scholarly journals A comparison of southern hemisphere breeding stock 'D' humpback whale population estimates from two key locations along the Western Australian coast

2019 ◽  
Author(s):  
Curt Jenner ◽  
Micheline Jenner ◽  
Chandra Salgado Kent ◽  
Phil J Bouchet ◽  
Rebecca Dunlop ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Humpback Whales ◽  
Population Estimates ◽  
Breeding Stock ◽  
North West ◽  
Shark Bay ◽  
Monitoring Strategies ◽  
Current Survey ◽  
Australian Coastline ◽  
Western Australian

This report aims to compare recent population estimates of southern hemisphere breeding stock D humpback whales (Megaptera novaeangliae) based on data collected at two key locations along the Western Australian coastline, namely North West Cape (NWC) and Shark Bay, ~400 km south of NWC. The report additionally investigates the efficacy and practicality of current survey designs, and serves as a reference point for future improvement in whale monitoring strategies (location of surveys, field protocols, etc.).

scholarly journals Southern Hemisphere Breeding Stock D humpback whale population estimates from North West Cape, Western Australia

2019 ◽  
Author(s):  
Chandra Salgado Kent ◽  
Curt Jenner ◽  
Micheline Jenner ◽  
Phil J Bouchet ◽  
Eric Rexstad
Keyword(s):  
Western Australia ◽  
Humpback Whales ◽  
Line Transect ◽  
Independent Observer ◽  
Breeding Stock ◽  
North West ◽  
Shark Bay ◽  
Absolute Measure ◽  
Increase Rate ◽  
Best Fit

Estimates of the abundance of Breeding Stock D humpback whales (Megaptera novaeangliae) are key to the conservation and management of what is thought to be one of the largest populations of the species. Five years (2000, 2001, 2006, 2007 and 2008) of aerial surveys carried out over an eight-year period at North West Cape (Western Australia) using line transect methodology allowed trends in whale numbers to be investigated, and provided a base for comparison with estimates made approximately 400km south at Shark Bay (Western Australia). A total of 3,127 whale detections were made during 74 surveys of the 7,043km 2 study area west of NWC. Pod abundance for each flight was computed using a HorvitzThompson like estimator and converted to an absolute measure of abundance after corrections were made for estimated mean cluster size, unsurveyed time, swimming speed and animal availability. Resulting estimates from the migration model of best fit with the most credible assumptions were 7,276 (CI = 4,993–10,167) for 2000, 12,280 (CI = 6,830–49,434) for 2001, 18,692 (CI = 12,980–24,477) for 2006, 20,044 (CI = 13,815–31,646) for 2007, and 26,100 (CI = 20,152–33,272) for 2008. Based on these data, the trend model with the greatest r 2 was exponential with an annual increase rate of 13% (CI = 5.6%–18.1%). While this value is above the species’ estimated maximum plausible growth rate of 11.8%, it is reasonably close to previous reports of between 10–12%. The coefficient of variation, however, was too large for a reliable trend estimate. Perception bias was also not accounted for in these calculations. Based on a crude appraisal which yielded an estimated p(0) of 0.783 (from independent observer effort, CV = 0.973), the 2008 humpback population size may be as large as 33,300. In conclusion, the work here provides evidence of an increasing Breeding Stock D population, but further surveys are necessary to confirm whether the population is indeed increasing at its maximum rate.

scholarly journals Abundance estimates of Southern Hemisphere Breeding Stock ‘D’ humpback whales from aerial and land-based surveys off Shark Bay, Western Australia, 2008

2020 ◽  
pp. 209-221
Author(s):  
Sharon L. Hedley ◽  
John L. Bannister ◽  
Rebecca A. Dunlop
Keyword(s):  
Southern Hemisphere ◽  
Western Australia ◽  
Aerial Survey ◽  
Humpback Whales ◽  
Line Transect ◽  
Breeding Stock ◽  
Abundance Estimate ◽  
Shark Bay ◽  
Abundance Estimates ◽  
Rate Of Increase

Single platform aerial line transect and land-based surveys of Southern Hemisphere Breeding Stock ‘D’ humpback whales Megaptera novaeangliaewere undertaken off Shark Bay, Western Australia to provide absolute abundance estimates of animals migrating northward along the westernAustralian coast. The aerial survey flew a total of 28 flights, of which 26 were completed successfully, from 24 June–19 August 2008. The landbased survey was undertaken from Cape Inscription, Dirk Hartog Island, Shark Bay, during the expected peak of the whales’ northward migration,from 8–20 July. During the first week of the land-based survey, some double count effort was undertaken to provide information on the numbersof pods missed from the land station. The assumed period of northward migration was 2 June–7 September. Estimated abundance of northwardmigrating whales during that time is 34,290 (95% CI: (27,340–53,350)), representing an annual rate of increase of 12.9% (CV = 0.20) since anestimate of 11,500 in 1999. This estimate is based on an estimate of relative abundance of surface-available whales of 10,840 (8,640–16,860), andan estimated g(0) of 0.32. There were considerable practical difficulties encountered during the land-based survey which reduced the effectivenessof the dual-survey approach for estimating g(0) for the aerial survey. Furthermore only about 15% of whales were estimated to be within the visualrange of the land-based station. Alternative approaches for estimating g(0) from these data are therefore also presented, resulting in considerablyhigher estimates of around 0.6–0.7, and yielding a conservative abundance estimate of 17,810 (14,210–27,720).

scholarly journals GEOGRAPHICAL AND TEMPORAL MOVEMENTS OF HUMPBACK WHALES IN WESTERN AUSTRALIAN WATERS

2001 ◽  
Vol 41 (1) ◽  
pp. 749 ◽  
Author(s):  
K.C.S. Jenner ◽  
M-N.M. Jenner ◽  
K.A. McCabe
Keyword(s):  
Continental Shelf ◽  
General Framework ◽  
Group Iv ◽  
Humpback Whales ◽  
Shark Bay ◽  
Migratory Path ◽  
Migratory Route ◽  
Temporal And Spatial ◽  
Exmouth Gulf ◽  
Western Australian

Through compilation of historical whaling data, together with recent aerial and boat-based survey data, a general framework for the overall peaks of migration has been estimated for the temporal and spatial movements of Group IV humpback whales along the Western Australian coast.The migratory paths of humpback whales along the Western Australian coast lie within the continental shelf boundary or 200 m bathymetry. Major resting areas along the migratory path have been identified at Exmouth Gulf (southern migration only) and at Shark Bay. The northern endpoint of migration and resting area for reproductively active whales in the population appears to be Camden Sound in the Kimberley. A 6,750 square km2 area of the Kimberley region, inclusive of Camden Sound, has also been identified as a major calving ground. The northern and southern migratory paths have been shown to be divergent at the Perth Basin, Dampier Archipelago and Kimberley regions. In all cases the northern migratory route is further off-shore.

Spawning and fecundity of the western king prawn, Penaeus latisulcatus Kishinouye, in Western Australian Waters

1980 ◽  
Vol 31 (1) ◽  
pp. 21 ◽  
Author(s):  
JW Penn
Keyword(s):  
Spawning Season ◽  
Ovary Development ◽  
Southern Population ◽  
Spawning Frequency ◽  
Total Length ◽  
Australian Coastline ◽  
The Individual ◽  
Western Australian

The microscopic and macroscopic changes which occur during ovary development to spawning have been investigated for P. larisulcatus. The latter stages (3 and 4) of development and the act of spawning have been found to be confined to single intermoult periods, with spawning being possible during each of a series of consecutive intermoult periods. Fecundity was found to vary significantly with the size of the individual, with the number of eggs ranging from approximately 105000 (123 mm total length female) to 650000 (217 mm total length female) at each spawning. The use of an index of population fecundity in combination with estimates of spawning frequency to document spawning seasons is discussed. Using the population fecundity method the two northern populations have been shown to have a year round spawning season, with maximum spawning occurring from autumn to spring. while the southern population was shown to have shorter seasons over summer. A relationship between ovary development and temperatures in excess of 17�C is suggested as the probable cause of the differences in duration of spawning seasons along the Western Australian coastline.

The Rediscovery and Distribution of Rumex drummondii (Polygonaceae) in South-Western Australia

1995 ◽  
Vol 43 (4) ◽  
pp. 397 ◽  
Author(s):  
JK Scott ◽  
PB Yeoh
Keyword(s):  
Nature Reserve ◽  
Vascular Plant ◽  
Search Theory ◽  
Biological Control Agents ◽  
Weed Species ◽  
North West ◽  
River Region ◽  
Weedy Species ◽  
Road Verges ◽  
Western Australian

Rumex drummondii Meisn., a south-western Australian endemic vascular plant species recorded from widely separated localities, had not been collected for 46 years and was considered possibly extinct. The methods developed from search theory, which has been used for finding lost people or objects, were applied to finding R. drummondii, starting from previous records. Eleven populations of the species were discovered within a 50 km radius in the Kalgan River and Manypeaks region. A disjunct population of six plants was found in 1992 in a parking area at a crossing of the Moore River, 480 km north north west of the others, but had disappeared by 1994. Surveys in the Gingin Brook and Moore River region and between Kalannie and Kulja, another disjunct record, failed to find further plants. The species occupies temporarily wet depressions, lake edges and roadside excavations and dam edges protected from grazing by sheep; habitats also occupied by congeneric weedy species. The species occurs on road verges and farmland and is known from one nature reserve. The rediscovery of R. drummondii enables it to be included in the assessment of potential biological control agents for related weed species in the genera Emex and Rumex.

New phallodrilines (Annelida: Clitellata: Tubificidae) from Western Australian groundwater

Zootaxa ◽  
2006 ◽  
Vol 1304 (1) ◽  
pp. 31 ◽  
Author(s):  
ADRIAN M. PINDER ◽  
S. M. EBERHARD ◽  
WILLIAM F. HUMPHREYS
Keyword(s):  
Southern Hemisphere ◽  
Western Australia ◽  
West Coast ◽  
The State ◽  
Karst Aquifers ◽  
The West ◽  
Western Australian

Four species of phallodriline tubificids (Clitellata: Tubificidae) from karst aquifers and caves along the west coast of the state of Western Australia are the first records of this subfamily from nonmarine waters in the southern hemisphere. Aktedrilus parvithecatus (Erséus 1978) and Pectinodrilus ningaloo n. sp. occur in anchialine groundwater of Cape Range, along with other taxa of marine affinity. Aktedrilus leeuwinensis n. sp. and Aktedrilus podeilema n. sp. occur in caves of the Leeuwin-Naturaliste Ridge and Perth Basin respectively and are the first taxa of marine lineage to have been collected from these systems.

Accuracy of Pup Classifications and Its Effect on Population Estimates in the Hooded Seal (Cystophora cristata)

1988 ◽  
Vol 45 (4) ◽  
pp. 715-719 ◽  
Author(s):  
G. B. Stenson ◽  
R. A. Myers
Keyword(s):  
Developmental Stages ◽  
Survey Design ◽  
Aerial Survey ◽  
Similar Proportion ◽  
Population Estimates ◽  
Hooded Seal ◽  
Cystophora Cristata ◽  
Current Survey ◽  
Survey Estimates ◽  
Misclassification Rates

Information from the classification of age-specific developmental stages has been used to adjust aerial survey estimates of pup production in a number of species of seals, including the hooded seal (Cystophora cristata). We test the assumption that hooded seal pups were accurately and consistently classified according to developmental stage and examine the consequences of misclassifications upon adjusted population estimates. We determined overall misclassification rates, the effect of survey height on classifications, and interobserver variability. At ice level, misclassifications rates were low (<3%). From an altitude of 30 m, newborn pups could not be classified correctly and misclassification rates for the two other stages of attended pups varied between 6.4 and 21.3%. There was no evidence of an overall bias in classifications or differences among observers although there was a significant interaction between day and stage. Individual pups appear to have been misclassified independently by each observer. Under actual survey conditions, observers classified a similar proportion of pups into each recognizable stage. The misclassification rates we observed did not significantly alter the previous population estimate. Methods for improving the current survey design include modifying classification criteria, providing observers with a period of on-ice training, and reducing the width of survey transects.

Sign in / Sign up

Export Citation Format

Share Document