Pollution from recreational fishing, including lines, hooks, weights, nets, and lures made of both plastic and metal materials, can have a significant effect on aquatic species and the environment. A common fishing lure used by recreational anglers is the soft plastic lure (SPL) which is fabricated of plastisol, a blend of polyvinyl chloride (PVC), plasticizers, and phthalates. These lures are non-degradable and can be toxic to marine life if swallowed. SPLs are manufactured using injection molding and can be configured into various shapes and sizes depending on the targeted fish species. If lost or discarded, these lures can be ingested by fish or other aquatic species, leading to issues such as obstruction of the digestive tract causing the formation of gastric bezoars. For these reasons and to keep fish stocks abundant and healthy, the development of more environmentally friendly fishing options is needed. Several attempts have been made to develop biodegradable fishing baits; however, the strength, wear resistance, and water interaction properties of these baits need to be improved.
A few studies have been completed on the swelling properties of SPLs when left in water for an extended period; however, other important lure properties have yet to be characterized. The objectives of this thesis are:
To achieve the first objective, biodegradable lures were manufactured using injection molding, like the production of SPLs, where eight initial optimization runs were designed to determine how the individual ingredients impact both the manufacturing process and the lure properties. Several changes were made to the manufacturing process including the heating method. Originally, a microwave was used to heat the formula; however, this method is not practical if the process was to be scaled-up. For this reason, the heating method was modified by using a convective heating technique where a stainless-steel beaker was elevated in a boiling pot of water.
The second objective was achieved by selecting several important properties for a soft bait lure to be successful. After careful consideration, several tests were chosen to evaluate the lure performance. The properties of biodegradable soft bait fishing lures and SPLs were examined and compared by exploring the strength, swelling, heat resistance, viscosity, and porosity of the baits. Comparison of the results indicated that SPLs showed superior properties compared to the biodegradable lures. More specifically, SPLs showed improved swelling properties, heat resistance ability, and viscosity.
Lastly, to achieve the third objective, a final formula optimization was completed by adding a new ingredient to the formula to improve the performance of the biodegradable lure. Carboxymethyl chitosan, a water-soluble form of chitosan, was added to the lures to attempt to improve the hindering properties, such as the strength, swelling, viscosity, and underwater performance of the baits. The addition of carboxymethyl chitosan showed significant improvement in the strength of the lures after being submerged in water and the underwater performance of the baits.