Ecologically or Biologically Significant Areas (EBSAs)
published:16 Aug 2016
Emperor Seamount Chain and Northern Hawaiian Ridge
The Emperor Seamount Chain and Northern Hawaiian Ridge stretch from the Aleutian Trench to the northwestern Hawaiian Islands across the North Pacific Basin (Figure 1). This is a series of seamounts in the area beyond US national jurisdiction (Figures 2 and 3). Many of the seamounts in the area have been fully utilized by the commercial fishery since 1967. Currently, bottom fisheries in the area are managed by interim conservation measures of the North Pacific Fisheries Commission (NPFC) and voluntary measures of NPFC participants, including capacity limits, effort control, time-area closures, and deployment of vessel monitoring systems and onboard scientific observers.
The Emperor Seamount Chain and Northern Hawaiian Ridge stretch from the Aleutian Trench to the northwestern Hawaiian Islands across the North Pacific basin (Figure 1). A series of seamounts outside the US EEZ (Figures 2 and 3) comprise an area meeting EBSA criteria. Many of the seamounts in the area have been fully utilized by the commercial fishery since 1967. However, bottom fisheries in the area are currently managed by interim conservation measures of the North Pacific Fisheries Commission (NPFC) and voluntary measures of participants of the NPFC, including capacity limits, effort control, time-area closure, and deployment of vessel monitoring systems and onboard scientific observers. Scientific surveys of commercial fish species, and benthic habitat and fauna have been conducted by some NPFC participants. Results of the scientific activities have been submitted to the Scientific Working Group of the NPFC. Former assessment reports are available from the NPFC website (http://nwpbfo.nomaki.jp/Assessment.html). Scientific information collected by these activities indicated that the area has moderate uniqueness, special importance for life-history stages of some species, vulnerability, biological productivity, and biological diversity relative to the surrounding deep sea floor.
Emperor Seamount Chain and Northern Hawaiian Ridge stretch for ca. 3000 km from the Aleutian Trench to the northwestern Hawaiian Islands in the western North Pacific Ocean (53-30°N, 164-177°E).
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Physical characteristics: The Emperor Seamounts and Northern Hawaiian Ridge were formed as volcanic hotspot tracks as the Pacific tectonic plate moved over a mantle magma source (Wilson 1963, Sharp and Clague 2006, Stock 2006). The seamounts get progressively younger from north to south (85-30 million years old). Most of the seamounts in this region are classified as guyots (Smoot 1991). Topography of a guyot is characterized by flat plateau, upper slope and flanking slope near the base. Hard substrate on exposed top, ledges and slopes, and ledges and soft sediments on depressions provide habitats for some benthic organisms. The minimum depths of the seamounts range approximately 300 m to 2000 m, and southern seamounts are generally shallower than northern seamounts (Smoot 1985, 1986, 1991, Table 1). The chain of seamounts creates an oceanographical boundary and mesoscale eddies in the upper water column, and attract some pelagic species (Yasui 1986, Boehlert 1988). Utilization by fishery: Most of the seamounts in the area have been utilized by commercial fisheries since 1967, and biological information on fish and benthos has been collected through scientific surveys, exploratory fisheries, and scientific observers onboard commercial vessels. North Pacific armorhead (Pseudopentaceros wheeleri) and Splendid alfonsin (Beryx splendens) are major target species in demersal fisheries in the Emperor Seamounts/Northern Hawaiian Ridge area (Fisheries Agency of Japan 2008 Appendices D and E). The North Pacific armorhead utilizes southern seamounts in this area as adult habitat and spawning ground, whereas larvae and juvenile are widely distributed in the epipelagic zone of the North Pacific Ocean (Fisheries Agency of Japan 2008 Appendix E). Splendid alfonsin is supposed to have a meta-population structure in the whole North Pacific Ocean, since there is no genetic differentiation within the ocean, and larvae can be transported from the Japanese archipelago to the Emperor Seamounts/Northern Hawaiian Ridge via the Kuroshio and Kuroshio Extension Currents. Both species mature in three to four years and are moderately fecund and productive (Fisheries Agency of Japan 2008 Appendix D). Productivity of these two species is relativiely higher than those of typical deepwater fish species, such as orange roughy (Hoplostethus atlanticus) and sablefish (Anoplopoma fimbria), which have extremely slow growth rates, late maturity, long life spans, and low natural mortality. Biological characteristics: Forty-six fish species were recorded from the exploratory fishing operations (Fisheries Agency of Japan 2008 Appendix A), but none of these species are endemic to the Emperor Seamounts nor listed as vulnerable or endangered on the IUCN Red List. Hart and Pearson (2011) analyzed fish species recorded from the Emperor Seamounts and found that 41 out of 49 fish species were also recorded elsewhere in the Pacific Ocean. Some precious corals were harvested from the 1960s to the 1980s; however, the initial abundance of precious corals is unknown. The interim measures to protect the cold-water corals were introduced in 2006 in the Emperor Seamount/Northern Hawaiian Ridge area. Gorgonaceans (8 families, 24 genera), Alcyonaceans (6 families, 7 genera), Antipatharians (4 families, 5 genera) and Scleractinians (6 families, 16 genera) have been observed in Japanese scientific surveys in the Emperor Seamounts/Northern Hawaiian Ridge area. No endemic coral species have been identified. Although the prediction of habitat suitability models for some cold-water corals indicated higher probability of occurrence compared to the surrounding deep sea floor (e.g., Davies and Guinotte 2011), results of the actual sea floor observation with underwater cameras revealed that distribution of cold-water corals was sporadic and sparse both inside and outside the traditional fishing grounds (Yanagimoto et al. 2008), indicating relatively low density and diversity of corals in the area compared to adjacent Aleutinan Islands or other Pacific seamounts (Etnoyer and Morgan 2005, Heifetz et al. 2005, Stone and Shotwell 2007). Besides cold-water corals, some literature information is available for benthic crustaceans (Sakai 1978) and foraminiferans (Ohkushi and Natori 2001). No marine teleost species, deep-water shark species or cold-water coral species found on these seamounts in this area so far are listed as the vulnerable or endangered species on the IUCN Red List. The relatively low diversity and endemism of fish and coral fauna observed in this area is in line with the recent views that seamounts are generally not isolated habitats with a highly endemic diverse fauna (Samadi et al. 2006, O’Hara 2007, Clark et al. 2012). Source of scientific data: Underwater camera survey and dredge sampling have been conducted to collect scientific information on species composition, distribution and abundance of benthic organisms on some seamounts in the area. Scientific observers onboard commercial fishing vessels collect data on fish species and incidental catch of benthic organisms. These scientific data, together with commercial catch and effort statistics, are reported to the Scientific Working Group of the NPFC for rigorous scientific review.
Current fishery management: Many of the seamounts in the Emperor Seamounts/Northern Hawaiian Ridge area have been utilized by commercial bottom fisheries since 1967. Currently, bottom fisheries in the area are managed by interim conservation measures of the NPFC, which require fishing participants of the NPFC (i) to limit fishing effort to the existing level, (ii) not to allow bottom fisheries to expand into new areas (in particular, north of 45°N), (iii) to assess the impact of bottom fisheries on marine species or any vulnerable marine ecosystem (VME), and (iv) to cease bottom-fishing operations and move 5 miles away from the location where a fishing vessel encounters cold-water corals. Japan and Republic of Korea have introduced additional voluntary measures as below: Japan Limit the number and capacity of bottom-fishing vessels at current level Limit fishing effort at 80% of the 1996-2006 level No fishing operation north of 45°N No fishing operation on sea floor deeper than 1500m Equipment of each fishing vessel with vessel monitoring system Deployment of onboard scientific observers on each fishing vessel Temporary closure of fishing season in November and December Temporary closure of the C-H Seamount Temporary closure of southeastern part of the Koko Seamount Republic of Korea Limit the number of bottom-fishing vessels at current level Equip each fishing vessel with a vessel monitoring system Deployment of onboard scientific observers on each fishing vessel Scientific surveys of fish species, and benthic habitat and fauna have been conducted by some participants of the NPFC. Results of these activities are reported to the Scientific Working Group of the NPFC.
Boehlert GW. 1988. Current-topography interactions at mid-ocean seamounts and the impact on pelagic ecosystems. GeoJournal 16: 45-52. Clark MR, Schlacher TA, Rowden AA, Stocks KI, Consalvey M. 2012. Science priorities for seamounts: research links to conservation and management. Plos One 7(1): e29232. Davies AJ, Guinotte JM. 2011. Global habitat suitability for frame-work forming cold-water corals. Plos One 6(4): e18483. Etnoyer P, Morgan L. 2005. Habitat-forming deep sea corals in the Northeast Pacific Ocean. In Freiwald A, Roberts JM (eds), Cold-water Corals and Ecosystems. Springer-Verlag, Berlin. pp.331-343. Fisheries Agency of Japan 2008. Appendix A. List of fishes collected by the Meisyo Maru #128 in 1993, expressed in relative abundance in weight by seamount depth zone, with related information. 1p. (http://nwpbfo.nomaki.jp/JPN-AppendixA.pdf). Fisheries Agency of Japan 2008. Appendix D. Information describing splendid alfonsin (Beryx splendens) fisheries relating to the North Western Pacific Regional Fishery Management Organisation. 22pp. (http://nwpbfo.nomaki.jp/JPN-AppendixD.pdf) Fisheries Agency of Japan 2008. Appendix E. Information describing the North Pacific armorhead (Pseudopentaceros wheeleri) fisheries relating to the North Western Pacific Regional Fishery Management Organisation. 20pp. (http://nwpbfo.nomaki.jp/JPN-AppendixE.pdf) Hart PJB, Pearson E. 2011. An application of the theory of island biogeography to fish speciation on seamounts. Mar Ecol Prog Ser 430: 281-288. Heifetz J, Wing BL, Stone RP, Malecha PW, Courtney DL. 2005. Corals of the Aleutian Islands. Fish Oceanogr 14: 131-138. O’Hara TD. Seamounts: centres of endemism or species richness for ophiuroids? Global Ecol Biogeogr 16: 720-732. Ohkushi K, Natori H. 2001. Living Benthic Foraminifera of the Hess Rise and Suiko Seamount, Central North Pacific. Deep-Sea Research Part I 48: 1309-132. Sakai T. 1978. Decapod crustacea from the Emperor Seamount Chain. Research on Crustacea 8 (Suppl): 1-40. Samadi S, Bottan L, Macpherson E, De Forges BR, Boisselier M-C. 2006. Seamount endemism questioned by the geographic distribution and population genetic structure of marine invertebrates. Marine Biol: 149: 1463-1475. Sharp WD, Clague DA. 2006. 50-Ma Initiation of Hawaiian-Emperor Bend Records Major Change in Pacific Plate Motion. Science 313: 1281-1284. Smoot NC. 1985. Guyot and seamount morphology and tectonics of the Hawaiian-Emperor elbow by multi-beam sonar. Mar Geol 64: 203-215. Smoot NC. 1986. Bathymetric atlas of North Pacific Guyots. A thesis submitted to the Graduate School of the University of Southern Mississippi. pp.129. Smoot NC. 1991. North Pacific Guyots. US Naval Oceanographic Office Technical Note TN 001-91. pp.93. Stock JM. 2006. The Hawaiian-Emperor Bend: Older Than Expected. Science 313: 1250-1251. Stone RP, Shotwell SK. 2007. State of deep coral ecosystems in the Alaska Region: Gulf of Alaska, Bering Sea and the Aleutian Islands.The State of Deep Coral Ecosystems of the United States. NOAA Technical Memorandum CRCP-3, Silver Spring, Maryland (2007): 65-108. Wilson JT. 1963. A possible origin of the Hawaiian Islands. Can J Physics 41: 863-870. Yanagimoto T, Takao Y, Abe K. 2008. Distribution of four orders of corals observed by ROV survey. 20pp. (http://nwpbfo.nomaki.jp/JPN-AppendixE.pdf) Yasui M. 1986. Albacore, Thunnus Alalunga, pole-and-line fishery around the Emperor Seamounts. NOAA Technical Report NMFS. 43: 37–40.
Areas described as meeting EBSA criteria that were considered by the Conference of the Parties
C1: Uniqueness or rarity Medium
Seamounts have unique geographical features and provide habitat for a variety of benthic species. However, most of the species of demersal fish and benthic organisms recorded in this area are common to other areas in the Indo-Pacific, and no endemic species has been recorded on these seamounts.
C2: Special importance for life-history stages of species Medium
North Pacific armorhead, Pseudopentaceros wheeleri, uses southern seamounts of this area as adult habitat and spawning ground while larvae and juveniles are widely distributed in the epipelagic zone of the North Pacific Ocean. Some pelagic species also utilize the water column over the seamounts in the area for feeding or migration.
C3: Importance for threatened, endangered or declining species and/or habitats Low
No marine teleost species, deep-water shark species or cold-water coral species found in these seamounts are listed as vulnerable or endangered species in the IUCN Red List. A few sparse colonies of precious coral were reported, but no dense aggregation has been reported.
C4: Vulnerability, fragility, sensitivity, or slow recovery Medium
Some precious corals were harvested from the 1960s to 1980s; however, the initial abundance of precious corals is unknown. The interim measures to protect the cold-water corals were introduced in 2006 in the Emperor Seamount Chain. The prediction of habitat suitability model of some cold-water corals indicated higher probability of occurrence compared to the surrounding deep-sea floor, but actual results of the underwater observation indicated that distribution of corals was sporadic and sparse in most cases.
C5: Biological productivity Medium
The biological productivity of these seamounts is higher than that of the neighbouring deep-sea floor, but is relatively lower than that of other productive seamounts located in northern North Pacific Ocean.
C6: Biological diversity Medium
The species compositions of deep-sea corals showed low species diversity, but 46 fish species were reported in the exploratory fisheries in the area.
C7: Naturalness Low
Most of the seamounts in the area have been fully utilized by commercial fisheries since the 1970s, and currently managed by interim conservation measures of the NPFC. Therefore the naturalness of these seamounts is low.