Wednesday October 6, 2010

It’s always nice to see native fish once in a while, like these tuleperch (Hysterocarpus traskii), which are the sole member of their genus and the only species of freshwater surfperch (marine-derived origin). Tuleperch once occurred throughout the Sacramento and San Joaquin rivers, and the San Francisco Bay estuary. The fish recorded in this underwater video belong to the subspecies (H. t. traskii) that occurs in the Sacramento-San Joaquin system. There are two other subspecies, one occurring in the Russian River (H. t. pomo) and the other in the Clear Lake watershed (H. t. lagunae). Tuleperch exhibit three body patterns: unbarred, narrow-barred, and broad-barred. One of the more interesting traits of tuleperch is that they are the only viviparous, freshwater fish native to California. All species of surfperch are viviparous, meaning that the females give birth to fully formed offspring like a mammal. In general, as a female tuleperch grows there is an increase in the size and number of young she produces (Baltz & Moyle 1982). Tuleperch tend to occupy deep pools with aquatic and overhanging vegetation (as seen in this video), and feed on invertebrates, plants, and zooplankton along the bottom of the streams. Unfortunately, they are not as common as the non-native centrarchids that now dominate many Delta fish communities.
Video source: FISHBIO

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