Seagrass production around artificial reefs is resistant to human stressors
Artificial reefs might help to restore the ocean’s ability to fight against climate change. The reefs boost the productivity of seagrass meadows by attracting fish, which can improve the ability of these habitats to lock up more carbon dioxide beneath the waves. Breeze blocks placed in one of the ocean’s most endangered habitats provide an unexpected lift for fish. Seagrass meadows are found across the world, reaching from the tropics up into the lower reaches of the Arctic circle. They are incredibly valuable habitats, providing a nursery for young fish as well as sucking vast quantities of carbon dioxide from the atmosphere. However, with an area of seagrass the size of a football pitch being lost every 30 minutes, it’s more important than ever to find out how to turn things around. A new study in the Caribbean has shown that artificial reefs can help to bolster their growth in the tropics, even as threats such as fishing and nutrient pollution continue. Dr Jacob Allgeier, a co-author of the paper, says, ‘By attracting fish, whose faeces provide concentrated nutrients for the seagrass, the artificial reefs increase the primary production of the entire ecosystem.’ ‘We are now investigating how this cascades up the food web. The new energy has to go somewhere, so we are quantifying how it affects invertebrates and fish with our evidence suggesting that it is fuelling increases in both.’ The findings of the study were published in Proceedings of the Royal Society B. Artificial reefs and seagrass One of the biggest issues affecting seagrass is nutrient pollution, often from the release of human sewage. While the influx of nutrients can initially boost the growth of the meadows, it also promotes the growth of algae which reduces the amount of sunlight getting to the seagrass and harms it in the long run. Alongside fishing which causes levels of the fish faeces that fertilise the meadows to drop, it was thought that the combination of these two issues might work in unexpected ways to hinder the growth of seagrass. But the current study has revealed some surprising results. It has found that the productivity of seagrass in both disturbed and undisturbed meadows was increased by the presence of an artificial reef, while algae didn’t actually seem to pose an issue, even in areas where nutrient pollution was high. Mona Andskog, the PhD student who led the research, explains, ‘Artificial reefs built in seagrass create a positive feedback loop. They attract fish that use the reefs for shelter which, in turn, supply new nutrients from their faeces that fertilise the seagrass around the reef.’ ‘This increased primary production can increase invertebrate production by providing more food and shelter for invertebrates, which in turn provide more food for fishes.’ Experiments in Haiti, at some of the most fished sites included in the study, also showed that the artificial reefs were providing additional benefits to the fish. Large numbers of small fish were found at the site because of the difficulty in using nets around the reef, meaning that the overall biomass of fish was at times larger than in unfished areas measured elsewhere in the study. While artificial reefs present a promising option for tropical seagrasses, they’re likely to have a much more limited impact on temperate meadows. These waters already tend to have higher nutrient levels, meaning that any contribution the reef would made to overall growth would be small. The scientists now hope to explore how the placing of artificial reefs can affect seagrass ecosystems, as well as expanding their research to the Dominican Republic. ‘We will be testing how different configurations of artificial reef clusters can affect the production and fish community composition,’ Jacob says. ‘This includes the number of artificial reefs in each cluster, as well as their arrangement.’ ‘As with this research, we hope to simultaneously use the reefs to test fundamental questions about production in these highly impacted ecosystems as well as optimising the positive feedback that is initiated by the artificial reefs.’ More information: Mona A. Andskog et al, Seagrass production around artificial reefs is resistant to human stressors, Proceedings of the Royal Society B: Biological Sciences (2023). DOI: 10.1098/rspb.2023.0803 This story is republished courtesy of Natural History Museum. Read the original story here.
Green sea turtles have traveled to the same seagrass to eat for 3,000 years
For approximately 3,000 years, generations of green sea turtles have returned to the same seagrass meadows to eat. This was discovered by Willemien de Kock, a historical ecologist at the University of Groningen, by combining modern data with archaeological findings. Sea turtles migrate between specific breeding places and eating places throughout their lives–this much was known. But the fact that this stretches over many generations highlights the importance of protecting seagrass meadows along the coasts of North Africa. The results were published in PNAS on July 17. When young green sea turtles hatch, their parents have already left for a long journey. The little turtles clumsily make their way off the beach into the ocean and, not yet able to navigate the long migration of their parents, float around for years. During this time, they are not very picky eaters, omnivores even. Then, at about five years of age, they swim to the same area where their parents went, to eat a herbivore’s diet of seagrass. Along the coasts of the eastern Mediterranean Sea, volunteers are active to protect the nests of the endangered green sea turtles. However, as Willemien de Kock explains, “We currently spend a lot of effort protecting the babies but not the place where they spend most of their time: the seagrass meadows.” And crucially, these seagrass meadows are suffering from the effects of the climate crisis. Analyzing sea turtle bones In the attic of the Groningen Institute of Archaeology at the University of Groningen, De Kock had access to boxes full of sea turtle remains from archaeological sites in the Mediterranean Sea area. The excavations were already done by her supervisor, Dr. Canan Çakırlar. “All I had to do was dig in some boxes,” De Kock says. By analyzing the bones, De Kock was able to distinguish two species within the collection of bones: the green sea turtle and the loggerhead turtle. De Kock was also able to identify what the sea turtles had been eating. This relied on a substance called bone collagen. By inspecting the bone collagen with a mass spectrometer, De Kock could detect what kind of plants the sea turtles must have eaten. “For instance,” De Kock explains, “one plant might contain more of the lighter carbon-12 than another plant, which contains more of the heavier carbon-13. Because carbon does not change when it is digested, we can detect what ratio of carbon is present in the bones and infer the diet from that.” Combining old and new Modern satellite tracking data from the University of Exeter then provided De Kock with information on the current traveling routes and destinations of sea turtles. Researchers from Exeter had also been taking tiny samples of sea turtles’ skins, which revealed similar dietary information as De Kock found in bones. De Kock was, therefore, able to draw conclusions, connecting diets of millennia ago to specific locations. She found that for approximately 3,000 years, generations of green sea turtles have been feeding on sea grass meadows along the coasts of Egypt and West Libya. The results for loggerhead turtles were less specific because they had a more varied diet. So, why is it relevant to know the eating habits of a species over many past generations? Because we collectively suffer from the shifting baseline syndrome: slow changes in a larger system, such as an animal population, go unnoticed because each generation of researchers redefines what the natural state was, as they saw it at the start of their careers. “Even long-term data goes back only about 100 years,” says De Kock. “But tracing back further in time using archaeological data allows us to better see human-induced effects on the environment. And it allows us to predict, a bit.” In fact, recent models have shown a high risk of widespread loss of seagrass in precisely these spots where green sea turtles have been going for millennia. This could be detrimental to the green sea turtle, precisely because of its high fidelity to these places. More information: de Kock, Willemien, Threatened North African seagrass meadows have supported green turtle populations for millennia, Proceedings of the National Academy of Sciences(2023). DOI: 10.1073/pnas.2220747120 Story provided by University of Groningen
Caribbean seagrasses provide services worth $255B annually, including vast carbon storage
Discussions of valuable but threatened ocean ecosystems often focus on coral reefs or coastal mangrove forests. Seagrass meadows get a lot less attention, even though they provide wide-ranging services to society and store lots of climate-warming carbon. But the findings of a new University of Michigan-led study show that seagrass ecosystems deserve to be at the forefront of the global conservation agenda, according to the authors. It’s the first study to put a dollar value on the many services—from storm protection to fish habitat to carbon storage—provided by seagrasses across the Caribbean, and the numbers are impressive. Using newly available satellite data, the researchers estimate that the Caribbean holds up to half the world’s seagrass meadows by surface area, and it contains about one-third of the carbon stored in seagrasses worldwide. They calculated that Caribbean seagrasses provide about $255 billion in services to society annually, including $88.3 billion in carbon storage. In the Bahamas alone, the ecosystem services provided by seagrasses are valued at more than 15 times the country’s 2020 gross domestic product, according to the study published online June 21 in the journal Biology Letters. “Our study is the first to show that seagrass beds in the Caribbean are of global importance in their areal extent, in the amount of carbon they store, and in the value of the economic services they provide to society,” said study lead author Bridget Shayka, a doctoral student in the U-M Department of Ecology and Evolutionary Biology. “The findings underscore the importance of conserving and protecting these highly threatened and globally important ecosystems, which are critical allies in the fight against climate change.” One way to prioritize seagrass conservation would be to include those verdant undersea meadows in global carbon markets through projects that minimize loss, increase areal extent or restore degraded beds. The idea of selling “blue carbon” offset credits, which monetize carbon stored in coastal and marine ecosystems, is gaining traction for several reasons. For one, many island nations that have already been impacted by climate change—through increasingly intense hurricanes or rising sea levels, for example—have large areas of valuable coastal ecosystems that store carbon and that provide other services to society. Blue carbon (the name refers specifically to carbon stored in coastal and open-ocean ecosystems while “green carbon” refers more broadly to carbon stored in all natural ecosystems) offset credits could be a way for wealthier countries to compensate for their contribution to human-caused climate change while at the same time benefiting the economies of impacted countries and helping to conserve coastal ecosystems, which are among the most impaired in the world. Threats to seagrass meadows include coastal development, chemical pollution, recreation, shipping and climate change. “Because seagrass ecosystems are both highly important for carbon storage and sequestration, and are highly degraded globally, they represent an important burgeoning market for blue carbon,” said marine ecologist and study senior author Jacob Allgeier, an associate professor in the U-M Department of Ecology and Evolutionary Biology. “Yet, to date, a fundamental impediment to both evaluating seagrass and promoting it in the blue carbon market has been the lack of thorough seagrass distribution data.” For their study, the U-M-led team used newly available seagrass distribution data collected by the PlanetScope constellation of small DOVE satellites. They classified Caribbean seagrass ecosystems as either sparse or dense and estimated the amount of carbon in plants and sediments using data from Thalassia testudinum, the dominant seagrass species in the region. The researchers then calculated a conservative economic value for the total ecosystem services provided by seagrasses in the Caribbean and for the stored carbon, using previously published estimates for the value of services including food production, nursery habitat for fishes and invertebrates, recreation and carbon storage. Grouper, queen conch and lobster are among the commercially harvested animals that rely on Caribbean seagrass. Green sea turtles, tiger sharks and manatees also depend on it. To estimate the dollar value of the carbon stored in Caribbean seagrass beds, the researchers used $18 per metric ton of carbon dioxide equivalents, borrowed from California’s cap and trade program. In addition to Caribbean-wide estimates, the researchers calculated values for individual countries in the region: The Bahamas has the largest share of Caribbean seagrass (61%), providing total ecosystem services valued at $156 billion annually, including $54 billion in carbon storage. Cuba ranks second in areal seagrass coverage (33% of the Caribbean total), with a value of $84.6 billion per year for all ecosystem services, including $29.3 billion for carbon storage. The dollar value of the carbon in seagrasses around Cuba is equivalent to 27% of the country’s 2020 GDP. “Importantly, the degradation of seagrass beds often leads to erosion and sediment resuspension, which can create a positive feedback of increased seagrass loss and the release of C stored in sediments,” the authors wrote. “Blue carbon finance thus represents a potential mechanism by which the global community can invest in conserving and protecting these vital ecosystems.” More than 60 species of seagrasses grow in shallow coastal waters around the world. They evolved from land plants that recolonized the oceans 70 to 100 million years ago. In a separate paper accepted for publication in the journal Proceedings of the Royal Society, Allgeier and colleagues show that the construction of artificial reefs in the Caribbean can help protect seagrass ecosystems from human impacts, including nutrient pollution and overfishing. Seagrasses use photosynthesis to pull carbon dioxide from the atmosphere, then store the carbon in plant tissues. The seagrasses are quickly inundated by sediments, slowing decomposition. As a result, more than 90% of the carbon stored in seagrass beds is in the top meter of sediment. Caribbean seagrasses and associated sediments store an estimated 1.3 billion metric tons of carbon, according to the new study. That’s a big number, but it’s just 1.09% of the carbon contained in above- and below-ground woody biomass in the Amazon, and just 1.12% of the carbon in the biomass and soils of the world’s temperate forests, according to the new
Fauna return rapidly in planted seagrass meadows, study shows
A study of eelgrass meadows planted by researchers from the University of Gothenburg shows that fauna return rapidly once the eelgrass has started to grow. Already after the second summer, the biodiversity in the planted meadow was almost the same as in old established eelgrass meadows. Eelgrass meadows have declined heavily in southern Bohus county in recent decades and in many places have disappeared altogether. Researchers at the University of Gothenburg have been working on the restoration of eelgrass meadows for twelve years. These meadows are important for biodiversity, as the eelgrass serves as habitat or nursery for young cod, crabs and shrimps for example. In a new study, the researchers have evaluated how rapidly replanted eelgrass gets populated by various invertebrates. The study has been going on for over two years in a bay near Gåsö island just west of Skaftö in Bohus county, and the findings are very positive. The researchers counted the abundance of invertebrates that live or burrow in bottom sediments or on the surface of bottom sediments. Size less important “The recolonization has been very rapid. After the first three-month growing season, up to 80 percent of the invertebrates had returned to the newly planted eelgrass,” says Eduardo Infantes, marine biologist at the University of Gothenburg. During the summer in 2019, the researchers planted the eelgrass shoots in four test plots of different sizes on the seabed, and with different spacing between the shoots. According to the researchers’ observations in autumn 2020, size has played less of a role in the recovery of biodiversity in the eelgrass meadows. In fact, even if the eelgrass has not had time to grow to the same density as in an established eelgrass meadow, the biodiversity is similar after only two growing seasons as in a reference area of preserved eelgrass in the same bay. Even smaller patches embedded within larger restoration plots showed good results. Their findings were reported in the journal Restoration Ecology. Can save money “This is good news for future restorations and new plantings of eelgrass meadows. We can plant new smaller plots with fewer shoots and this saves money because this is an expensive method for restoring biodiversity on the seabed,” says Eduardo Infantes. Eelgrass meadows have multiple functions that make it imperative to protect them. In addition to their important role in the coastal ecosystem, eelgrass roots bind the sediment and prevent erosion and limit resuspension of sediment in the water. More information: Karine Gagnon et al, Rapid faunal colonization and recovery of biodiversity and functional diversity following eelgrass restoration, Restoration Ecology (2023). DOI: 10.1111/rec.13887
Why saving the world’s seagrass is part of the most important to-do list in the history of humankind
“The downward trajectory of the world’s seagrass meadows must be reversed if we are to fight the planetary crisis” say leading seagrass scientists. The United Nations Sustainable Development Goals have recently been described as “the most important to-do list in the history of humankind”. Scientists from Project Seagrass and Swansea University have this week published a unique review that demonstrates how this “To-Do List” of Sustainable Development Goals provides a blueprint for achieving the net recovery of seagrass ecosystems. Conserving and restoring seagrass meadows contributes to achieving 16 out of the 17 Sustainable Development Goals. Recognising this wide role of seagrass meadows in helping achieve humanity’s ‘to-do list’ and thinking beyond their value in carbon sequestration and storage is critical to achieving the recovery of these degraded ecosystems. The call for urgent action comes after a review into the status of seagrass ecosystems and the major ecological role that they play in the coastal environment published in the leading academic journal Science and written by experts at the marine conservation charity Project Seagrass and Swansea University. Seagrass meadows are being increasingly looked to as a climate solution. However, seagrass ecosystems are sensitive to stressors and remain threatened across the globe. These degraded seagrass ecosystems are less effective at supporting biodiversity and tackling climate change. The authors state “Society needs to create meaningful pathways to net gain at local to global scales. Bold steps are needed through improved legal instruments to halt damaging factors such as bottom trawling, prevent use of damaging boating activities and to apportion responsibility for poor water quality that is causing the slow death of seagrass globally”. By recognising that seagrass meadows contribute to finding solutions to global problems such as food insecurity, water quality, wellbeing and gender equality, as well as the more well known issue such as biodiversity loss and climate change there becomes a more holistic view as to the benefits of taking large cumulative levels of action at local, regional and global scales. We need local and regional authorities to create a baseline of where seagrasses are now, where they used to be and where in the future they could be allowed to recover and be restored to get seagrass on the path to recovery. This needs to occur within the next decade if we are to fight climate change, to fight the biodiversity crisis, protect our coastlines and maintain global food security. Richard Unsworth (lead author) said “The world needs to rethink the management of our coastal environment that includes realistic compensation and mitigation schemes that not only prevent damage, but also drive the restoration, enhancement and creation of seagrass habitat. We also need a major shift in how we perceive the status of our marine environment by examining historical information, not just recent ecological baselines”. Ben Jones, a fellow author of the study added, “It is vital to work collaboratively as it is only through utilising scientific environmental studies and working as cogs in a global partnership for seagrass that meaningful change can happen”. Seagrass conservation faces substantial ecological, social and regulatory barriers and requires strong cross-sectoral partnerships to be put on the path to recovery. Identifying the solutions to seagrass conservation and restoration has never been more urgent and is critical to fight the planetary emergency. This can be achieved by using the Sustainable Development Goals as a blueprint towards recovery. Read the paper here.
Seagrass meadows are reliable fishing grounds for food
A new study shows that seagrass fisheries provide a reliable safety-net for poor fishermen, since they perceive those habitats to maintain large fish catches over time. Surprisingly, even more so than coral reef fisheries, which people normally associate with small-scale fishery. Seagrass meadows are routinely used as a fishing habitat across the Indo-Pacific region to sustain millions of households by providing fish and other animals for food and income from fishing. A new study in Ocean and Coastal Management investigated how and why households use seagrass meadows across Cambodia, Tanzania, Sri Lanka and Indonesia in the Indo-Pacific region by conducting interviews that asked what habitats they used and which they preferred. Benjamin Jones, director of Project Seagrass and PhD student at the Department of Ecology Environment and Plant Sciences, Stockholm University, says: “Seagrass was the most common habitat used for fishing. Nearly half of all households we talked to preferred fishing in seagrass over other habitats such as coral, mangroves, open ocean, mud and rock for example. This was surprising because most people think of reef fisheries as the key tropical small-scale fishery, but we show that its actually engagement in seagrass fisheries that are much more characteristic of households.” When the researchers asked the fishermen why they preferred seagrass, they expressed a general feeling of reliability: seagrass meadows always provide large catches and fish and invertebrates are always found there. This is likely due to the ecological role that seagrass meadows play for fish. They provide valuable nursery habitats with lots of places for fish to hide and grow which means that there is often a high abundance of fish present. The study also revealed that 3 in 20 people across the region were reliant on seagrass meadows as their fishing ground and did not fish anywhere else. The research from households in 147 villages also revealed that reliance on seagrass meadows was strongly influenced by household income: “Household income had two different effects. On one hand, poorer households were less likely to own motorboats. These were reliant on seagrass as they were unable to fish elsewhere, seagrass is close to shore and easy to access without a motor. On the other hand, wealthier households were more likely to own certain types of fishing gear that incentivized them to use seagrass due to high rewards and low effort requirements. These were static fishing fences that don’t require a fisherman to be present” says Benjamin Jones. Study co-author and fellow Project Seagrass director Leanne Cullen-Unsworth, says “Our results highlight the need for empirical household scale data for management of seagrass meadows. People use and value seagrass for many different reasons so safeguarding seagrass is vital to ensure that all people, all of the time, have equitable and equal access to the resources seagrass provides.” The study was a collaboration between scientists from Stockholm University, Project Seagrass, Swansea University, Uppsala University, Hasanuddin University, among others. Open Access paper: Jones, B.L.H.; Unsworth, R.K.F.; Nordlund, L.M.; Eklöf, J.S.; Ambo-Rappe, R.; Carly, F.; Jiddawi, N.S.; La Nafie, Y.A.; Udagedara, S.; Cullen-Unsworth, L.C. Dependence on seagrass fisheries governed by household income and adaptive capacity. Ocean & Coastal Management 2022, 225, doi:10.1016/j.ocecoaman.2022.106247.
Mosquito nets: Are they catching more fishes than insects?
Mosquito nets designed to prevent malaria transmission are used for fishing which may devastate tropical coastal ecosystems, according to a new scientific study. The researchers found that most of the fish caught using mosquito nets were smaller than a finger and potentially collect hundreds of individuals. Malaria is a serious global health issue, killing nearly half a million people every year worldwide. Aid organisations like the Bill and Melinda Gates Foundation have invested in solutions to solve the crisis such as distributing hundreds of thousands of bed nets to protect people from mosquito bites carrying the virus. “Distributed mosquito nets are intended to be used for malaria protection, yet communities living in poverty use them for fishing, providing fresh concerns for already overfished coastal ecosystems, says,” Benjamin Jones, a director of Project Seagrass and PhD researcher at Stockholm University Department of Ecology, Environment and Plant Sciences. There are few studies that investigate how much fish mosquito-net fishing potentially harvests, although the use of mosquito nets for fishing is not a new phenomenon: “No evidence on the sheer amount of fish that these fisheries extract has been published that we are aware of. Gaining an understanding of these catches is vital if we are to manage such fisheries,” says Benjamin Jones. In Mozambique, each sweep of the mosquito net caught more than half of the average daily catch (2.4 kg a day) using traditional nets, by weight. But many of the fishes were very small, which means mosquito net fishers who cast their nets many times each day are removing a huge number juvenile fish to eat. Many of the species caught are important for food in the region when adults or help keep the seagrass ecosystems where they are found healthy. “The use of mosquito nets for fishing may contribute to less food availability, greater poverty and the loss of ecosystem functioning,” concludes Dr Richard Unsworth, a co-author and Lecturer in Marine Biology at Swansea University. Finding a solution to the problem is incredibly hard, but the researchers suggest the need for marine scientists, social scientists, health professionals and fishing communities to all work together. Laws imposed from governments make the use of mosquito nets for fishing illegal in some localities, however, such mechanisms are evidently insufficient because people still need food and “need re-thinking” according to the study. “We need to know why communities aren’t using these nets for intended use, and therefore we have to involve them, so they can be part of developing solutions to these challenges,” says Richard Unsworth. The team collected data at seagrass meadows by ten coastal villages in northern Mozambique. Identifying each fish species, the researchers recorded the weight of each fish group and the total catch, as well as age and where they are positioned in the food web. The open access paper – “The perverse fisheries consequences of mosquito net malaria prophylaxis in East Africa” – is published on Monday 11th November at https://doi.org/10.1007/s13280-019-01280-0
Global fisheries threatened by loss of seagrass
Seafood consumption is both a love and a necessity for hundreds of millions of people all across the world. And the supply of seafood is a key part of maintaining food security for the whole planet. But as demand for seafood is increasing, stocks of wild fish and invertebrates (such as mussels and prawns) are declining. A major problem is that policies and plans designed to ensure the sustainability of our fisheries almost exclusively target fishing activity. But we also need to protect the critical habitats that these fisheries also depend on. Most species that are fished require more than one habitat to complete their lifecycles. For example Atlantic cod (Gadus morhua) spends its adult life shoaling in deep water, but juveniles require more stable habitat where they can hide such as seagrass meadows. So, if we want to manage stocks for sustainability, it is essential to protect the supporting habitats of targeted species. Seagrass meadows are a critical habitat supporting biodiversity and in turn the productivity of the world’s fisheries. Seagrass meadows are not only suitable for juvenile fish but also for larger fish of different species. As seagrass meadows occur in shallow, clear waters, they are an easily exploitable fishing habitat. Today, we published the first quantitative global evidence on the significant roles that seagrasses play in world fisheries . Seagrass as nursery grounds: provide a safer, less exposed, environment for eggs to be laid and young animals to find food and protection from predators as they grow. This includes commercial species such as tiger prawns, conch, Atlantic cod and white spotted spinefoot. In fact, one-fifth of the world’s most landed fish — including Atlantic Cod and Walleye Pollock benefit from the persistence of extensive seagrass meadows. Seagrass as a fishing area: it is not just large scale fishing industries that benefit from the presence of seagrass meadows. They are an easily accessible fishing ground used by small scale artisanal and subsistence fisheries around the world. Seagrass gleaning: seagrass is also essential habitat for gleaning activity, fishing for invertebrates such as sea cucumbers in water that is shallow enough to walk in. This is often done by women and children, and provides a source of essential protein and income for some of the most vulnerable people in tropical coastal communities. It is a common and increasingly visible activity, but it is not usually included in fishery statistics and rarely considered in resource management strategies. Seagrass supports other fisheries: seagrass also provides trophic support to other fisheries. They do this by creating expansive areas rich in fauna, from which there are vast quantities of living material, organic matter and associated animal biomass that supports other fisheries. Seagrasses also promote the health of connected habitats (like coral reefs), and have the capacity to support whole food webs in deep sea fisheries. Threats to seagrass, fisheries and food security: the coastal distribution of seagrass means that it is vulnerable to a multitude of land and sea derived threats. These include land runoff, coastal development, boating activity and trawling. On a global scale, seagrass is rapidly declining and when seagrass is lost associated fisheries and their stocks are likely to become compromised with profound and negative economic consequences. Seagrass meadows support global fisheries production Pdf Supporting policy and action is needed now! The importance of seagrass meadows for fisheries productivity and hence food security is not reflected by the policies currently in place. Urgent action is needed if we want to continue enjoying the benefits that healthy and productive seagrass meadows provide. Fisheries management must be broadened from just targeting fishing activity to also targeting the habitats on which fisheries depend. Awareness of the role of seagrass in global fisheries production, and associated food security, must be central to policy, and major manageable threats to seagrass, such as declining water quality, must be dealt with. Action is urgently needed to protect the worlds seagrass meadows if we are to continue to enjoy the benefits they provide.
Waste Not, Want Not. Discards that could feed those in poverty
At least 7.3m tons of fish (usually dead or dying) are thought to be discarded each year from marine fisheries around the world. But these estimates come mostly from observations of large-scale industrial fisheries. Limited attention has been paid to small-scale fisheries, which are assumed to have low discard rates – some estimate as little as 3.7% total catch, compared to more than 60% for some large-scale shrimp trawlers. Small-scale or artisanal fisheries – for which there is no universal definition – are generally considered more sustainable than their large-scale industrial counterparts, but there is increasing evidence that shows this is not always the case. They employ more than 99% of the world’s 51m fishers and likely account for more than half of the total global fisheries catches. A Sri Lankan fisherman. One of the biggest problems for both large and small-scale fisheries around the globe is bycatch – fish and other marine organisms caught when the fishers are targeting something else. Powerful images of turtles and dolphins caught in fishing gear have caught the sympathy of the general public, but unintentional landings of fish aren’t as evocative. The truth is, however, that fish bycatch is a big issue. Progress is being made in Europe within large-scale fisheries thanks to campaigns such as the Fish Fight. But small-scale fisheries – though there is increasing recognition outside that they are “too big to ignore” – are only just beginning to recognise the fish bycatch and discard problem. Catch and bycatch. Our newly published research has found that artisanal fisheries in Sri Lanka are throwing away more marine species than they keep. For every fishing trip in one of Sri Lanka’s largest lagoons, Puttalam Lagoon, fishermen could be throwing away more than 50 fish. What’s more, of the 62 species recorded in the survey, more than 80% were routinely discarded. The reasons for this practice are unclear but sometimes it is because the individual fish are too small – or they are species without a high market value. We found that fishers targeting shrimp in particular caught more non-target species and had higher discards than those targeting fish. This is particularly worrying at a time when Sri Lankan shrimp exports are increasing, after the EU granted the country improved access to its market. Fishers in Puttalam Lagoon discard non-target catch onshore. Potentially 90% of the world’s fish stocks are threatened by over-fishing – when more fish are caught than the population can replace. And the “tell-tale” signs of over-fishing are now being observed in Sri Lanka and across other research sites in the Indo-Pacific region. Fishers in these locations have told us and other researchers that they are catching much less fish than they were five years ago. But this is not just an ecological issue, it is a social one too. In this era of increasing food insecurity, our findings highlight a serious concern for Sri Lanka. This unwanted seafood could be used to provide protein for the poorest in society. Instead, we found that fish with high nutritional value is being eaten by feral dogs and birds. Unwanted fish end up as quick and easy meals for animals. Billions of people worldwide rely daily on fish for protein, while 50m people also rely on catching fish for work. But, if the levels of bycatch and discard continue, the livelihoods and food security of the people that depend on these fisheries will be under threat. If the problem is not managed, there won’t be any fish left in the waters. There is one ray of hope for Sri Lanka, however. There are some small-scale fishery cooperatives which maximise long-term community benefits by dealing with the threats of fisheries mismanagement, livelihood insecurity and poverty. Communities with successful and inclusive cooperatives are better off than those without. Cooperatives have the potential to empower small-scale fishers against environmental and socioeconomic shocks, but the problem in Puttalam Lagoon is that these cooperatives are not operating across all levels of society. Fishing cooperatives do exist, but there could be more. If the bycatch and discards issue is going to be solved over the long-term, we need to look at combining sustainable management practices with community schemes to reduce unnecessary seafood waste all over the world. Together the millions of small-scale fishers all over the world have an immense amount of power, they just need to realise it. This article was originally published on The Conversation. Read the original article.
Seagrass meadows key fishing ground globally
Fishing in seagrass occurs around the globe; if there is seagrass (and people) there is fishing. Still, the nature and extent of fisheries in seagrass is poorly understood. It is a prerequisite for natural resource management to understand resource exploitation, therefore we decided to investigate this further. Seagrasses are plants that grow in the shallow ocean. The seagrass attracts many different types of animals, to live, forage, or seek shelter. These animals are collected by humans for subsistence (food), commercial and recreational purposes. Across the globe the reasons for fishing differs, it is more common to fish for recreational purposes in countries where the economic situation is better, while in countries with more challenged economies fishing for subsistence is very important. Interestingly, because seagrasses grow in nearshore environments, almost all types of fishing gears are used. Close to shore in many areas of the world the seagrass gets exposed during spring low tides making it possible to walk in the seagrass meadows. Many people take advantage of the low tide and walk across the seagrass meadows collecting invertebrates, such as mussels and sea cucumbers, often with bare hand or simple fishing gear like sticks. This type of fishery is commonly referred to as gleaning or invertebrate harvesting and is conducted by men, women and children. Gleaning is especially common and important for people with limited resources. Static nets are also used in the intertidal zone, the area where the tides raise and fall, catching fish when the tides come in. It is very common to use hook and line and fishing nets in seagrass. Unfortunately, very destructive fishing gears such as bottom trawls, poison, dynamite, and rakes are also occasionally used. Women and children walk across seagrass meadows at low tide in indonesia collecting resources that they can eat (Photo: Benjamin Jones) On a global scale, anything found in the seagrass that can be eaten, sold, used as bait or sold as a curio is targeted. Globally, the most commonly targeted invertebrates in seagrass appear to be crabs and bivalves (mussels). The most commonly exploited finfish from seagrass are mullet, herring, and snapper. The target species varies greatly across the globe, for example in areas with high biodiversity (many types of species), the number of target species is often higher than in areas with low biodiversity. This pattern often corresponds with colder water fewer species, warmer water more species. Species groups that are least commonly targeted are sea cucumbers, small fish for drying, aquarium trade species, seahorses, and sharks. People access the seagrass fishing grounds by walking, swimming, snorkelling, free diving, use of canoes, scuba diving, use of sailboats and motorboats. Crabs and bivalves appear to be the most commonly targeted invertebrates across the globe (Photo: Benjamin Jones) Seagrass meadows receive limited management attention compared to other nearshore marine habitats. Fisheries management does not yet target seagrass. But seagrass fisheries are diverse and important to people the world over. We, authors, hope that these findings, now systematically and scientifically investigated, will highlight the importance of seagrass for fisheries around the globe. Source: ‘Global significance of seagrass fishery activity’ by Lina Mtwana Nordlund, Richard K.F. Unsworth, Martin Gullström, Leanne C. Cullen-Unsworth. Published in Fish & Fisheries 2017. Arial footage of a nearshore environment with patchy seagrass, in the upper left corner there is a fishing boat and along the right edge there is a long fishing net deployed (blue in color), Tanzania. Drone pilot and photo LM Nordlund.