scholarly journals Foraging behaviour and prey size spectra of larval herring Clupea harengus

1992 ◽  
Vol 80 ◽  
pp. 149-158 ◽  
Author(s):  
P Munk
Author(s):  
João Neiva ◽  
Rui Coelho ◽  
Karim Erzini

Etmopterus spinax is one of the most abundant predators of the upper continental slope off the Algarve (southern Portugal), where it is captured in large quantities in deep-water fisheries. The feeding habits of E. spinax off the Algarve were investigated through the analysis of stomach contents of 376 individuals. Prey composition was described and maturity, sex and size related variations in the diet analysed. The overall diet of E. spinax suggested a fairly generalized benthopelagic foraging behaviour primarily tuned to pelagic macroplankton/microneckton, teleost fish and cephalopods. Sex and maturity related differences in the diet were not significant. Two main ontogenic diet shifts were observed at about 17 and 28 cm total length. Small and medium sized immature sharks had a diet dominated by eurybathic crustaceans, chiefly Meganyctiphanes norvegica and Pasiphaea sivado. Larger individuals consumed more teleosts and cephalopods, in part associated with scavenging as a new feeding strategy. With increasing shark size the diet diversified both in terms of resources exploited and prey size.


1996 ◽  
Vol 86 (6) ◽  
pp. 633-639 ◽  
Author(s):  
D. Dominic Amalraj ◽  
P. K. Das

AbstractThe foraging behaviour of frequency-dependent prey selection by larval instars of Toxorhynchites splendens (Wiedemann) was studied in the laboratory. Prey size selection (second vs fourth instars of Aedes aegypti Linnaeus or Anopheles stephensi Liston) by third and fourth instar predators was frequency-dependent. However, in the case of second instar predators, prey size selection was not frequency-dependent and the predator preferred second instar to fourth instar prey. When offered second instars of Aedes aegypti and Anopheles stephensi the preference for one species over the other was frequency-dependent in all the three predator instars. The role of frequency-dependent prey selection in the stability of prey—predator interaction at low equilibrium levels is discussed.


2012 ◽  
Vol 4 (1) ◽  
pp. 228-238 ◽  
Author(s):  
Kenneth L. Riley ◽  
Samantha M. Binion ◽  
Anthony S. Overton
Keyword(s):  

2005 ◽  
Vol 62 (3) ◽  
pp. 412-416 ◽  
Author(s):  
Daniel E. Duplisea

Abstract Predation size spectra were constructed for the northern Gulf of St Lawrence, covering prey size ranges that include pre-recruit cod. Predation by fish and harp seals was modelled with a log-normally distributed predator–prey size ratio along with a relationship between predator body size and the energy required. Fish concentrate predation on prey of weight 0.5–2 g, whereas harp seals prefer prey of 60–125 g. It is speculated that predation caused by harp seals on pre-recruits could be a major factor limiting cod recruitment in the system. The northern Gulf of St Lawrence is a cold boreal system with a large predatory seal population, and cod recruit older than elsewhere. Therefore, cod recruitment may be more strongly affected by predation in the northern Gulf of St Lawrence than in warmer systems such as the North Sea, where recruitment is strongly influenced by temperature.


2008 ◽  
Vol 274 (2) ◽  
pp. 198-204 ◽  
Author(s):  
A. Kalam ◽  
A. J. Urfi
Keyword(s):  

1996 ◽  
Vol 44 (2) ◽  
pp. 205 ◽  
Author(s):  
E Wapstra ◽  
R Swain

The feeding ecology of the spotted skink, Niveoscincus ocellatus, was examined over a 6-month period, from October to March, with additional data from one sample in midwinter. The investigation considered feeding activity, dietary composition and foraging strategy. Feeding activity,measured by stomach fullness, was unrelated to age, sex or reproductive status and showed little variation during the warmer months; in winter feeding was greatly reduced. N. ocellatus exhibits flexible foraging behaviour; a wide variety of terrestrial arthropods is taken opportunistically in accordance with a wide ranging foraging strategy. However, the consistent occurrence of cryptic and hidden prey indicates that active search foraging is also utilised. No evidence for ambush predation was found and, unlike many other small skinks, few arboreal or aerial prey are included in the diet, even though the habitat is rock scree and woodland where such prey abound. No evidence for any in a specific partitioning of diet based on kind or size of prey was obtained although a slight, but significant, correlation exists between maximum prey size and lizard size.


2003 ◽  
Vol 30 (4) ◽  
pp. 345 ◽  
Author(s):  
Simon Hodgkison ◽  
Jean-Marc Hero

Faecal analyses were used to investigate the diets of the endangered frogs Litoria nannotis, L. rheocola and Nyctimystes dayi in Tully Gorge, North Queensland. Comparisons of diet and food availability indicate that these species feed indiscriminately on a range of terrestrial and aquatic invertebrates. Changes in morphology and foraging behaviour significantly influenced diet composition and created subtle shifts in the degree of selectivity displayed in prey choice. Interspecific differences in numeric and volumetric diet composition were attributed to variations in gape size and microhabitat selection. Within the diets of L. nannotis and L. rheocola, a decline in prey selectivity observed during the dry season reflected a reduction in foraging activity. Differences in the gape size and foraging behaviour of males and females of L. nannotis were responsible for sex-specific differences in diet composition. L. nannotis also diplayed an ontogenetic shift in prey size and type. As snout–vent length increased, L. nannotis consumed fewer, but larger prey and increasingly discriminated against dipterans, dipteran larvae and hemipterans. Importantly, L. nannotis, L. rheocola and N. dayi demonstrated the capacity to compensate for fluctuations in food availability by feeding on less lucrative prey.


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