JapaneseJapaneseSociety Society ofSystematicof Systematic Zoology Species Diversity, 2oo1, 6,133-164 FreshwaterFishes of the Kuril Islands and AdjacentRegions Theodore W. Pietsch', Kunio Amaoka2, Duane E. Stevensoni, Erin L. MacDonald', Brian K. Urbaini and Juan Andres L6pez3 i School oj`Aguatic and Ftsher:y Stiences, University of VP(ashington, Box 35510a Seattle Wicshington 98195510a USA E-mail: tuzp@u. washington.edu 2 Fticulty ofFisheries, HbhkaidO Vniversity, Htzkocinte, HOhkaicto, 041-8611 Japan 3 Department of Zoology and Genetics. fowa State Ulriiversity, Ames, fowa 50011-a22a USA (Received 19 May 2000; Accepted 15 Februarvy 2001) Fishes were collected in freshwater habitats during six consecutive sum- mers (1994-1999) on the 30 major islands of the Kuril Archipelago as part of a joint U.S., Russian, and Japanese biotic survey and inventory, which has come to be known as the international Kuril Island Project (IKIP). A total of 39,269 specimens, representing eight families, 12 genera, and 28 species (in- cluding two previously undescribed species, 11 new records for the Archipel- ago, and 33 new records for various islands), was analyzed in the context of published literature on the freshwater fish faunas of the Kuril Islands and adjacent regions, namely Kamchatka, Hokkaido, and Sakhalin. The geologic history of the Archipelago is reviewed in light of present-day fish distribu- tions. As expected, species diversity, as compared to that of Kamchatka and Hokkaido, fans off abruptly as one moves centrally from both the northern and southern ends of the Archipelago, the number of species dropping to zero on some of the central islands. It appears that differences in island size, and therefore available habitat, are the primary determinant of diversity, coupled with the secondary effects of former connections between land- masses and distance from adjacent source biotas. Key Words: Fishes, freshwater, geologic history, zoogeography, Kuril Is- lands, Hokkaido, Sakhalin, Kamchatka. Introduction In the current renewal of interest in global biodiversity, the complex and threatened fioras and faunas of tropical regions of the world have received consid- erable attention. In contrast, certain temperate and boreal biotas have been ig- nored, despite high biotic diversity, the absence of basic taxonomic miiormation, and the threat of plant and animal extinctions. Of all such northern regions, the is- "biologically lands of the Kuril Archipelago are among the most unknown" and, at the same time, in danger of over-exploitation (Stephan 1974). A chain of more than 56 islands, the system is only slightly smaller than the Hawaiian Islands, covering an area of 15,600km2 and providing 2,409km of coastline (Fig, 1). Stretching 1,2oo NII-Electronic Library Service JapaneseJapaneseSociety Society ofSystematicof Systematic Zoology 134 Theodore W. Pietsch et al. Fig, 1, The islands of the Kuril Archipelago. Note that the name Ushishir incorporates two very closely situated islands (almost touching each other at low tide), Yankicha and Rypon- "The kicha, @ Oxfbrd University Press 1974. Reprinted from Kuril Islands: Russo-Japanese Erontier in the Pacific" by John J. Stephan (1974), by permission of Oxford University Press. km between Hokkaido, the northernmost island of Japan, and the Russian penin- sula of Kamchatka (from 430 to 510N latitude), the Kurils divide the Sea of Okhotsk from the PacMc Ocean and form the northern extension of an insular arc that orig- inates in the Ryukyu and Mariana archipelagos to the south and continues as the Aleutian Islands to the north and east. All of the Kurils are volcanic in origin, ranging in age from Upper Cretaceous to Late Pleistocene (Table 1); each island has a unique geological and biological history. Substantial epportunities fbr in situ diversification are provided by great distances between the islands and mainland source biotas, and by significant barriers to plant and animal dispersal, such as deep channels between islands, associated with strong ocean currents. Very little has been published on the fauna of the Kuril Islands; general state- ments about the larger mammals, marine birds, and commercially important fishes (salmon and cod) and crustaceans (king crab) are the only exceptions. Brown bears, wolves, squirrels, and snowshoe hares inhabit the 1arger islands. Foxes brought from Japan to Yankicha (Ushishir) fbr commercial breeding are now abundant there. Reindeer are raised on Paramushir. Tens of thousands of sea otters, fur seals, and sea lions once populated the chain, but today only sma}1 colonies exist on the central islands (Stephan 1974; personal observations). The lit- erature records more than 170 species of birds, but some unpublished esttmates NII-Electronic Library Service JapaneseJapaneseSociety Society of Systematic Zoology Fishes of the Kuril Islands 135 are as high as 280 (V. A. Nechaev 1969, and personal communication, 14 May 1993). Island rivers seasonully have heavy runs of salmon, and offtshore waters support abundant populations of cod (Gadus macrocephalus Tilesius, 1810), mackerel (Scomber J'aponicus Houttuyn, 1782), and ocean perch (Sebastes spp,). King crab from Kunashir and Iturup are stil1 harvested in large quantities. Although the general outlines of the fiora and fauna of the Kurils can be sum- marized, more detailed information is nonexistent or unpublished; what little is published is confined to the Russian and, to a lesser extent, the Japanese scientific literature. Little systematic collecting has ever been done, and since the close of World War II, only a few Russian biologists have done any work of significance, With the exception of a few Russian collections (e.g., those of the various institutes ef the Russian Academy of Sciences at Vladivostok, Magadan, St. Petersburg, Moscow, Novosibirsk, and Yuzhno-Sakhalinsk), museum samples of plants and an- imals originating from the Kurils are unavailable and frozen tissues are com- pletely non-existent, The biota is a mix of Japanese, Kamchatkan, and endemic species, but the biodiversity of the islands, relative to each other and to the main- land, is unknown. Limited coastal regions of several of the larger, more strategi- cally positioned islands have been heavily impacted since the close of World War II by the construction of Russian military installations, but otherwise the islands re- main undisturbed, Only six islands are currently inhabited. Realizing the scientific value of a detailed biological survey of the islands of the Kuril Archipelago, and with financial support from the U.S. National Science Foundation, we have joined with Japanese scientists, primarily from the Sapporo and Hakodate campuses of Hokkaido University, and Russian scientists from the Institute of Biology and Soil Sciences, Russian Academy of Sciences, Far East Branch, Vladivostok, to conduct a six-year program designed to survey and inven- tory the 30 major islands of the Kurils (including the five primary isles of the Habo- mai group, see Fig. 1): the International Kuril Island Project (IKIP), focusing on plants, aquatic and terrestrial insects, spiders, freshwater and terrestria] mol- lusks, freshwater fishes, amphibians, and reptiles. Having completed six field sea- sons (1994-1999) of collecting, on al1 30 major islands, we are now able to provide some general distributional and zoogeographic infoumation. Here we repert specifi ically on the freshwater fishes. Prior to the work described here, at least 88 species of fishes (in 57 genera and 20 families) had been reported in freshwater habitats of the Kurils and adjacent re- gions (Hokkaido, Sakhalin Island, and Kamchatka), but only 19 species (11 genera and six families) were thought to occur in the Archipelago itself (Taranetz 1937; Kuronuma 1943; Berg 1948, 1949a, 1949b; M. K. Glubokovsky, personal communica- tion, 22 and 29 March 1993; Reshetnikov et al. 1997). Nine of these species were said to occur throughout the Kurils (six anadromous salmonids and osmerids, and three euryhaline gasterosteids), and, in addition to these, one was reported from the northern Kurils [an osmerid, Lb;pomesus oltdus (Pallas, 1814)] and three from the southern Kurils [the osmerids Hblpomesus nipponensis McAllister, 1963 and H jmponicus (Brevoort, 1856), and a gasterosteid, Pungitius pungititts sinensis (Guichenot, 1869)]. Three other species were reported from Iturup [a cyprinid, Tri- bolodon brandti (Dybowski, 1872), and two gobiids, Tridentiger obscurus (Tem- minck and Schlegel, 1845) and Gymnogobius urotaenia (Hilgendorf, 1879)], three from Shikotan [the gobiids Luciogobius guttatus Gil1, 1859, G),mn(rgobius moro- NII-Electronic Library Service JapaneseJapaneseSociety Society ofSystematicof Systematic Zoology 136 Theodore W. Pietsch et al. ranus (Jordan and Snyder, 1901), and G. castaneus (O'Shaughnessy, 1875)], and two from Kunashir (the gobiids Lucingobitts guttatus and (lp)mnogobius urotaenia). Ac- cording to M. K. Glubokovsky (persenal communication, 22 and 29 March 1993), only a few random collections of non-commercially important freshwater fishes had been made during the past 50 years, and these ef!brts had been confined to only three or four of the larger islands of the chain. The present analysis, based on an examination of some 39,269 specimens collected throughout the Archipelago, indi- cates the presence of 28 species in eight families and 12 genera. Eleven of these species, including two previously undescribed forms (Saruwatari et al, 1997; Stevenson 2000 and in preparation),