Delta Smelt: Hypomesus Transpacificus Research Paper

Giovanni Adame

Mrs. Hofferth

Endangered Species Project

18 May 2015

Delta Smelt

        The Delta Smelt, otherwise known as Hypomesus transpacificus, is listed as critically endangered. Delta smelts are very tiny fish with adults averaging at a whopping 3 inches in length, the size of about a human finger. It’s apart of the minnow family and has a steel blue sheen on both of its sides. The Smelts have a slender body with almost translucent skin.

        The Smelt’s diet consists of zooplankton. Since the zooplankton eats the autotrophic phytoplankton, zooplankton are considered primary consumers. As the Delta Smelts devour the zooplankton, they are earning the title of secondary consumers.

Delta Smelts are endemic to the Sacramento-San Joaquin Delta in California, so this estuary is the only place they call home. They can tolerate waters with salinities from ten to twelve parts per thousand. However, when it comes time to spawn, the Smelts tend to have their young in freshwater channels.

        There are many factors that pose some serious threats against these little fishes. One stems from contamination of their habitat. Toxic substances are being secreted into the delta through runoff from agricultural farms and even civilizations in cities. In addition water projects along the rivers leading into the deltas cause quite a bit of harm. The water projects allow for intrusion of higher salinity water into the delta, in turn decreasing the amount of nursery and spawning areas available. Also, is the fact that these projects sometimes trap Smelts in water pumps and meeting their death. Another threat is that posed by competition. Many Exotic copepods, as well as some introduced clams, have been known to reduce the amount of zooplankton. As the zooplankton numbers decrease, the Smelts follow suit.

        I am connected to the deltas by the theory of six degrees of separation because of the freshwater that the Smelts reside in. They live in a fresh river runoff coming straight from the mountains in the form of the Sacramento-San Joaquin River. This river is used by countless agricultural and urban developments up and down California. The Sacramento-San Joaquin River supplies freshwater to over twenty-five million Californians. I indirectly affect the Smelt’s habitat because of the water projects used to get water for the produce that farmers grow and sell. There’s a chance that I have bought or eaten that produce. Furthermore, the estuary may have supplied some of the fresh water I have drunk.

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