Nomination for a World Heritage Site 2009 - Phoenix Islands ...

al 2004). Research suggests that these high rates are not just an artifact due to limited
sampling, for adjacent seamounts in New Caledonian waters have been found to share an
average of just 21% of their species, and seamounts on separate ridges approximately 1000
km apart in the Tasman and Coral Seas have only 4% of their species in common (Richer de
Forges et al. 2000. See also UNEP/CBD/COP/7/INF/25).
The biological characteristics of most deep-sea species associated with seamount ecosystems
render them particularly sensitive to human disturbance and exploitation. The slow growth,
longevity, late sexual maturity, and restricted distribution of many of these species (for
example, deep-sea corals, sponges and fish) make them particularly vulnerable to human
impacts and the risk of extinction. Concerns over the impact of fishing and the potential loss
of this biodiversity are amplified by the limited information about the taxonomy, biology and
ecology of most of the species found in deep ocean areas. Destructive fishing activities in
these areas could bring about extinctions of entire groups of organisms that are still
undiscovered (UNEP/CBD/COP/7/INF/25).
(From: www.cbd.int/doc/meetings/pa/pawg-01/information/pawg-01-inf-01-en.pdf)
In regards to the relevance of seamounts to pelagic ecology and fisheries, the summit depth
below the surface appears to be as important as the elevation above the sea floor. From this
point of view, seamounts can be classified into 3 classes (Anon., 2006)
(From: www.wcpfc.int/sc2/pdf/SC2_EB_IP5.pdf):
1) Shallow: summit reaching the euphotic zone
2) Intermediate: summit not reaching the euphotic zone but above the lower limit of
the Deep Scattering Layer (DSL), and
3) Deep: summit below the DSL.
Seamounts in Class 1 and 2 may be characterised by specific oceanographic features linked to
a more dynamic environment that will have a potential impact on the pelagic ecosystem and
fisheries exploiting it. Feeding is probably the main reason why large pelagics gather around
seamounts.
From information collected from exploratory cruises, benthic fauna on seamounts appears to
be characterised by a very high percentage of organisms previously unknown to science. The
high number of undescribed species makes it difficult to compare the biodiversity of different
seamounts or of continental slope and seamounts. Seamounts are different from continental
slopes and can be compared to islands as far as faunal biogeography is concerned; this has
been demonstrated with corals. Like oceanic islands, seamounts appear to be characterised by
a high level of endemism and closely adjacent seamounts can exhibit very distinctly different
benthic fauna with high degrees of local endemism.
The 2000 deep-sea surveys by New England Aquarium recorded the first distribution records
of sixgill (Hexanchus griseus) and Pacific sleeper (Somniosus pacificus) sharks for this part
of the Pacific from 900 meters depth near Kanton. It is probable that the seamounts of PIPA
have great importance for pelagic and commercially important fishery such as tuna and
skipjack. With 25% of the world’s seamounts already degraded the pristine seamounts of
PIPA provide critical protection for these fragile ecosystems and associated species,
representing a conservation resource of global significance.
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