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Examples are swordfish, seals and gannets. Apex predators, such as orcas, which can consume seals, and shortfin mako sharks, which can consume swordfish, make up a fifth trophic level. Baleen whales can consume zooplankton and krill directly, leading to a food chain with only three or four trophic levels.
The swordfish (Xiphias gladius), also known as the broadbill [5] in some countries, are large, highly migratory predatory fish characterized by a long, flat, pointed bill. They are a popular sport fish of the billfish category. Swordfish are elongated, round-bodied, and lose all teeth and scales by adulthood.
Predators have devised various countermeasures to undermine the defensive shoaling and schooling manoeuvres of forage fish. The sailfish raises its sail to make it appear much larger so it can herd a school of fish or squid. Swordfish charge at high speed through forage fish schools, slashing with their swords to kill or stun prey. They then ...
Large predator fish with higher trophic levels have been depleted in wild fisheries. As a result, the fishing industry has been systematically "fishing down the food web", targeting fish species at progressively decreasing trophic levels. The trophic level of a fish is the position it occupies on the food chain.
Loss of habitat could largely remove some of the most important predators — and some of the most commercially important seafood species — from the Climate change takes habitat from big fish ...
For example, the Atlantic catch of blue marlin declined in the 1960s. This was accompanied by an increase in sailfish catch. The sailfish catch then declined from the end of the 1970s to the end of the 1980s, compensated by an increase in swordfish catch. As a result, overall billfish catches remained fairly stable. [66]
The sighting was made off the coast of western Australia, the charter boat company said.
The main reason for this behavior is thought to be to escape from underwater predators, [3] [4] [5] which include swordfish, mackerel, tuna, and marlin, among others, [6] though their periods of flight expose them to attack by avian predators such as frigate birds.