scholarly journals Simulated Impacts of Juvenile Mortality on Gulf of Mexico Sturgeon Populations

2002 ◽  
Vol 2 ◽  
pp. 270-274 ◽  
Author(s):  
William B. Tate ◽  
Mike S. Allen
Keyword(s):  
Gulf Of Mexico ◽  
Population Viability ◽  
Juvenile Survival ◽  
Juvenile Mortality ◽  
Gulf Sturgeon ◽  
Four Levels ◽  
Age Structured ◽  
The Impact ◽  
Management And Conservation ◽  
Mortality Estimates

We used an age-structured computer model to assess the impact of changes in juvenile mortality on the Gulf of Mexico sturgeon population in the Suwannee River, Florida. We simulated population trends under four levels of annual juvenile mortality (20, 25, 30, and 35%). As the rate of mortality increased, population size decreased, and rates of population growth shifted from positive to negative. Our models indicated that juvenile survival is important to the success of gulf sturgeon populations, and mortality estimates are needed to predict population viability. We suggest that life history studies in estuaries should be conducted, and bycatch rates for commercial fisheries should be quantified to aid in the management and conservation of gulf sturgeon.

scholarly journals Model-based evaluation of school- and non-school-related measures to control the COVID-19 pandemic

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ganna Rozhnova ◽  
Christiaan H. van Dorp ◽  
Patricia Bruijning-Verhagen ◽  
Martin C. J. Bootsma ◽  
Janneke H. H. M. van de Wijgert ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Additional Benefit ◽  
Transmission Model ◽  
Time Points ◽  
School Based ◽  
Admission Data ◽  
Age Structured ◽  
The Impact ◽  
Pandemic Wave

AbstractThe role of school-based contacts in the epidemiology of SARS-CoV-2 is incompletely understood. We use an age-structured transmission model fitted to age-specific seroprevalence and hospital admission data to assess the effects of school-based measures at different time points during the COVID-19 pandemic in the Netherlands. Our analyses suggest that the impact of measures reducing school-based contacts depends on the remaining opportunities to reduce non-school-based contacts. If opportunities to reduce the effective reproduction number (Re) with non-school-based measures are exhausted or undesired and Re is still close to 1, the additional benefit of school-based measures may be considerable, particularly among older school children. As two examples, we demonstrate that keeping schools closed after the summer holidays in 2020, in the absence of other measures, would not have prevented the second pandemic wave in autumn 2020 but closing schools in November 2020 could have reduced Re below 1, with unchanged non-school-based contacts.

scholarly journals Understanding drivers of wild oyster population persistence

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mickael Teixeira Alves ◽  
Nick G. H. Taylor ◽  
Hannah J. Tidbury
Keyword(s):  
Population Density ◽  
Carrying Capacity ◽  
Pacific Oyster ◽  
Wild Population ◽  
Population Persistence ◽  
Oyster Reefs ◽  
Oyster Population ◽  
Northern European ◽  
Age Structured ◽  
The Impact

AbstractPersistence of wild Pacific oyster, Magallana gigas, also known as Crassostrea gigas, has been increasingly reported across Northern European waters in recent years. While reproduction is inhibited by cold waters, recent warm summer temperature has increased the frequency of spawning events. Although correlation between the increasing abundance of Pacific oyster reefs in Northern European waters and climate change is documented, persistence of wild populations may also be influenced by external recruitment from farmed populations and other wild oyster populations, as well as on competition for resources with aquaculture sites. Our understanding of the combined impact of the spawning frequency, external recruitment, and competition on wild population persistence is limited. This study applied an age-structured model, based on ordinary differential equations, to describe an oyster population under discrete temperature-related dynamics. The impact of more frequent spawning events, external recruitment, and changes in carrying capacity on Pacific oyster density were simulated and compared under theoretical scenarios and two case studies in Southern England. Results indicate that long term persistence of wild oyster populations towards carrying capacity requires a high frequency of spawning events but that in the absence of spawning, external recruitment from farmed populations and other wild oyster populations may act to prevent extinction and increase population density. However, external recruitment sources may be in competition with the wild population so that external recruitment is associated with a reduction in wild population density. The implications of model results are discussed in the context of wild oyster population management.

Impact of Land Conservation Technologies on Agricultural Productivity in Tanzania

Utafiti ◽  
2015 ◽  
Vol 11 (1-2) ◽  
pp. 33-66
Author(s):  
Onesmo Selijio
Keyword(s):  
Land Management ◽  
Water Conservation ◽  
Crop Yields ◽  
Maize Crop ◽  
Cross Sectional ◽  
Inorganic Fertilizers ◽  
The Government ◽  
The Impact ◽  
Management And Conservation ◽  
Conservation Technologies

Land management and conservation have been considered the most important aspects of sustainable productivity in economically developing countries where land degradation is a major challenge. In Tanzania, both the government and international organizations have been promoting adoption of land management and conservation technologies (LMCTs) for a long time. This paper establishes the impact of three LMCTs – soil water conservation technologies and erosion control (SWCEC), organic and inorganic fertilizers – on maize crop yields in different rainfall zones, using national panel survey data. The study employs static panel models to analyse the two-period data sets for 2008-2009 and 2010-2011. The results indicate that adoption of LMCTs do contribute significantly to maize yield. The greatest effects of organic and SWCEC methods on crop yield were realized in low rainfall zones, while that of inorganic fertilizers was observed in high rainfall zones. These findings support previous cross-sectional data analyses, suggesting for policy makers that a blanket land management and conservation programme applied uniformly to all agro-ecological zones is not strategically beneficial. The advisability of a technology employed in a given zone should be supported by local knowledge and research findings culled from that particular area.

Impacts of the COVID-19 pandemic on protected area management and conservation outcomes in Mexico

2021 ◽  
Author(s):  
Kathryn Powlen ◽  
Kelly W. Jones ◽  
Elva Ivonne Bustamante Moreno ◽  
Maira Abigail Ortíz Cordero ◽  
Jennifer N. Solomon ◽  
...  
Keyword(s):  
Management Support ◽  
Short Term ◽  
Group Data ◽  
Management Capacity ◽  
Focus Group Data ◽  
Technical Capacity ◽  
The Impact ◽  
Relief Efforts ◽  
Management And Conservation

Protected areas (PAs) are under immense pressure to safeguard much of the world’s remaining biodiversity and can be strained by unpredicted events such as the COVID-19 pandemic. Understanding the extent of the pandemic on PA inputs, mechanisms, and conservation outcomes is critical for recovery and future planning to buffer against these types of events. We use survey and focus group data to quantify the impact of the pandemic on Mexico’s PA network and outline the pathways that led to conservation outcomes. On average, across 62 PAs, we find substantial changes in management capacity, monitoring, and tourism, and a slight increase in non-compliant activities. Our findings highlight the need to increase short-term relief efforts and long-term livelihood diversification initiatives for communities dependent on tourism, who were most vulnerable during the pandemic. Increased management support, including technical capacity and financial resources, could also better sustain management activities in future shocks.

scholarly journals Estimating post-release mortality of European sea bass based on experimental angling

2018 ◽  
Vol 75 (4) ◽  
pp. 1483-1495 ◽  
Author(s):  
Wolf-Christian Lewin ◽  
Harry Vincent Strehlow ◽  
Keno Ferter ◽  
Kieran Hyder ◽  
Jan Niemax ◽  
...  
Keyword(s):  
Stock Assessment ◽  
Sea Bass ◽  
Specific Information ◽  
Experimental Conditions ◽  
European Sea Bass ◽  
Air Exposure ◽  
Cumulative Impact ◽  
The Impact ◽  
Mortality Estimates ◽  
Country Specific

Abstract European sea bass (Dicentrarchus labrax) is an important target species for recreational and commercial fisheries. In recent years, the spawning stock biomass has declined markedly in some areas, and strict management measures have been introduced. However, the development of appropriate stock assessment and fisheries management has been hampered by a lack of information on post-release mortality. This study investigated post-release mortality of sea bass captured with common recreational fishing gear under experimental conditions in an aquaculture facility over 10 d. Three experiments investigated: (i) the effects of different bait types; (ii) the impact of prolonged air exposure; and (iii) the impact of deep hooking on post-release mortality. By combining the experimental results with country-specific information on sea bass angling practices, estimates of post-release mortality are provided for the northern sea bass stock. No mortality was observed for sea bass captured on artificial baits. The use of natural baits resulted in a mortality of 13.9% (95% CI = 4.7–29.5%), which was associated with deep hooking, hooking injuries, and prolonged air exposure. The use of artificial baits and short air exposure (≤30 s) increased survival probability, whereas deep hooking resulted in 76.5% (95% CI = 50.0–93.2%) mortality. Depending on country-specific angling practices, post-release mortality estimates ranged from 2.8% to 9.1% (mean = 5.0%, 95% CI = 1.7–14.4%) for northern sea bass. Despite these relatively low mortality estimates, post-release mortality should be considered in stock assessments as its cumulative impact may be high. Moreover, post-release mortality can be reduced by implementing species-specific best practice guidelines.

scholarly journals Assessing the impact of oil-related activities on benthic macroinfauna assemblages of the Campeche shelf, southern Gulf of Mexico

2005 ◽  
Vol 289 ◽  
pp. 89-107 ◽  
Author(s):  
HA Hernández Arana ◽  
RM Warwick ◽  
MJ Attrill ◽  
AA Rowden ◽  
G Gold-Bouchot
Keyword(s):  
Gulf Of Mexico ◽  
Southern Gulf Of Mexico ◽  
The Impact
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