Fishes < Migration in the sea — oceanodromous species > Invertebrates
Migration in freshwater — potamodromous species
Migration between fresh- and saltwater — diadromous species — Fishes: Migration in freshwater — potamodromous species

Fish moving entirely within freshwater exhibit seasonal return movements to spawning areas, usually located upstream. Within rivers, this is called potamodromous. If feeding areas or spawning areas are located in lakes, this is called limnodromous. Besides bony fish (Osteichthyes), this migration pattern is observed in Cyclostomes (Lampreys: Petromyzodontidae) and even freshwater sting rays (Potamotrygonidae: Chondrychthyes) that migrate in the Amazon, the Mekong and the Niger river. Up to now, around 100 limno- and potamodromous species have been identified (see Table 4.9), but the scattered literature about migration in tropical river systems has not yet been evaluated. For example, in the middle Indus there seem to be "upstream migrations of three major carps Labeo rohita, Catla catla and Cirrhinus mrigala, the two carnivorous species Mystus aor and Mystus seenghala, the catfish Wallago attu and the snakehead Channa marulius. The large catfish Bagarius bagarius, a species that is widely distributed in the subcontinent, may also [...] move upstream" (Reeves & Smith 1997, p. 13). While this information needs careful examination, the disastrous impacts of dams on a great variety of highly productive tropical species is now a sad fact: major spawning areas of mahseers (Tor putitora and T. tor), holy carps in the eyes of Hindus, have been destroyed by dams in the upper reaches of rivers in the South Asian subcontinent (Nautiyal 1984, 1989).

The complexities of migration within the Mekong river were elucidated by an extensive field study in 1993 at Ban Hang Khone, an important fishing village on Khone Island just below the great waterfalls of the Mekong River at Lee Pee, southern Laos (Roberts 1993). Roberts identified three migratory periods, late January-February, May-July, and November-December. The study diagnosed a gradual decline of fisheries for all observed 93 species to about 20% of what it was in 1970. The endemic Mekong freshwater herring "pa mak pang" (Laotian shad: Tenualosa thibaudeaui), formerly one of the most abundant species, had almost disappeared, and is now red-listed as "Endangered" (Table 4.11). The decline is attributed to deterioration of flooded forest habitat, overfishing and destruction of spawning grounds by upstream dam construction. The Mekong river is also home to the only fish species listed in CMS Appendix I, the endangered giant catfish (Pangasius gigas, listed under Pangasianodon gigas). The Mekong river is still considered "a pristine river, free of dams and large-scale water diversion projects, and the water quality is generally good" (Hill & Hill 1995, p. 1). But in the light of huge development projects, co-ordinated by the Mekong River Commission, the authors conclude that "preservation and management of Mekong fish faunas will depend upon incorporating spatial information into decisions about [...] anthropogenic change" (l.c., p.1).

Probably the worst conservation status is observed among the sturgeons (Acipenseridae), which are actually driven to the brink of extinction by illegal fishing, habitat degradation and pollution. Following a proposal of the Federal Republic of Germany (1999), 6 potamodromous sturgeon species (Acipenseridae) have been added to CMS Appendix II, together with 18 anadromous sturgeons (see below). Further endangered potamodromous species are listed in Table 4.11. Research on the present conservation status is needed for the six additional species listed as "Data Deficient" (Table 4.12). In addition, it is necessary to keep in mind that dam construction can affect entire populations or whole species by irreversible blocking of upstream migration.

Tab. 4.11: Threatened diadromous and potamodromous fish, their CMS status and number of range states Tab. 4.11: Bedrohte diadrome und potamodrome Fische mit CMS Status und
Family Scientific name Common name RL
Migration Range states RL 2000 CMS
Acipenseriformes Acipenseridae Acipenser baerii baerii Siberian sturgeon VU anadromous 3 N.L.
Acipenser brevirostrum Shortnose sturgeon VU anadromous 2 N.L.
Acipenser dabryanus Yangtze Sturgeon CR anadromous 1 N.L.
Acipenser fulvescens Lake sturgeon VU potamodromous 2 App. II
Acipenser gueldenstaedtii Azov-Black Sea sturgeon EN anadromous 4 App. II
Acipenser medirostris Green sturgeon VU anadromous 3 App. II
Acipenser mikadoi Sakhalin sturgeon EN anadromous 3 App. II
Acipenser naccarii Adriatic sturgeon VU anadromous 6 App. II
Acipenser nudiventris Barbel sturgeon CR anadromous 2 App. II
Acipenser oxyrinchus desotoi Gulf sturgeon VU anadromous 2 N.L.
Acipenser persicus Persian sturgeon VU potamodromous 3 App. II
Acipenser ruthenus Sterlet sturgeon VU potamodromous 1 App. II (Pop)
Acipenser schrenckii Amur sturgeon EN anadromous 3 App. II
Acipenser sinensis Chinese sturgeon EN anadromous 1 App. II
Acipenser stellatus Sevruga EN anadromous 4 App. II
Acipenser sturio Baltic sturgeon CR anadromous 33 App. II
Acipenser transmontanus Columbia sturgeon EN anadromous 1 App. II
Huso dauricus Kaluga EN anadromous 3 App. II
Pseudoscaphirhynchus fedtschenkoi Syr Darya sturgeon CR potamodromous 3 App. II
Pseudoscaphirhynchus hermanni Dwarf sturgeon CR potamodromous 2 App. II
Pseudoscaphirhynchus kaufmanni Amu Darya shovelnose sturgeon EN potamodromous 3 App. II
Polyodontidae Polyodon spathula Mississippi paddlefish VU potamodromous 2 N.L.
Psephurus gladius Chinese paddlefish CR potamodromous 1 N.L.
Clupeiformes Clupeidae Alosa alabamae Alabama shad EN anadromous 1 N.L.
Tenualosa thibaudeaui Laotian shad EN potamodromous 4 N.L.
Cypriniformes Cyprinidae Barbus capensis Clanwilliam yellowfish VU potamodromous 1 N.L.
Labeo seeberi Clanwilliam sandfish CR potamodromous 1 N.L.
Perciformes Gobiidae Lentipes whittenorum   VU amphidromous 1 N.L.
Sicyopus auxilimentus   VU amphidromous   N.L.
Stiphodon surrufus   VU amphidromous   N.L.
Terapontidae Bidyanus bidyanus Bidyan perch VU potamodromous 1 N.L.
Salmoniformes Galaxiidae Galaxias argenteus Giant kokopu VU amphidromous 1 N.L.
Galaxias johnstoni Clarence galaxias CR catadromous 1 N.L.
Galaxias postvectis Shortjaw kokopu VU amphidromous 1 N.L.
Osmeridae Hypomesus transpacificus Delta smelt EN anadromous 1 N.L.
Retropinnidae Prototroctes maraena Australian grayling VU amphidromous 1 N.L.
Salangidae Neosalanx regani Ariakehimeshirauo VU anadromous 1 N.L.
Salmonidae Coregonus huntsmani Atlantic whitefish VU anadromous 2 N.L.
Hucho hucho Danube salmon EN potamodromous 13 N.L.
Salvelinus confluentus Bull trout VU anadromous 2 N.L.
Siluriformes Pangasiidae Pangasius gigas Giant catfish EN potamodromous 6 App. I
Petromyzontiformes Petromyzontidae Eudontomyzon hellenicus Greek brook lamprey VU limnodromous 1 N.L.
Mordacia praecox Non-parasitic lamprey VU potamodromous 1 N.L.
Pristiformes Pristidae Pristis microdon Great-tooth Sawfish CR amphidromous 5 N.L.
Pristis perotteti Largetooth Sawfish CR amphidromous 11 N.L.
Fishes < Migration in the sea — oceanodromous species > Invertebrates
Migration in freshwater — potamodromous species
Migration between fresh- and saltwater — diadromous species

This document should be quoted as part of the publication "Riede, K. (2001): The Global Register of Migratory Species ­ Database, GIS Maps and Threat Analysis. Münster (Landwirtschaftsverlag), 400 pp." + CD

 by Klaus Riede