MPA Benefits - In Numbers
mtupper at guam.uog.edu
Thu Mar 7 18:53:02 EST 2002
By MPAs "enhancing fisheries stocks", I presume you mean increasing catches
to the point that the loss of fishing grounds is mitigated for, which is the
true test of whether or not an MPA actually enhances fisheries. There are
very few studies that have directly tested the role of MPAs in enhancing
fishery yields, but here are some useful references:
McClanahan TR, Kaunda-Arara B 1996. Fishery recovery in a coral-reef park
and its effect on the adjacent fishery.
McClanahan TR, Mangi S. 2000. Spillover of fishes from a marine park and its
effect on the adjacent fishery.
Both studies found evidence of spillover and increased CPUE/catch per unit
area from marine parks in Kenya, but concluded that "the catch per area
increase was insufficient to compensate for the lost area over this early
period of the park's establishment."
Roberts CM, Bohnsack JA, Gell F, Hawkins JP, Goodridge R. 2001. Effects of
marine reserves on adjacent fisheries. Science 294: 1920. (also see
responses to this article published in the Feb 15th issue of Science, vol
295, page 1733.)
Roberts et al found fishery-wide increases in catch per unit effort three to
five years after reserve implementation (CPUE dropped in the first two years
as fishing effort was concentrated into a smaller area).
Outside of the coral reef realm, there is strong evidence that the temporary
closure of the groundfish fishery on Georges Bank (NW Atlantic) greatly
increased spawning biomass of sea scallops. Go to www.seascallop.com and
click on "Closed Area Fishery".
Given that there are probably a couple of thousand MPAs in existence at this
point, there is precious little evidence to suggest that they can provide
the level of fisheries benefits claimed by many scientists. However, the
fact that most MPAs have failed to meet their management objectives is most
likely due to problems in their management (lack of institutional or
community capacity, poor enforcement, insufficient funding, lack of
technical expertise, etc.), as opposed to MPAs "not working" in a purely
ecological sense. Furthermore, even if they were managed effectively, many
MPAs are probably too new to show significant fisheries benefits.
You might want to read the following:
Alder J. 1996. Have tropical marine protected areas worked? An initial
analysis of their success. Coastal Management 24: 97-114.
McClanahan TR. 1999. Is there a future for coral reef parks in poor tropical
countries? Coral Reefs 18: 321-325.
In summary, there is very little direct evidence that "fisheries stocks are
enhanced by MPAs". This is for a number of reasons, including the following:
1. Studies directly testing the effects of MPAs on fisheries yields
have rarely been conducted or are not yet published.
2. Most MPAs are not sufficiently well-managed (i.e. they are "paper parks"
lacking enforcement, funding etc.) or are not old enough to meet their
Cheers and good luck with politicians etc.,
Dr. Mark Tupper, Assistant Professor
University of Guam Marine Laboratory
UOG Station, Mangilao
Guam 96923, USA
Tel. 671-735-2185; Fax 671-734-6767
Coordinator, Marine Protected Areas Research Group
More information about the Coral-list-old