scholarly journals Modeling profitability for the smallest marine endotherms: auklets foraging within pelagic prey patches

2010 ◽  
Vol 8 ◽  
pp. 203-219 ◽  
Author(s):  
JR Lovvorn
Keyword(s):  
2016 ◽  
Vol 3 (5) ◽  
pp. 160043 ◽  
Author(s):  
Ari S. Friedlaender ◽  
David W. Johnston ◽  
Reny B. Tyson ◽  
Amanda Kaltenberg ◽  
Jeremy A. Goldbogen ◽  
...  

Air-breathing marine animals face a complex set of physical challenges associated with diving that affect the decisions of how to optimize feeding. Baleen whales (Mysticeti) have evolved bulk-filter feeding mechanisms to efficiently feed on dense prey patches. Baleen whales are central place foragers where oxygen at the surface represents the central place and depth acts as the distance to prey. Although hypothesized that baleen whales will target the densest prey patches anywhere in the water column, how depth and density interact to influence foraging behaviour is poorly understood. We used multi-sensor archival tags and active acoustics to quantify Antarctic humpback whale foraging behaviour relative to prey. Our analyses reveal multi-stage foraging decisions driven by both krill depth and density. During daylight hours when whales did not feed, krill were found in deep high-density patches. As krill migrated vertically into larger and less dense patches near the surface, whales began to forage. During foraging bouts, we found that feeding rates (number of feeding lunges per hour) were greatest when prey was shallowest, and feeding rates decreased with increasing dive depth. This strategy is consistent with previous models of how air-breathing diving animals optimize foraging efficiency. Thus, humpback whales forage mainly when prey is more broadly distributed and shallower, presumably to minimize diving and searching costs and to increase feeding rates overall and thus foraging efficiency. Using direct measurements of feeding behaviour from animal-borne tags and prey availability from echosounders, our study demonstrates a multi-stage foraging process in a central place forager that we suggest acts to optimize overall efficiency by maximizing net energy gain over time. These data reveal a previously unrecognized level of complexity in predator–prey interactions and underscores the need to simultaneously measure prey distribution in marine central place forager studies.


2003 ◽  
Vol 93 (4) ◽  
pp. 343-350 ◽  
Author(s):  
M.C. Stavrinides ◽  
D.J. Skirvin

AbstractThe effect of plant architecture, in terms of leaf hairiness, and prey spatial arrangement, on predation rate of eggs of the spider mite, Tetranychus urticae Koch, by the predatory mite Phytoseiulus persimilis Athias-Henriot was examined on cut stems of chrysanthemums. Three levels of leaf hairiness (trichome density) were obtained using two different chrysanthemum cultivars and two ages within one of the cultivars. The number of prey consumed by P. persimilis was inversely related to trichome density. At low prey densities (less than ten eggs per stem), prey consumption did not differ in a biologically meaningful way between treatments. The effect of prey spatial arrangement on the predation rate of P. persimilis was also examined. Predation rates were higher in prey patches on leaves adjacent to the release point of P. persimilis, but significantly greater numbers of prey were consumed in higher density prey patches compared to low density patches. The predators exhibited non-random searching behaviour, spending more time on leaves closest to the release point. The implications of these findings for biological control and predator–prey dynamics are discussed.


Oikos ◽  
2004 ◽  
Vol 107 (2) ◽  
pp. 265-272 ◽  
Author(s):  
Frank Van de Meutter ◽  
Robby Stoks ◽  
Luc De Meester

2007 ◽  
Vol 64 (12) ◽  
pp. 1747-1760 ◽  
Author(s):  
Espen Strand ◽  
Geir Huse

We investigate the trade-offs associated with vertical migration and swimming speed of Atlantic cod (Gadus morhua) using an adaptive individual-based model. Simulations with varying distribution and occurrence of prey, with and without swimbladder constraints, and visual predation were performed. Most simulations resulted in cod migrations between the bottom and pelagic zones. In simulations with high probability of encountering pelagic prey, the cod spent the daytime in the pelagic zone, moving to the bottom to feed only when no pelagic prey were encountered. At night the cod stayed in the pelagic zone to attain neutral buoyancy. In simulations with low occurrence of pelagic prey or high visual predation pressure, the cod remained at the bottom feeding on the consistently present benthic prey. If the pelagic prey occurred far above the sea floor or there were no benthic prey, the cod abandoned all bottom contact. The study thus predicts that the probability of encountering energy-rich pelagic prey is the key factor in driving vertical migration in adult cod. Buoyancy regulation is further shown to be an important constraint on vertical migration.


2005 ◽  
Vol 31 (4) ◽  
pp. 426-438 ◽  
Author(s):  
Doran M. Mason ◽  
Timothy B. Johnson ◽  
Chris J. Harvey ◽  
James F. Kitchell ◽  
Stephen T. Schram ◽  
...  

Author(s):  
Peter S. Rand ◽  
Brian F. Lantry ◽  
Robert O'Gorman ◽  
Randall W. Owens ◽  
Donald J. Stewart

<em>Abstract</em>.—Giant grenadier <em>Albatrossia pectoralis</em>, popeye grenadier <em>Coryphaenoides cinereus </em>and Pacific grenadier <em>C. acrolepis </em>are commercially important in the Russian Far East and dominate on continental slopes at depths above 400–600 m. Giant grenadier have become the target of a Russian bottom trawl fishery during recent years. Juveniles of grenadiers inhabit midwater layers until maturation. Commercial aggregations of adults occur near and over the bottom at depths from 300–600 m to 1,500–2,000 m. There are no considerable inter-annual changes in patterns of spatial distribution. Seasonal migrations of grenadiers are poorly understood. It was believed that they do not perform lengthy migrations, but giant grenadier has been shown to migrate along the Kuril Islands. This species is the most abundant grenadier in the study area. Ripe individuals occur all year but main spawning happens during summer and autumn. Diets of the three grenadiers differ significantly. Giant grenadier consumes benthic and interzonal organisms, Pacific grenadier eats mostly benthic invertebrates, while popeye grenadier prefers pelagic prey. Difficulties faced by the fishery include the depth of fish and poor flesh quality, which means stocks have not been heavily exploited. Processing of grenadiers for human consumption, including flesh, canned eggs, and liver, could make their harvesting more profitable.


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