For decades, fishing and aquaculture nets have been designed around one central goal: durability.
Conventional polyethylene, polypropylene, nylon, and polyester netting can remain strong through repeated immersion, hauling, sunlight exposure, and abrasion. That durability is valuable during normal operations, but it creates a serious problem when fishing gear is lost or abandoned.
A conventional net may remain in the marine environment long after it stops serving its owner. Lost gillnets and traps can continue catching fish and other animals—a process known as ghost fishing—and fragmented gear may contribute to long-term plastic pollution. FAO has identified biodegradable materials and time-release components as possible ways to reduce the duration of ghost fishing in certain passive gears. (FAOHome)
Biodegradable marine nets are being developed as one possible response.
However, they are not simply “eco-friendly replacements” that can be used anywhere conventional nets are used. Their value depends on the project duration, required strength, recovery plan, water conditions, target species, and the way the material actually degrades.
For seasonal fishing and temporary coastal work, biodegradable netting may offer useful advantages—but only when its limitations are understood.
A biodegradable marine net is made wholly or partly from a material designed to be broken down by microorganisms under suitable environmental conditions.
Depending on the formulation, candidate materials may include:
Polybutylene succinate, or PBS
Polybutylene adipate-co-terephthalate, or PBAT
Polyhydroxyalkanoates, or PHAs
Polyhydroxybutyrate, or PHB
Polylactic acid, or PLA
Starch-based blends
Biobased polyester blends
Other specially formulated degradable polymers
Research into marine and aquaculture applications is continuing, and different materials can show very different mechanical and degradation behavior. Recent reviews describe several biopolymer families as promising for netting, while also emphasizing the need to match mechanical performance and marine degradation to the intended use. (ScienceDirect)
A biodegradable net should not be confused with a biobased net.
“Biobased” describes where the raw material comes from. It does not automatically mean the finished plastic will biodegrade in seawater. The European Commission specifically distinguishes biobased plastics from biodegradable plastics and notes that environmental benefits must be assessed across the full life cycle. (Environment)
One of the most common misunderstandings is that biodegradable netting dissolves quickly after entering the sea.
That is not how most products work.
Biodegradation depends on factors such as:
Polymer formulation
Water temperature
Microbial activity
Oxygen availability
Sunlight
Water depth
Salinity
Surface area
Twine diameter
Biofouling
Mechanical damage
Time
A material that degrades under industrial composting conditions may not degrade at the same rate in cold seawater. Likewise, a thin laboratory film may break down differently from a thick, twisted netting twine.
Therefore, any claim that a net is biodegradable should be accompanied by information about the test environment, test method, expected time frame, and remaining material after degradation.
Biodegradability is an end-of-life property. It is not permission to deliberately leave fishing gear in the sea.
Seasonal fisheries operate during a limited period each year.
Examples may include:
Short inshore gillnet seasons
Seasonal crab or lobster fisheries
Temporary bait-fish operations
Small-scale coastal fisheries
Limited-duration research fishing
Fisheries linked to spawning or migration periods
These operations may benefit from gear that remains functional for the planned season but gradually loses strength if it is accidentally lost.
This is especially relevant for passive fishing gear.
A lost trawl stops fishing once towing ends. A lost gillnet or trap can remain in place and continue capturing animals. FAO reports that lost gillnets may continue ghost fishing for months or years, depending on conditions, and identifies degradable materials as one possible mitigation measure. (FAOHome)
The ideal seasonal product would therefore have two distinct phases:
A controlled service phase, during which the net retains enough strength for normal fishing.
A post-loss degradation phase, during which strength declines enough to reduce continued capture and entanglement.
Achieving this balance is technically difficult. If degradation starts too early, the net may fail during fishing. If it starts too late, the environmental benefit becomes smaller.
Biodegradable fishing gear is no longer only a laboratory concept.
A 2024 Mediterranean study tested bioplastic gillnets made from a biobased polyester blend on 10 small-scale inshore vessels over 12 months. The research examined both operational performance and fishermen’s acceptance, showing that biodegradable gillnets can be tested under real commercial conditions rather than only in controlled facilities. (ScienceDirect)
Other research programs have tested biodegradable twines in traps and pots, including components designed to weaken after gear loss so that animals can escape. FAO publications have reported trials using biodegradable twines to secure trap entrances or disable unattended fishing gear. (FAOHome)
However, field performance is not always identical to conventional plastic gear.
Possible differences include:
Lower initial breaking strength
Faster loss of strength
Greater stiffness
Different knot behavior
Different visibility underwater
Changes in catch efficiency
Higher material cost
Limited supply
More demanding storage requirements
A biodegradable net should therefore be tested for the exact fishery before being adopted at full scale.
Biodegradable or partially degradable netting may also be considered for temporary coastal projects where the structure is installed for weeks or months rather than years.
Possible examples include:
Short-term exclusion zones
Temporary fish-guidance barriers
Juvenile-fish protection during construction
Seasonal jellyfish barriers
Temporary debris-control screens
Coastal restoration trials
Short-term ecological monitoring
Temporary shellfish or seaweed-support structures
The potential advantage is not that the gear can be abandoned. All temporary structures should still have a recovery and disposal plan.
The advantage is that accidental loss may create a lower long-term persistence risk than conventional plastic netting, provided the material genuinely degrades under the local marine conditions.
Before biodegradable material is selected, project managers must still assess:
Current and wave loading
Expected deployment time
Required mesh size
Wildlife-entanglement risk
Navigation risk
Abrasion against rocks or structures
Inspection frequency
Emergency removal procedures
Local environmental regulations
Temporary does not mean low-risk.
A poorly designed biodegradable barrier can still trap wildlife, detach from anchors, damage habitats, or fail before the project is complete.
Some restoration projects require temporary containment or protection while plants, shellfish, or sediments become established.
Potential applications may include:
Seagrass restoration support
Temporary protection around planted areas
Shellfish-restoration trials
Sediment-retention experiments
Small nursery enclosures
Research plots in shallow water
In these settings, conventional plastic mesh may become difficult to retrieve if storms, burial, or vegetation growth make removal complicated.
A carefully selected degradable material could reduce persistent plastic if part of the structure cannot be recovered.
However, degradation products must also be evaluated.
A material is not automatically environmentally safe merely because it breaks into smaller pieces. True biodegradation should ultimately convert the polymer into substances such as biomass, water, carbon dioxide, or methane under defined conditions—not merely fragment it into microplastics.
This distinction is essential for restoration projects, where the purpose is to improve habitat quality.
Biodegradable netting may appear attractive for short nursery cycles, temporary grading compartments, juvenile holding, or seasonal shellfish operations.
These applications require caution.
Aquaculture containment failure can release stocked animals, expose them to predators, or mix farmed and wild populations. The net must therefore retain a reliable safety margin throughout the complete production cycle.
Suitable experimental applications may include:
Short-duration nursery partitions
Internal grading panels
Temporary harvest compartments
Shellfish socks or support structures
Research-scale cages
Low-risk non-containment components
It may be less suitable for:
Main offshore cage walls
Long-term predator nets
High-current containment systems
Multi-year installations
Structures where failure could release valuable stock
A biodegradable material should not be placed in a critical containment role unless its strength retention has been demonstrated under the actual temperature, current, fouling, and cleaning conditions.
In many fisheries, replacing the entire net or trap with biodegradable material may not be necessary.
A more practical approach is to include one biodegradable component, such as:
An escape panel
An entrance-securing twine
A degradable fastening cord
A timed-release link
A weak section designed to open after prolonged immersion
If the trap is recovered normally, the component remains functional through the fishing period.
If the trap is lost, the degradable section eventually weakens and creates an opening, reducing ghost fishing.
This design concentrates the biodegradable function where it has the greatest environmental value while allowing the rest of the gear to retain conventional durability.
It can also reduce cost and make performance easier to control.
Marine scientists frequently deploy nets and enclosures for experiments involving:
Fish behavior
Larval settlement
Shellfish growth
Water-flow studies
Habitat restoration
Predator exclusion
Species monitoring
Research gear is normally recovered, but storms, vessel traffic, anchor failure, or burial can occasionally make recovery impossible.
Biodegradable materials may be useful when:
The trial has a clearly defined short duration
The mechanical load is moderate
The gear is inspected frequently
Failure would not release invasive or farmed animals
The material’s degradation behavior is known
Conventional recovery remains the primary plan
For research, biodegradable netting can also be tested alongside conventional material to measure strength loss, fouling, ecological effects, and recovery performance.
A project may last only a few months and still require conventional high-strength netting.
Biodegradable netting may be unsuitable where there are:
Strong currents
Heavy wave exposure
Rocky seabeds
High abrasion
Large captured animals
Critical navigation barriers
Human-safety functions
Long periods without inspection
Severe biofouling
Extreme cold
High-value stock
Uncertain deployment duration
A storm can expose a temporary structure to loads far above those experienced during normal conditions.
The correct question is therefore not:
“Will the net be used for only one season?”
It is:
“Can the net safely withstand every expected load during that season, with an appropriate safety margin?”
A biodegradable net may be strong on the day it is installed, but what matters operationally is how much strength remains over time.
Strength loss may be influenced by:
Hydrolysis
Microbial activity
Ultraviolet exposure
Temperature
Twine flexing
Knot compression
Abrasion
Fouling
Cleaning
Chemical exposure
For seasonal applications, manufacturers should ideally provide a strength-retention profile rather than only a new-product breaking load.
For example, buyers need to understand:
Initial breaking strength
Knot strength
Strength after one month
Strength after the expected season
Behavior after exposure beyond the intended period
Variation between batches
Performance at local water temperatures
A material that retains 95% of its strength for a year may offer little ghost-fishing reduction after loss.
A material that loses half its strength in two weeks may be unsafe for a three-month project.
The desired degradation schedule must match the operating schedule.
Biological and chemical degradation processes are generally affected by temperature.
Warm coastal water may accelerate some processes, while cold deep water may slow them considerably.
This means the same net could behave differently in:
Tropical bays
Temperate estuaries
Cold northern fisheries
Deep offshore water
Shallow sunlit lagoons
A product tested in one location should not automatically be assumed to perform identically in another.
Seasonal timing also matters. A net installed during a warm summer may lose strength differently from one used during winter.
Local testing is especially important when the product has a critical containment or fishing function.
Biofouling complicates biodegradation.
A layer of algae, microorganisms, mussels, barnacles, and sediment may change:
Surface exposure to sunlight
Oxygen availability
Microbial communities
Water movement around the twine
Mechanical loading
Abrasion
Net weight
In some cases, biological growth may contribute to microbial degradation. In others, a heavy fouling layer may shield parts of the polymer from ultraviolet light while increasing mechanical stress.
The final behavior depends on the material and environment.
This is another reason laboratory degradation data cannot fully replace field trials.
A biodegradable net does not stop catching animals immediately after it is lost.
There may be a period of days, weeks, or months during which it remains strong enough to fish.
The duration depends on:
Material
Twine thickness
Gear design
Water conditions
Depth
Temperature
Catch accumulation
Abrasion
Degradation rate
Therefore, biodegradable gear should be combined with prevention and recovery measures such as:
Gear marking
GPS position records
Regular inspections
Retrieval plans
Reporting lost gear
Weak links
Escape panels
Responsible disposal
Biodegradation is a backup risk-reduction measure, not a replacement for responsible gear management.
Environmental claims require careful evaluation.
Questions to ask include:
Does the material fully biodegrade or only fragment?
Under which test conditions?
How long does degradation take?
Are additives released?
Are degradation products toxic?
Does it affect sediment or water chemistry?
Can animals ingest fragments?
Is the product certified under a relevant standard?
Is the certification relevant to marine water rather than compost?
A product certified as industrially compostable may require elevated temperatures and controlled conditions that do not exist in the ocean.
Marine projects need evidence specific to marine or aquatic environments.
Biodegradable netting may have a higher purchase price than standard plastic netting.
However, project cost should also include:
Installation
Inspection
Replacement
Recovery
Disposal
Lost-gear risk
Environmental compliance
Cleanup
Liability
Catch performance
Project failure
For a short coastal project with a high risk of partial loss, the environmental and recovery benefits may justify a higher material price.
For a long-term, high-load aquaculture cage, frequent replacement caused by early strength loss could increase both cost and environmental impact.
The more sustainable choice is not always the material labelled biodegradable. It is the option that meets the function safely while minimizing impact across its full life cycle.
Before purchasing biodegradable marine netting, ask for clear technical information.
Important questions include:
What polymer or blend is used?
Is the material biobased, biodegradable, or both?
Under what conditions was biodegradation tested?
Was testing performed in seawater, freshwater, soil, or compost?
What is the expected service period?
How does breaking strength change over time?
What is the knot-strength performance?
How does temperature affect degradation?
Has the finished net been field-tested?
How does catch performance compare with conventional netting?
Are there restrictions on storage?
What is the recommended disposal method?
Does the product comply with local regulations?
Can mesh size, twine diameter, and panel design be customized?
Is the material suitable for contact with cultured or captured species?
A supplier who cannot explain the degradation environment and strength-retention period may be selling a label rather than a proven marine solution.
Biodegradable netting may be worth evaluating for:
Seasonal passive fishing
Trap escape panels
Degradable trap fasteners
Short-term inshore trials
Temporary ecological barriers
Research enclosures
Low-load restoration projects
Short nursery partitions
Temporary shellfish-support systems
Projects with a realistic risk of accidental loss
It requires greater caution for:
Offshore containment cages
Deep-water trawls
Long-term predator barriers
High-current sites
Rocky seabeds
Multi-year aquaculture installations
Human-safety barriers
Navigation-control structures
Projects with unpredictable duration
The most important principle is simple:
A biodegradable net should still be recovered after use.
Leaving it in the sea wastes material, creates an entanglement risk during the degradation period, and removes the possibility of proper disposal or recycling.
The preferred hierarchy should remain:
Reduce unnecessary gear use.
Design gear to prevent loss.
Mark and track equipment.
Recover it after use.
Reuse or recycle where practical.
Use biodegradability to reduce the consequences of accidental loss.
Biodegradable materials should support responsible operations, not replace them.
Biodegradable marine nets have genuine potential, particularly in seasonal fishing, passive gear, temporary coastal projects, research applications, and selected low-risk aquaculture components.
Their main advantage is not that they can be thrown away.
It is that, if accidentally lost, they may remain active and persistent for a shorter period than conventional plastic gear.
But that benefit depends on careful design.
The net must remain strong enough during the intended operation, then lose functional strength within a useful post-loss period. Its degradation must occur under the actual marine conditions, not only under laboratory or composting conditions.
Before selecting biodegradable netting, buyers should evaluate service time, current, abrasion, water temperature, recovery access, containment risk, and degradation evidence.
For the right seasonal or temporary application, biodegradable netting can become a valuable environmental tool.
For the wrong application, it may fail too early, cost more, or provide little real benefit.
The best choice is not simply the net that degrades.
It is the net that performs safely when needed, can be recovered responsibly, and causes less harm if recovery fails.
