Melanoma Epizootic in Brown Bullhead Ameirus nebulosus

from Lake Memphremagog, VTC. R. Simpson1, V. S. Blazer1, C. M. Hahn1 and T. Jones2

OutlineI. Background

II. Results from 2014 and 2015 VT Fish and Wildlife surveys

III. Histology of normal vs affected skin

IV. Preliminary results from most recent USGS survey (2015)

V. Potential risk factors

Vermont

Quebec

Vermont

Lake Memphremagog

South Bay

Reports of Raised Black Skin Lesions

Beginning in 2013

“Black tar-like substance” on skin surface

Multiple locations: South Bay, Hospital Cove (main lake) – shallow

sites Black River Willoughby River Halls Creek

Bullhead Raised Black LesionsVTBB2-28

VTBB2-35

VTBB2-28

VTBB2-2

2014 Vermont State Survey

Hospital Cove June 2014 26% incidence of condition 73 bullhead collected by boat e-fishing

7 tissue samples collected for histology Dorsal spines for aging

Size Distribution of 2014 Sample

Total Length (mm)

Number of Fish

2015 Vermont State Survey South Bay

470 acre shallow bay

July 2015

28% incidence

75 brown bullhead collected by boat e-fishing

Normal Brown Bullhead SkinBM

Epidermis

DCT

Raised Melanistic Lesions: Melanoma

A Closer Look

A Closer Look

A Closer Look: Advanced Stages

2015 USGS Survey N = 50

20 normal-appearing 20 with raised black lesions 10 normal-appearing (another lake)

Sampled for: Contaminant analysis Molecular/transcriptome analysis – RNAlater In situ hybridization – PAXgene Histopathology Virology – Wild Fish Survey

Observations during USGS Field Sampling 2015

Invasive

VTBB2-2

VTBB2-2

Observations during USGS Field Sampling 2015

Metastasis

Gill

Gill arch

Potential Risk Factors UVB/Sunlight

Contaminants

Heredity Xiphophorus platyfish-swordtail hybrid

Infectious agent

Take away Reports began in 2013

Prevalence of melanomas confirmed

Began study on potential risk factors

Combination of UVB/sunlight radiation and contaminant exposure

What’s next?

Acknowledgements Kathy Spring, Darlene Bowling, Pam

Whittington, USGS, for histology technical support

Jud Kratzer and Len Gerardi, VT Fish and Wildlife, for fish collections