Global elasmobranch population decline can be largely attributed to anthropogenic impacts such as commercial fishing. As such, reducing bycatch of these animals is a key management objective in many fisheries. Magnetic deterrents such as permanent and rare-earth magnets can deter both pelagic and benthic elasmobranch species. However, the literature is inconsistent and shows varied levels of effectiveness depending on the species and the deterrent. To broaden our understanding of species-specific differences in deterrent effectiveness, this study assessed the efficacy of a rare-earth magnet to deter four benthic elasmobranchs under laboratory conditions: Port Jackson shark (Heterodontus portusjacksoni; n = 10), epaulette shark (Hemiscyllium ocellatum; n = 8), eastern fiddler ray (Trygonorrhina fasciata; n = 10), and the blue spotted mask ray (Neotrygon kuhlii; n = 7). After evaluating the behavioural response of the four study species in the presence of a N52 neodymium magnet and a control in 207 trials, the neodymium magnet did not effectively prevent individuals from entering an experimental compartment. The magnet only had a minor deterrent effect, slightly reducing the proportion of successful attempts at entry through the door and over the neodymium magnet (control: 0.94 ± 0.23; neodymium magnet: 0.74 ± 0.3; mean ± standard deviation). We hypothesised this was a result of species-specific biological and behavioural factors that reduce the effectiveness of magnets as deterrents for these species. Our results suggest fisheries management moves away from trialling magnets as elasmobranch deterrents due to their inconsistent effectiveness, and rather investigate other devices such as those using electrical fields that show greater potential.

全球软骨鱼种群数量下降很大程度上归因于商业捕捞等人为影响。因此，减少这些动物的兼捕是许多渔业的一个关键管理目标。永久磁铁和稀土磁铁等磁性威慑物可以威慑远洋和底栖软骨鱼物种。然而，文献并不一致，并且根据物种和威慑作用显示出不同程度的有效性。为了加深我们对威慑效果中物种特异性差异的理解，本研究评估了稀土磁铁在实验室条件下威慑四种底栖软骨鱼的功效：杰克逊港鲨（Heterodontus portusjacksoni；n = 10）、肩章鲨（Hemiscyllium ocellatum） ; n = 8)、东部提琴魟 ( Trygonorrina fasciata ; n = 10) 和蓝斑面罩魟 ( Neotrygon kuhlii ; n = 7)。在 207 项试验中评估了四个研究物种在 N52 钕磁铁和对照存在的情况下的行为反应后，发现钕磁铁并没有有效阻止个体进入实验隔间。磁铁仅具有较小的威慑作用，略微降低了通过门和通过钕磁铁进入的成功尝试的比例（对照：0.94±0.23；钕磁铁：0.74±0.3；平均值±标准差）。我们假设这是物种特异性生物和行为因素的结果，这些因素降低了磁铁对这些物种的威慑作用的有效性。我们的结果表明，渔业管理部门不再尝试使用磁铁作为软骨鱼威慑物，因为它们的效果不一致，而是研究其他设备，例如那些显示出更大潜力的使用电场的设备。