Bioeconomic Module Scenarios and Outputs

This page summarises the main outputs of the Economic Module and examples of scenarios that can be explored.

For the mathematical formulation of the module, see Bioeconomic Module Mathematical Formulation. For parameters, see Bioeconomic Module Parameters. For the required input data, see Bioeconomic Module Data Requirements.

Output

The Economic Module can produce the following outputs:

• Total profit
• Total revenue
• Total costs
• Future prices

Total profit

Fishers' profit is the revenue from selling fish minus costs of harvesting:

$$ \Pi_{i,t} = \sum_{s} p_{i,s,t} h_{i,s,t} - C_{i,t} $$

The profit margin is the fraction of profits with respect to revenue:

$$ \pi_{i,t} = \frac{\sum_s p_{i,s,t} h_{is,t,} - C_{i,t}}{\sum_s p_{i,s,t} h_{is,t,}} $$

Total revenue

Total revenue is calculated from the biomass harvested from each species and size class and the corresponding prices:

$$ \sum_s p_{i,s,t} h_{i,s,t} $$

where $p_{i,s,t}$ is the price per kg and $h_{i,s,t}$ is the biomass harvested from each size class in a given year.

Total costs

The costs of harvesting fish increases with harvest and decreases when more fish are accessible.

$$ C_{i,t}=c_{i,t}\ \frac{H_{i,t}}{B_{i,t}^{\chi_i}}, $$

Here, $c_{i,t}$ are baseline harvesting costs that may increase (with increasing fuel prices) or decrease (with technological advancement) over time, such that $c_{i,t}=c_{i,0} e^{\tau_i(t-t_0)}$ with trend $\tau_i$. The parameter $\chi_i$ is the stock elasticity.

Future prices

Future prices are derived from the inverse demand function. Consumers maximise utility over the consumption of fish $h_{i,s,t}$, resulting in prices that depend on harvest, consumer preferences and substitution among size classes and species.

For the inverse demand equations, see Bioeconomic Module Mathematical Formulation.

Scenarios

The Economic Module can be used to explore scenarios such as:

• change harvest ($H_{i,t}$);
• change distribution of harvest over size classes;
• remove time trend ($\tau_i=0$);
• see what happens when consumers prefer larger or smaller fish by changing $\beta_{i,s}$.

Change harvest

A harvest scenario changes total harvest:

$$ H_{i,t} $$

This can be used to evaluate how different harvest levels affect costs, revenues, profits and future prices.

Change distribution of harvest over size classes

The distribution of harvest over size classes can be changed to explore the economic consequences of size-selective fishing.

When harvesting a total biomass of $H_{i,t}$, this is distributed to the size classes according to the retainment:

$$ h_{i,s,t}=q_{i,s}(\sigma_{i,t}) \ w_{i,s} \ N_{i,s,t}\frac{H_{i,t}}{B_{i,t}} $$

where $h_{i,s,t}$ is the biomass of fish harvested from each size class in a given year.

Remove time trend

A cost-trend scenario can remove the time trend in baseline harvesting costs:

$$ \tau_i=0 $$

This can be used to compare scenarios with and without changes in baseline harvesting costs over time.

Change consumer preferences

Consumer preferences for size classes are represented by:

$$ \beta_{i,s} $$

Changing $\beta_{i,s}$ can be used to see what happens when consumers prefer larger or smaller fish.

Related pages

• Bioeconomic Module
• Bioeconomic Module Concepts and Assumptions
• Bioeconomic Module Mathematical Formulation
• Bioeconomic Module Parameters
• Bioeconomic Module Data Requirements
• Bioeconomic Module Calibration
• Bioeconomic Module Examples