Cultivating Palmaria palmata - Bord Iascaigh Mhara

usually less for nets than for droppers, but the total yield per metre of longline was higher, especially when
multiple harvests could be taken.
On the basis of our trials of Palmaria ongrowth at sea, which have been conducted over 3 years at four different
sites, the following conclusions can be drawn:
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Site of cultivation: The choice of site is critical for successful grow-out of Palmaria at sea. Strangford
Lough and Ard Bay seem to provide the right habitat, probably because strong currents ensure good
water exchange and favourable water temperatures. Although the site at New Quay has a relatively high
current flow, Palmaria production was not satisfactory. Palmaria trials have been conducted at RWB in
all 3 years of the project, but it is evident that this site is not suitable for Palmaria cultivation. The
sheltered position of the site means that water currents are relatively weak, so that summer water
temperatures can exceed the optimum for Palmaria, and the potential for fouling also seems to be high.
It was shown, however, that the site is excellent for the cultivation of several kelp species.
Time of deployment: The best time for deployment of Palmaria sporelings is late autumn/early winter.
Before December, the sporelings reach a size (approx 5 cm) that enables them to compete with the
fast-growing fouling algae, which start to settle from late January onwards. Rapid growth of Palmaria is
observed in early spring until early summer
Length of cultivation: The fastest growth of Palmaria is observed from early spring until early
summer. The results indicate that Palmaria fronds of the highest quality are harvestable in early-mid
spring. The material can quickly deteriorate, due mainly to settlement of fouling organisms, grazing,
bleaching of fronds due to high light in late spring/summer, and detachment or dislodgement of fronds
when they reach lengths of over 40 cm and weights of over 100 g. An ongrowth time of 5 months from
November until April seems to be optimal.
In conclusion, despite some encouraging results in the project, it has not been possible – between 2008 and mid
2011- to demonstrate year-on-year a consistently successful culture methodology for the sequence of Palmaria
sporulation – settlement on string – sea deployment – grow-out to harvest.