Production Fish Need a Tranquil Start to Avoid Malformation

For production fish, a serene start to life raises their chances for normal development. This is the main conclusion of a major research project on malformations in cod and salmon.

Funded by the Research Council of Norway through the AQUACULTURE programme, five Norwegian research institutions have worked together to expand the overall understanding of an issue of great concern within the aquaculture industry: malformations. "We now know more than anyone in the world about malformations in production fish," asserts Grete Baeverfjord, Senior Research Scientist at Nofima Marin.
Dr Baeverfjord headed a collaborative project between Nofima Marin, Nofima Mat, the Institute of Marine Research, the National Institute of Nutrition and Seafood Research (NIFES) and the University of Bergen.
Malformed cod
This winter, Norwegian fishermen have caught quite a few malformed cod -- which are in all likelihood escaped production cod. Both the quality of fry and malformations in adult cod pose major challenges for the aquaculture industry.
"Our research indicates that cod would benefit significantly from a lower-temperature environment during first-feeding," says Dr Baeverfjord. The same findings apply to salmon. Researchers believe that maintaining low water temperature during the early development phases is the most important preventive measure fish farmers can implement for both species.
However, in other areas cod and salmon show differences. "Cod must not be subjected to too strong a current in the tank. We recommend slowing down the current to prevent spinal column fractures. This is the second-most important measure for avoiding malformations in cod. For salmon, improper feed is the number two cause of abnormalities."
"Our conclusion is that both cod and salmon should be given a more peaceful start to life than they get now," states Dr Baeverfjord, advising producers not to stress their fish too much during the fry stage.
Dr Baeverfjord is confident that the Norwegian aquaculture industry will follow researchers' advice, as this will pay off financially in the long run. "We see that the major salmon-farming companies have already implemented our recommendations, which has helped to spur the growth of the salmon industry in recent years."
In a collaborative effort with scientists in other European countries, Norwegian researchers have established the web portal www.finefish.info. The website provides concrete advice to aquaculture producers on how to prevent malformations, as well as recommendations for protocols and more. The project has also resulted in a manual entitled "Control of malformations in fish aquaculture: Science and practice," which may be ordered or downloaded on the website.

The Research Council of Norway (2010, May 5). Production fish need a tranquil start to avoid malformation. ScienceDaily. Retrieved May 6, 2010, from http://www.sciencedaily.com­ /releases/2010/04/100430082014.htm

Half Of Fish Consumed Globally Is Now Raised On Farms, Study Finds

Aquaculture, once a fledgling industry, now accounts for 50 percent of the fish consumed globally, according to a new report by an international team of researchers. And while the industry is more efficient than ever, it is also putting a significant strain on marine resources by consuming large amounts of feed made from wild fish harvested from the sea, the authors conclude. Their findings are published in the Sept. 7 online edition of the Proceedings of the National Academy of Sciences (PNAS).

"Aquaculture is set to reach a landmark in 2009, supplying half of the total fish and shellfish for human consumption," the authors wrote. Between 1995 and 2007, global production of farmed fish nearly tripled in volume, in part because of rising consumer demand for long-chain omega-3 fatty acids. Oily fish, such as salmon, are a major source of these omega-3s, which are effective in reducing the risk of cardiovascular disease, according to the National Institutes of Health.
"The huge expansion is being driven by demand," said lead author Rosamond L. Naylor, a professor of environmental Earth system science at Stanford University and director of the Stanford Program on Food Security and the Environment. "As long as we are a health-conscious population trying to get our most healthy oils from fish, we are going to be demanding more of aquaculture and putting a lot of pressure on marine fisheries to meet that need."
Fishmeal and fish oil
To maximize growth and enhance flavor, aquaculture farms use large quantities of fishmeal and fish oil made from less valuable wild-caught species, including anchoveta and sardine. "With the production of farmed fish eclipsing that of wild fish, another major transition is also underway: Aquaculture's share of global fishmeal and fish oil consumption more than doubled over the past decade to 68 percent and 88 percent, respectively," the authors wrote.
In 2006, aquaculture production was 51.7 million metric tons, and about 20 million metric tons of wild fish were harvested for the production of fishmeal. "It can take up to 5 pounds of wild fish to produce 1 pound of salmon, and we eat a lot of salmon," said Naylor, the William Wrigley Senior Fellow at Stanford's Woods Institute for the Environment and Freeman Spogli Institute for International Studies.
One way to make salmon farming more environmentally sustainable is to simply lower the amount of fish oil in the salmon's diet. According to the authors, a mere 4 percent reduction in fish oil would significantly reduce the amount of wild fish needed to produce 1 pound of salmon from 5 pounds to just 3.9 pounds. In contrast, reducing fishmeal use by 4 percent would have very little environmental impact, they said.
"Reducing the amount of fish oil in the salmon's diet definitely gets you a lot more bang for the buck than reducing the amount of fishmeal," Naylor said. "Our thirst for long-chain omega-3 oils will continue to put a lot of strain on marine ecosystems, unless we develop commercially viable alternatives soon."
Naylor and her co-authors pointed to several fish-feed substitutes currently being investigated, including protein made from grain and livestock byproducts, and long-chain omega-3 oils extracted from single-cell microorganisms and genetically modified land plants. "With appropriate economic and regulatory incentives, the transition toward alternative feedstuffs could accelerate, paving the way for a consensus that aquaculture is aiding the ocean, not depleting it," the authors wrote.
Vegetarian fish
Fishmeal and fish oil are important staples at farms that produce carnivorous fish, including salmon, trout and tuna. But vegetarian species, such as Chinese carp and tilapia, can be raised on feed made from plants instead of wild-caught fish. That's one reason why farm-raised vegetarian fish have long been considered environmentally friendly.
In the early 1990s, vegetarian fish farms began adding small amounts of fishmeal in their feed to increase yields. However, between 1995 and 2007, farmers actually reduced the share of fishmeal in carp diets by 50 percent and in tilapia diets by nearly two-thirds, according to the PNAS report. Nevertheless, in 2007, tilapia and carp farms together consumed more than 12 million metric tons of fishmeal—more than 1.5 times the amount used by shrimp and salmon farms combined.
"Our assumption about farmed tilapia and carp being environmentally friendly turns out to be wrong in aggregate, because the sheer volume is driving up the demand," Naylor said. "Even the small amounts of fishmeal used to raise vegetarian fish add up to a lot on a global scale." Removing fishmeal from the diet of tilapia and carp would have a very positive impact on the marine environment, she added.
Regulating fisheries
On the policy front, Naylor pointed to California's Sustainable Oceans Act and the proposed National Offshore Aquaculture Act, which call for reductions in the use of fishmeal and fish oil in feeds. She also applauded plans by the National Oceanographic and Atmospheric Administration to develop a comprehensive national policy that addresses fisheries management issues posed by aquaculture. "No matter how much is done from the demand side, it is essential that there be regulation on the supply side as well," Naylor said. "You won't prevent the collapse of anchoveta, sardine and other wild fisheries unless those fisheries are carefully regulated."
Other co-authors of the PNAS study are Ronald W. Hardy, University of Idaho; Dominique P. Bureau and Katheline Hua, University of Guelph (Canada); Alice Chiu, Stanford; Matthew Elliott, Sea Change Management; Anthony P. Farrell, and Ian Forster, Centre for Aquaculture and Environmental Research (Canada); Delbert M. Gatlin, Texas A&M University and the Norwegian Center of Excellence; Rebecca J. Goldburg, Pew Charitable Trusts; and Peter D. Nichols, Commonwealth Scientific and Industrial Research Organization (Australia).
The PNAS report was supported by the David and Lucile Packard Foundation.
Adapted from materials provided by Stanford University, via EurekAlert!, a service of AAAS.

Norway fish farms thrive under ecologists' watchful eye

Tucked away in the corner of an enchanting fjord, 600,000 baby trout frolick in underwater cages as they wait their turn to end up on dinner plates: fish farming is booming in Norway, under the watchful eye of environmentalists.In Oeygarden near the western Norwegian town of Bergen, the Blom family's fish farm consists of a building constructed on the water and three submerged basins where the fish are raised.It is just one of the 800 fish farms dotting the coastline in the Scandinavian country, where three times more salmon and trout are produced than meat.But while fish farming helps ease the pressure that industrial fishing is putting on the planet's fish stocks, it is not without its own slew of problems.Farmed fish that escape, rampant illnesses and a debate over feed have tarnished the reputation of a sector whose exports totalled 2.5 billion euros (3.5 billion dollars) in Norway last year."In some areas the problems are so big that we cannot certify that it is (environmentally) sustainable. We should chill down the growth and make sure that all the main problems are under control," says Geir Lasse Taranger, research program manager at Bergen's Institute of Marine Research.Heavy concentrations of fish encourage the spread of diseases and parasites that can have a disastrous effect on stocks, such as Lepeophtheirus salmonis, a louse that attacks fishes' skin and mucous membranes.In Chile, the second-biggest producer of farmed salmon after Norway, a virus that emerged earlier this year devastated stocks and halved production, putting 20,000 people out of work, according to the international environmental group Pure Salmon Campaign.The problems are not limited to the fish farms. Many of the farmed fish escape from their cages and contaminate the wild salmon, thereby weakening the stocks' genetic makeup."The wild genotype will disappear if there are too many escapes," Taranger said.Fish farms saw a peak of 920,000 salmon escapes in 2006, prompting the industry to roll up its sleeves and tackle the problem.Divers who inspect the cages' nets as well as video cameras helped bring the number of escapes down to just 100,000 last year.The industry's woes haven't ended with that, though. Fish farmers feeding practices have also landed them in the hot seat.A recent Swedish documentary created a stir in Scandinavia when it accused Norwegian fish farms of emptying the oceans. In order to produce one kilogramme (2.2 pounds) of farmed fish, the equivalent of 2.5 kilogrammes of wild fish in meal and oil are needed.Norway's farms, which produced just over 800,000 tonnes of fish last year, consumed 2.0 million tonnes of wild fish.But professionals say their practices are among the best in the food industry."Salmon and trout are very efficient in the use of proteins, much more so than chicken, pork or beef" which require more feed per kilogramme produced, insists Oeyvind Blom, who runs the family farm in Oeygarden."So it's very sustainable and environmentally friendly in our view," he says. But environmentalists, who are generally favourable to fish farming, still want to see an improvement. "We're not concerned about the ratio between the quantity of feed and the final product. What worries us is what the feed is made of," says Nina Jensen, a marine biologist at World Wide Fund for Nature (WWF) Norway. She says some of the fish meal and oil are derived from wild fish stocks that are vulnerable, such as sand eel, Icelandic mackerel and Norway pout. The WWF has therefore called for the feed contents to be traceable so that producers know which fish were used in the process. "We know it for any other farmed animal, so why not farmed fish," asks Jensen.

How Baby Fish Find A Home

One of the most significant questions facing marine ecologists today, is just how much of an impact global variations in the environment are having on the dispersal of larval and juvenile marine species from open oceans to coral reefs। Previously, tracking how fish larvae migrate was done through direct observation by divers on older larvae found near the reefs, after they'd spent weeks to months in the plankton. This method did not permit divers to follow small larvae, diving larvae or larvae as they returned to the reefs at night. How tiny coral reef fish larvae locate the reef habitat across vast expanses of water has remained an enduring mystery.

An innovative research tool, designed by UM Rosenstiel School of Marine and Atmospheric Science, division of Applied Marine Physics Assistant Professor, Dr. Claire B. Paris and Senior Research Associate Cedric Guigand is making the task possible on younger larvae as they move with currents. Dubbed the OWNFOR (Orientation With No Frame Of Reference) system, this drifting observational device, which resembles a kite, allows researchers to observe marine larvae naturally influenced by factors in the open ocean. The floating chamber is designed to detect and quantify the orientation of larval coral reef fish in the pelagic environment; an often pitch black void with little or no frame of reference to navigate.
The OWNFOR system is deployed at sea and drifts while videotaping the movement of a larva placed within a clear, circular arena. It will also be possible to change their immediate environment and manipulate orientation cues, such as acoustic, chemical, or magnetic fields that larvae may use to navigate. This new system will be equipped with an infrared camera that can verify the larvae's orientation at night.
Through a research grant from The Hermon Slade Foundation and a fellowship from the Australian Museum, she will be putting her new larval monitoring system to the test in early 2008. Paris and colleagues are interested in gathering data on the successful identification of larval abilities to orientate as they mature.
"Typical research on larvae is assessed in laboratory experiments or in studies done in situ with the naked eye, but it does not provide information on whether or not larvae use cues to find a home, when in their life history they use them, or how far from the reef they can sense the cues। We're hoping to find out how the larvae behaviorally interact with the blue-water environment minimizing human intervention," said Paris. "The success of this new device in recording true orientation in fish larvae opens new possibilities for research in the field of larval ecology."

Working at the Lizard Island Research Station, a satellite-facility of the Australian Museum on the Great Barrier Reef, Paris will directly compare her research methods with those of Lizard Island researcher, Dr. J.M. Leis, who published his results diving and following larval fish. Researchers hope that OWNFOR will provide minimal interference in the natural migration of organisms, helping to understanding just what influences these organisms to settle on a final reef home after days or weeks in a relatively featureless open ocean landscape.
"The larval phase is often the main opportunity in benthic organisms to colonize new habitats, but how far from home are these new habitats? They can range from tens of kilometers away to the natal reef (reef of origin). Ideally, we'll discover crucial inputs for a new generation of biophysical larval dispersal models vital to achieving a better understanding of larval connectivity in marine systems," said Paris. "The implications will have global impacts on the effective management of fisheries, conservation of marine biodiversity, including design of marine reserves, and helping to predict the effects of climate change on marine systems."
Paris earned her master's degree in biology and living resources from the Rosenstiel School, and her Ph.D. in coastal oceanography from SUNY Stony Brook's Marine Sciences Research Center. Her current research is also funded by the National Science Foundation's division of Ocean Science (OCE).
Adapted from materials provided by University of Miami Rosenstiel School of Marine & Atmospheric Science.

Fish reproduction impairemet due to low oxygen at coastal waters

Low oxygen levels in coastal waters interfere with fish reproduction by disrupting the fishes' hormones, a marine scientist from The University of Texas at Austin Marine Science Institute has found।

Incidents of seasonal low levels of oxygen, known as hypoxia, have increased dramatically in coastal waters throughout the world over the past few decades, largely as a result of increased run-off from human agricultural and industrial activities. Hypoxia's long-term impact on marine animal populations is unknown.
Dr. Peter Thomas found that both male and female fish collected from seasonally hypoxic waters in Florida's Pensacola Bay estuaries had little ovarian and testicular growth, low egg and sperm production, and low levels of reproductive hormones during a time a year when they would normally be increasing in preparation for reproduction.
"This study provides the first clear evidence that a wild population of estuarine fish has experienced reproductive impairment through hypoxia," said Thomas, professor of marine science. "We rarely find such a dramatic reproductive impairment in both male and female fish collected from degraded environments, such as those contaminated with pollutants."
Laboratory studies showed that hypoxia caused endocrine disruption through decreasing levels in the brain of a chemical important for brain function called serotonin. The decrease in serotonin was caused by a decrease in an enzyme that plays a role in the serotonin synthesis pathway.
Atlantic croaker is one of the most common inshore fish species along the coasts of the southeastern Atlantic Ocean and Gulf of Mexico, and Thomas said that the croaker is representative of many inshore fish.
"This study suggests that when persistent coastal hypoxia occurs, there is a potential long-term threat to fish populations and fishery resources," said Thomas. "With worldwide increases in hypoxia, it's something we must be concerned about, because so many people rely on fishing for their livelihood."
Thomas' future studies will aim to further elucidate the effects of hypoxia on fish endocrine and reproductive systems at the molecular level. He is also pursuing similar work on reproductive impairment in croaker from hypoxic waters surrounding the so-called "Dead Zone" off the coast of Louisiana, which is an area of almost no oxygen that this year covered 7,900 square miles.
Thomas' research was recently published online in Proceedings of the Royal Society B.
Funding for this research was provided by the U.S. Environmental Protection Agency. Dr. Md. Saydur Rahman Dr. Izhar Khan and James Kummer contributed to the research.
Note: This story has been adapted from a news release issued by University of Texas at Austin.

Outbreak kills 250,000 fish at hatchery

About 250,000 rainbow trout died in a sudden disease outbreak at a southwestern Idaho fish hatchery, a loss of about 8 percent of Idaho's annual output of catchable-sized trout. It was the second such outbreak of ichthyophthirius multifilis in as many years at the state Department of Fish and Game hatchery in Nampa. Officials say it likely resulted when stress from overcrowding weakened the fish, making them more susceptible to the parasite.The outbreak happened in January, but became public this week because the state agency is trying to manage remaining stocks of 6- to 8-inch fish at its five other hatcheries to make certain lakes and streams still get enough fish to satisfy anglers.Tom Frew, who manages the Nampa site, said careful manipulation of stocks at other facilities should make up for the losses. He said scientists are assessing just what went wrong. One possible change to avoid future outbreaks, he said, might be to reduce the number of fish raised at the Nampa hatchery and increase it elsewhere."The parasite multiplies very rapidly," said Frew, who estimated the cost of the die-off at $40,000, including fish food and labor. "By the time we see symptoms, the disease has a pretty strong hold on the animal."In all, the state produces about 3 million catchable-sized trout every year, among some 26 million total fish produced.The parasites, commonly referred to as "ich," are visible as white spots on a fish's gills and skin. As their attack intensifies, fish "flash," or turn on their sides as they try to scrape off the bugs.The fish become lethargic and eventually die. In the end, the parasites become so numerous on an infected fish's gills that it simply smothers.In addition to the outbreaks in Nampa, a sudden thunderstorm last year washed debris-laden runoff into Idaho's Sawtooth hatchery near Stanley, weakening chinook salmon and making them more susceptible to the parasite, Frew said."Normally, they're capable of sloughing off the parasite," Frew said. "Anytime fish are in captivity, in the aquarium industry, or where the fish are in a closed system" there's a danger of an outbreak.Nampa's hatchery has 10 raceways, all fed by artesian wells. The disease was found in all the raceways.Due to the hatchery's design, it's not possible to empty the raceways of water to sterilize them, leaving the parasite present year after year.Though hatchery officials haven't changed their fish-raising regimen in a dozen years, Frew said, the disease appears to have gained a more lethal toehold in 2006 and 2007."For some reason, the last couple of years, we've had some problems with ich at the Nampa hatchery," Frew said. "There's not really a lot we could do, without a complete rebuild of the Nampa hatchery."