comparisons of fished vs. unfished nautilid populations
TRANSCRIPT
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New reflections on old data: living populations of Nautilus and Allonautilus
W. Bruce Saunders and Peter D. Ward
Bryn Mawr College, Department of Geology, Bryn Mawr, PA; University of Washington, Department of Zoology, Seattle, WA
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From the NY Times, Oct 25, 2011
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Shells of the species of Allonautilus/Nautilus
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Ngemelis Is., Palau. Typical Indo‐Pacific Nautilus‐Allonautilus habitat, with animals scavengngforeef slopes at depths of ~100‐500 m, moving into shallower water during darkness.
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Trap with N. belauensis being retrieved from ca. 300m in 1984. ~30% of the animals had been previously tagged & released (some were recaught five times).
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Republic of Palau (Belau), W. Caroline Is.
Locs. B & D were primary trapping sites for N. belauensis during 1977‐1985, when ~ 2,500 animals were trapped, tagged and
released.
Four animals were recaptured after 10‐12mos, 40‐150 km away (~0.5km/day).
An empty N. belauensis shell was recovered in Mindanao, Philippines, 138 days after being tagged (~7 km/day).
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Deep‐water remote camera setup, used to ~ 500m depth. In Palau, Philippines & Papua New Guinea. Bottom, scenes from Palau, 273m (left) and 500m (right).
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Summary composite of depth‐limiting factors, based on deep‐water photosequenceand trapping data in Palau, but representative of Nautilus/Allonautilus generally.
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RV Alpha Helix Nautilus research expedition to the Philippines, 1979. Typical Nautilus fishery efforts, off Negros Is., and deep‐water camera photos, ca. 220m depth.
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Nautilus/Allonautilus trapping in PNG. Left, sites where living populations were found, showing 1000m depth contour; top right, Ndrova Is., Manus, where first Allonautilus were trapped in 1986; bottom, first trap containing N. pompilius and A. scrobiculatus.
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Closeups of Nautilus/Allonautilus at Ndrova Is., Manus, PNG. Lower right, deep‐water remote photograph of both genera in trap with deep‐water snapper (Etelis carbunculus)
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Lizard Is., GBR; first living N. stenomphalus (lower left) and sympatric N. pompilius (right).
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Top: Ambon, Indonesia, type locality of N. p. pompilius s. s. described by Rumphius (1705) and cited by Linnaeus (1758). Bottom: first N. pompilius trapped off Pago Pago, American Samoa (left), and empty traps being retrieved in W. Samoa (also, Tonga, Kosrae, Yap, Pohnpei…..
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Should Nautilus/Allonautilus be protected?
Intense fishing has depleted N. pompilius populations at some Philippine localities. Population replenishment will occur, if left alone.
• There are thousands of un‐touched N. pompilius populations in the Indo‐Pacific.
• Sustainability via mariculture is probably not feasible. Drifted shells, (e.g.,killed by Octopus) could provide “green” material to the shell trade, at no cost to the parent population.
• My personal greatest concern is for the endemic species, which also happen to be the most profitable. These species (N. stenomphalus, N. belauensis, N. p. suluensis, N. repertus?, A. scrobiculatus, and A. perforatus?) are vulnerable, and should be protected. For now, N. pompilius s.l., as presently understood, probably does not need protection (?).
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I
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Octopus predation on Nautilus. Deep‐water photograph of Octopus sp. on Nautilus trap, and shell borings. Lower left, composite location of borings in 50% of 1,532 empty shells of N. pompilius.
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Nautilus/Allonautilus Populations & Abundance:Relevant Factors
• Geographic & hydrographic isolation (implosion >800m)• Water temperature (< ~21C)• Growth rate (~5‐10yr to maturity)• Reproductive rate (iteroparity; 1‐2 eggs; ~ 1yr to hatching)• Life span (~10‐20yr?)• Mature:immature ~4:1; male:female ~3.5:1• Trapping susceptibility (~30% recatch rate)• Habitat availability (no problem)• Mariculture dubious (growth rate; clean, cold water)• Sustainability (dead, Octopus‐drilled shells)
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Should Nautilus/Allonautilus be protected?
• It was recently proposed that Nautilus/Allonautilus (N/A) should be approved for CITES protection (Convention on International Trade in Endangered Species).
• This was bolstered, in part, by a USF & W report that 579,000 Nautilus shells had been imported into the U. S. (2005‐2008) (?).
• The CITES proposal was considered & tabled, pending additional information on population sizes and fisheries pressure.
• There is definitely greater awareness that there are several species of “chambered nautilus.” Some bring higher prices, particularly larger shells. So‐called Nautilus “pearls” are even being marketed.
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Distribution of known living populations of Nautilus/Allonautillus, and constituent species
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BRUV being deployed, GBR
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“BRUV” apparatus (Baited Underwater Remote Vehicle) on GBR
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“BRUV” apparatus (Baited Underwater Remote Vehicle) on GBR
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Loving the Chambered Nautilus to DeathOctober 25, 2011
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Distribution of known living populations of Nautilus/Allonautillus, and constituent species
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Recaptured N. belauensis ; this animal had been fully mature when released four years earlier.
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Recaptured submature N. belauensis showing one years’ shell growth.
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Tagged N. belauensis after release at Ngemelis, Palau, being attacked by triggerfish (Balistoides).
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Same N. belauensis as in previous slide, after repeated triggerfish attacks. Note that animal had been recaptured three times.
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From Bonacum et al. 2011
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BRUV image off Lizard Is., GBR (ca. 200m)
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BRUV image off Lizard Is., GBR (ca. 200m)