Scholarship & Creativity
Findings on trout movement could improve fisheries management
A U-M-led scientific team has released new findings that may benefit ongoing efforts to restore lake trout populations in the Great Lakes.
In a forthcoming article in the Journal of Great Lakes Research, the School of Natural Resources and Environment's Sara Adlerstein and her co-authors report that higher proportions of lake trout marked with coded wire tags (CWTs) appear to move out of release areas in Lake Huron than previously thought.
Accurately tracking fish movement in and out of areas where they are released enables fisheries managers to gauge the success of restoration programs and to set management regulations for the recreational fishing industry, a major economic contributor to the regional economy.
"Our research results improve current understanding of lake trout movement from release to recovery areas, and provide detailed information on fish spatial distributions as well as temporal movements," Adlerstein explains. "This information is important in management models that impact decisions on stocking and regulations."
In 1985, lake trout stocking experiments using CWTs were initiated in Lake Huron. In 1992, fisheries experts began to study fish movement patterns, growth, survival and reproductive success. Approximately 1-2 million lake trout, 20 percent of which are marked with CWTs, are stocked in U.S. waters annually.
In addition to Adlerstein, the co-authors of "Lake Trout Movements in U.S. Waters of Lake Huron Interpreted from Coded Wire Tag Recoveries in Recreational Fisheries" include Edward Rutherford of the School of Natural Resources and Environment's Institute for Fisheries Research; John Clevenger, James E. Johnson and David Clapp of the Michigan Department of Natural Resources; and Aaron Woldt of the U.S. Fish and Wildlife Service.
Two U-M scholars have found that counties with universities were far more likely to have more botanical species reported in them than adjacent counties because they have a disproportionate share of botanists, who are likely to pay more attention to the plants in their local environment.
The study, which was published last year in the Journal of Biogeography, was conducted by Daniel Moerman, professor emeritus of Anthropology at U-M-Dearborn, and George Estabrook, professor of Botany at the Ann Arbor campus.
The researchers compared data from more than 30 areas of the country with major universities, measuring the botanical richness of the county housing the university with that of its neighboring counties. "In almost every case, there were more species reported in the university county than in its neighbors," Moerman and Estabrook say.
They considered a range of possible explanations, including the notion "that somehow, universities were situated in counties particularly well-endowed with botanical resources." The data were drawn from universities across the country, established more than 200 years, and almost certainly located where they are because of political and economic pressures, which made that explanation unlikely.
Other possible explanations were also considered, including the idea that university communities attract more visitors from other regions who might bring plant material with them. There were not enough data to make the case.
The results have wider implications for other sciences. "Ecologists must be aware that numerical data that appear very solid, collected over many decades, may represent not only the qualities of 'nature' but also something of the collectors of the data," according to Moerman and Estabrook.
Why 'wanting' and 'liking' something simultaneously is overwhelming
Wanting and liking are separate urges controlled by different brain circuits, and when combined at once the impact on the brain is especially powerful, according to University researchers.
The study reports that the brain divides wanting and liking into separate circuits for the same sweet reward. Natural heroin-like chemicals (opioids) in a few brain pleasure hotspots make individuals want to eat more of a tasty sweet food, and make them like its sweet taste more when they eat it, the study says. The same thing happens with addictions to drugs, sex, gambling and other pursuits involving brain reward circuits. The research is featured in the Journal of Neuroscience.
Psychology researchers Kyle Smith and Kent Berridge show that two different brain circuits carry out the wanting and liking for the sweet reward, even when both are triggered in the same brain pleasure hotspots.
"We typically want what we like, and like what we want," Smith says. "But these results suggest that wanting and liking are processed by distinct brain circuits and may not always go hand-in-hand."
Experimenters put an opioid drug (Damgo) into a pleasure hotspot in the brains of ratsin the front base of the brainusing a painless microinjection technique to deliver tiny chemical droplets to the brain target without disturbing the rats.
The opioid made the rats want to eat three times more food than normal, and to show double the normal number of liking expressions when they tasted the sugar. Liking expressions involve positive facial lip licking behaviors seen in rats, monkeys, apes and human infants.
To turn off a particular brain circuit, the experimenters simultaneously made another microinjection of an opioid-suppressing chemicalin a different pleasure hotspot of the brain in some rats.
Organizations benefit by hiring minorities
A new study suggests mainstream environmental organizations, which have been criticized over the last 15 years for lacking racial diversity, may be passing over qualified minority candidates who are interested in working for these nonprofits and have realistic salary expectations.
"The notion that minorities do not want to work for environmental organizations and demand high salaries which preclude them from being hired is a myth," says Dorceta Taylor, associate professor at the School of Natural Resources and Environment (SNRE).
Between 2004 and 2006, minorities constituted only 14.6 percent of the staff at mainstream environmental organizations, and 35 percent of those groups indicated they had no non-whites on their payrolls at all.
Between October 2003 and May 2005, Taylor conducted a national survey of college students in five life-sciences fields (biological sciences, forestry, natural resource management, agricultural sciences, and environment sciences), a physical science field, an engineering field and two social science groups.
She investigated the students' willingness upon graduation to work in five types of institutions (academia, governmental agencies, for-profit corporations, environmental organizations and other nonprofits) and asked about the minimum salaries they were willing to accept.
Taylor's findings reveal that students had a strong sense of where they were willing to work, what kinds of jobs they considered ideal, and the amount of salary they could expect upon entering the work force.
She identified some racial and gender differences, however, that proved perplexing. Results indicate women have lower salary expectations than men, while minorities have higher expectations than whites. Yet, in reality, both women and minorities tend to earn less than white men.
Taylor's article appears in the February 2007 issue of BioScience.