Use of spat collectors to enhance supply of seed for bottom culture of blue mussels Mytilus edulis i

1
Use of spat collectors to enhance supply of seed
for bottom culture of blue mussels (Mytilus
edulis) in the Netherlands Pauline Kamermans,
Emiel Brummelhuis, Aad Smaal Netherlands
Institute for Fisheries Research (RIVO), Centre
for Shellfish Research, P.O. Box 77, 4400 AB
Yerseke, The Netherlands, pauline_at_rivo.wag-ur.nl
Introduction In the Netherlands, the target
mussel production is 100 106 kg per year. To
reach this, the growers depend on 65 106 kg
seed, which they fish from wild beds. However,
spatfall shows large variations between years
(see figure). The aim of the present 2-year study
is to determine the technical and economical
feasibility to produce mussel seed for bottom
culture with spat collectors. Results of year 1
are presented.
Set-up
Effect of location in estuary The number of spat
collected on the water column set-up showed large
variability between the four test locations. SP
and NZ collected most spat.
water column set-up with 4 types of collector
rope (NZNew Zealand, SCScotland, SPSpain,
FRFriesland)
tidal flat set-ups with 5 types of collector rope
(NZ, SC, SP, FR, RORon Oorschot), 2 types of net
(SWshadow, VObird), and straw (ST), mussel
(MU)- and cockle shells (CO)
high
40 cm
low
0.75 cm
Effect of depth Generally better spatfall on
upper part of ropes.
Effect of water column or tidal flat At the tidal
flat test sites, the amount of spat collected per
50 cm rope, 1500 cm2 net, or 1 kg straw, or
mussel-, or cockle shell is lower than with the
water column set-up.

• Conclusions
• Spatfall on suspended ropes is best on SP.
  Spatfall on the tidal flat is best on shells. No
  effect of heigth above bottom was found. Labour
  extensive bottom substrates need further
  investigation.
• It is estmated that an area of 70 ha (175 acres)
  is needed for spat production of 2 106 kg with
  the best rope collector (SP in Wadden Sea). This
  clean seed can be an important addition to the
  catch from wild beds.

Acknowledgements This project is funded by the
Dutch Fish Board and the Province of Zeeland.