8.0 PROCESSING DIFFERENT SPECIES
8.1 HARVESTING LUMPFISH ROE
Lumpfish caviar technology described in this chapter may serve in many
respects as a guideline for processing other small size roes like carp,
bream, roach, pike, and white-fish.
Lumpfish fishing history started in the fifties as a small boat coastal
water fishery of fish congregating for spawning. Only the fish roe is
used as raw material for lumpfish cav-iar. It is one of the most popular
sturgeon-caviar substitutes. Attempts to make use of the fish carcasses
for bait, for meal or for human consumption have not enjoyed com-mercial
success. Fresh lumpfish fillets have found some limited use in Iceland
as an ex-otic specialty product. High water content and low protein
yield makes lumpfish an ex-pensive resource for fishmeal production.
Experiments to substitute lumpfish for herring in lobster traps and
for ground fish long lines were not successful. As a result millions
of pounds of lumpfish carcasses are discarded annually over shallow
water, which are often fishing grounds for crustaceans.
Initially, lumpfish were extensively harvested only in European waters.
With the de-mand growing the lumpfish fisheries have expanded throughout
Our knowledge of the biology of lumpfish and information on the strength
of stocks are insufficient to make long-term projections regarding the
sustainability of lumpfish fish-eries. Figure 8-1 shows world catches
by countries. The information compiled by Mr. E. Olafsson (Iceland)
shows a maximum production of over 6,000 tons of roes in 1987. The yearly
fluctuations reflect the demand-supply pressures in the marketplace.
Biologists speculate that a 10/000 ton sustainable world roe harvest
World Production of Lumpfish Roe 1971-90, Thousand
In the seventies Denmark was buying up to 60% and Germany
up to 25% of the total world production of heavy salted lumpfish roe.
Through the eighties this share fell to 25 and 5%. France, USA and other
countries are packing from 2 to 10% of the world's pro-duction. At the
same time Iceland's share of packed lumpfish caviar production grew
from 5% in 1970 to 60% in 1990. Canada's lumpfish caviar production
is only emerging in spite of the fact that Canada is the second largest
Lumpfish roe producer.
Lumpfish are harvested by gill nets which are placed in
fish migration pathways to the spawning ground. The smaller males often
pass through the large mesh. Because of their peculiar morphology the
fish are not strongly enmeshed, so fishermen pull the nets care-fully
so as not to lose the catch. Fishing depth varies and may exceed 50
meters. Nets are set at the bottom in fleets of five to ten nets each
up to 100 meters long. Net depth ('width') measures 10 to 16 meshes
of 11 inch mesh size.
Net fleets are moored with anchors and are checked at
least every other day. The entan-gled fish is usually alive. Ovaries
from dead fish are not used.. When using a gaff to pull the fish, care
must be taken not to damage the roe. The roe constitutes 15 to 30% of
the total fish body weight, which ranges from 2 to 7 kg. Fish length
is 35 to 60 cm.
The schools contain different year classes, which is difficult
to determine. It is observed that spawning takes place over the same
grounds in waves. The peak period of maturity differs greatly from area
to area and depends on water temperature. Knowledge of the behavioral
patterns of spawning schools is essential for obtaining best egg yields.
Fish-ing grounds are dispersed along a lengthy shoreline, which creates
difficulties for the processing logistics. Many fishermen, finding it
difficult to quickly transport fresh roe to larger processing sites,
are screening and heavily salting roe themselves. That is one of the
reasons why processing low salted caviar from fresh roe on the fishing
grounds is not yet widely implemented.
Ovaries are extracted as soon as the fish is onboard.
Slits are done from the tail end up-ward, leaving the anal end intact.
Unlike salmon ovaries, the lumpfish ovaries attach-ment to the body
is not strong enough to hold them when the fish is held up vertically
by the tail.
Ovaries are removed and first put into a flat mesh basket
to get rid of the excessive fluid released from the belly cavity. Then
any organs which are still attached to the ovaries are manually removed
and the ovary is put in a clean transportation container.
Containers should have a lid, be kept cool, and provide
for continuous drainage of ex-cessive fluid. Direct contact of ovaries
with ice is not recommended. Ovaries are trans-ported in layers not
exceeding 30 cm to reduce transportation stress. Stackable shallow boxes
with lids are preferred. Some grading by size and colour is advisable
as the ova-ries removed. Mature eggs are purple to reddish, immature
eggs range from green to grey.
As soon as possible, in any case, within 24 hours, the
chilled ovaries are screened in on-shore facilities manually, or using
machines. Screening of ovaries at high tempera-tures, screening immature
ovaries, or non fresh ovaries results in excessive breakage and lower
The eggs inside the ovaries are essentially sterile. This
means, that if they are not dam-aged during extraction and quickly rinsed
before screening in light (3 to 4%) brine to wash off slime and residuals
of blood, the lowest possible contamination with microor-ganisms is
Exposure of ovaries to direct sunlight causes substantial
quality losses. Fresh ovaries are elastic. Deteriorated ovaries become
soft and the eggs are easily squashed releasing milky egg yolk. Final
grading before screening is important to keep separate lots of dif-ferent
Overmature lumpfish eggs are said to have a thin outer
membrane. This may be of great advantage in obtaining the "melting"
mouthfeel, similar to the one of sturgeon eggs. Roe of this quality
should be slightly salted and packed for consumption without preliminary
heavy salting. Combined with grading by size and colour and dying in
grayish shades such a product may claim premium quality.