Modern ocean-based farmed salmon containment systems are much more than simply floating ‘pens’ used to restrain the geographic movement of salmon during their later growth and development.
Rather, today’s containment options are integrated, technologically-sophisticated production systems strategically designed, operated and maintained to ensure economic, environmental, and social sustainability.
BC salmon farmers have a commitment to invest in infrastructure and practices to optimize farmed salmon containment, with a goal of zero fish escapes.
Net pen systems have evolved significantly from their wood-based predecessors.
The most common coastal net pen systems currently used by BC salmon farms are steel square net systems and high-density polyethylene (HDPE) circle net systems.
These systems are engineered, built, and anchored to the specifications of the operational environment.
Current net pens are anchored to the seabed via sophisticated mooring systems designed and modelled by engineering firms to ensure fitment for the conditions of the infrastructure and the site e.g. engineered to dampen the forces generated by site-specific wave motion.
Modern mooring systems can be a combination of wire and/or synthetic ropes, tackle (shackles, thimbles, masterlinks, etc.), concrete blocks, shovel anchors and buoys—all interconnected in a manner that ensures the integrity of the system, even in the harshest conditions. The components of these anchoring arrays are constantly being improved to allow for longer life, easier deployment, and a greater safety margin—thereby reducing the potential for the escape of farmed fish.
Currently, the most common synthetic polymers used for the manufacture of nets and ropes are nylon or polyamide (PA); polyester (PES); polypropylene (PP); and high-performance polyethylene (Dyneema™ or Spectra™). Polyester and polypropylene fibres can be braided together to create netting with the combined characteristics of the two polymers. All of these polymers are non-water-soluble and therefore provide excellent and long-lasting durability, strength, and reliability in the marine environment.
While both knotted and knotless netting is available for use in net pens systems, knotless netting has now almost completely replaced knotted varieties. The advantages of knotless nets include: lighter weight (>50% lighter than knotted); lower production costs; lower potential to cause abrasion; easier to handle; and greater strength.
