Document Type

Article

Department/Program

Virginia Institute of Marine Science

Publication Date

1994

Journal

Fishery Bulletin

Volume

92

Issue

2

First Page

254

Last Page

261

Abstract

Restriction-fragment length polymorphism (RFLP) analysis of mitochondrial mtDNA was used to identify morphologically similar eggs of spring spawning sciaenids in lower Chesapeake Bay. During spring 1990 and 1991, ichthyoplankton surveys were conducted in lower Chesapeake Bay to estimate seasonal egg production and population biomass of black drum, Pogonias cromis. Rearing experiments indicated that at least three species of sciaenid (silver perch, Bairdiella chrysoura; weakfish, Cynoscion regalis and P. cromis) were spawning in the survey area during both years. Specific identification of eggs based on previously published ranges of outside egg diameter (OED) were not reliable because of considerable overlap in diameter distributions. However, analysis of weekly OED frequencies revealed the presence of three modes which differed in temporal occurrence, suggesting the products of three species. Genetic typing of eggs using RFLP analysis of mtDNA confirmed the presence of three species, but demonstrated that eggs of certain size classes represented two species. These results illustrate that reliance on previously published ranges of egg diameter for specific identification of spring-spawning sciaenids may overestimate the spawning biomass of black drum in Chesapeake Bay by as much as 50% owing to misidentification of weakfish eggs.

Keywords

Early Larvae; Electrophoretic Identification; Cynoscion-Regalis; Atlantic Coast; Weakfish

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