bluuebunny/crossref_metadata_2025 huggingface dataset:
Population ecology of the grooved tiger prawn, Penaeus semisulcatus, in the north-western Gulf of Carpentaria, Australia: growth, movement, age structure and infestation by the bopyrid parasite Epipenaeon ingens
Authors: Somers IF , Kirkwood GP
Published: November 2005

Concurrent trawl surveys and tag-recapture studies carried out in the north-western Gulf of Carpentaria between August 1983 and March 1985 provided a detailed description of the growth, movement and age structure of the population of grooved tiger prawns, Penaeus semisulcatus. Growth curves based on the tag-recapture data were used to interpret the length-frequency data collected from the trawl surveys and to determine the number of year classes present. The length-frequency data pertaining to the 1984 year class provided the basis for an estimate of the longevity of the species and a description of the offshore movement patterns. The effect of infestation by the bopyrid parasite Epipenaeon ingens on growth and movement was also examined. Individuals of P. semisulcatus may live for about 2 years, but in the north-western Gulf of Carpentaria very few survive beyond 18 months. Subadults recruit to the offshore fishing grounds during summer and autumn (November-March) at sizes between 20 and 25 mm carapace length (CL) (between 4 and 6 months). By 18 months of age, males reach a size of about 39 mm CL and females about 50 mm CL. The growth rates of both sexes are affected by the presence of E. ingens: males grow faster and larger, the females slower and smaller, with both sexes attaining a size of around 43 mm CL by 18 months of age. The recruiting year class continues to disperse offshore during autumn (from March to May) in such a way that by winter (June and July), although highest abundance is in depths of 35-40 m, the population extends well beyond the commercial fishery into depths greater than 50 m. Although prawns infested with E. ingens show a similar offshore movement, they do not venture beyond depths greater than about 30 m. The sex ratio within the year class remains at around 1 : 1 from the time of recruitment to about 1 year of age. Thereafter, the percentage of females declines steadily; by about 18 months of age very few prawns remain in the population, and of these only about 25% are female. In contrast, the sex ratio for prawns infested with E. ingens remains at about 1 : 1 throughout.
Stock discrimination by trace-element analysis of otoliths of orange roughy (Hoplostethus atlanticus), a deep-water marine teleost.
Authors: Edmonds JS , Caputi N , Morita M
Published: November 2005

Concentrations of trace elements in sagittal otoliths of orange roughy (Hoplostethus atlanticus) from three areas (off Adelaide, and off the eastern and western coasts of Tasmania) were measured by inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry. Canonical-variate (discriminant) analyses of the concentrations of 10 elements (Ba, Cd, Cu, K, Mg, Na, Pb, S, Sr, Zn) showed that the patterns of element concentrations were specific to the areas where fish were captured. These results suggest that there is little movement of fish between the three areas. The elements that were most important in discriminating between the areas were Mg, Na and S.
Dissolved trace metals and their relationship to major elements in the Manuherikia River, a pristine subalpine catchment in central Otago, New Zealand
Authors: Ahlers WW , Kim JP , Hunter KA
Published: November 2005

The spatial distributions of the dissolved trace metals Cu, Ni, Cd, Zn and Pb and of reactive Hg have been measured in parallel with the major elements Na, K, Mg and Ca and electrical conductivity in three sampling events in the Manuherikia River, New Zealand. The geographical span of the sampling sites ranged from a pristine subalpine upper catchment area through lower altitude sites that are increasingly affected by both natural weathering processes and moderate agricultural and domestic runoff. Major-element concentrations in the upper catchment were at or below the 1% frequency minimum of the spectrum of global river compositions, indicating a highly pristine system. Concen- trations increased steadily downstream to levels similar to world average river water. All trace metals exhibited the same spatial trends as the major ions. Typical upper-catchment concentrations were very low by global standards: Cu (150 ng L-1), Ni (100-150 ng L-1), Cd (8 ng L-I), Zn (150-200 ng L-1), Pb (20-30 ng L-1) and Hg (0.3 ng L-1). Oceanic residence times calculated from the data for Zn (80 000 years) and Cd (230 000 years) for which few reliable estimates have been made, are consistent with observed correlations between the oceanographic distributions of these elements and dissolved silicon or phosphate, respectively.
Reproductive biology of yellowfin tuna in the eastern Australian Fishing Zone, with special reference to the north-western Coral Sea
Authors: McPherson GR
Published: November 2005

Developmental stages of oocyte maturation and degenerative stages of postovulatory follicles in yellowfin tuna from the eastern Australian Fishing Zone of the Coral Sea are described. The time of spawning of yellowfin appeared to be during the late evening and early morning. Final oocyte maturation occurred in less than 24 h; postovulatory follicles could not be identified in ovaries after 24 h. Spawning of yellowfin commenced in the north-western Coral Sea by October and had ceased in the central-western Coral Sea by late February. The duration of spawning appeared to be less protracted in the south-western Coral Sea. The average spawning frequency of female yellowfin in the western Coral Sea was once every 1.54 days. Significant differences in spawning frequency were found between different size classes of yellowfin; larger fish spawned more frequently. The spawning stock of yellowfin in the north-western and central-western Coral Sea could be the major source of recruits for the tuna fisheries off the eastern coast of Australia.
Review of the Australian silverside fishes of the genus Atherinomorus (Atherinidae)
Authors: Ivantsoff W , Crowley LELM
Published: November 2005

Previous studies of the genus Atherinomorus suggested that A. lacunosus was one species with a very wide range over the Indian and Pacific Oceans. Morphology (including osteology) and meristics of many populations of Atherinornorus were studied to test this hypothesis. The results indicate that there are two species pairs of Atherinomorus around the coast of Australia. Each of the four species can be distinguished by the combination of meristic and morphological characters. This study was supplemented with an electrophoretic analysis on a limited collection of fish from the western, northern and eastern coasts of Australia.
Effects of runoff from land clearing and urban development on the distribution and abundance of macroinvertebrates in pool areas of a river
Authors: Hogg ID , Norris RH
Published: November 2005

We examined the effects of runoff from urban land clearing and development on the macroinvertebrate pool fauna of the Murrumbidgee River, Australia, over 1 year. Tuggeranong Creek, which flows through the urban development, often recorded higher instantaneous (storm) discharges than did the Murrumbidgee River. Monitoring of suspended solids during one storm event revealed high concentrations of suspended solids (max. 560 mg L-1) entering the Murrumbidgee River for an 8 h period. Such concentrations were not detected by regular two-monthly sampling, although concentrations were generally higher downstream of Tuggeranong Creek. Analysis of substratum particle size revealed a higher proportion of fine inorganic material (<250 pm) at stations downstream of Tuggeranong Creek, suggesting a settling of fine material discharged during storm events. Number of taxa and macroinvertebrate density were lower at downstream stations. We conclude that the deposition of fine inorganic sediment following storm events, and the resulting change in the composition of the substratum, was the major cause of low invertebrate numbers in pools downstream of the cleared catchment.
The role of science in environmental protection
Authors: Constable AJ
Published: November 2005

A process for developing management procedures that may ensure environmental protection is discussed in light of current problems in conservation of the aquatic environment. This process provides an opportunity for determining clearly the role and objectives of science in environmental protection and deals explicitly with the problems to management of uncertain information. Feedback management procedures are advocated, and these should be developed so that they are sufficiently robust in terms of absolute performance. This is to ensure that the environmental objectives set to safeguard the public interest are likely to be met under feasible worst-case conditions despite incomplete knowledge. Three important principles should be incorporated into these procedures before a proposed activity (e.g. development, exploitation) is allowed to commence: (1) the initial level of the activity should be set commensurate with a high degree of confidence that it is ecologically sustainable, (2) the objectives of the regulatory system should be framed in terms of aspects of the state of the environment that can be estimated robustly, and (3) the regulatory framework should specify what actions are required given the state of the environment as observed through the monitoring programme.
Causality and the choice of measurements for detecting human impacts in marine environments.
Authors: Keough MJ , Quinn GP
Published: November 2005

The choice of biological indicator variables to be measured in detecting human impacts on the environment is a critical one. The usual community-level measures (species richness, diversity) generally have questionable theoretical justification, have no demonstrable causal links to the impact, and are dependent on the taxonomic expertise available. Results from trampling experiments on an intertidal rocky shore demonstrate that these measures are also insensitive in detecting impacts that clearly affected populations of individual species. The need for experimental work that identifies which indicator variables are causally linked to human impacts and therefore which will be useful in monitoring is emphasized.
Statistical power and design requirements for environmental monitoring
Authors: Fairweather PG
Published: November 2005

This paper discusses, from a philosophical perspective, the reasons for considering the power of any statistical test used in environmental biomonitoring. Power is inversely related to the probability of making a Type II error (i.e. low power indicates a high probability of Type II error). In the context of environmental monitoring, a Type II error is made when it is concluded that no environmental impact has occurred even though one has. Type II errors have been ignored relative to Type I errors (the mistake of concluding that there is an impact when one has not occurred), the rates of which are stipulated by the a values of the test. In contrast, power depends on the value of α, the sample size used in the test, the effect size to be detected, and the variability inherent in the data. Although power ideas have been known for years, only recently have these issues attracted the attention of ecologists and have methods been available for calculating power easily. Understanding statistical power gives three ways to improve environmental monitoring and to inform decisions about actions arising from monitoring. First, it allows the most sensitive tests to be chosen from among those applicable to the data. Second, preliminary power analysis can be used to indicate the sample sizes necessary to detect an environmental change. Third, power analysis should be used after any nonsignificant result is obtained in order to judge whether that result can be interpreted with confidence or the test was too weak to examine the null hypothesis properly. Power procedures are concerned with the statistical significance of tests of the null hypothesis, and they lend little insight, on their own, into the workings of nature. Power analyses are, however, essential to designing sensitive tests and correctly interpreting their results. The biological or environmental significance of any result, including whether the impact is beneficial or harmful, is a separate issue. The most compelling reason for considering power is that Type II errors can be more costly than Type I errors for environmental management. This is because the commitment of time, energy and people to fighting a false alarm (a Type I error) may continue only in the short term until the mistake is discovered. In contrast, the cost of not doing something when in fact it should be done (a Type II error) will have both short- and long-term costs (e.g. ensuing environmental degradation and the eventual cost of its rectification). Low power can be disastrous for environmental monitoring programmes.
Statistical power and BACI designs in biological monitoring: comparative evaluation of measures of community dissimilarity based on benthic macroinvertebrate communities in Rockhole Mine Creek, Northern Territory, Australia
Authors: Faith DP , Humphrey CL , Dostine PL
Published: November 2005

As part of investigations into strategies for biological monitoring of mining impacts in the vicinity of the Kakadu Conservation Zone, statistical procedures were evaluated in nearby Rockhole Mine Creek, a site of past mining activities. The BACI design and associated statistical test is based on temporal replication of some measure of difference between paired control and impact areas, and it requires that the difference values meet certain statistical requirements while providing adequate statistical power. In investigating extensions of the BACI design to community-level data, a simple gradient-based model of control and impact sites is described that yields predictions concerning the relative performance of different community dissimilarity measures. Abundance data for benthic macroinvertebrates based on the first 2 years of our study at Rockhole Mine Creek are then used to evaluate the potential statistical power of these alternative dissimilarity measures. The measures vary widely in their statistical power, with the Bray-Curtis measure providing high power over both years.
Environmental impact assessment: the roles of predicting and monitoring the extent of impacts
Authors: Smith MPL
Published: November 2005

Assessment of impact can have at least three meanings: the evaluation, prior to impact, of the loss or alteration of a natural community; the prediction of impact; and the measurement of the extent of impact after it has occurred. Measurement of impact in environmental impact assessment (EIA) for aquatic biota is relatively rare. In most cases, scientists are required to predict impacts without testing whether these predictions hold following development. There are numerous study approaches in EIA that form the basis for predictions. These include a reliance on existing information, snapshot surveys, and surveys conducted over several sampling periods prior to impact. The latter two approaches can be divided into surveys of the impact site alone or surveys of the impact site plus control sites. There also is an issue-oriented approach in which the description of the environment is more closely linked to the predicted physical effects of the proposal. An example is given in which organisms at existing marinas are compared with those at natural sites in an area where a new marina is proposed. While there may be a sound scientific basis for the selection of a particular study approach, there are other considerations such as the cost of the proposal, the legislative framework for EIA, the scale of the proposal, and the attitude of the proponent. It is important that predictions of impact be stated as clearly as possible so that they can be evaluated readily and can facilitate monitoring if required. An area in which monitoring could be of value for improving the accuracy of EIA predictions is in small-scale developments, such as small marinas and maintenance dredging.
Occurrence and influence of bopyrid parasites on female penaeid prawns from coastal waters of central Queensland (Australia)
Authors: Courtney AJ
Published: November 2005

The prevalence of bopyrid isopods, parasitic on penaeid prawn hosts, is recorded for the first time from a central Queensland prawn trawl fishery. The bopyrid parasite Parapenaeon prox. expansus has been recorded for the first time from the red spot king prawn, Penaeus longistylus, and the blue-legged king prawn, Penaeus latisulcatus. Previous unpublished reports of Parapenaeon japonicum parasitizing P. longistylus have also been substantiated. Parasite species were not randomly associated with all prawn species but rather were associated with a single prawn host species or species group. The factors that give rise to such specific host-parasite associations, particularly the host-selective behaviour of the parasite and the habitat preferences of the juvenile prawns, are discussed. Bopyrids had no significant effect on the weight of the prawns, but they did have a significant effect on ovary weight and histology, causing sterility in their hosts. High levels of infestation have been recorded from other fisheries (resulting in reduced spawning potential of the host population), but the low prevalence (0.32%) of bopyrid parasites in central Queensland prawns appears to be so low as not to present a concern at present.
Near-surface mixing in a freshwater lake
Authors: Padman L
Published: November 2005

Mixing rates in the upper 10 m of a freshwater lake during the spring heating season are examined by means of fine-structure temperature profiles. Dissipation rate, eddy diffusivity, and vertical heat flux are estimated from 'Thorpe reordering' of measured temperature profiles, a technique that allows these parameters to be obtained from the energy-containing scales of the turbulence rather than from the much smaller scales at which kinetic energy dissipation and scalar diffusion actually occur. The estimated vertical heat fluxes agree reasonably well with the seasonal variability of the lake's total heat content and with the observed short-term variability in mixed-layer temperature. These results suggest that satisfactory estimates of turbulent vertical diffusivities in the surface mixing layer can be obtained from Thorpe reordering. This technique can be applied to data that are considerably simpler and cheaper to obtain than are the measurements of microscale shear required for the more usual 'dissipation' method. Concurrent measurements of vertically averaged shear from a nearby surface mooring are used to study the use of Richardson numbers as a parameter in diffusion models. It is shown that considerable mixing can occur even when the Richardson number based on vertical and temporal averages of shear and density gradient is much larger than the assumed critical value of O(1). Therefore, in regions where the shear and strain variances evaluated over a fixed vertical scale cannot be related either observationally or by means of modelled spectra to the unresolved high wave-number variances, the use of diffusivity parametrizations based on measured, averaged Richardson numbers cannot be justified.
Characterization of natural organic matter from four Victorian freshwater systems
Authors: Day GM , Beckett R , Hart BT , McKelvie ID
Published: November 2005

The natural organic matter (NOM) from three streams (Redwater Creek, Slip Creek, Myrtle Creek) and one small lake (the Inkpot) in Victoria, Australia, was fractionated by a simplified version of Leenheer's method in which the NOM is separated into two fractions-hydrophobic acid (HFo-A) compounds and total hydrophilic (HE-T) compounds-on the basis of association with XAD-8 resin. Subsequently, the HFo-A fraction was further separated into humic acid and fulvic acid fractions. One sample (Redwater Creek) was also separated into six different fractions by the full Leenheer scheme. Considerable variation was found in the ratio of humic substances (or the HFo-A fraction) to nonhumic substances (or the HFi-T fraction) between the four samples, with ratios ranging from a high of 77:23% for the Inkpot to a low of 20:80% for Slip Creek. Samples with higher NOM concentrations had higher percentages of humic substances. The major differences in the proportions of humic to nonhumic compounds observed for Slip Creek (20:80%) and Myrtle Creek (52:48%) support the hypothesis that the residence time of the water in the catchment (or, more specifically, the contact time between this water and the sediments, soil, vegetation and microbial community) may control the concentration and nature of aquatic NOM. Within the HFo-A, or humic fraction, the ratio of fulvic acids to humic acids was fairly constant for each of the four water samples investigated, being dominated (>80%) by fulvic acids.
Comparison of the macroinvertebrate communities in streams in logged and undisturbed catchments 8 years after harvesting
Authors: Growns IO , Davis JA
Published: November 2005

Changes in lotic macroinvertebrate communities 8 years after logging were examined in two sets of paired catchments (Sutton and Lewin) in south-western Western Australia by using analysis of variance, classification (TWINSPAN), and ordination (semi-strong hybrid multidimensional scaling). Both paired catchments contained an undisturbed stream and a stream where clearfelling had been taken to the stream edges. The Sutton catchment also contained a stream where clearfelling had occurred but a 100 m-wide strip of vegetation had been retained as a buffer zone. Differences in richness and abundance of animals between the undisturbed and clearfelled streams in the two catchments were obscured by differences between the sites within each stream. However, ordination of the samples revealed differences in the composition of the macroinvertebrate communities between the clearfelled and undisturbed streams in both catchments. Underlying environmental gradients that separated the invertebrate communities in the clearfelled streams from those in the undisturbed streams, in ordination space, were conductivity, the amount of coarse and fine particulate organic matter, and a reduction in total nitrogen. In all, 11 macroinvertebrate taxa were found to be associated with the separation of samples from the undisturbed and clearfelled streams, this response probably being due to increases in conductivity within the clearfelled streams. Macroinvertebrate community structure in the buffered stream was different from that in the undisturbed stream but was more similar to the latter than to that in the clearfelled stream. Physical and chemical parameters of the buffered stream were also more similar to those of the undisturbed stream. These results indicated that the 100 m-wide buffer zone appeared to be effective in ameliorating any disturbance due to clearfelling.
Biomass, metabolic rates and feeding of some common reef zoantharians and octocorals
Authors: Sorokin YI
Published: November 2005

The biomass of individual polyps in most common octocorals ranged from 40 to 90 �g C, and the biomass of polyps per 1 g wet weight of colony ranged from 15 to 30 mg C. In the case of zoantharians, the corresponding values were 0.6 mg C and 3.7 mg C g-1 for Palythoa caesia and 9 mg C and 73 mg C g-1 for Zoanthus sociatus. In both octocorals and zoantharians, the percentage ratios of the biomass of zooxanthellae to the biomass of polyps were similar to those in scleractinians: 1.5-4.0%. The rate of photosynthesis ranged from 0.1 to 3.2 mg C g-1 dry weight of colony per day. The ratio of photosynthesis to respiration in most symbiotic octocorals was more than 1 (1.4-2.7); it was less than 1 only in Alcyonium molle and Lobophytum roxasi. Daily respiration in symbiotic octocorals and zoantharians represented 0.6-3.0% of the total biomass of their polyps; in asymbiotic species, it was around 2-5%. Heterotrophic predatory feeding, sedimentary feeding, and feeding on dissolved organic matter were quantified by radiocarbon labelling. The ability to prey on and use different kinds of food varied with taxonomic group. Also, zoantharians and octocorals were much poorer heterotrophic feeders than are scleractinians. By heterotrophic feeding at optimum food concentrations, most zoantharians and octocorals could satisfy 10-100% of their energy requirements (cf. 200-300% for scleractinian corals). The extent of success of zoantharians and octocorals in competition with scleractinians is discussed.
Movement, fishery sector impact, and factors affecting the recapture rate of tagged sand crabs, Portunus pelagicus (L.), in Moreton Bay, Queensland
Authors: Potter MA , Sumpton WD , Smith GS
Published: November 2005

Selected mature male sand crabs (Portunus pelagicus) (6827 individuals with carapace widths of 120-192 mm) were tagged with Floy ED-68BA anchor tags and released in 14 areas of Moreton Bay and adjacent oceanic waters. In all, 1003 tagged crabs (14.7%) were recaptured, with 79% of these recaptured less than 2 km from their release points and 4% recaptured more than 10 km from their release points. Of the total recaptures, 63% were made within 14 days of crabs being released. Commercial pot fishers recaptured the largest proportion (70%) of crabs, whereas recreational fishers and commercial trawl fishers recaptured only 18 and 12% of tagged crabs, respectively. Recapture rates varied from 2 to 59%, depending on location, reflecting a massive spatial heterogeneity of fishing effort. Only 2.6% of recaptured crabs moulted between release and recapture. Crabs that were undamaged at release had twice the recapture rate of damaged crabs (i.e. crabs that had missing appendages), and the probability of recapture increased with crab size. Under laboratory conditions, unmodified Floy FD-68BA tags reduced the short-term survival of male P. pelagicus, possibly because of bacterial infection, and it was concluded that Floy anchor tags were not suitable for field growth studies of P. pelagicus.
Limnological features of coastal-plain wetlands on the Gnangara Mound, Perth, Western Australia
Authors: Wrigley TJ , Rolls SW , Davis JA
Published: November 2005

The Gnangara Mound is an area of elevated sandy soil on the Swan Coastal Plain to the north of
Perth. It constitutes a major groundwater resource for metropolitan Perth. Sixteen wetlands on the
Mound had total phosphorus concentrations of 12-462�g L-1, the high values being attributed to
agricultural and urban activity. Sediment concentrations of total phosphorus and total nitrogen were
61-954 and 1212-16739 �g g-1, respectively. Conductivities were 505-10270 �S cm-1, and pH values
were 3.3-9.3. Only one wetland was highly coloured (79.9 8440 m-1), with an E4/E6 ratio of 4.6.
Chlorophyll a concentrations were 0.01-130.8�g L-1; in wetlands with low gilvin concentrations,
Myxophyceae dominated, whereas wetlands with higher gilvin concentrations had large numbers of
diatoms and Chlorophyceae. The highly coloured wetland had the lowest chlorophyll a concentration
despite high nutrient concentrations, supporting the hypothesis that the consequent reduction in light
or other associated factors are important in maintaining low phytoplankton biomass in dystrophic
wetlands of the region, particularly those on Bassendean sands.
Preliminary observations on the biology of the White Shark, Carcharodon carcharias, in South Australian waters
Authors: Bruce BD
Published: November 2005

The seasonal and geographic distribution of three size categories of white sharks, Carcharodon
carcharias (<250 cm, 250-450 cm, >450 cm), is described for South Australian waters. On the
basis of 217 records, C. carcharias of all sizes were widely distributed throughout the study area
but were most commonly reported in inshore waters less than 15 m deep. Sea surface temperatures
at the report sites ranged from 12 to 24�C. A wide range of prey items was recorded, with teleosts
predominant in sharks less than 250 cm and cetaceans in sharks greater than 320 cm.
The structure of the ovary of a 520 cm white shark was similar to the structures reported for other
oviphagous lamnids. Sex ratios highly favoured females, suggesting some sexual segregation.
Three recaptures out of 22 sharks tagged in 1990-91 have been reported, the recapture points
varying from 18 to 220 km from the release points and the times at liberty ranging from 30 to 78 days.
Movements and associated observations of bait-attracted White Sharks, Carcharodon carcharias: A preliminary report
Authors: Strong WR , Murphy RC , Bruce BD , Nelson DR
Published: November 2005

Basic population parameters and behaviours of great white sharks, Carcharodon carcharias,
were studied during four expeditions to Spencer Gulf, South Australia. In all, 58 white sharks
were observed, ranging in length from about 2.2 to 5.5 m TL (X= 3.7 m TL � 0.7 s.d.); of these
sharks, 32 were subsequently tagged. Many sharks were observed repeatedly, the most
frequently resighted individual being seen on 22 days over a 197-day period spanning two
expeditions. Sharks in the study area were segregated by sex but not by size. Females were
most abundant at 'inshore' islands, whereas males occurred mainly at 'offshore' islands.
Further, there were no marked differences in abundance between summer and winter.
Nine ultrasonic trackings, lasting a maximum of 27.5 h, revealed three general horizontal
movement patterns: downstream circling, island patrolling, and inter-island cruising. Average
rate of movement was 3.2 km h-1 (n = 145 time intervals of 15 min each). Sharks generally
remained near the surface or along the bottom (about 20 m), spending relatively little time in
midwater. Daytime swimming depths were significantly shallower than those at night.
Biology of Tiger Sharks (Galeocerdo cuvier) caught by the Queensland Shark Meshing Program off Townsville, Australia
Authors: Simpfendorfer C
Published: November 2005

The biology of 835 specimens of Galeocerdo cuvier caught between 1964 and 1986 off Townsville,
Australia, was examined. The sharks were caught in a protective meshing programme using both
large mesh gill-nets and set lines. The size at birth was estimated to be 80-90 cm total length, and
females matured at approximately 287 cm total length. Litter sizes ranged from 6 to 56. Breeding
and pupping both appear to occur in summer, with females not breeding every year. Mature females
possibly migrate inshore during late spring and summer to give birth. The sex ratio of juveniles and
adults favoured females, with few adult males being caught. Ontogenic changes in the diet were observed,
with juveniles feeding predominantly on teleosts, sea snakes and birds and adults mostly consuming
teleosts, sea snakes, turtles and crabs. There was no apparent decrease in the population size of
G. cuvier in the Townsville area as a result of the long-term catching of sharks by the protective meshing
programme.
Tagging studies on the Shortfin Mako Shark (Isurus oxyrinchus) in the Western North Atlantic
Authors: Casey JG , Kohler NE
Published: November 2005

Results of an ongoing Cooperative Shark Tagging Program conducted by the National
Marine Fisheries Service (USA) are described. In all, 2459 shortfin mako sharks
(Isurus oxyrinchus) were tagged off the Atlantic coast of North America and in the
Gulf of Mexico in the 28-year period between 1962 and 1989. The sharks were
tagged by volunteer fishers, scientists aboard research vessels, and US Foreign
Fisheries Observers on foreign vessels fishing in US waters. Altogether, 231 recaptures
(9.4% of releases) of these tagged sharks have been reported by fishers from 16 countries.
The maximum time at liberty is 8.2 years, and the maximum straight-line distance between
tag and recapture localities is 2452 nautical miles. One tag was recovered from the
European side of the Mid-Atlantic Ridge. Mako shark distribution and migratory patterns
in relation to water temperature are discussed for the western North Atlantic.
Diets of sharks from estuaries and adjacent waters of the North-eastern Gulf of Carpentaria, Australia
Authors: Salini JP , Blaber SJM , Brewer DT
Published: November 2005

Sharks were collected over 2 years (six field trips) from the offshore prawn trawling grounds in
Albatross Bay (7-45 m depth), from shallow (< 5 m) nearshore waters, and from the adjacent
inshore waters of the Embley River estuary. Stomachs from 11 shark species were collected
and analysed gravimetrically (% dry weight). Four species (Carcharhinus cautus, C. dussumieri,
C. tilstoni and Rhizoprionodon acutus) were represented in all three regions. Seven general food
categories (Mollusca, Penaeidae, Brachyura, Stomatopoda, Other Crustacea, Teleostei and Other)
were used to describe their diets. Nearly all sharks were primarily piscivorous, and the teleost diet
is discussed in detail. Hemigaleus microstoma was not piscivorous and cephalopods represented
94.7% of its diet. Teleostei constituted less than 70% of the diet for three other species:
C. amblyrhynchos offshore (64.3% Teleostei, 18.6% Penaeidae, 11.6% Mollusca), C. dussumieri
offshore (52.5% Teleostei, 21.8% Stomatopoda, 10.1% Penaeidae), and R. acutus nearshore
(59.3% Teleostei, 17.6% Cephalopoda, 10.3% Brachyura). Offshore, there was a strong correlation
between estimates of consumed prey biomass and of trawled prey biomass, suggesting that these
sharks feed in a density-dependent manner.
Comparative study of the Genus Isurus (Rafinesque, 1810), and description of a form (Marrajo Criollo) apparently endemic to the Azores
Authors: Moreno JA , Moron JQ
Published: November 2005

Numerous captures of mako sharks (Isurus sp.) are made annually by the Spanish longline fishing
fleet in the north-eastern Atlantic Ocean and the western Mediterranean Sea. Sampling of catches
allowed us to compare the morphology of two species of Isurus (I. Oxyrinchus and I. Paucus) and to
document the variations due to size or sex observed in populations exploited by the different
fisheries. The distinctive features of a form apparently endemic to the Azores ('marrajo criollo')
are defined, and the form's taxonomic identity is discussed. This form is possibly a distinct population
of shortfin mako (I. Oxyrinchus). The presence of longfin mako (I. Paucus) is confirmed in waters off
north-western Morocco, and this species is recorded for the first time off the Iberian peninsula.
Functional aspects of Placoid Scales: A review and update
Authors: Raschi W , Tabit C
Published: November 2005

The function of placoid scales (dermal denticles) is considered along three perspectives.
Firstly, in a historical context, denticles have been modified along several functional lines,
including protection from predators and ectoparasites, reduction of mechanical abrasion,
accommodation of bioluminescent and sensory organs, and reduction of frictional drag.
Each function selects for a unique morphology described herein. Secondly, denticles
characteristic of benthic and/or sedentary sharks are re-examined through an analysis of
15 genera. Generalizations are difficult due to the wide range of variation in crown
morphology and overall scale weight, but individual denticle types do reflect combined
optimal characteristics for both hydrodynamics and protection, tending toward the latter.
Lastly, the relationship between slight variations in regional flow dynamics over the body,
and the potential impact of this relationship on the previously defined hydrodynamic scale
characteristics, is examined in two pelagic carcharhinids. These findings suggest that
along the anterior portion of the body, strong indications of reduced ridge dimensions
(heights and spacings) on the dorsum are present and may be related to water velocity.
Tendon structure of the Caudal Fin in the Blue Sharkd, Prionace glauca
Authors: Keithan ED , Ma JY , Rashi W
Published: November 2005

A qualitative description of the myology of three blue shark (Prionace glauca) caudal fins is presented,
forming the basis for a quantitative analysis of the tendon structure. The primary musculature consists
of dorsal epaxial and ventral hypaxial portions. The average crimp angle of collagen fibres in the
epaxial tendons (14.1-26.8�) is significantly greater (P<0.01) than that in the hypaxial tendons (1.8-14.5�).
Similarly, epaxial tendons exhibit a significantly lower fibrocyte nuclear density (0.02- 0.03 nuclei �m-2)
than do the corresponding hypaxial tendons (0.05-0.08 nuclei �m-2) (P < 0.01).
The greater crimp angle and lower fibrocyte nuclear density in epaxial tendons indicate increased tensile
strength, consistent with the comparatively greater muscular force required to move the upper caudal lobe.
Re-examination of the fine structure of endoskeletal mineralization in Chondrichthyans: Implications for growth, ageing and calcium Homeostasis
Authors: Clement JG
Published: November 2005

This paper presents a review of the literature describing calcium regulation mechanisms of chondrichthyans,
with particular emphasis being given to implications for the nature of the skeleton. A further
review of the literature describing mineralized skeletal tissues explores the many conflicting claims
about the presence or absence of bone in chondrichthyans. The fine structure of axial and appendicular
mineralized tissues from five genera is then described, and evidence is presented to support or refute
the hypotheses of others concerning the presence of bone, turnover in the skeleton, and growth without
resorption.
Demography of the central california population of the Leopard Shark (Triakis semifasciata)
Authors: Cailliet GM
Published: November 2005

Demographic analyses can be quite useful for effectively managing elasmobranch fisheries.
However, they require valid estimates of age-specific mortality and natality rates, in addition
to information on the distribution, abundance, habits and reproduction of the population, to
produce reliable estimates of population growth. Because such detailed ecological information
is usually unavailable, complete demographic analyses have been completed for only four shark
species: the spiny dogfish, Squalus acanthias; the soupfin shark, Galeorhinus australis; the lemon
shark, Negaprion brevirostris; and most recently the sandbar shark, Carcharhinus plumbeus.
In California, reliable estimates of age, growth, mortality, age at maturity, and fecundity are
available only for the leopard shark, Triakis semifasciata. A demographic analysis of this
species yielded a net reproductive rate (Ro) of 4.467, a generation time (G) of 22.35 years,
and an estimate of the instantaneous population growth coefficient (r) of 0.067. If the mean
fishing pressure over 10 years (F= 0.084) is included in the survivorship function, Ro and r
are reduced considerably, especially if leopard sharks first enter the fishery at early ages.
A size limit of 120 cm TL (estimated age 13 years), especially for female sharks, is tentatively
proposed for the leopard shark fishery.
Fishery simulation model for sharks applied to the Gummy Shark, Mustelus antarcticus Gunther, from Southern Australian waters
Authors: Walker TI
Published: November 2005

A dynamic pool simulation model is derived and applied to the gummy shark stock of the
southern shark fishery. Inputs to the model are fishing effort reported by fishers for hooks
and for gill-nets with mesh sizes of 6 inches (152 mm), 7 inches (178 mm) and 8 inches
(203 mm) along with estimates for growth, natural mortality, catchability, hook and gill-net
mesh selectivity, size at maturity and fecundity of females, sex ratio at birth, and length-weight
relationships. Growth is described by the von Bertalanffy equation; hook selectivity is constant
with length for sharks recruited to the fishery; gill-net selectivity is based on the probability
density distribution of the gamma function where selectivity varies with the mesh size of the
gill-nets and the length of the sharks; number of births is related to the proportion of females
mature at each length, and the relationship between number of births and maternal weight is
linear; parturition is annual and time is standardized so that parturition occurs at the beginning
of each year; sex ratio at birth is based on observations of a 1: 1 sex ratio of embryos; and
allometric weight-length is based on the power curve. Natural mortality of recruits, catchability,
reproduction and growth parameters are held constant, but density-dependent natural mortality
of prerecruits is varied in proportion to stock abundance. The model is used to simulate effects
of historical longline fishing effort and gill-net fishing effort for each mesh size on stock biomass,
numbers of sharks in the stock, and numbers of births. The performance of the model is
evaluated by comparing simulated annual catches and the simulated mean weight of sharks
captured with annual catches reported by the fishers and the mean weight of sharks sampled in
commercial landings. Uncertainties surrounding estimates of some of the parameters are discussed.
Notwithstanding its shortcomings, the model indicates that the stock of gummy shark has been
severely reduced and is in danger of further depletion unless immediate action is taken to reduce
the commercial catch.
Preliminary results of a study into the incidental mortality of sharks in Gill-nets in two Tasmanian Shark Nursery Areas
Authors: Williams H , Schaap AH
Published: November 2005

Since the early 1960s, certain sheltered bays and estuaries around Tasmania have been
designated shark nursery areas, where the taking of either the school shark (Galeorhinus galeus)
or the gummy shark (Mustelus antarcticus) has been prohibited. Recent assessments of
Australian stocks of school and gummy sharks indicate that they are close to collapse,
and the management of the fishery has come under review. With respect to shark nursery areas,
concern has focused on the potential rate of incidental mortality of sharks caused by recreational
gill-net fishing and poaching. In 1990, a study was begun in Frederick Henry Bay and Norfolk Bay,
the largest proclaimed shark nursery areas in Tasmania, to estimate recreational net-fishing effort
and incidental captures of sharks. School sharks were caught in waters deeper than 5 m; gummy
sharks and dogfish were caught at all depths. The diversity and relative abundance of shark species
increased with depth, whereas the diversity of teleosts decreased with depth. Most captured school
and gummy sharks were between 1+ and 3+ years of age.
Preliminary estimates of potential incidental mortality demonstrate that gill-netting in depths greater
than 5 m may be a significant source of mortality for both species.
Protection against shark attack in South Africa, 1952-90
Authors: Cliff G , Dudley SFJ
Published: November 2005

Historically, most shark attacks in South Africa have occurred off Natal, where the water is relatively
warm and where there are many holiday resorts. The first shark nets were installed in 1952. This,
followed by the establishment of the Natal Sharks Board and the widespread installation of shark
nets in the 1960s, has reduced the incidence of shark attack considerably. Forty-four kilometres of
permanently maintained nets catch an annual average of 1470 sharks and 536 other animals, which
are largely dolphins, turtles and rays. The impact of netting on both the species caught and the inshore
environment as a whole is not well understood and is a cause for concern. The release from the
nets of live animals, including sharks, and the removal of nets during periods of highest catches may
reduce such impact. Experiments with an increased mesh size are in progress. Tests of an electrical
barrier as an alternative to nets have not been encouraging but are continuing. In the cooler waters to
the south of Natal, where there are no shark nets, a marked increase in the number of shark attacks
has taken place in recent years. There appear to be no plans to expand the netting operations into
those waters.
Growth, age estimation and feeding of captive Sevengill Sharks, Notorynchus cepedianus, at the Monterey Bay Aquarium
Authors: Van Dykhuizen G , Mollet HF
Published: November 2005

Five methods, all based on the von Bertalanffy growth function (VBGF) model, were used with captive
sevengills to characterize growth and to estimate both age and age at sexual maturity. Fabens' method
(MI) gave a high k = 0.25 � 0.04 year-1 and a low L∞= 202 � 13 cm and W∞ = 41 � 11 kg. Determination
of the third VBGF parameter, L0 or W0, requires age to be known.
Reported estimates of size at birth were used to estimate ages of individual sharks. For the
'individual VBGF fit' method (M2), the age axis was fixed by using size at birth. For the 'derivative'
method (M3), a growth rate was calculated from observed size when the sharks were received and size
at birth. The results of either method confirmed that two sharks were first-year class and three sharks
were second-year class when they were received. Both M2 and M3 required the use of a combination
of total length (TL) and weight data via the 'TL-scaled cube root weight' method (M4) to obtain
adequate statistics for individual sharks.
The 'exponential regression' method (M5) was used to predict the sizes and ages of larger and older
sharks. Age at sexual maturity for males was estimated by using L∞ = 225-250 cm and k = 0.174
to 0.132 year-1, which gave 4.3 to 5 years, in good agreement with the age estimated from clasper-length
measurements from a single male. Age at sexual maturity for females was estimated by using
L∞ = 275-300 cm and k = 0.107 to 0.090 year-1, which gave 11-21 years.
Feeding habits have been monitored for captive sevengill sharks since 1985. Pups consumed up to
2% of their body weight (BW) per day, juveniles about 0.6% BW day-1, and adults about 0.2%
BW day-1. Food consumption and, more importantly, total efficiency changed with age. The observed
large food consumption and the observed high total efficiency of pups could be substantiated on the
basis of a theoretical calculation of food intake based on von Bertalanffy growth. Adult sevengills
showed a 'feast or famine' feeding pattern that followed a cycle of 5-7 days and that may have been
influenced by water temperature and previous meal size.
We conclude that growth rates in captivity and in the field are similar, based on the available growth
data and feeding behaviour of sevengills in captivity and in the field.
A new record extending the Southerly distribution of the Shark Ray (Rhina ancylostomus), and notes on the behaviour of the specimen in captivity
Authors: Gordon I
Published: November 2005

A live specimen of Rhina ancylostomus was collected off Forster, New South Wales, Australia (32�10'S,
152�45'E), some 600 km farther south than the species has previously been recorded. The specimen has
been maintained live at the Manly Oceanarium, where information has been gained on some basic
behavioural attributes of this rare elasmobranch.
Capture and transportation of Elasmobranchs, with emphasis on the Grey Nurse Shark (Carcharias taurus)
Authors: Smith MFL
Published: November 2005

Physiological changes manifest during the capture and transportation of elasmobranchs are discussed.
Reference is made to the general adaptation syndrome and to mechanisms of change in concentrations
of blood glucose, blood acid and serum electrolyte. Methods of alleviating these profound changes are
suggested, with emphasis on the capture and transportation of the grey nurse shark (Carcharias taurus).
The hoop method is shown to be a convenient technique for capturing wild grey nurse sharks, and a
combination of ketamine hydrochloride and xylazine hydrochloride, with antagonism by yohimbine
hydrochloride, is found to provide an acceptable regime of transportation anaesthesia. Intravenous
administration of sodium bicarbonate and glucose as well as oxygenation of water in the life-support
system are shown to be valuable methods of alleviating stress-induced blood acidosis.