A hierarchical approach to determining reference points for Pandalid shrimp

2004 ◽  
Vol 61 (8) ◽  
pp. 1373-1391 ◽  
Author(s):  
Steven X Cadrin ◽  
James A Boutillier ◽  
Josef S Idoine
Keyword(s):  
Life Histories ◽  
Reference Points ◽  
Hierarchical Approach ◽  
Precautionary Approach ◽  
Research Programs ◽  
Production Models ◽  
Biomass Dynamics ◽  
Using Data ◽  
Dynamics Models ◽  
Data Requirements

Reference points for harvesting Pandalid shrimp are categorized into five general approaches: historical proxies, biomass dynamics models, dynamic pool models, stock–recruit models, and demographic production models. Each of these approaches has different data requirements and underlying assumptions. Estimation of biological reference points from these methods can be viewed as a hierarchy, using data-poor proxies in the lowest tier to applying more informative demographic production models in the highest. Based on a review of Pandalid life histories, precautionary-approach reference points, and methodologies for estimating reference points and their applications to Pandalid shrimp stocks, we advocate a progression from proxies to more informative models and the requisite advancement of research programs to develop reliable reference points for Pandalid shrimp stocks.

Semidiscrete biomass dynamic modeling: an improved approach for assessing fish stock responses to pulsed harvest events

2012 ◽  
Vol 69 (10) ◽  
pp. 1710-1721 ◽  
Author(s):  
Michael E. Colvin ◽  
Clay L. Pierce ◽  
Timothy W. Stewart
Keyword(s):  
Time Series Data ◽  
Reference Points ◽  
Series Data ◽  
Fish Stock ◽  
Parameter Estimates ◽  
Maximum Sustained Yield ◽  
Biomass Dynamic ◽  
Biomass Dynamics ◽  
Discrete Manner ◽  
Dynamics Models

Continuous harvest over an annual period is a common assumption of continuous biomass dynamics models (CBDMs); however, fish are frequently harvested in a discrete manner. We developed semidiscrete biomass dynamics models (SDBDMs) that allow discrete harvest events and evaluated differences between CBDMs and SDBDMs using an equilibrium yield analysis with varying levels of fishing mortality (F). Equilibrium fishery yields for CBDMs and SDBDMS were similar at low fishing mortalities and diverged as F approached and exceeded maximum sustained yield (FMSY). Discrete harvest resulted in lower equilibrium yields at high levels of F relative to continuous harvest. The effect of applying harvest continuously when it was in fact discrete was evaluated by fitting CBDMs and SDBDMs to time series data generated from a hypothetical fish stock undergoing discrete harvest and evaluating parameter estimates bias. Violating the assumption of continuous harvest resulted in biased parameter estimates for CBDM while SDBDM parameter estimates were unbiased. Biased parameter estimates resulted in biased biological reference points derived from CBDMs. Semidiscrete BDMs outperformed continuous BDMs and should be used when harvest is discrete, when the time and magnitude of harvest are known, and when F is greater than FMSY.

Migration and the Internet

2017 ◽  
Vol 14 (3) ◽  
pp. 331-342 ◽  
Author(s):  
Thomas John Cooke ◽  
Ian Shuttleworth
Keyword(s):  
United States ◽  
Information And Communication Technologies ◽  
Unobserved Heterogeneity ◽  
Panel Study ◽  
The United States ◽  
Negative Effect ◽  
Information And Communication ◽  
Using Data ◽  
And Migration ◽  
Dynamics Models

It is widely presumed that information and communication technologies, or ICTs, enable migration in several ways; primarily by reducing the costs of migration. However, a reconsideration of the relationship between ICTs and migration suggests that ICTs may just as well hinder migration; primarily by reducing the costs of not moving.  Using data from the US Panel Study of Income Dynamics, models that control for sources of observed and unobserved heterogeneity indicate a strong negative effect of ICT use on inter-state migration within the United States. These results help to explain the long-term decline in internal migration within the United States.

scholarly journals Is Continuous Eruption Related to Periodontal Changes? A 16-Year Follow-up

2021 ◽  
pp. 002203452199936
Author(s):  
C. Wiedemann ◽  
C. Pink ◽  
A. Daboul ◽  
S. Samietz ◽  
H. Völzke ◽  
...  
Keyword(s):  
Tooth Wear ◽  
Total Sample ◽  
Population Based ◽  
Tooth Eruption ◽  
Reference Points ◽  
3 Dimensional ◽  
Probing Depth ◽  
Molar Teeth ◽  
Using Data

The aims of this study were to 1) determine if continuous eruption occurs in the maxillary teeth, 2) assess the magnitude of the continuous eruption, and 3) evaluate the effects of continuous eruption on the different periodontal parameters by using data from the population-based cohort of the Study of Health in Pomerania (SHIP). The jaw casts of 140 participants from the baseline (SHIP-0) and 16-y follow-up (SHIP-3) were digitized as 3-dimensional models. Robust reference points were set to match the tooth eruption stage at SHIP-0 and SHIP-3. Reference points were set on the occlusal surface of the contralateral premolar and molar teeth, the palatal fossa of an incisor, and the rugae of the hard palate. Reference points were combined to represent 3 virtual occlusal planes. Continuous eruption was measured as the mean height difference between the 3 planes and rugae fix points at SHIP-0 and SHIP-3. Probing depth, clinical attachment levels, gingiva above the cementoenamel junction (gingival height), and number of missing teeth were clinically assessed in the maxilla. Changes in periodontal variables were regressed onto changes in continuous eruption after adjustment for age, sex, number of filled teeth, and education or tooth wear. Continuous tooth eruption >1 mm over the 16 y was found in 4 of 140 adults and averaged to 0.33 mm, equaling 0.021 mm/y. In the total sample, an increase in continuous eruption was significantly associated with decreases in mean gingival height ( B = −0.34; 95% CI, −0.65 to −0.03). In a subsample of participants without tooth loss, continuous eruption was negatively associated with PD. This study confirmed that continuous eruption is clearly detectable and may contribute to lower gingival heights in the maxilla.

Reference points for the length-based indicator Lmax5% for use in the assessment of data-limited stocks

2019 ◽  
Vol 76 (7) ◽  
pp. 2125-2139 ◽  
Author(s):  
Tanja Miethe ◽  
Yves Reecht ◽  
Helen Dobby
Keyword(s):  
Life Histories ◽  
Stock Assessment ◽  
Reference Points ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Simulation Tools ◽  
Spawning Potential Ratio ◽  
The Mean ◽  
Commercial Sources ◽  
Length Frequency Data

Abstract In the absence of abundance indices from scientific surveys or commercial sources, reliable length frequency data from sampled commercial catches can be used to provide an indirect assessment of fishing mortality. Length-based indicators are simple metrics which describe length frequency distributions. The length-based indicator Lmax5%, the mean length of the largest 5% of individuals in the catch, combined with appropriately selected reference points, can be used to evaluate the presence of very large individuals in the catch and hence determine exploitation level. Using analytical per-recruit models, we derive reference points consistent with a spawning potential ratio of 40%. The reference points depend on the life history parameters for natural mortality, maturity, and growth (M, Lmat, L∞, k, CVL∞). Using available simulation tools, we investigate the sensitivity of the reference points to errors in these parameters and explore the usefulness of particular reference points for management purposes for stocks with different life histories. The proposed reference points are robust to uncertainty in length at first capture, Lc, and take into account the maturation schedule of a species. For those stocks with high M/k ratios (>1), Lmax5%, combined with the appropriate reference point, can be used to provide a data-limited stock assessment.

scholarly journals Reference points and management strategies: lessons from quantum mechanics

2006 ◽  
Vol 63 (1) ◽  
pp. 4-11 ◽  
Author(s):  
Jon T. Schnute ◽  
Rowan Haigh
Keyword(s):  
Quantum Mechanics ◽  
Management Strategies ◽  
Practical Importance ◽  
Reference Points ◽  
Surplus Production ◽  
Management Algorithm ◽  
Production Models ◽  
Conceptual Role ◽  
Common Framework ◽  
Mathematical Algorithms

Abstract Fisheries management often relies heavily on precautionary reference points estimated from complex statistical models. An alternative approach uses management strategies defined by mathematical algorithms that calculate controls, like catch quotas, directly from the observed data. We combine these two distinct paradigms into a common framework using arguments from the historical development of quantum mechanics. In fisheries, as in physics, the core of the argument lies in the technical details. We illustrate the process of designing a management algorithm similar to one actually used by the International Whaling Commission. Reference points and surplus production models play a conceptual role in defining management strategies, even if marine populations do not obey such simplistic rules. Physicists have encountered similar problems in formulating quantum theory, where mathematical objects with seemingly unrealistic properties generate results of great practical importance.

scholarly journals Fisheries Reference Point and Stock Status of Croaker Fishery (Sciaenidae) Exploited from the Bay of Bengal, Bangladesh

2022 ◽  
Vol 10 (1) ◽  
pp. 63
Author(s):  
Partho Protim Barman ◽  
Md. Mostafa Shamsuzzaman ◽  
Petra Schneider ◽  
Mohammad Mojibul Hoque Mozumder ◽  
Qun Liu
Keyword(s):  
Bay Of Bengal ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Production Model ◽  
Fishing Pressure ◽  
Surplus Production ◽  
Stock Status ◽  
Management Measures ◽  
Production Models ◽  
The Monte Carlo Method

This research evaluated fisheries reference points and stock status to assess the sustainability of the croaker fishery (Sciaenidae) from the Bay of Bengal (BoB), Bangladesh. Sixteen years (2001–2016) of catch-effort data were analyzed using two surplus production models (Schaefer and Fox), the Monte Carlo method (CMSY) and the Bayesian state-space Schaefer surplus production model (BSM) method. This research applies a Stock–Production Model Incorporating Covariates (ASPIC) software package to run the Schaefer and Fox model. The maximum sustainable yield (MSY) produced by all models ranged from 33,900 to 35,900 metric tons (mt), which is very close to last year’s catch (33,768 mt in 2016). The estimated B > BMSY and F < FMSY indicated the safe biomass and fishing status. The calculated F/FMSY was 0.89, 0.87, and 0.81, and B/BMSY was 1.05, 1.07, and 1.14 for Fox, Schaefer, and BSM, respectively, indicating the fully exploited status of croaker stock in the BoB, Bangladesh. The representation of the Kobe phase plot suggested that the exploitation of croaker stock started from the yellow (unsustainable) quadrant in 2001 and gradually moved to the green (sustainable) quadrant in 2016 because of the reduction in fishing efforts and safe fishing pressure after 2012. Thus, this research suggests that the current fishing pressure needs to be maintained so that the yearly catch does not exceed the MSY limit of croaker. Additionally, specific management measures should implement to guarantee croaker and other fisheries from the BoB.

scholarly journals Data-limited management reference points to avoid collapse of stocks dependent on learned migration behaviour

2012 ◽  
Vol 69 (2) ◽  
pp. 267-270 ◽  
Author(s):  
Alec D. MacCall
Keyword(s):  
Reference Points ◽  
Marine Science ◽  
Precautionary Approach ◽  
Structured Population ◽  
Migration Behaviour ◽  
Spawning Potential Ratio ◽  
Age Structured ◽  
Age Structured Population ◽  
Stock Collapse

AbstractMacCall, A. D. 2012. Data-limited management reference points to avoid collapse of stocks dependent on learned migration behaviour. – ICES Journal of Marine Science, 69: 267–270. Risk of stock collapse associated with the loss of a stock's migrational knowledge may be underestimated by conventional reference points. In this paper, I describe three different approaches: a data-poor precautionary approach is to ensure that individuals spawn at least twice; a data-intermediate approach is to calculate a repeat spawning potential ratio (rSPR), which is analogous to the conventional SPR; and for data-rich cases, age-structured population simulations are recommended.

Efficiency of Indigenous and Intercultural Higher Education and Research Programs

2021 ◽  
Vol 2 (2) ◽  
pp. 29-44
Author(s):  
José G. Vargas-Hernández ◽  
Ernesto Guerra-García
Keyword(s):  
Higher Education ◽  
Data Envelopment Analysis ◽  
Educational Programs ◽  
Intermediate Level ◽  
The Other ◽  
Total Efficiency ◽  
Data Envelopment ◽  
Research Programs ◽  
Government Financing ◽  
Using Data

A study was carried out using data envelopment analysis, in which variables (inputs and outputs) of a group of 13 public HEIs from the northwest of the country were compared with data from the 2018-2019 cycle to characterize the UAIM. It was found that 1) when considering government financing and generated own resources, UAIM has an efficiency of 39%; 2) when considering ordinary financing and tuition, the institution is 100% efficient; 3) in relation to the total number of teachers and enrollment has an efficiency of 39%, it has the capacity to serve up to 14,325 students; 4) it has an efficiency of 26% in relation to the total and accredited educational programs; and 5) the total efficiency is 51% and represents an intermediate level with respect to the other HEIs, which on average is 56%.

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