Sustainable marine bait technology : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Manawatu Campus, Palmerston North, New Zealand. EMBARGOED until 4th July 2028.

Abstract

Longline fishing has emerged as a sustainable alternative to set nets and trawling for targeting rig, reducing bycatch and supporting conservation efforts. Rig (Mustelus lenticulatus) is highly attracted to crustacean-based baits and a frozen crayfish waste stream from Fiordland Lobster Company presents an opportunity to develop an alternative bait. This project formulated a bait consisting of three key components: crayfish mince, a matrix forming agent, and sausage casing. The manufacturing process involved standardised mixing, forming, portioning, and conditioning steps. Before sea trials, the formulated baits underwent a simulated sea trial using an orbital shaker to replicate rough sea conditions. Formulations that remained intact on the hook after six hours of seawater submersion were subjected to texture analysis. Additionally, protein leaching rates were quantified and compared to traditional crayfish leg baits to assess their effectiveness in attracting rig. These tests ensure the bait is durable in longlining operations and its effectiveness in attracting fish. Preliminary sea trials were conducted with test baits, allowing fishers to provide feedback for further refinements before scaling up production to 1,000 test baits per production. The scale-up process utilised small-scale food production equipment adapted for laboratory manufacturing. Official field evaluations compared two different formulated baits against control samples across varied environmental conditions, with results indicating improved catch performance for the new formulated baits. Thus, the developed crayfish sausage baits were more effective than control baits in catching both fish and rig. Future studies can adapt this processing method and materials to other seafood waste streams, potentially leading to a new bait manufacturing industry in New Zealand. This would support the fishing sector, reduce waste, and promote sustainable resource utilisation.