1. Entanglement:
* Gillnets: These are large, vertical nets that hang in the water column. Dolphins can swim into them and become entangled, often by their fins or flukes.
* Driftnets: These nets are long and float on the surface, and are often used for catching tuna and other pelagic fish. Dolphins can become entangled in them, often by their heads or bodies.
* Bottom trawls: These nets are dragged along the seafloor, catching fish and other marine life. Dolphins can become entangled in them, especially if they are swimming close to the bottom.
* Other nets: Dolphins can also become entangled in other types of fishing nets, including purse seines, trammel nets, and even lobster traps.
2. Bycatch:
* Dolphins are sometimes caught as bycatch in fisheries that target other species. This means they are caught unintentionally. For example, dolphins can be caught in tuna purse seines, which are nets that are used to surround schools of tuna.
* Bycatch can occur because dolphins often swim near the same areas as the target fish, making it difficult for fishermen to avoid them.
Consequences of Entanglement:
* Drowning: Dolphins can drown if they become entangled in nets and are unable to reach the surface to breathe.
* Suffocation: Even if they can reach the surface, dolphins can suffocate if their breathing is restricted by the net.
* Injuries: Dolphins can suffer severe injuries from entanglement, including cuts, abrasions, and broken bones.
* Starvation: Dolphins can also die from starvation if they are unable to feed while entangled in a net.
Solutions:
* Fishing Gear Modifications: There are several ways to modify fishing gear to reduce the risk of dolphin entanglement, such as using larger mesh sizes in nets, using acoustic deterrents, and using nets that are designed to release dolphins.
* Fishing Practices: Fishermen can also use techniques that reduce the risk of bycatch, such as avoiding areas where dolphins are known to congregate.
* International Regulations: There are international regulations in place to reduce the risk of dolphin entanglement, but these regulations are not always effective.
It's important to note that entanglement is a major threat to dolphins worldwide. Many organizations are working to reduce the risk of entanglement and bycatch, but more needs to be done to protect these animals.