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Background and objectives Substance use behaviors have been identified as a risk factor that places juveniles at greater risk for engaging in delinquent behaviors and continual contact with the juvenile justice system. Currently, there is lack of research that explores comorbid factors associated with substance use, such as post-traumatic stress disorder (PTSD) symptoms, that could help identify youth who are at greatest risk. The aim of the present study was to examine if PTSD symptomology moderated the relationship between substance use disorder (SUD) symptoms and externalizing behaviors and commission of a violent crime; hypothesizing that risk would be heightened among youth with elevated SUD and PTSD symptomology compared to those with elevated SUD symptoms but lower PTSD symptoms. Method The study included 194 predominantly male (78.4%), non-White (74.2%) juvenile justice youth between the ages of 9-18 (M = 15.36). Youth provided responses to assess PTSD symptoms, SUD symptoms, and externalizing behaviors. Commission of a violent crime was based on parole officer report. Results Findings indicated that SUD symptomology was associated with greater externalizing behaviors at high levels of PTSD symptomology. At low levels of PTSD symptomology, SUD symptoms were inversely associated with externalizing behaviors. An interactive relationship was not observed for commission of violent crimes. Conclusions Findings suggest that the association between SUD symptoms and externalizing behaviors among juvenile offenders may be best explained by the presence of PTSD symptomology. Scientific significance Addressing PTSD rather than SUD symptoms may be a better target for reducing risk for externalizing behaviors among this population of youth (Am J Addict 2019;28:29-35).

Walleyes Sander vitreus are extensively cultured across Michigan, with highly variable success resulting in substantial differences in growth and survival. The present study was undertaken in 2005 and 2006 to determine the relationship between abiotic components (temperature, dissolved oxygen, and nutrient levels), prey (zooplankton and benthic macroinvertebrate) availability, and stocking density in ponds in the Lower Peninsula of Michigan and the growth and survival of walleyes in these ponds. Besides fertilization of some of the ponds, there was no management of the ponds until harvest. Ponds were grouped by similarity of abiotic and biotic factors. Correlations among walleye length, weight, and stocking density, as well as between walleye percent survival and stocking density, provided contradictory results between years. Walleye growth and survival were correlated with planktonic prey densities and nutrient levels. Although these interactions among abiotic variables, prey availability, and w...

The high variability in reported lengths of larval yellow perch Perca flavescens at hatching, dietary shift, and morphometric transformation may be partly caused by shrinkage that occurs after preservation. Larval yellow perch were captured, randomly assigned to one of six preservative treatments (100%, 95%, 80%, and 50% ethyl alcohol and 5% and 10% formalin), and measured (before preservation) for total length (TL). Larval yellow perch total lengths were then recorded on days 1, 7, 14, and 21 after storage in each of the six preservatives. Significant reductions in TL (11.5–14.3%) occurred during the first 24 h after fixation and larvae continued to contract at a lesser rate through day 7 in all four ethyl alcohol treatments. Total length reductions of up to 2.5% also occurred during the first 24 h in each formalin concentration. Our findings report the total length reductions of larval yellow perch at a length range used by some biologists when indexing year-class strength and during studies of...

We sought to determine if abundance of larval yellow perch Perca flavescens could predict abundance of age-0 juvenile perch in late summer. Yellow perch larvae and juveniles were sampled from six eastern South Dakota glacial lakes in 1997. The number of age-0 yellow perch caught per seine haul in late summer was positively related to larval abundance in late May and early June (N = 6, r = 0.90, P = 0.01). When data collected from two eastern South Dakota lakes in 1995 and 1996 were added to this assessment, we also found a significant positive relation (N = 10, r = 0.88, P = 0.0009). Thus, biologists in eastern South Dakota can use larval yellow perch abundance as an early indicator to determine which water bodies are likely to have a weak naturally produced year-class and then can evaluate the success of fingerling perch stocking strategies.