FAQ – Lice skirts
Frequently asked questions and answers about lice skirts.
How long must the lice skirts be?
Skirts are manufactured to the lengths the customer wants. The skirt can be produced in a length that goes around the entire cage or you can have two or more skirts around the cage. For steel systems one can choose to encapsulate the individual cage or the entire cage, the length of the skirts is determined in consultation with the customer. FiiZK delivers skirts with overlap with or without closure and tubular skirts.
How deep must the lice skirts be?
FiiZK produces skirts at standard depths of 6 or 9 meters. We supply skirts in other depths on request. The site’s depth, flow, oxygen conditions, freshwater flow, cage and mesh type are factors that determine the depth of the skirt. FiiZK has delivered skirts from 3 to 15 meters depth.
How much flow do I need at the top?
Our lice skirts have a flow channel of 160x50mm. This gives a buoyancy of 8 kg per meter. A skirt with flow and 4 kg download / m is approximately self-flowing depending on the current flow conditions. Floating element at the top of the skirt facilitates the fitting on the location. FiiZK has also developed a concept for mounting skirts without flow.
How much down-soldering should the skirts have?
In order for the skirt to hang straight down and not bow it is necessary to down-soldering the skirt. FiiZK has 4 kg download / m as a standard. We use steel balls spun with polypropylene and polyethylene. The advantage of this in front of the chain, is that spun-down down-soldering gives fewer wear points while being more compact and flexible than the chain. We also have 2 and 6 kg in stock, other variants can be specially ordered.
Do you recommend splash edge to prevent waves from breaking over the float?
Splash edge is used by some breeders who find that waves wash over the float / skirt and into the cage. FiiZK’s lace skirt can be supplied with a splash edge to reduce the impact of water from waves. Our recommendation for a conventional gusset attached to the skirt is a height of 50 cm with slots for groove attachment. FiiZK recommends using a splash edge when installing the skirt on the inside of the float ring.
Does the lice skirt affects the oxygen level in the cage?
The lace skirt project showed that the lice skirt reduces the water exchange in the cage. The oxygen level is lower within the shielded volume, but the fish often stands deeper if it has available space under the skirt. The fact that the fish is deeper is in principle positive and helps to prevent lice onset. This can be a challenge during periods of low oxygen levels. The lace skirt can be raised with the lift curtain system to increase water exchange in the cage. FiiZK has tested new oxygen extractors for use with lace skirts and in closed cages. These provide so-called UltraFine Bubbles (UFB) that are so small that they do not have buoyancy. This results in better water dissolution and reduced oxygen consumption. The technology has been used in the aquaculture industry in Canada with good results.
How strong flow conditions does the skirt withstand?
Through model experiments in the Flumetanken in Hirtshals, analyzes carried out by Aquastructures and user experiences, FiiZK has experienced of what opportunities and challenges can provide exposed localities. We can see that the skirts start to creep upwards when the current exceeds 80cm / s. Deeper skirts are often more affected by this than shallower skirts. FiiZK has test reports available that show how flow conditions affects lice skirts.
How long is the delivery time?
Skirts should be fitted before the fish is released. All skirts are sewn by order and in the periods before release we often have great progress. It is recommended to be out early with mooring analysis and subsequent booking. Delivery time can vary from 2-8 weeks depending on when in the year the order is placed.
Should the lice skirt be mounted on the outside or the inside of the float ring?
FiiZK recommends that skirts should be mounted on the inside of the float ring, but they can also be placed externally. For interior mounting it is easiest to do this before mounting the net. The skirt stands better in the sea when supported by the net. It is easier to keep the inside of the skirt free of growth when mounted on the inside. When you wash your net, you also wash your skirt. With external mounting you often get gnawing from the main foot attachments and there is a greater chance of getting skirt in the propeller.
FiiZK has documentation on the release of lace skirts that can be helpful in preparing farmers for the use of lice skirts.
How often does the skirt need to be washed?
When the skirts are mounted inside of the float ring, the skirt is cleaned when flushing the net. You wash the skirts as often as you wash the net. Externally, the skirts can be washed in the sea by flushing with a RONC. The frequency of washing is determined by how exposed you are to growth, some breeders do not wash the skirts externally during a release. When the skirts are picked up by the sea, they can be laid out for drying or they can be sent to the net laundry for cleaning.
How long life time does the skirt have?
The life of the skirt is dependent on several factors: Power, where the cage is exposed, and whether daily maintenance is followed up. Similarly, of course, proper use and maintenance must be assumed. We have customers who have used our skirts for up to 3 years in a row, more and less without service and repairs, but it should also be admitted that we have customers who use them in one season and need to repair them.
How does it work with clean-fish and lice skirt?
Most of the time, none of the remedies for salmon lice work alone, but a combination of good work. Many of FiiZK’s customers have the best experience with the combination of lice skirts, cleaning fish and good cleaning. Sonar testing shows that fish are often deeper in cages with skirts. The location of the clean fish shed, should be adapted based on where the fish mainly resides.
What do I Find in the technical documentation?
Lice skirts are categorized as optional, and Aquastructures has verified that they meet the requirements of NYTEK regulations and NS9415: 2009. Drawings, calculations and execution have been reviewed. The accessories have been evaluated and documented for use within the specified limits in the Aquastructures technical reports. These reports help to form the basis for mooring analyzes in connection with the use of skirts.
FHF’s project “Permanent Skirts for Reducing Lice Loss on Salmon” answers a number of questions related to skirt deformation and mooring forces, hydrodynamics of skirt use, oxygen and fish behavior, lice suppression and fish welfare. Reports for project number 900711 are published on www.fhf.no For information on current and wave’s influence on lice skirts, see model experiments carried out through «Strategy Salmon lice 2017: What happens with lice skirts in currents and waves – experience sharing seminar and model experiments in Hirtshals» Report number 901405 is published on www.fhf.no
Does FiiZK have an overview of old orders?
As a FiiZK customer, you gain access to FiiZK’s customer service. Here you can log in and find all information about projects provided by FiiZK. Customer service contains all information relevant to your order such as drawings, user manuals, data sheets and reports.
Why should I choose FiiZK as a supplier?
FiiZK holds a leading role in the industry in the research and development of tarpaulin products for the aquaculture industry. During the period 2010-2015, FiiZK has been involved in research projects worth more than NOK 40 million. No other supplier can show the same activity. This means that FiiZK possesses a unique expertise in the development, production and use of lace skirts. FiiZK is the owner of the project Lice skirt – permanent skirt for reducing salmon lice. The project ran from 2012 until March 2015. The main objective of the project was to document the effect of Lice skirts in relation to reducing lice premiums. Reports for project number 900711 are published on www.fhf.no
FiiZK is committed to creating jobs along the coast. All production takes place in our factories at Lundamo and Fosen in Trøndelag, Norway. FiiZK is a member of the NCE AquaTech Cluster and a partner in ctrlAQUA. FiiZK is also an approved learning company.
Does FiiZK have any references I can contact?
FiiZK has references that can be provided on request in all regions. By among these you will find food fish breeders, broodstock plants and independent companies that have maintained skirts from various producers.
Where does FiiZK produce it`s products?
FiiZK is committed to creating jobs along the coast. All production takes place at our factories at Lundamo and Fosen in Trøndelag, Norway.
Where does FiiZK get their raw materials from?
All the raw materials we use to tailor lace skirts are manufactured by well-reputed companies in Western Europe. All the parts included in the lace skirt have been thoroughly tested to withstand the tough challenges they face. For FiiZK, it is safe to have a close relationship with our subcontractors, so we have long-term agreements to ensure quality and raw material access. In this way, we can ensure the quality of the products in a proper manner.