Size-specific growth and mortality of juvenile yellow perch in southwestern Lake Michigan

Yellow perch have experienced widespread recruitment failure within Lake Michigan since the early 1990s. Efforts to explain annual recruitment variability have primarily focused on the first year of growth, while the juvenile life stage has largely been neglected. Juvenile yellow perch, age-0 through age-2, were collected annually from 2006–2010 in Illinois waters of Lake Michigan to assess temporal variability of size-at-age and size-selective mortality. Age-0 and age-2 total length at capture differed significantly between years with a maximum difference of 4.4 mm and 11.2 mm, respectively. First winter size-selective mortality was not observed for any year-class, however size-specific growth, with larger individuals growing faster than smaller counterparts, occurred during the first winter for all year-classes but 2006. Size-selective mortality was documented between age-1 and age-2 of the 2006 year-class with yellow perch less than 70 mm at age-1 not surviving through age-2. Though population level effects remain unknown, size-specific growth and mortality during the juvenile life stage may influence the size structure and year-class strength of yellow perch in southwestern Lake Michigan. Identification of size-selective mortality occurring beyond the first growing season highlights the significance of rapid growth during early life and the importance of investigating whole life stages to identify factors influencing year-class strength.