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Operating methods which belong to this
remove entrails when dressing salmon
category include the use of vacuum suction to
(mainly for the fresh/frozen market), and sex
sorters used for roe herring processing (see Section 4.4.2). New developments which
would allow the removal of entrails from salmon gutting machines by vacuum suction (i.e.
without the entrails coming into contact with water) are being or will be marketed in the
near future (communications with Coastline Equipment Inc. and Ryco Incorporated of
Seattle, WA).
As discussed in Section 4.4.2, the use of herring sex sorters results in reduced water
consumption and wastewater contaminant loading. These sorters have a high capital
cost and are Iabour intensive, as they require manual placement and alignment of the fish,
although they reduce the Iabour requirements for freezing, frozen storage, thawing, and
breaking. Also, sex sorters are not 100 % accurate, and a certain loss of roe due to
miss-identification of females as male herring must be taken into account in an economic
analysis. Howeveri the economics of sex sorting might further improve if the sorters are
used in conjunction with automatic feeders, which could also be used to supply automatic
popping machines (see Section 4.4.3). As the same machine could be used for two
different purposes (feeding of sex sorters, and automatic popping machines), the savings
of the labour cost would accelerate the amortization of the feeders.
The type of processing carried out at a plant also substantially affects how seasonal the
operation is, which directly affects the time required for amortizing equipment purchased
for in-house modifications or wastewater treatment. For example, some facilities
processing farmed salmon operate year round, compared to wild salmon which is
processed mainly from July through August. Processing plants handling farmed salmon
can make use of, and amortize, their equipment year-round, whereas ,plants processing
wild salmon are restricted to a few months. Because of the seasonal nature of wild
salmon processing, most plants involved in this type of operation also process roe herring
to make use of unused capacities during the spring. In additidn, to adequately treat all
wastewater generated at a fish processing plant, any wastewater treatment system would
have to be designed for a relatively large flow which the processing plant may only
discharge on few days during the year. This is caused by the tremendous fluctuations
in throughput during the processing seasons. To illustrate this point, Figure 7.2 shows
the monthly landings at three plants as a fraction of the maximum monthly landings at
each facility in 1993. The plants had the following characteristics:
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