Multitiered Health Assessment of Atlantic Menhaden in the Pamlico River, North Carolina

Abstract

During the fall of 2001 and 2002, Atlantic menhaden Brevoortia tyrannus were collected from several creeks in the Pamlico River, North Carolina, to investigate recent fish kills and ulcerative skin lesions. High skin lesion prevalence (>50%) was associated with the Atlantic menhaden kills in fall 2001, whereas there were no fish kills in fall 2002 and skin lesion prevalence was lower (< or =50%). Indicators of tissue damage (histopathological analyses of gills, heart, liver, intestine, and anterior kidney), body condition (liver somatic index), and immune status (transforming growth factor-beta [TGF-beta] messenger RNA [mRNA] production, hematology, plasma chemistry, and splenosomatic index) were compared between Atlantic menhaden with and without ulcerative skin lesions in fall. Atlantic menhaden with ulcerative skin lesions had significantly higher liver somatic indices, neutrophil and monocyte percentages, and splenic mononuclear cell TGF-beta mRNA levels than did fish without lesions. Hematocrit values, plasma protein, and Ca concentrations were significantly lower in fish with ulcerative skin lesions than in those without. The indicators used in this study at multiple levels of biological organization have provided valuable baseline data for understanding the health status of lesioned and nonlesioned Atlantic menhaden in the Pamlico River.