scholarly journals Validating management simulation models and implications for communicating results to stakeholders

2007 ◽  
Vol 64 (4) ◽  
pp. 818-824 ◽  
Author(s):  
Martin A. Pastoors ◽  
Jan Jaap Poos ◽  
Sarah B. M. Kraak ◽  
Marcel A. M. Machiels
Keyword(s):  
North Sea ◽  
Simulation Models ◽  
Management Plan ◽  
Level Of Detail ◽  
Advisory Council ◽  
The North ◽  
Management Procedure ◽  
Management Plans ◽  
The North Sea ◽  
Fleet Dynamics

Abstract Pastoors, M. A., Poos, J. J., Kraak, S. B. M., and Machiels, M. A. M. 2007. Validating management simulation models and implications for communicating results to stakeholders. – ICES Journal of Marine Science, 64: 818–824. Simulations of management plans generally aim to demonstrate the robustness of the plans to assumptions about population dynamics and fleet dynamics. Such modelling is characterized by specification of an operating model (OM) representing the underlying truth and a management procedure that mimics the process of acquiring knowledge, formulating management decisions, and implementing those decisions. We employ such a model to evaluate a management plan for North Sea flatfish proposed by the North Sea Regional Advisory Council in May 2005. Focus is on the construction and conditioning of OMs, key requirements for such simulations. We describe the process of setting up and validating OMs along with its effects on the ability to communicate the results to the stakeholders. We conclude that there is tension between the level of detail required by stakeholders and the level of detail that can be provided. In communicating the results of simulations, it is necessary to make very clear how OMs depend on past perceptions of stock dynamics.

Prediction of Relative Motion and Probability of Contact Between FPSO and Shuttle Tanker in Tandem Offloading Operation

2002 ◽  
Author(s):  
Haibo Chen ◽  
Torgeir Moan ◽  
Sverre Haver ◽  
Kjell Larsen
Keyword(s):  
North Sea ◽  
Extreme Values ◽  
Simulation Models ◽  
Point Of View ◽  
Simulation Code ◽  
The North ◽  
Simulation Based ◽  
The North Sea ◽  
Sensitivity Studies ◽  
Tandem Offloading

Tandem offloading safety between FPSO and shuttle tanker is under concern. A few collisions between the two vessels have happened in the North Sea in recent years. In these incidents, excessive relative motions (termed as surging and yawing in this paper) between FPSO and tanker are identified as “failure prone situations” which have contributed to the initiation of most collision incidents. To quantitatively assess the probability of surging and yawing events, and more importantly, to effectively reduce their occurrence in tandem offloading operation, we present a simulation-based approach in this paper, which is carried out by a state-of-the-art time-domain simulation code SIMO. The SIMO simulation models are setup and calibrated for a typical North Sea purpose-built FPSO and a DP shuttle tanker. This 2-vessel system motion in tandem offloading is simulated. The simulated relative distance and relative heading between FPSO and tanker are analyzed by fitting their extreme values into statistical models. This gives out probabilities of surging and yawing events. Sensitivity studies are performed to analyze contributions from various technical and operational factors. Measures to minimize the occurrence of surging and yawing from design and operational point of view are proposed.

scholarly journals Modelling combined harvest and effort regulations: the case of the Dutch beam trawl fishery for plaice and sole in the North Sea

2008 ◽  
Vol 65 (6) ◽  
pp. 822-831 ◽  
Author(s):  
A. Hoff ◽  
H. Frost
Keyword(s):  
North Sea ◽  
Stock Assessment ◽  
Beam Trawl ◽  
Trawl Fishery ◽  
The North ◽  
Feedback Model ◽  
Economic Operation ◽  
The North Sea ◽  
Fishing Fleets ◽  
Fleet Dynamics

Abstract Hoff, A. and Frost, H. 2008. Modelling combined harvest and effort regulations: the case of the Dutch beam trawl fishery for plaice and sole in the North Sea. – ICES Journal of Marine Science, 65: 822–831. Currently, several European fishing fleets are regulated through a combination of harvest and effort control. The two regulation schemes are interrelated, i.e. a given quota limit will necessarily determine the effort used, and vice versa. It is important to acknowledge this causality when assessing combined effort and harvest regulation systems. A bioeconomic feedback model is presented that takes into account the causality between effort and harvest control by switching back and forth between the two, depending on which is the binding rule. The model consists of a biological and an economic operation module, the former simulating stock assessment and quota establishment, and the latter simulating the economic fleet dynamics. When harvest control is binding, catch is evaluated using the biological projection formula, whereas the economics-based Cobb–Douglas production function is used when effort is binding. The method is applied to the Dutch beam trawl fishery for plaice and sole in the North Sea.

Prediction of Relative Motion and Probability of Contact Between FPSO and Shuttle Tanker in Tandem Offloading Operation

2003 ◽  
Vol 126 (3) ◽  
pp. 235-242 ◽  
Author(s):  
Haibo Chen ◽  
Torgeir Moan ◽  
Sverre Haver ◽  
Kjell Larsen
Keyword(s):  
North Sea ◽  
Extreme Values ◽  
Simulation Models ◽  
Time Domain Simulation ◽  
Simulation Code ◽  
The North ◽  
Simulation Based ◽  
The North Sea ◽  
Sensitivity Studies ◽  
Tandem Offloading

Excessive relative motions between Floating Production Storage Offloading Unit (FPSO), and tanker, which are termed as excessive surging and yawing events, are identified as the “failure prone situation” in tandem offloading. These events have contributed to the initiation of tanker drive-off in most collision incidents that happened in the North Sea in recent years. To estimate and reduce the probability of excessive surging and yawing events in tandem offloading, a simulation-based approach, which is based on a state-of-the-art time-domain simulation code SIMO, is presented in this paper. A typical North Sea FPSO and a DP shuttle tanker simulation models are setup in SIMO and calibrated by full-scale measurements. The simulated relative distance and relative heading between FPSO and tanker are analyzed by fitting their extreme values into statistical models which give out probabilities of excessive surging and yawing events. Sensitivity studies are performed to pinpoint contributions from various technical and operational factors. Measures to minimize the occurrence of excessive surging and yawing events are identified in design and operational perspectives.

Recent Changes in the Central and Southern North Sea Herring Stocks

1985 ◽  
Vol 42 (S1) ◽  
pp. s192-s206 ◽  
Author(s):  
A. C. Burd
Keyword(s):  
North Sea ◽  
Maximum Yield ◽  
Total Allowable Catch ◽  
Underlying Assumption ◽  
Southern North Sea ◽  
The North ◽  
Management Procedure ◽  
Stock Biomass ◽  
Spawning Stock ◽  
The North Sea

Since 1980 there has been a sudden recovery of recruitment to the central and southern North Sea herring stocks (Bank and Downs, respectively). In contrast, recruitment to the northern North Sea has continued at a low level and spawning stock biomass has even declined since 1979. These events underline the independence of the substocks in the North Sea, each of which has reacted differently to the cessation of the directed herring fishery in the North Sea since 1977. A precondition to the reopening of a herring fishery in the North Sea was that the severely depleted spawning stock biomass should have recovered to 800 000 t, the underlying assumption being that all components would respond in a similar manner and that a reopening of the whole North Sea would be possible. This has not happened and it may well be that management of the North Sea as a single unit is not a viable management procedure. The paper examines the historic changes in sizes of the Bank and Downs stocks, with particular emphasis on the most recent period. Evidence of density-dependent growth change is considered together with the recent data on fecundity and larval herring production. It is concluded that if the separate stocks are to be managed individually for maximum yield, then global North Sea regulations such as a total allowable catch and size regulation are inappropriate. Regulations must also take into consideration the seasonal distributions of the stocks. Indeed, this would lead, in particular, to more restrictive and specific regulation of the industrial fisheries.

RESULTS OF THE 1987 FORTIES CRUDE OIL TRIAL IN THE NORTH SEA

1989 ◽  
Vol 1989 (1) ◽  
pp. 525-532 ◽  
Author(s):  
N. Hurford ◽  
I. Buchanan
Keyword(s):  
Physical Properties ◽  
Crude Oil ◽  
North Sea ◽  
Oil Spill ◽  
Simulation Models ◽  
The North ◽  
Surface Samples ◽  
The North Sea

ABSTRACT This report presents the results of a trial to study the behavior of Forties crude oil spilled at sea. The trial involved the release of approximately 20 metric tons (t) of Forties crude oil and monitoring the movement, spreading, and dispersion of the slick over a four-day period. Surface samples were collected at regular intervals to determine changes in the physical properties of the oil. The implications of the results for the development of oil spill simulation models are discussed.

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