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Diseases of Aquatic Organisms

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DAO 150:103-124 (2022)  -  DOI:

Black eye syndrome and a systemic rickettsia-like organism in Alaskan Chionoecetes spp. crabs, including normal eyestalk microanatomy

Theodore R. Meyers1,*, Richard Morris1, Tyler M. Jackson2, Julia N. Dissen3, Laura M. Slater4, Maya L. Groner5

1Juneau Fish/Shellfish Pathology Laboratory, Commercial Fisheries Division (CFD), Alaska Department of Fish and Game (ADF&G), Juneau, AK 99811-5526, USA
2Shellfish/Groundfish Biometrics, CFD, ADF&G, Kodiak, AK 99615-7400, USA
3CFD, ADF&G, Anchorage, AK 99518-1565, USA
4CFD, ADF&G, Kodiak, AK 99615-7400, USA
5Prince William Sound Science Center, Cordova, AK 99574, USA
*Corresponding author:

ABSTRACT: A black eye syndrome (BES) was discovered in both captive and wild populations of Alaskan snow crabs Chionoecetes opilio and Tanner crabs C. bairdi. Field prevalences ranged from 0.37% (n = 594/161295) to 19.6% (n = 62/316) in snow crabs from the eastern Bering Sea and from 0.09% (n = 15/16638) to 0.7% (n = 133/18473) in Tanner crabs from the same trawl samples, with a slightly greater percentage (1.4%, n = 57/3945) in Tanner crabs from the Aleutian and Kodiak islands fisheries in the Gulf of Alaska. BES is not associated with crab mortality and has 2 distinct manifestations: abnormal black foci of internal eye pigment with no discernible histological lesions, which, in many cases, is followed by corneal shell disease with ulceration and distal eyestalk erosion. It is assumed for this study that these are early and late stages of BES that are somehow related. Our results suggest that early stages of abnormal pigmentation are noninfectious, possibly related to changing ocean conditions affecting crab endocrinology and neuropeptide control of secondary eye pigment. Potential light-induced photoreceptor damage of harvested crabs with dark-adapted eyes is another anthropogenic factor possibly contributing to the early changes in eye pigmentation. Normal eyestalk microanatomy specific for Chionoecetes spp. is provided as necessary baseline information for future studies. Early in the study, an unreported rickettsia-like organism (RLO) was discovered infecting dissected black eyestalks submitted for examination from 5 of 6 dead snow crabs, suggesting association with BES. Subsequent samples indicated the RLO was systemic, infected both black and normal-appearing eyestalks, and was unrelated to BES. However, the multiorgan infection and histopathology indicated the RLO could be a primary pathogen of snow crabs.

KEY WORDS: Black eye syndrome · Rickettsia-like organism · Chionoecetes spp.

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Cite this article as: Meyers TR, Morris R, Jackson TM, Dissen JN, Slater LM, Groner ML (2022) Black eye syndrome and a systemic rickettsia-like organism in Alaskan Chionoecetes spp. crabs, including normal eyestalk microanatomy. Dis Aquat Org 150:103-124.

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