New Standards for Reliable Fisheries: Preserving Population Diversity Stabilizes Fisheries, Ecosystems, and Economies

The many populations of sockeye salmon in Bristol Bay, Alaska act like a diversified portfolio of investments, buffering fisheries and incomes from the ups and downs of particular stocks. Sockeye salmon are one of the most valuable fisheries in the U.S., and since 1950, more than 60% of that value has come from Bristol Bay.

A new study in the June 3 issue of Nature quantifies, for the first time, just how much depends on this "portfolio effect." Without its current population diversity, the Bristol Bay sockeye fishery would close ten times more frequently -- once every two to three years rather than once every 25 years.
The study, by scientists at the University of Washington, draws on five decades of data and provides the first solid evidence that population diversity within a species plays a key role in maintaining stable fisheries.
"We believe this new evidence is a game-changer for managing species and entire ecosystems," says lead author Daniel Schindler, an ecologist at the University of Washington. "Population diversity of species is often overlooked by managers and conservationists. Yet in general, current rates of population loss are probably a thousand times higher than species loss."
The authors argue that, in order to maintain the steady flow of fish and other ecosystem services people depend upon, managers will need to put an explicit priority on preserving population diversity within species. Such strategies require aggressive protection of the habitat networks that ultimately generate and maintain population diversity. Both approaches will become increasingly important as a first line of defense against climate change.
"Part of it is understanding history and having the discipline not to chase the hottest stock of the day," says co-author Ray Hilborn, also at the University of Washington. "We have to maintain a range of productive elements -- a broad range of stocks."
With a landed value of more than $120 million in 2009, the Bristol Bay sockeye fishery has provided a reliable source of income and food year after year. This is because sockeye salmon are finely tuned to the individual streams and lakes in which they were born, and are thus incredibly diverse. Some populations do better in cold, wet years -- others thrive when it's hot or dry. Each population experiences its own boom and bust cycles based on environmental conditions and pure chance. But given sufficient diversity, there should be enough winners to make up for the losers every year for the species overall.
"Mother Nature does a pretty good job dealing with uncertainties -- climate change, for instance -- by producing a diversity of populations," explains Schindler. "In terms of fisheries, we need to have a longer- term vision for the viability of populations; the populations that are strong now are not necessarily going to be strong in coming years, so we need to protect weaker populations too, as insurance for the future."
Protecting weaker populations is a challenge- not only in salmon, but also in other species like tuna and cod. Managers must reduce fishing pressure below the levels that the stronger populations can tolerate, or distribute fishing pressure to protect diversity within stocks. The authors argue that in addition to protecting existing population diversity, we must also preserve and protect the variety of habitats that generate population diversity in the first place.
Many salmon rivers, including the Sacramento River in California and the Columbia in Washington, once enjoyed a high degree of population diversity and productivity. However, decades of heavy fishing, habitat degradation and reliance on hatcheries have dramatically simplified populations in these rivers. This has resulted in intense boom-and-bust cycles and frequent fishery closures. In British Columbia, major salmon rivers like the Skeena and Fraser have some populations that are highly depressed and show symptoms of decreased portfolio performance and increased vulnerability.
Hatcheries are frequently used to bolster wild salmon populations. But over time, hatchery fish can become closely related to one another, and can contribute to declines in unique wild populations. Eventually, hatchery-dominated areas can resemble one giant population. Just as intensive monoculture practices make food crops more vulnerable to disease or bad weather, a dependence on hatcheries can leave a fishery open to huge swings in fortune.
"The first lesson [of this paper] is that a wild multi-stock fishery can function very well on its own -- better than we've ever done with any kind of hatcheries," says Jack Stanford, an ecosystem scientist at the University of Montana who was not involved with the research. "Hatcheries are counterproductive if the goal is to sustain very healthy wild fisheries, especially in light of climate change."
Beyond hatcheries, the study results hold other important implications for wildlife management strategies in the US and beyond. In terms of habitat protection, for example, California is currently working on lessening the blow to Chinook salmon, delta smelt, Central Valley steelhead, and green sturgeon in the Sacramento and San Joaquin delta. A March 2010 report by the National Research Council supported recommendations by the Fish and Wildlife Service and the National Marine Fisheries Service to reduce the number of engineered diversions, such as dams and water diversion channels, in these river systems, on the grounds that they have negative consequences for these endangered species.
"In the Sacramento River, we have a history of exploitation and degradation going back to the gold rush," says Steve Lindley, a research ecologist with the National Marine Fisheries Service in Santa Cruz, CA, who was not involved with the research. "It's radically simplified the habitats that salmon depend on in the valley. In California, people have managed ecosystems with concrete. We build dams, line channels, and build flood control structures. Rivers need room to work, and they make salmon habitat if you let them. This research shows that sustainability depends on a healthy ecosystem, but our technological fixes to ecosystem problems usually have unintended consequences that make matters worse for salmon."
Salmon population loss is not confined to places with lots of people. The same activities that started eroding salmon diversity in the Columbia and Sacramento rivers a hundred years ago are spreading northward quickly.
"Bristol Bay, the most productive salmon ecosystem in the world, is facing decisions about major development proposals such as the giant Pebble Mine copper and gold mining facility, as well as hydroelectric dams," explains Stanford. "This research shows that the choices made in Bristol Bay today will help determine whether the fishery remains reliable for the next hundred years and beyond."
Hilborn adds, "Offshore drilling has also been proposed in Bristol Bay, and a spill similar to what we're seeing in the Gulf of Mexico could devastate this productive fishery. However the diversity in timing of migration to the ocean and age at maturation among different sockeye populations -- that is, the portfolio effect -- could afford them protection. In essence, protecting diversity is a form of insurance against the unexpected."
The lessons from Bristol Bay will be important for communities that rely on sustainable ecosystems, as well as the decision makers charged with managing them.
"This is a ground-breaking piece of work," says Jeff Hutchings, a professor of biology at Dalhousie University in Canada and former chair of the Committee on the Status of Endangered Wildlife in Canada, who was not involved with the study. "It's the strongest evidence to date that there's a financial benefit to maintaining population diversity -- and a greater chance that species can withstand environmental and human induced change. It's not done in a lab or in a tank. These are real rivers and a strong data set for a major fishery. If managers ignore this, they do so at their own peril."

Daniel E. Schindler, Ray Hilborn, Brandon Chasco, Christopher P. Boatright, Thomas P. Quinn, Lauren A. Rogers, Michael S. Webster. Population diversity and the portfolio effect in an exploited species. Nature, 2010; 465 (7298): 609 DOI: 10.1038/nature09060

Fishery Management Practices for Beluga Sturgeon Must Change, Experts Urge

A first-of-its-kind study of a Caspian Sea beluga sturgeon (Huso huso) fishery demonstrates current harvest rates are four to five times higher than those that would sustain population abundance. The study's results, which will be published in an upcoming issue of the journal Conservation Biology, suggest that conservation strategies for beluga sturgeon should focus on reducing the overfishing of adults rather than heavily relying upon hatchery supplementation.

The quantitative analysis was conducted through an unprecedented collaboration of scientists from the United States and Kazakhstan. Data used in the study were collected in the Ural River, the only remaining Caspian Sea river where beluga sturgeon reproduce unhindered by dams.
"This is the first time that anyone has calculated sustainable harvest limits for Caspian Sea beluga sturgeon and compared them to present fishing pressure," said Dr. Phaedra Doukakis, Senior Research Scientist with the Institute for Ocean Conservation Science at Stony Brook University and lead author of the study. "We can finally attach numbers to what people have suspected -- that current management of Caspian Sea sturgeon fisheries will not prevent further population decline. We hope that this study provides the evidence needed to shift mindsets and management practices," added Dr. Doukakis.
Populations of beluga sturgeon have declined by nearly 90 percent in the past several decades due to the high demand for black caviar, inadequate management, and habitat degradation.
Black caviar, the unfertilized roe (eggs) of the beluga sturgeon, is the most valuable of all caviar, and can be sold for as much as $8,000 for one kilogram (2.2 pounds). There has been grave concern about increasingly dwindling numbers of this already depleted species, which has gone extinct in the Adriatic Sea and is on the brink of extinction in the Azov Sea.
The results of the analyses* conducted by the participating scientists show that fishing pressure far exceeds sustainable levels and that limiting the take of adult and subadult sturgeon will contribute more to the population growth rate as compared with hatchery supplementation.
The beluga sturgeon can live more than 100 years, and do not reach maturity until 9 to 20 years of age. The researchers found that the optimal age of first harvest is 31 years because older and larger fish produce more eggs. Conservation efforts would be much more effective than current practices if minimum size limits for fishing targeted this optimum age for first capture and if the illegal harvest of subadult fish were reduced. These fishing limits would allow the survival of subadult and adult females and would increase population productivity by ten times that achieved by hatchery supplementation, according to the study's findings.
Currently the fishery management focus for beluga sturgeon conservation is on using hatcheries to sustain the population. However, survival of hatchery-reared fish in the wild is thought to be very low. Additionally, genetic diversity may be compromised by hatchery practices, which can potentially jeopardize the long-term survival of all beluga sturgeon. Despite the potential threats posed by hatchery fish, regulatory agencies allow more fishing (higher quotas) by countries with higher hatchery output.
"This study clearly shows that reducing the mortality of wild beluga sturgeon adults is a much more effective conservation strategy than hatchery supplementation," said Dr. Ellen Pikitch, Executive Director of the Institute for Ocean Conservation Science and a co-author of the study. "Ten hatchery fish would need to be produced to achieve the same conservation benefit as preventing the kill of a single wild beluga sturgeon. It's clear that the focus of sturgeon management in the region has been misplaced and must change. A shift in practices could prevent further declines in beluga sturgeon and ultimately promote recovery," added Dr. Pikitch.
The Convention on International Trade in Endangered Species (CITES) listed beluga and most other species of sturgeon as threatened in 1998 with an Appendix II listing. However, beluga sturgeon numbers have declined by approximately sixty percent from the time of the listing through 2005 showing that existing management of beluga sturgeon fisheries has not been effective. The new research results suggest that a change in management focus is critical to stabilization and recovery of the species.
Drs. Pikitch and Doukakis will present the findings of this study and related research on the status of beluga sturgeon at a meeting they are convening on March 18, 2010 at the 15th Conference of Parties to CITES in Doha, Qatar.
*Scientists participating in the study used yield per recruit, spawning stock biomass per recruit, and elasticity analyses to make their evaluations. The first two analyses use life history parameters to determine acceptable levels of fishing mortality. The elasticity analysis uses similar parameters to pinpoint those parts of the fish's life history that contribute most to population growth. Doukakis et al. Management and Recovery Options for Ural River Beluga Sturgeon. Conservation Biology, 2010; DOI: 10.1111/j.1523-1739.2010.01458.x

Can marine reserves boost fish populations outside their borders?

A new study shows that higher fish reproduction inside marine reserves is likely to benefit fisheries outside, as ocean currents carry the tiny, young fish to surrounding waters.
However, the study also indicates that if the young, exported from marine reserves, disperse across large areas it may be extremely difficult to detect a boost to fisheries.
Robin Pelc and three collaborators used a new modeling approach to explore the potential impacts of marine protected areas on fish populations outside the reserve boundaries. The findings appear in a special edition of the Proceedings of the National Academy of Sciences that focuses on marine reserves.
Typically, marine reserves prohibit fishing, oil extraction, seabed mining, or other destructive and extractive human activities. In the last decade, these types of protected areas have become increasingly popular as a tool for ocean conservation and management.
Marine reserves are widely recognized as having many conservation benefits within their borders. Numerous studies have shown that population densities of fish and invertebrate species tend to be higher, biodiversity tends to be greater, and body sizes of fish and invertebrates tend to be bigger.
However, many fishermen oppose new preservation because they do not want to lose access to fishing grounds, and they believe that the same fishing effort will be squeezed into a smaller area outside the reserves.
So far, their opposition has not been swayed by the possibility that marine reserves might boost fisheries by "seeding" surrounding areas with planktonic offspring of fish and invertebrates that drift outside the boundaries. To date, empirical evidence to support this idea has been scant.
Pelc and her coauthors used a “simple idealized coastline model to estimate the expected magnitude and spatial scale of larval export from no-take marine across a range of reserve sizes and larval dispersal scales.” Most notably, they found that,
“Given the magnitude of increased production typically found in marine reserves, benefits from larval export are nearly always large enough to offset increased mortality outside marine reserves due to displaced fishing effort.”
However, the increase at any given point outside the marine reserves would be quite small, meaning it would be nearly impossible to see in field studies. So, while this new research clarifies that marine reserves could benefit fisheries, it also indicates that the positive impact may be extraordinarily difficult to detect.
Managers and conservationists therefore face a daunting scientific challenge if they need real-world data to convince fishermen that marine reserves can help sustain their livelihoods.
--Reviewed by Peter Taylor
Pelc, R., Warner, R., Gaines, S., & Paris, C. (2010). Marine Reserves Special Feature: Detecting larval export from marine reserves Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0907368107

Fish and fishermen: sustainable species?

Charter captains, bait shops and commercial fishing fleets from Key West to Puget Sound are losing jobs and money as sweeping restrictions on dozens of fish take effect nationwide, based on data that regulators know is inaccurate.For Walt's Fish Market in Sarasota, the closures mean the business will be forced to pay higher prices for grouper, a popular fish that local consumers demand. Regulators say they need to overhaul the science behind their decision-making, which relies partly on numbers collected through random phone calls to coastal homes. But they must err on the side of caution under 2007 laws setting a deadline for ending overfishing in the U.S. by Jan. 1, 2010.Thousands of recreational and commercial fishermen plan to protest outside the Capitol in Washington on Wednesday to push for lesser regulations until the science improves.The tougher regulations stem from rising concerns over the health of fish populations globally and the desire to manage fishing sustainably in the U.S."The good thing about sustainable fisheries is the fish should be easy to catch," said Steve Murawski, chief science adviser for NOAA fisheries. "The fishing should be excellent and people should not be using the opportunity to take what they can get, but taking what's appropriate."Science has lagged behind policy-making. Efforts to improve fisheries data began this year, four years after the National Academy of Sciences recommended a complete redesign and three decades after a key component of the current information-gathering system was devised."It's taking time to go from one system to the next and we're in transition," Murawski said. "We can't not regulate fisheries while we are trying to go through that transition."If the science overstates the problem, that is good for the fish, he said. If estimates are correct, or the situation is worse, lack of action could do significant long-term harm."If we're uncertain about the status, we should give the benefit of the doubt to the fish," Murawski said.But fishermen contend that the fish they are after -- grouper, red snapper, flounder and others -- are neither in danger of extinction nor at risk of a population collapse. They contend lives are being ruined on faulty assumptions."The best thing for the fishery is not just to slam it shut just because you don't know what's going on out there," said David Heil, a recreational fisherman from Winter Park who also serves as an attorney for the Recreational Fishing Alliance. "They're making some regulations that really are draconian in nature."The closures are putting charter captains, commercial fishermen, bait and tackle shops, boat repair shops and others out of business, Heil said.The effect is widespread throughout the east coast and more pronounced in Florida, where 40 percent of all recreational fishing nationwide takes place."The economy is in such a critical state to be making regulations based on flawed data, and regulations that affect the incomes of people that are already in a struggling economy, is wrong," said Al Rodriguez, tackle and bait specialist at Economy Tackle in Sarasota.A broad impactFor Walt's Fish Market in Sarasota, the closures mean higher prices for grouper, which the business will absorb, and reliance on other fish species.We have so many other great fish here," said Chip White, the market's general manager, listing mahi mahi and four kinds of snapper other than red snapper. The market demands grouper, however, and White will have to buy it from fishermen other than those who usually supply him. That is why he will have to pay a higher price.Similarly, restaurants here are importing grouper from Mexico or not offering it. At the Crab and Fin on St. Armands Circle, the menu lists cobia, Spanish mackeral and yellow-eyed snapper."Grouper and red snapper we're staying away from because of the ban," said Scott Mcdonald, restaurant manager. "There's so much demand for grouper and there's only so many legitimate sources for it."Despite recreational closures in the Gulf, commercial fishermen here can still catch grouper and red snapper, unlike on the state's east coast.The clamp-down stems from the 2007 reauthorization of the Magnuson-Stevens Fishery Conservation and Management Act. In addition to setting the deadline to end overfishing nationwide, the act required an overhaul of the way the fisheries service calculates fish populations, an expensive, time-consuming task.The fisheries service was recently given $5 million and a staffing boost of about 15 people to help fix the problems, Murawski said.But flaws have been known for at least a decade. The National Research Council brought attention to the problems in 2000.The National Academy of Sciences' follow-up in 2006 criticized recreational surveys, which were conducted in the field and over the phone.Until this year, surveyors estimated the catch by randomly calling households in coastal counties trying to contact recreational anglers. Anglers' catch reports were entered as scientific data, even if their last trip had been months prior.In the field, surveyors also visited piers and docks to interview anglers. No guidelines informed surveyors on how to collect data randomly. Instead, they tended to interview only those fishermen who had made landings, resulting in overestimates.Other variables, such as weather's effect on reducing catch, were not included, resulting in widely variable catch estimates from year to year.The surveys were developed in 1979 to gather basic information on recreational fishing, not to assess fish populations, according to the National Academy of Sciences.The recreational data are combined with more accurate commercial data and other information to determine the health of fish populations and to set commercial and recreational fishing restrictions.The information is imprecise, Murawski acknowledged, but still reflects fish population trends.Slow progressNew survey guidelines took effect this year. Driving many of the improvements was a recent national law requiring all anglers to register for a license. The license -- free in some states -- allows surveyors to call known anglers, not random households.Ocean conservation groups credit the fisheries service for improvements, but they, too, say it has been disappointingly slow.Chris Dorsett, director of fisheries conservation and management for Ocean Conservancy, said the biggest problems are the service's poor estimates on how many fish are caught and released dead, especially in the commercial sector.The fisheries service also needs to speed up recreational catch estimates to stop overharvests or to loosen unnecessary restrictions.Holly Binns, manager for the Pew Environment Group's campaign to end overfishing in the Southeast, said the key is not to "weaken protections that are in place right now."A lot of species are showing signs of recovery. We need more time to see it."

Sustainable Fisheries Needed for Global Food Security

Increased aid from developed countries, earmarked specifically for sustainable seafood infrastructure in developing countries, could improve global food security, according to a policy paper by an international working group of 20 economists, marine scientists and seafood experts in the Feb. 12 issue of Science.Seafood is a significant source of protein for nearly 3 billion people and is the planet's most highly traded food commodity, contributing to the livelihoods of more than 560 million people. But a lack of coordinated policy threatens global seafood supplies.To help safeguard future supply, "the price of seafood has to reflect the cost of maintaining ecosystem health in the countries that capture or farm most of it," says Martin D. Smith, lead author of the paper and associate professor of environmental economics at Duke University's Nicholas School of the Environment. "Many imports are coming from developing countries that are not necessarily well-positioned to manage their resources sustainably.""In an ideal world, each country governs its own resources well and the seafood trade contributes to worldwide economic growth and food security," Smith says. "But that's not the world we live in right now." Developing countries may produce more seafood than they can consume, exporting it and using the earnings to purchase other foods, goods or services.In their Science article, Smith and his co-authors examine the complex environmental, political and economic factors that jeopardize global seafood supplies and livelihoods."Issues of resource ownership and governance are at the top of the list," says Cathy A. Roheim of the University of Rhode Island. No one owns fish stocks or has sole control over what their catch limits should be, or what type of gear or practices can be used to catch them. This has pushed many stocks beyond maximum sustainable yields, and has led to the current precarious role of fisheries in food security.Concurrently, "aquaculture (farming seafood) has great promise for enhancing food security but is also threatened when regulations fail to protect the supporting ecosystems," says Smith.Smith, Roheim and their colleagues weigh the pros and cons of three policy options to sustain seafood production.Trade policies such as import bans and tariffs could be used to punish countries that fail to meet sustainability standards, "but these are rather blunt instruments," Smith says. "In the short run, you may end up hurting people who are the most vulnerable."Private incentives, such as ecolabeling, that raise the price of seafood to help pay for sustainable practices, are another option. But it's not clear from existing studies if enough consumers will voluntarily pay more for seafood. And raising the price of high-valued products such as shrimp or tuna, which are mostly exported to developed countries, could backfire. Consumers might then seek out less expensive alternatives that people in poor, developing countries depend on. This may raise prices of low-valued products and put products with high nutritional value out of reach of the poorest of the poor.A third option -- allocating more foreign aid for sustainable infrastructure in developing countries -- provides clear advantages, Smith believes. By specifically earmarking aid for things like sustainable fishing gear, improved management, sustainable aquaculture facilities, or systems to verify sustainability compliance, developed countries will foster food security and ecosystem health, and strengthen seafood trade, without causing short-term hardships to consumers or producers."We're not suggesting that foreign aid for sustainability should replace other aid that contributes to food security," Smith notes. "We're just saying this is an option that is often overlooked."The Duke-led working group is funded by the National Center for Ecological Analysis and Synthesis. Larry Crowder, director of the Nicholas School's Center for Marine Conservation, and Mary Turnipseed, a PhD student at the school, co-founded and co-direct the group with Smith.Other members come from National Center for Ecological Analysis and Synthesis; University of Rhode Island, University of California-Santa Barbara; University of Stavanger, Norway; Hawaii Institute of Marine Biology; University of Georgia; University of Arizona; Stanford University; World Wildlife Fund; Southwest Fisheries Science Center; Memorial University and Dalhousie University, Canada; Norwegian University of Life Sciences; Whole Foods Market; and Comunidad y Biodiversidad A.C., Mexico.

Fisheries and Aquaculture Face Multiple Risks from Climate Change

A new report, published by the Food and Agriculture Organization (FAO) of the United Nations, predicts "an ocean of change" for fishers and fish farmers. It concludes that urgent adaptation measures are required in response to opportunities and threats to food and livelihood provision due to climatic variations.

The study, 'Climate change implications for fisheries and aquaculture', is one of the most comprehensive surveys to date of existing scientific knowledge on the impacts of climate change on fisheries and aquaculture. Covering some 500 scientific papers, the picture the FAO review paints is one of an already-vulnerable sector facing widespread and often profound changes.

The report includes contributions from experts from around the world, including Dr Tim Daw and Prof Katrina Brown of the School of International Development and Prof Neil Adger of the School of Environmental Sciences at UEA. Other contributors come from the WorldFish Center, Globec, Network of Aquaculture Centres in Asia-Pacific, and Fisheries and Oceans Canada.

Dr Daw and Profs Adger and Brown co-authored the chapter 'Climate change and capture fisheries: potential impacts, adaptation and mitigation', which looks at the social vulnerability of fisherfolk to climate change. "Marine and freshwater ecosystems will be profoundly affected by processes like ocean acidification, coral bleaching and altered river flows with obvious impacts on fisherfolk, but it is not just about what happens to the fish," said Dr Daw. "Fishing communities are vulnerable to sea level rise and their livelihoods are threatened by storms and extreme weather. Meanwhile, the social and economic context of fisheries will be disrupted by impacts on security, migration, transport and markets."

"Fisheries are already rapidly evolving due to overexploitation and globalisation. They will suffer from wide range of different impacts from climate change, which may be unpredictable and surprising. The poorest will be least able to adapt to these impacts. For example in Kenya poorer fishers were shown to be less likely to switch to other livelihoods if catches declined."

Prof Adger added: "Climate change is going to be a huge challenge to every sector of society and what we're learning about fisheries shows how difficult adaptation will be, particularly for the poorest parts of the world."

According to the report, marine capture fisheries already facing multiple challenges due to overfishing, habitat loss and weak management are poorly positioned to cope with new problems stemming from climate change. Small island developing states -- which depend on fisheries and aquaculture for at least 50 percent of their animal protein intake -- are in a particularly vulnerable position.

Some 520 million people depend on fisheries and aquaculture as a source of protein and income. For 400 million of the poorest of these, fish provides half or more of their animal protein and dietary minerals. Many fishing and coastal communities already subsist in precarious and vulnerable conditions because of poverty and rural underdevelopment, with their wellbeing often undermined by over-exploitation of fishery resources and degraded ecosystems.

Inland fisheries -- 90 per cent of which are found in Africa and Asia -- are also at risk, threatening the food supply and livelihoods of some of the world's poorest populations. Warming in Africa and central Asia is expected to be above the global mean, and predictions suggest that by 2100 significant negative impacts will be felt across 25 per cent of Africa's inland aquatic ecosystems.

Fish farming will also be affected. Nearly 65 per cent of aquaculture is inland and concentrated mostly in the tropical and subtropical regions of Asia, often in the delta areas of major rivers at the mid- to upper levels of tidal ranges. Sea level rise over the next decades will increase upstream salinity, affecting fish farms.

A crucial issue highlighted by the report relates to how well such communities will be able to adapt to change. For example, even if African coastal fisheries do not face huge impacts, the region's 'adaptive capacity' to respond to climate change is low, rendering communities there highly vulnerable even to minor changes in climate and temperatureAdapted from materials provided by University of East Anglia.

Bangladesh to lose most marine fish

Bangladesh is poised to lose most of its marine fish populations as a result of climate change, dealing a big blow to thousands of people dependent on fishing in the sea, according to experts. "Bangladesh has a long coastal belt of 710 kilometers with abundant marine resources. We've so far found some 475 species of marine fishes, 400 of mollusc and 200 species of sea-woods. Unfortunately, some of them have disappeared and many more are on the verge of extinction," Prof Nani Gopal Das of Chittagong University's Marine Biology Department told UNB.The scientific names of some of the marine fishes of various countries, including Bangladesh, which have been included in the Red List of the International Union for Conservation of Nature (IUCN) are Johnius coitor, Nematalosa galatheae, Pseudapocryptes elongates, Thunnus albacares, Thunnus obesus and Xiphias gladius. Prof Nani Gopal said monsoon variations, frequent droughts and severe storms will also kill the fish in inland freshwater bodies and affect their breeding patterns. "When there will be a significant effect on the ecosystems, this would also endanger a vital food source in some coastal areas."He added: "Several fishes as we mentioned will be eliminated from these areas if they cannot quickly adapt to the changing salinity levels. Fishes are very sensitive to temperature too and some species those that can't swim very far - may go locally extinct." Nani Gopal pointed out a number of rea sons behind the ecological degradation of the Bay of Bengal. These include increase in sea temperature due to global warming; increase in salinity due to environmental pollution, habitat conversion of the marine fishes; massive resource consumption by the growing population; introduction of exotic species; and commercial exploitation or over-hunting. According to an international study conducted by WorldFish with support from the UK's Department for International Development (DFID), both coastal and landlocked countries in Africa, including Malawi, Guinea, Senegal and Uganda, four Asian tropical countries - Bangladesh, Cambodia, Pakistan and Yemen - and two countries in South America, Peru and Colombia, are the most economically vulnerable to the effects of global warming on fisheries. Overall, of the 33 countries that were considered highly vulnerable, 19 are already classified by the United Nations as "least developed" due to their particularly poor socioeconomic conditions. According to the United Nation's Food and Agriculture Organisation (FAO), fishes provide more than 2.6 billion people worldwide with at least 20 percent of their average annual per capita protein intake. The "highly vulnerable" countries identified in the WorldFish study produce 20 percent of the world's fish exports (by value). The researchers note that these countries should be on a priority list for adaptation efforts that will allow them to endure the effects of climate change and maintain or enhance the contributions that fisheries can make to poverty reduction.Worried at the rapid climate change, Prof Nani Gopal said the impact of climate change on fisheries and aquaculture is already being felt. In marine waters, extreme weather events will increase in frequency and intensity - the most well known of these is the El Niño phenomenon in the South Pacific.AFM Shahidur Rahman, an environmentalist, said the ongoing warming of the world's oceans is likely to continue, but with geographical differences and some decadal variability. Warming is more intense in surface waters but is not exclusive to these with the Atlantic showing particularly clear signs of deep warming.He said changes in fish distributions in response to climate variations have already been observed, generally involving pole ward expansions of warmer-water species and pole ward contractions of colder-water species.Prof Nani Gopal said shifts in ocean salinity are occurring, with near-surface waters in the more evaporative regions of most of the world's oceans increasing in salinity, while marine areas in high latitudes are showing decreasing salinity due to greater precipitation, higher runoff, melting ice and other atmospheric processes. And the oceans are becoming more acidic, with probable negative consequences to many coral reef and calcium-bearing organisms.He put forward three recommendations - developing a proper management policy, conservation of biodiversity through pollution control and maintenance of the breeding ground - to protect the endangered marine fish populations. "The 200 species of sea-woods growing around the St Martin's Island are the main food of the marine fishes," he said underscoring the need for protection of these planktons as these creature play a vital role in maintaining the ecological balance of the sea.