Oceanographic Linkages Indicate an Alternative Route for Eel Larval

European eel larvae are generally believed to initially follow a westerly drift route into the Gulf Stream, but new research results on bio-physical linkages in the Sargasso Sea point to a shorter route towards Europe.

As both European and American eel populations are in a drastic decline, there is an urgent need for a better understanding of the early oceanic phase of their life cycle.

New findings from the Danish Galathea 3 Expedition to the eel's spawning sites in the Sargasso Sea now point to an alternative route for larval drift towards Europe and shed light on the conditions for larval growth and feeding

Scientific results published in Proceedings of the Royal Society show the importance of including the climatic influence on oceanic processes when assessing the conditions for the early life of eel and the background of a declining recruitment to the eel populations.

"Our studies in the Sargasso Sea demonstrate a significant relationship between the physical and biological conditions in the area. A front established where warm tropical waters meet colder North Atlantic water has a key role in the larval life of eel" says Senior Scientist Peter Munk from DTU Aqua -- National Institute of Aquatic Resources, Technical University of Denmark.

The front retains eel larvae within a zone of enhanced feeding conditions and influences their drift towards the continent.

European eel larvae are generally believed to initially follow a westerly drift route from the spawning site and subsequently drift with the Gulf Stream. But the study's demonstration of a strong linkage between larval distributions and the fronts in the area suggests another possibility.

The front between the warm and cold waters leads to a current which, contrary to the predominant currents in the area, is directed eastward, and the distribution of larvae indicates that they could use this "subtropical counter current" as a shorter and faster route towards Europe.

These oceanic processes are affected by climate change, and the study shows the importance of including them in the understanding of the life cycle completion of eel and the fluctuations in stock sizes.

Other research finding from the Galathea 3 Expedition has just been published in Biology Letters and describes the diet of eel larvae. The scientists brought home very small eel larvae (5-25 mm) from the Sargasso Sea to find out what they actually eat.

It has been assumed that the eel's long journey to the Sargasso Sea was linked to the feeding opportunities in the area for the newly hatched eel larvae. So far, knowledge about what and if eel larvae eat has been sparse, as only very few larvae have been found with identifiable prey items in the gut.

The eel larvae from the Galathea 3 Expedition have now been analysed using DNA barcoding, which makes it possible to identify the various plankton organisms found in the otherwise unidentifiable gut contents.

The findings show that even the smallest eel larvae eat remarkably diverse marine organisms. Gelatinous zooplankton, in particular, e.g. small jellyfish, play an important role in their diet. The study suggests that the frontal zone in the Sargasso Sea provides ample feeding opportunities for the eel larvae.

The findings relating to larval diet may be very useful in connection with artificial reproduction and rearing of the European eel, where one of the major questions is what to feed to the eel larvae.

The studies of larval diet were conducted by Associate Professor Lasse Riemann from the University of Copenhagen in collaboration with, amongst others, scientists from DTU Aqua.
P. Munk, M. M. Hansen, G. E. Maes, T. G. Nielsen, M. Castonguay, L. Riemann, H. Sparholt, T. D. Als, K. Aarestrup, N. G. Andersen, M. Bachler. Oceanic fronts in the Sargasso Sea control the early life and drift of Atlantic eels. Proceedings of the Royal Society B: Biological Sciences, 2010; DOI: 10.1098/rspb.2010.0900

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Deep sea fish 'mystery migration' across Pacific Ocean

Deep sea fish species found in the north Pacific Ocean have mysteriously been caught in the southwest Atlantic, on the other side of the world.It is unclear how the animals, a giant rattail grenadier, pelagic eelpout and deep sea squid, travelled so far. Their discovery 15,000km from their usual home raises the possibility that deep sea currents can transport animals from one polar region to another. Details are published in the journal Deep Sea Research part I. "These findings were completely unexpected," says Dr Alexander Arkhipkin of the Falkland Islands Fisheries Department, based in Stanley, on the Falkland Islands in the southwest Atlantic Ocean.Watch extraordinary footage of a rarely seen giant deep sea fish See strange jellies discovered in the icy depths Explore the deep sea Since 1987, the Falkland Islands Fisheries Department has performed surveys of fish caught by commercial and research fishing trawlers travelling above the Patagonian Shelf and slope around the islands. Commercial longline catches of Patagonian toothfish have also been examined. Recently, these catches have brought to the surface animals previously unknown in the southwest Atlantic. For example, Dr Arkhipkin and colleagues Dr Vladimir Laptikhovsky and Dr Paul Brickle report a 81cm-long grenadier fish belonging to the genus Albatrossia caught by the longline fishery set to catch Patagonian toothfish. Another deepwater trawl caught a small 15cm-long pelagic eelpout at a depth of 1000m.Experts have identified this fish as being a member of the slipskin species Lycodapus endemoscotus. Previously both species were only known from the deepwaters of the north Pacific Ocean. A small immature 11cm-long north Pacific gonate squid Gonatopsis octopedatus was also recovered from a trawl south of the Falkland Islands. Genetic analyses confirmed the identification, which is the first time any member of this squid genus has been recorded in the southern hemisphere. The catches are the first time that such deepwater species have been caught so far from their natural habitat. All three species habitually live in the deep waters of the north Pacific, at depths greater than 600-1000m. That makes it extremely unlikely that the fish and squid could have become trapped in ballast water used by ships, and transported around the world. "We would not expect that relatively slow deepwater fish and squid might travel so far from their common habitats," says Dr Arkhipkin.All three species live above the seafloor, and none of the three are known to habitually migrate, just as tuna and whales do. Far more likely is that each animal was transported thousands of kilometres by deepwater currents. These flow south, across the equator, moving past South America underneath another northbound flow called the Humboldt Current. Finally, this flow mixes with another called the Upper Circumpolar Deep Water to pass through the Drake Passage, whcih separates South America and Antarctica, to the Southwest Atlantic.Visit Deep Sea Research part I to read more about the travelling deep sea species Such deep water currents flow slowly, so it may take a few years for a long-lived fish, or even several generations of short-lived fish or squid to migrate the whole way. Dr Arkhipkin says the catches may force scientists to reevaluate their ideas about the distribution and movements of deepwater species. Though there is no evidence to support the idea, Dr Arkhipkin speculates that climate change may be influencing the deepwater currents, facilitating the novel spread of such animals.

New System Helps Explain Salmon Migration

A new acoustic telemetry system tracks the migration of juvenile salmon using one-tenth as many fish as comparable methods, suggests a paper published in the January edition of the American Fisheries Society journal Fisheries. The paper also explains how the system is best suited for deep, fast-moving rivers and can detect fish movement in more places than other tracking methods.

The Juvenile Salmon Acoustic Telemetry System (JSATS) estimated the survival of young, ocean-bound salmon more precisely than the widely used Passive Integrated Transponder (PIT) tags during a 2008 study on the Columbia and Snake rivers, according to the results of a case study discussed in the paper. The paper also concludes that fish behavior is affected least by light-weight JSATS tags compared to larger acoustic tags.
"Fisheries managers and researchers have many technologies to choose from when they study fish migration and survival," said lead author Geoff McMichael of the Department of Energy's Pacific Northwest National Laboratory.
"JSATS was specifically designed to understand juvenile salmon passage and survival through the swift currents and noisy hydroelectric dams on the Columbia River," McMichael continued. "But other systems might work better in different circumstances. This paper demonstrates JSATS' strengths and helps researchers weigh the pros and cons of the different fish tracking methods available today."
Scientists at PNNL and the U.S. Army Corps of Engineers' Portland District co-authored the paper. PNNL and NOAA Fisheries began developing JSATS for the Corps in 2001.
JSATS is an acoustic telemetry system that includes the smallest available acoustic transmitting tag, which weighs 0.43 grams. Its battery-powered tags are surgically implanted into juvenile salmon and send a uniquely coded signal every few seconds. Receivers are strategically placed in waterways to record the signal and track when and where tagged fish travel. A computer system also calculates the precise 3-D position of tagged fish using data gathered by the receivers.
PIT tags are also implanted into juvenile salmon for migration and survival studies, but don't use batteries to actively transmit signals. Instead, PIT tags send signals when they become energized while passing by PIT transceiver antennas.
For the paper's case study, researchers implanted 4,140 juvenile Chinook salmon with both JSATS and PIT tags. They also placed just PIT tags inside another 48,433 juveniles. All of the case study's tagged fish were released downstream of Lower Granite Dam on the Snake River in April and May 2008.
A significantly greater percentage of JSATS tags were detected than PIT tags, the case study demonstrated. For example, about 98 percent of JSATS-tagged fish were detected at Ice Harbor Dam on the Snake River. About 13 percent of PIT-tagged fish were detected in the same stretch of river. As a result, studies using JSATS require using roughly one-tenth as many fish as those employing PIT tags, which helps further conserve the salmon population.
Survival estimates were similar between JSATS and PIT tags. Forty-eight percent of the JSATS-tagged fish were estimated to have survived migration between Lower Granite Dam and Bonneville Dam, which is the last dam on the Columbia before the Pacific Ocean. For PIT-tagged fish, 43 percent were estimated to have reached the same area.
Having flexibility in where receivers can be placed is advantageous, the authors reported. JSATS receivers can be located in both rivers and dams, while PIT antennas usually can only go inside fish bypasses at dams. Researchers can estimate fish survival for an entire river system when receivers are placed in more locations, the paper explains.
The team also compared JSATS' technical features with those of another acoustic telemetry system, the VEMCO system being used for the Pacific Ocean Shelf Tracking (POST) project along North America's West Coast. The VEMCO system is best suited for use in the slow-moving, open ocean when observing small numbers of large fish, the authors wrote. In contrast, JSATS was developed to study the migration of larger quantities of small juvenile fish in fast-moving rivers.
A key difference between the JSATS and VEMCO systems is dry tag weight. JSATS tags weigh 0.43 grams and are the smallest acoustic tags available. VEMCO tags that have been used in Columbia River juvenile salmon weighed 3.1 grams. Previous research shows fish can bear a tag that weighs up to 6.7 percent of their body weight without significant adverse survival effects. That means JSATS tags can be implanted into fish as light as 6.5 grams, while VEMCO tags should be used in fish that weigh no less than 46.3 grams.
Another advantage of JSATS is that it is non-proprietary and available for anyone to manufacture or use. Because several companies have been able to competitively bid for the opportunity to produce the system's components, its cost has dropped in recent years. JSATS tags, for example, have gone from $300 per tag in 2005 to $215 in 2008. And JSATS tags cost $40 to $135 less than other commercially available acoustic tags in 2008. Proprietary interests have hindered the development of acoustic telemetry equipment in certain areas, the team wrote.
"JSATS has helped us get a clearer, more complete picture of how salmon migrate and survive through the Columbia and Snake rivers to the Pacific Ocean," McMichael said. "But we're continuing to develop JSATS and hope others will find it useful in studies of other aquatic animals. There's an opportunity for all aquatic telemetry technologies to be improved."

Whales migrate along coast

It's the end of December, and that can only mean one thing: The gray whales are on the move.

Over the next few weeks, around 19,000 whales will cruise by the Oregon Coast on their way to Baja, Mexico.

They started their journey out of Alaskan waters in October and are just now passing our fair state, and the biggest number of them pass in the week starting Saturday.

"The whales pass the entire state; they don't just pass the Whale Center," said Morris Grover, an interpretive ranger and coordinator of the whale-watching program for Oregon State Parks. "You can go almost anywhere (to see them) with this many whales because they cover the state."

The whales are headed to warmer waters to mate and give birth, he said, and the males tag along for fun.

"All of them migrate. It's kind of like happy hour at the bar — if all the women are down there, guess where the men are going to be," he said. "They don't couple up (in Alaska), but when they get into warm water, they go, 'Oh, this is a nice place to play. I'm here. All the women are here.'"

The whales travel at four to five miles per hour, he said, about the speed of us when we walk. It's also a tough trip because once the whales pass Oregon, they are effectively fasting because their food doesn't grow in warm water.

"There's maybe a little snacking in Northern California," he said.

It is, in fact, that hunger that prompts them to leave Mexican waters to head back up to Alaska in the spring.

Anyway, you can see them anywhere on the coast if the weather is calm and the waves are small, but you may want to stop by the Whale Watching Center, 703 S Highway 101, in Depoe Bay where you can watch movies and chat with Grover about whales

A different kind of fish toss: Planting dead salmon to enrich a watershed

Humans aren't the only ones who benefit when large runs of salmon return to rivers and streams. Joel Davis/The OregonianThe nutrients and organic matter deposited by salmon carcasses are critical to the health of Pacific Northwest watersheds.For the watersheds of the Pacific Northwest, dead salmon -- rotting, stinky, gross -- provide crucial nutrients to support diverse, complex freshwater environments. Pacific salmon complete almost all of their growth while living in the ocean. When they migrate back to natal streams and die, decomposition releases calcium, phosphorous and nitrogen into the water, enriching streams with nutrients that feed algae, aquatic insects and juvenile salmon. The salmon goodness spreads to plants and wildlife. Studies of some old confer trees growing near rivers have revealed marine nitrogen isotopes that could only have come from rotting salmon. But recent declining salmon runs have raised concerns about the health of watersheds as they lose those nutrients. Researchers believe that nutrient deficiencies -- because of fewer decomposing salmon -- actually hinder the recovery of salmon and steelhead populations. That's where the annual Sandy River Basin Watershed Council "salmon toss" comes in. Thousands of salmon carcasses from the Sandy Fish Hatchery on Cedar Creek are "planted" in and along tributaries of the Sandy River in the late fall. The work is dirty -- organizers joke that they should try out for Discovery Channel's popular "Dirty Jobs" show. But it always draws lots of volunteers. On Saturday, crews from the Oregon Department of Fish and Wildlife and the Mount Hood National Forest will join with about 40 students from Sam Barlow High School to dump fish carcasses near Lost Creek Campground. Sam Barlow teens have helped with the salmon toss the past four years. The six-year-old program aims to increase the production of naturally spawning populations of salmon and steelhead in the Sandy River basin, to increase the production of other native fish, to provide nutritional benefits for plants and wildlife, and to encourage community watershed stewardship.The salmon carcasses come from the Sandy Fish Hatchery. Early in the season, the returning coho salmon were harvested, flash-frozen and donated to the Oregon Food Bank. But later arrivals, often used for the breeding program, have been stored in a 40-foot-long refrigerated trailer to become food for the watershed ecosystem. The salmon have their tails cut off so they aren't included in stream counts of spawning salmon. Volunteers distributed almost 40,000 pounds of salmon carcasses along streams in 2006 and 2007.

North Atlantic Fish Populations Shifting As Ocean Temperatures Warm

About half of 36 fish stocks in the Northwest Atlantic Ocean, many of them commercially valuable species, have been shifting northward over the last four decades, with some stocks nearly disappearing from U.S. waters as they move farther offshore, according to a new study by NOAA researchers.

Their findings, published in the journal Marine Ecology Progress Series, show the impact of changing coastal and ocean temperatures on fisheries from Cape Hatteras, N.C., to the Canadian border.
Janet Nye, a postdoctoral researcher at NOAA's Northeast Fisheries Science Center (NEFSC) laboratory in Woods Hole, Mass. and the lead author of the study, looked at annual spring survey data from 1968 to 2007 for stocks ranging from Atlantic cod and haddock to yellowtail and winter flounders, spiny dogfish, Atlantic herring, and less well-known species like blackbelly rosefish. Historic ocean temperature records and long-term processes like the Atlantic Multidecadal Oscillation and the North Atlantic Oscillation dating back to 1850 were also analyzed to put the temperature data into context.
"During the last 40 years, many familiar species have been shifting to the north where ocean waters are cooler, or staying in the same general area but moving into deeper waters than where they traditionally have been found," Nye said. "They all seem to be adapting to changing temperatures and finding places where their chances of survival as a population are greater."
Nye and coauthors Jason Link, Jonathan Hare and William Overholtz of NEFSC selected the 36 species to study because they were consistently caught in high numbers in the Center's annual spring bottom trawl survey. They also represented a wide range of taxonomic groups, and were known to be commercially or ecologically important. NEFSC, headquartered in Woods Hole, conducts annual spring and fall trawl surveys and has the world's longest time series of standardized fishery population data.
The researchers looked at where the fish were caught and their biomass, or the estimated total weight of the population, in each year of the survey. For each stock they estimated the center of abundance, average depth, the range or area that the stock occupied, and the average temperature at which each stock was found.
They also took into account fishing pressures on the species over time, as well as natural cycles in ocean temperature. Ocean temperatures have increased since the 1960s and 1970s, and the authors found significant changes in species distribution consistent with warming in 24 of the 36 stocks studied.
Ten of the 36 stocks examined had significant range expansion, while 12 had significant range contraction. Changes in a species range can be affected by both temperature changes and fishing pressure, with heavily fished stocks appearing more sensitive to climate change and often showing a larger shift. Seventeen of the 36 stocks occupied increasingly greater depths, and three stocks occupied increasingly shallower waters. However, the temperature at which each stock was found did not change over time, suggesting that fish are moving to remain within their preferred temperature range.
Fish species can respond to changes in ocean temperature in a variety of ways. The stock can move poleward to avoid warmer water temperatures, or move into deeper waters than they have previously been found. If fish cannot change their geographic or depth distribution, there may be changes in growth, reproduction and mortality rates. As a result, the size of the population may increase or decrease depending on the temperature preference of the species. Most species in the study were found to be responding to warming ocean temperatures in one of these ways.
"The fact that we see responses in many species consistent with what you would expect with warming, but in different types of species that have experienced different historical fishing pressure, suggests that we are already witnessing the response of fish to a warming scenario," Nye said. "The community structure is changing from cool-water to warm-water fish species. These trends will likely continue".
While consumers will find familiar fish species at their local fish markets for the foreseeable future, fisherman may have to travel farther to catch some species until eventually it will not be economical.
"Consumers in the Northeast, for example, may eventually start seeing less familiar species like Atlantic croaker at local markets and on restaurant menus as southern and Mid-Atlantic species move northward into New England waters," Nye said. "The fish appear to be adapting to a changing environment, and people will as well over the next few decades."
The authors say the study has implications beyond the Northeast U.S. "It is another example of the need for an ecosystem-based management approach to our fisheries," said co-author Jason Link, a fisheries biologist at NEFSC's Woods Hole laboratory. "Many factors, temperature among them, influence the status of a fish stock, and we need to be aware of all of those factors and consider them in management decisions. Looking at 'the big picture' helps put each piece of the puzzle in perspective."
Adapted from materials provided by NOAA Fisheries Northeast Fisheries Science Center.

Scientists Map Fish Habitat And Movements At Gray's Reef Marine Sanctuary

Two related research expeditions by NOAA scientists to track the habitat preferences and movements of fish at Gray’s Reef National Marine Sanctuary may help managers protect overfished species such as red snapper and grouper.

Research from the two expeditions appears in the current online edition of the peer-reviewed Bulletin of Marine Sciences.
“It’s important to know exactly what areas to protect,” says Matt Kendall, principle investigator on the habitat mapping project. “Certain fish gravitate to certain bottom types. If you want to protect red snapper, for example, you have to know where they live.”
The projects tracking fish movements through telemetry will help researchers better understand the basic “life histories” of these fish. The South Atlantic Fishery Management Council, citing the “lack of basic management data as a major obstacle” to the successful management of these species, has recently called for a total ban on red snapper fishing to help restore stock levels. The ban is pending final approval.
According to the latest reports from NOAA Fisheries, black sea bass, red snapper, red grouper, and gag are among the region’s overfished species. These studies are helping researchers better understand the movements and habitat preferences of these species, and their potential vulnerability to fishing. This knowledge will contribute to stock management and recovery of overfished species.
In the first of the two expeditions, researchers confirmed the importance of limestone ledges, which make up only one percent of Gray’s Reef and only slightly more of the entire continental shelf of the southeastern United States. Scientists noted a distinct correlation between ledge characteristics such as height and degree of undercut to the types and numbers of fish found at the ledge. This information can help prioritize reef areas for management.
For example, gag and scamp, two grouper species prized by recreational fishermen, are nearly always present at ledges extending from a wall or structure by 12-18 inches – a ledge type that represents only a tiny fraction of limestone ledges in the sanctuary. Red snapper are typically present near ledges extending a minimum of 27 inches, a ledge type that also represents only a small portion of the limestone ledges in the sanctuary.
Kendall and his colleagues are not only mapping the relative value of Gray’s Reef habitat for various fish communities, but also tracking how fish move around the sanctuary. Over the last two years, Kendall and his team have implanted tracking devices in fish which are being used in conjunction with sensors placed throughout part of the sanctuary.
These sensors will help them understand, for example, which fish are “homebodies” and which fish travel more widely. The data so far reveals that grouper tend to stay close to their preferred ledges, while snapper venture farther from their home territory.
The team’s research not only has implications for the management of Gray’s Reef Sanctuary, but also for the management of reefs throughout the South Atlantic region. “If the fish have these kinds of specific relationships to the bottom habitat at Gray’s Reef, there is no reason to think that these same relationships don’t exist elsewhere in the southeastern United States,” Kendall said.
NOAA understands and predicts changes in the Earth’s environment, from the depths of the ocean to the surface of the sun, and conserves and manages our coastal and marine resources.
Journal reference:
Matthew S. Kendall, Laurie J. Bauer, and Chris F. G. Jeffrey. Influence Of Hard Bottom Morphology On Fish Assemblages Of The Continental Shelf Off Georgia, Southeastern USA. Bulletin of Marine Sciences, 2009; 84(3): 265%u2013286
Adapted from materials provided by National Oceanic And Atmospheric Administration.

Salmon Migration Mystery Explored On Idaho's Clearwater River

Temperature differences and slow-moving water at the confluence of the Clearwater and Snake rivers in Idaho might delay the migration of threatened juvenile salmon and allow them to grow larger before reaching the Pacific Ocean.

A team of Northwest researchers are examining the unusual life cycle of the Clearwater's fall Chinook salmon to find out why some of them spend extra time in the cool Clearwater before braving the warm Snake. The Clearwater averages about 53 degrees Fahrenheit in the summer, while the Snake averages about 71. The confluence is part of the Lower Granite Reservoir -- one of several sections of slow water that are backed up behind lower Snake and Columbia river dams -- that could reduce fish's cues to swim downstream.
The delayed migration could also mean Clearwater salmon are more robust and survive better when they finish their ocean-bound trek, said Billy Connor, a fish biologist with the U.S. Fish & Wildlife Service.
"It may seem counterintuitive, but the stalled migration of some salmon could actually help them survive better," Connor said. "Juvenile salmon may gamble on being able to dodge predators in reservoirs so they can feast on the reservoirs' rich food, which allows them to grow fast. By the time they swim toward the ocean the next spring, they're bigger and more likely to survive predator attacks and dam passage."
Scientists from the U.S. Geological Survey, the U.S. Fish & Wildlife Service, the Department of Energy's Pacific Northwest National Laboratory and the University of Washington are wrapping up field studies this fall to determine if water temperature or speed encourage salmon to overwinter in the confluence and in other reservoirs downstream. The Bonneville Power Administration is funding the research to help understand how Snake and Columbia River dams may affect fish.
USGS and USFWS are tracking fish movement by implanting juveniles with radio tags, which are more effective in shallow water. PNNL is complementing that effort with acoustic tags, which work better in deeper water. PNNL is also contributing its hydrology expertise to measure the Clearwater and Snake rivers' physical conditions. UW is providing the statistical analysis of the tagging.
"Fall Chinook salmon on the Clearwater River have a fascinating early life history that may contribute to their successful return as adults," said PNNL fish biologist Brian Bellgraph. "If we can support the viability of such migration patterns in this salmon subpopulation, we will be one step closer to recovering the larger fall Chinook salmon population in the Snake River Basin."
Scientists used to think all juvenile fall Chinook salmon in the Clearwater River migrated to the ocean during the summer and fall after hatching in the spring. But researchers from USGS, USFWS and the Nez Perce Tribe began learning in the early 1990s that some stick around until the next spring. Similar delays have also been found in a select number of other rivers, but this is still the exception rather than the rule. The Clearwater is unique because a high number -- as much as 80 percent in some years -- of its fall Chinook salmon don't enter the ocean before they're a year old.
To better understand how fish react to the river's physical conditions, scientists are implanting juvenile salmon with the two types of small transmitters that emit different signals. The transmitters -- commonly called tags -- are pencil eraser-sized devices that are surgically implanted into young fish 3.5 to 6 inches in length. Specially designed receivers record the tags' signals, which researchers use to track fish as they swim. The gathered data helps scientists measure how migration is delayed through the confluence.
Radio tags release radio waves, which are ideal to travel through shallow water and air. And acoustic tags emit higher-frequency sounds, or "pings," that more easily move through deeper water. The acoustic tags being used are part of the Juvenile Salmon Acoustic Telemetry System, which PNNL and NOAA Fisheries developed for the U.S. Army Corps of Engineers.
Together, fish tagged with both acoustic and radio transmitters help create a more comprehensive picture of how the river affects fish travel. The location data can also indicate how well fish fare. If a tag's signal stops moving for an extended period, the fish in which it was implanted might have died. Researchers examine the circumstances of each case to determine the fish's fate.
This study is a unique example of how both tag technologies can jointly determine the survival and migration patterns of the relatively small juvenile fall Chinook salmon. The size of transmitters has decreased considerably in recent years; further size reductions would allow researchers to study even smaller fall Chinook salmon. This could provide further insight into this mysterious migration pattern.
Beyond the fish themselves, researchers will also examine water temperature and flow to determine what correlation the river's physical conditions may have with the fish movement. Salmon use water velocity and temperature as cues to guide them toward the ocean. But the Lower Granite Dam's reservoir, which extends about 39 miles upriver from the dam to Lewiston, makes the water in the Clearwater River's mouth move slowly. Researchers suspect the slow water may encourage some fall juvenile Chinook salmon to delay their journey and spend the winter in the confluence.
To test this hypothesis, PNNL scientists take periodic velocity measurements in the confluence from their research boat. Submerged sensors have recorded water temperatures every few minutes between about June and January since 2007. Both sets of information will be combined to create a computational model of the fish's river habitat.
This study's results could be used to modify river water flow to improve fish survival. The Clearwater's Dworshak Dam already helps manage water temperature by strategically releasing cool water toward the Snake. The waters form thermal layers -- with the Snake's warm water on top and the Clearwater's cool liquid below -- that fish move through to regulate their body temperatures.
The Nez Perce Tribe began studying fall Chinook salmon in the lower Clearwater River in 1987. USGS and USFWS joined the effort in 1991, when the Snake River Basin's fall Chinook salmon were first listed under the Endangered Species Act. PNNL and UW joined the study in 2007. The Bonneville Power Administration is paying for the study.
Adapted from materials provided by DOE/Pacific Northwest National Laboratory.

Unlocking The Mystery Of European Eel Migrations

The spawning migration of European eels from rivers and brackish waters in Europe to the Sargasso Sea is one of the most impressive feats of animal migration and orientation. Yet after over 2000 years of study it is still a mystery to be solved. But, thanks to research ongoing since 2006, scientists are getting closer to a full understanding.

Dr. Kim Aarestrup, National Institute of Aquatic Resources and Professor David Righton, Centre for Environment Fisheries and Aquaculture Science are happy. Together with colleagues and by the use of modern satellite tracking technology, they have solved an important part of the eel mystery: What happens when European eels stir in dark autumn nights and leave European rivers and coasts.

To coax these secrets from the eels, scientists fitted 22 European eels with a prototype Pop up Satellite Tag (PSAT) in 2006. The tags register and store light, depth and temperature. The eels were tagged as part of the Danish Galathea project, but the data from the tags has been analysed, and the tagging work continued in the EU and national government-funded EELIAD project. The first results were recently published in the journal Science.

New surprising knowledge in several ways

Dr Kim Aarestrup, who is a Senior scientist at the Technical University of Denmark, National Institute of Aquatic Resources (DTU Aqua), and leader of the tagging work in the EU EELIAD project (see below) says: "This is a brilliant result in many different ways. Eels are difficult to follow once they leave European shores, so their behaviour as they migrate to their spawning grounds is almost a complete mystery. The study has added to the understanding of the migration and surprised the scientists in several ways. First of all, the eels don’t swim directly towards the spawning grounds in the Atlantic Ocean south of Bermuda. Secondly, our data shows that the eel every day dives down at daytime, only to ascend back towards the surface at night, a recurring depth change of several hundred meters. Thirdly, the results show that eel on this first stage of the migration swims too slow to reach the hypothesized spawning place at the assumed spawning time in April.”

The eels that migrated longest had swum more than 1000 km from the Irish coast. Kim Aarestrups says: ”It is very interesting that eels do not migrate directly towards the Sargasso Sea, but instead takes a more southern route towards the Azores. Researchers had previously speculated that eels should migrate south of the Azores to catch a ride on the south and west going currents and this way speed up their migration. Perhaps they were right!".

Goes deep at day

Data from the tags reveals a distinct diel migration pattern. At night the eels swim in relatively warm water at 200-300 m depth, but at dawn they dive down into colder deep water at up to 1000 m depth. This caused astonishment.

"This is entirely new knowledge and we can only speculate on why eels do this. We hypothesize that the observed pattern may reflect thermoregulation. Eels may move into warm water at night to maintain sufficiently high metabolic rates and swimming speeds and then descend into deeper and colder waters to delay the maturation of their gonads. This would mean that they maintain their hydrodynamic profile for most of their long migration, rather than becoming bloated with eggs which would then increase the energy needed to swim,” says David Righton, who is a Professor at Principal Scientific Officer at the Centre for Environment Fisheries and Aquaculture Science (Cefas) and Coordinator of the project.

The need to completely understand the eel lifecycle is more necessary than ever, because the eel population has dropped precipitously in the last three decades and the reasons are unknown. Furthermore, the information may be important for the current work of reproducing the eels artificially. Currently, the maturation is 'forced' by injecting hormones into adult eels, but maybe this new data can help to find a way to mature the eels without injecting hormones.

About European Eels

European eel (Anguilla anguilla) is an important fish species. Eel fisheries generate a total annual income of ~€200 million Euro, and employ over 25,000 European citizens in 15 countries. Eel catches have been halved – from 40,000 tonnes in the last three decades to less than 20,000 tonnes today and the recruitment of elvers has dropped even more. The cause of this decline is not known, and more information is needed about eel biology and ecology to help conserve and recover European stocks.

The tagging project

The eels detailed in the Science study were tagged as part of the Danish Galathea project but the data collected has been analysed and the tagging continued in the EU and national government-funded EELIAD (an acronym of European Eels in the Atlantic: Assessment of Their Decline) project. EELIAD is a four-year, €4million collaborative scientific research project, between 12 different institutes in Europe, aiming to resolve some of the mysteries of eel biology. The information it gleans will help conserve European eel stocks.

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Journal reference:

1. Kim Aarestrup et. al. Oceanic Spawning Migration of the European Eel (anguilla anguilla). Science, vol 325, 25; September 25, 2009 DOI: 10.1126/science.1178120

Adapted from materials provided by Technical University of Denmark (DTU).

Blue Whales Re-establishing Former Migration Patterns

The planet's largest animal may be returning to pre-whaling feeding grounds. Scientists have documented the first known migration of blue whales from the coast of California to areas off British Columbia and the Gulf of Alaska since the end of commercial whaling in 1965.In the scientific journal Marine Mammal Science, researchers from Cascadia Research Collective in Washington state, NOAA's Southwest Fisheries Science Center in California, and Canada's Department of Fisheries and Oceans identified 15 separate cases where blue whales were seen off British Columbia and the Gulf of Alaska. Four of the whales were identified as animals previously observed off the coast of California, suggesting a re-establishment of a historical migration pattern.Researchers made this identification by comparing photographs of blue whales taken in the north Pacific Ocean since 1997 with a library of nearly two thousand photographs of blue whales off the West Coast. A positive match was determined based on pigmentation patterns in skin color and shape of the dorsal fin.Blue whales were severely depleted during commercial whaling activities during the early 1900's in the north Pacific and along the West Coast as far south as Baja California.Formerly large populations of blue whales in the north Pacific never rebounded after commercial whaling ended while those animals off southern California have apparently fared much better.Scientists are still not certain exactly why blue whales are now beginning to migrate from southern California to the north Pacific Ocean although changing ocean conditions may have shifted their primary food source of krill further north.Blue whales are thought to be the largest animal ever to have existed on earth, reaching lengths of nearly 100 feet. They were nearly hunted to extinction throughout the world and are currently listed as endangered under the U.S. Endangered Species Act and as endangered on the red list of the International Union for the Conservation of Nature. There are an estimated 5,000 to 12,000 animals remaining today, with the largest population of approximately 2,000 off the U.S. West Coast.NOAA National Marine Fisheries Service.

Blue whales return to coast

After avoiding B.C.'s coast for decades, blue whales are returning to our waters to feed in the areas where they were once hunted to near extinction.Scientists hoped the recent sightings meant an increase in the population of the highly endangered whales, but an article to be published this month by the U.S. Marine Mammal Science journal suggests the whales have migrated north from California, following the tiny shrimp on which they feed.It's a pattern the massive whales might have followed for decades, chasing krill that move with the 20 or 30-year cycle of cool ocean water."It's good news to see these whales back in our waters," said John Ford, co-author of the article and a whale researcher with the federal fisheries and oceans department."It's encouraging that the whales are out there using this habitat. Now we have to find out what areas are important to them and then try to protect them."Accidental collisions with ships pose the biggest threat to blue whales, he said.In August 2007, Ford was part of survey team that spotted five blue whales off the Queen Charlotte Islands. Researchers believe about 2,000 of the sleek, steel-grey whales live off the west coast, between Alaska and Mexico. Worldwide, there are only about 10,000 blue whales.

DNA Used To Study Migration Of Threatened Whale Sharks

Whale sharks -- giants of the fish world that strike terror only among tiny creatures like the plankton and krill they eat -- are imperiled by over-fishing of the species in parts of its ocean range.

That threat is underscored in a new study from geneticists led by Jennifer Schmidt, University of Illinois at Chicago associate professor of biological sciences, reported online April 7 in the journal PLoS One.
Schmidt and her colleagues studied the DNA of 68 whale sharks from 11 locations across the Indian and Pacific Oceans and the Caribbean Sea -- an area that covers most of the shark's known range. Results showed little genetic variation between the populations, which indicates migration and interbreeding among far-flung populations of the big fish.
"Our data show that whale sharks found in different oceans are genetically quite similar, which means that animals move and interbreed between populations," said Schmidt. "From a conservation standpoint, it means that whale sharks in protected waters cannot be assumed to stay in those waters, but may move into areas where they may be in danger."
A tropical fish that can grow 50 feet or longer and weigh over 20 tons, a whale shark's range can span oceans. They do not breed until they are about 25 to 30 years old, so it will take a long time for the species to recover from recent population declines.
Whale sharks are listed as threatened, but not every country protects them. The large animals are especially prized by fishermen for meat and fins used in soup.
Little is known about the shark's biology, perhaps because they have been studied primarily near shore, while mature animals may breed and give birth out in the open ocean. Nor is much known about neonatal or juvenile sharks, including where they grow to maturity, or how and when they move between regions. That has made devising effective conservation efforts a problem.
"The only real threat to whale sharks is us," said Schmidt. "To design proper conservation plans, we need to understand the sharks' lifestyle. We can only protect their habitat if we know what habitat they use."
Schmidt credits some countries for closing whale shark fisheries and hopes that efforts such as ecotourism programs, which sometimes include swims with the gentle giants, may prove an attractive economic alternative to fishing.
With the money brought in by well-managed ecotourism programs, Schmidt said, "people in many countries have come to realize that whale sharks are more valuable alive than dead."
The research was funded by UIC and the Shark Research Institute in Princeton, N.J.
Other authors of the report include Marie Levine, executive director of the Shark Research Institute; Mary Ashley, professor of biological sciences at UIC; and Kevin Feldheim, director of the Pritzker Laboratory at the Field Museum in Chicago.
Journal reference:
Jennifer V. Schmidt, Claudia L. Schmidt, Fusun Ozer, Robin E. Ernst, Kevin A. Feldheim, Mary V. Ashley, Marie Levine. Low Genetic Differentiation across Three Major Ocean Populations of the Whale Shark, Rhincodon typus. PLoS ONE, 2009; 4 (4): e4988 DOI: 10.1371/journal.pone.0004988
Adapted from materials provided by University of Illinois at Chicago.

Why Animals Migrate: New Understandings

New UnderstandingsFor the first time, MIT engineers and colleagues have observed the initiation of a mass gathering and subsequent migration of hundreds of millions of animals — in this case, fish.The work, conducted using a novel imaging technique, "provides information essential to the conservation of marine ecosystems that vast oceanic fish shoals inhabit," the team writes in the March 27 issue of Science.It also confirms theories about the behavior of large groups of animals in general, from bird flocks to locust swarms. Until now those theories had only been predicted through theoretical investigations, computer simulations and laboratory experiments.For example, the team found that once a group of fish reaches a critical population density, it triggers a kind of chain reaction resulting in the synchronized movement of millions of individuals over a large area. The phenomenon is akin to a human "wave" moving around a sports stadium."As far as we know, this is the first time we've quantified this behavior in nature and over such a huge ecosystem," said Nicholas C. Makris '83, PhD '91, leader of the work and a professor of mechanical and ocean engineering. The resulting shoals of migrating fish can extend some 40 kilometers or approximately 25 miles across the ocean.Makris' principal collaborators on the work include Purnima Ratilal PhD '02, a professor at Northeastern University, J. Michael Jech of the Northeast Fisheries Science Center, and Olav Rune Godoe of the Institute of Marine Research in Norway. Other collaborators are from MIT, Northeastern and the Southeast Fisheries Science Center.Off Georges BankThe researchers focused on Atlantic herring off Georges Bank near Boston during the fall spawning season. They found that the formation and movement of large shoals of the fish constituted a kind of daily evening commute to the shallower waters of the bank where they spawn under cover of darkness. Come morning, the fish head back to deeper water and disband.The work was conducted using Ocean Acoustic Waveguide Remote Sensing (OAWRS). In 2006, Makris and colleagues published a paper in Science introducing OAWRS, which they invented, and initial observations made with it.OAWRS allows the team to take images of an area some 100 kilometers (approximately 62 miles) in diameter every 75 seconds. This is a vast improvement over conventional techniques such as fish-finding echo-sounders, which Makris compares to "watching one pixel on a movie screen" while the new technology allows you to "see the entire movie."Both OAWRS and conventional methods rely on acoustics to locate objects by bouncing sound waves off of them. With conventional techniques, survey vessels send high-frequency sound beams into the ocean. In contrast, the new system uses much lower frequency sound that can travel much greater distances and still return useful information with signals far less intense.Toward conservationMakris sees potential in using OAWRS to better monitor — and conserve — fish populations. Large oceanic fish shoals provide vital links in the ocean and human food chain, he explained, but their sheer size makes it difficult to collect information using conventional methods.Ron O'Dor, co-senior scientist of the Census of Marine Life (CoML), commented that "OAWRS allows us to gather information such as geographical distributions, abundance and behavior of fish shoals and to better understand what constitutes healthy fish populations ... which can be implemented by policymakers to better monitor and improve conservation of fish stocks."CoML is an international scientific collaboration engaged in a 10-year initiative to assess and explain the diversity, distribution and abundance of marine life in the oceans. It aims to release the first Census of Marine Life in 2010.Could OAWRS be exploited to find and take more fish, rather than conserve them? Makris believes that it would be virtually impossible. For example, he said, it cannot be used in stealth. "Thieves do not like to work in broad daylight or with the lights on, and OAWRS [essentially] turns the lights on in the ocean making it possible for everyone to see what is happening there and do something about it." He also emphasized that permission from each government would be needed to use it in any nation's territorial waters or in internationally regulated waters.The work was sponsored by the National Oceanographic Partnership Program, the Office of Naval Research, and the Alfred P. Sloan Foundation, and is a contribution to the Census of Marine Life.Source: Massachusetts Institute of Technology

Journey Of A Green Turtle From Indonesia Into Australian Opens Mystery Of 'Oceanic Superhighway'

The remarkable journey of a green turtle from Indonesia into Australian waters is helping conservationists to track the migratory route of this species to the Kimberley-Pilbara coast - one of the few relatively pristine coastal areas left on Earth.

Ana, a female green turtle, was tagged in Indonesia in November as part of a turtle tracking project by WWF and Udayana University in Bali, Indonesia, and has slowly made her way from a nesting beach in East Java, across the Indian Ocean, and is on track for the beaches of the Kimberley in Western Australia.
Her journey, monitored online by WWF, demonstrates the strong biological ties between Indonesia and the reefs on the west Australian coast.
“Ana’s journey is unique. She has revealed an ‘oceanic superhighway’ that helps us better understand how marine turtles navigate around the world’s oceans as well as highlighting the strong ecological and evolutionary connections between Indonesia and Australia’s Kimberley-Pilbara coast,” said Gilly Llewellyn, WWF Ocean’s Program Leader.
“This new finding throws the spotlight on the true natural values of the magnificent Kimberley marine ecosystem and its link to the Coral Triangle to the north – the world’s epicentre of marine biodiversity and the cross-roads of migration routes and breeding grounds for whales, turtles, dolphins and other precious marine species.”
The Coral Triangle spans Indonesia, Malaysia, Philippines, Solomon Islands and Timor Leste, and contains critical habitat for six of the world’s seven species of marine turtles, including green, hawksbill, olive ridley, leatherback, loggerhead and flatback turtles.
All of these species are threatened with extinction as a result of pollution, long-line and trawl fishing that results in the accidental catch of marine turtles, and an illegal trade in turtle eggs, meat, shells and skin.
“The tropical seas of the Coral Triangle have global significance. Decision makers need to keep this in mind when weighing up the need to protect it - and the millions of marine livelihoods that depend on coral reefs across the regions."
WWF’s Coral Triangle Program is currently working to ensure the health of the region's wildlife in the face of human threats in the Indian and Pacific oceans that include long-line and trawl fishing and pollution.
WWF’s marine conservation efforts in the region include the development of a network of Marine Protected Areas (MPAs) to protect and conserve marine wildlife, and to ensure that all fishing is carried out in a sustainable manner. This includes reducing marine animal bycatch, specifically that of turtles, by fishing operations in the Indo Pacific.
“Worldwide, hundreds of thousands of marine turtles are caught annually in the hooks, lines and nets of fishing operations, while on land their nesting beaches are increasingly under threat from industrial development, human disturbance and climate change.
"Ana’s journey has shown us areas where we need to focus our efforts. We need to tap into the secret lives of species such as turtles, so we can design networks of marine protected areas that conserve the full range of plant and animal life, and ensure their longevity for years to come.”
Adapted from materials provided by World Wildlife Fund.

Atlantic Tuna Return Thousands Of Miles To Birthplace To Spawn

Scientists have found new migratory patterns for Mediterranean and western Atlantic bluefin tuna. The Atlantic bluefin tuna is the largest and most sought-after of all tunas, weighing as much as 1,400 pounds and capable of fetching as much as $50,000 or more in Asian markets where its meat is a prized commodity, one big reason why its numbers have declined precipitously since the 1970s.

New research findings reported in Science have critical implications for how bluefin tuna are managed on both sides of the Atlantic Ocean.
A team of international researchers led by Dr. Jay Rooker of Texas A&M University at Galveston adds a new chapter to this emerging story, providing critical insights into the population structure and mixing of North American and Mediterranean populations of bluefin tuna. This comes at an important time as new assessments by international scientists suggest that both western and eastern fisheries are unsustainable at their current levels.
In the current study, Rooker and fellow researchers examine the chemical composition of the fish's ear bone — the otolith — to identify individuals from different nurseries. Chemical signatures in the form of stable carbon and oxygen isotope ratios served as a "birth certificate" and were used by the researchers to determine the origin of adolescent and adult bluefin tuna (2-20 years of age or more) on spawning and foraging grounds in the Atlantic Ocean.
The study shows that trans-Atlantic movement and mixing of populations was high with over half of the juveniles collected in North American waters being of Mediterranean origin. "North American fisheries for juvenile bluefin tuna appear to be supported to a large degree by the Mediterranean population, and thus the condition of this population will directly impact recreational fisheries for bluefin tuna in U.S. waters," according to Rooker.
"Our data coupled with archival tagging data clearly show that the migratory patterns of bluefin tuna are more complex than previously assumed and information on mixing must be included in future assessments to ensure that rebuilding efforts are successful."
Despite the high level of mixing, the team also observed that over 95 percent of adult bluefin tuna returned to their place of origin in either the Gulf of Mexico or Mediterranean Sea to spawn.
"Rates of homing reported here are extremely high and comparable to Pacific salmon, which are known to return to the streams in which they were initially spawned, with very high frequency," according to co-author Barbara Block from Stanford University.
"The new otolith chemistry findings fit perfectly with previous electronic tagging and recent genetic data, which show that distinct bluefin tuna populations mix across the foraging zones of the North Atlantic but separate into distinct spawning areas. This has important implications for the assessment of the western Atlantic bluefin tuna population. To know exactly how many of this smaller population remain, we have to account for this mixing."
Commercially harvested bluefin tuna (commonly called "giants" and weighing over 300 pounds) in New England and Canada were found to be nearly entirely of Gulf of Mexico origin. Results demonstrate that Northern Canadian waters may represent critical foraging habitat of the smaller, more vulnerable population that spawns in the Gulf of Mexico.
In addition to Rooker and Block, David Secor of the University of Maryland Center for Environmental Science; Gregoria DeMetrio of the University of Bari (Italy); Ryan Schlosser of Texas A&M University at Galveston; and John Neilson of the St. Andrews Biological Station co-authored the article. The research was supported by the National Oceanic and Atmospheric Administration's Southeast Fisheries Science Center, the Tag-A-Giant Foundation and the Monterey Bay Aquarium Foundation.
Journal reference:
. Natal Homing and Connectivity in Atlantic Bluefin Tuna Populations. Science, October 3, 2008

Researchers find that tuna swim across Atlantic

Bluefin tuna from both sides of the Atlantic get together as juveniles, a discovery that could affect how the tuna fishery is managed. While North American and Mediterranean bluefin return home to spawn, a study published in Friday's edition of the journal Science reveals that as youngsters the fish travel long distances to intermix. The researchers found that while the largest tuna — sought by commercial fishermen off North America — tend to be local fish, the smaller ones caught by sport fishermen often have originated in the Mediterranean.The team, led by Jay Rooker of Texas A&M University and David Secor of the University of Maryland Center for Environmental Science, was able to identify the origins of fish by examining the chemical composition of the otolith, or ear stone, of the tuna."Juveniles are not conforming to the principal premise of how they've been managed — that fish keep to their own side of the Atlantic," Secor said in a statement. "This could be particularly troubling if North American juveniles head to the Mediterranean. High exploitation there might mean that few make it back. Evaluating where Mediterranean juveniles originate should be our next highest priority."The International Commission for the Conservation of Atlantic Tunas meets next month in Morocco to discuss declining tuna stocks and ways to better manage species.

Leatherback Sea Turtles Followed On 12,700 Mile Migratory Journey Across The Pacific

NOAA researchers and their international partners in Indonesia, Papua New Guinea, and the Solomon Islands are using satellite transmitter technology to track the endangered leatherback sea turtle across the Pacific Ocean। Transmitters attached to the carapace of the turtle send signals to satellites providing researchers with information on the animals' geographic location, diving behavior, and sea temperatures.

Recently, a female leatherback sea turtle was tracked for 647 days and 12,744 miles during its journey from a nesting beach of Papua, Indonesia to its foraging area off the Pacific coast of the United States of America.
This international collaborative effort allows researchers to learn what migratory routes and foraging habitat are used by these endangered ambassadors of the sea. Understanding sea turtles' movements is critical to understanding what habitat is important for their survival and recovery and ensuring their protection as they pass through multiple nation's territories and international waters.
Leatherback populations face threats from egg harvesting, fishery bycatch, ingestion of debris, direct harvest, and habitat loss. Satellite tracking technology is one tool allowing NOAA researchers to unlock secrets of the incredible journeys of this species, allowing us to better understand where they go, what threats they might face at sea, and what management efforts will be required to ensure this species' survival. The new technology can be used in all the world's oceans and is being used for other sea turtle and non-sea turtle species research.
Adapted from materials provided by National Oceanic And Atmospheric Administration, via EurekAlert!, a service of AAAS.

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.

Japan launch 'prince fish' catch-and-eat drive

Authorities around Japan's largest lake have launched a "catch-and-eat" drive to eliminate the bluegill as the emperor himself voiced regret about introducing the fish. Emperor Akihito, a fish expert, brought the bluegill from the United States a half-century ago when he was crown prince, hoping to offer a new source of food to Japan.But the bluegill, once celebrated as "prince fish," has turned into a nuisance in Japanese rivers and lakes by feeding on native species, leading the emperor to offer unusually personal comments of regret earlier this month.The central province of Shiga has introduced what it calls "catch-and-eat," encouraging people who fish bluegill in Japan's largest Lake Biwa not to release but to eat them.The prefecture's official website has pictures showing how to slice open the fish along with recipes to make bluegill fries and cook them with sweet-and-sour sauce."The fish taste very good," Shiga fisheries official Kunihiko Kuwamura said, adding there was also "bluegill sushi" offered by a private company.Bluegill is common dinner fare in the United States and is the state fish of Illinois, where Chicago's legendary mayor Richard J. Daley offered the fish specimen as a gift to the visiting Akihito in 1960.Akihito voiced regret in a speech at a fisheries event on November 11, saying Lake Biwa's catch had plunged due to foreign-origin fish."I brought bluegill back from the United States nearly 50 years ago and donated them to a research institute of the Fisheries Agency," said Akihito, whose public remarks are usually ceremonial."Its cultivation started as there were great expectations of raising them for food in those days. My heart aches to see it has turned out like this," Akihito said.The Fisheries Agency says its research institute received the fish in 1960 and bred and distributed them around the country.Shiga prefecture denies bluegill escaped its institute's nets. They were first spotted swimming in Lake Biwa in 1965, according to Kuwamura.Kuwamura said the prefecture has tried for years to get rid of foreign-origin fish and that the emperor's remark "is a boon for us.""We will keep pushing ahead," he said.

Small Seabirds Log Longest Animal Migration Ever Recorded

Every summer, millions of sooty shearwaters arrive off the coast of California, their huge flocks astonishing visitors who may have trouble grasping that the dark swirling clouds over the water consist of seabirds। Scientists have long known that sooty shearwaters breed in New Zealand and Chile and migrate to feeding grounds in the Northern Hemisphere. But the details of this remarkable transequatorial migration are only now emerging from a study using electronic tracking tags to follow individual birds.

The flights of sooty shearwaters documented in this new study represent the longest animal migration routes ever recorded using electronic tracking technology: around 65,000 kilometers (39,000 miles). Taking advantage of prevailing winds along different parts of the migration route, the birds trace giant figure eights over the Pacific Basin.
"The only other bird species known that could rival the migrations of the sooty shearwater would be the arctic tern, which breeds in the Arctic and migrates to Antarctica. But we don't know if they do that in a single season, because nobody's ever tracked them," said Scott Shaffer, a research biologist at the University of California, Santa Cruz, and first author of a paper describing the new findings, published in next week's online early edition of Proceedings of the National Academy of Sciences (PNAS).
Shaffer worked with an international team of scientists from UCSC and other institutions in the United States, New Zealand, and France. The researchers found that the migratory cycle of sooty shearwaters encompasses the entire Pacific Basin, focusing on the richest feeding grounds in both hemispheres--from Antarctic waters in the south during the breeding season to bountiful coastal currents off California, Alaska, and Japan in the north. These small seabirds cross the equator twice a year in pursuit of an endless summer in which their feeding areas are always at or near the period of peak productivity.
Diving patterns recorded by the tags indicate the birds stop little if at all to feed as they pass through the equatorial regions on their journey between the Southern and Northern Hemispheres.
"When they cross the equator, they're traveling fast and not stopping much to feed. They feed near Antarctica during the austral summer, then zip north to feed in one of three areas of the North Pacific, taking advantage of high productivity throughout the year," Shaffer said.
Sooty shearwaters are one of the most abundant bird species in the world, with a total population estimated at about 20 million. Nevertheless, they are potentially vulnerable to changes in their food supply, Shaffer said. Scientists have reported recent population declines at breeding colonies in New Zealand and in the eastern North Pacific.
The shearwaters feed on fish, squid, and shrimplike krill, which they take from the surface or pursue underwater. The electronic tags recorded birds diving to depths as great as 68 meters (225 feet) to capture their prey. Average dive depth was about 14 meters (46 feet).
The new study shows that, contrary to previous assumptions, sooty shearwaters do not make a big pan-Pacific sweep to cover all of their feeding areas in the Northern Hemisphere. Instead, individual birds went to just one of the three major hot spots and stayed there until it was time to return south to breed. But Shaffer said the birds that travel to different regions do not represent distinct populations of shearwaters.
"Birds that came to California stayed in California, and if they went to Japan they stayed there and then returned to New Zealand. But two birds from the same nest can end up going to opposite sides of the Pacific, and birds from different breeding colonies can end up in the same place," he said.
The timing and route of the northward migration was somewhat variable, with birds crossing the equator at various locations over a period of about a month. But the return trip was remarkably synchronous, Shaffer said. All of the tagged birds funneled through a narrow corridor and crossed the equator within a ten-day period in October. Ongoing research using tags redeployed on the same birds will show whether or not individual birds have preferred feeding areas that they travel to each year.
The research on sooty shearwaters is part of a Census of Marine Life project called Tagging Of Pacific Pelagics (TOPP), which is deploying electronic tags on 23 species of top predators in the North Pacific Ocean. Daniel Costa, a professor of ecology and evolutionary biology at UCSC who oversees TOPP studies of marine mammals and seabirds, said the shearwater study was only possible because of the increasing miniaturization of electronic tags.
"When we first got together to plan the TOPP program, we didn't know if the technology was available to tag a bird that small," Costa said. "Sooty shearwaters were a species that we knew came here from the Southern Hemisphere, but we knew very little about its migratory patterns. Now we know this is an organism that integrates resources across the entire Pacific, which is quite a feat when you think about it."
The tag used on the sooty shearwaters, made by a Canadian company called Lotek Wireless, weighs about 12 grams (less than half an ounce)। The researchers recaptured 20 tagged birds at two breeding colonies in New Zealand. The tags recorded the daily activities of each bird during part of the breeding season and throughout the migration to the Northern Hemisphere and back. In addition to geographic locations, the tags recorded pressure and temperature data, providing information about the birds' diving behavior and the temperatures they encountered at sea.

The temperature data helped Shaffer's team ensure the accuracy of the location data, using a technique that integrates temperature readings from the animals with those obtained by orbiting satellites. This method was developed in the lab of TOPP principal investigator Barbara Block of Stanford University and validated by Shaffer's team in studies of albatrosses.
Collaborators on the project also included seabird expert and TOPP investigator Henri Weimerskirch of the French National Center for Scientific Research (CNRS). He persuaded researchers in New Zealand who have been studying the shearwater breeding colonies to join forces with the TOPP researchers.
"One of the nice things about TOPP is that we have a consortium of some of the top scientists in the world, which makes it easy to make those kinds of connections," Costa said.
In addition to Shaffer, Costa, Block, and Weimerskirch, the coauthors on the PNAS paper include Yann Tremblay, a postdoctoral researcher at UCSC; Darren Scott and Henrik Moller of the University of Otago, New Zealand; David Thompson and Paul Sagar of the National Institute of Water and Atmospheric Research, New Zealand; Graeme Taylor of the Department of Conservation, New Zealand; and David Foley of the University of Hawaii.
Support for the sooty shearwater study was provided by the Gordon and Betty Moore Foundation, the David and Lucile Packard Foundation, and the National Science Foundation.
More information about the study, including multimedia content, will be available at the TOPP program's award-winning web site at http://www.eurekalert.org/.
Adapted from materials provided by University of California - Santa Cruz.