In the midst of the threats of hunting and pollution, whales (and other cetaceans) also have to face the ongoing threat of being victim to bycatch; that is the incidental entrapment of these mammals in the fishing industry’s equipment (usually nets, but this equipment can include fishing lines and hooks too). Once caught, the whales cannot escape the indiscriminate grasp of the nets.
Unable to reach the surface for air, they soon drown. It is important to note that, while this leads to many deaths amongst cetaceans, this is not intentional and is, therefore, not a form of whale hunting.
The incidences of wales being caught is happening more and more frequently thanks to the fishing industry’s increased reach and demand.
The types of nets used include gillnets (anchored to the ocean floor and allowed to stand vertically, creating a wall of netting), trawl nets (huge nets that are pulled through the water, trapping anything in their path), purse seines (a dragnet that hangs vertically and can be closed to trap the fish and other animals by means of a drawstring), beach seines (simply a net that is operated from the shore) and driftnets (nets are allowed to float vertically at the surface of the water. Gillnets are the most common fishing tools that currently endanger whales, dolphins and other marine mammals.
A large whale may be strong enough to continue swimming through the net. This means that it does not suffocate. Still, the nets damage and injure the whales, which could cause major wounds that become infected, or permanent physical damage. Many large whale species bear the scars of their entrapment. If the net becomes tangled up in the mouth of the whale, it is likely to starve to death or choke.
There are a number of efforts underway to reduce bycatch in an attempt to protect the marine mammals. These include audible deterrents, which involves using sounds, such as ‘pings’, to scare away the cetaceans. While effective, these carry their own set of risks. Implementing stricter fishing regulations and management is another effort to control the industry and protect the natural inhabitants of the waters. Having on-board observers has also been proposed, so that they are able to watch the water and avoid pods of whales. They are also able to keep an eye on the nets and take action if a whale or dolphin becomes entangled. This is not a fool-proof measure, though.
As civilians and consumers, there are a few steps that we are also able to take to reduce the threat of bycatch to whales, porpoises and other marine mammals. We can restrict our purchasing of tuna and canned fish to those with a dolphin-friendly or dolphin-safe label, only buy seafood that is sustainable, only support restaurants and suppliers that do the same, and raise the awareness of others (even on an individual level).
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