Biodegradable and degradable marine nets are often described in simple terms:
Use them normally, lose them accidentally, and they will eventually disappear.
The reality is far more complicated.
A marine net must survive seawater, sunlight, currents, abrasion, knots, hauling, fish impact, and repeated handling. At the same time, a degradable product is expected to lose strength after its useful life so that lost gear does not remain active for years.
These two goals work against each other.
A net that degrades too slowly may provide little advantage over conventional plastic gear. A net that weakens too quickly may tear during fishing, reduce catch efficiency, or become additional marine debris.
The real challenge is not simply making a net degradable.
It is controlling when, where, and how fast it loses strength.
The terms are often used as though they mean the same thing, but they can describe very different processes.
A degradable material is designed to lose strength or break into smaller pieces through mechanisms such as:
Sunlight exposure
Oxidation
Heat
Hydrolysis
Mechanical wear
Chemical reactions
A biodegradable material is intended to be broken down through biological activity under suitable conditions.
True biodegradation should go beyond visible fragmentation. The polymer should ultimately be converted into simpler substances through biological processes rather than merely becoming smaller plastic particles.
This distinction matters because a net that falls apart into fragments has not necessarily disappeared from the environment.
The European Commission also distinguishes biobased, biodegradable, and compostable plastics. A product made partly from renewable raw materials is not automatically biodegradable, and a material that composts in an industrial facility may not break down effectively in seawater. (Environment)
The phrase “marine-grade degradable netting” sounds reassuring, but it does not explain how the product will behave.
A buyer still needs to know:
What polymer or blend is used?
Is it monofilament, multifilament, twisted, or braided?
How strong is it when new?
How quickly does it lose strength?
Was it tested in seawater or only in compost?
At what water temperature was it tested?
Was the finished net tested, or only a thin plastic film?
Does it biodegrade or mainly fragment?
How does knot strength change over time?
How much batch variation should be expected?
Without this information, “marine-grade” may be only a marketing phrase.
A serious product specification should define the working period, expected degradation conditions, test method, and remaining strength after different immersion times.
Before discussing environmental benefits, a fishing net must perform its primary job safely.
During use, it may be exposed to:
Water-current drag
Tidal reversals
Fish impact
Catch accumulation
Hauling loads
Knot compression
Seabed abrasion
Sunlight
Biofouling
Repeated folding
Cleaning and repair
If a degradable net loses strength before the fishing season ends, the result may include:
Escaped catch
Torn panels
Emergency repairs
Lost fishing time
Early replacement
Additional gear loss
Higher operating costs
This is why initial breaking strength alone is not enough.
The more important question is:
How much strength will remain after the complete operating period?
A net that is strong on installation day but unreliable after several weeks is not suitable for a three-month season.
Premature failure usually does not result from one single factor.
It occurs when environmental degradation and mechanical damage act together.
Some biodegradable polymers undergo hydrolysis or other changes after contact with water. Temperature, polymer chemistry, and manufacturing quality affect the speed of this process.
The twine bends sharply at each knot. Even when the straight section remains usable, knot strength may decline more quickly.
Rocks, shells, frames, ropes, and hauling equipment damage the twine surface. Once degradation has reduced toughness, small scratches can grow into larger cracks.
Parts of a net stored on deck or used near the surface may receive more ultraviolet exposure than sections kept deeper underwater.
Algae, barnacles, mussels, and sediment make the net heavier and increase drag. A material already losing strength may then face greater mechanical stress.
Differences in filament diameter, orientation, twisting, or heat treatment may cause some sections to weaken before others.
Premature failure is therefore often a system problem rather than simply “the material dissolved too fast.”
The opposite problem is also common.
A product may be described as biodegradable but remain physically present in the marine environment for a long time.
Marine degradation can be slow because seawater may provide:
Lower temperatures
Less microbial activity than compost
Limited nutrients
Lower oxygen in sediments
Reduced ultraviolet light at depth
Different microbial communities
Slow water penetration into thick twine
A thin laboratory sample can degrade faster than a finished net because the net has greater thickness, multiple twisted strands, knots, coatings, and lower surface-area-to-volume ratio.
In one study using an ISO marine-sediment method, PBS fishing gear showed partial conversion to carbon dioxide over 180 days rather than complete disappearance, illustrating that marine biodegradation may be gradual and incomplete within a short test period. (ScienceDirect)
This does not mean the material has no value. It means buyers should not expect instant disappearance.
A net may visibly weaken, tear, and disappear from view while polymer fragments remain in the environment.
There are three different stages that should not be confused:
The net can no longer perform as fishing gear.
The twine breaks into smaller pieces.
Microorganisms convert the polymer into simpler end products under defined conditions.
For reducing ghost fishing, loss of functional strength may be the most important early benefit. Once the mesh collapses or an escape panel opens, the gear may stop trapping animals.
For preventing long-term plastic pollution, however, full biodegradation is more important than simple fragmentation.
A product can perform well at the first goal without fully achieving the second.
Lost gillnets and traps may continue capturing animals long after they are abandoned. FAO identifies degradable materials and disabling mechanisms as possible tools for reducing this continued fishing activity. (FAOHome)
But stopping ghost fishing does not always require the entire structure to biodegrade quickly.
The gear may become nonfunctional when:
A panel tears
Mesh loses its shape
A trap entrance opens
A weak link fails
An escape section detaches
The net loses enough strength to collapse
This is why biodegradable escape panels or fastening cords may sometimes be more practical than producing an entire net from degradable material.
The main structure can remain durable during normal fishing, while one designed component disables the gear after prolonged loss.
A successful degradable net should have at least two predictable phases.
Throughout the planned fishing period, the net should maintain sufficient:
Breaking strength
Knot strength
Mesh stability
Abrasion resistance
Flexibility
Catch performance
After the planned service period—or after prolonged unintended immersion—the net should gradually lose enough strength to reduce ghost fishing and long-term persistence.
The difficulty lies in controlling the transition.
If the transition begins too early, the net becomes unsafe.
If it begins years after loss, the environmental advantage is limited.
A 2026 review of biodegradable aquaculture-net materials identified this durability-versus-degradability balance as the central technical challenge and emphasized that marine degradation varies with environmental conditions. (ScienceDirect)
A degradable net does not behave identically in every sea.
Temperature influences chemical reactions and biological activity.
The same product may degrade:
Faster in warm tropical coastal water
More slowly in cold northern seas
Differently in shallow sunlight-exposed water
More slowly in deep or buried environments
Differently during summer and winter
This creates a serious specification problem.
A net designed to remain safe for six months in cold water might weaken too quickly in a warm lagoon. A product tested in tropical water might remain active much longer after loss in a cold deep-water fishery.
The service period must therefore be matched to the real deployment location, not only to a general material datasheet.
Even when the polymer is the same, the finished net may degrade differently depending on its structure.
Important variables include:
Monofilament or multifilament construction
Twine diameter
Number of strands
Twist level
Knot type
Mesh size
Surface coating
Heat setting
Pigments and additives
Thin filaments have more exposed surface relative to their mass and may lose strength faster.
Thicker twine may remain functional longer but may also take much longer to biodegrade fully.
Twisted multifilament twine may trap water, sediment, and microorganisms between strands, but it may also contain internal fibers that remain protected for longer.
Therefore, degradation data from raw polymer pellets or thin films cannot reliably predict the life of a finished fishing net.
Fishing-net specifications often emphasize linear breaking strength.
But many actual failures occur at knots.
A knot:
Bends the twine sharply
Compresses the material
Creates fiber-to-fiber friction
Reduces effective strength
Concentrates repeated loads
A degradable twine may retain acceptable straight-line strength while knot strength has already fallen below a safe level.
Buyers should therefore request both:
Straight-twine breaking strength
Knot breaking strength
These should ideally be measured when new and after relevant periods of seawater exposure.
A product intended for knotless netting may not perform the same way when used in a knotted design.
A degradable net does not need to tear completely before fishing performance changes.
Gradual changes in stiffness, elongation, visibility, diameter, and mesh geometry can affect how the gear fishes.
Possible changes include:
Mesh openings becoming distorted
Net panels becoming softer or stiffer
Fish responding differently to net visibility
Greater pocketing or less entanglement
More frequent net damage during removal of catch
Different handling on deck
Field research has produced mixed results. Some biodegradable trammel nets achieved catch performance comparable to nylon under specific trial conditions, although conventional nylon had stronger physical properties. (ScienceDirect)
Other reviews have warned that reduced ghost fishing may sometimes result from weaker initial gear rather than a carefully controlled decline in strength. (ScienceDirect)
This distinction matters: a net should not be considered environmentally superior simply because it is easier to break.
Marine nets quickly develop biological films and may become covered with algae, hydroids, barnacles, mussels, and sediment.
Fouling can influence degradable materials in several competing ways.
It may:
Increase microbial contact
Retain moisture
Shield the polymer from sunlight
Reduce oxygen at the surface
Increase weight
Increase hydrodynamic drag
Create abrasion
Make cleaning more aggressive
A heavily fouled net may therefore degrade chemically more slowly in some areas while failing mechanically faster because of added load.
This is why field exposure is essential.
Laboratory seawater tests cannot reproduce every combination of fouling, current, catch loading, cleaning, and seasonal temperature.
Some degradable polymers are more sensitive than conventional fishing plastics to storage conditions.
Potential problems include exposure to:
High temperature
Humidity
Direct sunlight
Repeated temperature changes
Chemicals
Long warehouse storage
Damaged packaging
If the material begins aging during transport or storage, the buyer may receive a net with less remaining service life than expected.
Manufacturers should therefore provide:
Recommended storage temperature
Humidity limits
Shelf-life information
Packaging requirements
Production date
Stock-rotation guidance
A fishing operation should not treat degradable netting as unlimited-life inventory.
Repairing a degradable net raises an important question:
Should the repair twine also be degradable?
Using conventional nylon or polyethylene repair twine may create strong patches that remain after the surrounding net weakens.
Using degradable repair twine with a different formulation may create areas that fail too soon.
The repair material should be compatible in:
Diameter
Strength
Elongation
Stiffness
Knot behavior
Expected degradation schedule
Otherwise, the repaired area may alter load distribution or remain as persistent debris after the rest of the net has weakened.
Replacing conventional netting with biodegradable material does not guarantee a lower environmental impact.
The full life cycle should include:
Raw-material production
Energy use
Manufacturing
Transport
Product lifetime
Replacement frequency
Fishing efficiency
Gear-loss risk
Degradation products
End-of-life treatment
If a degradable net must be replaced twice as often, the additional production, transport, packaging, and waste may reduce its overall advantage.
Environmental performance also depends on additives and degradation products. Recent experimental work has cautioned that biobased or biodegradable fishing-net materials are not automatically free from toxicity concerns under severe aging conditions. (ScienceDirect)
“Biodegradable” should therefore be treated as a technical property, not as proof that a product is harmless in every situation.
Marine-grade degradable netting is currently most promising where the working period is clearly defined and lost gear creates a significant ghost-fishing risk.
Suitable trial applications may include:
Seasonal gillnets
Trammel nets
Trap escape panels
Biodegradable trap fasteners
Temporary research nets
Short-term coastal barriers
Selected small-scale fishing operations
Noncritical aquaculture partitions
More caution is required for:
Long-term offshore cage containment
High-load bottom trawls
Permanent predator nets
Strong-current barriers
Multi-year structures
Very cold deep-water operations
Gear that cannot be inspected frequently
Applications where failure creates a major safety risk
The decision should depend on service requirements rather than on environmental branding alone.
Before purchasing, buyers should request evidence addressing several practical questions.
Testing raw resin or thin film is not enough.
Look for performance after realistic immersion periods, not only initial strength.
Knot performance can determine actual service life.
Warm- and cold-water results may differ substantially.
Real nets contact equipment, catch, seabeds, and shells.
A net that catches significantly less may not be commercially viable.
Claims such as “degrades naturally” are too vague.
Premature aging may begin before deployment.
A reliable supplier should be able to explain both the product’s strengths and its limitations.
Fishing operations should avoid replacing an entire fleet immediately.
A safer trial can include:
Select a small number of biodegradable panels.
Keep conventional gear as a control.
Use both under similar conditions.
Record initial strength and dimensions.
Track fishing days and immersion time.
Measure catch per unit effort.
Inspect knots, seams, and abrasion points.
Record repairs and handling differences.
Retest strength at planned intervals.
Continue monitoring beyond the normal season where permitted.
Evaluate disposal or recovery at the end.
The goal is to establish whether the net remains reliable for the intended service period—not simply whether it survives the first few trips.
A meaningful degradable-net specification should include:
Polymer type and formulation category
Net construction
Twine diameter
Mesh size
Initial breaking strength
Knot strength
Elongation
Abrasion performance
Strength-retention data
Test temperature
Immersion environment
Test duration
Biodegradation test method
Storage recommendations
Expected service period
Recommended application
Known limitations
Without these details, buyers cannot distinguish a controlled marine product from an ordinary weak plastic marketed as environmentally friendly.
Even genuinely biodegradable fishing gear should be recovered after use.
A degradable net can still:
Catch animals before it weakens
Entangle wildlife
Damage coral or seagrass
Create navigation hazards
Break into fragments
Become buried in sediment
FAO guidance continues to emphasize prevention, gear marking, reporting, and recovery as major responses to abandoned, lost, or otherwise discarded fishing gear. (FAOHome)
Biodegradation should reduce the consequences when recovery fails.
It should not replace responsible gear management.
Marine-grade degradable netting does not face a simple choice between “disappearing naturally” and “remaining forever.”
Its real performance lies somewhere between those extremes.
A successful product must remain strong through its full fishing period, then lose functional strength quickly enough to reduce ghost fishing if it is lost. It should ultimately biodegrade under relevant marine conditions rather than merely fragment into smaller pieces.
That balance depends on polymer formulation, twine diameter, knots, water temperature, abrasion, sunlight, biofouling, storage, and the intended application.
The greatest risk is not only that the net degrades too slowly.
It is also that it begins failing while the operator still depends on it.
Buyers should therefore look beyond environmental labels and ask for finished-product strength retention, knot tests, marine degradation evidence, field results, and a clearly defined service window.
The best degradable net is not the one that disappears fastest.
It is the one that remains reliable exactly as long as it is needed—and becomes less harmful if it is never recovered.
