17
An Age-Structured Model
of Fish Population Enhancement
Impl ications for Conservation
and Economic Sustainability
Richard Langton, James Lindholm, James Wilson,
and Sally Sherman
Traditionally, the marine biologists involved in management of fish
stocks have not been confronted with the question of economic return.
With the introduction of stock enhancement and especially sea ranching the situation is quite different.
A. Hallenstvedt, from Managementof Enhanced Stocks: Social,
Economic and Access Issues
In this chapter you will be:
• Introduced to a model combining biological processes and their direct
economic implications;
• Made aware of the potentially high sensitivity of economic profits to assumptions about basic life-history parameters.
17.1. Introduction
The addition of young fish to the ocean to enhance depleted populations
and to compensate for the exploitation of larger, commercially valuable animals is an alluring idea. It is also not a new idea, having been practiced
since the development of rearing techniques for various species of fish in
the nineteenth century (Shelbourne 1964). Many of the marine laboratories
in both the United States and Europe were , in fact, established as fish
hatcheries for the propagation and release of larval and juvenile fish to rectify a perceived demise of the local fish populations (Galtsoff 1962; Solemdal et al. 1984; Kirk 1987).
Efforts towards the enhancement of Atlantic cod, Gadus morhua, have
an especially long history, reflecting the importance of this species in the
European and North American fishing industry . In the US, efforts at revital376
M. Ruth et al. (Eds.), Dynamic Modeling for Marine Conservation
© Springer-Verlag New York, Inc. 2002
An Age-Structured Model
of Fish Population Enhancement
Impl ications for Conservation
and Economic Sustainability
Richard Langton, James Lindholm, James Wilson,
and Sally Sherman
Traditionally, the marine biologists involved in management of fish
stocks have not been confronted with the question of economic return.
With the introduction of stock enhancement and especially sea ranching the situation is quite different.
A. Hallenstvedt, from Managementof Enhanced Stocks: Social,
Economic and Access Issues
In this chapter you will be:
• Introduced to a model combining biological processes and their direct
economic implications;
• Made aware of the potentially high sensitivity of economic profits to assumptions about basic life-history parameters.
17.1. Introduction
The addition of young fish to the ocean to enhance depleted populations
and to compensate for the exploitation of larger, commercially valuable animals is an alluring idea. It is also not a new idea, having been practiced
since the development of rearing techniques for various species of fish in
the nineteenth century (Shelbourne 1964). Many of the marine laboratories
in both the United States and Europe were , in fact, established as fish
hatcheries for the propagation and release of larval and juvenile fish to rectify a perceived demise of the local fish populations (Galtsoff 1962; Solemdal et al. 1984; Kirk 1987).
Efforts towards the enhancement of Atlantic cod, Gadus morhua, have
an especially long history, reflecting the importance of this species in the
European and North American fishing industry . In the US, efforts at revital376
M. Ruth et al. (Eds.), Dynamic Modeling for Marine Conservation
© Springer-Verlag New York, Inc. 2002