scholarly journals Temporal and spatial variation in predation on juvenile herring (Clupea harengus L.) by Northeast Arctic cod (Gadus morhua L.) in the Barents Sea in 1984–1997

2002 ◽  
Vol 59 (2) ◽  
pp. 270-292 ◽  
Author(s):  
G Johansen
Keyword(s):  
Spatial Variation ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Clupea Harengus ◽  
Temporal And Spatial Variation ◽  
Arctic Cod ◽  
The Barents Sea ◽  
Temporal And Spatial

scholarly journals Marine mammals' influence on ecosystem processes affecting fisheries in the Barents Sea is trivial

2009 ◽  
Vol 5 (2) ◽  
pp. 204-206 ◽  
Author(s):  
Peter J Corkeron
Keyword(s):  
Marine Mammal ◽  
Marine Mammals ◽  
Gadus Morhua ◽  
Fishery Management ◽  
Barents Sea ◽  
Scientific Evidence ◽  
Primary Component ◽  
Clupea Harengus ◽  
Balaenoptera Acutorostrata ◽  
The Barents Sea

Some interpretations of ecosystem-based fishery management include culling marine mammals as an integral component. The current Norwegian policy on marine mammal management is one example. Scientific support for this policy includes the Scenario Barents Sea (SBS) models. These modelled interactions between cod, Gadus morhua , herring, Clupea harengus , capelin, Mallotus villosus and northern minke whales, Balaenoptera acutorostrata . Adding harp seals Phoca groenlandica into this top-down modelling approach resulted in unrealistic model outputs. Another set of models of the Barents Sea fish–fisheries system focused on interactions within and between the three fish populations, fisheries and climate. These model key processes of the system successfully. Continuing calls to support the SBS models despite their failure suggest a belief that marine mammal predation must be a problem for fisheries. The best available scientific evidence provides no justification for marine mammal culls as a primary component of an ecosystem-based approach to managing the fisheries of the Barents Sea.

scholarly journals Consumption of juvenile herring (Clupea harengus) by cod (Gadus morhua) in the Barents Sea: a new approach to estimating consumption in piscivorous fish

2004 ◽  
Vol 61 (3) ◽  
pp. 343-359 ◽  
Author(s):  
Geir Odd Johansen ◽  
Bjarte Bogstad ◽  
Sigbjørn Mehl ◽  
Øyvind Ulltang
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Age Groups ◽  
Predation Rate ◽  
Clupea Harengus ◽  
Time Range ◽  
Digestion Time ◽  
New Approach ◽  
Piscivorous Fish ◽  
The Barents Sea

Consumption of different age groups of juvenile, Norwegian, spring-spawning herring (Clupea harengus) by northeast Arctic cod (Gadus morhua) in the Barents Sea in 1992–1997 is estimated using cod stomach content data. We present a new approach to the problem of estimating consumption by fish. The new method is based on the estimation of digestion time for single prey items based on the difference between fresh weight at ingestion and weight in the stomach at time of sampling. Estimation is based on a gastric evacuation model for cod and area-specific sea temperatures. This is used to estimate the time (tmax) it takes for a prey to become digested to a stage where length is no longer measurable. Predation rate is then estimated for all prey with digestion time ≤tmax as number of prey eaten in the time range defined by tmax. This rate is combined with estimates of the proportion of the cod stock consuming the prey and area-specific abundance of cod, giving consumption of herring on a seasonal and yearly basis. The consumption estimates differ from those obtained using current methods. Predation mortality of herring is estimated directly from the consumption estimates by combining them with acoustic herring abundance data.

A baseline study of levels of mercury, arsenic, cadmium and lead in Northeast Arctic cod (Gadus morhua) from different parts of the Barents Sea

2013 ◽  
Vol 67 (1-2) ◽  
pp. 187-195 ◽  
Author(s):  
Kaare Julshamn ◽  
Arne Duinker ◽  
Bente M. Nilsen ◽  
Sylvia Frantzen ◽  
Amund Maage ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Arctic Cod ◽  
Baseline Study ◽  
The Barents Sea ◽  
Cadmium And Lead ◽  
Different Parts

scholarly journals Trophic interactions affecting a key ecosystem component: a multistage analysis of the recruitment of the Barents Sea capelin (Mallotus villosus)

2010 ◽  
Vol 67 (9) ◽  
pp. 1363-1375 ◽  
Author(s):  
Dag Øystein Hjermann ◽  
Bjarte Bogstad ◽  
Gjert Endre Dingsør ◽  
Harald Gjøsæter ◽  
Geir Ottersen ◽  
...  
Keyword(s):  
Trophic Interactions ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Clupea Harengus ◽  
Mallotus Villosus ◽  
The Barents Sea ◽  
Key Species ◽  
Capelin Mallotus Villosus ◽  
Ecosystem Component ◽  
Recruitment Stages

The Barents Sea stock of capelin ( Mallotus villosus ) has suffered three major collapses (>90% reduction) since 1985 due to recruitment failures. As capelin is a key species in the area, these population collapses have had major ecosystem consequences. By analysing data on spawner biomass and three recruitment stages (larvae, 0-group, and 1-year-olds), we suggest that much of the recruitment failures are caused by predation from herring ( Clupea harengus ) and 0-group and adult Northeast Arctic cod ( Gadus morhua ). Recruitment is furthermore positively correlated with sea temperatures in winter and spring. Harvesting of maturing capelin on their way to the spawning grounds reduced the abundance of larvae significantly, but this reduction to a large extent is compensated for later in life, as mortality is strongly density-dependent between the larval stage and age 1. Altogether, our study indicates a very high importance of trophic interactions, consistent with similar findings in other high-latitude marine ecosystems.

Temporal and spatial variation in the growth rates of Baltic herring (Clupea harengus membras L.) larvae during summer

2003 ◽  
Vol 142 (1) ◽  
pp. 25-33 ◽  
Author(s):  
T. Hakala ◽  
M. Viitasalo ◽  
H. Rita ◽  
E. Aro ◽  
J. Flinkman ◽  
...  
Keyword(s):  
Spatial Variation ◽  
Growth Rates ◽  
Clupea Harengus ◽  
Temporal And Spatial Variation ◽  
Baltic Herring ◽  
Temporal And Spatial
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