Gillnet size selectivity of shark and ray species from Queensland, Australia

Gillnets are size-selective fishing gears commonly used by industrial and small-scale fishers, so understanding selectivity can aid fisheries management by identifying suitable mesh sizes to optimize catches of target species while reducing bycatch. Few size selectivity parameters have been estimated for sharks, with even fewer for rays. Size selection parameters were estimated for seven species of sharks and two species of rays from the Queensland East Coast Inshore Finfish Fishery (ECIFF). Size frequency data from a fishery observer program on ECIFF vessels was used to fit a standard size selection model. Mesh size independent parameters, θ1 and θ2, were estimated for each species to define selectivity curves for different mesh sizes for each species. Parameter values were compared with previous studies that used the same method. Estimates of θ1 were similar among species within the same genus, such as Carcharhinus, Rhizoprionodon, and Sphyrna. Anoxypristis cuspidata had the largest θ1 and θ2 values, likely because of its toothed rostrum that affected catchability in gillnets. Our findings can be used for the ECIFF and other gillnet fisheries to aid in mesh size recommendations and risk mitigation

Biology and conservation of elasmobranchs: an introduction to the collection

Elasmobranchs, the taxonomic group comprising sharks, skates and rays, play important roles in society and marine ecology but several species in this subclass are under threat. This collection aims to be an open access hub for articles concerning all areas of elasmobranch biology and conservation. The collection is indefinitely open to further submissions and so will continue to grow as additional articles are added

Reactions of durum wheats to Fusarium pseudograminearum in the Northern grain growing region of Australia

Dissertação de mestrado em Marketing, apresentada à Faculdade de Economia da Universidade de Coimbra, sob a orientação de Arnaldo Coelho.Há quem defenda que o estudo do comportamento do consumidor está demasiado focado na fase de aquisição, deixando para segundo plano a compreensão da origem do desejo do consumidor (Pham, 2013). A cultura influencia a forma como o ser humano vive e se relaciona (Salomon et al., 2013). A literatura já há muito reconheceu que o comportamento do consumidor varia entre culturas. Porém os mecanismos por trás desta variação continuam pouco claros (Parker & Tavassoli, 2000). Esta dissertação pretende aclarar alguns desses mecanismos. O objetivo principal desta dissertação é estudar o impacto da cultura no comportamento do consumidor de uma forma geral. A cultura será avaliada tendo por base a teoria das dimensões culturais de Hofstede (Hofstede, 2003), através da CVSCALE – Individual Cultural Value Scale (Yoo, Donthu, & Lenartowicz, 2010). Os consumidores são parte de uma cultura e a cultura é o sistema global em que todos os outros sistemas estão organizados (Salomon et al., 2013). Relativamente ao comportamento do consumidor pretende-se ter uma visão geral, pelo que serão avaliadas áreas do comportamento do consumidor, já descritas na literatura como sendo influenciadas pela cultura: a compra por impulso (Kacen & Lee, 2002), a atitude face ao luxo (Shukla & Purani, 2012) e a atitude face às promoções (McNeill, 2006). Os resultados dos 385 questionários preenchidos na totalidade por consumidores de Portugal e do Brasil permitiram corroborar a teoria de que a cultura tem impacto no comportamento do consumidor, com relevância diferente dentro de cada área do comportamento do consumidor analisada. Também foram identificados alguns mecanismos que permitem perceber de que forma a cultura exerce influência no comportamento do consumidor

Effect of stripe rust on the yield response of wheat to nitrogen

Nitrogen (N) is the most important fertiliser element determining the productivity of wheat. N nutrition is known to affect the level of stripe rust infection, with higher N associated with increased disease severity. Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a major yield-limiting disease of wheat in Australia. This paper describes experiments designed to investigate the agronomic response to the interaction of various levels of N application and stripe rust severity in wheat varieties differing in response. Experimental plots were established in crop seasons 2006 and 2007 on the Liverpool Plains of northern NSW, Australia. Yield, biomass, grain protein content (GPC) and harvest index (HI) data were recorded. Increased rates of N increased the severity of stripe rust during grain filling. N application also increased yield and GPC in all varieties in both years. Stripe rust reduced the yield of the rust-susceptible wheat varieties, and GPC and proportion of added N recovered in the grain were also reduced in one year but not the other. It was evident from our experiment that stripe rust caused yield loss accompanied by either no change or reduction in GPC, indicating that the total amount of N entering the grain was reduced by stripe rust. The effects of stripe rust on N yield are most likely associated with reduced uptake of N during grain filling

Mortality Estimation

Mortality is an essential parameter in understanding the dynamics of any population and sharks are no exception. Without knowledge of how fast individuals are removed from a population it is impossible to model the population dynamics or estimate sustainable rates of exploitation or other useful management parameters.https://scholarworks.wm.edu/vimsbooks/1024/thumbnail.jp

Using yield response curves to measure variation in the tolerance and resistance of wheat cultivars to Fusarium crown rot

The disease crown rot, caused predominantly by the fungal pathogen Fusarium pseudograminearum (Fp), is a major disease of winter cereals in many regions of the world, including Australia. A methodology is proposed, using response curves, to robustly estimate the relationship between grain yield and increasing crown rot pathogen burdens. Using data from a field experiment conducted in northern New South Wales, Australia in 2016, response curves were derived for five commercial wheat cultivars exposed to six increasing rates of crown rot inoculum, where the rates served to establish a range of crown rot pathogen burdens. In this way, the response curve methodology is fundamentally different from alternate approaches that rely on genetic or environmental variation to establish a range in pathogen burdens over which yield loss relationships are estimated. By manipulating only the rates of crown rot inoculum and thus pathogen burden directly, the number of additional confounding factors and interactions are minimised, enabling the robust estimation of the rate of change in yield due to increasing crown rot pathogen burdens for each cultivar. The methodology revealed variation in the rate of change in yield between cultivars, along with the extent of crown rot symptoms expressed by the cultivars. Variation in the rate of change in yield between cultivars provides definitive evidence of differences in the tolerance of commercial Australian wheat cultivars to crown rot caused by Fp, while variation in the extent of crown rot symptoms signifies differences in the resistance of the cultivars to this disease. The response curve methodology also revealed variation in how the different mechanisms of tolerance and resistance act to limit yield losses due to crown rot for different cultivars