A Note on Cascade Climbing of Migrating Goby and Shrimp Postlarvae in Two Maui Streams

In this study, we documented cascade climbing rates of 133 and 230 postlarvae of Lentipes concolor (O‘opu alamo‘o) and Atyoida bisulcata (Opae kahaole), respectively, from two streams on the island of Maui, Hawaii. Climbing measurements and observations were made of postlarvae at the water-substrate interface in cascade habitats of constricted water flow. Both species were observed to move in short bursts of forward progression within or above the pulsing water-substrate interface. Goby postlarval climbing rates ranged from 0.04 – 1.50 cm s–1 and were slower than shrimp rates which ranged from 0.30 – 3.06 cm s–1. The high variability is attributed to the bursting movement behaviors exhibited by both species. During one night of monitoring, a mean of 9.4 shrimp min–1 were observed to climb along ~ 0.4 m stretch of the watersubstrate interface, resulting in conservative recruitment estimate of 564 shrimp h–1. Potential applications to stream management are discussed