An estimated 15,000-20,000 tonnes of herring has been found floating dead in Kolgrafafjorour, a small fjord in west Iceland.
This is the second mass fish death since an estimated 30,000 tonnes were found in December and January.
Jóhann Sigurjónsson, director general of the Icelandic Marine Research Institute (MRI) told World Fishing & Aquaculture that the total documented mortalities during these two events is of the order of size 10% of the mature stock.
The MRI has visited the site several times and Mr Sigurjónsson said, “It is now clear that low oxygen level caused the mass mortalities and the most likely cause is the entering of huge biomass of herring into a relatively small fjord inlet, where degradation of dead fish may also have contributed to the most recent event.
“The herring seeks 2-3°C seawater during the low-activity over-wintering phase, which may be one of the reasons why the fish was "trapped" inside the fjord. The situation is closely monitored by the MRI scientists, where one is also considering whether preventing measures may be possible. However, as time passes, the herring will leave the area for feeding and spawning and migrate out of the nearshore areas”, Mr Sigurjónsson told WF&A.
Around 7,000 tonnes is said to be laying on the shore and many more at the bottom of the fjord.
It has been reported that the herring will be left to decompose naturally. Tens of thousands of birds have been drawn to the site to feed, but there are fears the fish oil from the decaying herring might threaten these birds in the coming weeks and months.
