Grey Nurse Shark Conservation - Causes For Decline

Causes For Decline

Every year, millions of sharks are killed by drift-nets, by-catch, revenge actions, beach protective shark meshing, commercial-, recreational- and spear-fishing. An alternative view is that grey nurse are totally protected and selective methods of fishing such as spear-fishing have no impact on this species. The main risk is from by-catch of indirect methods of line fishing and particularly bottom-set commercial fishing lines targeting wobbegong sharks. The Grey Nurse sharks are particularly vulnerable to these threats due to their late maturation and low breeding success8. They reach sexual maturity at the age of 6–8 years and give birth to 1 or 2 young every second year, thus the population grows very slowly. Furthermore their limited distribution and specific habitats make it difficult for them to migrate to other areas. Beach nets, unfortunately, cause the death of hundreds of shark that are caught in the nets and cannot escape. This also occurs in trawls and fishing nets. Another threat for the sharks is finning. Finning involves cutting the fins of sharks (used for fin-soup) and often it is pregnant female sharks that are caught. The sharks are often thrown back into the ocean, alive without fins. This kind of finning, without using the rest of the shark, has been prohibited by most countries and shark-fishing boats are now strictly controlled by regulatory authorities.