Drifting objects as habitat for pelagic juvenile fish off New South Wales, Australia

2004 ◽  
Vol 55 (7) ◽  
pp. 675 ◽  
Author(s):  
Tim Dempster ◽  
Michael J. Kingsford
Keyword(s):  
New South ◽  
Juvenile Fish ◽  
New South Wales ◽  
Weather Conditions ◽  
Small Fish ◽  
Drift Algae ◽  
Odour Source ◽  
South Wales ◽  
Fish Aggregation ◽  
Drifting Algae

The importance of drifting objects to small juvenile pelagic fish was investigated off the coast of New South Wales, Australia. Distance-related and temporal patterns in the distribution of clumps of drifting algae were investigated with 5000 m2 transects at five distances from shore (0.1, 0.5, 1, 5 and 10 km), two to three times per season for 2 years. Juvenile fish associated with drift algae were collected. Clumps of algae, predominantly Sargassum spp., were most abundant in spring, which coincided with the highest abundance of alga-associated post-flexion juvenile fish. Drift algae were also most abundant close to shore, probably due to the proximity to source and the dominant onshore winds. Fish were quickly attracted to drifting artificial objects (fish aggregation device; FADs), although the magnitude of attraction varied greatly among days. The relative abundance of small fish in open waters available to colonise FADs and differing weather conditions may explain much of this variability. More fish colonised FADs with an odour source than unscented control FADs, indicating small fish may use chemical cues to locate drifting structures. We conclude that juvenile fish actively seek drifting objects as pre-settlement habitat, which may reduce predation and enhance settlement opportunities.

The Relation Between the Food of the Australian Barracouta, Thyrsites atun (Euphrasen), and Recent Fluctuations in the Fisheries

1957 ◽  
Vol 8 (1) ◽  
pp. 29 ◽  
Author(s):  
M Blackburn
Keyword(s):  
Population Distribution ◽  
New South ◽  
New South Wales ◽  
South Australia ◽  
Downward Trend ◽  
Small Fish ◽  
Fish Diet ◽  
Upward Trend ◽  
Independent Evidence ◽  
South Wales

The diet of surface-swimming Australian barracouta was studied from over 10,000 stomachs. The principal prey organisms in Bass Strait are the euphausiid Nyctiphanes australis Sars, the anchovy Engraulis australis (White), and young barracouta, in that order; and in eastern Tasmania Nyctiphanes, Engraulis, and the sprat Clupea bassensis McCulloch, in that order. The pilchard Sardinops neopilchardus (Steindachner) is not an important item of the diet in these regions although it is so in New South Wales, South Australia, and Western Australia. The jack mackerel Trachurus declivis Jenyns is a significant item in eastern Tasmania and New South Wales but not in Bass Strait. These and other features of the fish diet of the barracouta reflect actual availability of the various small fish species in the waters. Barracouta eat Nyctiphanes by herding them into dense masses (or finding them already concentrated) and swallowing them. The movements of the anchovy make it unavailable to Bass Strait and eastern Tasmanian barracouta for much of the summer and autumn period, when the barracouta are thus dependent upon Nyctiphanes for the bulk of their food. A close positive relationship between the availability of barracouta and Nyctiphanes might therefore be expected at those seasons. There is evidence of such a relationship between mean availability (catch per boat-month) of barracouta and mean percentage of barracouta stomachs containing Nyctiphanes, at those seasons, from year to year. For southern Victorian coastal waters both show a downward trend from 1948-49 to 1950-51 and then an upward trend to 1953-54; for eastern Tasmania both show a downward trend (for autumn only) from 1949-50 through 1952-53. The records of catch per boat-month furnish independent evidence that the main variations in this index were effects of availability (population distribution or behaviour) rather than abundance (population size), at least for southern Victoria. It is therefore considered that when scarcity of barracouta occurs in summer and autumn in the coastal fishing areas it may be due to scarcity of Nyctiphanes, forcing the fish to go offshore for this food which is known to be available there. This would take the fish out of range of the fishermen.

The seasonality of hip fracture and its relationship with weather conditions in New South Wales

2010 ◽  
Vol 19 (1) ◽  
pp. 76-80 ◽  
Author(s):  
Edith M.C. Lau ◽  
Bill G. Gillespie ◽  
Lisa Valenti ◽  
Dianne O'Connell
Keyword(s):  
Hip Fracture ◽  
New South ◽  
New South Wales ◽  
Weather Conditions ◽  
South Wales

Stream use by the large-footed myotis Myotis macropus in relation to environmental variables in northern New South Wales.

2006 ◽  
Vol 28 (1) ◽  
pp. 15 ◽  
Author(s):  
J. Anderson ◽  
B. Law ◽  
C. Tidemann
Keyword(s):  
Data Base ◽  
Environmental Variables ◽  
New South ◽  
New South Wales ◽  
North Coast ◽  
Small Fish ◽  
Field Surveys ◽  
North East ◽  
South Wales ◽  
Myotis Myotis

The large-footed myotis (Myotis macropus) feeds by trawling aquatic invertebrates and small fish from water surfaces, but little is known about what types of streams are used. We investigated habitat use by M. macropus in northern New South Wales (NSW) by analysing data-base records, conducting field surveys and assessing environmental variables on or near waterways. A GIS comparison of 222 data-base records of M. macropus with broad environmental patterns indicated that most records were near large and permanent waterways at low elevations, in flat or undulating terrain, usually surrounded by vegetation. Three different field surveys were carried-out. First, 25 waterways on the NSW mid-north coast were stratified into five size classes and sampled (December 1996-January 1997) using harp traps and ultrasonic detectors. Just two captures and 20 passes were recorded. No M. macropus were detected on either the smallest or largest waterways, although the latter may have been under-sampled due to their broad expanse. Records of M. macropus were significantly associated with larger, more permanent waterways (when the largest size class was omitted). Non-metric multi-dimensional scaling of sites, described by their environmental attributes, failed to separate sites on the basis of presence/absence of M. macropus. The second survey (February 1998) targeted 25 sites on waterways within 10 km of a known roost in Kerewong State Forest. Twenty-eight passes were recorded, all confined to just three sites on Upsalls Creek, a large 4th order stream. The third survey (February 2000) investigated the use of adjacent riparian vegetation in the vicinity of the Kerewong roost. At each of 12 sites, one detector was placed on the stream, one 10 m from it and a third 20 m into adjacent vegetation. An average of 11 M. macropus passes per night was recorded over streams (total passes = 273), whereas no passes were recorded in adjacent vegetation. We conclude that M. macropus is sparsely dispersed across streams in forests of north-east NSW and that they are most likely to be recorded on large streams in the lower end of catchments. Management implications for timber production forests include redirecting effort from pre-logging surveys to monitoring the changing status of M. macropus over time, especially at day roosts where local populations are concentrated.

Monitoring bait removal in vertebrate pest control: a comparison using track identification and remote photography

2003 ◽  
Vol 30 (1) ◽  
pp. 29 ◽  
Author(s):  
Alistair S. Glen ◽  
Chris R. Dickman
Keyword(s):  
Pest Control ◽  
New South ◽  
New South Wales ◽  
Weather Conditions ◽  
Inexpensive Method ◽  
South Wales ◽  
Vertebrate Pest ◽  
Remote Photography ◽  
Vertebrate Pest Control

The removal of non-toxic fox baits was monitored simultaneously using identification of tracks in sand plots and an inexpensive method of remote photography. During 1126 bait-nights carried out using both methods at sites in the central and northern tablelands of New South Wales, 106 baits were removed by a variety of target and non-target animals. Whereas the results of sand plots may be inaccurate or unreliable, particularly during poor weather conditions, remote photography provides results that are less open to misinterpretation.

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