Offtake Data Research Articles

Combining offtake and participatory data to assess the sustainability of a hunting system in northern Congo

AbstractResearch suggests that bushmeat is hunted at unsustainable rates throughout much of the Congo basin, although accurately measuring hunting sustainability is challenging. Offtake data can contribute towards sustainability assessments, and when incorporated with information on hunters' strategies, can be used to monitor changes in hunting dynamics. We used a combination of (1) a long‐term, quantitative yet low‐resolution hunting offtake data set, (2) qualitative data acquired through participatory methods, and (3) a high‐resolution offtake survey, to examine the changes in a hunting system undergoing change due to new roads and associated socio‐economic developments in northern Republic of the Congo. Our results indicated that while the conclusions drawn from the different data sets were broadly the same (indicating wildlife depletion, particularly in one hunting zone), the results of the analysis of the participatory and the high‐resolution offtake data set provided an explanation for trends in the long‐term low‐resolution offtake data set, including the degree to which long‐term trends are due to changes in hunting strategy, or in underlying wildlife populations. We discuss how participatory hunter surveys can be used to distinguish between changes in prey populations and changes in hunting strategy in long‐term low‐resolution hunting offtake data sets, therefore, improving the effectiveness of long‐term offtake data sets to assess sustainability of hunting.

Interpreting long-term trends in bushmeat harvest in southeast Cameroon

Measuring hunting sustainability across West/Central African forests remains a challenge. Long-term assessment of trends is crucial. Via hunter-reported surveys we collected offtake data in three villages near the Dja Biosphere Reserve (southeast Cameroon). During four months (March–June) in 2003, 2009 and 2016, we gathered information on hunters, prey species and number of carcasses brought to the three settlements. Because it was not possible to record hunter effort i.e. the time a hunter spent pursuing animals or setting traps, to calculate catch per unit effort (CPUE), we used catch per hunter per day (CPHD) to document hunter returns. We then used the changes in the mean body mass indicator (MBMI) throughout the study period to test for defaunation in the three villages. Differences in CPHD and MBMI by month and year, between villages and hunting method, were investigated using Tweedie regression models. For all species pooled, we found that the mean CPHD remained relatively constant between 2003 and 2016. There was an observed shift from traps to firearms during the study period. CPHD for each of the seven most hunted species did not vary significantly during the entire study period, and a similar change from traps to firearms was observed. MBMI also remained stable for all species pooled, but significantly declined in the remotest village. Starting MBMI values for this village were higher than for the other two settlements perhaps because wildlife here is less depleted. Although hunter effort data may be difficult to obtain over long time periods, CPHD and MBMI may be useful tools as a measure of impact of hunters on prey populations.

Participatory Monitoring and Management of Subsistence Hunting in the Piagaçu-Purus Reserve, Brazil

The Sustainable Development Reserve (RDS) model in Brazil provides legal context for monitoring wildlife with the involvement of local populations in gathering data and developing strategies for sustainable use. We present results of one year of self monitoring by hunters in five communities within the RDS-PP, discuss how the observed patterns reflect local hunting regulations, and suggest how this information could be incorporated into a formal management system. In addition to the offtake data, we interviewed hunters, inquiring about informal community hunting norms and agreements, and analysed the content of 19 rules in the reserve's management plan. 509 hunting events were recorded by 37 of the 104 families present (35%). Self monitoring permitted the evaluation of temporal and spatial fluctuations of hunting activities, notably regarding ease of canoe transport during the high-water season. Though communities have been apprehensive about developing regulations for subsistence hunting, one of the communities had developed a set of formal rules. Hunting for commercial sale to outsiders and restrictions on external hunters are concerns shared by the local population and the reserve management agencies. Such data and understanding are crucial to the management of protected areas in the Brazilian Amazon, where governance is often limited.

Social and Ecological Change over a Decade in a Village Hunting System, Central Gabon

Despite widespread recognition of the major threat to tropical forest biological diversity and local food security posed by unsustainable bushmeat hunting, virtually no long-term studies tracking the socioecological dynamics of hunting systems have been conducted. We interviewed local hunters and collected detailed hunting data to investigate changes in offtake and hunter characteristics over 10 years (2001-2010) in Dibouka and Kouagna villages, central Gabon, in the context of hunter recollections of longer term trends since the 1950s. To control for changes in hunter behavior, such as trap location and characteristics, we report hunting offtake data per trap. Our results suggest the hunting area was already highly depleted by 2001; local hunters reported that 16 large-bodied prey species had become rare or locally extirpated over the last 60 years. Overall, we observed no significant declines in hunting offtake or changes in species composition from 2001 to 2010, and offtakes per trap increased slightly between 2004 and 2010. However, trapping distance from the villages increased, and there was a switch in hunting techniques; a larger proportion of the catch was hunted with guns in 2010. The number of hunters declined by 20% from 2004 to 2010, and male livelihood activities shifted away from hunting. Hunters with the lowest hunting incomes in 2004 were more likely than successful hunters to have moved away from the village by 2010 (often in response to alternative employment opportunities). Therefore, changes in trap success (potentially related to biological factors) were interacting with system-level changes in hunter number and composition (related to external socioeconomic factors) to produce a relatively static overall offtake. Our results highlight the importance of understanding the small-scale context of hunting to correctly interpret changes or apparent stasis in hunting effort and offtake over time.

Anticipating Vulnerability to Climate Change in Dryland Pastoral Systems: Using Dynamic Systems Models for the Kalahari

It is vitally important to identify agroecosystems that may cease functioning because of changing climate or land degradation. However, identifying such systems is confounded on both conceptual and methodological grounds, especially in systems that are moving toward thresholds, a common trait of dryland environments. This study explores these challenges by analyzing how a range of external pressures affect the vulnerability of dryland pastoral systems in the Kalahari. This is achieved by employing dynamic systems modeling approaches to understand the pathways by which communities became vulnerable to drought. Specifically, we evaluate how external pressures have changed: (1) different agroecosystems' abilities to tolerate drought, i.e., ecosystem resilience; (2) rural communities’ abilities to adapt to drought, mediated via their access to assets; and (3) the ability of institutions and policy interventions to play a role in mediating drought-related crises, i.e., socio-political governance. This is done by reanalyzing ecological and participatory research findings along with farm-scale livestock offtake data from across the Kalahari in Botswana. An iterative process was followed to establish narratives exploring how external drivers led to changes in agroecosystem resilience, access to assets, and the institutional capacity to buffer the system. We use “causal loop diagrams” and statistical dynamic system models to express key quantitative relationships and establish future scenarios to help define where uncertainties lie by showing where the system is most sensitive to change. We highlight how that greater sharing of land management knowledge and practices between private and communal land managers can provide ‘win-win-win’ benefits of reducing system vulnerability, increasing economic income, and building social capital. We use future scenario analyses to identify key areas for future studies of climate change adaptation across the Kalahari.

Experimental investigation on onset criteria of liquid/gas entrainment in the header-feeder system of CANDU

An experimental study has been performed to investigate the off-take phenomena at the header-feeder systems (horizontal header pipe with multiple feeder branch pipes) in a CANDU (CANadian Deuterium Uranium) reactor with the branch orientation varies ±36° or ±72°. In order to evaluate the applicability of the conventional correlations used in the safety analysis code, RELAP5-Mod3, the test facility is designed with the 1/2 scale of the CANDU 6. It was found that the data set for the top, bottom and side branches are in a good agreement with the correlations used. However, for the specific angled branches, ±36° and ±72°, the onsets of off-take data and quality data showed large deviation with the conventional model inside RELAP5-MOD3. Furthermore, based on the uncertainty analysis, the conventional 2.5 power law needs to be modified. The present experimental data set can be useful for the construction of the general correlation considering the arbitrary branch orientation.

Evidence for post‐depletion sustainability in a mature bushmeat market

Summary The trade in wild animals for meat, or ‘bushmeat’, is perceived as one of the most important threats to wildlife in the tropics. Unsustainable bushmeat extraction also threatens the loss of livelihoods. However, the long‐term persistence of the bushmeat trade, documented in Africa over several centuries, suggests that the trade can be sustainable. In this study, we investigate sustainability in a mature bushmeat market in West Africa (Takoradi, Ghana). Our study, conducted over January and February 2000, combined biological and socio‐economic approaches. Offtake data, including information on species identity, capture location and sales price, were collected in a market survey. Species biological data, and the historical price of bushmeat and its substitutes (fish and domestic meat), were taken from the literature. The theoretical sustainable yield for each species was estimated using standard algorithms. We tested the hypothesis that the current trade is unsustainable with four predictions: that (1) the number of animals extracted exceeds a theoretical sustainable yield, (2) larger taxa are depleted more heavily close to the city, (3) the price of bushmeat has outstripped inflation and (4) the price of alternatives, such as domestic meat and fish, has fallen relative to the price of bushmeat. None of these predictions were supported. There was therefore no evidence of unsustainability. Analysis of market profiles and hunter reports suggest that the present pattern of sustainability is the result of a series of non‐random extinctions from historical hunting. Vulnerable taxa (slow reproducers) have been depleted heavily in the past, so that only robust taxa (fast reproducers), such as rodents and small antelope, are now traded. These robust taxa are supplied from a predominantly agricultural landscape around the city. Synthesis and applications. The bushmeat trade can have a severe impact on species that are vulnerable to overexploitation. However, once these species have disappeared, the remaining species may be harvested sustainably. Bushmeat management policy might therefore be improved by adopting a two‐pronged approach in which vulnerable species are protected from hunting, but robust species are allowed to supply a sustainable trade. The productivity of agricultural landscapes for many bushmeat species indicates that these areas may play an important role in supporting a sustainable bushmeat trade.

Liquid entrainment and off-take through the break at the top of a vessel

In order to determine the bleed capacity of the safety depressurization system (SDS) of Advanced Power Reactor 1400 (APR1400) in the case of total loss of feed water (TLOFW), we performed an experimental study of liquid entrainment and liquid off-take from the swelled two-phase mixture surface in a vessel. A total of 220 experimental data on the entrainment and off-take are obtained using a test vessel with a height of 2.0 m and an inner diameter of 0.3 m and a top break with a diameter of 0.05 m. Two-phase mixture levels are measured by an ultrasonic sensor within ±1.77% with respect to the visual level data. Droplet entrainment data are obtained with and without the top break and are compared with the existing pool entrainment data. The present droplet entrainment data have higher values than the existing pool entrainment data due to (a) the pulling toward the break of the liquid deentrained on the top wall of the vessel and (b) gas acceleration in the vicinity of the break. In the present experiment, droplet entrainment, E fg, strongly depends upon j g * / h * and is proportional to the seventh power of j g * / h * in the same way as the off-take data. The empirical correlation for the onset of off-take is developed in terms of the Froude number ( Fr g) at the break and the non-dimensional inception height ( h b/ d). This correlation shows agreement with the present experimental data within ±15%. The present off-take quality data show agreement with Schrock's off-take quality correlation with the rms error of 15.8%.

Effectiveness of the water-insoluble component of triple superphosphate for yield and phosphorus uptake by plants

The water-insoluble phosphorus (P) component (‘residue source’) was separated from four commercial triple superphosphate (TSP) products and its agronomic effectiveness evaluated. Two of the TSP products were sourced from the USA and two from the UK. Effectiveness was measured using a pot trial technique with ryegrass as the test crop. The residue sources were evaluated on 13 soils varying in key properties: readily plant-available P, texture, pH and organic matter content. Four of the soils were from Germany, one from Spain, five from the UK and three from France. Grass dry-matter yield and P offtake were measured at every cut on every soil. For both of these variables, significant responses to applied P were obtained on all soils. Mono-calcium phosphate (MCP) was used as the comparative P source and effectiveness of the residue sources was estimated relative to that of MCP. Using dry-matter data, the residue sources were 44–87% as effective as MCP; P offtake data provided corresponding estimates of 35–79%. Both methods of estimation indicated the same ranking of residue sources in terms of relative effectiveness, those derived from USA products being more effective than those derived from UK products. The ranking was the same for all soils. The effectiveness of the residue sources relative to that of MCP appeared little affected by measured soil properties: texture, pH, available P or organic carbon content. The results indicate there is little difference in agronomic effectiveness of TSP products with water solubility greater than 85%.

Impact of veterinary treatments on goat mortality and offtake in the semi-arid area of Mali

Mortality and offtake data were collected in the semi-arid area of Mali from 1518 goats under traditional management, over a period of 1.5 years. A preliminary survey indicated that health care was a major management problem. Three treatment groups were formed: (1) control, (2) a group of animals vaccinated against Pasteurellosis, Anthrax and ‘Peste des petits ruminants’ (PPR), and (3) a group vaccinated against these diseases and an additional deworming. Goats were allocated randomly within the flocks to each treatment group. Vaccinations and deworming were done over a period of 1 year. Average kid mortality rate was 18%. About 40% of deaths in kids were the result of malnutrition, losses due to predators, and injuries. Veterinary treatments, including vaccinations and deworming, had no statistically significant impact on kid mortality. Kid mortality can best be reduced by improving management practices. In goats older than 6 months the package of veterinary treatments reduced mortality significantly. In particular, deworming reduced mortality. Mortality rate was 16% in controls, 12% in vaccinated goats and 4% in vaccinated and dewormed goats. Impact of vaccinations and vaccinations plus deworming on the production system was limited. Veterinary treatments had no effect on weight development of the goats. Also, no significant increase in offtake was found in treated animals. Thus, number of goats increased in the vaccinated and dewormed group. It is concluded that it is advisable to vaccinate goats to reduce the risk of periodic outbreaks of diseases. Feasibility of deworming will depend on the costs involved.

Thermoplastic Elastomers—Three Decades of Progress

Abstract In these three decades of progress, thermoplastic elastomers have risen in 1987 to a position of tenth in the order of commercial thermoplastic sales in the U.S.A., with a growth rate, 1986–1987, of 9.7%. It is very probable that the quantity shown for 1987 sales, 441 million pounds, is low, since it is well known that the largest producer of styrenic TPEs does not report offtake data. Much of the styrenic TPE goes to the adhesive industry, which also is very secretive in regard to materials consumption information. Thus, the 1986–1987 reported growth rate of 9.7% is on the low side. Another indicator of progress in the growth of TPEs has been illustrated by the number of product introductions from January 1986 to June 1987. During that period, TPEs led the major thermoplastics with the introduction of 270 new product types, and the nylons were a close second with 250. A third estimate of the explosive growth in TPEs may be seen in Table V which lists the number of manufacturers of TPEs in 1975, 1985, and 1987, increasing from 10 to 28 to 50. To summarize, the present thermoplastic elastomers, now high-volume commercial products, had roots in the chemistry and technology of polymers in the 1920's. Throughout the history of the “Roots” period one can detect precursor events from which several TPEs could have been foreseen. In each of the three decades of progress, major advances were made in the technology, physical properties, availability, and utilization of TPEs. The numbers of these increased in each succeeding period. Several paradigms appear in this review, for example: 1. The triblock styrene-diene A-B-A copolymers, morphology, and elastomeric character, in the first decade. 2. The copolyesters with (A−B)n morphology and greatly enhanced physical properties in the second decade. 3. The dynamically-vulcanized blends of EPDM and PP, followed in time by the concept of compatibilization to permit practical blends of NBR and PP in the third decade. Throughout these periods, growth was catalyzed by the favorable economics of manufacturing finished elastomeric products via low-cost thermoplastic processing techniques as compared with thermoset rubber processes. The reuse of scrap also provided a major incentive. In addition to these, the concept of component integration is now showing a path toward even more cost reduction incentives. New applicational areas continue to appear. One of these, blending relatively small amounts of TPEs with existing large volume thermoplastics, promises to provide extremely large offtakes of TPEs in the next decade. I am sure that the numbers of papers presented in symposia at meetings of the Rubber Division of the American Chemical Society confirm the continued explosive growth of TPEs we have seen in these past three decades.

Interaction between cow slurry and 15N‐labelled calcium nitrate as fertilisers for ryegrass production

AbstractA field‐plot experiment with ryegrass was carried out to study the interaction between 15N‐labelled calcium nitrate at 0, 25 and 50 kg N ha−1 and cow slurry supplying 0, 33 and 68 kg NH‐N ha−1. Treatments were applied on a single occasion to a site where first‐cut silage had just been removed. The effects of the treatments on dry matter yield, nitrogen offtake and % utilisation of calcium nitrate were measured in two cuts of herbage taken after 5 and 17 weeks. Increases in dry matter yield due to slurry were smaller at the 50 kg N ha−1 rate of calcium nitrate than at the 0 and 25 kg N ha−1 rates, possibly due to non‐linearity of the yield response curve. Nitrogen offtake data indicated that the two sources of nitrogen were taken up additively by the ryegrass. Rate of calcium nitrate application or slurry treatment had no significant effect on the % utilisation of calcium nitrate in either cut. The average values for % utilisation of calcium nitrate over all treatments were 50 and 7% at cuts 1 and 2, respectively. There was no evidence for enhanced rates of denitrification in the presence of slurry. Recovery values of nitrogen (estimated by difference) were lower for NH‐N in slurry than for calcium nitrate. Volatilisation of ammonia from surface‐spread slurry is the most likely reason for the low efficiency of NH‐N in slurry.