Similar to a gillnet, the tangle net, or tooth net, is a type of nylon fishing net. Left in the water for no more than two days, and allowing bycatch to be released alive, this net is considered to be less harmful that other nets. The tangle net is used in the Philippines by commercial fishermen, as well as by the scientific community. When spent, these nets can be bundled, and left on the sea floor to collect smaller species. These bundles are known locally as lumen lumen nets.
The tangle net originated in British Columbia, Canada, as a gear specifically developed for selective fisheries. [1] Tangle nets have smaller mesh sizes than standard gillnets. They are designed to catch fish by their nose or jaw, enabling bycatch to be resuscitated and released unharmed. [2] [3] These nets are made with a very thin light nylon rope, have a small mesh and are strung between two ropes, a top rope with floats, and a bottom rope with weights. Dropped to the bottom of the ocean, located and retrieved through the use of a guide line and buoy, these nets have allowed both fishermen and scientists to reach areas not previously accessible. Tangle nets are generally left on the bottom for no more than a day or two so that the fish and bycatch does not die and spoil.[ citation needed ]
For the last two decades tangle nets have been set in deep water near steep underwater cliffs off many islands in the Philippines by local fishermen in order to supplement their income through catching commercially valuable mollusks. Scientists have used this technique in recent years to explore the deep water marine habitat. The rich species diversity of the Philippine Islands has been explored through the use of tangle nets which are able to obtain specimens from areas not reachable by traditional methods of using trawls and dredges. [4] Through the placement of tangle nets 50 to 100 meters long, at depths from 100 meters to 400 meters, this cryptic marine habitat has been explored and many new and/or rare species of gastropods and crustaceans have been acquired. [5] The success of deep set tangle nets was further exploited when Philippe Bouchet and Danilo Largo launched an expedition in 2004 to explore the Panglao area, known as the 2004 Panglao Marine Biodiversity Project. [6] [7]
When tangle nets are damaged beyond repair they are twisted and wrapped into long bundles, which the Philippine locals call lumen lumen nets. These long, sausage-like bundles are placed on the sea bottom along drop-offs in deep water with strong currents and left for several months at a time, which allows time for veligers to settle and larvae to grow. Lumen lumen nets have yielded many more species of marine animals, including many very small species of micromollusks. [8]
Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch different species of fishes or sometimes targeted species. Trawls are often called towed gear or dragged gear.
Bycatch, in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juveniles of the target species. The term "bycatch" is also sometimes used for untargeted catch in other forms of animal harvesting or collecting. Non-marine species that are caught but regarded as generally "undesirable" are referred to as "rough fish" and "coarse fish".
The Irrawaddy dolphin is a euryhaline species of oceanic dolphin found in scattered subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal and Southeast Asia. It closely resembles the Australian snubfin dolphin and was not described as a separate species until 2005. It has a slate blue to a slate gray color. Although found in much of the riverine and marine zones of South and Southeast Asia, the only concentrated lagoon populations are found in Chilika Lake in Odisha, India and Songkhla Lake in southern Thailand.
The vaquita is a species of porpoise endemic to the northern end of the Gulf of California in Baja California, Mexico. Averaging 150 cm (4.9 ft) (females) or 140 cm (4.6 ft) (males) in length, it is the smallest of all living cetaceans. The species is currently on the brink of extinction, and currently listed as Critically Endangered by the IUCN Red List; the steep decline in abundance is primarily due to bycatch in gillnets from the illegal totoaba fishery.
A shark net is a submerged net placed at beaches designed to intercept large marine animals including sharks, with the aim to reduce the likelihood of shark attacks on swimmers. The majority of shark nets used are gillnets which is a wall of netting that hangs in the water and captures the marine animals by entanglement, however only around 10% of catch is the intended target shark species. The nets in Queensland, Australia, are typically 186m long, set at a depth of 6m, have a mesh size of 500mm and are designed to catch sharks longer than 2m in length. The nets in New South Wales, Australia, are typically 150m long, set on the sea floor, extending approximately 6m up the water column, are designed to catch sharks longer than 2m in length. Shark nets do not create an exclusion zone between sharks and humans, and are not to be confused with shark barriers.
Gillnetting is a fishing method that uses gillnets: vertical panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water. The floats are sometimes called "corks" and the line with corks is generally referred to as a "cork line." The line along the bottom of the panels is generally weighted. Traditionally this line has been weighted with lead and may be referred to as "lead line." A gillnet is normally set in a straight line. Gillnets can be characterized by mesh size, as well as colour and type of filament from which they are made. Fish may be caught by gillnets in three ways:
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the earth, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions. Large-scale commercial fishing is also known as industrial fishing.
A fishing net is a net used for 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.
Seine fishing is a method of fishing that employs a surrounding net, called a seine, that hangs vertically in the water with its bottom edge held down by weights and its top edge buoyed by floats. Seine nets can be deployed from the shore as a beach seine, or from a boat.
Cetacean bycatch is the incidental capture of non-target cetacean species such as dolphins, porpoises, and whales by fisheries. Bycatch can be caused by entanglement in fishing nets and lines, or direct capture by hooks or in trawl nets.
A turtle excluder device (TED) is a specialized device that allows a captured sea turtle to escape when caught in a fisherman's net.
Ghost nets are fishing nets that have been abandoned, lost or otherwise discarded in the ocean. 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. It's estimated that around 48,000 tons of ghost nets are generated each year, and these may linger in the oceans for a considerable time before breaking-up.
Drift netting is a fishing technique where nets, called drift nets, hang vertically in the water column without being anchored to the bottom. The nets are kept vertical in the water by floats attached to a rope along the top of the net and weights attached to another rope along the bottom of the net. Drift nets generally rely on the entanglement properties of loosely affixed netting. Folds of loose netting, much like a window drapery, snag on a fish's tail and fins and wrap the fish up in loose netting as it struggles to escape. However the nets can also function as gill nets if fish are captured when their gills get stuck in the net. The size of the mesh varies depending on the fish being targeted. These nets usually target schools of pelagic fish.
Unsustainable fishing methods refers to the utilization of the various fishing methods in order to capture or harvest fish at a rate which sees the declining of fish populations over time. These methods are observed to facilitate the destructive fishing practices that destroy ecosystems within the ocean, and is used as a tool for over-fishing which results in the depletion of fish populations at a rate that cannot be sustained.
Fishing techniques are methods for catching fish. The term may also be applied to methods for catching other aquatic animals such as molluscs and edible marine invertebrates.
This is a glossary of terms used in fisheries, fisheries management and fisheries science.
Tristichotrochus aculeatus, common name the prickly Japanese top shell, is a species of medium-sized deepwater sea snail, a marine gastropod mollusk in the subfamily Calliostomatinae of the family Calliostomatidae.
Notocochlis gualteriana, common name the comma necklace shell, is a species of predatory sea snail, a marine gastropod mollusk in the family Naticidae, the moon snails.
Lift nets, also called lever nets, are a method of fishing using nets that are submerged to a certain depth and then lifted out of the water vertically. The nets can be flat or shaped like a bag, a rectangle, a pyramid, or a cone. Lift nets can be hand-operated, boat-operated, or shore-operated. They typically use bait or a light-source as a fish-attractor. Lift nets are also sometimes called "dip nets", though that term applies more accurately to hand nets.
Fishing gear and methods used in Uganda are both modern and traditional. Fish in Uganda are caught mostly with plank canoes and to a lesser extent, fiberglass boats. Some dugout canoes are also still being used. The plank canoes are generally 4–12 m (13.12–39.37 ft) in length and dugout canoes average 3.5 m (11.48 ft). The total number of vessels is about 17,000 and about 20% of these are motorized. Artisanal fishermen use various gear including gillnets, seines and hook and line. In a number of localities, traditional methods including baskets, traps and mosquito nets continue to be used. The gear commonly used includes gillnets, lift nets, scoop-nets used in light fishing; hook and line gear and fish traps.
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