Energy acquisition and retention by age-0 and age-1 paddlefishPolyodon spathula(Walbaum, 1792) in relation to size, growth, and rearing conditions in two Great Plains reservoirs and hatchery ponds

Abstract

The objective of this study was to investigate lipid accumulation and storage in age-0 and age-1 paddlefish Polyodon spathula (Walbaum, 1792) in relation to age, stock,year, and growth. Juvenile paddlefish were collected from three locations in North Dakota and Montana, USA, during July and August of 2011 and 2012 and proximate analysis was used to determine lipid content. RNA/DNA ratios were used as an index of growth rates. Differences in age-based lipid accumulation and storage in juvenile paddlefish suggest a split allocation between growth and lipid storage, with growth being the highest initial priority and emphasis on energy storage occurring at a larger size, later in life. Differences in lipid allocation between stocks indicate that allocation is influenced by hatchery/wild rearing conditions. Differences within and betweenyear-classes are consistent with field evidence observed in 2012 of a strong 2011 yearclass, and indicate that during productive times, paddlefish may allocate energy to both body growth and lipid reserves, and that allocation differs among years. The lack of a relationship between RNA/DNA ratio and lipid does not support a physiologically exclusive allocation strategy between growth and lipid. Evidence from this and other studies suggests rather that an emphasis on growth, some energy storage, and a large rostrum size in relation to overall fish length in age-0 and age-1 fish, may be adaptive in avoiding predation while accruing necessary energy reserves for overwintering.Although this study also provides reference information regarding proximate composition of wild and hatchery origin juvenile paddlefish, much more study is needed into the relationships among growth, low and high lipid groups, lipid allocation in juvenile paddlefish as well as the existence and timing of allocation changes between growth and storage. To aid in understanding paddlefish survival and year-class strengths, these relationships also need to be linked to inter-annual differences in early rearing environments for age-0 and age-1 fish.

Diet and Condition of Age‐0 Scaphirhynchus Sturgeon: Implications for Shallow‐Water Habitat Restoration

“…In contrast, those authors reported that mean and median lipid values were <1% during 2012, a lower water year resulting in a weaker year‐class. During 2014, the lipid values (mean and median values of 1.3% and 1.0%, respectively) for our largest category of wild‐caught fish (101–120 mm) were more comparable with the values from the weaker year‐class reported in Hemingway and Scarnecchia (). During 2015, however, our lipid values (mean and median values of 2.4% and 2.3%, respectively) were more comparable with the values from their exceptionally strong year‐class.…”

“…During 2015, however, our lipid values (mean and median values of 2.4% and 2.3%, respectively) were more comparable with the values from their exceptionally strong year‐class. These comparisons may provide additional evidence that 2014 and 2015 could represent weak and strong year‐classes, respectively; however, the results of Hemingway and Scarnecchia () may not be directly comparable with our age‐0 sturgeon results in the lower Missouri River.…”

“…); the authors suggested that wet years may provide suitable conditions for age‐0 Shovelnose Sturgeon foraging as well as for migration and spawning of adult females. In Lake Sakakawea, North Dakota, Hemingway and Scarnecchia () documented significant interannual differences in age‐0 Paddlefish lipid levels, which also coincided with strong and weak year‐classes. Shortnose Sturgeon Acipenser brevirostrum cohort abundance in the Hudson River, New York, varied nearly 10‐fold over the course of 20 years, but consistent recruitment coupled with occasional strong year‐classes led to population recovery (Woodland and Secor ).…”

“…A biologically meaningful value for lipid content in wild age‐0 sturgeon is therefore still lacking, although our data may help identify one. Hemingway and Scarnecchia () reported that age‐0 Paddlefish > 150 mm in Lake Sakakawea yielded mean and median lipid values of approximately 4% and 2.8%, respectively, during 2011 when the lake experienced record high water, which resulted in an exceptionally strong year‐class. In contrast, those authors reported that mean and median lipid values were <1% during 2012, a lower water year resulting in a weaker year‐class.…”

“…Lipid assessments have been conducted on other young fishes including juvenile Shovelnose Sturgeon (Kappenman et al. ) and age‐0 Paddlefish Polyodon spathula (Hemingway and Scarnecchia ). We obtained a gross measure of body condition by performing a modified Folch extraction (Folch et al.…”