One can find it in pasta, after popcorn, and at Panda Express; it fries rice, is in finger food, and is found across the world. The list goes on: data shows that shrimp is one of the most popular marine creatures, so much so that in 2014, it was recorded as the most consumed marine animal by Americans (GLOBEFISH, 2020). Approximately 4.60 pounds of shrimp are consumed per capita in the United States (National Oceanic and Atmospheric Administration, 2020), and they are not alone: Japan and Europe, especially the former, dominate global shrimp consumption, and developed countries make up 70% of all shrimp consumed worldwide (Puk et al., 2023). Since industrialization, shrimp have taken the world by storm; and, for the past century, it has been at a deadly cost. Among many of the problems that reared in 1990 onwardsβincluding rampant human population growth and animal disease within and out of aquaculture systemsβone prominent consequence is the rapid loss of mangroves.
History of Philippine Aquaculture
Although commercial shrimp farming was recorded as early as in the 1940s in Asia and the Philippines, the industry did not develop for approximately 40 years. This changed in the 1980s, when Taiwanese developments in and exportation of aquaculture technology, as well as a commercial interest in shrimp, initiated a worldwide phenomenon dubbed βShrimp Fever.β Adjusted for inflation, during the 1980s, domestic shrimp in the United States sold for approximately 4.50 USD per poundβa lucrative price magnified in other countries and in exportation prices (Haddad & Lively, 2019). Attracted by the rising prices, tropical countries rushed accordingly to monopolize a burgeoning commercial shrimp industry (BRIEFLY, 1999). This phenomenon coincided with the βBlue Revolution:β a period of maricultural and aquacultural development and economic growth that began in the mid-nineteenth century and bolstered the technological developments of marine animal and plant cultivation (Neushul & Badash, 1998). Some of the most successful countries during this overlapping period include the Honduras and Ecuador (Persoone & Sorgeloos, 1982), in the Central and South American regions, and China and Indonesia, in the Southeast Asian region.
The Philippines is one of many countries affected by this economic revolution, and it even possesses a storied hold on the marine economy of Southeast Asia. While no longer the third highest producer of cultivated shrimp as it was in the 1990s (Teves & Ragaza, 2014), the Philippines still relies greatly on its fishery sector. Today, the agricultural sector contributes approximately 20% of the Philippines Grand Domestic Product (GDP); its fishery sub-sector accounts for 15% of the total sector contribution (Balakrishnan). This sub-sector is the fifth highest increasing sub-sector in the Philippines, comparable to other agriculture and foresting sub-sectors, which account for the third highest decreasing economics sub-sectors (Mapa, 2023). In 2004, 26% of the fishery sub-sector comprised of aquaculture workers, compared to 65% involved in municipal fishing and six percent in commercial fishing (Balakrishnan). Conversely, it contributed most to the sub-sector, supplying 52.4% of its production, versus the 26.8% and 20.8% contributed by municipal and commercial fishing respectively (Teves & Ragaza, 2014).
The high production of the aquaculture sub-sector has been supported by the Philippines government since 1947, when the Bureau of Fisheries and Aquatic Resources was founded and set aside 23.6 million USD to construct and run aquacultural fishponds. It was also bolstered by the 1984 Aquaculture Development Project, a shrimp pond and shrimp hatchery project financed by a regional bank known as the Asian Development Bank for 21.8 million USD (Primavera, 1995). As a result, in the Philippines alone, production increased by 40,000 metric tons between the 1970s and 1980s: almost twice the increase between the 1960sβ1970s and four times that of the 1940s-1950s (Primavera, 1995).
Human Impacts
Although four decades have passed since the era of βShrimp Fever,β the commercial demand of shrimp has only increased. Fish consumption has increased at twice the rate of the growth of the worldwide population (International Union for Conservation of Nature, 2020); both have increased in tandem in their own ways. By 2020, over three billion people worldwide relied on seafood production for nutrition (World Wildlife Fund, 2023). In response, over 20.5 million people work in regional aquacultural sub-sectors, of which 95% work in Asia (Gee, 2020), and since 2000, the production of shrimp has grown by 10% per year (World Wildlife Fund, 2012). One analysis in 2019 declared despite setbacks caused by the COVID-19 pandemic, 4.5 million tonnes of shrimp were farmed that year, with 85% derived from the Southeast Asian region (GLOBEFISH, 2020).
To fulfill commercial demand, areas in the tropical coastal regions are cleared to convert into usable space for shrimp ponds and shrimp farms. Mangals, coastal forests with soft, muddy sediment, high salinity, and intense wave action, are inhabited by mangroves: flowering plants with thick anatomy that extends to their roots, branches, and leaves. This anatomy reduces water loss and protects organisms that shelter in mangrove plants (Castro & Huber, 2023) but obstructs shrimp farmers who seek to use the brackish water for cultivation (World Rainforest Movement, 2001b). The brackish conditions are advantageous for shrimp farming. As a result, they are the second most common environment for Philippine species cultivation (Teves & Ragaza, 2014) and are acquired by clearing mangals. Historically, mangals bordered approximately 75% of tropical coastlines; however, nearly half of them (Aronson, 2020) have been cleared to accommodate for wide fishponds, especially flat and thin in the Philippines, that can span up to 20 hectares, or 200,000 square meters (Kungvankij et al., 1986).
Philippine shrimp ponds are affected by intense contamination due to the treatment of the cultured species. Philippine wild shrimp fry are artificially stocked in closed pond systems at an average of 2,000β5,000 fry per hectare (Kungvankij et al., 1986) and are given feed of poor quality. This feed frequently remains uneaten; it sinks to the pond bottom and slowly decomposes, inducing higher levels of organic content, ammonia, and nitrite, and reducing the supply of oxygen present (Corre, 1993). The high concentration of cultivated shrimp also increases the risks of disease and parasites within the pool, encouraging shrimp farmers to use antibiotics and pesticides and leading to the release of chemicals into the pool systems (Monterey Bay Aquarium, 2020). Overall, these shrimp ponds can generate high concentrations of waste and nutrients. This waste is flushed into nearby systems, including remaining mangals and the nearby sea (Castro & Huber, 2023). When the waste and nutrient concentration is too high, these ponds are abandoned, and the mangrove environments used to create them are neglected as well (Bertness et al., 2001).
Philippine shrimp farms are created in close capacity and crowded near river channels and tidal creeks used to empty local drainage systems. These systems are overloaded by the addition of organic waste from shrimp farms (Corre, 1993). They also face competition from large business trawlers, who trespass into prohibited zones for industrial fishing, and overcompete against smaller municipal fisheries in the same areas. Fisheries with less indiscriminate methods generate high levels of bycatch, increased due to their location in a poor tropical region and including finfish and turtle bycatch (Gillett, 2008).
Consequences of Human Impacts
The rapid development of shrimp fisheries in the wake of the βShrimp Feverβ has impacted many aspects of the globe, but the mangals are one of the most documented. Many do not care about the deforestation of mangals, as they are viewed as brackish wastelands or uninhabitable swamps. This perception and a growing tendency towards utilizing these habitats for shrimp farms has culminated in the destruction of one percent of mangals per year (Zoological Society of London, 2023). Imperatively, without action, all mangroves on Earth will be destroyed by the end of the century (Puk et al., 2023). The rapid destruction of mangroves cascades into several other consequences for both the environment and humans who impact them. Coral reefs that connect to mangals host rare corals that are protected from heat and ultraviolet radiation by the shade of flowering mangrove plants (Zoological Society of London, 2023). Losing both these reefs and forests exposes the Philippines to both higher risks of being affected by tropical disasters and an increased risk of higher severity (Martin, 2018). These disasters include tsunamis, sea surges, storms and monsoons, and typhoons; one notable example is Typhoon Haiyan or Typhoon Yolanda. Mangroves provide stability and protection against wave action, including those caused by typhoons; Typhoon Haiyanβs impact, as well as other weaker typhoonsβ, are noted to have worsened due to the clearance of these natural barriers.
The increased pollution of shrimp farms has led to poor water quality (Corre, 1993) and eutrophication resulting from chemical discharge and runoff. Cultivated shrimp and their ponds are drowned in waste (World Rainforest Movement, 2001a) and fecal contamination; the contamination contains ammonia and nitrite in sub-lethal concentrations, the products of the removal of amines from protein in the shrimp feed and excrete. This pollution can even escape the mangrove habitat and reach as far as one kilometer away from its place of origin (Corre, 1993). Conversely, the clearance of mangals leads to the release of high concentrations of carbon dioxide contained in their leaves and the sediment (Castro & Huber, 2023). The soil and leaves can store three to four times the amount of carbon that tropical forests can (Aronson, 2020), and in 2000, a sample of mangrove soil was recorded to store ~6.4 billion metric tonnes of carbon (Zoological Society of London, 2023). As a result of their decreasing abundance, the decay of cleared mangroves accounts for roughly 10% of the carbon dioxide emissions caused by deforestation (Castro & Huber, 2023). Furthermore, former mangrove habitats are noted as difficult to impossible to replant and restore: chemical runoff and exposure to sub-lethal concentration of nutrients transforms the mangrove soil, making it highly reductive and composed from high levels of acid-sulfate (Bertness et al., 2001).
Even other species are affected by the destruction of mangrove forests and construction of shrimp fisheries. Many endangered, endemic species of birds shelter in mangroves alongside several aquatic and euryhaline plants and organisms that need mangrove systems to survive (Viray-Mendoza, 2017). Additionally, many shrimp bycatch are endangered, keystone species, or severely impacted by shrimp fisheries. Trawls catch sharks, skates, rays, and other predators to shrimp indiscriminately, causing fluctuations in the ecosystem and endangering vulnerable species (Gillett, 2008). And shrimp themselves are imperiled by the conditions of shrimp fisheries: organic matter accumulates in the shrimp ponds without being properly cleaned and disposed of, harming the growth and health of shrimp cultures. In one study, no matter how low or high the density of shrimp tock was within the pond, shrimp developed in body weight faster when a pond was initially constructed than their later counterparts by thirty days minimum (Corre, 1993). Shrimp cultures are also susceptible to outbreaks of diseases and infections; one example is Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV,) a virus with a high mortality rate for shrimp and mutation rate that affected many fisheries in the Western Visayas region in the early 1990s.
Mitigating the Consequences
Though the deforestation of mangroves is dangerous and continues to worsen, things can and are still being done to prevent their complete destruction by the centuryβs end. Due to the prevalence of shrimp farms across the globe and the far-reaching effects of fisheries and mangals both, many things can be done by both individuals and organizations to avoid this fate.
For one, involved farmers can take better care of the shrimp themselves within the existing farms. Improving the quality of shrimp feed, pond water, soil, and dynamics within the shrimp ponds will reduce the amount of excess uneaten nutrients in the ponds. This in turn lowers the sub-lethal levels of chemicals within and disposed from the pond, the need to add additional chemicals to the farm through antibiotics and pesticides, and the risks of disease within the culture, among much more. Following analyses conducted by Valeriano Corre, Jr., Corre also recommends stocking and cultivating shrimp only at certain periods of the year, exchanging them with animals such as milkfish to reduce stress on used watersheds, decrease the use of resources through the year, and increase the survival rate and yield of shrimps compared to cultivating shrimp through the full year (Corre, 1993). Farmers can also better manage the disposal of wastewater and moderate their usage of antibiotics (Monterey Bay Aquarium, 2020).
Individual fisheries are also growing aware of their effect on the mangrove habitat and are taking measures to ensure their shrimp are caught without endangering the ecosystem, the coast, the ocean, and their farms and customers. At present, three shrimp farms within the Philippines possess certification with the Aquaculture Stewardship Council (Aquaculture Stewardship Council International, 2023a) and follow in the footsteps of the first Philippine tuna fishery to gain certification with the matching Marine Stewardship Council in 2018 (Marine Stewardship Council, 2021). These councils discourage the consistent use of wild fish as feed and antibiotics while advertising certified products as organic, premium, antibiotic and chemical-free, and ultimately sustainable in a rapidly deteriorating world (Aquaculture Stewardship Council International, 2023b).
Organizations both connected and disconnected from the Philippine government are working to restore mangrove forests deforested for aquaculture and industrialization. They work under the belief that shrimp not only have everything necessary for proper development within natural mangrove habitats, but will produce better yield, prices, and practices if cultivated in their natural, uncleared habitats (Gee, 2020). As an example, one town in the Bicol region, Prieto Diaz, is reaping the rewards of a mangrove restoration project funded by the Department of Environment and Natural Resources. The forest stretches 1,034 hectares and is credited as both the largest and healthiest mangrove ecosystem within its region, featuring a high biodiversity and capacity for natural regeneration. The town has support from two local groups: Seagrass, Mangroves, Corals and the Malipot-Rawis-Lagbak Fish Sanctuary and Marine Reserve, who possess stewardship over the forest (Conde, 2023). Charities such as the Zoological Society of London also assist in replanting and restoring mangroves from abandoned shrimp ponds, as well as researching mangrove ecology, protecting mangroves as βMarine Protected Areasβ (MPAs,) and changing the public perception of mangroves through media and communication (Zoological Society of London, 2023).
The Philippine government itself has slowly begun to take action to preserve mangrove forests. This year, the House of Representatives passed House Bill No. 7767, a set of mandates emphasizing funding and overseeing endangered Philippine coastal ecosystems, and is waiting on the Senateβs vote on a matching bill (Oceana, 2023). The bills are supported by active campaigns by global organizations such as Oceana and sponsored by Senators within the current government.
Even individuals outside of organizations and fishery employment can make a difference. As long as farming and catching regulations and practices remain unclear, individuals should avoid buying shrimp imported from the Philippines (Monterey Bay Aquarium, 2023). Generally, seafood should only be bought if source farmed, certified, or identified by credible sources that can verify a supplierβs interest in mangrove ecosystem protection (Aronson, 2020). Outside of buying seafood for personal cooking, individuals should inquire at restaurants and spread awareness of sustainable farming and buying methods for shrimp (Weis, 2020).
Although these methods may seem small, change is still possible. Over a million mangroves have been replanted by ZSL alone in the past sixteen years (Zoological Society of London, 2023), and communities have been motivated to steward and restore local mangroves through the βBlue Revolution.β The globe has time to protect the mangroves of the Earth and protect both ecosystems and civilizations in turn. As climate change and rising environmental issues wrack the planet, mangroves grow more and more importantβand saving them before the end of the century nears grows just as important all the while.
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