TRAWL - In midwater trawling a cone-shaped net is towed behind a single boat and spread by trawl doors (image), or it can be towed behind two boats (pair trawling) which act as the spreading device. Midwater trawling is relatively benign compared to the damage bottom trawling can inflict on the sea bottom.
Fishing nets are devices made from fibers woven in a grid-like structure. Some fishing nets are also called fish traps, for example fyke nets. Fishing nets are usually meshes formed by knotting a relatively thin thread. Early nets were woven from grasses, flaxes and other fibrous plant material. Later cotton was used. Modern nets are usually made of artificial polyamides like nylon, although nets of organic polyamides such as wool or silk thread were common until recently and are still used.
This is a nylon fishing net with float line attached to small plastic floats.
Nylon is a very strong and durable engineering grade plastic
that is also used to make bearings for machinery, printers and
many more applications. It is not the plastic that is at falut,
it is the way we are using it for fishing.
NET - A trawl is a large net, conical in shape, designed to be towed along the sea bottom. The trawl is pulled through the water by one or more boats, called trawlers or draggers. The activity of pulling the trawl through the water is called trawling or dragging. Bottom trawling results in a lot of bycatch and can damage the sea floor. A single pass along the seafloor can remove 5 to 25% of the seabed life.
SEINE - The purse seine
net is widely used by commercial fishermen, is an evolution of the surround net, which in turn is an evolution of the seine net. A large net is used to surround fish, typically an entire fish school, on all sides. The bottom of the net is then closed by pulling a line arranged like a drawstring used to close the mouth of a purse. This completely traps the fish.
There is a higher chance of bycatch using this fishing method.
NETS IN HISTORY
In Norse mythology the sea giantess Rán uses a fishing net to trap lost sailors. References to fishing nets can also be found in the New Testament. Jesus Christ was reputedly a master in the use of fishing nets. The tough, fibrous inner bark of the pawpaw was used by Native Americans and settlers in the Midwest for making ropes and fishing nets. The archaeological site at León Viejo (1524–1610) has fishing net artifacts including fragments of pottery used as weights for fishing nets.
PROBLEM - From 2000 to 2012, the National Marine Fisheries Service reported an average of 11 large whales entangled in ghost nets every year along the US west coast. From 2002 to 2010, 870 nets were recovered in Washington (state) with over 32,000 marine animals trapped inside. Ghost gear is estimated to account for 10% of all marine litter.
Some commercial fisherman use gillnets that are suspended in the sea by flotation buoys, such as glass floats, along one edge. In this way they can form a vertical wall hundreds of metres long, where any fish within a certain size range can be caught. If not collected by fishermen these nets can continue to catch fish until the weight of the catch exceeds the buoyancy of the floats. The net then sinks, and the fish are devoured by bottom-dwelling crustaceans and other fish. Then the floats pull the net up again and the cycle continues. Given the high-quality synthetics that are used today, the destruction can continue for a long time.
NETS - A sea
turtle is ensnared in this fishing net that has been abandoned
by fishermen. Fishing nets are made
of plastic that is very tough and float around killing marine
wildlife and when they finally sink, cause more harm to ocean
ecosystems. Ghost nets are fishing nets that have been left or lost in the ocean by fishermen. These nets, often nearly invisible in the dim light, can be left tangled on a rocky reef or drifting in the open sea. They can entangle fish, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirds, crabs, and other creatures, including the occasional human diver. Acting as designed, the nets restrict movement, causing starvation, laceration and infection, and suffocation in those that need to return to the surface to breathe.
LINKS & REFERENCE
GLOBAL WASTE PROBLEM - The above views of planet earth as global views show us the Atlantic, Indian and Pacific ocean gyres and estimates of plastic waste in (thousands) numbers of pieces of plastic waste per square kilometer of sea. The Pacific Ocean gyres are held to be the worst at the moment.
This website is provided on a free basis as a public information service. copyright © Cleaner Oceans Foundation Ltd (COFL) (Company No: 4674774) August 2017. Solar Studios, BN271RF, United Kingdom. COFL is a charity without share capital.