Validating the relationship between 3-dimensional body acceleration and oxygen consumption in trained Steller sea lions

We compared eight dietary indices used to describe the diet of Steller sea lions (Eumetopias jubatus (Schreber, 1776)) from 2001 to 2004 in Frederick Sound, southeast Alaska. Remains (n = 9666 items) from 59+ species categories were identified from 1684 fecal samples (scats) from 14 collection periods. The most frequently occurring prey were walleye pollock (Theragra chalcogramma (Pallas, 1814) = Gadus chalcogrammus Pallas, 1814; 95%), Pacific herring (Clupea pallasii Valenciennes in Cuvier and Valenciennes, 1847; 30%), Pacific hake (Merluccius productus (Ayres, 1855); 29%), and arrowtooth flounder (Atheresthes stomias (Jordan and Gilbert, 1880) = Reinhardtius stomias (Jordan and Gilbert, 1880); 21%). These species, along with Pacific salmon (genus Oncorhynchus Suckley, 1861) and skate (genus Raja L., 1758), accounted for 80%–90% of the reconstructed biomass and energy contribution, with pollock contributing 37%–60%. Overall, 80% of fish were 14–42 cm long and mainly pelagic, though 40% of scats contained benthic-associated prey. Steller sea lions switched from adult pollock to strong cohorts of juvenile pollock, and took advantage of spawning concentrations of salmon in autumn and herring in late spring and summer, as well as a climate-driven increase in hake availability. Observed temporal and site differences in diet confirm the need for robust long-term scat sampling protocols. All major indices similarly tracked key temporal changes, despite differences in occurrence and biomass-energy-based diet estimates linked to prey size and energy-density effects and the application of correction factors.

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Active brood care in Cancer setosus (Crustacea: Decapoda): the relationship between female behaviour, embryo oxygen consumption and the cost of brooding

Functional Ecology ◽

10.1046/j.1365-2435.2002.00616.x ◽

2002 ◽

Vol 16 (2) ◽

pp. 241-251 ◽

Cited By ~ 86

Author(s):

J. A. Baeza ◽

M. Fernández

Keyword(s):

Oxygen Consumption ◽

Brood Care ◽

Female Behaviour ◽

The Cost ◽

The Relationship

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Maternal attendance patterns of Steller sea lions (Eumetopias jubatus) from stable and declining populations in Alaska

Canadian Journal of Zoology ◽

10.1139/z03-008 ◽

2003 ◽

Vol 81 (2) ◽

pp. 340-348 ◽

Cited By ~ 35

Author(s):

Linda L Milette ◽

Andrew W Trites

Keyword(s):

Prey Availability ◽

A Priori ◽

Population Decline ◽

Perinatal Period ◽

Eumetopias Jubatus ◽

Steller Sea Lions ◽

Sea Lions ◽

First Feeding ◽

Attendance Patterns ◽

The Mean

Maternal attendance patterns of Alaskan Steller sea lions (Eumetopias jubatus) were compared during the summer breeding seasons in 1994 and 1995 at Sugarloaf Island (a declining population) and Lowrie Island (a stable population). Our goal was to determine whether there were differences in maternal attendance between the two populations that were consistent with the hypothesis that lactating Steller sea lions in the area of decline were food-limited during summer. Our a priori expectations were based on well-documented behavioural responses of otariids to reduced prey availability. We found that foraging trips were significantly shorter in the area of population decline, counter to initial predictions. The mean length of foraging trips in the declining area was 19.5 h compared with 24.9 h in the stable area. In contrast, the mean perinatal period (time between parturition and first feeding trip) was significantly longer in the area of decline (9.9 versus 7.9 days), again countering initial predictions. The mean length of shore visits for the declining population was also significantly longer (27.0 h compared with 22.6 h where the population was stable). For both populations, the mean time that mothers foraged increased as pups grew older, whereas the time that they spent on shore with their pups became shorter. Behavioural observations of maternal attendance patterns are inconsistent with the hypothesis that lactating Steller sea lions from the declining population had difficulty obtaining prey during summer.

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