Foraging behavior of adult female and young-of-the-year Steller sea lions in Alaskan waters

Merrick, Richard L.; Loughlin, Thomas R.

doi:10.1139/z97-099

Cited by 201 publications

(223 citation statements)

References 25 publications

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“…1). Although individual sea lions may move among sites (Merrick & Loughlin 1997), we have assumed that sea lions haul out at sites closest to or within their most recent foraging area. Thus, scats deposited at sites were assumed to reflect prey consumed in the local area.…”

Section: Methodsmentioning

confidence: 99%

Spatial and temporal variation in the diet of Steller sea lions in the Kodiak Archipelago, 1999 to 2005

McKenzie¹,

Wynne²

2008

Mar. Ecol. Prog. Ser.

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Spatial and temporal variation in the diet of Steller sea lions Eumetopias jubatus was investigated using scat (fecal) samples collected from 4 regions in the Kodiak Archipelago. Over 2700 scats with identifiable prey were collected from the northern, eastern, southern and western sides of Kodiak Island from 1999 to 2005. Of 76 prey types identified using hard remains, the most important species in terms of frequency of occurrence and numerical abundance were Pacific sand lance Ammodytes hexapterus, walleye pollock Theragra chalcogramma, arrowtooth flounder Atheresthes stomias, Pacific cod Gadus macrocephalus, salmon Oncorhynchus spp., and Pacific herring Clupea pallasi. Significant differences in diet composition were found among regions, seasons, and years, suggesting that the diet of sea lions is strongly influenced by local and temporal distributions and abundances of prey. Herring dominated scat collections from the west coast and accounted for most (14 to 30%) of the differences in regional diet in spring and winter. Annual variation in diet was relatively low in winter, whereas spring and fall diets varied from year to year, with regional-specific shifts in dominant prey. Results from our study generally agree with diet studies conducted in the 1990s, but differ markedly in the relative importance of the major prey species.

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Section: Methodsmentioning

confidence: 99%

Spatial and temporal variation in the diet of Steller sea lions in the Kodiak Archipelago, 1999 to 2005

McKenzie¹,

Wynne²

2008

Mar. Ecol. Prog. Ser.

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“…In fact, 92% of dives in winter and 98% of dives in 583 summer made by adult females are <4 min (Merrick and Loughlin 1997). An 584 important question is how much of this diving pattern represents responses to 585 extrinsic factors (e.g., fish distribution, water depth) and how much is due to 586 intrinsic factors (e.g., physiological constraints).…”

Section: Physiological Constraints To Diving 565mentioning

confidence: 99%

Physiological constraints and energetic costs of diving behaviour in marine mammals: a review of studies using trained Steller sea lions diving in the open ocean

et al. 2016

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1Marine mammals are characterised as having physiological specializations that 2 maximize use of oxygen stores to prolong time spent under water. However, it has 3 been difficult to undertake controlled studies to determine the physiological 4 limitations and trade-offs that marine mammals face while diving in the wild under 5 varying environmental and nutritional conditions. For the past decade, Steller sea 6 lions (Eumetopias jubatus) trained to swim and dive in the open ocean away from 7 the physical confines of pools participated in studies that investigated the 8 interactions between diving behaviour, energetic costs, physiological constraints, 9and prey availability. Many of these studies measured the costs of diving to 10 understand how they vary with behaviour and environmental and physiological 11 conditions. Collectively, these studies show that the type of diving (dive bouts or 12 single dives), the level of underwater activity, the depth and duration of dives, and 13 the nutritional status and physical condition of the animal affect the cost of diving 14 and foraging. They show that dive depth, dive and surface duration, and the type of 15 dive result in physiological adjustments (heart rate, gas exchange) that may be 16 independent of energy expenditure. They also demonstrate that changes in prey 17 abundance and nutritional status causes sea lions to alter the balance between time 18 spent at the surface acquiring oxygen (and offloading CO2 and other metabolic by-19 products) and time spent at depth acquiring prey. These new insights into the 20 physiological basis of diving behaviour furthers understanding of the potential 21 scope for behavioural responses of marine mammals to environmental changes, the 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Diving metabolism of Steller sea lions 3 energetic consequences of these adjustments, and the consequences of approaching 23 physiological limits. 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Diving metabolism of Steller sea lions 4The need to study diving metabolism 25Marine mammals are well known for being able to remain submerged for extended 26 durations. Early studies of marine mammals (mainly phocid or "true" seals) 27 investigated the anatomical features by which they managed to do so. These include 28 adaptations for withstanding the intense pressures experienced at depth and 29 greater relative on-board oxygen stores than their terrestrial counterparts, which 30 allows them to remain active during submergence breath-holding. For example, 31 elevated oxygen storage is present in both circulating haemoglobin and the 32 myoglo...

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“…Immature animals ( ≥1 yr old spent a constant mean proportion of their time at sea throughout the year (water = 0.565, 0.37 to 0.76; Merrick & Loughlin 1997, Swain & Calkins 1997, Trites & Porter 2001. We assumed that pups <1 mo old spent all of their time on land (water = 0; Scheffer 1945), and that the mean percentage of time spent at sea increased linearly from 1 mo to 1 yr of age.…”

Section: P a E Ementioning

confidence: 99%

A bioenergetic model for estimating the food requirements of Steller sea lions Eumetopias jubatus in Alaska, USA

Winship¹,

Trites²,

Rosen³

2002

Mar. Ecol. Prog. Ser.

149

201

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A generalized bioenergetic model was used to estimate the food requirements of Steller sea lions Eumetopias jubatus in Alaska, USA. Inputs included age-and sex-specific energy requirements by date, population size and composition, and diet composition and energy content. Error in model predictions was calculated using uncertainty in parameter values and Monte Carlo simulation methods. Our model suggests that energy requirements of individuals were generally lowest in the summer breeding season (June to August) and highest in the winter (December to February) and spring (March to May) mainly due to changes in activity budgets. Predicted relative daily food requirements were highest for young animals (12 ± 3% SD and 13 ± 3% of body mass for 1 yr old males and females respectively) and decreased with age (5 ± 1% and 6 ± 1% of body mass for 14 yr old males and 22 yr old females respectively). The mean daily food requirement of pregnant females predicted by the model was only marginally greater than the predicted mean daily food requirement of non-pregnant females of the same age. However, the model suggested that the mean daily food requirement of females nursing pups was about 70% greater than females of the same age without pups. Of the 3 sets of model parameters (diet, population, and bioenergetic), uncertainty in diet and bioenergetic parameters resulted in the largest variation in model predictions. The model provides a quantitative estimate of the Steller sea lion population's food requirements and also suggests directions for future research. KEY WORDS: Bioenergetic model · Eumetopias jubatus · Food consumption · Steller sea lion · Sensitivity analysisResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 229: 291-312, 2002 third method for estimating food consumption is bioenergetic modeling.Biological systems are governed by the laws of thermodynamics and theoretically reach steady states where energy influx is equal to energy efflux (Wiegert 1968, Galluci 1973. In reality, a true steady state is never reached in nature, but in the long term any biological system must be in energy balance such that Consumption = Feces + Urine + Respiration + Productionwhere 'Consumption' is energy ingested, 'Feces' and 'Urine' are energy egested, 'Respiration' is energy used for work (degraded to heat), and 'Production' is energy deposited as tissue growth, fat storage, eggs, sperm, embryos, exuviae etc. (Klekowski & Duncan 1975). The energy consumption of marine mammals has frequently been estimated using bioenergetic models (Hinga 1979, Naumov & Chekunova 1980, AshwellErickson & Elsner 1981, Doidge & Croxall 1985, Hiby & Harwood 1985, Lavigne et al. 1985, Worthy 1987a, Härkönen & HeideJørgensen 1991, Markussen & Øritsland 1991, Ryg & Øritsland 1991, Markussen et al. 1992, Olesiuk 1993, Ugland et al. 1993, Mohn & Bowen 1996). These models range in detail from simple equations (with few parameters) representing an average individual's annual energy consumption, to detai...

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Foraging behavior of adult female and young-of-the-year Steller sea lions in Alaskan waters

Cited by 201 publications

References 25 publications

Spatial and temporal variation in the diet of Steller sea lions in the Kodiak Archipelago, 1999 to 2005

Spatial and temporal variation in the diet of Steller sea lions in the Kodiak Archipelago, 1999 to 2005

Physiological constraints and energetic costs of diving behaviour in marine mammals: a review of studies using trained Steller sea lions diving in the open ocean

A bioenergetic model for estimating the food requirements of Steller sea lions Eumetopias jubatus in Alaska, USA

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