The First Record of Bigscale Logperch and Range Expansions of Smallmouth Buffalo, White Crappie, and Gizzard Shad in Arizona

Bigscale Logperch Percina macrolepida is reported and substantiated for the first time in Arizona. A single specimen was collected during a routine survey of Cow Springs Lake on September 26, 2017, preliminarily identified as Percina sp . , preserved, and retained for species identification. We verified the specimen was a Bigscale Logperch through genetic analysis. Review of published literature and the U.S. Geological Survey Nonindigenous Aquatic Species Database suggests that this is the first known occurrence of Bigscale Logperch in Arizona. Further, three additional non-native species were detected during our sampling events on June 21 and September 26, 2017—Smallmouth Buffalo Ictiobus bubalus , White Crappie Pomoxis annularis , and Gizzard Shad Dorosoma cepedianum —representing the first collection of these species in the Little Colorado River basin that we are aware of. We recommend further evaluation of the ecology, distribution, and abundance of these four non-native species to better understand their effect on the native fishes of the watershed and the likelihood of establishment in the watershed and elsewhere in Arizona.

Potential Effects of Age, Population, and Latitude on Precision of Scale and Otolith Age Estimates of White Crappie in Minnesota

We calculated between-reader precision of ages estimated with scales and whole otoliths (sagittae) of White Crappie Pomoxis annularis for 10 Minnesota populations, and determined effects of population and mean age on precision. For all samples combined, two experienced readers counted the same number of annuli on 91% of the scales and 92% of the whole otoliths. Mean coefficients of variation equaled 1.8% between scale readers and 3.0% between whole otolith readers. We detected no systematic age-bias between readers of each structure. Agreement between scale readers differed among populations, ranging from 67 to 100% among populations (median = 89%), but agreement also decreased with increasing scale age in six of these populations. Agreement between readers of whole otoliths was unaffected by increasing age of White Crappie, but agreement ranged from 39 to 100% among populations. When compared with other studies, latitude had no influence on precision of whole otolith ages because precision in the Minnesota populations differed little from precision reported for populations in Kentucky and Mississippi. Latitude could be affecting precision in scale age estimates because precision was usually better for the Minnesota populations than for populations in Oklahoma, Kentucky, and Mississippi; however, differences in viewing methods and reader competencies could also explain geographical differences.

Histopathologic evaluation of postmortem autolytic changes in bluegill (Lepomis macrohirus) and crappie (Pomoxis anularis) at varied time intervals and storage temperatures

Information is lacking on preserving fish carcasses to minimize postmortem autolysis artifacts when a necropsy cannot be performed immediately. The purpose of this study was to qualitatively identify and score histologic postmortem changes in two species of freshwater fish (bluegill—Lepomis macrochirus; crappie—Pomoxis annularis), at varied time intervals and storage temperatures, to assess the histologic quality of collected samples. A pooled sample of 36 mix sex individuals of healthy bluegill and crappie were euthanized, stored either at room temperature, refrigerated at 4 °C, or frozen at −20 °C, and then necropsied at 0, 4, 24, and 48 h intervals. Histologic specimens were evaluated by light microscopy. Data showed that immediate harvesting of fresh samples provides the best quality and refrigeration would be the preferred method of storage if sample collection had to be delayed for up to 24 h. When sample collection must be delayed more than 24 h, the preferred method of storage to minimize autolysis artifacts is freezing if evaluation of the gastrointestinal tract is most important, or refrigeration if gill histology is most important. The gill arch, intestinal tract, followed by the liver and kidney were the most sensitive organs to autolysis.