Summer 2014 American Currents 2 THE NATIVE STREAM FISHES OF HAWAII Konrad Schmidt St. Paul, MN
[email protected] Several years ago at the University of Minnesota a poster The “uniqueness” of these species is due not only to the about Hawaii’s native freshwater fishes caught my eye. I high degree of endemism, but also includes their habitat, life was astonished to learn that for a tropical zone the indige- cycle, and evolutionary adaptations. Hawaii’s watersheds nous freshwater ichthyofauna (traditionally and collectively are typically short and small. The healthiest fish populations known as ‘o’opu) is incredibly rich in uniqueness, but very generally inhabit perennial streams located on the windward poor in species diversity, comprising only four gobies and (northeast) side of islands which are drenched with 100-300 one sleeper. Four of the five are endemic to Hawaii. How- inches of rainfall annually. Frequent and turbid flash floods, ever, recent research suggests the ‘o’opu nākea of Hawaii is called freshets, occur on a regular basis; between events, a distinct species from the Pacific River Goby, and is, there- however, stream visibility can exceed 30 feet. On the lee- fore, also endemic. In addition to these fishes, there are only ward, drier sides, populations do persist in some intermit- two native euryhaline species that venture from the ocean tent streams at higher elevations even though lower reaches into the lower and slower reaches of streams not far above may be dry for months or years. These dynamic streams are their mouths: Hawaiian Flagtail (Kuhlia sandvicensis) and continually and naturally in a state of recovery.