AUTHORS: Theodore Goetz, Missouri Department of Conservation
ABSTRACT: Skipjack Herring (A. chrysochloris) is a Missouri native species of migratory fish found in the Mississippi river and surrounding large river waterways. Due to a lack of information on its status, it is listed as State Unidentifiable on the Missouri Species of Conservation Concern list. This study will investigate the life history of the Skipjack Herring by collecting fish across a broad reach of the Mississippi River, from within varying levels of impoundment, from April through September 2024 and 2025. Skipjack will be collected as bycatch through collaboration with a number of preexisting programs and efforts such as LTRM and LTEF, as well as opportunistic targeted efforts of electrofishing. Workup of A. chrysochloris will take place at the Big Rivers and Wetlands field station, and will include length and weight measurements, extraction and processing of otoliths, removal of a caudal fin clip, removal and processing of a leading pectoral fin spine, weight and identification of gonads, and refreezing the remains for sequential analysis. A choice structure analysis will be completed between otoliths and pectoral fin spines. Samples taken will be used for the calculation of age, growth, sex, gonadosomatic index, CPUE, mortality, and PSD. These metrics will be evaluated to better understand reproductive strategies and timing, age range, rate of growth, condition across increased impediment, and the impact of the interruption of ecological processes caused by barriers and habitat loss along fish migratory routes within the Mississippi river system. A. chrysochloris is also one of the two sole hosts for the parasitic larvae of native mussels Ebonyshell (Federally Endangered) and Elephantear (Missouri State Endangered). Skipjack herring are extremely difficult to keep for artificial propagation, which makes knowledge of their life history all the more significant to the management of these two mussels.
