BYCATCH

BYCATCH

WHAT A WASTE - Current fishing methods are putting some species at risk as to extinction.

WHAT IS BYCATCH?

Bycatch is the incidental capture of non-target species such as dolphins, marine turtles and seabirds. Even with the latest technology and industry recognition of the harm they are causing, bycatch is still a major problem. Not only does it cause avoidable deaths and injuries, but the fishing methods can be harmful to the marine environments where they are employed.

Some obvious solutions do exist such as modifying fishing gear so that fewer non-target species are caught or can escape, but modern fishing gear is often undetectable by sight to be effective and is extremely strong to be suitable for catching the desired fish species. The problem is that such nets also catch anything else in their path.

NON SELECTIVE NETS

According to the World Wildlife Fund it is estimated that over 300,000 small whales, dolphins, and porpoises die from entanglement in fishing nets each year, making this the single largest cause of mortality for small cetaceans.
Species such as the vaquita from the Gulf of California and Maui’s dolphin from New Zealand face extinction if the threat of unselective fishing gear is not eliminated.

BOTTOM TRAWLING

Industrial trawlers once avoided coral reefs and other rocky regions of the ocean floor because their nets would snag and tear. But the introduction of rockhopper trawls in the 1980s changed this. These trawls are fitted with large rubber tires or rollers that allow the net to pass easily over any rough surface. The largest, with heavy rollers over 75cm in diameter, are very powerful, capable of moving boulders weighing 25 tonnes. Now, most of the ocean floor can be trawled down to a depth of 2,000m.

These trawls - whose use is now widespread - are extremely damaging. In an experiment off Alaska, 55% of cold-water coral damaged by one pass of a trawl had not recovered a year later. Scars up to 4km long have been found in the reefs of the north-east Atlantic Ocean. And in heavily fished areas around coral seamounts off southern Australia, 90% of the surfaces where coral used to grow are now bare rock. When covered with marine life, these seabed areas provide habitat for juvenile fish and other species. Like removing forest, removing this cover decreases the area available for marine species to live and thrive in.

Many species, including those at risk of extinction, are accidentally caught and then thrown back into the sea, often already dead. These collateral losses, known as discards, can reach up to 80% or even 90% of the total catch.

Seabed ecosystems are characterized by exceptional biodiversity. Over the last 25 years, scientific studies have identified very rich marine environments at depths greater than 400 meters, down to 2,000 meters and more. Despite almost complete darkness, strong pressure and very weak currents, a huge number of species can be found in these deep waters.

The scientific community and many NGOs are calling for an international moratorium to protect the seabed from bottom trawling, but government efforts to support this have so far been minimal.

A recent WWF report estimates that bycatch represents 40% of global marine catches, and that in many cases the fish discarded are juveniles. It is easy to grasp what dramatic consequences such devastation has on the ability of a species to reproduce and regenerate stocks.

YOU CAN'T BE SERIOUS - Whoever thought that this method of fishing would be acceptable to the buying public once they found out about the damage, must have been thinking in the dark ages.

CAN BYCATCH BE ELIMINATED?

Total elimination is unlikely but fishing vessels such as the SeaVax are to be equipped with visible and audible deterrents to try and reduce bycatch to acceptable limits. In addition to these measures, the filters to be used on SeaVax are selectively adjustable, where the vessel reads what is ahead and decides what equipment is appropriate for the task in hand.

Information about the harvest is shared for evaluation and if necessary further instructions or even a software may be uploaded by way of update to improve efficiency.

Traditional fishermen are likely to resist the use of such machines that may eventually replace some fishing vessel types, and that creates another problem that a robotic society will have to deal with - in that people will almost certainly have to be paid not to work.

WWF SMART GEAR COMPETITION

The World Wildlife Fund ran a competition to promote the use of selective fishing methods with their International Smart Gear competition between 2004 - 2014. The WWF, in partnership with industry leaders, scientists and fishers, launched the International Smart Gear Competition in 2004. The competition was designed to inspire creative thinkers.

Smart Gear is a call for innovative ideas that have practical applications for fishing “smarter” - for increasing selectivity for target fish species and reducing bycatch. The competition invites submissions of practical, cost-effective solutions to reduce fisheries bycatch, and offers cash prizes totaling $65,000.

WWF SMART GEAR WINNERS:

Special Bycatch Reduction in Tuna Fisheries Prize: Seabird Saver

The SeaBird Saver is an innovative bird deterrent device based on a laser system and optional acoustic stimulus to aggressively deter birds from dangerous fishing areas, ultimately reducing bird bycatch as well as fatalities while optimizing overall catch for fishermen. The two-person team is made up of Ernst Schrijver, marine biologist, and Wouter van Dam, product manager for Dutch company SaveWave.

The SeaBird Saver is comprised of a mountable, flexible laser source and optional sound system; its deterring effect is made possible by a visual stimulus with a discretionary acoustic stimulus add-on—marketed separately but combined together to increase efficacy. The visual stimulus component is produced by a patented laser beam, emitting a beam that is easily widened for both optimal visibility and the reduction of possible retinal damage caused in birds due to the the unlikely event of long-term exposure. The laser beam itself is calibrated with the correct wavelength for bird eye sightability while simultaneously producing the optimal strength to be effective on liquid services. The laser beam and its scattering effect produces a powerful bird deterrent, especially effective during low visibility conditions—dawn, dusk, rain, and fog. Because most marine birds are threatened by the presence of the laser beam dot—understanding it to be an unnatural and unpredictable threat—their intuitive response is to avoid contact and fly away.

2014 Winner: Air Powered Sampling for Purse Seine Fisheries

The 2014 Smart Gear grand prize of $30,000 was awarded to a Norwegian team whose device addresses bycatch in purse seine fisheries. This “Air Powered Sampling for Purse Seine Fisheries,” allows fishers to check the contents of the net in the early phase of fishing, about 40-50 meters away from the vessel, avoiding crowded nets, fish stress, and physical damage. Using an air cannon, a sampling tube containing a mini-trawl is launched into the net to collect a representation of the fish. A hydraulic winch is then used to haul the net in for inspection. If the sampled fish are deemed unwanted catch, the seine is opened up to release them. Conducting this sampling process at such an early stage secures greater survival of fish should they need to be released. The grand prize winning team includes: Bjoernar Isakesen, Kurt Hansen, and Jostein Saltskaar.

SERIOUS HARE - Fishing nets maim and kill thousands of marine mammals and reptiles every year. This leatherback turtle is lucky to have been spotted.

LINKS & REFERENCE

http://assets.panda.org/downloads/bycatch_paper.pdf

http://wwf.panda.org/about_our_earth/blue_planet/problems/problems_fishing/destructive_fishing/

http://slowfood.com/slowfish/pagine/eng/pagina.lasso?-id_pg=43

https://www.reuters.com/article/us-environment-fish-idUSKBN19H1A8

https://www.worldwildlife.org/initiatives/international-smart-gear-competition

https://www.worldwildlife.org/threats/bycatch

MARINE LIFE - This humpback whale is one example of a magnificent animal that is at the mercy of human activity. Humans are for the most part unaware of the harm their fast-lane lifestyles are causing. We aim to change that by doing all we can to promote ocean literacy.

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