14
Dynamics of Multiple Fish Species
Under Variable Levels of Exploitation
1
Matthias Ruth and James Lindholm
It is within the power of industry to increase productivity while protecting biological diversity, and to proceed in a way that one leads to the
other.
Edward O . Wilson, from The Diversity of Life
In this chapter you will:
• Examine the interaction of three fish species-cod, haddock, and pollock-under variable levels of exploitation;
• Investigate the impact of economic changes in a fishery on a multispecies fish assemblage;
• Investigate the impact of different management measures on a multispecies fish assemblage and the associated fishery.
14.1. Introduction
Marine fish populations are among the most heavily exploited populations
on Earth. Fish populations are subject to the fluctuations of numerous environmental factors and to economic changes within the fishing industry that
are all but steady over time. The cumulative effect of these influences upon
fish populations has left commercial fisheries around the globe struggling
to adjust to precipitously declining fish populations, while simultaneously
striving to maintain economic viability and cultural identity in the fishing
communities involved (World Resources Institute 1994).
The groundflshery on Georges Bank (northwest Atlantic) is a particularly apt example of a collapsing fishery. Fluctuations in the composition of
species in an assemblage, environmental conditions, predator-prey relation, and the complexity of economic adjustment processes all contribute to
scientific uncertainty in fish population dynamics. Management decisions
lPreviously published in expanded form as: Ruth, M. and J. Lindholm. (1997). Dynamic Modeling of Multispecies Fisheries for Consensus Building and Management.
Environmental Conservation 23: 332-342.
314
M. Ruth et al. (Eds.), Dynamic Modeling for Marine Conservation
© Springer-Verlag New York, Inc. 2002
Dynamics of Multiple Fish Species
Under Variable Levels of Exploitation
1
Matthias Ruth and James Lindholm
It is within the power of industry to increase productivity while protecting biological diversity, and to proceed in a way that one leads to the
other.
Edward O . Wilson, from The Diversity of Life
In this chapter you will:
• Examine the interaction of three fish species-cod, haddock, and pollock-under variable levels of exploitation;
• Investigate the impact of economic changes in a fishery on a multispecies fish assemblage;
• Investigate the impact of different management measures on a multispecies fish assemblage and the associated fishery.
14.1. Introduction
Marine fish populations are among the most heavily exploited populations
on Earth. Fish populations are subject to the fluctuations of numerous environmental factors and to economic changes within the fishing industry that
are all but steady over time. The cumulative effect of these influences upon
fish populations has left commercial fisheries around the globe struggling
to adjust to precipitously declining fish populations, while simultaneously
striving to maintain economic viability and cultural identity in the fishing
communities involved (World Resources Institute 1994).
The groundflshery on Georges Bank (northwest Atlantic) is a particularly apt example of a collapsing fishery. Fluctuations in the composition of
species in an assemblage, environmental conditions, predator-prey relation, and the complexity of economic adjustment processes all contribute to
scientific uncertainty in fish population dynamics. Management decisions
lPreviously published in expanded form as: Ruth, M. and J. Lindholm. (1997). Dynamic Modeling of Multispecies Fisheries for Consensus Building and Management.
Environmental Conservation 23: 332-342.
314
M. Ruth et al. (Eds.), Dynamic Modeling for Marine Conservation
© Springer-Verlag New York, Inc. 2002