- Stock Assessment Through Egg Production Methods in the U.S.

2014 ◽  
pp. 321-347
Keyword(s):  
Egg Production ◽  
Stock Assessment ◽  
Production Methods ◽  
The U.S

Egg production methods in marine fisheries: An introduction

2012 ◽  
Vol 117-118 ◽  
pp. 1-5 ◽  
Author(s):  
M. Bernal ◽  
S. Somarakis ◽  
P.R. Witthames ◽  
C.J.G. van Damme ◽  
A. Uriarte ◽  
...  
Keyword(s):  
Egg Production ◽  
Marine Fisheries ◽  
Production Methods

scholarly journals A revision of daily egg production estimation methods, with application to Atlanto-Iberian sardine. 2. Spatially and environmentally explicit estimates of egg production

2011 ◽  
Vol 68 (3) ◽  
pp. 528-536 ◽  
Author(s):  
Miguel Bernal ◽  
Yorgos Stratoudakis ◽  
Simon Wood ◽  
Leire Ibaibarriaga ◽  
Luis Valdés ◽  
...  
Keyword(s):  
Temporal Variability ◽  
Environmental Variables ◽  
Egg Production ◽  
Stock Assessment ◽  
Production Model ◽  
Estimation Methods ◽  
Statistical Framework ◽  
Spatio Temporal ◽  
The Relationship ◽  
Made In

Abstract Bernal, M., Stratoudakis, Y., Wood, S., Ibaibarriaga, L., Uriarte, A., Valdés, L., and Borchers, D. 2011. A revision of daily egg production estimation methods, with application to Atlanto-Iberian sardine. 2. Spatially and environmentally explicit estimates of egg production. – ICES Journal of Marine Science, 68: . A spatially and environmentally explicit egg production model is developed to accommodate a number of assumptions about the relationship between egg production and mortality and associated environmental variables. The general model was tested under different assumptions for Atlanto-Iberian sardine. It provides a flexible estimator of egg production, in which a range of assumptions and hypotheses can be tested in a structured manner within a well-defined statistical framework. Application of the model to Atlanto-Iberian sardine increased the precision of the egg production time-series, and allowed improvements to be made in understanding the spatio-temporal variability in egg production, as well as implications for ecology and stock assessment.

Robustness of egg production methods as a fishery independent alternative to assess the Eastern Baltic cod stock (Gadus morhua callarias L.)

2012 ◽  
Vol 117-118 ◽  
pp. 75-85 ◽  
Author(s):  
Gerd Kraus ◽  
Hans-Harald Hinrichsen ◽  
Rüdiger Voss ◽  
Eske Teschner ◽  
Jonna Tomkiewicz ◽  
...  
Keyword(s):  
Egg Production ◽  
Gadus Morhua ◽  
Production Methods ◽  
Eastern Baltic ◽  
Baltic Cod

Spatiotemporal modelling for the annual egg production method of stock assessment using generalized additive models

1998 ◽  
Vol 55 (12) ◽  
pp. 2608-2621 ◽  
Author(s):  
N H Augustin ◽  
D L Borchers ◽  
E D Clarke ◽  
S T Buckland ◽  
M Walsh
Keyword(s):  
Environmental Variables ◽  
Egg Production ◽  
Survey Design ◽  
Stock Assessment ◽  
Generalized Additive Models ◽  
Production Method ◽  
Additive Models ◽  
Atlantic Mackerel ◽  
Egg Density ◽  
Survey Designs

Generalized additive models (GAMs) are used to model the spatiotemporal distribution of egg density as a function of locational and environmental variables. The main aim of using GAMs is to improve precision of egg abundance estimates needed for the annual egg production method. The application of GAMs requires a survey design with good coverage in space and time. If the only results available are from less optimal survey designs, they can be improved by using historical data for spawning boundaries. The method is applied to plankton egg survey data of Atlantic mackerel (Scomber scombrus) in 1995. The GAM-based method improves the precision of estimates substantially and is also useful in explaining complex space-time trends using environmental variables.

scholarly journals The Effects of Consideration of Future and Immediate Consequences on Willingness to Pay for Eco-Friendly Plant Attributes

2014 ◽  
Vol 32 (2) ◽  
pp. 64-70
Author(s):  
Hayk Khachatryan ◽  
Chengyan Yue ◽  
Ben Campbell ◽  
Bridget Behe ◽  
Charlie Hall
Keyword(s):  
Willingness To Pay ◽  
Ornamental Plants ◽  
Production Method ◽  
Price Premium ◽  
Production Methods ◽  
Consideration Of Future Consequences ◽  
Plant Attributes ◽  
Using Data ◽  
Future Consequences ◽  
The U.S

We investigated how differences in the consideration of future consequences (CFC) influence consumers' willingness to pay for edible and ornamental plants using data from plant auction experiments conducted in the U.S. and Canada. Specifically, the study focused on individuals' preferences for plant attributes related to production method, container type, and product origin. Individuals assigning higher importance to future consequences of their current decisions were willing to pay a price premium for plants grown using sustainable (16.7 cents) and energy-saving (16.5 cents) production methods, non-conventional containers such as compostable (18.2 cents) and plantable (14.3 cents), and locally produced plants (15.3 cents), and they expected a discount (37.8 cents) to purchase imported plants (i.e., produced outside the U.S.). In contrast, individuals assigning higher importance to immediate outcomes of their decisions were not willing to pay a price premium for the above mentioned attributes, with the exception of water-saving and compostable ones. The results contribute to our understanding of the effects of temporal considerations on choice decision making by horticultural consumers, and provide horticultural marketers with an opportunity to effectively position products that provide long- or short-term benefits.

Egg production methods applied to Eastern Baltic cod provide indices of spawning stock dynamics

2020 ◽  
Vol 227 ◽  
pp. 105553 ◽  
Author(s):  
Friedrich W. Köster ◽  
Bastian Huwer ◽  
Gerd Kraus ◽  
Rabea Diekmann ◽  
Margit Eero ◽  
...  
Keyword(s):  
Egg Production ◽  
Production Methods ◽  
Spawning Stock ◽  
Eastern Baltic ◽  
Baltic Cod

Recruitment variation in abalone: Its importance to fisheries management

1995 ◽  
Vol 46 (3) ◽  
pp. 555 ◽  
Author(s):  
PE McShane
Keyword(s):  
Egg Production ◽  
Field Experiments ◽  
Stock Assessment ◽  
Reference Points ◽  
High Fecundity ◽  
Spatial And Temporal Scales ◽  
Recruitment Failure ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Many Sources

Recruitment failure has been implicated in the decline of several abalone fisheries. Traditionally, fisheries scientists invoke theoretical stock-recruitment relationships to predict trends in abundance of an exploited stock under various harvest regimes. The empirical evidence in support of a positive relationship between spawning stock and recruits is not strong. A further problem in interpretation of such relationships is that both 'stock' and 'recruitment' have various definitions in fisheries and ecological literature. The definition of a stock for abalone is not clear. As emphasized in this review, which considers each stage in the life history of abalone, the abundance of spawners is one of many sources of variation in recruitment. The evidence for invertebrates, particularly those with high fecundity, is that recruitment varies independently of the abundance of spawners. This is also the case for abalone, where recruits have been measured as the density of immediate post-settlement individuals, juveniles, or as adults entering the exploitable stock. A problem with stock-recruitment hypotheses is that they have intuitive appeal. It is considered 'dangerous' to manage fisheries under the assumption that a reduction in the number of spawners by fishing will not affect recruitment. Such danger to abalone stocks has been more recently assessed by egg-per-recruit analyses, whereby various harvest strategies are examined relative to reference points for egg production. These studies are reviewed and assessed relative to the often conflicting aims of managers and scientists. This review of studies of recruitment variation in abalone emphasizes the need for a more rigorous, autecological approach to stock assessment in which field experiments are conducted over realistic spatial and temporal scales, permitting robust testing of hypotheses.

A reanalysis of North Sea plaice spawning-stock biomass using the annual egg production method

2009 ◽  
Vol 66 (9) ◽  
pp. 1999-2011 ◽  
Author(s):  
Cindy J. G. van Damme ◽  
Loes J. Bolle ◽  
Clive J. Fox ◽  
Petter Fossum ◽  
Gerd Kraus ◽  
...  
Keyword(s):  
North Sea ◽  
Egg Production ◽  
Stock Assessment ◽  
Population Analysis ◽  
Spatial Dynamics ◽  
Production Method ◽  
Southern Bight ◽  
The North ◽  
Stock Biomass ◽  
Spawning Stock

Abstract van Damme, C. J. G., Bolle, L. J., Fox, C. J., Fossum, P., Kraus, G., Munk, P., Rohlf, N., Witthames, P. R., and Dickey-Collas, M. 2009. A reanalysis of North Sea plaice spawning-stock biomass using the annual egg production method. – ICES Journal of Marine Science, 66: 1999–2011. Uncertainty about the quality of current virtual population analysis-based stock assessment for North Sea plaice (Pleuronectes platessa) has led to various abundance indices. We compared biomass estimates from the annual egg production (AEP) method with current stock assessments based on catch-at-age to validate the current and historical perception of exploitation. The AEP method was also used to investigate the dynamics of the spatial components of plaice in the North Sea. We corrected for fecundity down-regulation and changes in sex ratio. Estimates from both methods were similar in trend and absolute biomass. On the Dogger Bank, there was a dramatic decline in biomass from 1948 and 1950 to 2004, and in the Southern Bight, the stock appeared to increase from 1987 and 1988 to 2004, although not reaching the historically high levels of 1948 or 1950. The timing of spawning of North Sea plaice does not appear to have changed throughout the period of high exploitation. We conclude that the AEP method is a useful way to hindcast the spatial dynamics of heavily exploited flatfish stocks.

scholarly journals Modeling Discards in Stock Assessments: Red Grouper Epinephelus morio in the U.S. Gulf of Mexico

Fishes ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 7
Author(s):  
Kyle W. Shertzer ◽  
Erik H. Williams ◽  
Skyler R. Sagarese
Keyword(s):  
Gulf Of Mexico ◽  
Stock Assessment ◽  
Time Varying ◽  
Discard Mortality ◽  
Stock Assessments ◽  
Epinephelus Morio ◽  
Red Grouper ◽  
Management Advice ◽  
The U.S

To be as accurate as possible, stock assessments should account for discard mortality in fisheries if it occurs. Three common approaches to modeling discards in assessments are to lump dead discards with landings, treat dead discards as their own fleet, or link them conversely with landings through use of a retention function. The first approach (lumping) implicitly assumes that the selectivity of landings applies also to discards. In many cases, that assumption is false, for example, if discards comprise smaller fish than do landings. The latter two approaches avoid the assumption by modeling discards explicitly with their own selectivity pattern. Here, we examine these approaches to modeling discards. Using a simulation study, we demonstrate that the two approaches to modeling discards explicitly can provide identical results under both static and time-varying conditions. Then, using a stock assessment case study of red grouper Epinephelus morio in the U.S. Gulf of Mexico, we demonstrate that in practice the approaches to modeling discards can provide different outcomes, with implications for the resultant management advice. We conclude by comparing and contrasting the different approaches, calling for more research to elucidate which approach is most suitable under various sources of error typically encountered in discard data.

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