Marine fish stocks are an important part of the world food system and are particularly important for many of the poorest people of the world. Most existing analyses suggest overfishing is increasing, ...and there is widespread concern that fish stocks are decreasing throughout most of the world. We assembled trends in abundance and harvest rate of stocks that are scientifically assessed, constituting half of the reported global marine fish catch. For these stocks, on average, abundance is increasing and is at proposed target levels. Compared with regions that are intensively managed, regions with less-developed fisheries management have, on average, 3-fold greater harvest rates and half the abundance as assessed stocks. Available evidence suggests that the regions without assessments of abundance have little fisheries management, and stocks are in poor shape. Increased application of area-appropriate fisheries science recommendations and management tools are still needed for sustaining fisheries in places where they are lacking.
Thermo-optic actuators based on bulk materials are considered too slow in applications such as laser frequency control. The availability of high-quality optical materials that have extremely fast ...thermal response times, such as diamond, present an opportunity for increasing performance. Here, diamond thermal actuators are investigated for configurations that use a planar thermal resistive layer applied to a heat-sinked rectangular prism. A general analytical formulation is obtained which simplifies substantially for high thermal conductivity such as diamond. Expressions for modulation depth, bandwidth and power requirements are obtained as functions of modulator dimensions and heat-transfer coefficients. For a 1 mm × 1 mm cross-section diamond at wavelength of 1 μm, around 450 W of applied heat power is needed to achieve a π phase shift at a modulation frequency of 2 kHz.
Background: Macronutrient “preloads” can stimulate glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), slow gastric emptying, and reduce postprandial glycemic ...excursions. After sweet preloads, these effects may be signaled by sodium-glucose cotransporter-1 (SGLT1), sweet taste receptors, or both.Objective: We determined the effects of 4 sweet preloads on GIP and GLP-1 release, gastric emptying, and postprandial glycemia.Design: Ten healthy subjects were studied on 4 separate occasions each. A preload drink containing 40 g glucose, 40 g tagatose/isomalt mixture (TIM), 40 g 3-O-methylglucose (3OMG; a nonmetabolized substrate of SGLT1), or 60 mg sucralose was consumed 15 min before a 13C-octanoic acid–labeled mashed potato meal. Blood glucose, plasma total GLP-1 and GIP, serum insulin, and gastric emptying were determined.Results: Both glucose and 3OMG stimulated GLP-1 and GIP release in advance of the meal (each P < 0.05), whereas TIM and sucralose did not. The overall postprandial GLP-1 response was greater after glucose, 3OMG, and TIM than after sucralose (P < 0.05), albeit later after TIM than the other preloads. The blood glucose and insulin responses in the first 30 min after the meal were greatest after glucose (each P < 0.05). Gastric emptying was slower after both 3OMG and TIM than after sucralose (each P < 0.05).Conclusions: In healthy humans, SGLT1 substrates stimulate GLP-1 and GIP and slow gastric emptying, regardless of whether they are metabolized, whereas the artificial sweetener sucralose does not. Poorly absorbed sweet tastants (TIM), which probably expose a greater length of gut to nutrients, result in delayed GLP-1 secretion but not in delayed GIP release. These observations have the potential to optimize the use of preloads for glycemic control. This trial was registered at www.actr.org.au as ACTRN12611000775910.
This article examines the role of risk aversion on the sustainable management of mixed fisheries. We consider a bio-economic model of multiple species harvested by a single fleet with uncertain costs ...of effort. We assume that the regulatory agency aims at reaching MMEY (Multispecies Maximum Economic Yield) by maximizing the expected utility of total profits, where the utility function captures risk aversion. We show analytically that such a risk-averse MMEY mitigates the risk of biological and economic overexploitation of the different species and thus of biodiversity loss. However excessively high risk aversion also may also lessen food production at MMEY. Thus, risk aversion implies a trade-off between different bio-economic goals. These findings are illustrated with the case study of the Australian South East Fishery, where intermediate risk aversion levels allow for balanced bio-economic management objectives, therefore fostering sustainability.
Intestinal production of endocannabinoid and oleoylethanolamide (OEA) is impaired in high-fat diet/obese rodents, leading to reduced satiety. Such diets also alter the intestinal microbiome in ...association with enhanced intestinal permeability and inflammation; however, little is known of these effects in humans. This study aimed to 1) evaluate effects of lipid on plasma anandamide (AEA), 2-arachidonyl- sn-glycerol (2-AG), and OEA in humans; and 2) examine relationships to intestinal permeability, inflammation markers, and incretin hormone secretion. Twenty lean, 18 overweight, and 19 obese participants underwent intraduodenal Intralipid infusion (2 kcal/min) with collection of endoscopic duodenal biopsies and blood. Plasma AEA, 2-AG, and OEA (HPLC/tandem mass spectrometry), tumor necrosis factor-α (TNFα), glucagon-like peptide-1 (GLP-1), and glucose-dependent insulinotropic peptide (GIP) (multiplex), and duodenal expression of occludin, zona-occludin-1 (ZO-1), intestinal-alkaline-phosphatase (IAP), and Toll-like receptor 4 (TLR4) (by RT-PCR) were assessed. Fasting plasma AEA was increased in obese compared with lean and overweight patients ( P < 0.05), with no effect of BMI group or ID lipid infusion on plasma 2-AG or OEA. Duodenal expression of IAP and ZO-1 was reduced in obese compared with lean ( P < 0.05), and these levels related negatively to plasma AEA ( P < 0.05). The iAUC for AEA was positively related to iAUC GIP ( r = 0.384, P = 0.005). Obese individuals have increased plasma AEA and decreased duodenal expression of ZO-1 and IAP compared with lean and overweight subjects. The relationships between plasma AEA with duodenal ZO-1, IAP, and GIP suggest that altered endocannabinoid signaling may contribute to changes in intestinal permeability, inflammation, and incretin release in human obesity.
Consideration of economic outcomes is commonplace in most fisheries management systems globally, although only a few jurisdictions have adopted an economic objective as the primary target for ...fisheries management. Such an objective has been adopted for Australia's federally managed fisheries, with maximum economic yield (MEY) identified as the primary management objective. Correspondingly, target reference points defined in terms of biomass (i.e., B.sub.MEY) are used in harvest control rules. In the absence of explicit B.sub.MEY estimates, proxy estimates based on maximum sustainable yield (i.e., B.sub.MSY) are used. Identifying B.sub.MEY in multi-species fisheries is complicated as most stock assessments are undertaken at the individual species level, but economic activity occurs across species. This is further complicated when different fishing activities using different fishing gears and targeting practices (i.e., metiers) are present in a fishery. We employ an age-structured bioeconomic model to estimate B.sub.MEY for key species in a multi-species, multi-metier fishery. We find that optimal biomass levels are substantially higher than those assumed under the current proxy-based system, and that the economic targets are sensitive to prices and fishing costs, both of which change over time.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
As climate-driven environmental changes and anthropogenic perturbations increasingly affect ecological systems, the number of abrupt phase shifts in ecosystem dynamics is rising, with far-reaching ...ecological, economic and social effects. These shifts are notoriously difficult to study, anticipate and manage. Although indicators of impending phase shifts in ecosystems have been described theoretically, they have only been observed empirically either after the fact or under controlled experiments. Here we demonstrate the usefulness of case-specific simulation models to estimate tipping points in the dynamics of real ecological systems, characterise how these thresholds may vary depending on local conditions and derive safe management targets associated with low risk of undesirable phase shifts. Under the combined effects of ocean changes and fishing, inshore rocky reefs in eastern Tasmania can transition from dense seaweed beds to sea urchin ‘barrens’ habitat, realising severe local loss of habitat, productivity and valuable fisheries. Using Monte-Carlo simulations with a validated model that realistically captures reef dynamics, we characterise the hysteresis in community dynamics and the variability in ecological thresholds along the gradient of environmental conditions. Simulation suggests that prevention of ongoing sea urchin destructive grazing of macroalgal beds is achievable but the yet-to-be-observed restoration of seaweed beds from extensive sea urchin barrens is highly unlikely. To guide management against undesirable phase shifts, we define target points associated with low risk of widespread barrens formation and show that, along with sea urchin culling, recognising the role of lobsters in mitigating sea urchin destructive grazing through predation is key to maintain reef productivity.
Abstract
For the Blue Foods economy—those sectors that gain value from the biological productivity of the oceans such as fisheries and aquaculture—climate shocks pose an existential threat. Species ...range shifts, harmful algal blooms, marine heatwaves, low oxygen events, coral bleaching, and hurricanes all present a serious economic risk to these industries, and yet there exist few financial tools for managing these risks. This contrasts with agriculture, where financial tools such as insurance are widely available for managing numerous weather-related shocks. Designing financial tools to aid risk management, such as insurance, for equitable resilience against marine climate shocks will give coastal communities access to the necessary means for reducing their sensitivity to climate shocks and improving their long-term adaptive capacity. We suggest that a convergence of the insurance industry and marine sectors, fostered through collaboration with governments, academics, and NGOs will help usher in new forms of insurance, such as ocean-index or parametric insurance. These new risk-management tools have the potential to help incentivize sustainable use of living marine resources, as well as strengthening the economic resilience of coastal communities to climate change.
Abstract
Electronic monitoring (EM) systems have become functional and cost-effective tools for the conservation and sustainable harvesting of marine resources. EM is an alternative to on-board ...observers, which produces video segments that can subsequently be reviewed by analysts. It is currently used in a range of fisheries. There are two major challenges to the widespread adoption of EM. One is the large storage requirement for the video footage recorded and the other is the long time required by analysts to review the video footage. We propose an automated catch event detection framework to address these challenges. Our solution, based on deep learning techniques, automatically extracts video segments of catch events, which substantially reduces storage space and review time by analysts. Here, we demonstrate the framework using video footage from three longline fishing trips. The system recalled nearly 100% of the catch events across all trips.
Marine ecosystems evolve under many interconnected and area‐specific pressures. To fulfil society's intensifying and diversifying needs while ensuring ecologically sustainable development, more ...effective marine spatial planning and broader‐scope management of marine resources is necessary. Integrated ecological–economic fisheries models (IEEFMs) of marine systems are needed to evaluate impacts and sustainability of potential management actions and understand, and anticipate ecological, economic and social dynamics at a range of scales from local to national and regional. To make these models most effective, it is important to determine how model characteristics and methods of communicating results influence the model implementation, the nature of the advice that can be provided and the impact on decisions taken by managers. This article presents a global review and comparative evaluation of 35 IEEFMs applied to marine fisheries and marine ecosystem resources to identify the characteristics that determine their usefulness, effectiveness and implementation. The focus is on fully integrated models that allow for feedbacks between ecological and human processes although not all the models reviewed achieve that. Modellers must invest more time to make models user friendly and to participate in management fora where models and model results can be explained and discussed. Such involvement is beneficial to all parties, leading to improvement of mo‐dels and more effective implementation of advice, but demands substantial resources which must be built into the governance process. It takes time to develop effective processes for using IEEFMs requiring a long‐term commitment to integrating multidisciplinary modelling advice into management decision‐making.
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