Egg-thiamine Status and Occurrence of Early Mortality Syndrome (EMS) in Atlantic Salmon from the St. Marys River, Michigan

Five year trends in the egg-thiamine status of Atlantic salmon from the St. Marys River, Michigan

“…The ED50s were 1.03, 1.57 and 2.38 nmol/g egg for Chinook salmon O. tshawytscha, lake trout S. namaycush, and coho salmon O. kisutch, respectively. The ED50 for the St. Marys River Atlantic salmon population was approximately 1.0 nmol/g egg (Werner et al, 2006). This result is similar to those found by other groups working with Atlantic salmon (Marcqenski and Brown, 1997;Amcoff et al, 1998, Fisher et al, 1998.…”

“…The linkage between eggthiamine levels and the resulting prevalence of EMS for this population have been previously published (Werner et al, 2006). Here we present the five-year trend in egg-thiamine status for this unique population of Atlantic salmon.…”

“…The detailed reasons for this lower threshold are unclear. As stated previously, the St. Marys River population of Atlantic salmon has been shown to be susceptible to the effects of EMS due to low levels of eggthiamine (Werner et al, 2006).…”

“…The RP-SPE method for thiamine analysis of fish eggs was used to measure the egg-concentration of phosphorylated thiamine, nonphosphorylated thiamine, and total thiamine. The method used was essentially that of Zajicek et al (2005) but with several published modifications (Werner et al, 2006). This technique relies on liquid phase extraction of thiamine containing compounds from disposable solid-phase columns followed by oxidation and conversion of the eluted compounds to a fluorescent thiochrome.…”

“…Approximately 1 g of this sample was subsequently homogenized for thiamine analysis as previously described (Werner et al, 2006). The RP-SPE method for thiamine analysis of fish eggs was used to measure the egg-concentration of phosphorylated thiamine, nonphosphorylated thiamine, and total thiamine.…”