Undersøkelser i forbindelse med prøvehøsting av stortare i Nord-Trøndelag 2012
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Date
2012-12-15Metadata
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- Fisken og havet (1958- ) [700]
Abstract
The Institute of Marine Research surveyed the kelp vegetation, before and after kelp (Laminaria hyperborea)
harvesting in Nord-Trøndelag in June and August 2012. Survey stations included both kelp harvested areas
(harvested in 2010, 2011 and 2012) and nearby reference areas, and was performed by underwater video. In
addition, kelp plants were collected for measurements of plant length, diameter, weight, age and epiphytes.
Based on these observations the state of the kelp forest was considered to be healthy, with an average of 27 kg
kelp biomass per m2 prior to harvesting and moderate densities of sea urchins. The recovery of kelp vegetation
on fields harvested in 2010 and 2011 is ongoing, and the kelp coverage in harvested areas were 90% (21 months
after the 2010 harvesting)) and 74% (11 months after the 2011 harvesting) in June 2012. The average length of
the recovering generation of kelp plants was in June 2012 around 17% (11 months after the 2011 harvesting) and
28% (21 months after the 2010 harvesting) of the average kelp plant sizes prior to harvesting. The density of sea urchins was generally low and grazing effects on recovering kelp plants appeared negligible. The harvested kelp
crop in Nord-Trøndelag in 2012 was 14.901 tonnes, and estimated to be around 5,5 % of the standing kelp stock
on the 8 fields earmarked for kelp harvesting this year.