Chapman D.D.,Marine Conservation Institute |
Feldheim K.A.,Pritzker Laboratory for Molecular Systematics and Evolution |
Papastamatiou Y.P.,University of St. Andrews |
Hueter R.E.,Center for Shark Research
Annual Review of Marine Science | Year: 2015
The overexploitation of sharks has become a global environmental issue in need of a comprehensive and multifaceted management response. Tracking studies are beginning to elucidate how shark movements shape the internal dynamics and structure of populations, which determine the most appropriate scale of these management efforts. Tracked sharks frequently either remain in a restricted geographic area for an extended period of time (residency) or return to a previously resided-in area after making long-distance movements (site fidelity). Genetic studies have shown that some individuals of certain species preferentially return to their exact birthplaces (natal philopatry) or birth regions (regional philopatry) for either parturition or mating, even though they make long-distance movements that would allow them to breed elsewhere. More than 80 peer-reviewed articles, constituting the majority of published shark tracking and population genetic studies, provide evidence of at least one of these behaviors in a combined 31 shark species from six of the eight extant orders. Residency, site fidelity, and philopatry can alone or in combination structure many coastal shark populations on finer geographic scales than expected based on their potential for dispersal. This information should therefore be used to scale and inform assessment, management, and conservation activities intended to restore depleted shark populations. Copyright © 2015 by Annual Reviews. All rights reserved.
Gelsleichter J.,Center for Shark Research |
Szabo N.J.,University of Florida
Science of the Total Environment | Year: 2013
The presence of human pharmaceuticals in sewage-impacted ecosystems is a growing concern that poses health risks to aquatic wildlife. Despite this, few studies have investigated the uptake of active pharmaceutical ingredients (APIs) in aquatic organisms. In this study, the uptake of 9 APIs from human drugs was examined and compared in neonate bull sharks (Carcharhinus leucas) residing in pristine (Myakka River) and wastewater-impacted (Caloosahatchee River) tributaries of Florida's Charlotte Harbor estuary. The synthetic estrogen used in human contraceptives (17α-ethynylestradiol) and 6 of the selective serotonin/norepinephrine reuptake inhibitors (citalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, venlafaxine) used in human antidepressants were observed at detectable and, in some cases, quantifiable levels in plasma of Caloosahatchee River sharks. Comparatively, only venlafaxine was detected in the plasma of a single Myakka River shark at a level below the limit of quantitation. These results suggest that sharks residing in wastewater-impacted habitats accumulate APIs, a factor that may pose special risks to C. leucas since it is one of few shark species to regularly occupy freshwater systems. Further research is needed to determine if the low levels of API uptake observed in Caloosahatchee River bull sharks pose health risks to these animals. © 2013 Elsevier B.V.
Gardiner J.M.,University of South Florida |
Gardiner J.M.,Center for Shark Research |
Atema J.,Boston University |
Atema J.,National Oceanic and Atmospheric Administration |
Atema J.,Woods Hole Oceanographic Institution
Current Biology | Year: 2010
The direction of an odor signal source can be estimated from bilateral differences in signal intensity and/or arrival time. The best-known examples of the use of arrival time differences are in acoustic orientation . For chemoreception, animals are believed to orient by comparing bilateral odor concentration differences, turning toward higher concentrations [2-4]. However, time differences should not be ignored, because odor plumes show chaotic intermittency, with the concentration variance several orders of magnitude greater than the concentration mean (e.g., ). We presented a small shark species, Mustelus canis, with carefully timed and measured odor pulses directly into their nares. They turned toward the side stimulated first, even with delayed pulses of higher concentration. This is the first conclusive evidence that under seminatural conditions and without training, bilateral time differences trump odor concentration differences. This response would steer the shark into an odor patch each time and thereby enhance its contact with the plume, i.e., a stream of patches. Animals with more widely spaced nares would be able to resolve smaller angles of attack at higher swimming speeds, a feature that may have contributed to the evolution of hammerhead sharks. This constitutes a novel steering algorithm for tracking odor plumes. © 2010 Elsevier Ltd.
Cuba is surrounded by sharks. Fishermen catch them, residents eat them and, increasingly, tourists are coming to see them. Now the island nation is gearing up to manage them, and its efforts are bolstering a nascent environmental partnership with the United States. “It’s a big step forward for Cuba and the region,” says Jorge Angulo-Valdés, head of the Marine Conservation Group at the University of Havana’s Center for Marine Research and a visiting professor at the University of Florida in Gainesville. “It’s time for us to get together, identify common goals in resource management and make them work.” On 21 October, Cuba plans to release a management plan that will lay the groundwork for research and, eventually, regulations to protect extensive but largely undocumented shark and ray populations. Roughly half of the 100 species of shark resident in the Caribbean Sea and Gulf of Mexico have been seen in Cuban waters, including some — such as the whitetip (Carcharhinus longimanus) and longfin mako (Isurus paucus) — that have experienced sharp declines elsewhere. The Cuban government has consulted with environmentalists and academics from the United States and other countries in developing the plan. “Cuba is a kind of biodiversity epicentre for sharks,” says Robert Hueter, director of the Center for Shark Research at the Mote Marine Laboratory and Aquarium in Sarasota, Florida, who is one of those working with the Cuban scientists. “The science is not at a level yet to do rigorous stock estimates, but we are moving in that direction with this plan.” Most of what is known about Cuba’s shark populations has come from the fishing industry, which often captures sharks as by-products of its regular operations. The Cuban government has already established marine protected areas along 20% of its coastline and is planning to expand that network within the 70,000 square kilometres of its coastal fishery. It has also begun to regulate the equipment used in fishing, and is looking to establish catch limits for various fish species, including sharks. Both US and Cuban scientists say that the collaboration is helping to pave the way for more formal cooperation now that the two cold-war foes have re-established political relations. In April, the US National Oceanic and Atmospheric Administration (NOAA) sent a research vessel on a cruise around the island with Cuban scientists. And on 5 October, US secretary of state John Kerry and Cuban officials announced at an oceans conference in Chile that the two nations were finalizing plans to cooperate on research, education and management in marine protected areas. The agreement could be finalized as early as next month, says Billy Causey, regional director for NOAA’s Office of National Marine Sanctuaries in Key West, Florida. US environmentalists began pushing the idea of cooperation with Cuba on marine conservation after the 2008 election of President Barack Obama, who pledged during the campaign to engage with Cuba. The first signs of real progress came in September 2009, says Daniel Whittle, who heads the Cuba programme for the Environmental Defense Fund (EDF), an environmental group based in New York City. Then, the United States allowed four Cuban scientists, three of whom were marine and coastal researchers, to attend a series of meetings in the country. And in November last year, Angulo-Valdés was part of a cadre of Cuban scientists that visited the state department and several members of Congress. A month later, Obama ordered the restoration of diplomatic ties with Cuba. “It’s slowly beginning to change,” says Whittle, referring to links between the nations. “That’s why the announcement in Chile was so significant: finally the two governments publicly acknowledged that they are in fact working directly together on environmental issues.” The EDF and other conservation groups have been trying to build cooperation between Cuba, Mexico and the United States within the Gulf of Mexico. NOAA’s April cruise, which focused on tallying the larvae of bluefin tuna (Thunnus thynnus) in Cuban and Mexican waters, marked the first formal government engagement on that front since Obama’s December announcement, Causey says. The main question facing the shark-management plan is whether the Cuban government will be able to mobilize enough money to implement it. The EDF and other groups have been raising funds to pay for some of the initial work on the plan, including training fishing crews to identify and report the sharks that they catch. But scientists need to conduct population surveys that are independent of those done by commercial fisheries, and Cuban research institutions are already stretched thin. The country has only two operational research vessels, and scarce resources to equip and operate them. The kind of tags needed to track shark movements through satellites can cost US$2,500 each. So far, Cuba has tagged just four sharks with such devices. “We have to see how the government implements the plan, and how they get around the funding problem,” Angulo-Valdés says. “It’s going to be a challenge.”
Simpfendorfer C.A.,Center for Shark Research |
Wiley T.R.,Center for Shark Research |
Wiley T.R.,Texas Parks and Wildlife Department |
Yeiser B.G.,Center for Shark Research
Biological Conservation | Year: 2010
Understanding the movement and habitat use patterns of threatened species is essential to effective conservation planning. Modern tracking techniques such as active tracking and passive acoustic monitoring can be useful tools in elucidating this information for aquatic species. To aid in the development of conservation strategies for juvenile critically endangered smalltooth sawfish (Pristis pectinata) their fine scale movements and habitat use in southwest Florida were studied using a combination of these techniques. Between 2002 and 2006 a total of 12 individuals were actively tracked for periods of up to 24. h to provide detailed habitat use and movement parameters (distance moved, speed, and linearity). Smaller individuals (<100. cm stretched total length (STL)) had the smallest home ranges, low linearity of movement and had a preference for very shallow mud banks. Juveniles >100. cm STL demonstrated larger home ranges, preference for shallow mud or and sand banks, and remained close to mangrove shorelines. Tide was found to be the main factor influencing movement on short time scales. Sawfish <150. cm STL spend the majority of their time in water <50. cm, while larger juveniles spend most of their time in water 50-100. cm deep. From 2003 to 2007 a total of 22 individuals were fitted with acoustic tags for long-term monitoring. Juveniles >130. cm had high levels of site fidelity for specific nursery areas for periods up to almost 3. months, but the smaller juveniles had relatively short site fidelity to specific locations. The use of a combination of tracking and monitoring techniques provided an expanded range of information by generating both short and long term data on habitat use. The data demonstrated that the conservation of shallow mud and sand banks, and mangrove shorelines will benefit the recovery of these endangered elasmobranchs. © 2010 Elsevier Ltd.