Groundfish Fisheries and Research in the Vicinity of Seamounts in the North Pacific Ocean RICHARD N. UCHIDA and DARRYL T. TAGAMI Introduction been dredged from their summits. By mount-groundfish resources. definition, a seamount is an elevation In October 1976, just 5 months before In the central and western North that rises 1,000 m or more from the sea enactment of the Magnuson Fishery Pacific Ocean, one of the chief topo­ floor and is flat and of limited extent Conservation and Management Act graphic characteristics of the ocean across the summit (U.S. Board on Geo­ (MFCMA), the Honolulu Laboratory of floor is the large submarine volcanoes, graphic Names, 1969). the Southwest Fisheries Center which were once high islands. Some of The Hawaiian Archipelago and the (SWFC), National Marine Fisheries these former volcanic islands are now numerous seamounts to the north and Service (NMFS), launched an investiga­ worn down into low, sandy atolls such northwest of the chain are shown in Fig­ tion of the marine resources of the as Kure Atoll in the Hawaiian Archi­ ure I. Those to the north are the Musi­ NWHI. Because the extent of the inves­ pelago (Menard and Hamilton, 1963; cians Seamounts which have summits tigation was beyond the capabilities of Carlquist, 1970). However, many oth­ that are rather deep, most of them well the staff and facilities of any single re­ ers have subsided 0.5 km or more be­ over 1,650 m below the sea surface. The search agency in Hawaii, the SWFC low the sea surface and their summits seamounts discussed in this report lie on proposed a cooperative effort with the lack a coral cap. These are the guyots the Hawaiian and Emperor Seamount Hawaii Division of Aquatic Resources or seamounts identifiable as former Ridges. The Hawaiian Ridge extends for (HDAR), Hawaii Department of Land islands by their form and by the pres­ some 1,350 n.mi. from the Island of and Natural Resources, and the U.S. ence of shallow-water fossils that have Hawaii on the southeastern extremity to Fish and Wildlife Service (USFWS). Kure Atoll on its northwestern end. The From the proposal evolved a formal Emperor Seamount Ridge then con­ tripartite agreement which, in effect, tinues in a northerly direction and ter­ gave responsibility to the HDAR for the minates at the juncture of the Aleutian survey and assessment of the inshore and Kurile Islands arc and trench sys­ fishery resources and to the USFWS for ABSTRACT-The trawl fishery over the tems (Malahoff and Woollard, 1970). land-associated resources such as sea central North Pacific seamounts expanded rapidly after 1967 when exploratory fishing The 200-mile Fishery Conservation and land birds. The SWFC assumed re­ by Soviet trawlers demonstrated commer­ Zone (FCZ) around the Hawaiian Ar­ sponsibility for developing a quantita­ cial concentrations ofpelagic armorhead, chipelago includes the Northwestern tive fishery survey and assessment ofthe Pentaceros richardsoni, and smaller quan­ Hawaiian Islands (NWHI), a chain of slope, coastal pelagic, and seamount re­ tities ofalfonsin, Beryx splendens. In 1969, Japanese trawlers entered the fishery but small islands stretching from Nihoa to sources. A short time after the agree­ developmental problems led to wide catch Kure Atoll. Surrounding these islands ment was signed, a fourth agency, the fluctuations in 1969-71. After 1971, catches are numerous submerged banks and University of Hawaii Sea Grant College stabilized and then peaked at 34,538 metric seamounts, including Hancock Sea­ Program, became an active participant tons in 1974. mounts, which in recent years have been Hancock Seamounts, within the 200-mile in the investigation by assuming respon­ U.S. Fishery Conservation Zone around the fished by Japanese trawlers under a sibility for research to fill obvious gaps Hawaiian Archipelago, were fished in quota established by the preliminary in the tripartite investigation. 1972-76 by Japanese trawlers, producing management plan (PMP) 1 for sea- This report reviews the historical de- annual catches from 653 to 8,518 metric tons. In 1978-81, U.S. observers accom­ panied three Japanese trawlers which made Richard N. Uchida and Darryl T. Tagami are six trips to Hancock Seamounts. Observer 'Southwest Region, National Marine Fisheries with the Honolulu Laboratory, Southwest data indicated that the pelagic armorhead Service, NOAA, Terminal Island, California. Fisheries Center, National Marine Fisheries Final environmental impact statement/ Service, NOAA, P.O. Box 3830, Honolulu, HI stock had recovered to some extent from the Preliminary fishery management plan. Sea­ 96812. Mention of trade names or commercial intense fishing prior to 1977. The catch per mount groundfish fishery resources (pelagic ar­ firms in this paper does not imply endorsement unit ofeffort in 1980 and 1981 improved and morheads and alfonsins). NOAA, NMFS, by the National Marine Fisheries Service, showed an upward trend. January 1977, 27 p. NOAA. 46(2) 1 1"\ ~ ··.·.·JlOgu Smt ';). 'Ojin Smt. ~ ~ A q. <~ r-"""",:·,."-Ki!!.!.mm"",,ei-4S~m!.C.t.--t_~ --+ ~t- +- + ----+------35° Mellish Bank ';~ ~ Berlin Smt. ~ ,Lange Smt. Rossini Smt - > 'Yuryaku Smt. I Kern Smt.! ?-:t Donizetti Smt MsILMWrA.GURKEOEup' '. Kammu Smt. ~. V Mahler Smt. ""-". Shuberf Smt. Calahan Smt. .' 3/ ----- ~ G dd Sm . )i7::::"'II~ Smt.. 12 a ard t. C'-s- Brahms Smt. :.. Honc,ock Smt. _ ._. ," :.c;'~ Dvorak Smt. r------f----,L:.:.'---rc'--------+-----"__----i------.-i--·--.:....--.:..._--'D!!.eb~u~ss'r.y~Sm~t':.... ) .. Smt 1\:"Smt 10 ~ RaChmaninrff smt.r~~:;k~~~Y Smt. 30 .~- ..,.•.•. :~ure). .. Ladd Smt. ~ogonln.l Smt.· Mozart Smt. s\mt.15~l Nero Smt.., . '"..Mldway I. PearlI a Hermes H4I 1Y4114tv . Reef I RID G"eg Smt. I Gf: Ravel Smf.· . '. Handel Smt. -. Salmon Bonk ~: .smt.9 ~Ho~~nSmt':GI~·ckSmt. 1 S,~t. 8 . Valadar Smt. lisianski I',':' . Pioneer Smt. I Chopin Smt. : . I.'·c·" • Layson 1.1 ROIfo Bonk ~ Prokofiev Smt. ""'"'--- Northampton Smt ~".~Moro~eef • Gardner Pinnacles Mendelssohn Sm~ 250 St R09aheh Bank ~ -- Brooks Bonks ~ Paul Smt Fr Frigate· I • Necker I ~ Shools .. Nihoo I. ~~ /Necker Choutouguo OKouai TU§~t'.OOO , Ridge Smt. ?'Niihou Oahu WiSConSin Smt. <:s: ~oloka i Tlru Smt LanaiO~Maui I----t-----+----+---~-+I J. \ Ha~ii0 0 175 E 1800 175 0 1700 Iq5° "'" I 0 0 W V- Figure I.-Hawaiian Archipelago and nearby seamount chains and groups. velopment of the seamount-groundfish tral North Pacific has been described in Kimmei Seamount, the Milwaukee trawl fishery over the central North detail by Chikuni (1970, 197Ib), Sakiura Seamount group, and Hancock Sea­ Pacific seamounts, presents an analysis (1972), Sasaki (1974), and Takahashi and mounts (Sakiura, 1972). of the data collected by U.S. observers Sasaki (1977). Until 1967, the seamounts The initial catches ofthe Soviet trawl­ on Japanese trawlers fishing over Han­ aroused very little interest because most ers were impressive: As much as 20-30 cock Seamounts in 1978-81, and de­ fishery s:::ientists were unaware of the metric tons (t) were taken in hauls of scribes the results of the SWFC's sur­ resources associated with them. 10-20 minutes (Sakiura, 1972). The veys over the seamounts within the FCZ The U.S.S.R. was the first nation to catch rate averaged 5.8 t per half-hour around the Hawaiian Archipelago. An commercial'ly exploit the seamount­ tow in 1968 and doubled to 11.7 t per earlier report described the exploratory groundfish resources in this area. In half-hour tow in 1969. Furthermore, in survey at Hancock Seamounts from Oc­ November 1967 a Soviet commercial one 8-month period from December tober 1976 through May 1979 (Gooding, trawler discovered large concentrations 1969 to July 1970, Soviet trawlers re­ 1980). of pelagic armorhead, Pentaceros portedly harvested 133,400 t of pelagic richardsoni, on the Emperor Seamount armorhead from the seamounts. A sec­ Description of the Fishery Chain which led to an almost immediate ond species of commercial value, the History exploitation ofthe resource by the Soviet alfonsin, Beryx splendens, made up as trawling fleet and prompted further much as 30 percent of some of the trawl The historical development of the exploratory fishing on seamounts closer hauls. The Soviet trawlers reported that seamount-groundfish fishery in the cen- to the Hawaiian Archipelago including the thickness of the schools of pelagic 2 Marine Fisheries Review armorhead over the seamounts was as continued into 1977, but landings re­ cock in 1978-81 after the enactment of much as 160 m but usually was closer to mained low (NMFS, 1977). the MFCMA. 30 m. The size of the catches reported Because Hancock Seamounts fall Historical Japanese Catches by the Soviets, however, was ques­ within the U.S. FCZ, it is of interest to tioned by Sakiura (1972). Because the early years (1969-71) of compare the catch and trawling effort In August 1969, Japanese trawlers of the Japanese seamount-groundfish trawl over them with the total central North 1,500-4,000 gross tons entered the fishery were exploratory and devel­ Pacific catch and effort. The Japanese fishery. Their initial effort was mostly opmental, annual catches fl uctuated commercial trawling effort at Hancock exploratory, but they set the stage for widely; 1972 is regarded as the real be­ Seamounts in 1972-76 varied from 24 to full-scale commercial operations by ginning of the commercial fishery. 212 hours and averaged 74.6 hours 1972. Frequently, some trawling was The annual catch, trawling effort, and (Takahashi and Sasaki, 1977). Hancock conducted by Japanese trawlers en route catch per unit of effort (CPUE) of Seamounts received from < I to 29 per­ to and from the Bering Sea and the Gulf pelagic armorhead for all the major sea­ cent of the entire central North Pacific of Alaska. To assist in the development mounts fished by the Japanese in 1969­ trawling effort.