conventional Models ◽  
Definition Of ◽  
Yield Per Recruit ◽  
Spawning Biomass

Biological reference points are used to guide fisheries management decisions. The reference points most often used are expressed in terms of fishing mortality rate (F). Fmsy relates to the maximization of sustainable yield. In principle, it is a most useful reference point, but in practice it is difficult to estimate. Fmax and F0.1 relate to certain levels of yield per recruit and are easily estimated, but they ignore conservation of the resource. Recruitment overfishing has usually been understood to occur when a population has been fished down to a point where recruitment is substantially reduced or fails. It has not been used as a basis for a biological reference point because the definition is vague and cannot be readily related to fishing mortality. Levels of spawning biomass below which recruitment seems to be reduced have been used, but their determination from available data is usually difficult and controversial. We propose an alternative definition of recruitment overfishing in terms of the level of fishing pressure that reduces the spawning biomass of a year class over its lifetime below the spawning biomass of its parents on average. Conventional models and types of data can be used to determine this level of F, denoted as Frep, which clearly relates to the replacement of spawning biomass and thus to sustainability of a population and yield in the long term.

scholarly journals Measuring fisheries performance using the “Goldilocks plot”

2018 ◽  
Vol 76 (1) ◽  
pp. 45-49 ◽  
Author(s):  
Ray Hilborn
Keyword(s):  
Primary Objective ◽  
Regional Level ◽  
Fishing Mortality ◽  
Policy Makers ◽  
The Public ◽  
Stock Status ◽  
Realistic Information ◽  
Rate Threshold ◽  
The Eu

Abstract Most reporting of stock status accumulated at a national or regional level gives statistics on what proportion of the stocks are below some abundance threshold or above some fishing mortality rate threshold. This approach does not convey useful information on the performance of the fisheries management system in maximizing long-term sustainable yield, which is the primary objective of most national and international fisheries legislation. In this paper, I present a graphical approach for representing how much yield is being lost as a consequence of current suboptimal abundance and fishing pressure. Using the EU stocks assessed by ICES as an example, I show how traditional criteria for overfished and overfishing fail to display realistic information about the performance of the fishery. This approach provides much more useful information for the public and policy makers.

scholarly journals A Multivariate Assessment of Age-Related Cognitive Impairment in Octodon degus

2021 ◽  
Vol 15 ◽  
Author(s):  
Daniela S. Rivera ◽  
Carolina B. Lindsay ◽  
Carolina A. Oliva ◽  
Francisco Bozinovic ◽  
Nibaldo C. Inestrosa
Keyword(s):  
Recognition Memory ◽  
Cognitive Performance ◽  
Natural Aging ◽  
Long Term Memory ◽  
Barnes Maze ◽  
Short Term ◽  
Term Memory ◽  
Age Related ◽  
Age Dependent

Aging is a progressive functional decline characterized by a gradual deterioration in physiological function and behavior. The most important age-related change in cognitive function is decline in cognitive performance (i.e., the processing or transformation of information to make decisions that includes speed of processing, working memory, and learning). The purpose of this study is to outline the changes in age-related cognitive performance (i.e., short-term recognition memory and long-term learning and memory) in long-lived Octodon degus. The strong similarity between degus and humans in social, metabolic, biochemical, and cognitive aspects makes it a unique animal model for exploring the mechanisms underlying the behavioral and cognitive deficits related to natural aging. In this study, we examined young adult female degus (12- and 24-months-old) and aged female degus (38-, 56-, and 75-months-old) that were exposed to a battery of cognitive-behavioral tests. Multivariate analyses of data from the Social Interaction test or Novel Object/Local Recognition (to measure short-term recognition memory), and the Barnes maze test (to measure long-term learning and memory) revealed a consistent pattern. Young animals formed a separate group of aged degus for both short- and long-term memories. The association between the first component of the principal component analysis (PCA) from short-term memory with the first component of the PCA from long-term memory showed a significant negative correlation. This suggests age-dependent differences in both memories, with the aged degus having higher values of long-term memory ability but poor short-term recognition memory, whereas in the young degus an opposite pattern was found. Approximately 5% of the young and 80% of the aged degus showed an impaired short-term recognition memory; whereas for long-term memory about 32% of the young degus and 57% of the aged degus showed decreased performance on the Barnes maze test. Throughout this study, we outlined age-dependent cognitive performance decline during natural aging in degus. Moreover, we also demonstrated that the use of a multivariate approach let us explore and visualize complex behavioral variables, and identified specific behavioral patterns that allowed us to make powerful conclusions that will facilitate further the study on the biology of aging. In addition, this study could help predict the onset of the aging process based on behavioral performance.

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