AU2021265805A1 - Marine fishery trap baits and deterrents - Google Patents

Abstract

Processes for encapsulating bio-affecting compositions comprising attractants, deterrents, and/or nutrients for inclusion in calcium sulphate blocks to reduce the rate of block degradation during storage or when placed in water when used as trap baits and deterrents for attracting, deterring and/or feeding aquatic species, particularly during fishing for decapod crustaceans.

Description

Marine Fishery Trap Baits and Deterrents

Technical Field

[0001] The present invention relates to processes for forming trap baits and deterrents for use in fisheries. More particularly, the present invention relates to processes for encapsulating bio-affecting compositions comprising attractants, deterrents, and/or nutrients for inclusion in calcium sulphate blocks to reduce the rate of block degradation when placed in water for use in attracting, deterring or feeding aquatic species.

Background Art

[0002] Bait traps are used in the commercial and recreational catch, capture and harvesting of high value decapod crustaceans including lobsters, rock lobsters, crayfish, and crabs amongst other aquatic species.

[0003] Traditionally, bait traps including crab and lobster/crayfish pots are baited with whole or parts of dead fish (and/or other farmed animals including, for example, chickens and cows). In use, the fish parts are placed directly into the bait trap or within a porous bag or cage within the bait trap. The commonly portable bait traps are dropped from a fishing boat and sink to the sea floor in a desired location.

[0004] The crustaceans move by walking, crawling, and swimming and are attracted to enter the bait trap through an entryway by the attractants and nutrients released into the surrounding water by the decomposing organic bait.

[0005] Bait traps used by fishermen comprise a variety of different configurations and materials which are chosen for reasons including cost, availability, storage, weight, and individual preference or historical reasons, amongst others. However, they usually all include permeable walls surrounding a trap area, accessible by a single, or multiple entryways. The trap area includes a bait holder, for example, a bait basket, or a porous bag or cage which enables the bait to contact the surrounding water into which its attractants and nutrients are released as it decomposes. However, the bait is prevented from easily exiting the trap as the trap is dropped into the water and sinks to the bottom.

[0006] The fish material of the bait leaches soluble fractions, creating plumes of attractant chemicals that stimulate chemosensory and olfactory sensors of target crustacean species. This motivates the crustaceans to follow the plume and enter a bait trap. Once in the bait trap, a combination of chemosensory stimuli, internal motivations and phagostimulants from the bait, motivate the crustaceans to manipulate and ingest the fish material and remain in the bait trap until the bait trap is retrieved.

[0007] Bait traps generally have an entryway that is configured to allow easy entry of a crustacean into the trap, but makes it difficult to exit the trap. The aim being to keep crustaceans in the bait trap while maintaining an open entryway to allow further crustaceans to enter the bait trap and preferably remain there until the bait trap is retrieved.

[0008] While the configuration of the bait traps makes it difficult for captured crustaceans to exit the entryway, the entryway is often not closed off completely. Therefore, given enough time crustaceans will begin to escape the trap once the bait is finished. The bait is considered finished once it is either eaten by caught crustaceans or fish entering and exiting the trap, or washed away as it decomposes. Thus, fisherman rely on their experience to balance when to lift the trap when hopefully (i) as many crustaceans have had sufficient time in which to be attracted and caught within the trap, but (ii) before the bait is finished and some or all of the caught crustaceans have time to escape the trap.

[0009] However, a significant problem with the use of (usually frozen) fish parts as bait is that their duration/persistence in the bait trap is limited to approximately 24 to 48 hours. This is due to the rapid decay and liquification of the flesh, and also due to grazing by small scavenging animals, including amphipods, isopods, small decapods and small fish. The fish parts are also soft and can be rapidly consumed by target crustaceans in the bait trap. Once the baits have sufficiently degraded or disappeared due to these processes, they will not then attract further crustaceans into the bait trap, and in traps with one or more open entryways, trapped crustaceans will usually exit the bait trap without the ongoing stimulus to remain.

[0010] Thus, negative aspects of using conventional fish and/or animal baits include:

- short duration/persistence of bait attractiveness in bait traps, for approximately 24 to 48 hours. Therefore, requiring short set times of bait traps;

- relatively large volumes of bait required per bait trap; - with trap fisheries using 1 to 8 times as much bait as harvested crustaceans;

- high energy and logistical costs with transport and storage of frozen baits;

- use of high-quality fish as bait with real or perceived issues of the sustainability of baits sourced from wild fisheries;

- low specificity of natural fish baits which can attract non-target scavengers and predators like octopus that consume trapped crustaceans and deter others from entering the bait trap; and

- biosecurity risks from use of raw imported fish bait materials.

[0011] One means that has been foreshadowed to push this balance in the fisherman’s favour is the design of synthetic baits incorporating organic molecules which are primarily amino acids (WO2015/191136). The amino acids were identified as some of the attractants in dead bait fish as determined by neurophysiological assessment of the chemosensory sensitivities of decapod lobsters. These amino acids were encased within an inert medium which was predominantly calcium sulphate hemi-hydrate (‘Plaster of Paris’) and dried into a cake or ‘bait block’ which could be placed in the bait basket of a lobster pot and could last up to 40 days before fully dissolving.

[0012] When deployed in the bait trap, the amino acids can dissolve into aqueous phase in and around the synthetic bait block as the Plaster of Paris block gradually dissolves from the outside in from contact with the water. The released amino acids create chemical concentration gradients in the surrounding water that the lobsters can detect and follow towards and into the trap.

[0013] Considerable advantages could be provided by such synthetic baits in removing the requirement of the large amounts of fish offal usually required and the associated environmental impact, transport, storage, etc. However, these synthetic baits are considerably more expensive to manufacture due to the high cost of the synthetic amino acid molecule attractants used. It would therefore, likely be more difficult to convince fishermen to replace their current bait with a more expensive alternative, regardless of the other advantages.

[0014] It would therefore be of benefit to provide an alternative manufactured bait that provided some of the advantages of synthetic baits, but at a lower cost and/or comparable or improved efficacy to compete with the currently used fish and offal baits.

[0015] The preceding discussion of the background art is included exclusively for the purpose of providing a context for the present invention. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in the field relevant to the present invention in Australia or elsewhere before the priority date.

[0016] Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0017] Each document, reference, patent application or patent cited in this text is expressly incorporated herein in their entirety by reference, which means that it should be read and considered by the reader as part of this text. That the document, reference, patent application, or patent cited in this text is not repeated in this text is merely for reasons for conciseness.

Summary of the Invention [0018] The invention provides a process of forming a bio-affecting block for use in an aquatic environment to attract, deter and/or feed aquatic species, the process comprising the steps: encapsulation of one or more bio-affecting compositions; combining the encapsulated bio-affecting compositions with an inert medium and a solvent to form a mixture; and drying the mixture to form a block; wherein when the block is placed in water, it will gradually dissolve and release the encapsulated bio-affecting compositions into the surrounding water.

[0019] The bio-affecting compositions preferably comprise attractants, deterrents, and/or nutrients for aquatic species.

[0020] In attempting to create lower cost manufactured baits, the inventor identified that the chemistry of the setting of calcium sulphate hemi-hydrate (Plaster of Paris) is very sensitive to interference by a range or organic and inorganic chemicals. In this respect, many of the recognised attractants and excipients that could in theory be used in a manufactured bait product as an alternative to the expensive purified or synthetic amino acid molecules actually inhibit the optimal setting of the calcium sulphate matrix. This includes fish meals, protein hydrolysates, fish product ferments, salts, sugars, acids, buffers, preservatives, legume meals. Thus, the setting of a synthetic bait of Plaster of Paris using the methods of WO2015/191136 is limited to only low levels of purified amino acids. However, the inventor made the discovery that implementation of techniques from other industries could be employed to encapsulate these more complex and often moisture-containing attractants. This would protect the setting calcium sulphate matrix during formation of the block to reduce the rate of degradation from the inside out during storage and use.

[0021 ] In a preferred embodiment, the step of encapsulation of the one or more bio-affecting compositions comprises the process of matrix encapsulation. [0022] The step of encapsulation preferably comprises a step of mixing and concentrating bio-affecting compositions to form an aqueous paste. The bio affecting compositions are preferably in powder and/or liquid forms of the raw form of the bio-affecting compositions and are combined together to form a paste.

[0023] In a preferred embodiment, excipients are added to the bio-affecting compositions to form the aqueous paste. The excipients preferably comprise one or more from the group comprising: water or another solvent; inert fillers comprising CaS04, kaolin or other clays, lime, starch, flours, cellulose powders, cellulose fibres; protective and viscosity modifying products comprising hydrocolloids, natural and synthetic gums such as guar gum, xanthan gum, pullulan, carboxymethyl cellulose; stabilising sugars comprising sorbitol, mannitol, trehalose; preservatives compromising sodium benzoate; polyvinyl pyrrolidone, polyvinyl acetate, polyethylene glycol.

[0024] The excipients preferably adjust the viscosity of the aqueous paste to facilitate extrusion of the paste through a metal die. The aqueous paste is preferably made to be substantially firm by adjusting the level of moisture and excipients.

[0025] The aqueous paste is preferably extruded through a die, and preferably, the die is a metal die. The die holes through which the aqueous paste is extruded are preferably between approximately 0.1 mm to 10 mm, more preferably between approximately 0.5 mm and 5 mm, even more preferably between approximately 0.5 mm and 2 mm.

[0026] In a preferred embodiment, the extrusions of paste are dried forming encapsulated bio-affecting compositions. The extrusions of paste are preferably dried on drying racks. Diameters of the dried extrusions are preferably between approximately 0.1 mm to 10 mm, more preferably between approximately 0.5 mm and 5 mm, even more preferably between approximately 0.5 mm and 2 mm.

[0027] At least the outer surface of the extrusions of paste are preferably dry. The encapsulated bio-affecting compositions comprising dried extrusions of paste are preferably cut or broken into smaller portions or particles for incorporation into the block.

[0028] In a preferred embodiment, the step of mixing or combining the encapsulated bio-affecting compositions with an inert medium and a solvent comprises adding solvent to the inert medium. Preferably, the solvent is water.

[0029] In a preferred embodiment, the inert medium is calcium sulphate hemi- hydrate. The calcium sulphate hemi-hydrate is preferably in a powder form.

[0030] The ratio is preferably approximately 0.2 to 1 .0 L of water per kg calcium sulphate hemi-hydrate dry weight, or as is known in the art to form Plaster of Paris.

[0031] In a preferred embodiment, dried portions or particles of encapsulated bio-affecting compositions are added to the water and calcium sulphate hemi- hydrate mix and combined to form the mixture.

[0032] Excipients are preferably added to the mixture which assist to control or modify the (i) setting speed, (ii) un-set viscosity, and/or (iii) hardness and dissolution rate of the block.

[0033] The excipients preferably comprise one or more selected from the group comprising: retarding chemicals; hydrocolloids; sugars; preservatives comprising sodium benzoate; inert or reactive powders or fibres as fillers or providing functional properties. The retarding chemicals (setting time regulators) preferably comprise either or both of tartaric acid and sodium tri polyphosphate. The tartaric acid is preferably added in powder form at between approximately 0.1 % and 2% by weight of the calcium sulphate hemi-hydrate, more preferably between approximately 0.2% and 1 % by weight of the calcium sulphate hemi-hydrate, and even more preferably approximately 0.5% by weight of the calcium sulphate hemi-hydrate. Tartaric acid or other setting time regulators are preferably dissolved in the water used to make up the water and calcium sulphate hemi-hydrate mix. [0034] The inert medium, solvent, encapsulated bio-affecting compositions, and any excipients are preferably mixed together to form a substantially homogenous block-forming mixture.

[0035] In a preferred embodiment, a mould is filled with the block-forming mixture which sets in the mould. The dimensions of the mould are preferably between approximately 20 mm x 40 mm x 40 mm and 300 mm x 300 mm x 300 mm, more preferably between approximately 40 mm x 80 mm x 80 mm and 200 mm x 200 mm x 200 mm, and even more preferably between approximately 50 mm x 100 mm x 100 mm and 120 mm x 120 mm x 120 mm.

[0036] In a preferred embodiment, the block-forming mixture is pumped into a mould. The pump is preferably suitable for pumping high viscosity pastes. The pump is preferably selected from one of the group comprising: progressive cavity pumps, peristaltic pump, Lobe pump, and auger style extruder.

[0037] Once the block-forming mixture has set, the formed block is preferably removed from the mould and dried. The formed block is preferably dried in a in controlled environment dryer, or air dried.

[0038] In a preferred embodiment, the block comprises soluble, encapsulated attractants, deterrents, and/or nutrients at inclusion rates of between approximately 1 % to 20%, more preferably between approximately 2% and 10%, and even more preferably approximately 5%.

[0039] In a preferred embodiment, bio-affecting compositions, compounds or molecules are applied to the outer surface of the dried block. Application of the bio-affecting compositions, compounds or molecules to the outer surface of the dried block is preferably by spraying or coating.

[0040] The invention further provides for the use of a bio-affecting block formed by a process as described herein as a bait block to attract aquatic species. In a preferred embodiment, the aquatic species are decapods and decapod crustaceans. The bait block is preferably used in a trap for capturing decapods, and more preferably capturing lobster, crayfish, and/or crabs. [0041 ] The invention further provides for the use of a bio-affecting block formed by a process as described herein as a deterrent block to deter or repel aquatic species.

[0042] In a preferred embodiment, the deterred or repelled aquatic species are sharks (Chondrichthyes). The deterrent bio-affecting composition for sharks preferably comprises shark necromones and material comprising shark necromones, portions of shark, biological material originating from shark, and/or putrefied shark tissue extractions.

[0043] In a preferred embodiment, the deterred or repelled aquatic species are cephalopods. The cephalopods are preferably octopus. The deterrent bio affecting composition for cephalopods preferably comprises cephalopod ink.

[0044] The invention further provides for the use of a bio-affecting block formed by a process as described herein as a nutrient and/or attractant block to feed and support the growth and maintenance of aquatic species. A bio-affecting block to feed and support the growth and maintenance of aquatic species, for example, in a tank for a period of time before shipping and/or distribution, would comprise both attractants and nutrients in sufficient amounts to feed the aquatic species.

[0045] The invention provides for the use of a bio-affecting block formed by a process as described herein comprising at least two of: attractant compositions, nutrient compositions, and deterrent compositions. Preferably, the bio-affecting block as described herein comprises attractant compositions and deterrent compositions, wherein the attractant compositions are for attracting decapods, for example, decapod crustaceans comprising lobster, and the deterrent compositions are for deterring sharks and/or cephalopods, for example octopus.

[0046] The invention further provides a process of manufacturing a bio affecting block formed by a process as described herein.

Brief Description of Figures [0047] The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1. Photograph of two blocks of the invention. The left block (A) before being placed in water. The right block (B) after 4 days in a lobster trap in a marine environment.

Figure 2. Photograph of a block of the invention after 96 hours in seawater.

Figure 3. Photograph of three blocks of the invention. The left block (A) freshly made and before being placed in water. The middle block (B) after being submerged in seawater for 24 hours without grazing by aquatic organisms. The right block (C) after being submerged in seawater for 96 hours without grazing by aquatic organisms.

Figure 4. Photograph of two blocks of the invention formed using gel-strips in the alternative embodiment. The left block (A) before being placed in water. The right block (B) after 48 hours in a lobster trap in a marine environment with grazing by aquatic organisms

Figure 5. Photograph of two blocks of the invention. The left block (A) and the right block (B) after being immersed for 60 hours in a trap with grazing by lobsters.

Figure 6. Photograph of two blocks of the invention. The left block (A) before being placed in water in whole. The right block (B) before being placed in water and cut in half.

Figure 7. Photograph of (A) a cross sectional slice of a (B) cylindrical block of the invention.

Figure 8. Photograph of a lobster trap with a cylindrical block of the invention suspended in the trap by a rope through the hole in the block. Description of Preferred Embodiments

[0048] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in the specification, individually or collectively and any and all combinations or any two or more of the steps or features.

[0049] The present invention is not to be limited in scope by the specific embodiments described herein, which are intended for the purpose of exemplification only. Functionally equivalent products, compositions and methods are clearly within the scope of the invention as described herein.

[0050] Other definitions for selected terms used herein may be found within the detailed description of the invention and apply throughout. Unless otherwise defined, all other scientific and technical terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the invention belongs.

[0051] It will be appreciated that the indefinite articles “a” and “an” are not to be read as a singular indefinite articles or as otherwise excluding more than one or more than a single subject to which the indefinite article refers. For example, an emulsifiable concentrate includes one emulsifiable concentrate, one or more emulsifiable concentrates, and a plurality of emulsifiable concentrates.

[0052] Features of the invention will now be discussed with reference to the following preferred embodiments.

[0053] In a preferred embodiment, the process of the invention can be considered in terms of (1 ) preparation and encapsulation of a bio-affecting composition, and (2) formation of a block comprising the encapsulated bio affecting composition that degrades slowly when placed in water, the block for use as an attractant and/or deterrent for specific aquatic species. [0054] Bio-affecting compositions that may be encapsulated by the process of the invention include attractants for forming a ‘bait block’ for use in attracting aquatic species including decapods. Alternatively, the bio-affecting compositions may comprise deterrents for forming a ‘deterrent block’ for deterring or repelling aquatic species, for example, sharks when the deterrents comprise shark necromones, or octopus when the deterrents comprise cephalopods ink. Preferred processes of encapsulating the bio-affecting compositions and creation of bait blocks and deterrent blocks are detailed as follows.

[0055] Part 1: Preparation and encapsulation of Bio-affecting compositions

[0056] Preparation and encapsulation of attractants for inclusion in bait blocks

[0057] Attractants that may be used in the bait blocks of the invention may be obtained from a variety of sources. In selecting these sources, it is important to note that the sensory systems of most decapod crustaceans are considerably more sensitive to free amino acids than raw proteins. Consequently, the attractants to be used preferably have a preponderance of free amino acids.

[0058] Examples of attractants that may be used include those obtained as: a. purified amino acids, for example, available from industrial and animal husbandry suppliers; b. broad-spectrum mixes of amino acids available as hydrolysed fish products; and c. products derived from microbial and algal preparations used in other industries, including aquaculture feeds.

[0059] Regardless of the source of the attractants or the form they are in, for example, as liquids, solids or powders, the attractants comprise complex mixes of soluble and reactive chemicals. Consequently, they can interfere with the chemistry of the setting of the hydrated calcium sulphate hemi-hydrate when forming a bait block. [0060] To address this problem, in a preferred embodiment, matrix encapsulation is used to incorporate the soluble amino acids and other products into the wet calcium sulphate hemi-hydrate paste, in a form that will not interfere with the setting chemistry; but still be soluble and functional as mobile, leachable attractants in the immersed trap setting.

[0061] Process

1 . One or more types of attractants selected for use in the bait blocks of the invention are preferably obtained in powder and/or liquid forms of the raw form of the attractants.

2. Attractants in the form of powders are added to water to form a paste creating an excipient mix.

3. Liquid attractants may be added to the paste or used to form the paste, that is instead of, or in addition to the water.

4. The levels of liquids and/or water added to the one or more powders are carefully controlled or may be added gradually until a substantially firm paste is produced.

5. Other ingredients may be added to the excipient mix comprising: a. Inert fillers, for example, CaS04, kaolin or other clays, lime, starch, flours, cellulose powders, cellulose fibres. b. Protective and viscosity modifying products for example, hydrocolloids and polymers, natural and synthetic gums including food grade gums, guar gum, xanthan gum, pullulan, carboxymethyl cellulose. Also, polyvinyl pyrrolidone, polyvinyl acetate, and polyethylene glycol. c. Stabilising sugars including sorbitol, mannitol, trehalose d. Preservatives, such as sodium benzoate i. Preservatives are preferably added to the encapsulated attractant which places them with the organic materials listed above that are likely to be subject to microbial attack. This also reduces the quantity required for treating this smaller, encapsulated organic component and maintaining the minimum active concentration for efficacy.

6. The viscosity of the paste is adjusted using water and/or the other ingredients to facilitate extrusion through a metal die.

7. The paste is extruded through a metal die having hole diameters of between approximately 0.1 mm to 10 mm, more preferably between approximately 0.5 mm and 5 mm, even more preferably between approximately 0.5 mm and 2 mm.

8. The extrusions of paste are placed onto drying racks and dried, for example, drum dried. Diameters of the dried extrusions may be between approximately 0.1 mm to 10 mm, more preferably between approximately 0.5 mm and 5 mm, even more preferably between approximately 0.5 mm and 2 mm.

9. Once dry or firm to touch the dried extrusions of newly formed matrix encapsulated attractants can be stored ready for use, or used directly in the Part 2 process of forming a bait block according to the invention.

10. Dried extrusions of matrix encapsulated attractants may be cut or broken to produce smaller pieces or particles to form a dry, or semi- dry, stable state powder or granule for inclusion in the blocks during wet paste mixing phase detailed below.

[0062] The matrix encapsulation process encapsulates the attractants in a dry or semi-dry form. For example, the outer surface of the extrusion may be dried but some moisture may be maintained within the extrusion.

[0063] Preparation and encapsulation of deterrents for inclusion in deterrent blocks [0064] Shark Deterrents

[0065] Shark necromones are a group of soluble chemicals, amino acids and other breakdown products associated with decomposing shark bodies. These chemicals have been shown to deter sharks from an area of activity and to stop feeding activities. A problem with the effective use of this technology has been the difficulty in maintaining effective concentrations of these chemicals in an area of interest in an aquatic environment. The deterrent block of the invention enables such deterrent chemicals to be deployed and maintained in the water adjacent the deterrent block at such concentrations to deter affected shark species.

[0066] Potential applications of shark deterrent blocks of the invention may comprise, amongst others, for use in sea cage fish farms, recreational fishing, by divers, and prevention of shark entanglements in netted swimming areas.

[0067] The process for encapsulating deterrent chemicals and compositions comprising necromones for forming shark deterrent blocks according to the invention is the same process as described above in Part 1 (with the attractants replaced with deterrents).

[0068] Octopus Deterrents

[0069] Octopus are predators of lobsters and can cause significant losses to lobster catches with 10% losses reported by the South Australian lobster fishery at certain parts of season and sites. Octopus are cephalopods, and sophisticated and intelligent invertebrates. Many cephalopods including squid and octopus use inks as predator defences and deterrents. These inks are also reported to be active as alarm signals for conspecifics.

[0070] Ink from cephalopod species may therefore be used as deterrents to octopus and the present invention further comprises deterrent blocks for octopus that comprise encapsulated cephalopod ink. These inks can be sourced from commercial octopus fishers. The process of encapsulation of cephalopod ink for forming a block of the invention is the same process as described above in Part 1. [0071 ] The type of block of the invention comprising encapsulated cephalopod ink will depend on its overall purpose. That is, in one embodiment cephalopod ink may be encapsulated together with decapod crustaceans attractants using the encapsulation process above to form for example, a bait block for attracting lobster into a lobster trap, but also deter foraging or inquisitive octopus from entering that trap and eating the captured lobster. In a second embodiment, a bait block may have (i) individually encapsulated cephalopod ink, and (ii) individually encapsulated decapod crustaceans attractants embedded in the same block. Alternatively, in a third embodiment, a bait block comprising encapsulated decapod crustaceans attractants may be used in combination with a deterrent block comprising encapsulated cephalopod ink, for example, where both bait block and deterrent block are placed in or around a lobster trap.

[0072] The outcome from all three of these embodiments is potentially an increase in caught lobsters maintained in the lobster trap until trap recovery from the slow release from the bait block of attractant compositions, while minimising catch loss from octopus.

[0073] In another preferred embodiment, other nutritional compositions may also be encapsulated (with or without those already discussed above) that can supplement nutritional and caloric value of the block. These nutritional compositions could include fish meal, soy meal, other legume and grain products. This would provide considerable benefit for use in, for example, long duration set trapping systems and also for facilities holding live lobsters. Thus, blocks comprising these encapsulated nutritional compositions could keep populations of lobsters and other crustaceans alive supplying protein and energy in a slow release, non-polluting matrix.

[0074] Gel-based Portions

[0075] In an alternative, preferred embodiment, gel-based portions are formed from the excipient containing paste following step 5 in the above described process.

[0076] Preferably the paste comprises hydrocolloids and the paste can be dried until a semi-dry leathery ‘gel-like’ texture is achieved. Drying can be improved by slicing the drying paste into portions of various preferred shapes, for example, thin ‘gel’ strips or pieces. The dried gel-based portions are preferably sliced into strips having dimensions of approximately 2 mm to 6 mm thickness, and 10 mm to 50 mm length.

[0077] The gel-based portions comprise the encapsulated attractant and food base. They have advantages of water stability, and do not swell and expand in the wet Plaster of Paris mix. They are attractive to crustaceans and supply an important gustatory feedback to target animals. The gel-based portions are then added to the wet gypsum mix at step 5 of Part 2 below.

[0078] Part 2: Preparation of Block

[0079] Calcium sulphate hemi-hydrate which is also referred to as Plaster of Paris or casting plaster, is used to produce blocks of water stable bait and/or deterrent blocks of the invention comprising encapsulated bio-affecting compositions.

[0080] Process

1 . The water to calcium sulphate hemi-hydrate ratio is critical to ensure that the mixed paste has correct properties for pumping, moulding and setting a. Ratio is preferably in the range 0.2 to 1 .0 with respect to calcium sulphate hemi-hydrate dry weight. Therefore, this involves mixing 0.2 to 1 .0 L of water per kg of calcium sulphate hemi- hydrate dry weight. b. Additives can be included into the calcium sulphate hemi-hydrate and water mix that control the: i. setting speed; ii. un-set viscosity; and iii. Hardness and dissolution rate of final dried block.

2. In a mixing vessel, add measured quantity of clean water. a. The water needs to be of a sufficient quality with low levels of salts and/or other contaminants. Water with high salts or other contaminants can interfere with the setting chemistry of the calcium sulphate. Generally, potable quality water is adequate. Add retarding chemicals, if required, to the water in the mixing vessel and dissolve. a. The chemical added in this preferred embodiment is tartaric acid powder at 0.5% of the calcium sulphate hemi-hydrate dry weight. b. The role of the retarding chemicals is to delay the setting of the calcium sulphate by approximately 30 minutes. c. Adding tartaric acid at a higher dose than 0.5% w/w will further delay the setting of the calcium sulphate. d. A range of other food grade chemicals are known to delay setting, for example sodium tri polyphosphate; and these can also be used together or individually as retarding chemicals. Add the measured weight of calcium sulphate hemi-hydrate to the mixing vessel. Add measured weight of the encapsulated attractant and/or deterrent from Part 1. to the mixing vessel. Other additives may be added to manipulate desired properties of final block, for example: a. Hydrocolloids; b. Sugars; c. Preservatives, for example sodium benzoate; and/or d. Inert or reactive powders or fibres as fillers or providing functional properties. Immediately commence mixing the ingredients in the mixing vessel. As soon as a substantially homogenous mixture of ingredients is created, the substantially homogenous mixture is pumped into moulds and allowed to set. a. Suitable pumping equipment is available in a range of designs for use in pumping high viscosity pastes, for example: i. Progressive cavity pumps ii. Peristaltic pumps iii. Lobe pumps iv. Auger style extruders b. The moulds are configured to create the final block shape and dimensions as desired which benefits, for example, storage, placement and to fit within a bait holder of a trap. c. Alternatively, moulds can be used for forming larger blocks that when at least partially set can be cut into smaller blocks of a desired suitable size and shape for use.

9. Cut or moulded blocks are then dried. This is to ensure that ‘water activity’ of stored block is sufficiently low to prevent microbial growth on and within the block.

10. Block dimensions a. Physical dimensions of the resulting block of the invention will depend on requirements of the fishery: trap size, desired bait/deterrent persistence, requirement to be a food source and other factors. b. A typical block size would be in range of 200 to 3000 g, more preferably approximately 2000 g, with physical dimensions of approximately 50 mm x100 mm x 100 mm to approximately 120 mm x 120 mm x 200 mm.

[0081 ] The resulting moulded block of the invention may comprise a variety of different shapes. In a preferred embodiment, the block of the invention comprises a shape that is substantially a cube, or rectangular prism with regular or irregular sides. In another preferred embodiment, the shape of the block of the invention comprises a cylinder, or more preferably a cylinder comprising an axial aperture, i.e. a hole through the centre through which the block may be secured to a lobster trap, for example, by a rope or rod.

[0082] The encapsulated bio-affecting compositions comprising attractants and/or deterrents prepared by the process described above in Part 1 are included into the mixture during preparation of the calcium sulphate hemi- hydrate paste as described above in step 5 of Part 2. The encapsulation of the bio-affecting compositions prevents their substantial leaching into the calcium sulphate hemi-hydrate paste which would adversely affect the setting chemistry of the block during the manufacturing process, which in turn would cause the block to dissolve faster when in use. This encapsulation process where the bio affecting composition is mixed and concentrated into a dry or semi-dry product forms a distinct and separate phase. This phase separates it from the bulk of the wet phase calcium sulphate setting chemistry required to form a stable matrix of the bait.

[0083] Unencapsulated bio-affecting compositions would also result in faster degradation of the block during normal use due to solubilisation of the calcium sulphate from within the block from the moist (unencapsulated) internally located bio-affecting compositions. Thus, with the calcium sulphate being broken down from the inside and outside, the block will break down considerably faster than a block of the invention comprising encapsulated bio-affecting compositions which substantially prevent these compositions, or at least moisture in them, breaking down the calcium sulphate structure from the inside out.

[0084] While the encapsulation process is designed to allow the release of soluble bio-affecting compositions during use when the bait or deterrent block of the invention is immersed in water, the encapsulation ensures that the rate of release of the bio-affecting compositions is delayed sufficiently until the encapsulated bio-affecting compositions is in contact with water from the surrounding environment as the calcium sulphate breaks down during normal use. Thus, overall the degradation of a block of the invention is slow.

[0085] Matrix encapsulation is particularly suited to relatively larger volumes of bio-affecting compositions comprising attractants or nutritional products, for example fish meals or soy or other high protein meals. Lower volume, high value attractants and/or deterrents can also be encapsulated using other matrix encapsulation technologies, for example, spray drying, fluidised bed drying and granulation techniques.

[0086] In this respect, in other preferred embodiments, processes of encapsulation of bio-affecting compositions for use in the blocks of the invention may also comprise:

Spray drying • Spinning disc

• Fluidised bed (drying, granulation, coating)

• Extrusion

• Coextrusion

• Powder granulation

[0087] Part 3: Top Dressing

[0088] The process of the invention as described herein is designed to delay in-water degradation of a block of the invention comprising encapsulated bio affecting compositions, than if those same bio-affecting compositions were not encapsulated. This generally results in a delay in the release of bio-affecting molecules from the block of the invention immediately after placing in water during normal use.

[0089] This delay may be advantageous, for example when traps are deployed in daylight but are for the attraction of nocturnal species. However, there may be a need for more rapid release of bio-affecting attractants/deterrents which may be potentially hampered by the delay.

[0090] In a preferred embodiment, the solution to avoiding this delay is the additional step in the process of the invention referred to as ‘top-dressing’. Top dressing comprises applying an aqueous mix of attractant and/or deterrent onto the dried or semi-dried manufactured bait block at the end of the process of Part 2. The aqueous mix may be applied to the block by spraying, coating, or another method. The top-dressed block would then be dried prior to storage or use.

[0091] When the block is placed in water, the bio-affecting attractant and/or deterrent chemicals, molecules, substances, or compositions would readily and rapidly detach or leach from the outer surface of the porous bait block to which it was applied. This would provide an almost immediate effect of releasing the attractants and/or deterrents into the surrounding water. A more progressive and sustained release of dissolving bio-affecting compositions would then occur over time as the block gradually degrades/dissolves during normal use in water. [0092] Therefore, if for example, shark deterrents were to be used and needed immediate effect, top-dressing with necromones in solution would allow quick dissolution in water to have an immediate effect of deterring sharks soon after the block is placed in water. This could, for example, be useful for abalone divers in South Australia who spend considerable amounts of time under the water where large sharks are also found. The effect of the deterrents in the top dressing would have effect from when the diver enters the water, and continued release as the block gradually degrades. The diver could dry out the remains of the block if only partially dissolved during the dive and store until the next dive. Therefore, such a block could provide long term use whether alone or in combination with another shark-deterrent device.

[0093] Coating of Pre-formed Pellets

[0094] In an alternative embodiment, liquid or an aqueous mix of attractant may be applied to dried pellets, for example, stock feed pellets. In this embodiment, a solution comprising, for example, hydrolysates, dissolved amino acids and other attractants and mixtures thereof, are applied to stock feed pellets of approximately 3 mm to 6 mm in diameter by 5 mm to 15 mm in length. However, the specific size of the pellets is not critical.

[0095] The application of solution may be at approximately 20%, i.e. 200 g liquid to 1000 g of pellet. This process can be repeated after drying or semi drying to increase amount of attractant dried onto the surface of the pellets. Coated pellets are dried for storage and before use.

[0096] The attractant solution may also comprise hydrocolloids to improve resilience and water stability of the resulting attractant pellets.

[0097] Use of a Bait Block

[0098] A bait block comprising encapsulated fresh dried and stabilised fish paste as attractants was tested in lobster traps in the marine environment. Figure 1 shows the original manufactured block on the left (A) wherein encapsulated composition appears as dark discolorations and imperfections on the white cut surface of the block. The block on the right (B) shows the level of degradation after 4 days in seawater in a lobster trap wherein encapsulated composition is visible as brown lumps.

[0099] Figure 2 shows a block of the invention which has been placed in seawater for 96 hours to avoid any influence of grazing organisms such as lobsters and others. The gypsum (calcium sulphate hemi-hydrate) has been dissolving slowly from the outside surface inwards exposing the encapsulated material (fresh dried and stabilised fish paste) progressively.

[00100] Figure 3 shows another example of a block of the invention which has been placed in seawater for 96 hours in the absence of grazing organisms to observe degradation and dissolving of the block. Photographs were taken before submersion in water (A), and after 24 hours (B) and 96 hours (C). After 96 hours the organic material emanating from the encapsulated attractants can be observed. Also observed, is the lack of dissolving of the block from the inside out due to the encapsulation of the organic materials thereby preventing moisture escaping organic material and dissolving adjacent calcium sulphate.

[00101] The gypsum matrix was shown to have good, solid physical properties, with an acceptable dissolution rate in seawater. Furthermore, the encapsulated material is progressively available on outer surface of the block as block dissolves or is grazed down.

[00102] The composition of the encapsulated material is designed so that it will hydrate slowly once soaked in water, and is then able to leach into water spaces within the calcium sulphate (gypsum) block and then into the aqueous environment around the trap where is can be detected by target animals. The techniques and chemicals used to ensure slow hydration and progressive leaching of the attractant chemicals include the natural and food grade gums, hydrocolloids and polymers, such as starches, guar gum, xanthan gum, pullulan, polyvinyl pyrrolidone, polyvinyl acetate, polyethylene glycol.

[00103] Figure 4 shows a block of the invention comprising gel-based portions in the form of gel strips (A) before being placed into the lobster trap and the ocean, and (B) after being left in a lobster pot placed on the ocean floor for 48 hours. Grazing by lobsters and other marine organisms is evident on the partially dissolved block. Remnants of the encapsulated gel-strips can be seen in the degraded gypsum block after being consumed by organisms and/or dissolved into the surrounding water.

[00104] Blocks of the invention after being immersed in seawater in lobster pots for 60 hours are shown in Figure 5. Encapsulated attractant inclusions have been mostly removed by grazing lobsters and other marine organisms. The dissolution of the Plaster of Paris matrix over the 60 hours progressively exposed more encapsulated attractant and food pieces. Active scraping and tearing of matrix by dactyls of lobsters is also evident on the surface of the blocks which also assist in the loss of the Plaster of Paris matrix. In this respect, a 50% loss of block mass is expected over this time period.

[00105] Figure 6 shows blocks of the invention (A) in full, and (B) halved before use. The cut block (B) shows the internal distribution of the encapsulated food and attractant products within the block of the invention. It is clear that the encapsulation of the food and other products in the block of the invention prevents spread of moisture into the surrounding Plaster of Paris matrix (which would break down the block from the inside out during storage and would be visible within the cut block and which it is not.

[001061 Trials

[001071 Tank Trials

[00108] Tank trials were undertaken with wild caught, acclimated spiny rock lobster of the species Panulirus cygnus.

[00109] Choice trials were conducted in full tanks of dimensions 2 m x 1 m where the spiny rock lobster had a choice of gypsum bait or fresh whole mussels to feed on.

[00110] Data from the tank trials conducted by researchers at the University of Western Australia showed that while there were more mussel choices, the lobsters also selected gypsum baits. Mussel is widely accepted as a highly attractive food for lobsters, which indicated that this result was strong evidence of efficacy for gypsum baits according to the present invention.

[00111 ] Table 1 . Tank choice trials.

[001121 Ocean Trials

[00113] Trials were next conducted by fishermen in deep water in their usual cray traps with their standard fish baits in four traps and the gypsum bait of the invention used in another four traps. The number of lobsters caught in the traps over the same time period and location was compared. The results are shown in Table 2 and the gypsum baits of the invention showed evidence on their surface of ingestion and grazing by lobsters and deep-sea crabs. A larger number of lobsters were caught in traps using the gypsum baits of the invention that traps using fish baits. No statistical data.

[00114] Table 2. Trap trials in deep water.

[00115] Advantages [00116] Advantages of the process of the invention and the resulting blocks comprising encapsulated bio-affecting compositions include the following.

[00117] The chemical interactions between bio-affecting compositions and excipients within the calcium sulphate hemi-hydrate matrix are minimised. This means the physical properties of the matrix can be optimised to suit the application.

[00118] The process of the invention allows a wide range of attractant and/or deterrent materials and nutrient products to be used to form the bio-affecting compositions. This includes refined and unrefined (raw) sources of proteins, amino acids and other chemicals from marine and non-marine origins, and high protein legume and grain meals and excipients. Also, fish products, including enzyme hydrolysates, fermented products, fish meals, fish processing by products, and macerated fish material.

[00119] It removes the constraint of low rates of inclusion of the bio-affecting compositions and nutrient additives into the stable calcium sulphate hemi- hydrate matrix. This changes from an inclusion rate of only a few percent with non-encapsulated product, to approximately 50% when utilising the encapsulation process of the invention.

[00120] It also allows for inclusion of products that can supplement nutritional and caloric value of the block product. These products could include fish meal, soy meal, other legume and grain products. This application would be in long duration set trapping systems and for facilities holding live lobsters. This system supplies protein and energy to lobsters in a slow release, non-polluting matrix.

[00121] The heterogenous distribution of encapsulated attractant and nutrient particles in the bait or feed block is an efficient method to enhance efficacy and efficiency of valuable components. It is consistent with modern research on taste and sensory physiology in mammals, where heterogenous distribution of flavour components is used to enhance detection of flavour components, while reducing inclusion rates of these. Animal senses are better at detecting concentration than quantity; and also, grazing and predatory animals are well adapted to locating and using dispersed food items, even on small scales. [00122] Alternate Block Shapes

[00123] The block of the invention provides a slow release of soluble attractant molecules. The block of the invention also supplies a heterogeneously distributed food supply within the inedible calcium sulphate matrix. Further, the crustaceans are able and motivated to detect and extract dispersed lumps of food from the gypsum matrix.

[00124] Bait blocks of the invention rely on leaching of soluble attractant molecules, and targeted scraping by lobster or other crustaceans, to access and ingest particulate/solid attractant inclusions within the bulk inorganic matrix. These two features are strongly affected by surface area and access to the bait for target animals.

[00125] Improved results have been achieved when bait blocks of the invention are situated in the main trap zone where the animals have direct physical access to the bait. In traditional trapping systems the baits are placed into mesh bait baskets, which separate animals from direct access to the bait. To compensate for increased access and consequent grazing, the bait needs to be larger. A 1500 g to 2000 g bait is useful size for biological and logistical reasons, but larger sizes can be used where grazing pressure is high due to high animal densities, or there is requirement for longer set times.

[00126] To ensure shelf stable properties of the complete bait block of the invention, the formed bait needs to be dried to a stage where water activity through bulk of bait is sufficiently low as to inhibit microbial activity. Even with addition of food preservatives they need to be dried sufficiently.

[00127] The large size and relatively low surface area of bait blocks of the invention imposes a constraint on the rate of drying to achieve this stable state. Extended time required for drying is a risk for negative microbial growth on organic material within the gypsum bait. Thus, a balance between block size and drying time to minimise microbial growth had to be achieved.

[00128] Cylindrical, square or rectangular shape for bait blocks of the invention of approximately 2000 g size is preferred in terms of the moulding and end use requirements. They also ensure that the bait block has physical strength and size to persist within the trap zone for the required period of the trap set. Bait shapes with flattened dimensions with high surface area to volume rations are often fragile and disintegrate too quickly for the desired set time.

[00129] However, these larger bait blocks have relatively low surface area which restricts water loss during drying, because of slow movement of water from inner parts of the bait to outer surface from where the water can evaporate. A solution to this issue was to mould the bait block with a large hole or aperture, preferably circular to give an annular structure. This significantly increased the drying rate, by reducing the distance for water to move to external surface for evaporation. This can also increase the surface area for leaching of soluble attractant molecules. This central hole is also a useful means with which to attach the bait block within the trap contained area.

[00130] Figure 7 shows (A) a cross sectional slice of (B) a cylindrical approximately 2000 g bait block of the invention with an open annular structure.

[00131] Figure 8 shows the cylindrical bait block of the invention suspended with a lobster trap by a rope through the hole for ease of access by the lobsters. Alternatively, the bait may be placed over a fixed spike in the lobster trap which is aligned within the hole of the bait block to maintain it in place.

Claims (34)

The Claims Defining the Invention are as Follows

1. A process of forming a bio-affecting block for use in an aquatic environment to attract, deter and/or feed aquatic species, the process comprising the steps: encapsulation of one or more bio-affecting compositions; combining the encapsulated bio-affecting compositions with an inert medium and a solvent to form a mixture; and drying the mixture to form a block; wherein when the block is placed in water, it will gradually dissolve and release the encapsulated bio-affecting compositions into the surrounding water.

2. A process according to claim 1 , wherein the bio-affecting compositions comprise attractants, deterrents, and/or nutrients for aquatic species.

3. A process according to claim 1 or claim 2, wherein the step of encapsulation of the one or more bio-affecting compositions comprises the process of matrix encapsulation.

4. A process according to any one of the preceding claims, wherein the step of encapsulation comprises a step of mixing and concentrating bio affecting compositions to form an aqueous paste.

5. A process according to claim 4, wherein the bio-affecting compositions are in powder and/or liquid forms of the raw form of the bio-affecting compositions.

6. A process according to claim 4 or claim 5, wherein excipients are added to the bio-affecting compositions to form the aqueous paste.

7. A process according to claim 6, wherein the excipients comprise one or more from the group comprising: water or another solvent; inert fillers comprising CaS04, kaolin or other clays, lime, starch, flours, cellulose powders, cellulose fibres; protective and viscosity modifying products comprising hydrocolloids, natural and synthetic gums such as guar gum, xanthan gum, pullulan, carboxymethyl cellulose; stabilising sugars comprising sorbitol, mannitol, trehalose; preservatives compromising sodium benzoate.

8. A process according to claim 7, wherein the excipients adjust the viscosity of the aqueous paste to form a substantially firm aqueous paste.

9. A process according to claim 8, wherein the paste comprises hydrocolloids and is dried to form thin gel-based portions from production of a semi-dry ‘gel-like’ texture.

10. A process according to any one of claims 4 to 8, wherein the aqueous paste is extruded through a die to form extrusions of aqueous paste.

11. A process according to claim 10, wherein the die holes through which the aqueous paste is extruded are between approximately 0.5 mm to 2.0 mm.

12. A process according to claim 10 or claim 11 , wherein the extrusions of aqueous paste are dried forming encapsulated bio-affecting compositions.

13. A process according to claim 12, wherein the encapsulated bio affecting compositions comprising dried extrusions of paste are broken into smaller portions or particles.

14. A process according to any one of the preceding claims, wherein the solvent is water.

15. A process according to any one of the preceding claims, wherein the inert medium is calcium sulphate hemi-hydrate.

16. A process according to claim 15, wherein the ratio is approximately 0.2 to 1.0 L of water per kg calcium sulphate hemi-hydrate dry weight.

17. A process according to claim 15 or claim 16, wherein dried portions or particles or gel strips of encapsulated bio-affecting compositions are added to the water and calcium sulphate hemi-hydrate mix and combined to form the mixture.

18. A process according to claim 17, wherein excipients are added to the mixture which assist to control the (i) setting speed, (ii) un-set viscosity, and/or (iii) hardness and dissolution rate of the block.

19. A process according to claim 18, wherein the excipients comprise one or more selected from the group comprising: retarding chemicals; hydrocolloids; sugars; preservatives comprising sodium benzoate; inert or reactive powders or fibres as fillers or providing functional properties.

20. A process according to claim 19, wherein the retarding chemicals comprise either or both of tartaric acid and sodium tri polyphosphate.

21. A process according to claim 20, wherein the tartaric acid is added in powder form at 0.5% by weight of the calcium sulphate hemi-hydrate.

22. A process according to any one of claims 17 to 21 , wherein the mixture is substantially homogenous.

23. A process according to any one of claims 17 to 22, wherein a mould for forming a block is filled with the mixture which sets in the mould.

24. A process according to claim 23, wherein the mixture is pumped into the mould.

25. A process according to claim 24, wherein the pump is suitable for pumping high viscosity pastes.

26. A process according to claim 23 or claim 24, wherein the dimensions of the mould are between approximately 50 mm x 100 mm x 100 mm and 120 mm x 120 mm x 120 mm.

27. A process according to any one of claims 23 to 26, wherein once the mixture has set, the formed block is removed from the mould and dried.

28. A process according to claim 27, wherein the block comprises a shape that is substantially a cube, rectangular prism, cylinder, or cylinder comprising an aperture.

29. A process according to any one of the preceding claims, wherein bio affecting compositions are applied to the outer surface of the dried block.

30. Use of a bio-affecting block formed by a process according to any one of claims 1 to 29 as a bait block to attract aquatic species.

31. Use of a bio-affecting block according to claim 30, wherein the aquatic species are decapods.

32. Use of a bio-affecting block formed by a process according to any one of claims 1 to 29 as a deterrent block to repel aquatic species.

33. Use of a bio-affecting block according to claim 32, wherein the aquatic species are sharks and the bio-affecting compositions comprises shark necromones and material comprising shark necromones, portions of shark, biological material originating from shark, and/or putrefied shark tissue extractions.

34. Use of a bio-affecting block according to claim 32, wherein the aquatic species are octopus and the bio-affecting compositions comprises cephalopod ink.