Hazard function models to estimate mortality rates affecting fish populations with application to the sea mullet (Mugil cephalus) fishery on the Queensland coast (Australia)

Fisheries management agencies around the world collect age data for the purpose of assessing the status of natural resources in their jurisdiction. Estimates of mortality rates represent a key information to assess the sustainability of fish stocks exploitation. Contrary to medical research or manufacturing where survival analysis is routinely applied to estimate failure rates, survival analysis has seldom been applied in fisheries stock assessment despite similar purposes between these fields of applied statistics. In this paper, we developed hazard functions to model the dynamic of an exploited fish population. These functions were used to estimate all parameters necessary for stock assessment (including natural and fishing mortality rates as well as gear selectivity) by maximum likelihood using age data from a sample of catch. This novel application of survival analysis to fisheries stock assessment was tested by Monte Carlo simulations to assert that it provided un-biased estimations of relevant quantities. The method was applied to data from the Queensland (Australia) sea mullet (Mugil cephalus) commercial fishery collected between 2007 and 2014. It provided, for the first time, an estimate of natural mortality affecting this stock: 0.22 $\pm$ 0.08 year$^{-1}$

Fruitgrowers towards a new approach to enhance biodiversity in organic orchards

In the frame of the project “Arbeitsnetz zur Weiterentwicklung der Anbauverfahren des ökologischen Obstbaus” (BOEL-project Nr. 03OE178) a group of fruitgrowers and advicers started to discuss new measures and new concepts to enhance biodiversity in organic orchards. Strips with flowering plants that can be integrated in the normal mulching system and thus, do not originate vole problems, are actually tested on the farms. Other measures as single bushes at the top and end of the rows are in discussion. If such measures are to be integrated successfully in the practice of organic fruit growing, the impulse must spring from growers themselves and their requirements regarding the different risks must be considered. Otherwise, an acceptance in practice is not very probable. This activites are reported here since we want more people to join us

Codling moth populations less susceptible to CpGV: What about higher concentrations?

In an organic orchard with a codling moth (CM) population less susceptible to CpGV it was tested, whether an increased dosage of CpGV by factor 10 would result in any increased efficacy. The applications were set in shorter than weekly intervals with 10 ml/ha Madex (low dosage plot) and 100 ml/ha Madex (high dosage plot). The higher dosage showed also a better efficacy, espe-cially on the “active damage” (live larvae). The orchard where the experiments were conducted was known to have a less susceptible CM population (2004) although there were no serious CM problems reported by the farmer despite the CM control was done only with CpGV. It was investigated, whether natural antagonists might have been a reason for the absence of serious problems in this orchard. No signs of a strong presence of other antagonists were found but CM the population was increasing very much in the year the ex-periment was conducted (2005). Thus, probably the reason for the absence of CM problems seems to be just a delayed increase of the CM population after the development of a lower susceptibility of CM against CpGV

Codling moth populations less susceptible to CpGV: What about higher concentrations?

In an organic orchard with a codling moth (CM) population less susceptible to CpGV it was tested, whether an increased dosage of CpGV by factor 10 would result in any increased efficacy. The applications were set in shorter than weekly intervals with 10 ml/ha Madex (low dosage plot) and 100 ml/ha Madex (high dosage plot). The higher dosage showed also a better efficacy, especially on the “active damage” (live larvae). The orchard where the experiments were conducted was known to have a less susceptible CM population (2004) although there were no serious CM problems reported by the farmer despite the CM control was done only with CpGV. It was investigated, whether natural antagonists might have been a reason for the absence of serious problems in this orchard. No signs of a strong presence of other antagonists were found but CM the population was increasing very much in the year the experiment was conducted (2005). Thus, probably the reason for the absence of CM problems seems to be just a delayed increase of the CM population after the development of a lower susceptibility of CM against CpGV

Experiences with entomopathogenic nematodes for the control of overwintering codling moth larvae in Germany

Entomopathogenic nematodes were tested for their potential as tool in resistance management of codling moth Cydia pomonella L. in organic fruit growing. In two field tests, the adults emerging from stems treated with nematodes were monitored. In one trial, 90 % of efficacy could be shown. On-farm trials with favourable weather conditions showed an efficacy about 50-60 % on fruit infestation by codling moth in the year following the application. On-farm trials with unfavourable weather conditions showed no results. The favourable weather conditions for the application are discussed with reference to German conditions