The Robert G. Brownlee spent January and February docked in Antioch, serving the many schools of the North Bay and giving them a treasured experience out on the beautiful Delta waters. The ecosystem is completely different than the much saltier waters off Redwood City in South San Francisco Bay. A good example of this was the recent catch of Hypomesus nipponensis, or the Japanese Smelt.
This little fish prefers fresh water, and it therefore limited by the ocean's salt that travels into San Francisco Bay and towards the Delta. The little fish is beautiful, but is in fact an introduced species in the Delta and yet another problem for the region's struggling native species (e.g. the endangered Delta Smelt). More than half of the fish species in the Delta are introduced. Combined with the fact that over 90% of the region's invertebrates are non-native as well, it is easier to understand why invasive species is one of the top 5 threats to biological diversity.
Like many introduced species, this one was brought to the region on purpose by the California Department of Fish & Game. In 1959 millions were imported from Tokyo and fed into several of the State's reservoirs. Until recent years it was thought acceptable to stock non-native species for recreational fishing purposes, and as in this case introduce non-native fish as food for these same recreational fish. By the mid-1990s, however, they were appearing in the Delta. |
