The present results suggest that mosquito immatures are not the preferred food of mosquitofish when fish larvae are present in their natural habitats. Since mosquitofish and carp larvae have overlapping natural habitats and prey preferences are the invasive mosquitofish may have a substantial impact on native communities of invertebrates and fish. This way, they are equally important for extensive fisheries and conservation management.
fish and fisheries of india by v g jhingran pdf 151
Download Zip: https://7curioqconsme.blogspot.com/?jj=2vGq2Y
Harvest stagnation in wild fisheries and overexploitation of popular marine species, combined with a growing demand for high-quality protein, encouraged aquaculturists to domesticate other marine species.[9][10] At the outset of modern aquaculture, many were optimistic that a "Blue Revolution" could take place in aquaculture, just as the Green Revolution of the 20th century had revolutionized agriculture.[11] Although land animals had long been domesticated, most seafood species were still caught from the wild. Concerned about the impact of growing demand for seafood on the world's oceans, prominent ocean explorer Jacques Cousteau wrote in 1973: "With earth's burgeoning human populations to feed, we must turn to the sea with new understanding and new technology."[12]
Seaweed farming or kelp farming is the practice of cultivating and harvesting seaweed. In its simplest form, it consists of the management of naturally found batches. In its most advanced form, it consists of fully controlling the life cycle of the algae. The top seven most cultivated seaweed taxa are Eucheuma spp., Kappaphycus alvarezii, Gracilaria spp., Saccharina japonica, Undaria pinnatifida, Pyropia spp., and Sargassum fusiforme. Eucheuma and K. alvarezii are farmed for carrageenan (a gelling agent); Gracilaria is farmed for agar; while the rest are farmed for food.[27] The largest seaweed-producing countries are China, Indonesia, and the Philippines. Other notable producers include South Korea, North Korea, Japan, Malaysia, and Zanzibar (Tanzania).[28] Seaweed farming has frequently been developed as an alternative to improve economic conditions and to reduce fishing pressure and overexploited fisheries.[29]
In 2012, the total world production of fisheries was 158 million tonnes, of which aquaculture contributed 66.6 million tonnes, about 42%.[54] The growth rate of worldwide aquaculture has been sustained and rapid, averaging about 8% per year for over 30 years, while the take from wild fisheries has been essentially flat for the last decade. The aquaculture market reached $86 billion[55] in 2009.[56]
A United Nations report titled The State of the World Fisheries and Aquaculture released in May 2014 maintained fisheries and aquaculture support the livelihoods of some 60 million people in Asia and Africa.[61] FAO estimates that in 2016, overall, women accounted for nearly 14 percent of all people directly engaged in the fisheries and aquaculture primary sector.[21]
In 2001, scientists Reg Watson and Daniel Pauly expressed concerns that China was over reporting its catch from wild fisheries in the 1990s.[6][63] They said that made it appear that the global catch since 1988 was increasing annually by 300,000 tonnes, whereas it was really shrinking annually by 350,000 tonnes. Watson and Pauly suggested this may be have been related to Chinese policies where state entities that monitored the economy were also tasked with increasing output. Also, until more recently, the promotion of Chinese officials was based on production increases from their own areas.[64][65]
Sometimes the term "integrated aquaculture" is used to describe the integration of monocultures through water transfer.[73] For all intents and purposes, however, the terms "IMTA" and "integrated aquaculture" differ only in their degree of descriptiveness. Aquaponics, fractionated aquaculture, integrated agriculture-aquaculture systems, integrated peri-urban-aquaculture systems, and integrated fisheries-aquaculture systems are other variations of the IMTA concept.
If performed without consideration for potential local environmental impacts, aquaculture in inland waters can result in more environmental damage than wild fisheries, though with less waste produced per kg on a global scale.[83] Local concerns with aquaculture in inland waters may include waste handling, side-effects of antibiotics, competition between farmed and wild animals, and the potential introduction of invasive plant and animal species, or foreign pathogens, particularly if unprocessed fish are used to feed more marketable carnivorous fish. If non-local live feeds are used, aquaculture may introduce exotic plants or animals with disastrous effects. Improvements in methods resulting from advances in research and the availability of commercial feeds has reduced some of these concerns since their greater prevalence in the 1990s and 2000s .[84][85]
As the salmon farming industry expands, it requires more wild forage fish for feed, at a time when seventy-five percent of the world's monitored fisheries are already near to or have exceeded their maximum sustainable yield.[7] The industrial-scale extraction of wild forage fish for salmon farming then impacts the survivability of the wild predator fish who rely on them for food. An important step in reducing the impact of aquaculture on wild fish is shifting carnivorous species to plant-based feeds. Salmon feeds, for example, have gone from containing only fishmeal and oil to containing 40 percent plant protein.[93] The USDA has also experimented with using grain-based feeds for farmed trout.[94] When properly formulated (and often mixed with fishmeal or oil), plant-based feeds can provide proper nutrition and similar growth rates in carnivorous farmed fish.[95]
Global wild fisheries are in decline, with valuable habitat such as estuaries in critical condition.[141] The aquaculture or farming of piscivorous fish, like salmon, does not help the problem because they need to eat products from other fish, such as fish meal and fish oil. Studies have shown that salmon farming has major negative impacts on wild salmon, as well as the forage fish that need to be caught to feed them.[142][143] Fish that are higher on the food chain are less efficient sources of food energy.
The UN Sustainable Development Goal 14 ("life below water"), Target 14.7 includes aquaculture: "By 2030, increase the economic benefits to small island developing states and least developed countries from the sustainable use of marine resources, including through sustainable management of fisheries, aquaculture and tourism".[150][151] Aquaculture's contribution to GDP is not included in SDG Target 14.7 but methods for quantifying this have been explored by FAO.[22] 2ff7e9595c
Comments