Cod fishing is one of the most historically significant and economically important fisheries in the North Atlantic. From the Grand Banks of Newfoundland to the Grand Sole, taking in the fishing grounds of Iceland and Norway, cod fleets have been operating for centuries in some of the most demanding seas on the planet. Today, that activity takes place in a context of greater regulation, increased pressure on fishing grounds, and higher sustainability standards, making choosing equipment a strategic decision, not merely an operational one.
Where and how cod is caught
Understanding how cod is caught at an industrial scale means knowing the fishing grounds where the professional fleet operates and the conditions each one imposes.
The Grand Sole, situated to the south-west of Ireland, is historically the fishing ground most frequented by the Basque and Galician fleets. Its seabeds, at depths of between 100 and 500 metres, hold significant concentrations of Atlantic cod alongside other high-value demersal species. Fishing in the Grand Sole is characterised by adverse weather conditions, strong currents, and large tidal ranges, which place highly demanding requirements on fishing gear — including fishing weights.
Cod is also caught off Newfoundland, in this case at greater depths and in colder waters than in the Grand Sole, with temperatures close to 0°C in the lower layers — adding further demands on the performance of materials. In Iceland and Norway, fishing activity takes place under their own regulatory frameworks, with a strong presence of local fleets and limited access for foreign vessels, although north-east Atlantic cod remains a benchmark in European markets.
Longlining: the dominant method for industrial cod fishing
Longlining is the primary method used in the professional capture of cod at an industrial scale. Bottom longlining consists of a long mainline from which snoods with baited hooks hang, set on the seabed and held in position by sinkers and anchors at both ends.
Compared to trawling, longlining offers greater size selectivity and less impact on the benthic ecosystem, making it the benchmark method in regulated and certified fisheries. In fishing grounds such as the Grand Sole and Newfoundland, where regulatory pressure is high and obtaining certifications conditions access to certain markets, longlining is also the method that best aligns with responsible fishing standards.
Ballast requirements for cod longlining
Ballast in cod longlining faces more extreme conditions than in other demersal Atlantic fisheries. North Atlantic fishing grounds typically operate at depths of between 150 and 600 metres, with occasional forays to greater depths. At those depths, hydrostatic pressure on materials is significant, requiring the weight to maintain its structural integrity without deforming or degrading throughout the duration of the trip.
Temperature adds an additional variable not present in other fisheries. Off Newfoundland and in the deeper areas of the Grand Sole, temperatures in the benthic layer can approach 0°C. Certain materials exhibit changes in their mechanical properties under these conditions — such as embrittlement or variations in effective density — which directly affect the behaviour of the ballast during setting and hauling.
Added to this is the intensity of the currents. Those of the North Atlantic, particularly in the Grand Sole and the Grand Banks of Newfoundland, are irregular and highly powerful. Ballast with insufficient density or an unsuitable shape can cause displacement of the mainline, moving the bait away from the zone where cod are active and drastically reducing the effectiveness of each set.
The duration of fishing trips introduces another critical factor: cod campaigns in the North Atlantic involve periods of up to several weeks away from port. The resistance of the ballast to marine corrosion over that time is no minor detail — it determines its actual service life and, consequently, the replacement cost per campaign.
Finally, in large-scale longlining operations, the loss of sinkers is statistically inevitable. In fishing grounds with strict regulation and active certification processes, the composition of the material left on the seabed is a factor that an increasing number of auditors and certification bodies take into account when assessing the environmental impact of fishing equipment.
Ballast as a factor in MSC certification
MSC certification for cod is particularly relevant in North Atlantic fishing grounds, as it assesses quotas, minimum sizes, and the impact of equipment on the ecosystem. The most rigorous audit schemes include criteria on the materials used in fishing gear, with particular attention to components that may be left on the seabed.
Fleets operating with lead-free weights and non-toxic materials are better positioned to obtain and renew MSC certification, whilst also proactively complying with the regulatory restrictions on the use of lead in fishing gear that the European Union is progressively tightening.
Fishing weights for longlining in the North Atlantic: the SARE range
For the specific conditions of longline fishing in North Atlantic fishing grounds, GreenCastSea's SARE range offers technical solutions designed to meet the demands of depth, temperature, and durability imposed by grounds such as the Grand Sole and Newfoundland.
The SARE SA model, with its robust design and high density, provides the stability needed to keep the mainline in position under strong currents and at great depths. The SARE ST model, with its cylindrical profile, facilitates clean line setting and reduces resistance during hauling, optimising operational times on long fishing trips.
Both models are manufactured from recycled zinc alloy, 100% lead-free, ensuring compliance with international environmental standards and strengthening the fleet's position in MSC certification processes and sustainability audits.
GreenCastSea: equipment for responsible industrial fishing
GreenCastSea develops and manufactures professional fishing weights for fleets operating in the most demanding fishing grounds in the world. Its Itsaspe range — comprising the SARE and HARI lines — covers the requirements of bottom gear, longlines, and nets, with standard models and bespoke solutions manufactured to specification according to the specific conditions of each operation.
All GreenCastSea products are manufactured from recycled zinc alloys, free from lead and toxic materials, making them a technically sound and environmentally responsible alternative to traditional sinkers. A choice that not only improves the fleet's sustainability profile, but also facilitates access to markets and certifications that are increasingly demanding higher standards throughout the entire fishing supply chain.