Environmental and biological factors associated with the stage-specific abundance of brown shrimp (Penaeus aztecus) in Louisiana: applying a new combination of statistical techniques to long-term monitoring data

2001 ◽  
Vol 58 (11) ◽  
pp. 2258-2270 ◽  
Author(s):  
Heather L Haas ◽  
E Conrad Lamon III ◽  
Kenneth A Rose ◽  
Richard F Shaw
Keyword(s):  
Bayesian Model Averaging ◽  
Explanatory Power ◽  
Additive Models ◽  
Brown Shrimp ◽  
Small Scale ◽  
Nonlinear Relationships ◽  
Penaeus Aztecus ◽  
Juvenile Abundance ◽  
Abundance Estimates ◽  
Correlative Studies

Several short-term and small-scale correlative studies have associated brown shrimp (Penaeus aztecus) recruitment with high densities of sub-adults, high salinity, warm temperature, low river flow, and low precipitation. In this paper, we address criticisms of traditional correlative studies by using a spatially and temporally extensive dataset, by comparing stepwise multiple regression (SMR) to Bayesian model averaging (BMA), and by investigating nonlinear relationships with generalized additive models (GAMs). We use this combination of statistical methods to examine relationships between annual, stage-specific abundance estimates and environmental factors. BMA and SMR resulted in models with similar explanatory power, but BMA suggested fewer linear predictors. GAMs did not suggest nonlinear relationships among stage-specific abundance estimates. Postlarval abundance was not well described by any model. Juvenile abundance was partially described by environmental variables such as temperature, water clarity, and water level. Adult abundance was well described by early-juvenile abundance, salinity, and temperature. These results suggest that juvenile abundance may be the critical component in determining year-class strength of brown shrimp. Identifying mechanisms that regulate juvenile production within the estuary will be a critical step in effectively managing Louisiana's brown shrimp resource.

Hierarchical interpretation of nonlinear relationships linking yellowfin tuna (Thunnus albacares) distribution to the environment in the Atlantic Ocean

2001 ◽  
Vol 58 (3) ◽  
pp. 458-469 ◽  
Author(s):  
Olivier Maury ◽  
Didier Gascuel ◽  
Francis Marsac ◽  
Alain Fonteneau ◽  
Anne-Laure De Rosa
Keyword(s):  
Adult Population ◽  
Yellowfin Tuna ◽  
Additive Models ◽  
Small Scale ◽  
Physical Factors ◽  
Thunnus Albacares ◽  
Catch Per Unit Effort ◽  
Low Salinity ◽  
Nonlinear Relationships ◽  
Unit Effort

Using generalized additive models, we show evidence for nonlinear relationships between various hydrological factors and age-structured catch per unit effort of Atlantic yellowfin tuna (Thunnus albacares) for two fishing fleets. Catchability effects are distinguished from tuna environmental preference effects in the catch per unit effort variability. With respect to catchability, an important nonlinear effect of local fishing effort is highlighted for each fleet. It is interpreted as resulting from a local overfishing phenomenon of adult yellowfin tuna and from vessel fishing tactics (cooperation/spying). The environmental preferences obtained facilitate the interpretation of the hierarchical spatial distribution and age-dependent movements of the yellowfin population. We show that, on a large spatiotemporal scale (the whole ocean), low salinity is a good predictor of yellowfin habitat. Juveniles are mainly distributed in low-salinity waters (<0.035 kg·kg–1) when adults extend their range to waters of 0.036 kg·kg–1. On a mesoscale, adult population annual reproductive transatlantic displacements are probably driven by temperature and salinity gradients to warm and low-salinity locations that are favorable for juveniles. North–south seasonal movements of the population are clearly related to warmwater seasonal oscillations. On a small scale, ocean thermic stability and gradients of sea surface temperature are important physical factors determining yellowfin concentration.

scholarly journals Temporal trends in stock origin and abundance of juvenile herring (Clupea harengus) in the Irish Sea

2009 ◽  
Vol 66 (8) ◽  
pp. 1749-1753 ◽  
Author(s):  
Nóirín Burke ◽  
Deirdre Brophy ◽  
Pieter-Jan Schön ◽  
Pauline A. King
Keyword(s):  
Temporal Trends ◽  
Clupea Harengus ◽  
Irish Sea ◽  
First Year ◽  
Juvenile Abundance ◽  
Abundance Estimates ◽  
Otolith Microstructure Analysis ◽  
Celtic Sea ◽  
The Irish Sea ◽  
First Year Of Life

Abstract Burke, N., Brophy, D., Schön, P-J., and King, P. A. 2009. Temporal trends in stock origin and abundance of juvenile herring (Clupea harengus) in the Irish Sea. – ICES Journal of Marine Science, 66: 1749–1753. Celtic Sea herring (Clupea harengus) larvae partly disperse into the Irish Sea, where they mix with the resident stock during their first year of life. This affects the reliability of the use of acoustic estimates of juvenile abundance on the Irish Sea nursery grounds as a recruitment index for use in stock predictions. Otolith microstructure analysis can be used to distinguish between autumn-spawned and winter-spawned individuals. Because winter spawners do not occur in the Irish Sea, this component can be assigned to Celtic Sea immigrants. We used this method to estimate the proportion of winter-spawned individuals in samples of age-1 herring from the western Irish Sea over a 10-year period (1993–2003), and subtracted a corresponding proportion from the acoustic age-1 abundance estimates. The adjusted index for autumn-spawned (supposedly Irish Sea) juveniles was significantly correlated with the abundance of age-3 fish from the same year class in commercial catches and in the acoustic surveys (p < 0.05 and <0.01, respectively), whereas the correlations for unadjusted indices were not significant. These findings are discussed in relation to the monitoring and assessment of herring in the two areas.

DYNAMIC MODEL OF COMBINED AGGREGATION OF ADDITIVE MANUFACTURING PROCESS

2021 ◽  
Author(s):  
A. V. Vinnichenko ◽  
Keyword(s):  
Mathematical Modeling ◽  
Additive Manufacturing ◽  
Process Model ◽  
Additive Technologies ◽  
Additive Models ◽  
Small Scale ◽  
Scale Production ◽  
Flexible Production ◽  
Optimization Criteria ◽  
Production Resources

The paper presents methods and approaches for mathematical modeling and rationalization of flexible additive manufacturing, as well as other processes by which it is possible to create additive models for their integration into the system of experimental or pilot production. The work has also formed and synthesized a process model, which includes flexible production indicators, service indicators, and a developed criterion base for their assessment. The work takes into account the optimization criteria, as well as maximizing and minimizing risks for additive manufacturing, taking into account the possible risk component when deploying new processes for experimental and small-scale production. The models and methods described in the article will make it possible to carry out mathematical modeling and subsequent improvements for the flexible production process using additive technologies, used as a means of achieving the rational use of existing production resources within the framework of existing scientific and production complexes.

scholarly journals Microbial Flora of Pond-Reared Brown Shrimp (Penaeus aztecus) 1

1971 ◽  
Vol 21 (5) ◽  
pp. 916-921
Author(s):  
C. Vanderzant ◽  
R. Nickelson ◽  
P. W. Judkins
Keyword(s):  
Microbial Flora ◽  
Brown Shrimp ◽  
Penaeus Aztecus

scholarly journals Essential habitat for sardine juveniles in Iberian waters

2017 ◽  
Vol 81 (3) ◽  
pp. 351 ◽  
Author(s):  
Sílvia Rodríguez-Climent ◽  
Maria Manuel Angélico ◽  
Vítor Marques ◽  
Paulo Oliveira ◽  
Laura Wise ◽  
...  
Keyword(s):  
Fishery Management ◽  
Generalized Additive Models ◽  
Management Strategies ◽  
Coastal Region ◽  
Additive Models ◽  
Spawning Grounds ◽  
Significant Relationships ◽  
Juvenile Abundance ◽  
Spatial Differences ◽  
Core Areas

In a period when the Iberian sardine stock abundance is at its historical minimum, knowledge of the sardine juvenile’s distribution is crucial for the development of fishery management strategies. Generalized additive models were used to relate juvenile sardine presence with geographical variables and spawning grounds (egg abundance) and to model juvenile abundance with the concurrent environmental conditions. Three core areas of juvenile distribution were identified: the Northern Portuguese shelf (centred off Aveiro), the coastal region in the vicinity of the Tagus estuary, and the eastern Gulf of Cadiz. Spatial differences in the relationship between juvenile presence and egg abundances suggest that essential juvenile habitat might partially differ from the prevailing spawning grounds. Models also depicted significant relationships between juvenile abundance, temperature and geographical variables in combination with salinity in the west and with zooplankton in the south. Results indicate that the sardine juvenile distribution along the Iberian Peninsula waters are an outcome of a combination of dynamic processes occurring early in life, such as egg and larva retention, reduced mortality and favourable feeding grounds for both larvae and juveniles.

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