Fishery Bycatch Jeopardizes Indian Horseshoe Crab Tachypleus gigas Along the Northeast Coast of Odisha, India

Anthropogenic activities influence the survival and reproduction of horseshoe crabs in their marine-associated habitats. On the northeast coast of Odisha, India, a large number of them die every year. The use of fishing gear has been identified as the major cause for their mortality. A total of 6546 specimens of entangled T. gigas were recorded in discarded fishing nets from different parts of the Balasore coast from March 2017 to February 2019. The most numerous entangled specimens were recorded during the winter season. Occurrences of stranded horseshoe crabs on the beach were also evident between the years 2018 and 2019, but with decreasing incidences from 4169 in 2018 to 2337 individuals in 2019. A total of 1408 live horseshoe crab specimens out of 6546 that were entangled with discarded fishing nets were successfully rehabilitated and released after removing them from nets and nylon threads. This study aims to control and gradually reduce this phenomenon by working with consortiums of fishermen and the public to create a bycatch awareness campaign. Owing to the overlap of ubiquitous small-scale fisheries with newly documented high-use areas in coastal waters worldwide, our case study suggests that present small-scale fisheries may be among the prime threats to horseshoe crabs. Future research is urgently needed to quantify the bycatch numbers worldwide that are purportedly caused by small-scale fisheries. Overall, tandem working with fishermen, the local coastal, and small-scale fishing industries has the potential to provide a crucial solution toward ensuring the safer existence of horseshoe crabs in India.