Temperature, Hatch Date, and Prey Availability Influence Age-0 Yellow Perch Growth and Survival

Throughout their range, Yellow Perch Perca flavescens are an important ecological and economic component of many fisheries, but they often exhibit highly variable recruitment. Much research effort has been devoted to better understanding the mechanisms responsible for these erratic recruitment patterns, yet few studies have examined this process at the detail necessary to reveal complex interactions that may exist across multiple early life stages. Our current understanding of the early life recruitment patterns of Yellow Perch suggests a strong abiotic component. Using existing information, we developed three working hypotheses to examine Yellow Perch recruitment at two larval stages (5–14 and 15–24 d old) and to further identify the overarching mechanisms (abiotic versus biotic) related to Yellow Perch recruitment in 332-ha Pelican Lake, Nebraska, during 2004–2012. Larval Yellow Perch growth and mortality were largely regulated by hatching date, temperature, and zooplankton availability. The growth of young larval Yellow Perch (5–14 d old) was positively related to temperature and hatch date; that of old larval perch (15–24 d old) was positively related to water temperature and postlarval age-0 (≤25 mm TL) Yellow Perch density but negatively related to the available preferred zooplankton biomass. Mortality was inversely related to total zooplankton biomass and water temperature. Our results describe a model with two potential Yellow Perch recruitment bottlenecks, one immediately posthatch that is regulated by hatch date and temperature and another during the older larval stage that is regulated by temperature and zooplankton. Understanding the mechanisms involved in determining fish recruitment or year-class strength has long been a chal­ lenge in fisheries science. Although much progress has been made to isolate these mechanisms, many studies are site spe­ cific or species specific or both (Claramunt and Wahl 2000). Year-class strength is often determined during the early life stages in fish (Rice et al. 1987) due to the low percentage (<1%) of fish that survive past this stage (Chambers and Trippel 1997). Despite much effort to identify overall patterns in recruitment within a species, few consistent patterns typ­ ically emerge. In some cases, patterns may be detected but are weak and typically provide little information of proximate or ultimate mechanisms relating to recruitment. Thus, broad landscape-type studies can provide insight as to which fac­ *Corresponding author: [email protected] 1Present address: Victoria University Coastal Ecology Lab, School of Biological Sciences, Victoria University of Wellington, Post Office Box 600, Wellington 6012, New Zealand. Received October 25, 2013; accepted January 14, 2014 tors may be involved in the recruitment process, but they lack the resolution to identify when and how they are affecting the population. Recruitment is most likely driven by a combination of the abiotic and biotic factors experienced at each stage of life, com­ plicating the process of determining which factors are most responsible for structuring fish communities via recruitment. Interannual differences also mask patterns related to recruit­ ment in fish populations, and those differences are difficult to detect with many statistical approaches. As a result, more information on the ultimate mechanisms limiting fish recruit­ ment is imperative during the critical early life period, and more long-term in-depth studies are needed to acquire such informa­ tion. Better understanding of processes involved in regulating 845 D ow nl oa de d by [ U S E PA L ib ra ry ] at 0 6: 55 1 4 Ju ly 2 01 4