Benefits of Spatial Regulation in a Multispecies System

Spatial heterogeneity in multispecies systems affects both ecological interactions and the composition of harvest. A bioeconomic model is used to analyze the nonselective harvest of two stocks with generalized ecological interaction and different persistent distributions across two spatial strata. Harvester response to aggregate effort controls is shown to partially dissipate rents relative to the case where the spatial distribution of effort can be specified. Numerical solutions for time paths of spatial (first-best) and aggregate (secondbest) input constraints indicate factors affecting their relative efficiency. In the scenarios studied, benefits of spatial specificity range from 0 to 15% of total net present value (NPV), depending upon the spatial correlation of stocks, their relative growth rates and prices, and the cost gradient across space. The benefits of spatial regulation are also heightened by the presence of ecological interaction, especially predator-prey dynamics.Bycatch, multispecies system, second-best regulation, spatial, Q20, Q22, Q28, Resource /Energy Economics and Policy,

A Stochastic Bioeconomic Model with Research

This paper provides an incremental extension of a stochastic renewable resource model (Pindyck 1984) to include population dynamics research; i.e., the rate of accrual of information regarding the stochastic evolution of the stock, as a dynamic choice variable. While Pindyck models variance in stock growth as an exogenous parameter, our formulation endogenizes this variance and characterizes the impact of scientific information accrual on both the harvest decision and the present value of rents resulting from harvest activity. We illustrate the theoretical existence of an internal optimum in research effort using a numerical example.stochastic bioeconomic model, stochastic control, fisheries management, population dynamics research, renewable resource, uncertainty, Resource /Energy Economics and Policy, Q2, Q22, C61,

Balancing Efficiency and Risk with Flexible Catch Balancing Policies

In multispecies fisheries managed with individual fishery quotas (IFQs), fishers targeting certain species often have insufficient quota to cover other jointly caught species. New Zealand employs a unique dual price-quantity system to address this problem. In lieu of acquiring quota, fishers can opt to pay a fee per unit of catch known as deemed value. Although designed primarily to create flexibility in catch balancing for individuals, this system can allow aggregate catches to exceed total allowable catches (TACs). The deemed value system reduces the likelihood that target species catches are constrained by TACs of bycatch species, but also increases the risk of overexploitation of bycatch species. Using a bioeconomic model, we evaluate the risk and efficiency of alternative deemed value policies in fisheries with one target and one bycatch species. Our simulations suggest that increasing deemed values above ex-vessel price in response to TACs being exceeded can control risk of overexploitation without reducing overall efficiency but does shift rents from owners of target species quota to owners of bycatch species quota

Dealing with Uncertainty in Management of Fisheries: Contradictory Advice and a New Approach

Fisheries management is complicated in nearly all fisheries by various types of uncertainty. Numerous economics and fisheries science publications prescribe adjustments to harvest strategies in the face of uncertainty. The conclusions and recommendations from this body of work are conflicting in many cases, are often dependent on critical but unrealistic assumptions, and are often impractical. In this paper, we review and compare the conclusions of economists and fisheries scientists on managing fisheries under uncertainty. We identify the common findings and discuss the divergent ones. We also attempt to explain why the theoretical conclusions of this literature have rarely been heeded by fisheries managers. Finally, we discuss a simulation based approach known as management strategy evaluation (MSE) that is designed to identify harvest strategies that are both robust to various types of uncertainty and capable of balancing multiple economic, social and biological objectives

On the bioeconomics of marine reserves when dispersal evolves

Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Natural Resource Modeling 28 (2015): 456-474, doi:10.1111/nrm.12075.Marine reserves are an increasingly used and potentially contentious tool in fisheries management. Depending upon the way that individuals move, no-take marine reserves can be necessary for maximizing equilibrium rent in some simple mathematical models. The implementation of no-take marine reserves often generates a redistribution of fishing effort in space. This redistribution of effort, in turn, produces sharp spatial gradients in mortality rates for the targeted stock. Using a two-patch model, we show that the existence of such gradients is a sufficient condition for the evolution of an evolutionarily stable conditional dispersal strategy. Thus, the dispersal strategy of the fish depends upon the harvesting strategy of the manager and vice versa. We find that an evolutionarily stable optimal harvesting strategy (ESOHS)—one which maximizes equilibrium rent given that fish disperse in an evolutionarily stable manner– - never includes a no-take marine reserve. This strategy is economically unstable in the short run because a manager can generate more rent by disregarding the possibility of dispersal evolution. Simulations of a stochastic evolutionary process suggest that such a short-run, myopic strategy performs poorly compared to the ESOHS over the long run, however, as it generates rent that is lower on average and higher in variability.This material is based upon work supported by funding from: The Woods Hole Oceanographic Institution's Investment in Science Fund to MGN; The Recruitment Program of Global Experts to YL; The University of Tennessee Center for Business and Economics Research to SL; and the U.S. National Science Foundation (NSF) through grants OCE-1031256, DEB-1257545, and DEB-1145017 to MGN, CNH-0707961 to GEH, DMS-1411476 to YL; and NSF Graduate Research Fellowships under Grant No. 1122374 to EAM and ES

Synergistic effects of UVR and simulated stratification on commensalistic phytoplankton–bacteria relationship in two optically contrasting oligotrophic Mediterranean lakes

An indirect effect of global warming is a reduction in the depth of the upper mixed layer (UML) causing organisms to be exposed to higher levels of ultraviolet (UVR, 280–400 nm) and photosynthetically active radiation (PAR, 400–700 nm). This can affect primary and bacterial production as well as the commensalistic phytoplankton–bacteria relationship. The combined effects of UVR and reduction in the depth of the UML were assessed on variables related to the metabolism of phytoplankton and bacteria, during in situ experiments performed with natural pico- and nanoplankton communities from two oligotrophic lakes with contrasting UVR transparency (high-UVR versus low-UVR waters) of southern Spain. The negative UVR effects on epilimnetic primary production (PP) and on heterotrophic bacterial production (HBP), intensified under increased stratification, were higher in the low-UVR than in the high-UVR lake, and stronger on the phytoplanktonic than on the heterotrophic bacterial communities. Under UVR and increased stratification, the commensalistic phytoplankton–bacteria relationship was strengthened in the high-UVR lake where excretion of organic carbon (EOC) rates exceeded the bacterial carbon demand (BCD; i.e., BCD : EOC(%) ratio 100). The greater UVR damage to phytoplankton and bacteria and the weakening of their commensalistic interaction found in the low-UVR lake indicates that these ecosystems would be especially vulnerable to UVR and increased stratification as stressors related to global climate change. Thus, our findings may have important implications for the carbon cycle in oligotrophic lakes of the Mediterranean region.This study was supported by the Ministerio Español de Medio Ambiente, Rural y Marino (PN2009/067), Ciencia e Innovación (CGL2011-23681), Junta de Andalucía (Excelencia CVI-02598 and P09-RNM-5376), Consejo Nacional de Investigaciones Científicas y Técnicas – CONICET (PIP no. 112-201001-00228), and Fundación Playa Unión. G. Herrera and C. Durán were supported by a Formación de Profesorado Universitario grant from the Spanish government. The authors are indebted to the staff of Sierra Nevada National Park and Lagunas de Ruidera Natural Park for permission to work, to E. Jiménez-Coll for the bacterial production analysis, and to D. Nesbitt for writing assistance in English

Sustitución de la torta de algodón por gallinaza y efecto del estado sexual en ceba de machos Holstein.

Algodó

The ENSO signature in sea-surface temperature in the Gulf of California

We analyzed 21 years of sea-surface temperature satellite images to explore the spatial signature of the El Niño-Southern Oscillation signal in the Gulf of California. We used empirical orthogonal function analysis to extract the principal mode of the nonseasonal sea-surface temperature variability and compared it to the spatial signature of the Southern Oscillation Index. The first mode accounted for 80% of nonseasonal variability and its amplitude time series was significantly correlated to the Southern Oscillation Index (r = −0.58,P \u3c 0.01). The amplitude of this mode and its statistical relation to the El Niño is stronger during winter, which suggests that forcing of sea-surface temperature variability occurs through the disruption of the wind-driven upwelling corridor along the eastern coast due to El Niño-related atmospheric teleconnections. We also examined weekly time series of coastal sea-surface temperature coastal anomalies along the coast of North America, including the interior of the Gulf of California, during the strong 1997–98 El Niño. We found a poleward propagating signal that reached the mouth of the Gulf of California at the end of spring and continued its poleward propagation along the west coast of the peninsula slightly delayed; it also resulted in warming inside the Gulf of California. This observation may provide an explanation for the variable extension of the El Niño signature along the Pacific coast of North America

Interactive effects of vertical mixing, nutrients and ultraviolet radiation: in situ photosynthetic responses of phytoplankton from high mountain lakes in Southern Europe

Global change, together with human activities, has resulted in increasing amounts of organic material (including nutrients) that water bodies receive. This input further attenuates the penetration of solar radiation, leading to the view that opaque lakes are more "protected" from solar ultraviolet radiation (UVR) than clear ones. Vertical mixing, however, complicates this view as cells are exposed to fluctuating radiation regimes, for which the effects have, in general, been neglected. Furthermore, the combined impacts of mixing, together with those of UVR and nutrient inputs are virtually unknown. In this study, we carried out complex in situ experiments in three high mountain lakes of Spain (Lake Enol in the National Park Picos de Europa, Asturias, and lakes Las Yeguas and La Caldera in the National Park Sierra Nevada, Granada), used as model ecosystems to evaluate the joint impact of these climate change variables. The main goal of this study was to address the question of how short-term pulses of nutrient inputs, together with vertical mixing and increased UVR fluxes modify the photosynthetic responses of phytoplankton. The experimentation consisted in all possible combinations of the following treatments: (a) solar radiation: UVR + PAR (280–700 nm) versus PAR (photosynthetically active radiation) alone (400–700 nm); (b) nutrient addition (phosphorus (P) and nitrogen (N)): ambient versus addition (P to reach to a final concentration of 30 μg P L−1, and N to reach N:P molar ratio of 31); and (c) mixing: mixed (one rotation from surface to 3 m depth (speed of 1 m 4 min−1, total of 10 cycles)) versus static. Our findings suggest that under ambient nutrient conditions there is a synergistic effect between vertical mixing and UVR, increasing phytoplankton photosynthetic inhibition and excretion of organic carbon (EOC) from opaque lakes as compared to algae that received constant mean irradiance within the epilimnion. The opposite occurs in clear lakes where antagonistic effects were determined, with mixing partially counteracting the negative effects of UVR. Nutrient input, mimicking atmospheric pulses from Saharan dust, reversed this effect and clear lakes became more inhibited during mixing, while opaque lakes benefited from the fluctuating irradiance regime. These climate change related scenarios of nutrient input and increased mixing, would not only affect photosynthesis and production in lakes, but might also further influence the microbial loop and trophic interactions via enhanced EOC under fluctuating UVR exposure.This work was supported by Ministerio Español de Medio Ambiente, Rural y Marino (PN2009/067) and Ciencia e Innovación (GLC2008-01127/BOS and CGL2011-23681), Junta de Andalucía (Excelencia CVI-02598), Agencia Nacional de Promoción Científica y Tecnológica (PICT 2007-1651) and Fundación Playa Unión; GH and CD were supported by the Spanish Government – Formación de Profesorado Universitario Grant

Bladder Mucosal CO2 Compared with Gastric Mucosal CO2 as a Marker for Low Perfusion States in Septic Shock

Recent reports indicate the possible role of bladder CO2 as a marker of low perfusion states. To test this hypothesis, shock was induced in six beagle dogs with 1 mg/kg of E. coli lipopolysaccharide, gastric CO2 (CO2-G) was measured with a continuous monitor, and a pulmonary catheter was inserted in the bladder to measure CO2 (CO2-B). Levels of CO2-B were found to be lower than those of CO2-G, with a mean difference of 36.8 mmHg (P < 0.001), and correlation between both measurements was poor (r2 = 0.16). Even when the correlation between CO2-G and ΔCO2-G was narrow (r2 = 0.86), this was not the case for the relationship between CO2-B and ΔCO2-B (r2 = 0.29). Finally, the correlation between CO2-G and base deficit was good (r2 = 0.45), which was not the case with the CO2-B correlation (r2 = 0.03). In our experience, bladder CO2 does not correlate to hemodynamic parameters and does not substitute gastric CO2 for detection of low perfusion states