Fishing By-products : The Sustainable Baits of Tomorrow ?
To attract fish and crustaceans, some pot, trap and longline fisheries still use species such as herring, sardines and sand eels as bait. These resources could also be used for human consumption, while their availability and price fluctuate with the seasons and markets.
The issue is far from insignificant: in some fisheries using passive gears, bait production can account for up to 31% of the life-cycle carbon footprint. In some cases, the volumes of fish used as bait may even exceed the landings of the target species [1]. Recreational fishing faces a related issue through its use of formulated baits and lures, whose composition, water resistance and environmental fate raise new questions.
For several years, the FAO has identified the development of alternatives to marine species used as bait as one possible way to reduce this dependence. Among these alternatives, artificial baits formulated from seafood-processing by-products are attracting growing interest [2].
A closer look at these new developments at the intersection of local valorization, reduced pressure on forage fish and new outlets for by-products.
The different roles of biomass in bait
An artificial bait must perform several functions at once. It must attract the target species, release its compounds into the water at the right rate and remain in place long enough on a hook, in a pot or in a trap.
This is why marine by-products can be studied from several perspectives.
Attractive fractions
Hydrolysates and soluble fractions derived from marine by-products may contain amino acids, peptides and odorous compounds capable of triggering a feeding response.
Research on Atlantic cod has investigated shrimp and mussel hydrolysates as potential alternatives to natural baits. Other trials have observed strong feeding responses to herring-processing by-products, sand-eel hydrolysate and hydrolysates from the shrimp sector [3][4].
A hydrolysate is not, however, a complete bait. It can provide a source of attractants, but it must then be incorporated into a formulation suited to its intended use.
Fractions that structure the bait
The matrix plays an equally important role. It must retain the attractive compounds, allow their gradual release and withstand immersion.
Gelatin and collagen derived from fish by-products are particularly interesting in this respect. One study explored the extraction of gelatin from heads, skins, fins and scales to produce a biodegradable bait matrix. Scales were selected because of their extraction yield and gelling properties [5].
Other research has combined fish-gelatin hydrogels with hydrolysates from squid waste. The aim was to combine structure, attractiveness and protein release in water [6][7].
Key point: in a bait, biomass can serve as an attractant, matrix, binder or release medium. Its value therefore depends as much on its functional properties as on its initial composition.
What do real-world trials show?
Laboratory trials make it possible to compare compositions, matrices and release kinetics. They are not, however, sufficient to predict how a bait will behave at sea.
Temperature, current, depth, turbidity, the abundance of the target species, competition between prey and immersion time can all affect the results. Bait must therefore be assessed in a context close to its final use.
Lobster : an initial by-product-based prototype
A recent study tested a bait made from fish-processing residues and fish hydrolysate, incorporated into a carrageenan-based matrix. In trials conducted under commercial fishing conditions, the best prototype caught approximately 53% as many lobsters as the traditional forage-fish bait [8].
This result does not indicate equivalent performance. It nevertheless shows that a by-product-based formulation can generate a real response at sea and provide a credible basis for further development.
Cod and saithe: monitoring duration of action
In Norway, baits made from shrimp and snow crab by-products were compared with herring in pot fisheries targeting cod and saithe. Catch rates did not differ significantly between the baits tested.
The study mainly highlighted the continuous release of odors over fourteen days, accompanied by the progressive breakdown of the material. Duration of action and water resistance are therefore as important as initial attractiveness [9].
Bio-baits observed in the Bay of Biscay
A study conducted in the Bay of Biscay assessed biodegradable bio-baits formulated from cockles and biopolymers to attract black seabream. Natural baits were more attractive at the beginning of immersion. However, once they had been consumed, the bio-baits continued to attract the fish several hours later [1].
This work is particularly interesting because it did not focus solely on catch numbers. The researchers analyzed more than 127 hours of video footage to study fish behavior around the baits: approach, interest, interaction and duration of presence [1].
These trials show that a good bait cannot be assessed using a single indicator. Catch remains essential, of course, but it must be considered alongside duration of action, mechanical resistance, attractant release, water stability and the behavior of the target species.
Five criteria for a viable bait
To convince a recreational angler or a professional using a longline, pot or trap, a bait must meet several requirements at once.
Attractiveness
The bait must trigger a response in the target species: approach, exploration, mouthing or ingestion. Amino acids, peptides, odorous compounds, taste and texture can all contribute to attraction.
Research nevertheless shows that assembling known molecules is not enough to reproduce a natural bait. The choice of biomass, processing method and formulation remains decisive [1].
Release
Attractive compounds must diffuse through the water at the right rate. Very rapid release can create strong attraction at the beginning of immersion, before the bait quickly loses its effectiveness. Conversely, release that is too slow may limit the olfactory or taste signal.
The objective is to find the right balance between immediate action and an attractive period suited to the use: a few casts for a recreational angler, several hours on a longline or even several days in a pot.
Water resistance
For professional fishing, a bait must remain in the pot, trap or on the hook for a sufficient amount of time. It must withstand water movement, handling, predation by other species and the gradual degradation of the material.
For recreational fishing, resistance also includes the ability to withstand casting and repeated strikes. At the same time, water resistance should be compatible with an appropriate environmental fate if the bait is lost.
This balance is particularly important for synthetic soft lures: research has shown the release of plasticizers from several models studied, as well as the risk of losing these lures during fishing [10].
Selectivity
Ideally, an effective bait should favor the target species and limit interactions with non-target species.
Video analysis can distinguish interest, exploration, mouthing and passing behavior around bio-baits. Understanding which species approaches, when, for how long and in what way is essential for improving selectivity [1].
Economic feasibility
Finally, a bait must work within the economic reality of fishing. Manufacturing cost, the availability and consistency of by-products, storage, packaging, transport resistance, ease of use and seasonality matter just as much as biological performance.
A highly attractive product that is difficult to store, too fragile, too expensive or incompatible with fishing practices is unlikely to be adopted. Conversely, a bait formulated from by-products may be valuable if it uses locally available material and reduces supply uncertainty.
The role of hydrolysis in formulation
Enzymatic hydrolysis can transform the proteins in a marine by-product into more soluble fractions rich in peptides, amino acids and odorous compounds. These fractions can then be studied as sources of attractants or incorporated into a matrix.
Research on cod shows that hydrolysates from shrimp, mussel, herring and sand-eel by-products can trigger a feeding response. Other studies have incorporated hydrolyzed squid-waste concentrates into fish-gelatin matrices. The aim was to combine attractiveness with protein release in water [3][4][6].
The process is only part of the solution. Bait effectiveness depends on the combination of biomass, hydrolysis process, matrix, diffusion kinetics and conditions of use.
From the Laboratory to the Sea
Formulating bait in the laboratory is an essential step: it makes it possible to select a biomass, compare different matrices, adjust texture and measure the release rate of an attractant. It cannot, by itself, predict how the product will behave at sea.
Water temperature, current, depth, turbidity, light, natural prey availability, target-species density and the presence of competing species can all change the results. The same bait can therefore perform differently depending on location, season, fishing gear or immersion time.
Scaling up requires several stages of validation : producing representative batches, checking formulation reproducibility, measuring water resistance and release under conditions close to actual use, and then testing the product against the realities of recreational and professional fishing.
The available studies show that this stage can significantly alter the conclusions. A bait may display good physical properties in the laboratory yet perform less well than a commercial bait at sea. Conversely, a formulation that produces fewer catches may remain active for a longer period. Performance must therefore be defined according to the intended use, rather than through a single indicator.
Conclusion : the right bait closes several loops
Baits made from marine by-products can reduce dependence on resources specifically caught for this purpose, create new value from processing fractions and support new local value chains. Circularity becomes tangible when the bait combines performance, water resistance, safety, availability, economic viability and user acceptance.
At Upcyclink, we explore processing routes that can create new uses for by-products. Developing an artificial bait raises a simple but demanding question: how can an available biomass be transformed into a product that is genuinely functional, reproducible and adapted to fishing conditions?
That is the purpose of R&D serving practical valorization.
Sources
[1] Abangan A. et al. (2024), “Assessment of sustainable baits for passive fishing gears through automatic fish behavior recognition”, Scientific Reports, DOI: 10.1038/s41598-024-63929-5.
[2] FAO, “Fishing operations”, technical document on alternative baits made from processing by-products.
[3] Siikavuopio S. et al. (2017), “Evaluation of protein hydrolysate of by-product from the fish industry for inclusion in bait for longline and pot fisheries of Atlantic cod”, Fisheries Research, DOI: 10.1016/j.fishres.2016.11.024.
[4] Utne-Palm A. C. et al. (2020), “Feeding response of Atlantic cod to attractants made from by-products from the fishing industry”, Fisheries Research, DOI: 10.1016/j.fishres.2020.105535.
[5] Masilan K. et al. (2021), “Valorization of discarded industrial fish processing wastes for the extraction of gelatin to use as biodegradable fish bait matrix using RSM”, PeerJ Materials Science, DOI: 10.7717/peerj-matsci.14.
[6] Masilan K. et al. (2022), “Development of fish gelatin-based artificial fish baits incorporating bioattractants from seafood processing waste”, Journal of the Indian Chemical Society, DOI: 10.1016/j.jics.2022.100376.
[7] Masilan K. et al. (2022), “Investigation on the coacervation of fish scale gelatin hydrogel with seafood waste hydrolysates for the development of artificial fish bait”, Journal of the Indian Chemical Society, DOI: 10.1016/j.jics.2022.100783.
[8] DiFiore B. P. et al. (2025), “An alternative bait for the American lobster fishery composed of fishery by-products to reduce reliance on forage fish”, Fisheries Research, DOI: 10.1016/j.fishres.2025.107389.
[9] Siikavuopio S. et al. (2017), “Testing baits prepared from by-product of the shrimp and snow crab industry in the pot fishery for cod and saithe”, Journal of Applied Ichthyology, DOI: 10.1111/jai.13468.
[10] Thünen Institute, “Harmful substances in soft plastic lures: risks for anglers and the environment”.
To attract fish and crustaceans, some pot, trap and longline fisheries still use species such as herring, sardines and sand eels as bait. These resources could also be used for human consumption, while their availability and price fluctuate with the seasons and markets.
The issue is far from insignificant: in some fisheries using passive gears, bait production can account for up to 31% of the life-cycle carbon footprint. In some cases, the volumes of fish used as bait may even exceed the landings of the target species [1]. Recreational fishing faces a related issue through its use of formulated baits and lures, whose composition, water resistance and environmental fate raise new questions.
For several years, the FAO has identified the development of alternatives to marine species used as bait as one possible way to reduce this dependence. Among these alternatives, artificial baits formulated from seafood-processing by-products are attracting growing interest [2].
A closer look at these new developments at the intersection of local valorization, reduced pressure on forage fish and new outlets for by-products.
The Different Roles of Biomass in Bait
An artificial bait must perform several functions at once. It must attract the target species, release its compounds into the water at the right rate and remain in place long enough on a hook, in a pot or in a trap.
This is why marine by-products can be studied from several perspectives.
Attractive fractions
Hydrolysates and soluble fractions derived from marine by-products may contain amino acids, peptides and odorous compounds capable of triggering a feeding response.
Research on Atlantic cod has investigated shrimp and mussel hydrolysates as potential alternatives to natural baits. Other trials have observed strong feeding responses to herring-processing by-products, sand-eel hydrolysate and hydrolysates from the shrimp sector [3][4].
A hydrolysate is not, however, a complete bait. It can provide a source of attractants, but it must then be incorporated into a formulation suited to its intended use.
Fractions that structure the bait
The matrix plays an equally important role. It must retain the attractive compounds, allow their gradual release and withstand immersion.
Gelatin and collagen derived from fish by-products are particularly interesting in this respect. One study explored the extraction of gelatin from heads, skins, fins and scales to produce a biodegradable bait matrix. Scales were selected because of their extraction yield and gelling properties [5].
Other research has combined fish-gelatin hydrogels with hydrolysates from squid waste. The aim was to combine structure, attractiveness and protein release in water [6][7].
Key point: in a bait, biomass can serve as an attractant, matrix, binder or release medium. Its value therefore depends as much on its functional properties as on its initial composition.
What Do Real-World Trials Show?
Laboratory trials make it possible to compare compositions, matrices and release kinetics. They are not, however, sufficient to predict how a bait will behave at sea.
Temperature, current, depth, turbidity, the abundance of the target species, competition between prey and immersion time can all affect the results. Bait must therefore be assessed in a context close to its final use.
Lobster: an initial by-product-based prototype
A recent study tested a bait made from fish-processing residues and fish hydrolysate, incorporated into a carrageenan-based matrix. In trials conducted under commercial fishing conditions, the best prototype caught approximately 53% as many lobsters as the traditional forage-fish bait [8].
This result does not indicate equivalent performance. It nevertheless shows that a by-product-based formulation can generate a real response at sea and provide a credible basis for further development.
Cod and saithe: monitoring duration of action
In Norway, baits made from shrimp and snow crab by-products were compared with herring in pot fisheries targeting cod and saithe. Catch rates did not differ significantly between the baits tested.
The study mainly highlighted the continuous release of odors over fourteen days, accompanied by the progressive breakdown of the material. Duration of action and water resistance are therefore as important as initial attractiveness [9].
Bio-baits observed in the Bay of Biscay
A study conducted in the Bay of Biscay assessed biodegradable bio-baits formulated from cockles and biopolymers to attract black seabream. Natural baits were more attractive at the beginning of immersion. However, once they had been consumed, the bio-baits continued to attract the fish several hours later [1].
This work is particularly interesting because it did not focus solely on catch numbers. The researchers analyzed more than 127 hours of video footage to study fish behavior around the baits: approach, interest, interaction and duration of presence [1].
These trials show that a good bait cannot be assessed using a single indicator. Catch remains essential, of course, but it must be considered alongside duration of action, mechanical resistance, attractant release, water stability and the behavior of the target species.
Five Criteria for a Viable Bait
To convince a recreational angler or a professional using a longline, pot or trap, a bait must meet several requirements at once.
Attractiveness
The bait must trigger a response in the target species: approach, exploration, mouthing or ingestion. Amino acids, peptides, odorous compounds, taste and texture can all contribute to attraction.
Research nevertheless shows that assembling known molecules is not enough to reproduce a natural bait. The choice of biomass, processing method and formulation remains decisive [1].
Release
Attractive compounds must diffuse through the water at the right rate. Very rapid release can create strong attraction at the beginning of immersion, before the bait quickly loses its effectiveness. Conversely, release that is too slow may limit the olfactory or taste signal.
The objective is to find the right balance between immediate action and an attractive period suited to the use: a few casts for a recreational angler, several hours on a longline or even several days in a pot.
Water resistance
For professional fishing, a bait must remain in the pot, trap or on the hook for a sufficient amount of time. It must withstand water movement, handling, predation by other species and the gradual degradation of the material.
For recreational fishing, resistance also includes the ability to withstand casting and repeated strikes. At the same time, water resistance should be compatible with an appropriate environmental fate if the bait is lost.
This balance is particularly important for synthetic soft lures: research has shown the release of plasticizers from several models studied, as well as the risk of losing these lures during fishing [10].
Selectivity
Ideally, an effective bait should favor the target species and limit interactions with non-target species.
Video analysis can distinguish interest, exploration, mouthing and passing behavior around bio-baits. Understanding which species approaches, when, for how long and in what way is essential for improving selectivity [1].
Economic feasibility
Finally, a bait must work within the economic reality of fishing. Manufacturing cost, the availability and consistency of by-products, storage, packaging, transport resistance, ease of use and seasonality matter just as much as biological performance.
A highly attractive product that is difficult to store, too fragile, too expensive or incompatible with fishing practices is unlikely to be adopted. Conversely, a bait formulated from by-products may be valuable if it uses locally available material and reduces supply uncertainty.
The Role of Hydrolysis in Formulation
Enzymatic hydrolysis can transform the proteins in a marine by-product into more soluble fractions rich in peptides, amino acids and odorous compounds. These fractions can then be studied as sources of attractants or incorporated into a matrix.
Research on cod shows that hydrolysates from shrimp, mussel, herring and sand-eel by-products can trigger a feeding response. Other studies have incorporated hydrolyzed squid-waste concentrates into fish-gelatin matrices. The aim was to combine attractiveness with protein release in water [3][4][6].
The process is only part of the solution. Bait effectiveness depends on the combination of biomass, hydrolysis process, matrix, diffusion kinetics and conditions of use.
From the Laboratory to the Sea
Formulating bait in the laboratory is an essential step: it makes it possible to select a biomass, compare different matrices, adjust texture and measure the release rate of an attractant. It cannot, by itself, predict how the product will behave at sea.
Water temperature, current, depth, turbidity, light, natural prey availability, target-species density and the presence of competing species can all change the results. The same bait can therefore perform differently depending on location, season, fishing gear or immersion time.
Scaling up requires several stages of validation : producing representative batches, checking formulation reproducibility, measuring water resistance and release under conditions close to actual use, and then testing the product against the realities of recreational and professional fishing.
The available studies show that this stage can significantly alter the conclusions. A bait may display good physical properties in the laboratory yet perform less well than a commercial bait at sea. Conversely, a formulation that produces fewer catches may remain active for a longer period. Performance must therefore be defined according to the intended use, rather than through a single indicator.
Conclusion : The Right Bait Closes Several Loops
Baits made from marine by-products can reduce dependence on resources specifically caught for this purpose, create new value from processing fractions and support new local value chains. Circularity becomes tangible when the bait combines performance, water resistance, safety, availability, economic viability and user acceptance.
At Upcyclink, we explore processing routes that can create new uses for by-products. Developing an artificial bait raises a simple but demanding question: how can an available biomass be transformed into a product that is genuinely functional, reproducible and adapted to fishing conditions?
That is the purpose of R&D serving practical valorization.
Sources
[1] Abangan A. et al. (2024), “Assessment of sustainable baits for passive fishing gears through automatic fish behavior recognition”, Scientific Reports, DOI: 10.1038/s41598-024-63929-5.
[2] FAO, “Fishing operations”, technical document on alternative baits made from processing by-products.
[3] Siikavuopio S. et al. (2017), “Evaluation of protein hydrolysate of by-product from the fish industry for inclusion in bait for longline and pot fisheries of Atlantic cod”, Fisheries Research, DOI: 10.1016/j.fishres.2016.11.024.
[4] Utne-Palm A. C. et al. (2020), “Feeding response of Atlantic cod to attractants made from by-products from the fishing industry”, Fisheries Research, DOI: 10.1016/j.fishres.2020.105535.
[5] Masilan K. et al. (2021), “Valorization of discarded industrial fish processing wastes for the extraction of gelatin to use as biodegradable fish bait matrix using RSM”, PeerJ Materials Science, DOI: 10.7717/peerj-matsci.14.
[6] Masilan K. et al. (2022), “Development of fish gelatin-based artificial fish baits incorporating bioattractants from seafood processing waste”, Journal of the Indian Chemical Society, DOI: 10.1016/j.jics.2022.100376.
[7] Masilan K. et al. (2022), “Investigation on the coacervation of fish scale gelatin hydrogel with seafood waste hydrolysates for the development of artificial fish bait”, Journal of the Indian Chemical Society, DOI: 10.1016/j.jics.2022.100783.
[8] DiFiore B. P. et al. (2025), “An alternative bait for the American lobster fishery composed of fishery by-products to reduce reliance on forage fish”, Fisheries Research, DOI: 10.1016/j.fishres.2025.107389.
[9] Siikavuopio S. et al. (2017), “Testing baits prepared from by-product of the shrimp and snow crab industry in the pot fishery for cod and saithe”, Journal of Applied Ichthyology, DOI: 10.1111/jai.13468.
[10] Thünen Institute, “Harmful substances in soft plastic lures: risks for anglers and the environment”.
