Theses and Dissertations


Title: Habitat use and tag retention of juvenile shovelnose sturgeon, a surrogate species for Alabama sturgeon

Name: Taylor, Marilyn Yvonne

Degree: MS

Chair: Elise R. Irwin

Resides:

University: Auburn University

Location: Auburn, Alabama

Date: 2004

Pages: 47

Keywords: Habitat,tag retention,juvenile,shovelnose sturgeon,Alabama sturgeon

Abstract:

Sturgeon species worldwide are imperiled. Habitat use and tag placement and survival data could be used to conduct more efficient stock enhancement programs for reintroduction of sturgeon. Alabama sturgeon Scaphirhynchus suttkusi are endangered and extremely rare, therefore, a surrogate, shovelnose sturgeon S. platorynchus, was used to determine juvenile habitat use and tag placement and survival. Habitat experiments were conducted using a large sinuous, flowing stream tank in a laboratory setting where substrata and cover were manipulated. A series of pilot studies (three fish densities x day/night = six trials) were conducted in a bare tank (no habitat or flow) to determine density effects (number of fish), potential tank effects (position in tank), trial time frame (seconds), diel differences (day versus night) and method of data collection (systematic or random). We incorporated a modified Ivlev electivity index (Powell modification) to compare factors. It appeared that density effects were important to distribution in the bare tank trials, whereas, higher density resulted in apparent tank position effects. Therefore, to account for variation in flow (upstream to downstream) and potential tank effects, a replicated 4x4 Latin Square design was incorporated for habitat trials using low densities offish (n = 8). Fish selected sand substrata, with or without cover, more than the gravel/pebble mix substratum with or without cover. These results are consistent with other studies of shovelnose sturgeon. To determine tag placement, retention rates and survival rates, 34 fish ranging in size from 220 mm to 346 mm standard length were tagged with Passive Integrated Transponder (PIT) tags (11 mm) in the left lateral muscle between the dorsal and lateral scutes anterior to the dorsal fin. Tag retention was recorded daily for 32 d. Tag entry wounds healed within nine days and initial tag retention was 100%. Post tagging (129d) retention was 89%, and after 146 days tag retention declined to 79%. Tag retention dropped to 71% after 225 days post tagging. Tag retention was unrelated to fish size. Mortality related to the PIT tagging process was 0%. These findings are significant in aiding the management plan for the Alabama sturgeon restoration plan.

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