Continuous Crayfishing Tests: Pelsart Group, Houtman Abrolhos, Western Australia, 1953

1957 ◽  
Vol 8 (4) ◽  
pp. 476 ◽  
Author(s):  
RW George
Keyword(s):  
Western Australia ◽  
Carapace Length ◽  
Long Distance ◽  
Commercial Catch ◽  
Maximum Production ◽  
Catch Rates ◽  
Intensive Fishing

The continuous crayfishing test at the Pelsart Group, Houtman Abrolhos, conducted in 1948, was repeated in 1953. The numbers of crayfish available within the tested area had been reduced from 90 per haul in 1948 to 37 per haul in 1953. There was also a decrease in the commercial catch in 1953 as compared with that of 1948 in the proportion of 90 to 72; and in the catch per man in the proportion 90 to 66. The ratio of the commercial catch in 1950 (the year of maximum production and one of high fishing intensity) to that of 1953 was 90 to 34. In 1953, there were relatively fewer very small and very large crayfish than in 1948. The effects of the 4 years of intensive fishing between 1948 and 1953 on the composition and the numbers of crayfish available at the Pelsart Group are discussed. The period of the test from March 15 to August 26 was divided into three catch phases, characterized by changes in the catch rates. Except for three long-distance movements of tagged crayfish, movements were limited to a distance of approximately 2 miles. Mating commenced on July 1 and by the end of August the majority of mature females were mated. Spawning commenced on August 22. Few females below a carapace length of 2.9 in. were mated.

Validity of using translucent zones of otoliths to age the pilchard Sardinops sagax neopilchardus from Albany, Western Australia

1996 ◽  
Vol 47 (4) ◽  
pp. 617 ◽  
Author(s):  
WJ Fletcher ◽  
SJ Blight
Keyword(s):  
Western Australia ◽  
Age Groups ◽  
Growth Curves ◽  
Relative Number ◽  
Older Individuals ◽  
Commercial Catch ◽  
Monthly Basis ◽  
Lower Accuracy ◽  
Sardinops Sagax ◽  
Catch Rates

Otoliths (sagittae) of the pilchard (Sardinops sagax neopilchardus) from the Albany region of Western Australia were examined on a monthly basis during 1989 to 1991. When read consecutively, with the month of capture known, a clear annual cycle of an increase in marginal increments to October followed by a decline was recorded. This pattern was, however, severely distorted when samples were re-examined after having been jumbled and the month of capture concealed. Younger age groups (≤3) showed evidence of multiple rings being formed annually, but not in all years or individuals, and this was not evident in older individuals (≥4). Agreement between readings was low (43-53%), especially between different readers. Resultant growth curves showed that males grow to a smaller size (L∞ =164, K = 0.805, Φ = 1.03) than females (L∞ = 174, K = 0.584, Φ= 0.95). Agreement between counts of annuli and ages estimated by using otolith weight and length was only 54% for all individuals, but increased to 76% for individuals assigned the same age by different readers. Given the poorer predictions of future catch rates from the relative number of 2-year-olds in the commercial catch using annuli (implying lower accuracy) and increased complexity in preparation, otolith weights will be the method adopted for future ageing.

Catching characteristics of four fish-trap types on the North West Shelf of Australia

1991 ◽  
Vol 42 (4) ◽  
pp. 369 ◽  
Author(s):  
AW Whitelaw ◽  
KJ Sainsbury ◽  
GJ Dews ◽  
RA Campbell
Keyword(s):  
Species Composition ◽  
Western Australia ◽  
Commercial Catch ◽  
North West ◽  
Fish Trap ◽  
The North ◽  
Significant Difference ◽  
Trap Fishery ◽  
Catch Rates ◽  
North Western

Commercial catch rates for the North West Shelf trap fishery, at up to 10 kg trap-1 h-1, are considerably greater than those reported for similar trap fisheries elsewhere. Two fish-trapping experiments were conducted off Lowendal Island (north-western Australia) to study the catch rates of four trap types (O-, S- and Z-shaped and rotational) and two bait types (pilchard, Sardinops neopilchardus, and emperor, Lethrinus choerorynchus) over various soak times (ranging from 1 to 24 h). Total catches varied significantly with soak time. Catches increased rapidly for the first 3 h, levelled off, and then decreased steadily to 16 h; there was a slight increase at 24 h. The species composition of the catch did not vary significantly with soak time. There was no significant difference in catch rates between trap types. The traps did not appear to cause fish to die by being confined in the traps for extended periods. A fairly large amount of suitable bait (about 4 kg) was necessary for effective trapping of fish. The catch rates of the pilchard bait were significantly higher than those of the emperor bait. Over extended soak times (more than 3 h), pilchard bait was lost at a rate of about 6% h-1. whereas there was no detectable loss of emperor bait.

scholarly journals Female reproductive biology and spawning periodicity of two species of king prawns, Penaeus longistylus Kubo and Penaeus latisulcatus Kishinouye, form Queensland's East Coast Fishery

1988 ◽  
Vol 39 (6) ◽  
pp. 729 ◽  
Author(s):  
AJ Courtney ◽  
MCL Dredge
Keyword(s):  
Egg Production ◽  
East Coast ◽  
Sea Water ◽  
Coastal Region ◽  
Ovary Development ◽  
Commercial Catch ◽  
Ovary Weight ◽  
Species Population ◽  
Spawning Periodicity ◽  
Catch Rates

In the coastal region of central Queensland female red-spot king prawns, P. longistylus, and the western or blue-leg king prawns, P. latisulcatus, had high mean ovary weights and high proportions of advanced ovary development during the winter months of July and August of 1985 and 1986. On the basis of insemination, both species began copulating at the size of 26-27 mm CL, but P. longistylus matured and spawned at a smaller size than P. latisulcatus. Abundance of P. longistylus was generally three to four times greater than that of P. latisulcatus but the latter was subject to greater variation in abundance. Low mean ovary weight and low proportions of females with advanced ovaries were associated with the maximum mean bottom sea-water temperature (28.5�C) for both species. Population fecundity indices indicated that peaks in yolk or egg production (a) displayed a similar pattern for both species, (b) varied in timing from year to year for both species and (c) were strongly influenced by abundance. Generally, sample estimates of abundance and commercial catch rates (CPUE) showed similar trends. Differences between the two may have been due to changes in targeted commercial effort in this multi-species fishery.

Management of Chrysanthemoides monilifera subsp. rotundata in Western Australia

2014 ◽  
Vol 7 (1) ◽  
pp. 190-196 ◽  
Author(s):  
John K. Scott ◽  
Kathryn L. Batchelor
Keyword(s):  
Western Australia ◽  
Native Species ◽  
Initial Step ◽  
Buffer Zone ◽  
Industrial Area ◽  
Long Distance ◽  
Awareness Campaign ◽  
First Time ◽  
Established Population ◽  
Bitou Bush

AbstractOne of Australia's most serious weeds, Chrysanthemoides monilifera subsp. rotundata (bitou bush) was recently found for the first time in Western Australia as a well established population in Kwinana, a major port and industrial area south of Perth, the State's capital. This population is remote from other bitou bush infestations in Australia and had escaped detection despite extensive surveys in the same State for the other subspecies that is present in Australia, Chrysanthemoides monilifera subsp. monilifera (boneseed). The main reasons it went undetected are thought to be the tightly controlled access to this area because of mineral processing and port activities, the unusual invasion route via a heavy industrial area and the morphological similarity to a native species when it is not flowering. Two surveys defined the core population of 1038 plants that are spread along the coast over a 25-ha semi-circle with about a 500-m (1640 ft) diameter. Subsequent surveys of first a 500 m buffer zone and later a 1-km (0.621 mi) buffer found four additional plants, indicating that there is considerable potential for dispersal. We concluded that the survey has not delimited the distribution because of the potential and evidence for long distance dispersal. Cooperation by the various land managers has led to all plants being killed, as an initial step to management of this species. Other steps to be undertaken include an awareness campaign in the area that would need to be surveyed for delimitation of the spatial distribution and seed bank assessment to measure potential dispersal both in space and through time. It remains to be determined what is the best strategic response: eradication or containment.

Relative abundances and size compositions of champagne crabs, Hypothalassia acerba, on two coasts and in different water depths and seasons

2004 ◽  
Vol 55 (7) ◽  
pp. 653 ◽  
Author(s):  
Kim D. Smith ◽  
Norman G. Hall ◽  
Ian C. Potter
Keyword(s):  
West Coast ◽  
Carapace Length ◽  
South Coast ◽  
The South ◽  
The West ◽  
Spatial Partitioning ◽  
Invertebrate Predators ◽  
The Mean ◽  
The Difference ◽  
Catch Rates

Hypothalassia acerba was sampled seasonally using traps at depths of 35, 90, 145, 200, 255, 310 and 365 m on the west and south coasts of Western Australia. Catch rates peaked at depths of 200 m on the west coast and 145 m on the south coast but at similar temperatures of 16.1–17.1°C. The west and south coast catches contained 69% and 84% males respectively. The carapace length of H. acerba declined significantly by 4 mm for each 100 m increase in depth. The maximum carapace length of males was greater than females on the west coast (135 v. 113 mm) and south coast (138 v. 120 mm). Furthermore, after adjustment to a depth of 200 m, the mean carapace lengths of males were greater than females on both the west coast (96.6 v. 94.6 mm) and south coast (101.5 v. 91.4 mm), with the difference on the south coast being significant (P < 0.001). Thus, in summary, (1) distribution was related to depth and temperature; (2) body size was inversely related to water depth; and (3) males grew larger and were caught in greater numbers than females. There was also evidence that the distribution changed slightly with season and of spatial partitioning by H. acerba and other large deep-water invertebrate predators.

scholarly journals Extensive Genetic Connectivity and Historical Persistence Are Features of Two Widespread Tree Species in the Ancient Pilbara Region of Western Australia

Genes ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 863
Author(s):  
Heidi M. Nistelberger ◽  
Rachel M. Binks ◽  
Stephen van Leeuwen ◽  
David J. Coates ◽  
Shelley L. McArthur ◽  
...  
Keyword(s):  
Western Australia ◽  
Tree Species ◽  
The Body ◽  
Genetic Connectivity ◽  
Strong Wind ◽  
Cyclonic Activity ◽  
Genetic Structuring ◽  
Long Distance ◽  
Topographic Features ◽  
History Of

Phylogeographic studies can be used as a tool to understand the evolutionary history of a landscape, including the major drivers of species distributions and diversity. Extensive research has been conducted on phylogeographic patterns of species found in northern hemisphere landscapes that were affected by glaciations, yet the body of literature for older, unaffected landscapes is still underrepresented. The Pilbara region of north-western Australia is an ancient and vast landscape that is topographically complex, consisting of plateaus, gorges, valleys, and ranges, and experiences extreme meteorological phenomena including seasonal cyclonic activity. These features are expected to influence patterns of genetic structuring throughout the landscape either by promoting or restricting the movement of pollen and seed. Whilst a growing body of literature exists for the fauna endemic to this region, less is known about the forces shaping the evolution of plant taxa. In this study we investigate the phylogeography of two iconic Pilbara tree species, the Hamersley Bloodwood (Corymbia hamersleyana) and Western Gidgee (Acacia pruinocarpa), by assessing patterns of variation and structure in several chloroplast DNA regions and nuclear microsatellite loci developed for each species. Gene flow was found to be extensive in both taxa and there was evidence of long-distance seed dispersal across the region (pollen to seed ratios of 6.67 and 2.96 for C. hamersleyana and A. pruinocarpa, respectively), which may result from flooding and strong wind gusts associated with extreme cyclonic activity. Both species possessed high levels of cpDNA genetic diversity in comparison to those from formerly glaciated landscapes (C. hamersleyana = 14 haplotypes, A. pruinocarpa = 37 haplotypes) and showed evidence of deep lineage diversification occurring from the late Miocene, a time of intensifying aridity in this landscape that appears to be a critical driver of evolution in Pilbara taxa. In contrast to another study, we did not find evidence for topographic features acting as refugia for the widely sampled C. hamersleyana.

scholarly journals Improving the quality of information on Scottish anglerfish fisheries: making use of fishers' data

2008 ◽  
Vol 65 (7) ◽  
pp. 1334-1345 ◽  
Author(s):  
H. Dobby ◽  
L. Allan ◽  
M. Harding ◽  
C. H. Laurenson ◽  
H. A. McLay
Keyword(s):  
Temporal Trends ◽  
Poor Quality ◽  
Quality Of Information ◽  
Commercial Catch ◽  
Size Category ◽  
History Of ◽  
Scientific Technical ◽  
Catch Rates ◽  
Management Advice

Abstract Dobby, H., Allan, L., Harding, M., Laurenson, C. H., and McLay, H. A. 2008. Improving the quality of information on Scottish anglerfish fisheries: making use of fishers’ data. – ICES Journal of Marine Science, 65: 1334–1345. In recent years, the International Council for the Exploration of the Sea (ICES) Working Group on the Assessment of Northern Shelf Demersal Stocks has been unable to provide an analytical assessment for anglerfish. One of the reasons for this has been the poor quality of the commercial catch-and-effort data, with ICES and the European Commission’s Scientific, Technical, and Economic Committee for Fisheries (STECF) stressing the need for reliable information on which to base estimates of stock status. In response, and following consultation with the fishing industry, an anglerfish tallybook project was implemented in Scotland as part of a long-term approach to providing better data. Tallybooks are completed on a haul-by-haul basis. Skippers record catches of anglerfish (by size category) and other species where possible, together with information on haul location, duration, and depth. Individual vessel catch rates are calculated and used to provide insights into temporal trends in the stock and the spatial distribution of the fishery. The history of the fishery and management advice are summarized, and an overview of the tallybook project is provided. Catch rates are analysed using a generalized additive modelling approach which incorporates seasonal, annual, spatial, and vessel-dependent effects. The results show increased catch rates between 2006 and 2007.

How reliable are the abundance indices derived from commercial catch–effort standardization?

2009 ◽  
Vol 66 (7) ◽  
pp. 1169-1178 ◽  
Author(s):  
Yimin Ye ◽  
Darren Dennis
Keyword(s):  
Generalized Linear Model ◽  
Observation Error ◽  
Potential Bias ◽  
Catch Per Unit Effort ◽  
Rock Lobster ◽  
Commercial Catch ◽  
Abundance Indices ◽  
Catch Rates ◽  
Power Component ◽  
Stock Abundance

Commercial catch-per-unit-effort (CPUE) data are often standardized to construct indices of stock abundance. The value of such standardization lies in the improvement in the proportionality between the derived index and true abundance. Using the Torres Strait rock lobster ( Panulirus ornatus ) fishery in Australia as an example, we first standardized the commercial CPUE data using a generalized linear model (GLM) and then fitted observation error models to the resulting abundance indices and independent abundance data (as estimated by research diver surveys) to examine the proportionality. While the GLM standardization greatly improved proportionality in comparison with the nonstandardized commercial catch rates, it could produce biased results if the model did not explicitly incorporate variables that had caused changes in fishing efficiency. As most catch–effort standardizations do not model the fishing power component simultaneously, this result may serve as a warning to the potential bias in stock abundance indices extracted from GLMs that are underfitted.

scholarly journals The orientation and migratory dynamics of the western rock lobster, Panulirus cygnus, in Western Australia

2014 ◽  
Vol 71 (5) ◽  
pp. 1052-1063 ◽  
Author(s):  
Simon de Lestang
Keyword(s):  
Large Scale ◽  
Economic Benefits ◽  
Rock Lobster ◽  
Commercial Catch ◽  
Breeding Grounds ◽  
Mean Size ◽  
Catch Rates ◽  
Panulirus Cygnus ◽  
The Impact ◽  
Oceanic Currents

Abstract Large-scale migrations are known to occur in numerous species, and in the case of the Western Rock Lobster, Panulirus cygnus, result in juveniles moving from nursery areas into deeper offshore breeding grounds. In 2008 the Western Rock Lobster fishery reduced harvest rates to increase legal and spawning biomass throughout the fishery, which also allowed greater numbers of lobsters to migrate. Increased lobster migration could potentially reduce biomass in some areas, thus adversely impacting commercial catch rates. Over 20 000 tag–recaptured lobsters were analysed to determine the dynamics underlying migration in this species and to assess the impact reduced harvest rates may have had on catches. This study showed that P. cygnus migration was associated with body size and water depth, and that magnetism and oceanic currents appear to be the most likely guideposts used for orientation. Size at migration varied in a constant fashion along the coast, being larger towards the southern end of the fishery and smallest at the offshore Abrolhos Islands. During the migration period, up to 50% of lobsters at their mean size of migration moved from coastal areas out towards deeper waters (>40 m), whereas <15% of those in deeper water at the same size moved significant distances northward. This behaviour appears to be contranatant, counteracting the downstream redistribution of larvae after their 9–11 month larval life. Reduced harvest rates and catches being focussed onto higher valued sedentary lobsters have allowed more lobsters to migrate. However, the numbers moving between management areas are relatively small, with the biological and economic benefits of fishing at a reduced exploitation rate outweighing losses to catches.

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