Effect of changes in hook pattern and size on catch rate, hooking location, injury and bleeding for a number of tropical reef fish species

The Queensland Great Barrier Reef line fishery in Australia is regulated via a range of input and output controls including minimum size limits, daily catch limits and commercial catch quotas. As a result of these measures a substantial proportion of the catch is released or discarded. The fate of these released fish is uncertain, but hook-related mortality can potentially be decreased by using hooks that reduce the rates of injury, bleeding and deep hooking. There is also the potential to reduce the capture of non-target species though gear selectivity. A total of 1053 individual fish representing five target species and three non-target species were caught using six hook types including three hook patterns (non-offset circle, J and offset circle), each in two sizes (small 4/0 or 5/0 and large 8/0). Catch rates for each of the hook patterns and sizes varied between species with no consistent results for target or non-target species. When data for all of the fish species were aggregated there was a trend for larger hooks, J hooks and offset circle hooks to cause a greater number of injuries. Using larger hooks was more likely to result in bleeding, although this trend was not statistically significant. Larger hooks were also more likely to foul-hook fish or hook fish in the eye. There was a reduction in the rates of injuries and bleeding for both target and non-target species when using the smaller hook sizes. For a number of species included in our study the incidence of deep hooking decreased when using non-offset circle hooks, however, these results were not consistent for all species. Our results highlight the variability in hook performance across a range of tropical demersal finfish species. The most obvious conservation benefits for both target and non-target species arise from using smaller sized hooks and non-offset circle hooks. Fishers should be encouraged to use these hook configurations to reduce the potential for post-release mortality of released fish.

The Introduction of Transgenes to Control Blackheart in Pineapple: Biolistics Vs Agrobacterium Transformation, in 'Contributing to a Sustainable Future'

Techniques for the introduction of transgenes to control blackheart by particle bombardment and Agrobacterium co-transformation have been developed for pineapple cv. Smooth Cayenne. Polyphenol oxidase (PPO) is the enzyme responsible for blackheart development in pineapple fruit following chilling injury. Sense, anti-sense and hairpin constructs were used as a means to suppress PPO expression in plants. Average transformation efficiency for biolistics was approximately 1% and for Agrobacterium was approximately 1.5%. These results were considered acceptable given the high regeneration potential of between 80-90% from callus cultures. Southern blot analysis revealed stable integration of transgenes with lower copy number found in plants transformed with Agrobacterium compared to those transformed by biolistics. Over 5000 plants from 55 transgenic lines are now undergoing field evaluation in Australia

A simplified PCR test for early detection of dwarf off-types in micropropagated Cavendish bananas (Musa spp. AAA)

The dwarf somaclonal variant is a major problem affecting micropropagation of the banana cultivar Williams (Musa spp. AAA; subgroup Cavendish). This problem arises from genetic changes that occur during the tissue culture process. Early identification of this problem is difficult and propagators must wait until plants are ex vitro in order to visualise the dwarfism phenotype. In this study, we have improved a SCAR-based molecular diagnostic technique, developed by Damasco et al. [Acta Hortic. 461 (1997) 157], for the early identification of dwarf off-types. We have included a positive internal control in a multiplex PCR and adapted the technique for use with small amounts of fresh in vitro leaf material as PCR template. The control product is a 500 bp fragment from 18S rRNA and is amplified in all tissues irrespective of phenotype. The use of small in vitro leaf material removing the need for genomic DNA extraction.

Damage potential of two Scarab species on groundnut

The damage potential of two phytophagous scarab larvae on groundnut (peanut) yield was determined. Holotrichia serrata, a root and pod feeding species from southern India, was studied in microplots while the damage potential of Heteronyx piceus, a pod feeder from Queensland, Australia, was determined by analysis of on-farm chemical-rate trials. H. serrata larva reduced groundnut yield by an average of 7.52 g/ larva. In crops yielding less and more than 1900 kg ha-1, H. piceus reduced yield by 4.20 g and 1.43 g/ larva, respectively. These damage potential estimates were used to determine provisional economic injury levels (EIL). For H. piceus, the provisional EIL is 1.67 and 4.91 larvae/ row-metre in crops yielding less and more than 1900 kg/ha, respectively. For H. serrata, the provisional EIL is one H. serrata larva in 7.1 m2. As more than 70% of southern India groundnut fields have Holotrichia populations greater than 1 larva in 1.35 m2, more widespread use of chlorpyrifos seed dressing of groundnut is likely to produce regional economic benefits.

A field investigation of solubility and food chain accumulation of biosolid-cadmium across diverse soil types

One of the pathways for transfer of cadmium (Cd) through the food chain is addition of urban wastewater solids (biosolids) to soil, and many countries have restrictions on biosolid use to minimize crop Cd contamination. The basis of these restrictions often lies in laboratory or glasshouse experimentation of soil-plant transfer of Cd, but these studies are confounded by artefacts from growing crops in controlled laboratory conditions. This study examined soil to plant (wheat grain) transfer of Cd under a wide range of field environments under typical agronomic conditions, and compared the solubility and bioavailability of Cd in biosolids to soluble Cd salts. Solubility of biosolid Cd (measured by examining Cd partitioning between soil and soil solution) was found to be equal to or greater than that of soluble Cd salts, possibly due to competing ions added with the biosolids. Conversely, bioavailability of Cd to wheat and transfer to grain was less than that of soluble Cd salts, possibly due to addition of Zn with the biosolids, causing reduced plant uptake or grain loading, or due to complexation of soluble Cd2+ by dissolved organic matter.

Effects of hooking damage and hook type on post-release survival of sand flathead (Platycephalus bassensis)

This study examined post-release survival in sand flathead (Platycephalus bassensis) and whether there were survival benefits from the use of circle hooks over conventional hook patterns. Anatomical hooking location was the major factor contributing to mortality, with an almost 100% survival rate for fish hooked in the lip, mouth or eye (shallow-hooked) compared with around 64% for fish hooked in the throat or gut (deep-hooked). Mortality in deep-hooked fish was generally associated with injuries to vital organs (gills, heart, liver) and survival was significantly lower if bleeding was associated with injury (54% compared with 85% for non-bleeders). Circle hooks resulted in significantly lower deep-hooking rates (1%) compared with conventional hook types (4-9%) and, based on catch rates, were at least as effective as conventional hook patterns. Estimated survival rates for line-caught sand flathead were high, over 99% for circle hooks and between 94 and 97% for conventional hooks. These findings support the efficacy of management strategies based on size and bag limits and the practice of catch-and-release fishing for sand flathead, as well as a potential conservation benefit from the use of circle hooks.

Pest-damage relationships for Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) on vegetative soybean.

The response of vegetative soybean (Glycine max) to Helicoverpa armigera feeding was studied in irrigated field cages over three years in eastern Australia to determine the relationship between larval density and yield loss, and to develop economic injury levels. Rather than using artificial defoliation techniques, plants were infested with either eggs or larvae of H. armigera, and larvae allowed to feed until death or pupation. Larvae were counted and sized regularly and infestation intensity was calculated in Helicoverpa injury equivalent (HIE) units, where 1 HIE was the consumption of one larva from the start of the infestation period to pupation. In the two experiments where yield loss occurred, the upper threshold for zero yield loss was 7.51 ± 0.21 HIEs and 6.43 ± 1.08 HIEs respectively. In the third experiment, infestation intensity was lower and no loss of seed yield was detected up to 7.0 HIEs. The rate of yield loss/HIE beyond the zero yield loss threshold varied between Experiments 1 and 2 (-9.44 ± 0.80 g and -23.17 ± 3.18 g, respectively). H. armigera infestation also affected plant height and various yield components (including pod and seed numbers and seeds/pod) but did not affect seed size in any experiment. Leaf area loss of plants averaged 841 and 1025 cm2/larva in the two experiments compared to 214 and 302 cm2/larva for cohort larvae feeding on detached leaves at the same time, making clear that artificial defoliation techniques are unsuitable for determining H. armigera economic injury levels on vegetative soybean. Analysis of canopy leaf area and pod profiles indicated that leaf and pod loss occurred from the top of the plant downwards. However, there was an increase in pod numbers closer to the ground at higher pest densities as the plant attempted to compensate for damage. Defoliation at the damage threshold was 18.6 and 28.0% in Experiments 1 and 2, indicating that yield loss from H. armigera feeding occurred at much lower levels of defoliation than previously indicated by artificial defoliation studies. Based on these results, the economic injury level for H. armigera on vegetative soybean is approximately 7.3 HIEs/row-metre in 91 cm rows or 8.0 HIEs/m2.

Round scallops and square meshes: a comparison of four codend types on the catch rates of target species and by-catch in the Queensland (Australia) saucer scallop (Amusium balloti) trawl fishery

Concern over the amount of by-catch from benthic trawl fisheries and research into the problem have increased in recent years. The present paper demonstrated that by-catch rates in the Queensland (Australia) saucer scallop (Amusium balloti) trawl fishery can be reduced by 77% (by weight) using nets fitted with a turtle excluder device (TED) and a square-mesh codend, compared with a standard diamond-mesh codend with no TED. This large reduction was achieved with no significant effect on the legal size scallop catch rate and 39% fewer undersize scallops were caught. In total, 382 taxa were recorded in the by-catch, which was dominated by sponges, portunid crabs, small demersal and benthic fish (e.g. leatherjackets, stingerfish, bearded ghouls, nemipterids, longspine emperors, lizard fish, triggerfish, flounders and rabbitfish), elasmobranchs (e.g. mainly rays) and invertebrates (e.g. sea stars, sea urchins, sea cucumbers and bivalve molluscs). Extremely high reductions in catch rate (i.e. ≥85%) were demonstrated for several by-catch species owing to the square-mesh codend. Square-mesh codends show potential as a means of greatly reducing by-catch and lowering the incidental capture and mortality of undersize scallops and Moreton Bay bugs (Thenus australiensis) in this fishery

Diversity and abundance of fungivorous thrips (Thysanoptera) associated with leaf-litter and bark across forest types and two tree genera in subtropical Australia

Leaf-litter thrips were much more common and diverse in dry sclerophyll forest than in wetter forest types in subtropical southeast Queensland, Australia. In dry sclerophyll forest, the species composition of thrips in leaf-litter was strongly differentiated from the thrips fauna associated with bark of the trees Eucalyptus major and Acacia melanoxylon (4 of 34 species in common). The species composition of bark-dwelling thrips was similar across the two tree species and also across two eucalypts with different bark types, Eucalyptus major (flaky) and Eucalyptus siderophloia (rough). The diversity of thrips from the leaf-litter was not differentiated across all of these tree species. Virtually all thrips collected were Phlaeothripidae, subfamilies Idolothripinae and Phlaeothripinae. Idolothripinae were associated almost exclusively with leaf-litter, but Phlaeothripinae were in leaf-litter and bark. The association of fungal-feeding thrips with dry sclerophyll forest raises questions about their ecological requirements and the role they play in nutrient cycling. © 2012 Copyright Taylor and Francis Group, LLC.

Crinkles in connectivity: combining genetics and other types of biological data to estimate movement and interbreeding between populations

Marine species generally have large population sizes, continuous distributions and high dispersal capacity. Despite this, they are often subdivided into separate populations, which are the basic units of fisheries management. For example, populations of some fisheries species across the deep water of the Timor Trench are genetically different, inferring minimal movement and interbreeding. When connectivity is higher than the Timor Trench example, but not so high that the populations become one, connectivity between populations is crinkled. Crinkled connectivity occurs when migration is above the threshold required to link populations genetically, but below the threshold for demographic links. In future, genetic estimates of connectivity over crinkled links could be uniquely combined with other data, such as estimates of population size and tagging and tracking data, to quantify demographic connectedness between these types of populations. Elasmobranch species may be ideal targets for this research because connectivity between populations is more likely to be crinkled than for finfish species. Fisheries stock-assessment models could be strengthened with estimates of connectivity to improve the strategic and sustainable harvesting of biological resources.

Effect of biochar amendment on yield and photosynthesis of peanut on two types of soils

Abstract Biochar has significant potential to improve crop performance. This study examined the effect of biochar application on the photosynthesis and yield of peanut crop grown on two soil types. The commercial peanut cultivar Middleton was grown on red ferrosol and redoxi-hydrosol (Queensland, Australia) amended with a peanut shell biochar gradient (0, 0.375, 0.750, 1.50, 3.00 and 6.00 %, w/w, equivalent up to 85 t ha−1) in a glasshouse pot experiment. Biomass and pod yield, photosynthesis-[CO2] response parameters, leaf characteristics and soil properties (carbon, nitrogen (N) and nutrients) were quantified. Biochar significantly improved peanut biomass and pod yield up to 2- and 3-folds respectively in red ferrosol and redoxi-hydrosol. A modest (but significant) biochar-induced improvement of the maximumelectron transport rate and saturating photosynthetic rate was observed for red ferrosol. This response was correlated to increased leaf N and accompanied with improved soil available N and biological N fixation. Biochar application also improved the availability of other soil nutrients, which appeared critical in improving peanut performance, especially on infertile redoxihydrosol. Our study suggests that application of peanut shell derived biochar has strong potential to improve peanut yield on red ferrosol and redoxi-hydrosol. Biochar soil amendment can affect leaf N status and photosynthesis, but the effect varied with soil type.