Document Type

Thesis - Open Access

Award Date

1976

Degree Name

Master of Science (MS)

Department

Wildlife and Fisheries Science

Abstract

Four hundred eighty-four paddlefish (Polyodon spathula) were captured 26 June 1975 to 11 August 1976 from an unaltered stretch of Missouri River in South Dakota. Vital statistics were measured on all fish, 171 were sacrificed during the analysis of food habits, and 301 fish were tagged and released. Paddlefish were located by observation, gill netting, and snagging. Paddlefish were primarily found downstream from submerged sandbars from late spring to early fall. The crests of the sandbars were 0.1 to 1.0 m deep and immediately downstream, the depth was 1.5 to 4.5 m, and the current velocity was 0 to 0.3 m/sec. Paddlefish were located in slow or dead water areas which as depths of over 3 m during late fall or early spring. All paddlefish concentration areas from late fall to early spring were adjacent to channels. Paddlefish in channelized river appeared to inhibit slow or dead water areas adjacent to the river channel, oxbow lakes, and non-flowing tributaries. Halo-like bands in dentary bone cross sections may be produced as a result of the food habits of paddlefish. The eye to fork length was a more valid index of paddlefish growth than total length or fork length. Factors to allow conversion of total length and fork length, to eye to for length were calculated. The mean weight and mean length of paddlefish were 5,900 g and 720 mm, respectively. The length – weight formula was w= -463.67 + 8.24 L + 0.085 L² or in logarithmic terms, Log w = -3.85 + (2.66) )Log L) : where w = weight (g) and L = eye to fork length (mm). The average condition factor, K, was 1.47, and the average K for female paddlefish was 1.45 and for male paddlefish 1.48. Factors to allow conversion of X values calculated from total length and fork length to eye to fork length were given. K values increased as length of the fish increased until the fish were approximately 700 mm long. K values decreased with increased length thereafter. K values were highest during spring and fall. Females were significantly heavier and longer than males in any given age-class. Four stages of ovary maturation were described, and few female paddlefish with mature ovaries were captured. The sex ratio for the population was estimated to be 0.85 males to 1 female. The presence or absence of tubercles on the dorsal surface of paddlefish was not an indicator of sex. Thirty-five and one-half percent of all fish examined had scars on their bodies, and 27.4% of these fish had lost part or all of their rostrum. Sixty-seven percent of the fish tagged which were recapture traveled downstream, 26% upstream, and 7% stayed in the same area. Three fish ranged 680 to 780 km within 3 to 8 months after capture. Food of paddlefish was strongly indicated. Vernal and autumnal feeding peaks were evident, and feeding nearly ceased from July to September. Paddlefish appeared to feed continuously when food consumption levels were high and non-food items composed 37 to 78%, by volume, of the total stomach contents.

Library of Congress Subject Headings

Paddlefish
Fishes

Description

Includes bibliographical references (pages 79-82)

Format

application/pdf

Number of Pages

107

Publisher

South Dakota State University

Rights

No Copyright - Non-Commercial Use Only
http://rightsstatements.org/vocab/NoC-NC/1.0/

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