The effect of stocking density and repeated handling on the growth of juvenile mulloway, Argyrosomus japonicus (Temminck & Schlegel 1843)

The effect of stocking density on the growth of mulloway, Argyrosomus japonicus, was tested with 17 g fish stocked at 4.08, 8.16, or 16.32 kg m⁻³ in 50 l aquaria. Weight checks were carried out every 2 weeks to track performance. Each density treatment was also compared to a nonhandled control group to establish if handling during weight checks influenced the growth of mulloway. Mulloway performed poorly at the lowest density and, under the current experiment conditions, growth did not appear to be negatively affected by regular handling.     

Controlling microbial contamination on beef and lamb meat during processing

SUMMARY The microbiological quality of carcases, meat and environmental surfaces was evaluated in commercial boning rooms processing beef and lamb. There was considerable variation in the level of microbial contamination on both carcases and meat, with counts ranging from less than 20 to 10⁸/cm² on carcases and to 2 times 10⁷/cm² on meat. The level of microbial contamination on meat was influenced by the level of carcase contamination at boning and by the boning process itself. Carcase contamination was the major determinant of microbiological quality, as more than 70% of carcases had microbial counts greater than 10³/cm². Cutting boards were a major source for microbial dissemination during boning, particularly when carcase counts were less than 10³/cm². If carcases were heavily contaminated, the contamination of processing surfaces was irrelevant in determining microbial loads on meat. Where carcase contamination was at low to moderate levels, the contribution of the boning process to the contamination on meat assumed increased significance. Under these conditions, improved sanitation of cutting surfaces in the boning room resulted in a significant reduction in microbial contamination on the surface of meat. These results can form the basis for ensuring that improvements made in carcase management before boning, to improve microbiological quality, will be preserved through attention to cutting board hygiene during boning.     

The value of species rarity in biodiversity recreation: A birdwatching example

Wildlife viewing recreation offers conservationists opportunities for education and generating revenue but can also have detrimental ecological impacts. To manage these opportunities and impacts effectively, a better understanding is needed of what people value in wildlife viewing events. We examine the relationship between species rarity and value for wildlife viewing recreation. We undertook visitor counts of birdwatchers attending rare (vagrant) bird sightings and collected home postcodes to assess the distances these individuals travelled to achieve these sightings. We also undertook visitor counts at common bird viewing locations for comparison. We regressed birdwatcher numbers against rarity, site protection status, time the bird had been on site and day of the week when the count took place. We undertook these analyses for rare bird sightings only, using a continuous measure of rarity, and for both rare and common species combined, using a categorical rarity index. Species rarity was the clearest predictor of visitor numbers in both the analyses. When studying rare birds only, we found the functional form of the relationship between rarity and visitor numbers to be inverse and asymptotic. Individuals also travelled further to see rarer species. However, while exceptional numbers of visitors attended exceptionally rare bird sightings, the marginal value of rarity appeared to be relatively low. Despite the opportunity for revenue raising and education provided by rare bird sightings, a comparison of visitor numbers at sightings inside and outside protected areas showed no evidence that managers of protected areas capitalise on these opportunities.