Fróðskaparrit - 01.07.2004, Blaðsíða 124

122
MERCURY 1N THE FAROE ISLANDS — A REVIEW OF AVAILABLE DATA
er (see also Caurant et al., 1994). The high-
est recorded mean liver mercury concentra-
tions was detected in the Hvalba 1977
grind3, at 280 ± 100 mg/kg ww (n=8)
(Juelshamn et al., 1987). The inter and in-
tracellular distribution of mercury in long-
finned pilot whales muscle, liver and kid-
ney tissue was described by autometallo-
graphic tracing (Stoltenberg et al., 2003).
A large, but variable part of the total mer-
cury in pilot whale is present as methylated
mercury. According to the study by Juels-
hamn et al., (1987) involving pilot whales
from Hvalba in 1977 and Hvannasundi in
March 1978, an average of 48% and 64% of
the total mercury in the meat was methylat-
ed mercury in the two samples respectively.
The range however, was quite wide, with
the lowest values in the Hvannasund sam-
ples at 24% and the highest at 86%. These
86% equalled 1,72 mg/kg of methylated
mercury and this concentration was found
in the largest individual of 16 skinn.
The skinn value is a traditional measure
of the size of the whale in edible amounts
of meat and blubber, where one skinn is ap-
prox. equal to 34 kg of meat and 38 kg of
blubber (Bloch and Zachariassen, 1989).
The skinn value is also used when de-
picting the mean pod mercury concentra-
tion as in Fig. 15, because this gives the
possibility to calculate a pod mercury aver-
age which is then unrelated to possible ab-
normal distribution of females and males
and young and adults in the pod. By intro-
ducing a correction factor based on the
skinn values mass weighed mercury pod
means may be calculated. The calculation
is done by multiplying the group mercury
means with the average percent of the total
pod mass the particular group normally
represents. For the adults males this per-
centage was found to be 23% in the large
1986-88 study, and similarly, the mass
made up of adult females was on average
42%, and the one comprised of juveniles is
32 % (Bloch et ai, 1993b). The overall
mean adult male and female muscle mer-
cury concentration (mean of figures pre-
sented in Table 15) in recent years was 2,4
and 2,3 respectively, with the mean concen-
tration in the young at 1,3 mg/kg. Seen in a
larger time perspective (Fig. 15) these con-
centrations do not appear to be markedly
lower than in earlier analyses. However, a
pod mean of 3 mg/kg as in the Hvalba 1977
study has not been recorded since, and the
reason may be found in the sampling, be-
cause the Hvalba sample size was only 10
individuals of unknown size, so if these
were solely adults, then a mean of 3 mg/kg
would be consistent with later samples for
instance those of Tórshavn Sep. 1997 and
Nov. 1997 as well as Tórshavn Sep’2002.
White-sided dolphin
In the Faroes, white-sided dolphin, Lage-
norhynchus acutus, schools are occasional-
ly taken for food in the same manner as the
pilot whales. The average annual number of
white-sided dolphins taken during drive
hunts in the last decade is 370 individuals
(Bloch, 2004) with some years no catch at
all, as in 1999, and with peak years in be-
tween, with a maximum in 2002 where 774
white-sided dolphins were taken.
Few analyses of environmental pollu-
tants including mercury have been done on