Most fisheries throughout the world are over–exploited and are pushed past their biological limit. With an expected rise in greenhouse gas emissions, fisheries yield could suffer a dramatic decrease. Countries that strongly rely on food and revenue outcomes of fisheries will be negatively impacted both in terms of food supply and socioeconomic factors. Theoretical and experimental studies have shown that physiology, life history, productivity, and distribution of marine organisms are dependent on conditions of the ocean such as temperature, currents, and coastal upwelling which are all factors affected by climate change. Through various climate change scenarios, Cheung et al. 2010 aims to project future changes in the maximum catch potential of marine fish and invertebrates in global oceans from 2005 to 2055. It is expected that climate change will have an effect on the ocean, which will result in an effect on goods and services provided by marine ecosystems. Alteration of current ocean conditions can have an effect on primary productivity, species distribution, community, and food web structure. It has been observed that marine fish and invertebrates shift distribution according to climate change. They generally move towards a higher latitude and deeper water where temperatures are less extreme. While production could increase in higher latitudinal areas, those with lower latitudes will suffer. This will have a direct effect on human society around the world. – Lauren Lambert
Cheung, William W. L., Lam, Vicky W. Y., Sarmiento, Jorge L., Kearney, Kelly, Watson, Reg, Zeller, Dirk and Pauly, Daniel. (2010), Large-scale redistribution of maximum fisheries catch potential in the global ocean under climate change. Global Change Biology, 16: 24–35.
Cheung et al. 2010 used several models to make their predictions about maximum catch potential by the year 2055. The empirical model can be applied to evaluate how fisheries productivity could be affected by climate change based on primary production and distribution range of 1066 species of exploited fish and invertebrates. Future distributions of these species are represented using dynamic bioclimate envelope models. These models identified species preferences with environmental conditions such as water temperature, salinity, distance from sea ice, and habitat types. A large range of taxonomic groups was used, including krill, shrimp, anchovy, cod, tuna, and sharks. The distribution of each species was determined from an algorithm that estimated the relative abundance of species. Habitat type was also taken into consideration. These included coral reef, seamounts, estuaries, inshore, offshore, continental shelf, continental slope, and abyssal habitats. The models assume that species distributions are dependent on latitude, bathymetric, and habitat gradients. Two climate change scenarios were included in the study with both high and low greenhouse gas emissions. To predict primary production from the world ocean, published empirical models and algorithms were used. Primary production was predicted by looking at surface chlorophyll content and distribution, light supply, vertical attenuation, and temperature of surface. The annual maximum catch potential was calculated based on total primary production for the two climate change scenarios.
Cheung et al. 2010 found that climate change may have a significant effect on distribution of catch potential between tropical and high latitude regions.
Results from the higher greenhouse gas emission scenarios show that impacts in Indo-Pacific regions are the most intense, with up to 50% decrease in catch potential by 2055. Semi–enclosed areas and many coastal regions also show a decline. Catch potential showed a more than 50% increase in higher latitudinal regions. In contrast to the results of this model, the pattern of changes under the low greenhouse gas emission scenario is less clear. Changes in catch potential by 2055 for all regions under the high range scenario were 1.6 times higher than the changes under low range scenario. This suggests that climate change may have a large impact on distribution of maximum catch potential, which is extremely important in predicting the potential impact that climate change could have on fisheries productivity.
Species distribution will undergo a shift in range as the ocean temperature increases, resulting in a decrease in catch potential in these areas. High latitude regions will open up new habitat for lower latitude species, causing catch potential to increase. These projected changes could have implications for global security. Climate change may have a negative impact on food security in tropical communities that are dependent on fisheries production as a food source and revenue. With rising agricultural problems as a result of climate change, this additional stress will have an extremely negative effect on the food security dilemma. The distribution change from coastal regions to offshore could also have an effect on the cost of fishing because boats will be forced to travel further away from land and be at sea for a longer period of time. The conclusion is that greenhouse gas emission could result in a worldwide redistribution of maximum catch potential.