Date of Graduation

Fall 2020

Degree

Master of Science in Biology

Department

Biology

Committee Chair

Quinton Phelps

Keywords

larval fish, Scaphirhynchus sturgeon, sampling, habitat, Missouri River, Mississippi River

Subject Categories

Biodiversity | Zoology

Abstract

Humans have been altering the natural ecosystem for centuries. These alterations provide many socioeconomic benefits (e.g., navigation and flood-control). However, these alterations can have negative ecological consequences. Large rivers across the country have been manipulated to facilitate various human activities. Rivers are dynamic systems governed by various abiotic and biotic factors. Ultimately these alterations change the natural biogeochemical cycles and reduce available habitats. These impacts likely affect riverine fishes’ ability to carry out their lifecycle. Riverine organisms, and particularly fish, have adapted to survive in free-flowing systems. Population dynamics (i.e., recruitment, growth and mortality) are the basis of fisheries management. Understanding these parameters allows for proper fisheries management. Larval fish data are often used to infer fish reproduction, recruitment and range. As such, it is important to understand and effectively sample larval fishes. Few studies have evaluated methods for larval fish sampling in large rivers. As such, we sought to develop a sampling method that effectively and efficiently captures free-drifting fish larvae in large rivers. We then used this method to sample Scaphirhynchus sturgeon in the Missouri and Mississippi rivers. We were able to capture a wide range of free-drifting larval fish taxa in our drift nets. Our nets were able to capture 12 of 16 (75%) fish families present in the Middle Mississippi River. We then used Scaphirhynchus sturgeon catch information to model various spatial and temporal interactions. Of the models evaluated, year to year variations best explained Scaphirhynchus sturgeon catch rates. Understanding fish early-life history is imperative for proper fisheries management. We present a sampling methodology for collecting free-drifting larval fishes. Further, we applied these methods to evaluate Scaphirhynchus sturgeon drift dynamics in the Missouri and Mississippi rivers. These methods have broad application potential and can help guide various management strategies.

Copyright

© Hae Hyun Kim

Open Access

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