Monthly Abundance Indices

Fall Midwater Trawl indices for age-0 striped bass (Morone saxatilis), delta smelt (Hypomesus transpacificus), longfin smelt (Spirinchus thaleichthys), American shad (Alosa sapidissima),splittail (Pogonichthys macrolepidotus), and threadfin shad (Dorosoma petenense) from 1967-2018; please note that no surveys were done in 1974, 1979, and September and December 1976.

The September 1976 index was calculated by taking a quotient of the respective September and October indices (September/October) for pre-Corbula amurensis years 1967-1973, 1975, 1977-1978, 1980-1987 then averaging the quotients.

This mean quotient was then multiplied by the respective 1976 October index to generate the September index. The 1976 December index was calculated for each species by averaging the 1976 November and 1977 January indices.

In addition, due to the low number of stations sampled in Nov. 1969, the 1969 Nov. index is the average of the October and December 1969 index.

Single Table View (for downloading)