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9 - Current trends in the assessment and management of stocks
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- By Manuel Barange, Miguel Bernal, Maria Cristina Cergole, Luis A. Cubillos, Georgi M. Daskalov, Carryn L. de Moor, José A. A. De Oliveira, Mark Dickey-Collas, Dave J. Gaughan, Kevin Hill, Larry D. Jacobson, Fritz W. Köster, Jacques Massé, Miguel Ñiquen, Hiroshi Nishida, Yoshioki Oozeki, Isabel Palomera, Suzana A. Saccardo, Alberto Santojanni, Rodolfo Serra, Stylianos Somarakis, Yorgos Stratoudakis, Andres Uriarte, Carl D. van der Lingen, Akihiko Yatsu
- Edited by Dave Checkley, Scripps Institution of Oceanography, University of California, San Diego, Jürgen Alheit, Yoshioki Oozeki, Claude Roy
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- Book:
- Climate Change and Small Pelagic Fish
- Published online:
- 08 January 2010
- Print publication:
- 20 August 2009, pp 191-255
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Summary
Summary
The assessment and management of small pelagic fish (SPF) stocks is particularly difficult and uncertain because their short life expectancy, characteristic aggregative behavior, rapid response to climate and environmental signals and large and variable natural mortality make them less tractable through traditional population dynamic models and assumptions. In this review we summarize the assessment and management approaches applied in 29 SPF stocks or management units (12 anchovy, 10 sardine, 4 herring, and 3 sprat). The review demonstrates that the assessment and management of SPF varies substantially in its approach and performance between stocks and regions. Most stocks have a scientific assessment program in place and a management approach that generally takes into account assessment results, but in some stocks management practices deviate substantially from scientific advice and in some, assessment and management processes are largely disconnected. It is concluded that only properly tailored scientific assessment and management programs can provide the speed of response and the flexibility of management that highly variable SPF demand. The most effective monitoring programs are based on fishery-independent surveys (daily egg production or/and hydroacoustics), while analyses based on catch per unit effort offer limited value. Most assessments, defined as what management uses to base its decisions on, rely on catch-at-age or yield per recruit models. Harvest strategies range from those driven by harvest control rules to those derived from outputs of best assessment runs. Some stocks use operating models based on age–structure model outputs or forward VPA. On the issue of scientific uncertainty some practitioners propose reducing it through additional science and measures, while others promote the development of management procedures robust to uncertainty.
THE TEOTIHUACAN BALLGAME AND THE BEGINNING OF TIME
- María Teresa Uriarte
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- Journal:
- Ancient Mesoamerica / Volume 17 / Issue 1 / January 2006
- Published online by Cambridge University Press:
- 28 June 2006, pp. 17-38
- Print publication:
- January 2006
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This paper proposes a reinterpretation of the Tepantitla murals long known as the Tlalocan. Taking into account the numerous representations of different kinds of ballgames on these walls, along with the instances of the Maya glyph for pu, pu or pu[h], or “Place of the Reeds” (i.e. Tollan), this paper argues that this mural represents Teotihuacan as prototypical civilized city associated with the beginning of time and the calendar. Further evidence is provided by the images of “Scattering Priests” in the adjacent room, all of whom wear crocodilian headdresses associated with Cipactli, the first day of the central Mexican calendar. In both rooms, images of Tlaloc with hallucinogenic water-lily buds in his mouth reflect associations with the sun, the calendar, and the underworld. The murals of Tepantitla can be interpreted as a coherent program representing the central role of the ballgame in establishing Teotihuacan as Tollan, the place where time began.
4 - Neighbourhood effects on sapling growth and survival in a neotropical forest and the ecological-equivalence hypothesis
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- By María Uriarte, Institute of Ecosystem Studies, Millbrook, Stephen P. Hubbell, University of Georgia and Smithsonian Tropical Research Institute, Robert John, University of Georgia and Smithsonian Tropical Research Institute, Richard Condit, Smithsonian Tropical Research Institute, Charles D. Canham, Institute of Ecosystem Studies, Millbrook
- Edited by David Burslem, University of Aberdeen, Michelle Pinard, University of Aberdeen, Sue Hartley, University of Sussex
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- Book:
- Biotic Interactions in the Tropics
- Published online:
- 25 August 2009
- Print publication:
- 08 September 2005, pp 89-106
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Summary
Introduction
In 1980 S. P. Hubbell and R. B. Foster began a long-term, large-scale study of tropical forest dynamics on Barro Colorado Island (BCI), Panama. The objective of the study was to test competing hypotheses about the maintenance of high tree species richness in the BCI forest, and in tropical moist forests more generally. Hubbell and Foster established a 50-ha permanent plot on the summit plateau of BCI, within which all free-standing woody plants with a stem diameter at breast height (DBH) of a centimetre or larger were tagged, measured, mapped and identified by 1982. Subsequent complete censuses of the BCI plot have been conducted from 1985 to 2000 at 5-year intervals. In setting up the BCI plot, Hubbell and Foster (1983) reasoned that whatever diversity-maintaining mechanisms were important, they would have to operate in a spatially dependent manner in communities of sessile plants such as the BCI tree community, which meant that the trees had to be mapped. A decade earlier, Janzen (1970) and Connell (1971) had independently proposed a spatially explicit ‘enemies hypothesis’, now known as the Janzen–Connell hypothesis. They hypothesized that host-specific seed and seedling predators were responsible for maintaining tropical tree diversity by causing dependence on density and frequency (rare species advantage), through an interaction between seed dispersal and density-dependent seed predation.
In 1980, there were essentially just two principal tropical forest diversity theories to test: the enemies hypothesis and its variants, and the ‘intermediate disturbance’ hypothesis (Connell 1977) and its variants that invoked a role for disturbances associated with opening, growth and closure of light gaps (e.g. Ricklefs 1978; Hartshorn 1978; Orians 1982; Denslow 1987).