Met
hylmercury is known to bioaccumulate and bioma
gnify up t
he marine food c
hain. Fis
h from
hi
gh levels of t
he marine food c
hain may contain relatively
hi
gh concentrations of mercury, and most (>70 % ) of t
he mercury found in muscle is met
hylmercury. In aquaculture, marine protein (mainly fis
hmeal) is t
he dominant source of met
hylmercury, and t
his raises some concern wit
h re
gards to fis
h welfare and consumer safety. A dietary exposure study, includin
g a depuration period, was carried out in order to study t
he accumulation and elimination of met
hylmercury in Atlantic cod (
Gadus morhua L.), and to estimate t
he transfer of met
hylmercury from feed to fis
h. Fis
h were sampled t
hrou
ghout a t
hree mont
h exposure period and a t
hree mont
h depuration period. Muscle samples were fractionated into a protein and a lipid fraction by lipid extraction usin
g met
hanol and c
hloroform. Mercury and met
hylmercury were determined by inductively coupled plasma mass spectrometry (ICPMS) and
gas c
hromato
grap
hy-inductively coupled plasma mass spectrometry (GC-ICPMS), respectively. A continuous accumulation of met
hylmercury, after a la
g period of 10 days, was observed in muscle tissue durin
g t
he t
hree mont
hs exposure to met
hylmercury (0.95 ± 0.03 μ
g H
g/
g feed,
n = 6). After t
hree mont
hs, t
he final concentration in muscle was 0.38 ± 0.04 μ
g H
g/
g ww (
n = 6), w
here met
hylmercury constituted 90–95 % of t
he mercury present. T
he elimination of met
hylmercury from muscle was slow and incomplete (wit
hin t
he t
hree mont
hs of depuration) wit
h an estimated elimination
half-life
href=""/science?_ob=MathURL&_method=retrieve&_udi=B6T4G-4NT9G7M-1&_mathId=mml8&_user=10&_cdi=4974&_rdoc=10&_acct=C000050221&_version=1&_userid=10&md5=982cec113ae2684e92cb47ba69801bc0"" title=""Click to view the MathML source"">(t1/2) of 377 days. T
he transfer of met
hylmercury from feed to Atlantic cod, described by t
he estimated absorption efficiency, was 38 % . In muscle more t
han 99 % of t
he mercury was found in t
he protein fraction. T
hese results su
ggest t
hat Atlantic cod readily takes up dietary met
hylmercury, w
hic
h is efficiently accumulated into muscle, w
here it is incorporated into lar
ger peptides or proteins. Comparable results were found for Atlantic salmon (
Salmo salar L.). After t
hree mont
hs of exposure to dietary met
hylmercury t
he final concentration in muscle was 0.33 ± 0.01 μ
g H
g/
g ww (
n = 3), w
here nearly all (>99 % ) mercury was found in t
he protein fraction. T
his furt
her supports t
hat met
hylmercury is accumulated in fis
h muscle, w
here it is incorporated into lar
ger peptides or proteins.