Nonstationarity of Production Relationships in Exploited Populations

1987 ◽  
Vol 44 (S2) ◽  
pp. s156-s165 ◽  
Author(s):  
Carl J. Walters

Stock assessment usually proceeds from the assumption that there are time-invariant relationships between stock size and rate processes such as recruitment, although such relationships are difficult to discern due to noise caused by factors other than stock size. There are good biological reasons not to trust this assumption in exploited populations, where persistent environmental changes and shifts in stock structure may cause various parameters to change. Graphical and statistical procedures can be used to detect this nonstationarity in historical data sets for which stock size has varied so as to repeatedly sample a range of sizes. The policy implications of nonstationarity depend on whether the changes are clearly observable as deviations from known, Song-term baseline responses. If the changes are observable, it is usually best to pretend that the current deviation will persist unless strong constraints on policy change make it necessary to plan for changes that may occur far into the future. If the changes are not observable (the usual case), then it is necessary to make a difficult policy choice between passively waiting for informative stock responses versus actively experimenting with harvest rates so as to quickly get information about responses over a range of stock sizes.

2021 ◽  
Vol 7 (s2) ◽  
Author(s):  
Alexander Bergs

Abstract This paper focuses on the micro-analysis of historical data, which allows us to investigate language use across the lifetime of individual speakers. Certain concepts, such as social network analysis or communities of practice, put individual speakers and their social embeddedness and dynamicity at the center of attention. This means that intra-speaker variation can be described and analyzed in quite some detail in certain historical data sets. The paper presents some exemplary empirical analyses of the diachronic linguistic behavior of individual speakers/writers in fifteenth to seventeenth century England. It discusses the social factors that influence this behavior, with an emphasis on the methodological and theoretical challenges and opportunities when investigating intra-speaker variation and change.


Author(s):  
Takeshi Mizunoya ◽  
Noriko Nozaki ◽  
Rajeev Kumar Singh

AbstractIn the early 2000s, Japan instituted the Great Heisei Consolidation, a national strategy to promote large-scale municipal mergers. This study analyzes the impact that this strategy could have on watershed management. We select the Lake Kasumigaura Basin, the second largest lake in Japan, for the case study and construct a dynamic expanded input–output model to simulate the ecological system around the Lake, the socio-environmental changes over the period, and their mutual dependency for the period 2012–2020. In the model, we regulate and control the following water pollutants: total nitrogen, total phosphorus, and chemical oxygen demand. The results show that a trade-off between economic activity and the environment can be avoided within a specific range of pollution reduction, given that the prefectural government implements optimal water environment policies, assuming that other factors constraining economic growth exist. Additionally, municipal mergers are found to significantly reduce the budget required to improve the water environment, but merger budget efficiency varies nonlinearly with the reduction rate. Furthermore, despite the increase in financial efficiency from the merger, the efficiency of installing domestic wastewater treatment systems decreases drastically beyond a certain pollution reduction level and eventually reaches a limit. Further reductions require direct regulatory instruments in addition to economic policies, along with limiting the output of each industry. Most studies on municipal mergers apply a political, administrative, or financial perspective; few evaluate the quantitative impact of municipal mergers on the environment and environmental policy implications. This study addresses these gaps.


Author(s):  
Ebony I Weems ◽  
Noé U de la Sancha ◽  
Laurel J Anderson ◽  
Carlos Zambrana-Torrelio ◽  
Ronaldo P Ferraris

Synopsis We argue that the current environmental changes stressing the Earth’s biological systems urgently require study from an integrated perspective to reveal unexpected, cross-scale interactions, particularly between microbes and macroscale phenomena. Such interactions are the basis of a mechanistic understanding of the important connections between deforestation and emerging infectious disease, feedback between ecosystem disturbance and the gut microbiome, and the cross-scale effects of environmental pollutants. These kinds of questions can be answered with existing techniques and data, but a concerted effort is necessary to better coordinate studies and data sets from different disciplines to fully leverage their potential.


1997 ◽  
Vol 102 (C13) ◽  
pp. 27835-27860 ◽  
Author(s):  
Alexey Kaplan ◽  
Yochanan Kushnir ◽  
Mark A. Cane ◽  
M. Benno Blumenthal

2017 ◽  
Vol 21 (2) ◽  
pp. 317-340 ◽  
Author(s):  
HENDRIK DE SMET ◽  
FREEK VAN DE VELDE

While it is undoubtedly true that historical data do not lend themselves well to the reproduction of experimental findings, the availability of increasingly extensive data sets has brought some experimenting within practical reach. This means that certain predictions based on a combination of synchronic observations and uniformitarian thinking are now testable. Synchronic evidence shows a negative correlation between analysability in morphologically complex words and various measures of frequency. It is therefore expected that when the frequency of morphologically complex items changes, their analysability will change along with this. If analysability decreases, this should in turn be reflected in decreasing sensitivity to priming by items with analogous composition. The latter prediction is in principle testable on diachronic data, offering a way of verifying the diachronic effect of frequency change on analysability. In this spirit, the present article examines the relation between changing frequency and priming sensitivity, as a proxy to analysability. This is done for a sample of 250 English ly-adverbs, such as roughly, blindly, publicly, etc. over the period 1950–2005, using data from the Hansard Corpus. Some of the expected relations between frequency and analysability can be shown to hold, albeit with great variation across lexical items. At the same time, much of the variation in our measure of analysability cannot be accounted for by frequency or frequency change alone.


2021 ◽  
pp. 133-140
Author(s):  
C. Hardner ◽  
K. Gasic ◽  
C. da Silva Linge ◽  
M. Worthington ◽  
D. Byrne ◽  
...  

Proceedings ◽  
2019 ◽  
Vol 44 (1) ◽  
pp. 8
Author(s):  
Ivan J. Ramírez ◽  
Jieun Lee

El Niño is a climatic cycle originating in the tropical Pacific Ocean that impacts countries in Latin America. It is often associated with water-based infectious diseases, many of which are also poverty-related. In this study we explore ecosyndemic risk and social vulnerability in Guatemala during the 2014–2016 El Niño. An ecosyndemic is a cluster of diseases, associated with environmental changes, set within a wider context of socioeconomic inequities. Using GIS, we examined six infectious diseases and ecosyndemic risk in Guatemala from 2014 to 2016 and factors of social risk at the department level. Preliminary results and policy implications are discussed.


Hypatia ◽  
2014 ◽  
Vol 29 (3) ◽  
pp. 599-616 ◽  
Author(s):  
Kyle Powys Whyte

Indigenous peoples must adapt to current and coming climate‐induced environmental changes like sea‐level rise, glacier retreat, and shifts in the ranges of important species. For some indigenous peoples, such changes can disrupt the continuance of the systems of responsibilities that their communities rely on self‐consciously for living lives closely connected to the earth. Within this domain of indigeneity, some indigenous women take seriously the responsibilities that they may perceive they have as members of their communities. For the indigenous women who have such outlooks, responsibilities that they assume in their communities expose them to harms stemming from climate change impacts and other environmental changes. Yet at the same time, their commitment to these responsibilities motivates them to take on leadership positions in efforts at climate change adaptation and mitigation. I show why, at least for some indigenous women, this is an important way of framing the climate change impacts that affect them. I then argue that there is an important implication in this conversation for how we understand the political responsibilities of nonindigenous parties for supporting distinctly indigenous efforts at climate change adaptation and mitigation.


2019 ◽  
Vol 76 (7) ◽  
pp. 2020-2032 ◽  
Author(s):  
Chang Liu ◽  
Crista Bank ◽  
Michael Kersula ◽  
Geoffrey W Cowles ◽  
Douglas R Zemeckis ◽  
...  

Abstract Atlantic halibut are a “Species of Concern” in US waters and little is known about their movements and stock structure. Recent stock assessments drew attention to the paucity of information for assessing and managing this stock. To investigate movement patterns and stock structure, halibut were tagged off Massachusetts and Maine within US waters of the Gulf of Maine region using pop-up satellite archival tags and data storage tags. A hidden Markov model (HMM) geolocation method previously developed for other groundfish species was adapted to estimate the movement tracks of the tagged halibut (n = 25) based on the tag-recorded depth and temperature. Total distance travelled based on geolocation ranged from 36 to 1701 km, whereas straight line distance between tagging and end locations ranged from 0.4 to 440.7 km. Estimated movement rates varied between 2.7 and 10 km day−1. Two tagged halibut made long-distance movements to putative spawning habitat in the Northeast Channel off Georges Bank. Thirteen (13) out of 25 geolocated individuals were estimated to have reached Canadian waters. Geolocation results revealed home range, return movement, and seasonal migration movement patterns exhibited by the tagged halibut. The HMM geolocation method could be a useful tool in providing information on halibut movements that can inform stock assessment and management decisions.


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