[Coral-List] Pelagic MPAs

dfenner dfenner dfenner at blueskynet.as
Mon Nov 1 16:37:05 EDT 2010

       In my message about pelagic MPAs such as Chagos, I ended asking if
these issues had been considered in planning for large pelagic MPAs, and
inviting their authors to educate us.  I thank my colleagues for beginning
the process of educating me on this.  Indeed for the Chagos MPA there is
quite a bit of information to support the role of pelagic MPA’s.  I list
several references at the end of this message that give a great deal of
information on the topic.  In particular, the article by Sibert and Hampton
say ‘‘the median lifetime displacement of skipjack ranges from 420 to 470
nautical miles. The lifetime displacement of yellowfin is about 20%
less”.  Also
‘‘The term, ‘highly migratory’ appears to have no operational definition in
relation to the natural history of tunas. Rather, it is a legal term defined
only in the context of the Law of the Sea.” Further: ‘‘. . .the results also
suggest that Pacific Island countries can implement effective domestic
management policies to promote conservation and sustainable utilization of
tuna stocks within their EEZs”.  They present a map of the western Pacific
from the Philippines to American Samoa that shows that most of that area is
within the EEZ’s of various countries there (a map of the whole Pacific
would show that a majority of the Pacific is not in any EEZ).  They report
that only 20% of the tuna catch in the western and central Pacific Ocean is
taken outside of EEZ’s.  Thus, the EEZ’s could be a very effective tool for
managing stocks of those two species in that area, and could be for the
Pacific in general.  The new Chagos reserve is about 450 nautical miles in
diameter, so it should have at least some effect on pelagic stocks within
it.  On the other hand, Sibert and Hampton also say “The biological
characteristics of tropical skipjack and yellowfin tunas estimated in this
study are such that their movements will carry a significant proportion of
the population beyond most EEZs during their lifetime. Some degree of
cooperation between neighboring states would, therefore, appear to be
essential for conservation and optimal exploitation of skipjack and
yellowfin stocks.”  Clearly, such international cooperation in the Pacific
could be between nations with adjacent EEZ’s, and would not require the
agreement of all nations in the regional tuna councils or the distant water
fishing nations.  They argue that both local management within a country’s
EEZ and international management are needed.  The Koldewey et al. (2010)
paper lists several studies that have documented the positive effects of
MPAs on migratory species.  The Koldewey paper has far too much information
in it to summarize succinctly and I highly recommend that it be read.

      I note that if a pelagic MPA is large enough to cover much of the
range of a migratory species, but can’t cover it all, the situation appears
to be quite parallel to a small MPA on a coral reef, where fish moving
outside the MPA are called “spillover” and can increase fish catches in
areas around the MPAs.  In terms of fisheries, MPA’s could be considered as
natural fish farms, though their ecosystem protection benefits are much
broader than that.

      I do not have similar information on the migratory range of other
pelagic species such as Bigeye and albacore tuna, or sharks, swordfish,
marlin, wahoo, etc.  Based on the two we do have data on, the precautionary
approach would be to assume they have similar sorts of ranges.  The Koldewey
paper indicates a third tuna species has a similar range, indicating that is
probably a good assumption.

     My colleague rightly reminds me that these large pelagic MPAs often
have many seamounts in them.  Seamounts often concentrate some types of sea
life, including tuna (as pointed out in the Koldewey paper).  Further,
trawling on seamounts which can catch huge quantities of long-lived fish
such as orange roughy, effectively mining them much faster than they can
reproduce, also is highly destructive to benthic communities such as deep
coral beds.

      The Sibert & Hampton paper, and the Koldewey et al paper do not
consider the problems of enforcement in detail. Koldewey et al. say
that “although
some of the challenges relating to their implementation may be both costly
and difficult (Kaplan et al., 2010).”  The Game et al (2009) paper does
consider the enforcement problem, but I have not yet been able to access
this paper.  As I pointed out in my previous message, VMS (vessel monitoring
systems, a GPS and satellite system for remotely tracking ship movements) is
widespread in tuna fleets, though I don’t know how widely it is required.  Such
a system is very feasible (it would be too costly for small artisinal boats
but a minor cost for industrial tuna ships, which are probably the main
concern for remote pelagic MPAs).  If tuna fishing boats are excluded from
these MPAs, it would be relatively easy to track them continuously if they
have VMS on them.  A patrol boat could then intercept any found within the
MPA.  This won’t stop boats that do not have VMS and poachers certainly
wouldn’t have VMS (illegal fishing is a problem everywhere).  Compliance is
always the goal of enforcement, and simply having the capability to catch
violators and an occasional apprehension of one and punishment can produce
good compliance, which in turn greatly reduces the logistics and costs of
enforcement, as well as achieving the objectives.  So perhaps it may not be
as difficult as I imagined.

      The views I expressed in my previous message were taken virtually
verbatim from meetings of the Scientific and Statistical Committee of the
Western Regional Fisheries Management Council in Honolulu, in 2004 and early
2005.  I note that the Sibert and Hampton article which reported that
Skipjack and Yellowfin tuna have median lifetime migrations of only about
420-470 km, was published in 2003.  Sibert was a member of that committee
and I remember him present at most of the meetings I attended, though
perhaps not at the particular meeting where that was discussed.  Yet, no
opinions contrary to the ones I heard and put in my message were expressed
then.  Bit surprising.        Doug

The Koleway and Sibert articles are available free online, just search for
them on Google Scholar.

Game, E.T., Grantham, H.S., Hobday, A.J., Pressey, R.L., Lombard, A.T.,
Beckley, L.E.,

Gjerde, K., Bustamante, R., Possingham, H.P., Richardson, A.J., 2009.

protected areas: the missing dimension in ocean conservation. Trends Ecol.

Evol. 24 (7), 360–369.

Koldewey, H., Curnick, D., Harding, S., Harrison, L., Gollock, M., 2010.

benefits to fisheries and biodiversity of the Chagos Archipelago/British

Ocean Territory as a no-take marine reserve. Marine Pollution Bulletin 60,


Sheppard, C.  2010.  Marine protected areas and pelagic fishing: The case of
the Chagos Archipelago.  Marine Pollution Bulletin 60: 1899-1901.

Sibert, J., Hampton, J., 2003. Mobility of tropical tunas and the
implications for

fisheries management. Mar. Policy 27, 87–95.

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