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.
Puttalam Lagoon – Paradise Lost?
At the end of August I spent 10 days conducting fieldwork in Pattalam Lagoon, which is situated in the north west of Sri Lanka. The purpose of my visit to Puttalam Lagoon was to set up socio-economic and fish landings surveys with a research collaborator, who will now complete the surveys. This research was undertaken to contribute to a growing database covering South East Asia and beyond, linking seagrass meadows and food security, by using Sri Lanka as a case study. The lagoon was fringed with seagrass meadows and populated by many dense mangrove islands. Before the trip, I had profiled the area to gain some understanding of the people, the environment and the lagoon itself – which was once a tropical paradise. However, upon arrival I was faced with shock at the sheer size of the lagoon, measuring 327 km2, which was once surrounded by dense mangrove forests. From the onset it was clear that much of the once rich mangrove forests had been removed to make way for coconut plantations, salt production, rice cultivation and most notably shrimp farms – an industry that would be dominant throughout my findings. For the duration of my trip I was based in Kalpitiya, a relatively small, but densely packed town with a population just shy of 65,000. A large proportion of the population are refugees, whom fled Mannar in 1990’s when Tamil Tiger militants ordered them to leave or face death, and although they have lived in the area for over 20 years, many still desire to return home. Early starts. 5:30am at Oththakanna, the smaller of the two landing sites. Due to the nature of the research, which was split between landing surveys and household interviews, I was fortunate enough to spend much of my time with the large and lively fishing community where I focused on two very different landing sites. My day’s started early, meeting the fishermen at around 5:30am, just as they were returning to the landing site after collecting their catch. The first, more traditional landing site, where fishers mainly targeted shrimp, was made up of around 60 fishers and a small, coconut leaf hut, known locally as a Wardiya, was the focal point of the site and was used to weigh and sell shrimp. The second landing site was larger, fish were always the target species and had a strong community sense with a large number of older fishers helping to sort individual catches, which on some days were in excess of 400Kg. Upali ran his Wardiya very strictly, and all sales were weighed and recorded. At the smaller landing site, Oththakanna, it was clear that seagrass played an extremely important role in the fishery – “We catch more shrimp in seagrass” said Upali, the owner of the Wardiya, “Without seagrass, I would not be here”. Even though this was the case and all fishing occurred in seagrass there, the very nature of the seagrass shrimp fishery will be its downfall, with high levels of illegal fishing, most of which is damaging the seagrass. It was clear that fishing was primarily a source of income and not food, with extremely high and unregulated by-catch and fisher’s targeting shrimp only. Any shrimp that were caught were sold to a middleman whom would drive from up from Colombo, load up his ice filled truck, and then return to Colombo to prepare the shrimp for export. In some cases, over half the catch was discarded and numerous juvenile fish, including groupers, snappers and emperors, all highly valued sources of food at other case study locations, were either thrown to dogs and crows, or left on the beach. Of the by-catch species, seahorse are the only highly valued species, which can be sold to tourists for a high price. Yet the level of appreciation for seagrass, and the fishers desire to halt the use of illegal fishing gears gives some hope for the future. Catfish caught in the lagoon were mainly salted and dried – a cheaper source of protein than fresh fish. The larger landing site, Wannimundalama, was completely different with traditional non-motorised boats being replaced with more modern fibre glassed boats with outboard engines. The fishing was different too, and shrimp were no longer the target. Instead, net fishers targeted sardine, and in the majority of cases, this was all they caught. In some cases, catfish were also caught, but instead of being sold fresh, these were salted and dried. The fishing at this site was effective and a real community effort, with the men conducting the fishing, and women de-scaling and gutting the fish as soon as it was landed. Still, seagrass was appreciated for its value as a nursery area, and again fishers knew that if it was lost, they would no longer be able to fish. Although the data only displays a snapshot of the lagoon fishery, it is hoped that with continued research we can gain a deeper understanding of its complexity and begin to work with the fishers to minimise the impact their fishing is having on the seagrass meadows there. It wasn’t all doom and gloom, and I left hopeful as the fishers welcomed me into their “fishing family” and began to make an effort to return any live by catch to the sea – much to the dog’s disappointment. View more photos from Ben’s trip here.