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There is evidence of lower salinity in the North Atlantic coming from melting of polar ice caps and diluting the ocean with more fresh water. An increased amount of fresh water could come from glaciers or sea ice melting, an increased amount of precipitation, or from rivers. The increase of freshwater in the oceans could have a damaging effect on the Ocean Conveyor (a current currents which transports transport warm water from the tropics to Northern latitudes on the surface; the water cools as it travels north, and then sinks and travels south again). There are different scenarios for the slowing down of the ocean conveyor Ocean Conveyor between the next two decade or in a hundred years (Gagosian, 2007). There is paleoclimatic evidence for rapid climatic changes as a result of the shut down of the ocean conveyorOcean Conveyor. If this were to happen, the Gulf Stream could possibly be deflected downwards, which would prevent the transfer of warm water from the tropics to the high Northern latitudes. In this scenario the high latitude would go through a very rapid cooling periods that could have devastating effects on the ecosystem (Gagosian, 2007). For this reason we assert that this region should be carefully monitored in order to recognize this trend early. There should also be a significant effort put into maintaining the robustness of the ecosystem in this area. To do this, restrictions placed on the fishery in this region should be higher than they would otherwise be set. If research proves this scenario is not as severe as predicted, or that change will happen on longer time scales, such restrictions could be scaled back.
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Scientists are using tropical foreign fish to gauge how fish around Australia and Tasmania will react to higher see sea temperatures. Also, they are trying to learn what smaller fish to feed the native fish in order to produce maximum size and yield. Researches have found that barramundi grow more quickly when fed lupins rather than smaller fish like anchovies. (Barra, 2007).
Another team of scientists studied how the depth of water and climate change related to fish populations. The science team examined 555 specimens ranging in age from two to 128 years, with birth years from 1861 to 1993. Growth rates of a coastal species, juvenile morwong, in the 1990s were 28.5 per cent faster than at the beginning of the period under assessment in the mid-1950s. By comparison, juvenile oreos, a species found at depths of around 1,000 meters, were growing 27.9 per cent slower than in the 1860s. There was no or little change in the growth rates of species found between 500 and 1,000 meters. correlations Correlations for long-lived shallow and deep-water species suggest that water temperatures have been a primary factor in determining juvenile growth rates in the species examined - Banded morwong, redfish, Jackass Morwong, Spiky, black, smooth and Warty Oreo and Orange roughy. In the southwest Pacific east of Tasmania sea surface temperatures have risen nearly two degrees, based on the results of a monitoring program at Maria Island. Coinciding with this has been a southward shift in South Pacific zonal winds, which has strengthened the warm, pole ward-flowing East Australian Current. (CSIRO, 2007).
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Rising temperature of climate change is already noticeable in the deep layers of the Japan Sea and the shrinking ice of the Sea of Okhotsk, while rising sea levels have been occurring along Sanriku coasts and the Pacific Ocean side for the past 100 years. Southern plankton which have never been seen as north northerly as Japan now threatens oysters, shellfish, and sardinesardines, all of which are important to Japan's fishing industry. (Ichikawa, 104-105) The great change afflicted by even a few degrees rise in temperature is evident in the case of bluefin tuna. Able to spawn up to six degrees below its optimal temperature of 26 degrees Celsius, bluefin tuna, however, cannot spawn three degrees above that number. Based on the study and projection of Shingo Kimura, professor of marine environmental science at the University of Tokyo, tuna population, already hurt by overfishing, will be so exacerbated that populations will shrink to 37% its current levels by 2099. As Japan is the biggest supplies of bluefin tuna and given the internationality of the fishing industry, a decline in numbers hurt will also hurt China, South Korean, China, and the US. (Bluefin, 1) In a culture that is based on fishing, Japan faces not just the threat of environmental change but also of cultural change.
The increased carbon dioxide from combustion has in turn increased acidity of the ocean by 30%, drastically altering the chemistry of the ocean. In the North Pacific waters, which is the most in general more acidic than other waters because it is colder, older, and absorbs more carbon, coral reef reefs are being tested at saturation points, when growth cannot overcome disintegration due to acidity. (Brenton, 1) In the Indo-Pacific waters, which hold 75% the world's coral reefs, researchers of University of North Carolina at Chapel Hill found in surveys found study decline, threatening a decline of coral reefs which threatens tourism, that coastal regions that once found safety behind the buffering reefs, and fisheries. (University of North Carolina at Chapel Hill, 1)
As Royce Pollard of Vancouver, Washington said, "The fish gave us our first indication." (Joling, 1) The effect of climate change on fisheries in many cases is a warning sign of more adverse effects to follow. In the case of Alaska salmon run failures of 1997-1998, Chinook salmon catch were only 43,500, half than that of the catch the year before. Though for For the next year, the Alaska Department of Fish and Game forecasted a catch of 24.8 million, and only 12.1 million were caught. Also in 1997-1998, Alaska experienced a 2.0 degrees Celsius increase in surface temperature and a 1.5-2.0 degrees Celsius increase in deep ocean temperature. (Kruse , 61) Pacific white-dolphins, albacore, walleye Pollock, all southern species, were sighted in northern Gulf of Alaska. A sub-polar phytoplankton known as Coccolithophore blooms appeared suddenly, indicating high light intensity and low nutrients in the water. All these changes, which were already predicted in 1995 by ocean scientists who studied global warming on the Bering Sea, confirmed the need to understand more climate change in Alaska. (Kruse, 60) As a result, the North Pacific Fishery Management Council and the Marine Conservation Alliance have closed US waters in the Arctic Ocean to fishing until enough research is present to understand climate change and until a management regime is put in place for climate change. (Marine Conservation Alliance, 1)
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