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A specific study of Orange Roughy, a highly fished species in deep waters in and around Eastern Australia and Western New Zealand (see maps below) is a salient study to illustrate the effects of climate on specific fisheries. Orange roughy typically live in geographic features in the ocean, such as seamounts and canyons, as shown by these two illustrations. They consume other fish, squids and crustaceans (Biology of Orange Roughy, 2002), which in turn consume Planktonplankton. The ocean climate around this area of the ocean is dominated by the East Australian Current (Cai et al., 2005). This current is expected to increase with projected climate change; on first glance, this appears beneficial for plankton, and by extension, Orange Roughy via intermediate trophic levels. However, this portion of the ocean is also expected to increase by roughly 2 degrees C (Haysa, Richardsonb, & Robinson, 2005). As a result, plankton may be displaced from their correct temperature, and since they can't migrate to other areas, they may be depleted. Monitoring needs to be implemented to discover how plankton levels are being affected. Also, the increased circulation should increase flow of nutrients to the deep ocean in Orange Roughy's habitat. Therefore, much monitoring needs to be implemented to discover how these factors will interact to affect Roughy population.
Western North American Coastal Zone
From 2003-2005, along the Northern California Current, on the West Coast of North America, went through a warming period similar to those related to ENSO, El Nino - Southern Oscillation events, however, southern waters were in an ENSO neutral state, accompanied by delayed upwelling and a lower plankton biomass (Peterson, 2006). Paleoclimatic data suggest that upwelling in the California current system is positively correlated with temperature over millennial timescales. Furthermore, upwelling along the California coast has increased over the past 30 years, and these increases are expected to continue. There is also the possibility, however, of the waters becoming increasingly stratified, which would likely result in a decrease in upwelling. It is also fairly certain that advection should increase in the California current (Harley, 2006). The upwelling could have a beneficial effect on the ecosystem if it is not too strong, but advection would likely have an adverse effect. One study links some of these changes to a decrease in the population growth rates of the northern California Chinook Salmon. The Salmon salmon numbers were negatively effected by increases in sea surface temperature, curl, scalar-wind and pseudo-wind stress, while positively effected by increased seasonal upwelling (Wells, 2007).
Based on this data, we predict that it is likely that the populations of fish in this region will be negatively affected by climate change. This would have to be taken into account and stricter enforcements would be needed to produce the same results that would be expected without climate change (Harley, 2006). This would most likely be done through changing the quotas placed on important species in by changing the number of fish that are allowed to be removed from the region. Technological restrictions and marine protected areas could also play a role. However, if the benefits of the upwelling are seen to be outweighing the harm done, these restrictions could probably be relaxed. Changing restrictions in this area should be relatively easy as there are already species-specific laws enforced in these waters by the Pacific Fishery Management Council (PFMC URL).
Western South America Coastal Zone
Coastal Fishery fisheries off of South America resides at reside in an upwelling zone. This upwelling goes through cycles during ENSO cycles. Mortality rates were highest during EN El-Nino events (Hernandez-Miranda, 2006). There is a chance that there could be a long toward shift in the climate towards the ENEl-Nino, which would most likely have a negative effect on fish populations (Collins, 2005). Another evaluation predicts global warming will ultimately lead to longer and weaker ENSO cycles. This occurs via complex interactions between currents and atmospheric circulation. If the first case occurs and the system shifts in the El Nino spectrum, then the fish populations in this region stand to be much lower than would be expected otherwise (Zhang, 2005). In the 1990's this region underwent several mild to moderate EN El-Nino events, without intervening LN La-Nina events (IPCC, 2001), perhaps indicative of the first case (shift toward El-Nino).
Temperature anomolies during an el nino El-Nino event (Image courtesy of CPC ENSO Main Page)
If this trend is the case then it would have to be taken into account and stricter enforcements would be needed to produce the same results that would be expected without climate change. The fisheries in these regions might also take additional hits during elEl-nino Nino years, so additional protection might be required for these years. If the second case happens (longer and weaker ENSO cycles), then climate change will most likely play a much smaller role in the management of this fishery, and plans can be carried out without too much modification for climate change. There is an ongoing debate in Peru regarding the creation of a Marine Protected Area (Working Paper, 2004), which could possibly be used to safeguard fish populations to a greater extent than they would in other regions. ENSO is also linked to changes in weather, which have effects on the terrestrial environment of Western South America. Floods and landslides in Peru during El-Nino years cause an increased mortality rate by 40% (IPCC, 2001).
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These ecosystems also contribute to the livelihoods of coastal communities in Kenya, Mozambique, Tanzania, Madagascar, Mauritius, and Seychelles. The sustainable management of these sectors is crucial to the development of most nations, however, the complexities of marine systems and their associated scientific, economic, social, legal, and institutional issues make it difficult to implement effective management. Despite this, management systems that incorporate stakeholders in planning and implementation of marine protected areas (MPAs) and integrated coastal area management (ICAM) have been established in many WIO Western Indian Ocean countries (Wildlife Conservation Society).
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A proper enforcement of the protection of reserves would achieve conservation of both representativeness (middle) and high diversity areas (edge). If necessary, there should be a collection of reserves that have the specific purpose of improving local yields of exploited species. The sizes of biodiversity reserves should be determined by local habitat heterogeneity and should be designed to maximize their benefit to adjacent areas while minimizing their size.
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Climate change could cause an increase in severe weather, which could lead to an increased amount of precipitation. Costal Coastal fisheries could be effected affected by the increased amount of fresh water coming from the rivers. The "flushing rates" (where the fresh water and saltwater mix) could be effectedaffected. The estuaries are important nursing areas for fish and shellfish. Sea level change could have an effect on coastal erosion, resulting in the loss of costal coastal marsh habitats. Climate change may not have that great of an effect on offshore fish, such as tuna and mackerel, or bottom-oriented fish, such as snappers because they of their mobility. With the increase in temperature of the Gulf of Mexico there is a possibility to shift the "zone of inhabitance" of tropical species northward, which might cause a loss in resources for lower latitude fishing nations. (NOAA fisheries service, n.d) Some examples of fish that are being fished in the Gulf of Mexico are red snapper, mackerel, swordfish, grouper and tilefish. (Fisheries and aquaculture, n.d.) A specific country, Cuba, fishes high-valued finfish and shellfish. (Adams, n.d.)
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The Southern Ocean (Antarctic Ocean) is important to managing climate change with respect to the worldwide ocean because the Antarctic Circumpolar Current (ACC) allows for mixing between the three great oceans. The ACC also serves to buffer Antarctica from the variable climate of higher latitudes (Gille 2002). Furthermore, Antarctic fish have a low tolerance for increases in temperature. This intolerance is due to the fact that in low temperature water, oxygen is more soluble in colder water than in warmer water, so Antarctica fish have a lower capacity for transporting oxygen in their blood, such as via mechanisms including their having fewer red blood cells. that The number of red blood cells possessed by these fish would not be sufficient at higher temperatures (Mark 2002). Since From the 1950's though the 1990's the water in the Southern Ocean has increased 0.17ºC±.06ºC. This , a greater change than the overall ocean (Gille 2002).
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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 freshening increase of freshwater in the oceans could have a damaging effect on the Ocean Conveyor (a current which transports warm water from the tropics to Northern latitudes). There are different scenarios for the slowing down of the 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 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 the caseas severe as predicted, or that it change will happen on longer time scales, such restrictions would be able to could be scaled back.
Changes in Salinity in the North Atlantic (B. Dickson, et. al., in Nature, April 2002)
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