Low prevalence of visual impairment in a coastal population of gray seals (Halichoerus grypus) in the Gulf of St. lawrence, Canada
Visual impairment is common in captive pin-nipeds (Sweeney, 1974; Ridgway et al., 1975; Stoskopf et al., 1983; Greenwood, 1985; Colitz et al., 2010a, 2010b), but its prevalence in the wild is currently unclear due to the limited number of published studies and inconsistent information in the relevant literature (e.g., Griner, 1983; Filer et al., 2003). Visual impairment is a broad cat-egory that includes pathological, parasitological, traumatic, or congenital conditions (e.g., Aguirre, 2004; Dailey et al., 2005). Although the preva-lence of specific conditions affecting pinniped vision (e.g., Leptospira pomona infection) may be under-reported, partly due to the difficulties of field diagnosis methods, general conditions (e.g., opacities, lesions, etc.) are reported most often (Stoskopf et al., 1985; Gerber et al., 1993; Aguirre, 2004). What is clear is that visual impair-ment reported in wild pinnipeds is usually associ-ated with the cornea, anterior chamber, iris, and lens (e.g., Smith et al., 1977; Stoskopf et al., 1985; Schoon & Schoon, 1992; Baker et al., 1998). However, this prevalence is likely because these are the most conspicuous structures to observers.
Kot, B.W., T. Morisaka, R. Sears, D. Samuelson and C.D. marshall. 2012. Low prevalence of visual impairment in a coastal population of gray seals (Halichoerus grypus) in the Gulf of St. lawrence, Canada. Aquatic Mammals 38:367-371.
Low prevalence of visual impairment in a coastal population of gray seals (Halichoerus grypus) in the Gulf of St. lawrence, Canada PDF (622 KB)
Article downloaded from: