Understanding and predicting animal movement is important as it is central to establishing effective management and conservation strategies . Until relatively recently, studying the movements and behaviors of highly migratory marine species (turtles, sharks, whales, penguins, seals and billfish) have been challenging due to the logistical and technological constraints of working in aquatic environments. However, rapid advancements in electronic tagging and tracking tools have significantly improved the ability of scientists to remotely study the movements of these enigmatic, and often threatened, animals [2,3].
Recently, Dan Costa and colleagues  summarized new insights in the migrations of large pelagic marine animals arising through the use of electronic tagging (acoustic and satellite telemetry). The paper reviewed how electronic tagging has significantly increased our understanding of their movements over scales ranging from < 10 m to > 5000 km (e.g. turtles, albatrosses, tunas, sharks, and over long time periods (years). Further, Costa and colleagues  reviewed how tagging studies are permitting scientists to understand how movements and habitat use are influenced by environmental (e.g. temperature, chlorophyll) and biological variables (e.g. prey availability) [5,6]. The paper also discussed how electronic tagging been used to establish and evaluate effective conservation strategies for highly migratory marine species; for example, identifying critical habitats of sea turtles for implementing marine protected areas .
Despite these advances and benefits of tagging research, there still remains some areas for improvement. Costa and team suggest that technological research priorities should include improved tag powering mechanisms, increased sensor capabilities, better attachment techniques, tag miniaturization and more efficient data recovery methods.
Emerging analytical tools and technologies capable of measuring the physiological state, movement capacity, and performance ability of marine animals, as well as the environmental factors they encounter, are allowing researchers to increasingly understand and predict why animals move [4, 11-14] (Figure below). As this field continues to advance, electronic tagging will enable scientists to address some of the most pressing environmental issues of the 21st century, including: (1) how will marine species be impacted by human-induced global change (e.g. warming climate, habitat loss)? (2) What is the adaptive capacity of these species to cope with a changing planet? (3) What will be the associated ecological and evolutionary consequences? (4) if and what strategies can be taken to reduce potential changes and foster conservation of marine species. As tracking tools continue to evolve with advances in technology and research, so will its application for understanding, predicting and responding to the ecological, evolutionary and conservation implications of marine animal movement.
Our Tagging Research
My laboratory at the University of Miami is currently using satellite tags to track the movements of shark species in the subtropical Atlantic Ocean. The goal of this work is to understand the migratory routes and residency patterns of these sharks to identify “hot spots” in place and time that are critical for mating, giving birth and feeding as well as locations where these animals are vulnerable to destructive fishing. By characterizing and identifying these hot spots, we can help supply policy makers with the data they need to implement effective management strategies that will improve conservation for these species. For example, our research has revealed that a great hammerhead tagged in the Florida Keys migrated up the east coast of the United States, as far north as New Jersey before moving offshore. This represented a range extension for this species as they had never been documented as far north. Another of our tagging research focusing on tiger sharks that are fed at a popular ecotourism dive site in the Bahamas, found that the dive tourism did not impact the long-term, large-scale movements of the tiger sharks (Check out a video summary here). Moreover, the tiger sharks tracked made extensive migrations thousands of kms out in the middle of the Atlantic Ocean on foraging forays (see map below). Our tracking of bull sharks and tarpon in the Florida Keys revealed that both the sharks and tarpon swam through similar areas, but that tarpon altered their movements in areas frequented by bull sharks to avoid chances of being attacked. In fact, tarpon appeared to even forfeit the best feeding sites to minimize their risk of predation from bull sharks. You can track the movements of our tagged sharks through an interactive google earth map on our website.
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- B. A. Block et al., Tracking apex marine predator movements in a dynamic ocean., Nature 475, 86–90 (2011).
- T. W. Horton et al., Straight as an arrow: humpback whales swim constant course tracks during long-distance migration., Biol. Lett. 7, 674–679 (2011).
- B. A. Wallace et al., Global Conservation Priorities for Marine Turtles, PLoS One (2011).
- G. C. Hays, C. J. A. Bradshaw, M. C. James, P. Lovell, D. W. Sims, Why do Argos satellite tags deployed on marine animals stop transmitting?, J. Exp. Mar. Bio. Ecol. 349, 52–60 (2007).
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- C. Clark, C. Forney, E. Manii, Tracking and Following a Tagged Leopard Shark with an Autonomous Underwater Vehicle, J. Field. Robot. 30, 309–322 (2013).
- S. Cooke, S. et al., Developing a mechanistic understanding of fish migrations by linking telemetry with physiology, behavior, genomics and experimental biology: an interdisciplinary, Fisheries , 321–339 (2008).
- N. E. Humphries, H. Weimerskirch, N. Queiroz, E. J. Southall, D. W. Sims, Foraging success of biological Lévy flights recorded in situ., Proc. Natl. Acad. Sci. U. S. A. 109, 7169–74 (2012).
- B. A. Block et al., Tracking apex marine predator movements in a dynamic ocean, Nature 475, 86–90 (2011).
- K. M. Miller et al., Genomic signatures predict migration and spawning failure in wild Canadian salmon., Science 331, 214–217 (2011).
Attempts to maintain biodiversity in the world’s oceans could be targeting the wrong areas, with the seas around the UK as important as coral reefs.
That is the findings of a new report by scientists from the universities of Dundee and Portsmouth.
They examined the importance of each species rather than simply counting the number of species in a given area.
They found areas with fewer species, like those around the UK, were more affected by issues like pollution.
The researchers claim the study, published in the journal Nature, challenges conventional wisdom about what biodiversity means.
Professor Terry Dawson, from the University of Dundee, said: “Conventional global conservation priority has focused on tropical sites having high biodiversity richness in terms of species.
“In contrast, our research has shown that to maintain healthy, resilient marine habitats those regions with fewer species, such as found in the seas around the UK for example, may actually be more vulnerable to catastrophic collapse from human pressures such as pollution and overfishing.”
Dr Trevor Willis, from the Institute of Marine Sciences at the University of Portsmouth, added: “Since the days of Darwin and Linnaeus, the number of different species in an ecosystem – what researchers call ‘species richness’ – has dominated the scientific view of global biodiversity patterns and has long been used as a biological basis for management of imperilled ecosystems.
“But just counting species is a very crude way of understanding diversity.
“By gathering information on the animal’s traits – what they eat, how they move, where they live – we can understand more about how they vary in terms of their function in the operation of natural ecosystems.
“This functional variation is really the essence of biodiversity.”
The study was carried out by an international team of researchers from Australia, Chile, Indonesia, Italy, Spain, Sweden, the US and the UK.
They measured factors other than the traditional species count, such as a species’ role in an ecosystem or the number of individuals of a particular species, revealing new hotspots of biodiversity, including some nutrient-rich, temperate waters.
The research team noted how the members of each of these species lived, using a detailed matrix of functional traits.
These included what the species ate (plankton, invertebrates, algae, other fish, or a combination), how they ate it (browsing, scraping, or predation), where they lived (in, on, or near the bottom, attached, or free-swimming), whether they were active at night or during the day, and how gregarious they were (solitary, paired, or schooling).
The information was collected through a “citizen science” initiative developed in Tasmania with recreational scuba divers trained to carry out the surveys.
The researchers then analysed data from 4,357 standardised surveys at 1,844 coral and rocky reef sites worldwide.
The surveys spanned 133 degrees of latitude and found 2,473 species of fish.
The team said the findings had important implications for planning and management, particularly in regards to the marine protected areas (MPAs).
Lead author Dr Rick Stuart-Smith, of the University of Tasmania’s Institute for Marine and Antarctic Studies, said: “Relatively few MPAs are located at temperate latitudes, particularly in the southern hemisphere, a bias accentuated in recent years with global focus on declaration of large tropical MPAs.
“Our results identify further unrecognised biodiversity value in some temperate and southern hemisphere regions, strengthening the argument for greater representation of these areas in global MPA protection.”
Dr Willis added: “We should perhaps be having a harder look at how well higher latitude marine ecosystems – like around the UK – are being represented by no-take MPAs that enable us to see what relatively natural marine ecosystems should look like.”
Credits: BBC Nature
Whales Have Sonar “Beam” for Targeting Prey
Christine Dell’Amore / National Geographic News
Published March 22, 2012
Toothed whales target quickly moving prey with a constantly shifting, tightly focused sonar beam, a new study says.
All toothed whales and dolphins echolocate, clicking loudly via special nasal structures and listening for echoes bouncing off objects. This skill is especially crucial in the dark ocean, where the mammals’ vision is of little use.
New experiments show that whales can focus their clicks into a type of sonar beam to efficiently track fast-moving prey.
“The bottom line is echolocation is how these animals make their living,” said study leader Laura Kloepper, a zoologist at the University of Hawaii in Honululu.
“Not only do they have to locate fish, they have to discriminate fish and figure out what kind of fish it is—it’s this constant underwater dance between predator and prey.
“It makes sense [that] of course there has to be focusing going on.” (See “Killer Whales Target Favorite Fish With Sonar?”)
For their experiments, the team worked with Kina, a false killer whale at the University of Hawaii with decades of training—and a penchant for mischievously splashing Kloepper.
“After a few days I learned to carry an umbrella to protect my equipment,” Kloepper said. Kina “got a kick out of watching me scramble.”
In the first experiment, a trainer instructed Kina to swim into an underwater hoop up to her pectoral fins. Then, a soundproof door lowered and she echolocated on a target—a hollow cylinder that looks like a toilet paper tube.
Kina had previously been trained to recognize the thickness of this particular cylinder and to signal this by touching a button with her snout, which earned her a fish reward.
The whale was also trained to stay still when shown other cylinders of varying thicknesses.
Kloepper and colleagues then presented Kina with two other types of cylinders to test her echolocation skills: one with much thicker walls, which she could detect easily, and another with only slightly thicker walls, which was tougher for her to pinpoint.
Over a period of weeks, the team also randomly changed the distances from which Kina echolocated the cylinders.
Whale Sonar Has Eye-Like Focus
While Kina was echolocating the various targets, an array of underwater microphones were measuring her constant barrage of sonar waves. From this data, the scientists created a statistical algorithm that recreated Kina’s sonar beams.
This revealed that Kina’s beam shape had changed depending on the cylinders’ distances and differences—much as an eye continually refocuses on an object, explained Kloepper, whose study was published recently in the Journal of Experimental Biology.
“It’s remarkable they have this beautiful acoustic lens in their melon,” said study co-author Paul Nachtigall, a zoologist at the University of Hawaii in Honululu.
As recently as 2008, “not much attention was paid to the incredible flexibility” of echolocating whales, noted Dorian Houser, director of Biology and Bioacoustic Research at the National Marine Mammal Foundation, a nonprofit based in San Diego.
The new study contributes “to our growing knowledge about the ability of [the whale] to control its echolocation beam by changing its width and frequency content,” Houser said via email.
Plenty of echolocation mysteries remain, however—for example, how whales can hear properly even while clicking incredibly loudly (the focus of the study team’s next project).
“The more information we obtain on their ability to manipulate the beam,” Houser said, “the more complicated the story becomes.”
Credits: National Geographic