Zooplankton as a
bio-resource for fish feed and industrial raw material
Aquaflow Technical Leaflet 2002-100
European Network for the Dissemination of Aquaculture
RTD Information (Q5CA-2000-30105) and previously FAIR-3837, URL: http://www.aquaflow.org/
This strategic Norwegian research programme examines
the feasibility of using organisms low in the food web, such as the copepod Calanus
finmarchicus, for fish feed and other industrial raw materials. There is
a growing demand for marine bio-resources, and the aquaculture industry is
already facing limiting resources for fish feed especially regarding marine
oils. Zooplankton is an excellent resource for marine oils with high content
of n-3 fatty acids as well as for proteins, pigments, wax esters and chitin.
C. finmarchicus represents
an enormous resource that is not exploited today.
The main objective of the “CALANUS” programme is
to clarify possibilities, constraints and consequences of large-scale
exploitation of marine zooplankton resources. Zooplankton serves as food for
important fish stocks, which brings up a strong management and political
dimension. Potential interactions with fisheries as well as ecological
aspects therefore have a main focus in the research. CALANUS includes
research on resource biology and modelling, harvesting technology, handling
and preservation of harvested material, refinement of raw material,
evaluation of use for fish feed and a number of by-products as well as
studies of socio-economic effects of zooplankton fisheries.
Estimations of egg production and viability indicate
that copepods in fjords are normally not food limited. This may have
implications for a future management practice. New estimates of the annual
production of C. finmarchicus by
means of a coupled 3D hydrodynamic/ecological model are 90 million tons wet
weight for the Norwegian Sea. Numerical modelling suggests that production
of C. finmarchicus is not affected
by fishing on over-wintering populations as long as the population is not
brought below a critical limit. Both traditional rigged beam trawls as well
as new developed self-spreading trawl nets have proved efficient in catching
C. finmarchicus concentrating near
the surface, although occurrence of predating jellyfish has been found to
hamper significantly the efficiency of the nets. Another trawl design, based
on fixing a calanus trawl belly to the forepart of an ordinary Otter trawl,
has proved efficient in deepwater catching conditions in late autumn.
Catches of 65 kg Cal./h have been achieved at 370 m depth at Salten near Bodø
in November with this net. The resource studies combined with catching
experiments have shown that the catching availability of "deepwater
Calanus" seems to be good during autumn with sufficient concentrations
at 100-250m above the bottom. Frozen zooplankton catches were successfully
dried by low temperature fluid bed drying to produce high quality powder for
further refinement. The aim is to use relatively crude products for fish
feed where biopolymers such as alginate and chitosan will be explored as
binders. Testing of fish feeds based on C.
finmarchicus are planned.
This 5-year programme
(2001-2005) is funded by the Research Council of Norway with significant
contribution of the Norwegian University of Science and Technology. SINTEF
Fisheries and aquaculture in Trondheim is a major co-operative partner.
For more information:
VADSTEIN Olav
Trondhjem Biological Station - Norwegian University of Science and
Technology
N-7491 Trondheim
Norway
Phone : +47-73590204
Fax : +47-73591597