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Modelling the effect of introducing MPAS in a commercial fishery: a rock lobster example

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Haddon, M and Buxton, CD and Gardner, C and Barrett, NS (2002) Modelling the effect of introducing MPAS in a commercial fishery: a rock lobster example. In: World Congress on Aquatic Protected Areas , August 2002, Cairns, Australia.

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Abstract

The effect of introducing a large marine protected area (MPA) into a managed commercial fishery was
investigated using a spatially explicit, size-structured model. The stock dynamics approximated the biology
of Tasmanian rock lobsters in that adult movement was very limited while larval dispersal was widespread.
If an MPA displaces fishing effort into the area that remained open to fishing, then fishing mortality CF)
would be expected to rise. The effect of this increase in F would depend on the level of stock depletion, with
three possible main outcomes:
1. If the population was only lightly depleted and above the level of BMSY then fishing the open areas
harder increases the depletion level but Fenders the stock more productive. Depending on the exact level
of depletion and the increase in Fr a new equilibrium was reached.
2. Highly depleted population, below BMsY; fishing the stock harder depletes it further, making it even less
productive, if fishing maintained, leads to a fishery collapse.
3. If stock already close to collapse, then displaced effort would be so ineffective that the MPA could act to
increase recruitment levels and make the whole stock relatively more productive.
The model suggested that introducing large MPAs may be harmful without a reduction in catch at least
equivalent to that displaced from the MFA. An MFA without concomitant catch reduction could lead to
further stock depletion in open regions. This can lead to a new equilibrium or fishery collapse, depending
on the level of stock depletion when the MPA was introduced. If the fishery was close to or already
collapsed, an MFA was likely to be beneficial to stock recovery because of its contribution to recruitment.

Item Type: Conference or Workshop Item (Other)
Journal or Publication Title: Aquatic Protected Areas- What works best and how do we know? Proceedings of the World Congress on Aquatic Protected Areas Cairns, Australia- August 2002
Page Range: pp. 428-436
Additional Information:

Conference Title - Proceedings of the World Congress on Aquatic Protected Areas Cairns, Australia - August 2002

Date Deposited: 23 Feb 2011 05:17
Last Modified: 31 Mar 2011 00:44
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