Date of Award

1995

Degree Name

Biological Sciences

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

Donald C. Tarter

Second Advisor

Thomas K. Pauley

Third Advisor

Dan K. Evans

Abstract

The grass pickerel, Esox american us vermiculatus LeSueur, is listed as Undetermined on the Vertebrate Species List of Concern in West Virginia. The reason for the West Virginia status is that lentic, vegetated habitats required for spawning by the grass pickerel are limited within the state and are being reduced by agricultural, residential, and industrial developments. Green Bottom Swamp, a naturally occurring wetland of 58 hectares, provides habitat for the grass pickerel. A proposed habitat alteration to add marshland by building dykes prompted this study. Information from this investigation will establish a baseline for reproductive activities of the grass pickerel prior to potential habitat perturbation at Green Bottom Swamp. The spawning act was not observed during the reproductive period. It was thought to have occurred in aquatic vegetation associated with the buttonbush (Cephalanthus occidentalis) community in late February to early March. One ripe female containing primary (mature), secondary, and tertiary eggs was collected on 26 February 1993. The threshold temperature for spawning is approximately 9°C. No yolk-sac larvae were found during the post spawning period. On 4 April 1995, 3 post yolk-sac larvae (18.0, 12.0, & 11.0mm TL) were collected. One juvenile grass pickerel (24.2 mm TL) was collected on 10 March 1993 and 43 juveniles (22.9 to 67.5 mm TL; mean= 37.3 mm TL) were found on 21 April 1993. The nursery area for juveniles was beds of Potamogeton crispus (curly pondweed). The estimated number of primary (mature) eggs was 3,167 (N = 1; 280 mm TL). The gonosomatic index (GSI) reached a maximum in late February (ripe female 4.31% and spent female 0.34%). Egg diameters (N =50) ranged from 1.40 to 2.15 mm (mean= 1.79 mm). The estimated incubation time for egg development was 8-12 days. Seasonal gonad histology confirmed trends exhibited in seasonal GSI. Based on seasonal GSI, histology, and young-of-the-year, spawning occurred in late February to early March. Morphometries varied significantly (p < 0.05) for length of pectoral ray, length of pelvic ray, and head length. Greater lengths were attributed to males. Meristics did not vary significantly (p < 0.05) between the sexes. Sex ratio did not deviate significantly (p < 0.05) from the expected 1:1 ratio.

Subject(s)

Grass pickerel - Reproduction.

Grass pickerel - West Virginia.

Green Bottom Wildlife Management Area (Cabell County, W. Va.)

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