In order to assess seasonal and spatial changes in diet, the δ 15 N and δ 13 C signatures of vibrissae from leopard seals Hydrurga leptonyx obtained from Prydz Bay, Eastern Antarctica, were compared with those of a captive seal on a known diet. Using the isotopic signatures of known prey, and those revealed by the assimilation rates of vibrissae, we constructed trophic models to estimate diet composition. Assuming that current diet was reflected only in the actively growing portion of the vibrissae, the latter were sectioned. Each section was then analysed independently. Two methods of analysis of the vibrissae isotopic data were compared in order to ascertain the best analytical approach to these data. A simple linear model and a von Bertalanffy growth model were used to estimate section age and vibrissae growth rates. The age predictions of the von Bertalanffy growth model allowed the existence of repeated seasonal oscillations in both δ 15 N and δ 13 C values. Temporal variations in stable isotope ratios consistent with changes in source of feeding (inshore vs. offshore) and prey types were identified in the Antarctic leopard seals, but not in the captive seal. This preliminary study has possible implications for the use of vibrissae to track dietary changes over time and may serve as a tool for investigating foraging preferences of highly mobile or migratory pinniped species.KEY WORDS: Leopard seal · Stable isotope · Vibrissae · von Bertalanffy · Antarctic · Prey switching Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 305: [249][250][251][252][253][254][255][256][257][258][259] 2005 al. 2004). Changes along the length of whale baleen have provided an isotopic record of seasonal variation in the location of feeding (Best & Schell 1996, Hobson & Schell 1998, Lee et al. 2005) and diet (Schell et al. 1989, Hobson & Schell 1998. Vibrissae may be a useful tissue for isotopic analysis and the study of longterm and seasonal dietary changes. Vibrissae lengths may be transformed into measurements of time, which can then be related to isotopic ratios.Growth rates have been determined for a number of pinniped species using dated vibrissae. Harbour seal vibrissae growth rates were irregular (Hirons et al. 2001) or variable (Zhao & Schell 2004), while growth rates in the case of grey seals Halichoerus grypus varied according to the length and age of the vibrissae and involved asynchronous shedding and discontinuous replacement (Greaves et al. 2004). Conversely, Steller sea lions Eumetobias jubatus displayed more consistent growth and annual retention of their vibrissae (Hirons et al. 2001). Greaves et al. (2004) suggested that vibrissae growth follows a von Bertalanffy growth curve.This study aims to transform vibrissae lengths into time lines using both a simple linear and von Bertalanffy growth model. With information gained through stable carbon and nitrogen isotope analysis of sequentially segmented vibrissae, their potential as indicators of seasonal cha...

We immobilized 200-550-kg leopard seals (Hydrurga leptonyx) on sea ice in Prydz Bay, Antarctica (68"25'S, 77'10'E) between November 1997 and February 2000. Midazolam (0.18-0.27 mgikgfi pethidine (1 .O-1.5 mgikg) was administered by dart to 16 leopard seals. Unpredictable immobilization, poor airway maintenance, and our inability to fully assess the suitability of flumazenil (0.003-0.01 mg/kg), naloxone (0.01-0.013 mgikg), and naltrexone (0.05-0.12 mgikg) as reversal agents limited suitability of midazolam/ pethidine. Tiletamineizolazepam 1:l (0.5-1.5 rng/kg) was, therefore, adrninistered to 19 leopard seals. It produced faster induction (19 ? 3 min), more effective and reliable response to dose (rank correlation: r,r = 0.88, n = 18), and better pulmonary ventilation and faster return of cognitive function upon recovery, in comparison to midazolam/pethidine. Best results were achieved with tiletamineizolazepam (1.2-1.4 mgikg) which safely immobilized seven of nine seals for 20-30 min. Entry to the water upon darting was minimized, but not eliminated, by the use of lightweight air-pressurized darts and a thorough knowledge of leopard seal behavior.The leopard seal (Hydmrga leptonyx) is an antarctic phocid of up to 650-kg body mass, which rests on pack or fast ice, usually within 25 m of the water. Collection of blood, biopsies, and morphometric data, and attachment of satellite-linked time depth recorders (SLTDRs) requires reliable, safe, and complete chemical restraint with rapid, smooth induction and recovery, and min-48 3

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Australian fur seals breed on thirteen islands located in the Bass Strait, Australia. Land access to these islands is restricted, minimising human presence but boat access is still permissible with limitations on approach distances. Thirty-two controlled noise exposure experiments were conducted on breeding Australian fur seals to determine their behavioural response to controlled in-air motor boat noise on Kanowna Island (39°10′S, 146°18′E). Our results show there were significant differences in the seals' behaviour at low (64–70 dB) versus high (75–85 dB) sound levels, with seals orientating themselves towards or physically moving away from the louder boat noise at three different sound levels. Furthermore, seals responded more aggressively with one another and were more alert when they heard louder boat noise. Australian fur seals demonstrated plasticity in their vocal responses to boat noise with calls being significantly different between the various sound intensities and barks tending to get faster as the boat noise got louder. These results suggest that Australian fur seals on Kanowna Island show behavioural disturbance to high level boat noise. Consequently, it is recommended that an appropriate level of received boat sound emissions at breeding fur seal colonies be below 74 dB and that these findings be taken into account when evaluating appropriate approach distances and speed limits for boats.

Under likely climate change scenarios, changes to fisheries assessment, monitoring, management and governance, intended to reduce negative impacts and seize opportunities to improve performance, will form an important part of climate change adaptation responses for fisheries. Comprehensively and consistently assessing possible management adaptation options requires a clear definition of a multi-criteria evaluation framework incorporating information about the relative importance of often competing criteria or objectives. Such a framework is often missing from climate change adaptation evaluation, with adaptation priorities and plans often developed without direct reference to the key objectives of management. We used the Analytic Hierarchy Process (AHP) to develop a weighted hierarchy of objectives in four south-eastern Australian fisheries. The developed hierarchy included fisheries management objectives routinely articulated in policy and management documents, those that may underpin effective adaptation and adaptation planning, and objectives likely to contribute to ongoing adaptive capacity and resilience of fisheries and associated communities. Results of an interactive survey of managers, researchers and commercial and recreational fishers yielded average weightings of objectives that were quite consistent across the four fisheries, with a very strong preference for ensuring that adaptations support environmental and ecological values, particularly through sustaining the harvested population. However, differences between stakeholder groups were more marked, with economic objectives considered more important by commercial fishers, and social objectives by recreational fishers, than by other groups. This suggests the possibility of conflicts between groups when determining appropriate adaptation strategies, as alternative strategies will have different economic and social outcomes even if achieving comparable environmental outcomes.

Mixing models are used to determine diets where the number of prey items are greater than one, however, the limitation of the linear mixing method is the lack of a unique solution when the number of potential sources is greater than the number (n) of isotopic signatures +1. Using the IsoSource program all possible combinations of each source contribution (0-100%) in preselected small increments can be examined and a range of values produced for each sample analysed. We propose the use of a Moore Penrose (M-P) pseudoinverse, which involves the inverse of a 2x2 matrix. This is easily generalized to the case of a single isotope with (p) prey sources and produces a specific solution. The Antarctic leopard seal (Hydrurga leptonyx) was used as a model species to test this method. This seal is an opportunistic predator, which preys on a wide range of species including seals, penguins, fish and krill. The M-P method was used to determine the contribution to diet from each of the four prey types based on blood and fur samples collected over three consecutive austral summers. The advantage of the M-P method was the production of a vector of fractions f for each predator isotopic value, allowing us to identify the relative variation in dietary proportions. Comparison of the calculated fractions from this method with 'means' from IsoSource allowed confidence in the new approach for the case of a single isotope, N.

Kurylo, van Nest, and Knepper (1997 Journal of Comparative Psychology 111 126-134) have recently shown that hooded rats are able to judge the global orientation of an array of elements if orientation is signalled by the perceptual-grouping principle of proximity, but not if it is signalled by element alignment. Using a procedure designed to overcome some potential problems with the experiment of Kurylo et al, we found the same distinction in the perceptual processing of Australian sea lions. The sea lions were able to judge the orientation of arrays containing strong proximity and similarity information, but performed at chance levels judging arrays in which element alignment signalled global orientation. Human subjects were able to judge all three pattern types quickly and accurately. This is strong evidence of a qualitative distinction in the way in which perceptual grouping operates in humans and the non-human species tested. Whether this distinction is a consequence of evolutionary or experiential factors is a question for future research, but the mere fact of a qualitative difference holds important implications for our understanding of perceptual grouping.

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