Initial Discoveries of Fish Faunas on Seamounts and Offshore Banks in the Eastern Pacific!

CARL 1. H UBBS2

THE RECENT DISCOVERY in the Pacific Ocean available on or over these isolated rises to of numerous submerged mountains (Hess, yield profitable fisheries? 1946; Menard and Dietz , 1951; Menard, What factors, physico-chemical or biotic, 1955, and in press), including "banks" (rising are responsible for the abundance of life on to a depth of less than 100 fathoms) as well and over these rises? The first thought that as the flat-topped "guyots" and other "sea­ comes to mind is that the elevations in the mounts" (with minimum depths greater than bottom contour induce disturbances in the 100 fathoms ), has posed intriguing questions deep currents, which no doubt have greater regarding their faunas. Some of these ques­ velocities than they were long thought to tions are: have, and that such disturbances induce up­ What species inhabit the individual banks welling and the enrichment of the upper and seamounts, and in what regularity and waters. abundance? Systematic explorations of the faunas on How did these species become dispersed to the isolated banks and seamounts (and oce­ and established on these structures? anic islands) should yield rich returns , both What bearing may the determined consti­ scientifically and commercially. As yet only tution of these isolated faunas have on our fragmentary information has been accumu­ ideas concerning past and present oceanic lated. Some such fragments of data, recently circulation and temperatures? acquired, concernin g the fish faunas on sea­ Do the banks and seamounts (as well as the mounts and banks from the Gulf of Alaska islands) provide stepping stones for the to far-off Chile, are presented here. transgression of narrow to broad oceanic Embassichthys bathybius (Gilbert) on areas, even the supposedly vast eastern Pa­ Pratt Seamount cific barrier that separates the Indo-Pacific and American faunas (Ekman, 1953: 21, 72, 292)? On August 22, 1951, an adult "deepsea May some elements in the faunas of the sole" 242 mm . in standard length surprisingly deeper seamounts be relicts that have become was caught in a rock dredge being hauled at adapted to increasing depths as the seamounts a depth of 510 fathoms on the side slope of have subsided (or become flooded)? If so, Pratt Seamount in the Gulf of Alaska, at Lat. the faunistic evidence may have some bearing 560 20' N ., Long. 1420 30' W., about 210 on the historical interpretation of the sea­ nautical miles offshore. It was obtained by mounts. Henry W. Menard and John D. Isaacs on the To what degree has isolation on the banks research ship "Horizon," on the Northern and seamounts led to speciation? Holiday Expedition of the Scripps Institution Are either demersal or pelagic fishes (or of Oceanography (Dredge No.5; Collection other animals) sufficiently abundant and SIO 53-187). This record constitutes a notable north­ 1 Contributions from rhe Scripps Insr irurion of O ceanography. Manu scripr received April 10, 1958. ward as well as seaward extension ofthe range 2 Un iversity of Californ ia, La J olla. of this deep-water pleuronectid. Long known

311 312 PACIFIC SCIENCE, Vol. XIII, October, 1959

only from off southern California, recently it thought to be a specimen of this species as has been reported from off northern Cali­ S. babcocki, new species. fornia (Hagerman, 1950) and from off Wash ­ Welander and Alverson mentioned that the ington (Welander and Alverson, 1954: 42-43). type of S. bilineatus was one of 30 fish speci­ Unpublished records show that this com­ mens " caught by personnel of the U . W. mercially utilizable fish is not uncommon in oceanography vessel Brown Bear in the vicin­ deep waters off northern California and Wash ­ ity of Cobb Seamount on August 7, 1953." ington. It is becoming of minor importance It is to be hoped that complete lists of species in the trawl fishery, as operations are being taken on or about each seamount will be extended into deeper water. Its occurrence on published. at least one seamount suggests the possibility Perhaps fisheries may develop on the sea­ that the trawling grounds may eventually be mounts for rockfishes (Sebastodes spp. ), as extended far seaward, where depths are well as for the halibut, Hippoglossus stenolepis appropriate. Schmidt, and other flatfishes. I have underway a distributional and vari­ SHORE AND PELAGIC FISHES ON BANKS AND ational study of this poorly-known flounder. SEAMOUNTS OFF CENTRAL CALIFORNIA Sebastodes ruberrimus Cramer and Other A number of coastal and pelagic fishes of Fishes on Cobb Seamount expectable species were recorded by Follett A rockfish caught on Cobb Seamount, (1952) from several banks and seamounts off about 280 nautical miles off Washington and the central California coast, at no very great about 240 miles southwest of Vancouver Is­ distance offshore. This is not to mean, how­ land, at Lat. 46° 44' N., Long. 130° 47'W ., ever, that high interest and potential impor­ was described by Welander and Alverson tance is not to be attached to such inshore (1954: 37-40, figs. 1, 2) as representing a new rises. species, Sebastodes bilineatus. By examining T UNAS AND TUNA FORAGE FISHES FROM this specimen (No. 10099, University of " ST RANGER BANK" ("HURRICANE BANK") Washington Fish Collection) in detail on June 11,1956, I verified the belief ofJulius B. In 1957, on an expedition from Scripps Phillips, W. I. Follett, and myself that it is a Institu tion of Oceanography, on the research specimen of the large S. ruberrimus, in the ship "Stranger," Adrian F. Richards discov ­ striped, juvenile stage. The contrast between ered, at Lat. 16° 52' N ., Long. 117° 30' W., the dark ground color and the light stripes is roughl y 200 nautical miles southwest of unusually bold, but since color intensity Clarion Island, a shallow bank rising from varies so greatly in fishes and since all other oceanic depths to a depth of approximately characters observed fall within the observed 15 fathoms. This bank was assigned the tenta­ range of variation of S. ruberrimus, it seems tive name Stranget Bank by the discoverer. doubtful that the species is modified on Cobb Tuna fishermen of San Diego, who dub the Seamount. Slight differentiation, however, is structure "Hurricane Bank, " from the heavy a remote possibility. Data on the type of S. weather often encountered there , promptly bilineatus will be included in a forthcoming began fishing there and in less than a year had contribution by Hubbs and Follett. taken from the newly found fishing ground Thompson (1915: 121) observed that S. well over 1,000 tons of yellowfin tuna, N eo­ ruberrimus is "the most abundant of all spe­ tbannus macropterus (Temminck and Schlegel), cies of the genus on the halibut banks," but and smaller quantities ofskipjack tuna, Katsu­ in the same paper described what is now wonuspelamis (Linnaeus). At the time of writ- Seamounts and Offshore Banks- HUBBS 313

ing it is evident that within the first full year of flying fish of undetermined speCIes also the catch will definitely exceed 2,000 tons, occur in the tuna stomachs. with a value to the fishermen of more than A thorough study of the fish fauna of one-half million dollars; and the relative Stranger Bank is much to be desired, espe­ proximity of the ground represents a great cially in view of the thorough analysis of the saving in expenses. Tuna fishermen have re­ Revillagigedo fish fauna being conducted by ported taking some rainbow runners , Elegatis Boyd W. Walker and associates. bipinnulatus (Quoy and Gaimard ), from this For information and material on the fishes same bank. and fisheries of this bank I am indebted to During the Island Current Survey of May­ Bell M . Shimada and Franklin G . Alverson of June, 1958, personnel of the Inter-American the Inter-American Tropical Tuna Commis­ Tropical Tuna Commission caught about the sion and to Wilbert M . Chapman of the bank a number of young yellowfin tuna. On American Tunaboat Association . June 1 an adult male of the labrid Bodianus Pterygotrigla picta (Gu nther) on a Guyot diplotaenius (Gill) was caught on the shoalest far off Chile part of the bank (it was identified from a kodachrome). Many sharks, includ ing some On January 26, 1958, a triglid fish (gurnard hammerheads, Sphyrna sp., were seen, to con­ or sea robin ) of considerable zoogeographical firm the reports that sharks abound here. On interest was captured incidentally in a rock J une 5 one wahoo, A canthocybium solandri dredge being hauled at a depth of129 fathom s Cuvier, was caugh t, and several mantas, pre­ on a guyot rising from an extensive ridge in sumably M anta hamiltoni (Newman), were the southeastern Pacific. It was preserved by seen. Robert H . Parker on the research ship Further information on other fishes that " Spencer F. Baird" of Scripps Institution of live over and about this bank comes from an Oceanography, on the I. G. Y. Downwind initial examinati on of stomach contents of Expedition (Station 73; SIO 58-42). This un­ yellowfin tuna, collected there for the Inter­ named guyot is at Lat. 25° 44' S., Long. American Tropical Tuna Commission and 85° 25' W., which is about 800 miles off the now being analyzed by the staff of the Com­ Chilean coast, abou t 300 miles westerly from mission . Young to half-grown specimens of Isla San Felix, and nearly 600 miles northwest the spiny trun kfish, Lactoria diaphana (Bloch of Isla Juan Fernandez. It is in a region where and Schneider), constitute a notably high seamounts appear to be numerous, and is on proportion of the food . Some stomachs are a submarine ridge that seems to extend west­ filled with this bony creature, which else­ ward at least to Easter Island (Fisher, 1958: where has been found to be eaten by this 20-25, figs. 1, 8, 9). tuna. This trunkfish ranges very widely Although the specimen is youn g (54 mm. through trop ical regions, and even, on oc­ in standard length ) and was badly crushed casions , as far northward as California. A posteriorly in the rock dredge, it seems identi­ sample (SIO 58-56) from the stomach of a fiable as Pterygotrigla picta (Gunther). This tuna caught on this bank comprises 487 speci­ species was originally very briefly described , mens of this trunkfish, 13 to 44 mm . in stand ­ but magnificently figured, by Gunther (1880: ard length. Another lot (SIO 58-57) comprises 24-25, pl. 13, fig. A), as Trigla picta, on the 7 specimens, of similar size. One tuna con ­ basis of a 1O.5-inch specimen collected by the tained a large youn g triggerfish (SIO 58-54) "Challenger" on Isla Juan Fernandez , far off of the common, wide-ranging, more or less the coast of Chile. The species has been re­ pelagic species X anthichthys Iineopunctatus(Hol­ ported also from New Zealand and Australia lard) ; its standard length is 52 mm . Remains (McCulloch, 1929: 393), but not from the 314 PACIFIC SCIENCE, Vol. XIII, October, 1959

American mainland. This distributional pat­ for a light border; the other fins are almost tern seems to be related to the bottom to­ wholly clear. In coloration the young speci­ pography within the south temperate zone men corresponds better with the figure given of the Pacific: there is a very deep trench off by Mann (1954: 309) for the " pez mariposa the Chilean coast, but from the vicinity of de Juan Fernandez," which he designated islas Juan Fernandez and San Felix westward Chelidoniehthys pietus. numerous submarine ridges and peaks rise to Trigla pieta has been referred, properly I various heights below and above sea level. It think, to the genus Pterygotrigla Waite (1899: may be predicted that the species will be 108), which was based on the Australian spe­ found not only on the guyot nearly 600 miles cies Trigla polyommata Richardson. Although northwest of Juan Fernandez, but also on quite different in coloration, P. pieta and P. other rises between the offshore islands of polyommata seem very similar in structure. Chile and New Zealand. It is not known The genus Pterygotrigla has been attributed whether seamounts intervene between Juan to Japan (Matsubara and Hiyama, 1932: 8-14, Fernandez and San Felix, and it is now figs. 2-5), but the Japanese species referred to doubted that <, the long charted intervening the genus differ trenchantly from P. pieta and ridge exists. P. polyommata in lacking vomerine teeth. This young specimen differs in a number They are also said to have a " distinct anal of respects from the characters indicated in spine" (a hardened soft-ray?), which does not the original description and figure of Trigla seem to be true of the Southern Hemisphere pieta, but these differences seem attributable species. Though the two groups agree in to age and individual variation. The dorsal many characters it seems advisable to put spines number VIII instead of VII, but the them in separate genera. The name Otobime eighth is short and very slender (and is per­ Jordan and Starks (1907) is available for the haps concealed in the type ); the number of common Japanese species bemisticta (the dorsal soft rays (12) agrees. The anal rays are type species), and probably for Pterygotrigla 11, not 12, but some variation is expected. ryukyuensis Matsubara and Hiyama. (The principal caudal rays number 6 + 5 = Otobime differs further from Pterygotrigla in 11, and each pectoral has 15 rays, in the the small size of the dorsal bucklers. The formula i, 9, ii + 3.) The nuchal spine is distinction in the first anal ray may not be much longer, reaching to below the base of valid, for a young specimen of Otobime bemi­ the third dorsal spine (probably as a function stieta has this ray paired, articulated, and of youth), and is about as long as the humeral flexible. spine. (The pectoral fin, as in the type, reaches It seems clear from the original account to about the seventh anal ray.) The preopercu­ that Trigla guttata, which was described with­ lar spine (at the end of the cheek ridges ) is out comparisons by Philippi (1896: 375­ double, rather than single, but the lower point 376) from Juan Fernandez, is a synonym of is definitely the smaller, and it probably be­ Pterygotrigla pieta (Giinther)- as was assumed comes obsolete in larger fish. The body is by McCulloch (1929: 393). But the gurnard similarly marked with light-ringed blackish from Islas Juan Fernandez that was figured spots, but these spots (as expected) are fewer. and discussed by Mann (1954: 309) as Trigla On the head the spots are discernible, though punetata Philippi obviously belongs in a very faint, as though just developing. The fins, different species . From the figure it seems unlike those on the type, are unspotted: in clearly referable to Chelidoniehthys, as defined the spinous dorsal the membranes are sooty by Matsubara and Hiyama (1932: 4). It even outward; the second dorsal has a submarginal seems probable that the specimen may be re­ dark band; the pectoral is very dark, except ferred to C. kumu (Lesson and Garnot), an Seamounts and Offshore Banks- HUBBS 315

important species that is accorded a range may be attached to a study of the faunas of from New Zealand and Australia to Japan the many banks and seamounts that rise (see Matsubara and Hiyama, 1932: 5- 7, fig. toward the surface from the depths of the 1). Like Pterygotrigla, Chelidoniehthys is un­ Pacific Ocean. Many and perhaps most of known in Chile. Its occurrence on Juan Fer­ these structures seem capped and surrounded nandez parallels that of Pterygotrigla pieta, and by productive water. The spectacular take of it may be predicted that Chelidoniehthys will be tuna on the Stranger, or Hurricane, Bank has found on seamounts, banks, or islands be­ been mentioned. Milner B. Schaefer, director tween Juan Fernandez and New Zealand. of research for the Inter-American Tropical Both Pterygotrigla and Chelidoniehthys belong Tuna Commission, has assured me that good to a distributional category that may be classi­ catches have been made about other banks fied as antitropical Indo-Pacific, and contrast and even about seamounts that nowhere sharply with the American triglids (Prionotus closely approach the surface. Henry W. and the derived Bellator). Comparison of a Menard of the Institute of Marine Resources, specimen of P.pieta from Isla J uan Fernandez University of California, leading student of (an adult 340 mm. in standard length collected seamou nts, tells me that he has obtained by the Mellon Expedition in Bahia Cumber­ strong field indications, from echograms, that land on February 28, 1936) with specimens large objects (presumably fish or giant squid ) of Chelidoniehthys kumu from Japan discloses form a halo around and far above many sea­ many differences. The row of keeled scales mounts between California and Hawaii . It along the entire dorsal base is replaced by seems highly probable, as is stated in the in­ greatly enlarged flat bucklers along the base troduction, that the submarine mountains, of the spinous dorsal only. P. pieta differs even those that are isolated and deep, disturb further from C. kumu in a feature of the the currents sufficiently to induce extensive lateral line, which ends simply, immediately upwelling. beyond the caudal base, instead of being The benthic faunas of the banks and sea­ forked and continued as two or three lines mounts do not give promise of such com­ across the caudal fin. The head is much larger, mercial potential, but may prove of greater and the body is much more contracted ' at scientific interest, particularly in respect to the base of the caudal fin, which is sharply zoogeography and speciation. forked rather than merely emarginate. The orbital rim is spineless, but the opercular; REFEREN CES nuchal, and humeral spines are greatly en­ larged. The nape, in advance of the greatly EKMAN, SVEN. 1953. Zoogeography ofthe Sea . enlarged buckler surrounding the first dorsal xiv + 417 pp., 121 figs. Sidgwick and spine, is scaleless rather than scaly. The teeth Jackson, Ltd., London. are almost shagreenlike; those of the lower FISHER, R. 1. (Editor). 1958. Preliminary re­ jaw are deflected outward over the anterior port on Expedition Downwind, University edge of the lower lip. The vomerine teeth are of California, Scripps Institution of Ocean ­ in an oval rather than a broadly V-shaped ography IGY Cruise to the southeast patch . Most of these differences show in the Pacific. IGY World Data Center A, Nation­ figures reprod uced by McCulloch (1922: 119, al Academy of Sciences, IGY General pI. 39). Repor t Series Number 2: i-iii, 1-58, figs. NEED FOR FURTHER STUDIES 1-21. FOLLETT, W. I. 1952. Annotated list of fishes These brief notes tend to show that great collected by the California Academy of scientific as well as commercial importance Sciences during six cruises of the U.S. S. 316 PACIFIC SCIENCE, Vol. Xlll, October, 1959

"Mulberry" conducted by the United the fish and fishlike animals of New South States Navy off central California in 1949 Wales. Part iii. A ust. Zool. 2, pt. 3: 86-130, and 1950. Proc. Calif A cad. Sci. 27: 399­ pls , 25-43. 432, pls , 21-26. MCCULLOCH, ALLAN R. 1929. A check-list of GUNTHER, ALBERT . 1880. Report on the the fishes recorded from Australia. M em. shore fishes procured during the voyage of Aust. Mus. 5, pt. 3: 329- 436. H. M . S. " Challenger" in the years 1873­ MENARD, HENRY W. 1955. Deformation of 1876. IN The Voyage of H. M. S. " Chal­ the northeastern Pacific basin and the West lenger," Zoology 1(6) : 1-82, pIs. 1-3 2. Coast of North America. Bull. Geol. Soc. HAGERMAN, FREDERICK B. 1950. The exten ­ Amer. 66: 1149-1198, figs. 1-30, pi. 1. sion of the range of the deep sea flounder, - -- In press. Submarine vulcanism in the Embassichthys bathybius (Gilbert) . Calif Fish Pacific Basin. Proc. 20th Int. Geol. Congo Game 36: 165-166, fig. 52. MENARD, HENRY W., and ROBERT S. DIETZ. HESS, H . H . 1946. Drowned ancient islands 1951. Submarine geology of the Gulf of of the Pacific Basin. Amer. J. Sci. 244: 772­ Alaska. Bull. Geol. Soc. A mer. 62: 1263­ 791, figs. 1- 8B. 1285, figs. 1-10, pls. 1-5. JORDAN, DAVID STARR, and EDWIN CHAPIN PHILIPPI , R. A. 1896. Peces nuevos de Chile. STARKS. 1907. Note on Otohime, a new An. Univ. Chile 93: 375-390. genus of gurnards. Proc. U. S. N at. M us. THOMPSON, WILLIAM F. 1915. A new fish of 32: 131-133, 1 fig. the genus Sebastodes from British Columbia, M ANN F., GUILLERMO. 1954. L a vida de los with notes on others . Rep. B. C. Comm. Fish. pecesen aquas chilenas. Ministerio de Agricul­ 1914: 120-122, 1 pi. rura [and] Universidad de Chile, Santiago de WAITE, EDGAR R. 1899. Scientific results of Chile. 342 pp ., man y figs. the trawling expedition of H . M . C. S. MATSUBARA (formerly Sakamoto), KIYO­ "Thetis." Fishes. M em. A mt. M us. 4: 25­ MATSU, and YOSIO HIYAMA. 1932. A review 128, figs. 3- 10, pls. 1- 30. of the Triglidae, a family of mail-cheeked WELANDER, ARTHUR D ., and DAYTON 1. fishes, found in the waters around Japan. ALVERSON. 1954. New and little kn own J. Fish. Inst. Tokyo 28: 3- 67, figs. 1- 22. fishes of the eastern Pacific. Fish. Res. Pap. M CCULLOCH, ALLAN R. 1922. Check list of Wash. Dept. Fish. 1(2): 37-44, figs. 1- 2.