Yield- and biomass-per-recruit analysis for rotational fisheries, with an application to the Atlantic sea scallop (Placopecten magellanicus)

A general model for yield-per-recruit analysis of rotational (periodic) fisheries is developed and applied to the sea scallop (Placopecten magellanicus) fishery of the northwest Atlantic. Rotational fishing slightly increases both yield- and biomass-per-recruit for sea scallops at FMAX. These quantities decline less quickly when fishing mortality is increased beyond FMAX than when fishing is at a constant rate. The improvement in biomass-per-recruit appears to be nearly independent of the selectivity pattern but increased size-at-entry can reduce or eliminate the yield-per-recruit advantage of rotation. Area closures and rotational fishing can cause difficulties with the use of standard spatially averaged fishing mortality metrics and reference points. The concept of temporally averaged fishing mortality is introduced as one that is more appropriate for sedentary resources when fishing mortality varies in time and space.

Wadge Bank trawl fishery studies. Pt. 2. The effect of trawling on the catch per hour from 1945 to 1960

The object of this series of papers has been given in Part 1 (see Additional informations for details) which deals with the first known commercial fishery on the Wadge Bank from 1928 to 1935. There is no recorded trawling on the Bank between 1936 and 1944. This paper deals with the changes in the total catch (i.e. all species combined) per hour of trawling in relation to the changes in fishing intensity from 1945, when the present trawling activities started, to 1960. The effect of trawling on individual categories or varieties will be presented later.

Growth, mortality and yield-per-recruit of Copadichromis likomae (Cichlidae) in Lake Niassa, Mozambique

Analysis of the length-frequency data on Copadichromis likomae (Cichlidae) from Lake Niassa, Mozambique, suggests an asymptotic length of SL∞=14 cm associated with a K value of 0.93 yearˉ¹. Total and natural mortalities were estimated as 3.2 yearˉ¹ and 1.9 yearˉ¹, respectively. Yield-per-recruit analysis suggests that E=0.36 in this fishery.

Estimating the population density of prawns by the use of catch per effort data from prawn trawlers at Chilaw

The penaeid prawns of Sri Lanka from estuaries and sea are an important commercial fishery resource. This resource has been exploited over the last century or more by local fishermen using indigenous fishing gear from locally sail-driven or oar-driven fishing crafts. In more recent times, the Fisheries Research Division of the Department of Fisheries undertook surveys of the seas and lagoons of Sri Lanka with a view to ascertain whether any unexploited resources of prawns existed. These publications deal with the species composition, biology, distribution and abundance in the lagoons and inshore waters of Sri Lanka.

Increased capacity per unit-cost by oversampling

It is demonstrated that doubling the sampling rate recovers some of the loss in capacity incurred on the bandlimited Gaussian channel with a one-bit output quantizer. © 2010 IEEE.

Derivation of a vector model for a Brushless Doubly-Fed Machine with multiple loops per nest

The paper presents a vector model for a Brushless Doubly-Fed Machine (BDFM). The BDFM has 4 and 8 pole stator windings and a nested-loop rotor cage. The rotor cage has six nests equally spaced around the circumference and each nest comprises three loops. All the rotor loops are short circuited via a common end-ring at one end. The vector model is derived based on the electrical equations of the machine and appropriate vector transformations. In contrast to the stator, there is no three phase circuit in the rotor. Therefore, the vector transformations suitable for three phase circuits can not be utilised for the rotor circuit. A new vector transformation is employed for the rotor circuit quantities. The approach presented in this paper can be extended for a BDFM with any stator poles combination and any number of loops per nest. Simulation results from the model implemented in Simulink are presented. © 2008 IEEE.

Perovskite-Like Mixed Oxides (LaSrMn1-x Ni (x) O4+delta, 0 a parts per thousand currency sign x a parts per thousand currency sign 1) as Catalyst for Catalytic NO Decomposition: TPD and TPR Studies

Catalytic NO decomposition on LaSrMn1-x Ni (x) O4+delta (0 a parts per thousand currency sign x a parts per thousand currency sign 1) is investigated. The activity of NO decomposition increases dramatically after the substitution of Ni for Mn, but decreases when Mn is completely replaced by Ni (x = 1.0). The optimum value is at x = 0.8. These indicate that the catalytic performance of the samples is contributed by the synergistic effect of Mn and Ni. O-2-TPD and H-2-TPR experiments are carried out to explain the change of activity. The former indicates that only when oxygen vacancy is created, could the catalyst show enhanced activity for NO decomposition; the latter suggests that the best activity is obtained from catalyst with the most matched redox potentials (in this work, the biggest Delta T and Delta E values).

Il Sistema di Revenue Management strumento per lo sviluppo turistico sostenibile delle destinazioni

Businesses interact constantly with the environment, realizing several and heterogeneous exchanges. Organizations can be considered a system of different interests, frequently conflicting and the satisfaction of different stakeholders is a condition of success and survival. National and international literature attempts to explain the complex connection between companies and environment. In particular, the Stakeholder Theory considers crucial for businesses the identification of different stakeholders and their involvement in decision-making process. In this context, profit can not be considered the only purpose of companies existence and business aims become more numerous and different. The Stakeholder Theory is often utilized as framework for tourism studies, in particular in Sustainable Tourism Development research. In fact, authors consider sustainable the tourism development able to satisfy interests of different stakeholders, traditionally identified as local community and government, businesses, tourists and natural environment. Tourism businesses have to guarantee the optimal use of natural resources, the respect of socio-cultural tradition of local community and the creation of socio-economic benefits for all stakeholders in destinations. An obstacle to sustainable tourism development that characterizes a number of destinations worldwide is tourism demand seasonality. In fact, its negative impact on the environment, economy and communities may be highly significant. Pollution, difficulties in the use of public services, stress for residents, seasonal incomes, are all examples of the negative effects of seasonality. According to the World Tourism Organization (2004) the limitation of seasonality can favour the sustainability of tourism. Literature suggests private and public strategies to minimize the negative effects of tourism seasonality, as diversification of tourism products, identification of new market segments, launching events, application of public instruments like eco-taxes and use of differential pricing policies. Revenue Management is a managerial system based on differential pricing and able to affect price sensitive tourists. This research attempts to verify if Revenue Management, created to maximize profits in tourism companies, can also mitigate the seasonality of tourism demand, producing benefits for different stakeholders of destinations and contributing to Sustainable Tourism Development. In particular, the study attempts to answer the following research questions: 1) Can Revenue Management control the flow of tourist demand? 2) Can Revenue Management limit seasonality, producing benefits for different stakeholders of a destination? 3) Can Revenue Management favor the development of Sustainable Tourism? The literature review on Stakeholder Theory, Sustainable Tourism Development, tourism seasonality and Revenue Management forms the foundation of the research, based on a case study approach looking at a significant destination located in the Southern coast of Sardinia, Italy. A deductive methodology was applied and qualitative and quantitative methods were utilized. This study shows that Revenue Management has the potential to limit tourism seasonality, to mitigate negative impacts occurring from tourism activities, producing benefits for local community and to contribute to Sustainable Tourism Development.