Rebecca R. McIntosh

Dietary analysis of regurgitates and stomach samples from free-living Australian sea lions

Dietary remains recovered from Australian sea lion (Neophoca cinerea) digestive tracts and regurgitate samples from Seal Bay (Kangaroo Island, South Australia) were used to identify prey species consumed. Four of eight digestive tracts collected (50%) contained prey items located only in the stomach. On the basis of biomass reconstruction of cephalopod prey remains, octopus contributed 40% of the biomass in the samples, giant cuttlefish (Sepia apama) contributed 30% and ommastrephid squids contributed 14% biomass. The remains of several fish species were found in the samples: leatherjacket (Monocanthidae), flathead (Platycephalus sp.), swallowtail (Centroberyx lineatus), common bullseye (Pempheris multiradiata), southern school whiting (Sillago flindersi) and yellowtail mackerel (Trachurus novaezelandiae). Southern rock lobster (Jasus edwardsii) and swimming crab (Ovalipes australiensis) carapace fragments, little penguin (Eudyptula minor) feathers and bones and shark egg cases (oviparous species and Scyliorhinidae sp.) were also identified.

Drivers and annual estimates of marine wildlife entanglement rates: A long-term case study with Australian fur seals

Methods of calculating wildlife entanglement rates are not standardised between studies and often ignore the influence of observer effort, confounding comparisons. From 1997-2013 we identified 359 entangled Australian fur seals at Seal Rocks, south-eastern Australia. Most entanglement materials originated from commercial fisheries; most frequently entangling pups and juveniles. Using Generalized Additive Mixed Models, which incorporated observer effort and survey frequency, we identified that entanglements were observed more frequently amongst pups from July to October as they approached weaning. Neither the decline in regional fishing intensity nor changing seal population size influenced the incidence of entanglements. Using the models, we estimated that 302 (95% CI=182-510) entangled seals were at Seal Rocks each year, equivalent to 1.0% (CI=0.6-1.7%) of the site population. This study highlights the influence of observer effort and the value of long-term datasets for determining the drivers of marine debris entanglements.

Estimating pup production in a mammal with an extended and aseasonal breeding season, the Australian sea lion (Neophoca cinerea)

Abstract Context. The Australian sea lion population at Seal Bay Conservation Park, South Australia, was estimated to be declining at a rate of 1.14% per breeding season, on the basis of maximum counts of live pups in each of 13 breeding seasons (Shaughnessy et al. 2006). The reliability of the pup-production estimates used to identify this decline is uncertain. Aims. Our aims were to obtain representative and repeatable estimates of pup production and to assess the current rate of decline. Methods. We compared four estimates of pup abundance over five breeding seasons (2002–03, 2004, 2005–06, 2007, 2008–09), including the count of cumulative new births, the maximum live-pup count, the number of pups given passive integrated transponder (PIT) tags, and mark–recapture methods using the Petersen estimate. Key results. A total of 90% of pup births occurred over a mean of 124 days (s.d. = 14). Final estimates of pup production (from the largest of the four estimation methods used) in the five seasons were 227 (CL 221–239), 288 (CL 273–302), 219 (NA), 260 (CL 254–272) and 268 (CL 268–269). The average estimate of pup mortality was 28.6% (s.d. = 6.3%). The decline in the population at Seal Bay over 17 breeding seasons on the basis of maximum counts of live pups was 0.51% per year or 0.76% per breeding season. However, this trend was not based on best estimates of pup production. On the basis of final estimates for the last five breeding seasons, there is no declining trend. Conclusions. The count of cumulative new births was the most reliable measure of pup production; the Petersen mark–recapture estimate provided a check for accuracy and confidence limits about the estimate. Implications. The actual rate of change and the expected trajectory of the Seal Bay population remain uncertain. Ongoing monitoring is a priority for this site, using the reliable methods of estimating pup production identified in the present study.

Fur seals at Macquarie Island: post-sealing colonisation, trends in abundance and hybridisation of three species

Commercial sealers exterminated the original fur seal population at Macquarie Island in the early 1800s. The first breeding record since the sealing era was not reported until March 1955. Three species of fur seal now occur at Macquarie Island, the Antarctic (Arctocephalus gazella), subantarctic (A. tropicalis) and New Zealand (A. forsteri) fur seal. Census data from 54 breeding seasons in the period 1954–2007 were used to estimate population status and growth for each species. Between the 1950s and 1970s, annual increases in pup production for the species aggregate were low. Between 1986 and 2007, pup production of Antarctic fur seals increased by about 8.8% per year and subantarctic fur seals by 6.8% per year. The New Zealand fur seal, although the most numerous fur seal species on Macquarie Island, has yet to establish a breeding population, due to the absence of reproductively mature females. Hybridisation among species is significant, but appears to be declining. The slow establishment and growth of fur seal populations on Macquarie Island appears to have been affected by its distance from major population centres and hence low immigration rates, asynchronous colonisation times of males and females of each species, and extensive hybridisation.

Effects of human disturbance on productivity of White-bellied Sea-Eagles (Haliaeetus leucogaster)

Abstract Nest productivity among the White-bellied Sea-Eagle (Haliaeetus leucogaster) population on Kangaroo Island (South Australia) was monitored over 11 breeding seasons between 1985 and 1999. Territories were assessed against standardised measures of relative isolation from human disturbance and assigned to Low-, Moderate- or High-disturbance categories. When productivity data were compared between categories, the level of disturbance was found to significantly affect fledging outcomes, with high-disturbance territories having significantly lower fledging success. Of 164 occupied territory-years, 119 (72.6%) were active and fledged 0.8 (mean) young per year. Territories with high-disturbance levels produced eggs less often (65% of territories active cf. 79% active in more isolated locations), fledged fewer young (0.5 young per year cf. 1.1), and had higher rates of nesting failure (46% cf. 13%). These results indicate that to mitigate further Sea-Eagle population decline in South Australia, site-specific habitat management prescriptions, which include buffer-zone refuge provisions, are required to minimise the effects of human activity on breeding outcomes. Such prescriptions need to take into account that, unique to South Australia, most nests are on cliffs in open coastal landscapes with little visual screening over long distance, thus refuge dimensions should be double those prescribed elsewhere for nests in tall forest habitat.

Morphology, sex ratio and cause of death in Australian sea lion (Neophoca cinerea) pups

During a study of the demographics of the Australian sea lion (Neophoca cinerea), the sex ratio and morphology were obtained from 128 pups at Seal Bay Conservation Park over three breeding seasons (2002–03, 2004 and 2005–06). Gross necropsies were also performed. Dead pups were small and young, averaging 8.0 and 7.0 kg in weight, and 75.2 and 71.3 cm in length, for males and females respectively, only 1.8 kg heavier and 6.7 cm longer than newborn pups. There was no sex bias in the dead pups overall or in each cause of death classification. In 49% of mortalities, cause of death could not be inferred from gross necropsy and pups appeared in good condition. In pups in which cause of death was inferred, trauma inflicted by conspecifics was the primary result in both males and females (31.6%), followed by emaciation (10.4%), stillbirth or premature birth (7.6%) and possible shark attack (1.4%). Histopathological examination of tissues and other investigations would be required to determine whether other factors, such as disease or parasitic infection, and pollutant contamination contribute to pup mortality.

Status of small colonies of the Australian sea lion Neophoca cinerea on Kangaroo Island, South Australia

The status of the Australian sea lion Neophoca cinerea at eight sites on Kangaroo Island was assessed using criteria adopted by the National Seal Strategy Group based on numbers of pups counted between 1985 and 2005. Each site was allocated to one of three categories. At the Seal Slide, 1 to 11 pups were born over nine pupping seasons and it is classed as a breeding colony. At four sites (Black Point, Cave Point, Cape Bouguer and North Casuarina Island), small numbers of pups were recorded over two or more seasons, and each is classed as a haul-out site with occasional pupping. At three sites near Cape Bouguer, pups were recorded but each instance was several months after a pupping season began at the large breeding colony at Seal Bay, and pups born there are known to move to other sites. Therefore each of these three is classed as a haul-out site. Because N. cinerea is susceptible to mortality from fishery interactions, is strongly philopatric and that small colonies are especially susceptible to extinct...

Understanding meta-population trends of the Australian fur seal, with insights for adaptive monitoring

Effective ecosystem-based management requires estimates of abundance and population trends of species of interest. Trend analyses are often limited due to sparse or short-term abundance estimates for populations that can be logistically difficult to monitor over time. Therefore it is critical to assess regularly the quality of the metrics in long-term monitoring programs. For a monitoring program to provide meaningful data and remain relevant, it needs to incorporate technological improvements and the changing requirements of stakeholders, while maintaining the integrity of the data. In this paper we critically examine the monitoring program for the Australian fur seal (AFS) Arctocephalus pusillus doriferus as an example of an ad-hoc monitoring program that was co-ordinated across multiple stakeholders as a range-wide census of live pups in the Austral summers of 2002, 2007 and 2013. This 5-yearly census, combined with historic counts at individual sites, successfully tracked increasing population trends as signs of population recovery up to 2007. The 2013 census identified the first reduction in AFS pup numbers (14,248 live pups, -4.2% change per annum since 2007), however we have limited information to understand this change. We analyse the trends at breeding colonies and perform a power analysis to critically examine the reliability of those trends. We then assess the gaps in the monitoring program and discuss how we may transition this surveillance style program to an adaptive monitoring program than can evolve over time and achieve its goals. The census results are used for ecosystem-based modelling for fisheries management and emergency response planning. The ultimate goal for this program is to obtain the data we need with minimal cost, effort and impact on the fur seals. In conclusion we identify the importance of power analyses for interpreting trends, the value of regularly assessing long-term monitoring programs and proper design so that adaptive monitoring principles can be applied.

Looking without landing – using Remote Piloted Aircraft to monitor fur seal populations without disturbance

Technical advances in monitoring devices, specifically drones, are allowing managers and scientists to obtain quality information on ecosystem health with minimal disturbance to ecosystems and the wildlife they support. Temporal and spatial indicators of ecosystem health, such as population size and/or abundance estimates of marine mammals are the basis for our understanding and prediction of ecosystem change. This is critical for the achievement of conservation goals and sustainable natural resources use. Performing surveys to obtain abundance estimates can be logistically demanding and expensive particularly in offshore marine environments, and can cause significant disturbance to wildlife. These constraints may lead to sub-optimal monitoring programs that reduce the frequency and/or precision of surveys at the cost of data quality and confidence in the resulting analyses. Using Remote Piloted Aircraft (RPAs) can be a solution to this challenge. With appropriate testing and ethical consideration; for many situations, RPAs can perform surveys with increased frequency, higher data resolution and less disturbance than typical methods that involve people being present on the ground, thereby enabling more robust programs for monitoring. We demonstrate the process of testing images from RPAs for estimating the abundance of Australian fur seals (Arctocephalus pusillus doriferus) at one of their largest colonies on Seal Rocks, Australia. Two sizes of quadcopter (1400 mm and 350 mm) with different imaging equipment were tested at 40, 60 and 80 m altitude above sea level. We assessed wildlife disturbance levels and optimised a methodology for effective and economical monitoring of this site. We employed commercially available and open-source software for programming survey flights (Drone Deploy), image processing (Agisoft Photoscan and Autopano Giga), data collation and analyses (R and Python). An online portal was developed to facilitate data collection, with the ultimate goal being the engagement of the public as citizen scientists in fur seal counts from RPA images. Preliminary comparisons show that a small RPA at 40 m altitude can produce pup counts 20-32% higher than corresponding ground counts without observable disturbance. The benefits and disadvantages of the RPA trials are discussed, as well as important considerations for those looking to incorporate similar methodologies in