Browsing by Author "Walker, Alan"
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- First direct evidence of adult European eels migrating to their breeding place in the Sargasso SeaPublication . Wright, Rosalind M.; Piper, Adam T.; Aarestrup, Kim; Azevedo, José M. N.; Cowan, George; Don, Andy; Gollock, Matthew; Rodriguez Ramallo, Sara; Velterop, Randolph; Walker, Alan; Westerberg, Håkan; Righton, DavidThe European eel (Anguilla anguilla) is critically endangered (according to the most recent IUCN assessment) and has suffered a 95% decline in recruitment since the 1980s, attributed in part to factors occurring during the marine phases of its life-cycle. As an adult, the European eel undertakes the longest spawning migration of all anguillid eels, a distance of 5000 to 10,000 km across the Atlantic Ocean to the Sargasso Sea. However, despite the passage of almost 100 years since Johannes Schmidt proposed the Sargasso Sea as the breeding place of European eels on the basis of larval surveys, no eggs or spawning adults have ever been sampled there to confirm this. Fundamental questions therefore remain about the oceanic migration of adult eels, including navigation mechanisms, the routes taken, timings of arrival, swimming speed and spawning locations. We attached satellite tags to 26 eels from rivers in the Azores archipelago and tracked them for periods between 40 and 366 days at speeds between 3 and 12 km day−1, and provide the first direct evidence of adult European eels reaching their presumed breeding place in the Sargasso Sea.
- Testing a global standard for quantifying species recovery and assessing conservation impactPublication . Grace, Molly K.; Akçakaya, H. Resit; Bennett, Elizabeth L.; Brooks, Thomas M.; Heath, Anna; Hedges, Simon; Hilton‐Taylor, Craig; Hoffmann, Michael; Hochkirch, Axel; Jenkins, Richard; Keith, David A.; Elangovan, Vanitha; Fairclough, David; Febbraro, Mirko Di; Fenu, Giuseppe; Fernandes, Fernando Moreira; Fernandez, Eduardo Pinheiro; Finucci, Brittany; Földesi, Rita; Jorgensen, Dennis; Gupta, Garima; Ryan, Catherine; Foley, Catherine M.; Ford, Matthew; Forstner, Michael R. J.; García, Néstor; Garcia‐Sandoval, Ricardo; Gardner, Penny C.; Garibay‐Orijel, Roberto; Gatan‐Balbas, Marites; Gauto, Irene; Ghazi, Mirza Ghazanfar Ullah; Mitcheson, Yvonne J. Sadovy; Katsis, Lydia K. D.; Katdare, Suyash; Godfrey, Stephanie S.; Talukdar, Bibhab Kumar; Hagen, Christina; Hagen, Christian A.; Hall, Madison B.; Hallerman, Eric; Hare, Kelly; Hart, Tom; Salmon, Lily; Hartdegen, Ruston; Harvey‐Brown, Yvette; Hatfield, Richard; Hawke, Tahneal; Tatayah, Vikash; Kaul, Rahul; Hermes, Claudia; Hitchmough, Rod; Long, Barney; Kaunda‐Arara, Boaz; Salvador, Carlos Henrique; Keith‐Diagne, Lucy; Kraus, Daniel T.; Lima, Thales Moreira; Lindeman, Ken; Linsky, Jean; Thomas, Philip; Louis, Edward; Loy, Anna; Lughadha, Eimear Nic; Mangel, Jeffrey C.; Samways, Michael J.; Mallon, David P.; Marinari, Paul E.; Martin, Gabriel M.; Martinelli, Gustavo; McGowan, Philip J. K.; McInnes, Alistair; Tringali, Angela; Teles Barbosa Mendes, Eduardo; Millard, Michael J.; Mirande, Claire; Sanjuan, Tatiana; Money, Daniel; Monks, Joanne M.; Meijaard, Erik; Morales, Carolina Laura; Mumu, Nazia Naoreen; Negrao, Raquel; Nguyen, Anh Ha; Trinh‐Dinh, Hoang; Niloy, Md. Nazmul Hasan; Norbury, Grant Leslie; Souza dos Santos, Amanda; Nordmeyer, Cale; Norris, Darren; O'Brien, Mark; Oda, Gabriela Akemi; Milner‐Gulland, E. J.; Orsenigo, Simone; Outerbridge, Mark Evan; Pasachnik, Stesha; Tuboi, Chongpi; Pérez‐Jiménez, Juan Carlos; Sasaki, Hiroshi; Pike, Charlotte; Pilkington, Fred; Plumb, Glenn; Portela, Rita de Cassia Quitete; Prohaska, Ana; Quintana, Manuel G.; Rodriguez, Jon Paul; Rakotondrasoa, Eddie Fanantenana; Ranglack, Dustin H.; Usmani, Aftab Alam; Stuart, Simon N.; Rankou, Hassan; Rawat, Ajay Prakash; Reardon, James Thomas; Rheingantz, Marcelo Lopes; Richter, Stephen C.; Rivers, Malin C.; Rogers, Luke Rollie; Rosa, Patrícia da; Stephenson, P. J.; Rose, Paul; Vié, Jean‐Christophe; Vasco‐Palacios, Aída M.; Royer, Emily; Gollock, Matthew; Schutz, Emmanuel; Scott, Heather Ann; Scott, Robert Michael; Serena, Fabrizio; Sharma, Surya P.; Shuey, John A.; Silva, Carlos Julio Polo; Simaika, John P.; Smith, David R.; Spaet, Julia L.Y.; González, Benito A.; Acebes, Pablo; Young, Richard P.; Sultana, Shanjida; Hoffmann, Pablo Melo; Virens, Jo; Walker, Alan; Wallace, Bryan; Waller, Lauren J.; Wang, Hongfeng; Wearn, Oliver R.; Grant, Tandora D.; Weerd, Merlijn; Weigmann, Simon; Willcox, Daniel; Woinarski, John; Howarth, Charlie; Alfaro‐Shigueto, Joanna; Yong, Jean W.H.; Young, Stuart; Alvarez‐Clare, Silvia; Andriantsimanarilafy, Raphali Rodlis; Gray, Thomas; Arbetman, Marina; Azat, Claudio; Bacchetta, Gianluigi; Badola, Ruchi; Barcelos, Luis M. D.; Hudson, Michael A.; Barreiros, João P.; Basak, Sayanti; Berger, Danielle J.; Bhattacharyya, Sabuj; Gregory, Andrew J.; Bino, Gilad; Borges, Paulo A. V.; Boughton, Raoul K.; Brockmann, H. Jane; Buckley, Hannah L.; Burfield, Ian J.; Hussain, Syed Ainul; Burton, James; Camacho‐Badani, Teresa; Cano‐Alonso, Luis Santiago; Grunsven, Roy H.A.; Carmichael, Ruth H.; Carrero, Christina; Carroll, John P.; Catsadorakis, Giorgos; Chapple, David G.; Chapron, Guillaume; Chowdhury, Gawsia Wahidunnessa; Huveneers, Charlie; Claassens, Louw; Cogoni, Donatella; Gryzenhout, Marieka; Constantine, Rochelle; Craig, Christie Anne; Cunningham, Andrew A.; Dahal, Nishma; Daltry, Jennifer C.; Das, Goura Chandra; Dasgupta, Niladri; Davey, Alexandra; Jacques, Hélène; Davies, Katharine; Guernsey, Noelle C.; Develey, PedroRecognizing the imperative to evaluate species recovery and conservation impact, in 2012 the International Union for Conservation of Nature (IUCN) called for development of a "Green List of Species" (now the IUCN Green Status of Species). A draft Green Status framework for assessing species' progress toward recovery, published in 2018, proposed 2 separate but interlinked components: a standardized method (i.e., measurement against benchmarks of species' viability, functionality, and preimpact distribution) to determine current species recovery status (herein species recovery score) and application of that method to estimate past and potential future impacts of conservation based on 4 metrics (conservation legacy, conservation dependence, conservation gain, and recovery potential). We tested the framework with 181 species representing diverse taxa, life histories, biomes, and IUCN Red List categories (extinction risk). Based on the observed distribution of species' recovery scores, we propose the following species recovery categories: fully recovered, slightly depleted, moderately depleted, largely depleted, critically depleted, extinct in the wild, and indeterminate. Fifty-nine percent of tested species were considered largely or critically depleted. Although there was a negative relationship between extinction risk and species recovery score, variation was considerable. Some species in lower risk categories were assessed as farther from recovery than those at higher risk. This emphasizes that species recovery is conceptually different from extinction risk and reinforces the utility of the IUCN Green Status of Species to more fully understand species conservation status. Although extinction risk did not predict conservation legacy, conservation dependence, or conservation gain, it was positively correlated with recovery potential. Only 1.7% of tested species were categorized as zero across all 4 of these conservation impact metrics, indicating that conservation has, or will, play a role in improving or maintaining species status for the vast majority of these species. Based on our results, we devised an updated assessment framework that introduces the option of using a dynamic baseline to assess future impacts of conservation over the short term to avoid misleading results which were generated in a small number of cases, and redefines short term as 10 years to better align with conservation planning. These changes are reflected in the IUCN Green Status of Species Standard.