Myxobolus cerebralis, Hofer, 1903

Fetherman, Eric R. & Avila, Brian W., 2022, Habitat associations of rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta fry, Journal of Fish Biology 100 (1), pp. 51-61 : 54

2.5 | M. cerebralis sample collection

Although stocking of M. cerebralis –resistant O. mykiss fry has resulted in increased survival and recruitment ( Fetherman & Schisler, 2016), the pathogen continues to persist in the upper Colorado River and remains an obstacle for reestablishing O. mykiss in the system. In October, up to five S. trutta fry and five O. mykiss fry, dependent upon availability, were collected from each of the four abundance estimation sites at Sheriff Ranch, Red Barn and Hitching Post as part of a long-term monitoring study of M. cerebralis infection and prevalence in wild fish populations. In addition, one to two fry per species per site were collected from the 16 single-pass count sites in the Sheriff Ranch, Kinney Creek, Red Barn and Hitching Post areas. Collecting fry in October ensured full development of myxospores following previous natural exposure to the triactinomyxon, the infectious waterborne stage of the parasite ( Hedrick & El-Matbouli, 2002) released by T. tubifex . Myxospores were enumerated ( O'Grodnick, 1975) from whole fish using the pepsin–trypsin digest method ( Markiw and Markiw & Wolf, 1974) by the CPW Aquatic Animal Health Laboratory (Brush, Colorado).