Advances in Discovering Solutions to Sustainable Fishing and Aquaculture through Satellite Remote Sensing

The global capture fisheries production has remained relatively stable over the past decade, while aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> production continues to rise. Capture fisheries face issues such as overfishing<!–[if supportFields]> XE “overfishing” <![endif]–><!–[if supportFields]><![endif]–>, depletion of key species habitats, and unstable global fuel prices. Aquaculture faces challenges such as competition for space, feed, labor, and disease outbreaks. Both methods face the impacts of climate change in the future. A solution to this problem is to apply satellite remotely sensed (SRS) information to fisheries. Saitoh et al. (2011) provide an overview of selected SRS systems along with two case studies investigating capture fisheries and aquaculture. The first case study discusses the application of SRS environmental data and vessel monitoring in a skipjack tuna fishery in the western North Pacific. The second focuses on the impact of climate change on scallop aquaculture in Funka Bay, Hokkaido Japan. These studies aim to provide perspective on the future of fisheries information systems. —Lauren Lambert
Saitoh S-I., Mugo R., Radiarta I N., Asaga S., Takahashi F., Hirawake T., Ishikawa Y., Awaji T., In T., and Shima S. 2011. Some operational uses of satellite remote sensing and marine GIS for sustainable fisheries and aquaculture. ICES Journal of Marine Science, 68: 687–695.

Saitoh et al. briefly describe operational fisheries oceanography in pelagic fisheries to gain a better perspective on how these information systems work. Operational oceanography provides high quality observational and modeled data for practical application. Inter aliaprovides services that allow for minimal search time by directing fishing fleets and vessels to areas with optimum catch availability. SRS systems measure sea surface temperature (SST)<!–[if supportFields]> XE “sea surface temperature (SST)” <![endif]–><!–[if supportFields]><![endif]–>, ocean color, sea surface height anomaly (SSHA), currents, and winds. These are the most important sets of data that shape operational oceanography. One application of SRS includes the ability to identify potential fishing zones (PFZ). SRS allows for a clear demonstration of relationships between target species and environmental factors. It also contributes to minimizing bycatch of endangered species. For example, SRS was used to keep loggerhead turtles from being caught while fishing for swordfish<!–[if supportFields]>XE “swordfish”<![endif]–><!–[if supportFields]><![endif]–> and tuna in the North Pacific. A tool used to decrease the amount of southern Bluefin from being caught in the eastern quota was also developed. The ability to study behavior and habitat utilization is important in fisheries oceanography.
Commercial fishing applications are mostly aimed to minimize search time and save fuel. TOREDAS is a fishery information system service that facilitates near-real-time data transfer through satellite connection during fisheries operations, predict PFZ’s based on scientific findings, and provide high value-added fisheries oceanographic information for global oceans. Skipjack tuna were studied using high-resolution spatial VMS data obtained via TOREDAS from pole and line fishing vessels from 2007 to 2009. Data consisted of latitude and longitude positions logged by the vessel’s GPS<!–[if supportFields]> XE “global positioning system (GPS)” <![endif]–><!–[if supportFields]><![endif]–> system. Vessel speed was calculated using distance travelled between polling points relative to travel time (~1 minute). A histogram of estimated vessel speeds was used to categorize vessel activity. Only data that was transmitted during hours of skipjack tuna fishing were used. Scallop aquaculture<!–[if supportFields]>XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> used SRS to explore potential impacts of climate change on aquaculture. The model consisted of two steps. First the suitability of sites for scallop aquaculture was determined using integrated remote sensing as well as a model based on geographic information system (GIS). The second modeled the effect of SST<!–[if supportFields]> XE “sea surface temperature (SST)” <![endif]–><!–[if supportFields]><![endif]–> warming on the previous model using temperature increases of 1, 2, or 4°C. This will provide framework for evaluating the impacts on climate change on aquaculture.
Searching for tuna schools is the most time consuming part of fishing. This results in increased fuel and labor costs that takes away from net profits. Satellite based VMS data are used to provide high-resolution temporal and spatial information on fishing activity to minimize search time. VMS data are more accurate than fishing logbooks because data can be accumulated much faster and are more accurate and complete. These data provide improvements to operational fishery forecasting models and management measure such as designing protected marine areas or effort control measures. Daily vessel trajectories are conducted from June 19-23, 2008. During pole fishing the vessel does not move, so fishing activity is therefore characterized by points associated with slow speeds. The vessel travels slower during fishing, gear deployment and retrieval, so this allows for simple data separation. However there are other factors that are not taken into account for why the vessels are slowed or stopped. For example, identification of fishing activity can be initiated when a school of fish swims by but does not respond to the bait and therefore provides false information. The vessel stops and data are collected, but no fish are caught.
The Japanese scallop is the most successful marine shellfish in japan with greater than 40% of Japanese scallop production coming from aquaculture<!–[if supportFields]>XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> farming. Changes in water temperature will affect the timing and levels of productivity across all coastal and pelagic marine systems. It threatens optimum grow out temperatures through changes in weather and ocean temperatures. After application of IPCC<!–[if supportFields]> XE “Intergovernmental Panel on Climate Change (IPCC)”<![endif]–><!–[if supportFields]><![endif]–> scenarios in the models for scallop aquaculture production, the sites had changed dramatically relative to original models. A STT increase of 1°C resulted in relatively no change, but 2 and 4°C changes decreased the most suitable area for production by 52 and 100%. These results suggest that climate change will have an influence on the development of scallop aquaculture through changes in suitability of sites. One solution to this problem is to implement a shellfish breeding program to increase temperature tolerance of these species.
Future research includes use of oceanographic datasets from satellites. The increasing miniaturization of communication devices and low cost of transmitting information make these systems more practical for delivering future oceanographic information. Programs such as Google Earth could be vital in advancing this process. Products would provide useful information for fisheries and aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> such as fishing ground updates, site suitability for aquaculture facilities, and safety information. SRS data is important in providing information from satellites that is vital for research, monitoring, and management of marine fisheries and sustainability of aquaculture systems.

Global Fish Meal and Aquaculture Pro-duction in Response to Climate Change

Climate variability and change has the potential to alter the balance of marine systems. Global aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> systems rely on small pelagic fish populations, fisheries productivity, fishmeal supply, and fish oil production. Aquaculture is dependent on fishmeal as food to serve as a primary source of protein, lipids, minerals, and vitamins. Fishmeal is produced using small pelagic fish such as sardines, anchovies, and mackerels. These species are short lived and fast growing, so their production is highly susceptible to environmental changes. Fisheries production has stabilized over the last decade, however aquaculture has continued to increase, particularly through production of low-value freshwater fish. Prediction of changes in fisheries yield that result from climate change are important to estimate. Merino et al. (2010) used bioeconomic models at two temporal scales with the objective of investigating environmental and human induced changes to aquaculture systems. Short-term economic hypotheses were that (i) there is no relationship between aquaculture production and fishmeal consumption, given that technological advances will reduce the dependency on fishmeal production; and (ii) fishmeal demand is linearly related to aquaculture expansion. Long-term models were based on two socioeconomic scenarios until the year 2080. The World Markets scenario was estimated using prices based on recent average and highest price records while The Global Commons scenario predicted limited expansion of aquaculture and population growth. —Lauren Lambert
Merino G., Manuel B., Christian M., 2010. Climate variability and change scenarios for a marine commodity: Modelling small pelagic fish, fisheries and fishmeal in a globalized market. Journal of Marine Systems 81, 196–205.

Merino et al. expect that climate change will have a negative effect on marine resources through reduced levels of primary production. Global aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> production relies on both carnivorous and herbivorous species. The majority of carnivorous species include salmonoids from Chile and Norway, and shrimp from Thailand and China<!–[if supportFields]> XE “China” <![endif]–><!–[if supportFields]><![endif]–>. Herbivorous species, mainly from China, make up 55% of global aquaculture production. Carnivorous species are dependent on fishmeal, however the amount of fishmeal used for herbivorous species is rising because of the improved growth rates and profits. The models combine the uncertainties of future climate and market effects on global fishmeal production and consumption.      
The first model used short-term impacts over a 10-year simulation to find the annual variable production rate of individual small pelagic fish stocks aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–>. The second was long-term (2080) and estimated environmental impacts on the same stocks by using primary production predictions as proxies for carrying capacities of fish stocks. The short-term simulation investigated the consequences of short-term climate change on fish and fishmeal systems. Biological, economic, and activity/investment components were observed through this simulation. The biological component computed expected yields and was modulated by expected primary production. The economic component estimated net profits for regional production systems by combining their costs with revenue from the global market. This was driven by outputs from the biological component, activity component, fishmeal price function, transformation, and shipping costs. The parameters of the global market are price records from 15 international fish markets. Activity and investment components express exploitation patterns in terms of catchability and fishing activity of specific stocks. The results of this simulation were presented in the form of bioeconomic indicators such as global exploitation index, estimate of global small pelagic fish caught, and a measure of traded fishmeal to global markets as well as average prices.
The fish stocks show fluctuation according to random variability in fish production. In years that fish stocks decline, the costs of obtaining fish at the same yield show a slight increase, and the small pelagic and fishmeal supply remains relatively constant. As fishmeal markets expand, fish production fluctuates as a result of climate change. Through this simulation, Merino et al.found that in years with negative environmental conditions the price of fishmeal would need to be increased while production levels stay the same. At the end of the 10-year simulation, the fish stocks global indicator was 23% of optimal levels. Under these same conditions, the combination of random negative environmental impacts and increases in demand will continue to reduce the size of the fish stocks.
Long-term simulations investigated the impacts of changes in primary production under two different management scenarios. These are short and long term models that use actual data from 1997–2004 for 3 regional production systems. The import and export data from the International Fishmeal and Fish Oil Organization (IFFO) was used to estimate the size of these fish stocks, fleets, and transforming industries. The global market only works under the condition that fish stocks are currently exploited at their maximum sustainability capacity and that the differences in fishmeal production are reflective sof the difference in available fish stocks, fleets, and technology. This allows for investigation of impact of climate variability on production systems that trade products in the global commodity markets. The Global Commons management scenario showed that resulting fish biomass, exploitation levels, fish yield, and market trade are similar to present conditions. The World Market scenario shows a decline in all parameters that were tested. The model showed that production appears to be sustainable over the 10-year period, but fishmeal prices will rise. 
 The results of the long-term scenarios show changes in biomass of small pelagic fish, index of global exploitation level, total production of small pelagic fish, and quantity of fishmeal in the markets. Sustainability of small pelagic resources is more dependent on how society responds to climate change than to the magnitude of the alterations. There is a link between global climate change and aquaculture<!–[if supportFields]>XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> dynamics in relation to the demand for natural resources and limits of ecosystem services. Ecosystems are expected to respond to global warming through variations in primary production and species capacity parameters. 

Implications for Disease Control in Aquacul-ture

With over-exploitation of coastal fisheries and rising disease rates of ocean populations, fish abundance levels have been dramatically decreasing. The outbreak, persistence, and eradication of infectious diseases are often dependent on the density of the host population. The growth of aquaculture has produced a large density of fish in fish farms, making them more susceptible to disease. They are often open to the surrounding ecosystem and therefore are exposed to wild fish populations as well. Krkošek (2010) explores the connection between outbreaks of parasites in wild salmon and density threshold in aquaculture growth. High densities lead to higher transmission rates of infectious diseases because of increased contact with infected individuals. Wild-farmed populations can exceed host density threshold from an influx of migrating individuals, increases in aquaculture production, or environmental changes such as global warming. In contrast, populations with lower densities show a much lower rate of susceptibility and slower rate of disease spread. Fisheries reduce abundance levels of wild populations, which should lead to a decrease in disease and parasite abundance as well. However when a predatory population declines, the prey population increases and therefore increases susceptibility of disease. —Lauren Lambert
Krkošek, M., 2010. Host density thresholds and disease control for fisheries and aquaculture. Aquaculture Environmental Interactions 1: 21–32.

Industrial aquaculture and number of fish farms are growing. They often have larger domesticated abundance than wild populations. These domesticated populations are concentrated by pens, nets, cages, rafts, or ropes that are open to the surrounding areas. Therefore any disease or parasites that arise in these populations will be open to the surrounding ecosystem and can be transmitted to wild populations. This is a major challenge for the aquaculture industry because of the concern for conservation of the wild marine ecosystem. The most common measure of disease persistence is known as R0, or the net reproductive value. If R0 >1, the parasite population can invade host population. If R0 <1, infections do not replace themselves and parasite populations will eventually die out. This is the process of disease eradication. Populations are susceptible to microparasites such as viruses, bacteria, and protists. Dynamics of microparasite diseases can be modeled by dividing host populations into categories determining status of infection (susceptible, infected, recovered). Individuals become infected by being exposed to others that are infected. Even if an individual recovers, over time it becomes more susceptible to disease and could become infected again. The number of infected individuals generated by a single individual can be determined by multiplying the average duration of infection period by the rate at which hosts become infected.
Macroparasites include helminths and arthropods such as intestinal worms and ectoparasitic copepods. Unlike microparasites, these must leave the initial host in order to complete their life cycle. They also produce sexually in or on a host. For example, sea lice reproduce on the surface tissue of fish. Models describing macroparasites must track free-living stages as well as number of parasites per host, per population. Birth and death rates, rate of infection of hosts, and host/parasite mortality rates are also determined.
Theory predicts that host density thresholds are important for host-parasite dynamics. For example, increases in sea lice in salmon were associated with small incremental changes. This is consistent with the theory in which a small increase in host density that crosses threshold triggers a sudden outbreak of disease. Threshold capacity could have been decreased by environmental conditions such as temperature, leading to an acceleration of an epidemic. Vaccination has contributed to the eradication of diseases in fish farms despite the large increase in fish production. Most developments of vaccines can only treat bacterial and viral diseases, and not parasitic ones.
Spatial scale of thresholds is dependent on physical characteristics that influence dispersion and survival of free-living parasites and infectious agents. Pathogens existing in marine environments are long lived and widely dispersed compared to those on land because they are able to be transported over long distances in a more stable condition of temperature and moisture. This is especially true in the case of wild marine populations that have hosts that are highly mobile or migratory which leads to spread of infection at a much more rapid rate. Outbreaks have been shown to follow the direction of currents, predicted using hydrodynamic modeling. With these migratory fish spreading disease to other populations, epidemics in fish farms can be spread over very large scales. However the infection is likely to decline with increased distance from the source population.
Parasitic life cycles are influenced by a variation of environmental factors such as temperature, moisture, and salinity. Global climate change can have a profound influence on these parameters. Developmental rates of parasites are highly dependent on the consistency of temperature. Knowledge of disease outbreaks and its possible influences has important implications for coastal fish farm planning. Minimizing transmission of pathogens among farm fish to wild hosts could increase the size of wild populations. This can be done by placing farms further away from wild fish migration routes and in locations that have low ocean tides and currents, to minimize rates of disease spreading. Selective breeding of fish that are resistant to disease can also provide the future populations with a higher survival rate. Increased vaccinations of fish, increased circulation of facilities, and maintaining lower density levels in these fish farms provides advances in disease control.

Effects of Fish-Farms on Marine Biodiversity Along the Mediterra-nean Coast

The expansion and growth of offshore mariculture is a growing business. The environmental effects of this industry are of particular concern because of the impacts they have on marine habitats and biodiversity<!–[if supportFields]>XE “biodiversity”<![endif]–><!–[if supportFields]><![endif]–>. Mirto et al. (2010) investigated the effects that fish farms have on the metazoan meiofaunal communities existing in areas exposed to fish farms along the coast of the Mediterranean Sea. The potential effects of fish farm effluents on the abundance and community composition of meiofauna were analyzed by comparing two different habitats in four different regions with different background trophic<!–[if supportFields]> XE “trophic” <![endif]–><!–[if supportFields]><![endif]–> conditions. It was found that there are conflicts between aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> and the conservation of marine habitats and benthic primary producers. The organic enrichment of sediments falls beneath the sea cages used by fish farms. This sedimentation of particulate waste products from the fish farm has a direct effect on the local habitat. The continuous deposition of feces and food pellets from fish cages can alter the quantity as well as biochemical composition of sediment organic matter. The extent to which these areas are affected differs in different regions/habitats. Investigating meiofaunal assemblages in different regions of the Mediterranean Sea identifies the changes that are caused by aquaculture on benthic ecosystems and can provide insight to what is going on in these marine communities. —Lauren Lambert
 Mirto, S., Silvia B., Cristina G., Maja K., Antonio P., Mariaspina S., Marianne H., and Perry R.I., Ommer RE., Barange M., Werner F. 2010. The challenge of adapting marine social-ecological systems to the additional stress of climate change. Current Opinion in Environmental Sustainability 2,  356–363.

Mirto et al. (2010) hypothesized that fish farms influence the meiofaunal assemblages of existing habitats. This includes abundance, community structure, and diversity. Four regions along the Mediterranean Coastal zones were selected in order to provide a variety of different environmental conditions. Two different habitats were selected, meadows of seagrass vs. soft non-vegetated bottoms. Control sites were also chosen to match conditions and environmental features found at the bottom of fish farm cages. These sites were located at a distance of at least 1000m upstream from the fish farms to be certain that this habitat would not be affected. The sediment protein, carbohydrate, and lipid contentents were determined. The amount of meiofauna was determined by sieving through 1000 mm sieve for macrobenthos and macroalgae, and 32 mm sieve to retain smaller meiofauna. The differences between control and impact sediments were calculated using three-way-analysis-of-variance (ANOVA<!–[if supportFields]> XE “ANOVA”<![endif]–><!–[if supportFields]><![endif]–>). When significant differences were observed between the two groups, a post-hoc Student-Newman-Kuels test (SNK) was also used to assess this information.
The observations of the study showed differences between impacted and control sites as well as in the four geographical areas. SNK tests revealed a consistent increase in biopolymeric C concentrations in farm-impacted vegetated sediments in Cyprus, both habitats in Greece, and in non-vegetated sediments in Italy. Protein to carbohydrate ratio increased in both habitats in Italy and non-vegetated sediments in Spain. A decrease in impact sediments was observed in both habitats of Greece. The SNK test indicated a significant increase of meiofaunal abundance in impacted sites with vegetated sediments in Cyprus, in non-vegetated sediments in Italy, but no difference between control groups in other regions. In summary, Mirto et al. found that the differences between control and sites impacted by fish farms varied depending on the region.
Differences between impact and control sites in the meiofaunal community composition were only significant in non-vegetated sediments in Cyprus or Greece. Nematodes and Copepods were the most dominant taxa followed by polychaetes, ostracods, turbellarians, oligochaetes, gastrotrichs, and all other taxa. The richness of meiofaunal taxa decreased significantly in impacted sites in non-vegetated sediments but no significant differences between impact and control sites were observed in sea grass sediments. The taxa that disappeared beneath the cages varied throughout the sites, but always compromised the rare taxa which make up  <1% of total meiofaunal abundance.
Fish farms typically have an effect on the attributes of the benthic environment beneath cages and show a significant amount of modifications in the abundance, biomass, species composition, and evenness of meio and macrofauna.  However these observed changes associated with the presence of fish farm effluents are often not consistent because meiofaunal abundance may increase or decrease beneath the cage depending on characteristics of the site or farm. The abundance of meiofauna was generally higher in fish farm sediments, which could be a result of limited organic enrichment in the sediments beneath the cages. There is a clear and consistent meiofaunal response to the fish farm deposition in sea grass sediments. Posidonia oceanica<!–[if supportFields]> XE “Posidonia oceanica” <![endif]–><!–[if supportFields]><![endif]–> is the sea grass existing on the sites that plays a key ecological role for many of the organisms and assemblages by preserving biodiversity<!–[if supportFields]>XE “biodiversity”<![endif]–><!–[if supportFields]><![endif]–>. It is difficult to detect effects of fish farm biodeposition on sea grass meadows because the grass masks the changes in organic composition. The presence of a large number of filter feeders and detritus feeders within sea grass beds can also act as a buffer for the organic enrichment because of the amount of biodeposits that they consume.

Actual changes are difficult to know because of these supplemental factors. However in the long term, the increased sedimentation and waste particles that result from these farms does lead to the deterioration of the sea grass system and will eventually result in disruption of the ecosystem in place. Fish farm biodeposition in the Mediterranean Sea can provoke changes in meiofaunal abundance, community structure, and biodiversity<!–[if supportFields]> XE “biodiversity” <![endif]–><!–[if supportFields]><![endif]–>. Because of the amount of variation between the sites, it is important to use indicators of fish farm impact in vegetated and non-vegetated systems in the future. 

Are Fish Farms the Answer in Supplying Our Growing Population?

There is a great controversy surrounding production through fish farms as opposed to a reliance on wild fish sources. Wild fisheries populations are declining, however aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> could become the most sustainable source for protein for humans. Currently there is a reliance on meat from livestock, and food consumption is increasing worldwide. The population is estimated to increase from an already high 6.9 billion to 9.3 billion people by 2050. With this in mind, the question arises about where global meat will come from. Raising livestock uses up a vast amount of land, freshwater, fossil fuels, and results in organic waste and fertilizer<!–[if supportFields]> XE “fertilizer” <![endif]–><!–[if supportFields]><![endif]–> run-off that has a negative impact on rivers and oceans. These same issues apply to fish farming and other aquaculture, which results in fish sewage, depletion of mangrove forest<!–[if supportFields]> XE “forest” <![endif]–><!–[if supportFields]><![endif]–> for shrimp growth, and densely packed salmon<!–[if supportFields]> XE “salmon” <![endif]–><!–[if supportFields]><![endif]–> farms that cause disease and parasites<!–[if supportFields]> XE “parasites” <![endif]–><!–[if supportFields]><![endif]–>, which kill off their populations and infect native species as well. Larger offshore pens are much cleaner and could serve as a place for expansion of aquaculture and could even become more sustainable than wild fish or raised beef. —Lauren Lambert
Simpson, S., 2010. The Blue Food Revolution. Scientific American 304, 54–61

Simpson (2011) addresses the benefits of aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> and fish farming as a solution to the global food security issue. Coastal fish farms pollute the ocean with fish excrement and food scraps, particularly in the shallow waters. Offshore sites such as Kona Blue Water Farms have eliminated the pollution issue by submerging paddocks that are anchored in the presence of rapid currents that quickly dilute and sweep away the harmful waste before it can become a problem for marine ecosystems nearby. These paddocks are cone shape and made from solid material that is strong enough to keep sharks from getting into the fish supply. They contain massive amounts of domesticated yellowtail, which serve as an alternative to wild tuna. These fish are fed pellets of fishmeal and oil made from smaller fish. The yellowtail could survive on a purely vegetarian diet, but their meat would not contain the fatty acids and amino acids<!–[if supportFields]> XE “amino acids” <![endif]–><!–[if supportFields]><![endif]–> that produce a healthy, good tasting fish. Other farms raise seaweed and filter feeding animals such as mollusks near the fish pens to use up the waste. Cutting edge designs for fish pens are submerged, steered by large propellers, and ride on ocean currents to stimulate fish maturation. The pens would then return months later to the starting point or designated destination for delivery of fresh fish to market.
The fishmeal used to feed the fish farms is of concern because of the rapid decline of smaller fish species such as anchovy<!–[if supportFields]> XE “anchovy” <![endif]–><!–[if supportFields]><![endif]–>. Anchovy concentration in feed pellets were reduced from containing 80% in 2005 to 30% in 2008 by adding a higher concentration of soybean<!–[if supportFields]> XE “soybeans” <![endif]–><!–[if supportFields]><![endif]–> meal and chicken oil. However as the demand for fish farms increases, sardine and anchovy populations are in jeopardy of a decline in population size. Aquaculture is the fastest growing food production sector in the world, expanding at a rate of 7.5% per year since 1994. At this rate, fish and all of its products could be exhausted by 2040 and therefore, the main goal is to eliminate the use of wild fish from feed products altogether. One possible solution is to use docosahexaenoic acid (DHA) from microscopic algae because of the need to eliminate all agricultural resources from feed, and push towards a reliance on easily grown seaweed and zooplankton<!–[if supportFields]> XE “zooplankton” <![endif]–><!–[if supportFields]><![endif]–>.
The world health organization predicts a 25% increase in meat consumption by 2050. Simpson leans towards aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> for the global protein supply. Cattle eat a large amount of heavily fertilized crops, and pig and chicken farms are extremely polluting to the environment. Raising Angus beef requires 4,400 times more high quality pastureland than seafloor needed for the equivalent weight of farmed Atlantic salmon<!–[if supportFields]> XE “salmon” <![endif]–><!–[if supportFields]><![endif]–>. However fish farms also have their flaws. Areas below coastal fish farms have huge dead zones, similar to the results of fertilizer<!–[if supportFields]> XE “fertilizer” <![endif]–><!–[if supportFields]><![endif]–> run-off from the Mississippi River into the Gulf of Mexico<!–[if supportFields]> XE “Gulf of Mexico” <![endif]–><!–[if supportFields]><![endif]–>, or harmful algal blooms from pig farms in the Chesapeake Bay. Although fish farms are relatively detrimental to ecosystems, marine ecosystems have the ability to recover in less than a decade, whereas a cattle farm would take centuries to overcome the damage.
Fish farming reduces the size of marine fishing fleets, so that although fuel consumption and emissions are higher on an offshore farm, they are not as high as would result from fleets catching equivalent amounts of wild fish. Aside from these advantages, inefficient and harmful fishing methods such as trawling and dredging kill millions of animals as bycatch, that are regarded as worthless and tossed aside. Fish farming is also more efficient in that the raised fish do not have to waste energy searching for food, avoiding predators, and reproducing. Most of their diet goes into growth, so they mature at a faster rate.

Fish farming already accounts for 47% of global seafood consumption, and could potentially rise to 62% of total protein supply by 2050. Although there are many benefits to this method of food production, society is not yet ready to switch to these measures. But Americans do not yet accept this transition to an increased reliance on aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–>; the public accepts domestication on land, but has a perception of the ocean as a wild frontier. Perhaps at some point this will change. 

A Warming Climate Leads to Redistribution of Fisheries Around the World

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.

How Fisheries Respond to the Effects of Climate Change

The productivity of fisheries plays a significant factor in human society because of influences on food supply, employment, and income. The effect of climate change on marine communities is of particular importance because of the strong influences that these communities have on marine food web function and fisheries yield. Climate can effect the function, distribution, and structure of fish communities.  The distributions of fish species is expected to shift towards the poles as a result of climate change. Many studies have focused on how climate has affected abundance levels as well as the consequences of this decline. The changes in productivity of specific and whole populations will determine how these fisheries are responding to climate change. Jennings and Brander 2010 proposed that it is possible to make predictions about the community level responses to climate that are independent from knowledge about identity and dynamic of component populations. Community level approaches could be used to determine total fishery productivity, however population specific productivity will need to be based on each individual population. The fluctuation of a species population size can have negative effects in all countries. –Lauren Lambert
Jennings, Simon, and Keith Brander. “Predicting the Effects of Climate Change on Marine Communities and the Consequences for Fisheries.” Journal of Marine Systems 79.3-4 (2010): 418-26.

Jennings and Brander 2010 addresses several methods in which population and community based abundance levels change as a result of climate change. Abundance is related to total production size, so lower intercepts of size spectra in areas with low primary production means that production is reduced by a constant fraction throughout the food web. Primary production is correlated with fish production at large scales. Slopes of size spectra depend on the relative body sizes of predators and prey and efficiency of energy transfer from prey to predators. The former is measured as the mean predatory-prey mass ratio (PPMR), while the latter is mean trophic transfer efficiency (TE). Because slopes of size-spectra are constrained by these factors, the mean trophic level of the community is also constrained. Based on evidence for a relatively constant slope at a range of temperatures, it can be concluded that temperature will influence rates but will not change relative abundance at size. Jennings and Brander 2010 noted that species with faster life histories responded more rapidly to climate change. Studies also showed that smaller prey species moved while their predators did not. This could potentially disrupt the food chain if other species do not replace their absence. The effects of climate change on primary production will be the main factor driving changes in abundance and production.
Due evidence from previous publications, Jennings and Brander 2010 presented information regarding six different climate model simulations to show the response of primary production in ocean ecosystems in relation to climate change from the beginning of the industrial revolution to 2050. This provides insight to a rule-based categorization of global marine system into biogeographic production zones, estimates of change in primary production within these zones, and an overview of the limitations of making projections of ocean production. It has been suggested that global primary production may increase by 10% by 2050, however there is not much confidence in the accuracy of this estimate. Large scale plankton sampling shows actual observations of declining phytoplankton and chlorophyll levels over the past 20–50 years. This evidence is consistent with the expected consequences of reduced nutrient supply.
Over the next 4–5 decades, global marine primary production is not expected to significantly change, but there is a stronger basis for predicting changes at a regional scale particularly in the North Pacific and North Atlantic. These changes largely rely on regime scale and event scale factors such as El Niño effects. In the Arctic Ocean, a rising climate will lead to reduction in ice cover, resulting in a greater amount of phytoplankton production in these areas because of the increased availability of sunlight. While the productive area will rise, the existing food web will be disrupted. For example observations show that there has been a switch from krill to salps as the major nektonic species in some areas of the Antarctic. Increase in vertical stratification will also be a result of increased freshwater input from rivers. This is likely to result in negative consequences for fisheries and cause shifts in relative productivity of benthic and pelagic species in this size spectrum.
To assess the effects of climate change on fish communities, two methods have been proposed. Scaling up from predictions of climate on the individual species within the community could be used, or identification of aggregate properties of communities and the expected responses. Both of these approaches done simultaneously will provide the best understanding of ecological as well as community effects of climate change. Productivity of communities is likely to be predictable but species composition is not. The expected capacity to develop shipping vessel designs that allow for switching between different species will change the market in that they will need to accept and sell a more diverse range of fish and fish product. For the future, the main challenges in predicting the effects of climate change are to refine the current models for primary production at global scales as well as developing individual population based models that are consistent with community based models. Flexible ways of incorporating species dynamics in size-based models also needs to be developed.

Consequences of Climate Change for Tropical Plants in Ethiopian Mountains

Mean temperature is one of the major influences that drive species distribution, especially along an altitudinal gradient. Change in species distribution is one of the consequences of global warming because of poleward and upward shifts across a wide variety of taxa. The global distribution of biodiversity and climate change scenarios predict greater than average warming in the tropics, which results in the loss of current climate conditions. This will cause the rate of species extinctions to increase, suggesting that global warming may be one of the most serious threats to tropical biodiversity. Inner tropics species cannot adapt to climate change by latitudinal shifts because of the lack of latitudinal temperature gradient within the tropics. Plants regulate water cycle, secure slope stability, and provide microhabitats for other species. Evidence from the past provides knowledge that tropical species react to climate change by altitudinal range shifts. Kreyling et al. (2010) illustrates the potential altitudinal range shifts using a model that accounts for the expected warming by shifting the altitudinal range of species according to the shift of isotherms. Four ecological challenges were identified when applying this model to a selected study area. This includes lowland attrition, range shift gaps, range contraction, and extinction. The model was applied to a data set of altitudinal vegetation surveys in southern Ethiopia. The three hypotheses tested were (1) global warming will result in lowland attrition, range shift gaps, range contractions, and increased extinction risks of the plant species; (2) some groups of plants face a higher than average risk because of their current altitudinal distribution; (3) endangered species are most vulnerable to climate change. The study area was located in a physiologically diverse area of the southwest Ethiopian highlands.—Lauren Lambert
Kreyling, J., Wana, D. and Beierkuhnlein, C. (2010), Potential consequences of climate warming for tropical plant species in high mountains of southern Ethiopia. Diversity and Distributions, 16: 593–605

It is assumed that species that currently occupy warmer habitats at their lower range limit may be able to shift to cooler places at the same elevation as the climate warms. The model does not account for other parameters such as change in moisture or land usage but is able to identify vulnerability to warming in a given landscape.
During fieldwork, a total of 475 species belonging to 101 plant families were encountered which represented about 46% of the known species belonging to the data set of the study area. These species are predicted to be subjected to range shift gaps that are already under warming scenarios, and extinction risk will potentially increase under warming scenarios of 3.5°C or higher.
A temperature of about 1°C is predicted to increase the risks of lowland attrition and range shift gaps for the study area. If warming does exceed 3.5°C, extinction of surrounding species will become more likely. Tropical lowland species are already living at their thermal optimum. A forecast of an increase in primary productivity may lead to an increase in the frequency of fires. Since the plants existing in the study area are not adapted be fire tolerant, this will increase the extinction risk and rate of these species, and therefore will accelerate lowland attrition.
Range shift gaps are related to the speed of warming and the concern about species’ responses on the rate of warming. Species that must face range shift gaps will need to compete with the inhabitants of the new potential range. Vulnerability is particularly high for species that are restricted to narrow altitudinal ranges, especially those that are at high altitudes. For example, the fern growth form appears to be more susceptible to climate change than others because it is restricted to high altitudes. This evidence is in contrast to what is found in cloud forest transects, suggesting that differences in vulnerability are regionally specific. Herbs and ferns are predicted to be the most affected by climate change, and plant families with high species richness are more resilient to extinction because of their numbers. The potential response of species belonging to Fabaceae and Poacae might have a negative reaction to global warming. This is of concern because of their economic and ecological importance. The loss of these species may result in the loss of nitrogen fixation and range resources in lowland semi arid ecosystems of the tropics.
          The adaptation policies in Ethiopia are focused on agricultural production, encouragement of shifting management strategies, and changing target crops (Bryan et al. 2009). It is a definite possibility that the agricultural zone will move upslope faster than the species can adapt to. The habitat may not be suitable for existence of these species in that zone. For example, the soil might not be developed to a point that is required by these species that are moving into the zone. The process is extremely slow and climate change is increasing the speed of upward shift. This is expected to lead to an increase in extinction rick and decline in population size and phenotypic diversity of the inhabitants.
          It is apparent that global warming is a threat to tropical biodiversity and that lowland attrition is emerging as an urgent challenge of importance in the tropics. It is unclear to what extent lowland species are able to tolerate a warmer and drier climate than they are currently experiencing, but altitudinal shift as a result of climate change is in fact a risk that all species must take.