Modelling growth rate of Penaeus monodon Fabricius in intensively managed ponds: effects of temperature, pond age and stocking density

Records of shrimp growth and water quality made during 12 crops from each of 48 ponds, over a period of 6.5 years, were provided by a Queensland, Australia, commercial shrimp farm, These data were analysed with a new growth model derived from the Gompertz model. The results indicate that water temperature, mortality and pond age significantly affect growth rates. After 180 days, shrimp reach 34 g at constant 30 degrees C, but only 15 g after the same amount of time at 20 degrees C. Mortality, through thinning the density of shrimp in the ponds, increased the growth rate, but the effect is small. With continual production, growth rates at first remained steady, then appeared to decrease for the sixth and seventh crop, after which they have increased steadily with each crop. It appears that conservative pond management, together with a gradual improvement in husbandry techniques, particularly feed management, brought about this change. This has encouraging implications for the long-term sustainability of the farming methods used. The growth model can be used to predict productivity, and hence, profitability, of new aquaculture locations or new production strategies.

Literacy leadership and accountability practices: Holding onto ethics in ways that count

Despite the rhetoric of schools serving the needs of specific communities, it is evident that the work of teachers and principals is shaped by government imperatives to demonstrate success according to a set of standard ‘benchmarks’. In this chapter, we draw from our current study of new forms of educational leadership emerging in South Australian public primary schools to explore the ways in which test-based accountability requirements are being mediated by principals in schools that serve high poverty communities. Taking an institutional ethnography approach we focus on the everyday work of a principal and a literacy leader in one suburban primary school to show the complexity of the impact of national testing on practices of literacy leadership. We elaborate on the inescapable textual framings and tasks faced by the principal and literacy leader, and those that they create and modify – such as a common literacy agreement and ‘literacy chats’ between a literacy leader and classroom teacher – in order to ‘hold on to ethics’. We argue that while leaders’ and teachers’ everyday work is regulated by ‘ruling relations’ (Smith, 1999), it is also organic and responsive to the local context. We conclude with a reflection on the important situated work that school leaders do in mediating trans-local policies that might otherwise close down possibilities for engaging ethically with students and their learning in a particular school.