Translation Series No.1211

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In a further paper Piggins (1958) treats Irish salmon smolt.
With the aid of tagging he ascertained the losses in the region of the
Burrishoàle fishery. A total of 5224 ' -fteh were tagged, of which almost
3100 were smolt, the remainder being parr. One hundred and fifty-six 6f,'
the tags recovered were found in the stomachs of predators.
' According to Piggins, herons are commonly found in the region
in question; These birds have no enlarged pyloric antrum and usually void
the tags within 12 hours. Five birds.examined had four tags in their
stomachs. In order to avoid making to4iigh an estimate of the losses, we
shall assumethat one heron had eaten on an average only two tagged salmon
during the months in question, namely . October to December, which would
amount to 200 fish for 100 bird.
. Of the frequently encountered mergansers 15 birds were.examined,
which contained eight tags. Since these are retained in the stomach for
lengthy periods, one can reckon that 150 mergansers had eaten only 80
tagged fish.
'Cormorants.are very common, but also have no enlarged pyloric
antrum. Although previously up te five smolt had been found per bird, no
tags could be found in 22 birds. We estimate the losses through cormorants •
therefore as only 20 tagged fish.
The pollack (Pollachius pollachius) enters in spring in large.
the estuaries of the Burrishoole region. In 94 pollacks only un-
numbers
marked fish were found On the 1st and 5th of May, whereas the tagged smolt
were first liberated on May 1, and 5. Of further fish examined six pollacks
contained 12 tags at the end of May. According to Piggins all Pollacks eat
gmolt and follow them intô the sea in June. Formerly more than 60 per-haul