EconMult
Encyclopedia
EconMult is a general fleet
model to be used in fisheries
modelling. EconMult has been developed since 1991 as a part of the Multispecies management programme by the Norwegian Research Council at the Norwegian College of Fishery Science
(University of Tromsø
, Norway
).
simulation
model where the fleet activity is controlled by two variables
: Number of vessels (v) (within each fleet segment) and Number of fishing days d) (within each time interval). The biomass units (x) are exogenous variables. The model resolution is determined by four structural variables: Number of fleet groups j), Number of targeted species n), Number of biomass units i) (which may be more than one within each targeted species) and Period length (time step in the simulation). The number of vessels and fishing days therefore are presented in fleet (columns)-targeted species (rows) matrices, while the biomass units is presented in a column vector (X):
production function
, applying two input variables: Number of fishing days d) and Biomass unit x). In the matrix below each column represents a fleet group and each row a targeted species so each element in the matrix is a fishery and gives the vessel catch of the biomass units represented. The biomass units represent all the targeted species. Each catch is represented a Cobb-Douglas production equation as shown in the vessel yield matrix (Y):
The corresponding fleet catches are
α β and q are parameters, the first two known as output elasticities of effort and biomass respectively, q is often referred to as the catchability coefficient. All the three parameters have the same dimension as the matrix above, e.g. the catchability coefficient:
packages related to EconMult:
Fishing fleet
A fishing fleet is an aggregate of commercial fishing vessels. The term may be used of all vessels operating out of a particular port, all vessels engaged in a particular type of fishing , or all fishing vessels of a country or region.Although fishing vessels are not formally organized as if they...
model to be used in fisheries
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
modelling. EconMult has been developed since 1991 as a part of the Multispecies management programme by the Norwegian Research Council at the Norwegian College of Fishery Science
Norwegian College of Fishery Science
The Norwegian College of Fishery Science was established in 1972 as a joint responsibility of the three Norwegian universities in Tromsø, Bergen and Trondheim...
(University of Tromsø
University of Tromsø
The University of Tromsø is the world's northernmost university. Located in the city of Tromsø, Norway, it was established in 1968, and opened in 1972. It is one of eight universities in Norway. The University of Tromsø is the largest research and educational institution in northern Norway...
, Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
).
Model resolution and key variables
EconMult is a discrete timeDiscrete time
Discrete time is the discontinuity of a function's time domain that results from sampling a variable at a finite interval. For example, consider a newspaper that reports the price of crude oil once every day at 6:00AM. The newspaper is described as sampling the cost at a frequency of once per 24...
simulation
Simulation
Simulation is the imitation of some real thing available, state of affairs, or process. The act of simulating something generally entails representing certain key characteristics or behaviours of a selected physical or abstract system....
model where the fleet activity is controlled by two variables
Variable (mathematics)
In mathematics, a variable is a value that may change within the scope of a given problem or set of operations. In contrast, a constant is a value that remains unchanged, though often unknown or undetermined. The concepts of constants and variables are fundamental to many areas of mathematics and...
: Number of vessels (v) (within each fleet segment) and Number of fishing days d) (within each time interval). The biomass units (x) are exogenous variables. The model resolution is determined by four structural variables: Number of fleet groups j), Number of targeted species n), Number of biomass units i) (which may be more than one within each targeted species) and Period length (time step in the simulation). The number of vessels and fishing days therefore are presented in fleet (columns)-targeted species (rows) matrices, while the biomass units is presented in a column vector (X):
 |  |  |   |
Catch production
A Fishery is in EconMult defined as a unique Fleet/Targeted species combination. The total catch within each fishery may include all biomass units defined in the model. Each biomass unit vessel catch is computed by Cobb-DouglasCobb-Douglas
In economics, the Cobb–Douglas functional form of production functions is widely used to represent the relationship of an output to inputs. Similar functions were originally used by Knut Wicksell , while the Cobb-Douglas form was developed and tested against statistical evidence by Charles Cobb and...
production function
Production function
In microeconomics and macroeconomics, a production function is a function that specifies the output of a firm, an industry, or an entire economy for all combinations of inputs...
, applying two input variables: Number of fishing days d) and Biomass unit x). In the matrix below each column represents a fleet group and each row a targeted species so each element in the matrix is a fishery and gives the vessel catch of the biomass units represented. The biomass units represent all the targeted species. Each catch is represented a Cobb-Douglas production equation as shown in the vessel yield matrix (Y):
The corresponding fleet catches are
α β and q are parameters, the first two known as output elasticities of effort and biomass respectively, q is often referred to as the catchability coefficient. All the three parameters have the same dimension as the matrix above, e.g. the catchability coefficient:
Downloads
MathematicaMathematica
Mathematica is a computational software program used in scientific, engineering, and mathematical fields and other areas of technical computing...
packages related to EconMult: