Whilst primarily targeting many valuable species of large tuna and swordfish, this fishing gear is responsible for the unintended death of seabirds, sea turtles, sharks, dolphins, sea lions, marlin and sailfish. Research shows that the catch rate for target species is as little as two in every 100 hooks set. Even then, this fishing technique can not discriminate between size and species.
As a result some shark populations have been decimated by 90% and longlines are responsible for the estimated deaths of 40,000 sea turtles and 180,000 seabirds every year.
There are many different variations on trawling techniques and the type of equipment used but as fish stocks continue to decline, fishermen have developed more sophisticated gear that now threatens the very structure of the ocean floor whilst indiscriminately catching everything in its wake.
The most common technique used today is the 'otter' trawl. It encompasses steel doors designed to drag along the seafloor, keeping the mouth of the net open. Each door is attached to the fishing boat by long bridles. The spread between trawl doors can extend to 650 feet. To keep the base of the net on the seabed the footrope is often fixed with heavy, destructive rolling disks and metal or rubber bobbins that enable the gear to bounce over the seafloor. An average flatfish bottom trawl vessel can catch approximately 15 tons of fish in a single haul.
Trawling has devastated an undersea area the size of Europe, removing habitats that have been breeding grounds and refuges for up to 10,000 years.
Instead of respect and awe for the ocean, industry, commerce and individuals the world over continue to regard the enormity of the seas as a suitable hiding place for its waste products.
Daily, 300 million of gallons of sewage - often untreated - are discharged into British coastal waters introducing harmful bacteria and viruses that can cause diseases. Visit Surfers Against Sewage for more details.
Annually, approximately 706 million gallons of oil enters the oceans from a variety of sources including offshore drilling and oil exploration (37 million gallons), oil tanker accidents (62 million gallons), natural seeps (92 million gallons), industry and transport bi-products (137 million gallons) plus ship maintenance and bilge cleaning (363 million gallons).
Nearly half of all oil pollution in the ocean (343 million gallons) makes its way into the oceans from the urban environment through vehicle ownership and maintenance. Even though it is illegal in many countries to dump used engine oil into the drain or elsewhere other than designated receptacles, an enormous number of motorists worldwide continue to flaunt the law, effectively pouring oil directly into the sea. Alarmingly, this ignorant and avoidable behaviour has become one of the single most significant contributors to marine pollution. Visit Oil Care for your nearest oil recycling bank.
Agricultural sewage, fertilisers and pesticides also contribute to higher levels of marine pollution reaching the oceans through run-offs to rivers. Farming chemicals are designed to kill pests and increase the productivity of the land. They have no place in the ocean where, combined with sewage, causes massive nutrient loading in the ocean's ecosystem. High levels of nutrient loading prompts algae blooms, leading to lower levels of dissolved oxygen. In turn, this depletion of oxygen causes the death of many marine organisms.
Marine debris is yet another daunting illustration of corporations' and individual's lack of respect for the aquatic world. Rubbish is jettisoned from boats all over the world with a horrific accumulative effect. Almost completely un-policed, millions of tonnes of sewage and rubbish is discarded into the sea directly from massive cruise liners, fishing vessels and recreational boaters. According to Ocean Conservancy, an average sized cruise liner can produce around 30,000 gallons of sewage per day. In addition, 255,000 gallons of 'grey' water from laundries, showers, sinks and dishwashers are also likely to be dumped at sea on a daily basis. Other discharges include 37,000 gallons of oily bilge water and 15 gallons of toxic waste from services such as dry-cleaning and photo-processing.