Date of Award

Winter 2006

Project Type

Thesis

Program or Major

Zoology

Degree Name

Master of Science

First Advisor

David Berlinsky

Abstract

Recruitment of American shad (Alosa sapidissima) and rainbow smelt (Osmerus mordax) has steadily declined over the last few decades, possibly due to the construction of physical impediments to migration and increases in anthropogenic pollution. In order to elucidate environmental parameters influencing early life stages of anadromous fish, both laboratory and field studies were conducted. The effects of abiotic factors, including dissolved oxygen (DO), pH, salinity, nitrate, and phosphate, on hatch and survival of larval and juvenile American shad and rainbow smelt were examined in laboratory studies. Field studies on shad emigration were conducted in the Exeter River, and studies on smelt egg viability were conducted in the Winnicut and Squamscott Rivers.

Extremely low DO saturation (20%, 1.74 mg I-1) was found to be detrimental to shad larvae, and all levels at and below 80% (6.94 mg I-1) caused a reduction in egg viability. Low pH (4) reduced egg and larval viability. Larval survival decreased with increased salinity, but egg hatch was unaffected by salinities up to 30 ppt. Nitrates and phosphates had no effect on eggs or larvae.

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