We evaluated the sensitivity of larval sea lampreys Petromyzon marinus to the lampricide 3‐trifluoromethyl‐4‐nitrophenol (TFM) in a series of toxicity tests in spring and summer. Although noted previously, the seasonal variation in sensitivity to TFM had never been tested as a means of reducing TFM usage in stream treatments. A preliminary study consisted of three spring and four summer static toxicity tests conducted at 12°C. A more comprehensive study consisted of 12 spring and summer paired flow‐through toxicity tests conducted both at seasonal water temperatures and at 12°C. The sensitivity of larval sea lampreys to TFM was greater in spring than in summer. The preliminary static toxicity tests indicated that the concentration of TFM needed to kill larval sea lampreys in spring (May and June) was about one‐half that required in summer (August); the concentrations lethal to 50% and 99.9% of the test animals (the LC50 and LC99.9 values) were less in spring than in summer. Analysis of variance of the flow‐through toxicity data indicated that season significantly affected both the LC50 and LC99.9 values. For all 12 paired flow‐through toxicity tests, the spring LC50 and LC99.9 values were less than the corresponding summer values. For 9 of the 12 paired flow‐through toxicity tests, the dose–response toxicity lines were parallel and allowed statistical comparison of the LC50 values. The spring LC50 values were significantly lower than the summer values in eight of the nine tests. Verification of a seasonal variation in the sensitivity of larval sea lampreys to TFM will allow inclusion of this factor in the selection model currently used by both the U.S. Fish and Wildlife Service and the Department of Fisheries and Oceans–Canada to schedule lampricide stream treatments.

The authors developed a package, LW1949, for use with the statistical software R to automatically carry out the manual steps of Litchfield and Wilcoxon's method of evaluating dose-effect experiments. The LW1949 package consistently finds the best fitting dose-effect relation by minimizing the chi-squared statistic of the observed and expected number of affected individuals and substantially speeds up the line-fitting process and other calculations that Litchfield and Wilcoxon originally carried out by hand. Environ Toxicol Chem 2016;35:3058-3061. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

Two hundred one American toads (Bufo americanus) from northern Michigan were examined for blood trypanosomes. Three species, Trypanosoma bufophiebotomi, T. schmidti-like sp. and T. pseudopodia, had prevalences of 27, 16 and 1%, respectively. Cross experimental inoculations showed that T. bufophlebotonzi from toads is not the same as T. ranarum found in frogs of the family Ranidae of this region.

Barrier dams, traps, and lampricides are the techniques currently used by the Great Lakes Fishery Commission to control sea lampreys {Petromyzon marinug) in the Great Lakes. To augment these control techniques, a sterile-male-release research program was initiated at the Lake Huron Biological Station. Male sea lampreys were sterilized by intraperitoneal injection of the chemical sterilant P,P-bis(1-aziridinyl)-Nmethylphosphinothioic amide (bisazir). An analytical method was needed to quantitate the concentration of bisazir in water and to routinely verify that bisazir (>25 μg/L) does not persist in the treated effluent discharged from the sterilization facility to Lake Huron. A rapid, accurate, and sensitive liquid chromatographic (LC) method was developed for determining bisazir in water. Bisazir was dissolved in Lake Huron water; extracted and concentrated on a C18 solid-phase extraction column; eluted with methanol; and quantitated by reversed-phase LC using a Cis column, amobile phase of 70% water and 30% methanol (v/v), and UV detection (205 nm). Bisazir retention time was 7-8 min; total run time was about 20 min. Method detection limit for bisazir dissolved in Lake Huron water was about 15 μg/L. Recovery from Lake Huron water fortified with bisazir at 100 μg/L was 94% (95% confidence interval, 90.2-98.2%).