Spatial and temporal variation in the diet of a high trophic level predator, the Australian fur seal ( Arctocephalus pusillus doriferus )

Hume, Fiona; Hindell, Mark A.; Pemberton, David; Gales, Rosemary

doi:10.1007/s00227-003-1219-0

Cited by 65 publications

(61 citation statements)

References 25 publications

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“…The diet of Australian fur seals at Seal Rocks was similar to those reported at other locations in recent years (Gales et al 1993, Gales & Pemberton 1994, Hume et al 2004, Page et al 2005, Littnan et al 2007). Across their range, Australian fur seals prey on 60 to 70 species of fishes and cephalopods.…”

Section: Prey Of Australian Fur Sealssupporting

confidence: 77%

“…The importance of particular prey varies geographically, but the principal species consumed remain the same, and include redbait, jack mackerel, barracouta, arrow squid, leatherjackets (Monocanthidae), gurnards (Triglidae), red cod and flathead species. Some inter-annual changes in diet have been reported previously, based on sampling over 2 or 3 yr at several sites (Hume et al 2004, Littnan et al 2007); the present study of over 9 yr of routine sampling, however, is by far the longest time series of data available for this species, and one of the longest for any pinniped species.Our sampling spanned an initial 4 yr of redbait scarcity in the seals' diet (<10% of prey in 1998 to 2001), then 4 yr of redbait prevalence in the diet (> 30% in 2002 to 2005) and a final year of redbait scarcity (in 2006). In years of redbait scarcity, they were replaced in the seal diet by increases in barracouta, leatherjackets and/or bearded cod.…”

mentioning

confidence: 57%

“…The number of lower cephalopod beaks identified was recorded to provide a minimum number of cephalopods in a sample. As recognised previously (Hume et al 2004 Analyses. Separate scat and regurgitate profiles and separate fish and cephalopod profiles were prepared and compared for overall diet characterisation (Gales et al 1993, Gales & Pemberton 1994, Fea et al 1999.…”

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confidence: 65%

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Sea temperature variations mediate annual changes in the diet of Australian fur seals in Bass Strait

Kirkwood¹,

Hume²,

Hindell³

2008

Mar. Ecol. Prog. Ser.

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Using a 9-yr data set, we investigated annual fluctuations in the diet of an apex predator, the Australian fur seal Arctocephalus pusillus doriferus. At Seal Rocks (northern Bass Strait), home to 25% of the entire species population, we assessed diet through collections (1997 to 2006) of scat and regurgitate samples. We identified prey remains of 42 fish taxa and 7 cephalopod taxa. Only crustaceans that were fish parasites or fish prey (amphipods and isopods) were found; no birds were identified in the samples. Six species represented 80% (as frequency of occurrence) of the fish prey, and the arrow squid Nototodarus gouldi represented 70% of cephalopod prey. There was significant annual variability in the diet. Principal component analysis indicated this was variability due to the presence of redbait Emmelichthys nitidus in some years, and its near absence and replacement in other years by increased proportions of barracouta Thyrsites atun, red cod Pseudophycis bachus and leatherjackets (Family Triglidae). Generalised Linear Models indicated the annual variation was related to mean sea surface temperatures in western Bass Strait where the seals foraged. Redbait proliferated in cooler years and were less abundant in warmer years. No corresponding annual correlation was evident between the prey assemblages and either annual fisheries catch-per-unit-effort or the annual mean Southern Oscillation Index. The propensity for diet regimes to persist for several years, then change suggests that oceanographic fluctuations probably influence previously unrecognised multi-year cyclic fluctuations of prey and of Bass Strait ecosystems. KEY WORDS: Arctocephalus · Fur seal diet · Sea temperature · Bass strait · Emmelicthys nitidus Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 369: [297][298][299][300][301][302][303][304][305][306][307][308][309] 2008 Arnould & Kirkwood 2008). Like other fur seals, such as the New Zealand fur seal A. forsteri (Harcourt et al. 2002), Australian fur seals are generalist predators and consume a range of benthic and pelagic prey; they exhibit some spatial and temporal variations in diet. During the 1920s and 1940s, their diet at breeding colonies in northern Bass Strait was determined by inspection of stomach contents in several shot animals, and comprised mainly barracouta (also known as snoek Thyrsites atun), cephalopods, and southern rock lobster Jasus novaehollandiae (Lewis 1930, McNally & Lynch 1954. In the 1980s and 1990s, the diet, determined from prey hard parts in scats and regurgitates at sites in southern Bass Strait and south of Tasmania, comprised mainly redbait Emmelichthys nitidus, jack mackerel Trachurus declivis, leatherjackets (Family Monocanthidae) and arrow squid Nototodarus gouldi (Gales et al. 1993, Gales & Pemberton 1994, Hume et al. 2004. Between 1997 and 2001 in northeastern Bass Strait, the same prey, plus red cod Pseudophycis bachus were the key species (Littnan 2003, Littnan et al. 2007; during 2001/2002 in ...

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Section: Prey Of Australian Fur Sealssupporting

confidence: 77%

mentioning

confidence: 57%

mentioning

confidence: 65%

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Sea temperature variations mediate annual changes in the diet of Australian fur seals in Bass Strait

Kirkwood¹,

Hume²,

Hindell³

2008

Mar. Ecol. Prog. Ser.

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“…In the present study, information on the size of common prey item size were obtained for the Australian fur seal (Gales et a1. 1993, Gales and Pemberton 1994, Hume et al 2004), California sea lion (Antonelis et al 1984, Weise 2000, and cape fur seal (Punt et al 1995;de Bruyn et a1. 2003;W.H.…”

Section: Methodsmentioning

confidence: 99%

Sea lions in drag, fur seals incognito: Insights from the otariid deviants

Arnould¹,

Costa²

2006

Sea Lions of the World

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“…B (Voss)) are eaten by not just the New Zealand wandering albatrosses (Imber 1992, present study), but also by a wide range of other predators across the Southern Ocean, including 5 other species of albatrosses and petrels, sharks, Patagonian toothfish and whales (Xavier & Cherel 2009, present study). Finally, the cosmopolitan species A. nodosa, which is distributed worldwide in temperate waters (including south of Australia), occurred in relatively high numbers in the diet of Gibson's wandering albatrosses (which forage extensively in temperate waters; Walker & Elliott 2006); in contrast, previous top-predator studies noted this species in relatively low numbers (Cockcroft et al 1993, Hume et al 2004, Baldassin et al 2010, and it has never been recorded in conventional net-sampling studies in the colder waters of the Southern Ocean (Table 2). Without studies such as the present one investigating the composition of the diet of marine predators, we would know much less about the distribution and habitat requirements of cephalo pods, despite their crucial role as keystone species within the marine environment.…”

Section: Cephalopod Fauna From the Pacific Sector Of The Southern Oceanmentioning

confidence: 95%

Cephalopod fauna of South Pacific waters: new information from breeding New Zealand wandering albatrosses

Xavier¹,

Walker²,

Elliott³

et al. 2014

Mar. Ecol. Prog. Ser.

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Cephalopods play an important ecological role in the Southern Ocean, being the main prey group of numerous top predators. However, their basic ecology and biogeography is still poorly known, particularly in the lightly sampled Pacific sector of the Southern Ocean. We collected and analysed information on cephalopods in that area, using Antipodean and Gibson's wandering albatrosses (Diomedea antipodensis antipodensis and D. antipodensis gibsoni, respectively) breeding at Antipodes Islands and Auckland Islands, respectively, in the New Zealand subantarctic islands as samplers, as they are known from tracking studies to cover huge areas of the Pacific sector of the Southern Ocean (Antipodean wandering albatrosses mostly forage east of New Zealand, whereas Gibson's wandering albatrosses forage west of New Zealand). A total of 9111 cephalopod beaks, from 41 cephalopod taxa, were identified from boluses (voluntarily regurgitated items by chicks). The families Histioteuthidae (e.g. Histioteuthis atlantica) and Onychoteuthidae (e.g. Moroteuthis robsoni) were the most important cephalopods numerically and by reconstructed mass, respectively, in both wandering albatross species. Combining this information with previously gathered data on cephalopods in the Atlantic and Indian sectors of the Southern Ocean, we provide evidence from predators of the circumpolar distribution of numerous key cephalopod species in the Southern Ocean, and provide new information on poorly known cephalopods (i.e. relevance in the diet of wandering albatrosses, sizes consumed, biodiversity in the South Pacific, assemblages according to predator breeding sites) in one of the most remote ocean areas in the planet.

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Spatial and temporal variation in the diet of a high trophic level predator, the Australian fur seal ( Arctocephalus pusillus doriferus )

Cited by 65 publications

References 25 publications

Sea temperature variations mediate annual changes in the diet of Australian fur seals in Bass Strait

Sea temperature variations mediate annual changes in the diet of Australian fur seals in Bass Strait

Sea lions in drag, fur seals incognito: Insights from the otariid deviants

Cephalopod fauna of South Pacific waters: new information from breeding New Zealand wandering albatrosses

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