scholarly journals Variable natural mortality rate of juvenile Norwegian spring-spawning herring (L.) in the Barents Sea

1998 ◽  
Vol 55 (3) ◽  
pp. 430-442 ◽  
Author(s):  
P DEBARROS ◽  
R TORESEN
Keyword(s):  
Mortality Rate ◽  
Barents Sea ◽  
Natural Mortality ◽  
The Barents Sea

Effects of predation from pelagic 0-group cod (Gadus morhua) on mortality rates of capelin (Mallotus villosus) larvae in the Barents Sea

2007 ◽  
Vol 64 (12) ◽  
pp. 1710-1722 ◽  
Author(s):  
Elvar H Hallfredsson ◽  
Torstein Pedersen
Keyword(s):  
Mortality Rate ◽  
Stomach Content ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Stomach Contents ◽  
Mortality Rates ◽  
Mallotus Villosus ◽  
The Barents Sea ◽  
Predation Mortality ◽  
Capelin Mallotus Villosus

Surveys were carried out in 2002 and 2003 to test whether predation from pelagic 0-group cod (Gadus morhua) juveniles affects mortality rates of Barents Sea capelin (Mallotus villosus) larvae. In 2002, capelin larvae were observed in 17% of the cod stomachs and predation was observed at 19 of 50 stations. In 2003, capelin larvae were observed in 8% of the cod stomachs and predation was observed at 19 of 37 stations. The stomach contents and zooplankton samples were dominated by copepods and krill. The number of capelin larvae in cod stomachs increased with increasing capelin larvae abundance and cod length and decreased with increasing stomach content of copepods and prey abundance of krill. The time when capelin larvae could be recognised after ingestion in the cod stomachs was estimated experimentally and depended on predator and prey lengths. The estimated overall predation mortality rate from juvenile cod on capelin larvae was about 1.5% per day for both years and can potentially have a significant effect on the survival of capelin larvae, depending on the overlap in the different years.

scholarly journals Integrating spatial and temporal mortality from herring on capelin larvae: a study in the Barents Sea

2009 ◽  
Vol 66 (10) ◽  
pp. 2183-2194 ◽  
Author(s):  
O. P. Pedersen ◽  
T. Pedersen ◽  
K. S. Tande ◽  
D. Slagstad
Keyword(s):  
Experimental Data ◽  
Mortality Rate ◽  
Barents Sea ◽  
Field Surveys ◽  
Fish Stocks ◽  
The Barents Sea ◽  
Spatio Temporal ◽  
The Impact ◽  
Important Fish ◽  
Temporal Overlap

Abstract Pedersen, O. P., Pedersen, T., Tande, K. S., and Slagstad, D. 2009. Integrating spatial and temporal mortality from herring on capelin larvae: a study in the Barents Sea. – ICES Journal of Marine Science, 66: 2183–2194. Barents Sea herring and capelin are commercially very important fish stocks. We investigate the spatial and temporal mortality rate of capelin larvae in 2001 as a function of herring predation. Our methods are based on Lagrangian modelling, field surveys, and experimental data. The impact of juvenile herring predation on capelin recruitment is corroborated, in particular the importance of the integrated spatio-temporal overlap between the two stocks. Capelin larvae were reduced to 20–50% in two weeks in accordance with different simulation scenarios. Hamre advanced a hypothesis in 1994 that juvenile herring are important predators of capelin larvae and a main cause of poor capelin recruitment in years when herring are very abundant in the Barents Sea. This hypothesis is supported through the results of this work.

An ecosystem element added to the assessment of Norwegian spring-spawning herring: implementing predation by minke whales

2005 ◽  
Vol 62 (2) ◽  
pp. 285-294 ◽  
Author(s):  
Sigurd Tjelmeland ◽  
Ulf Lindstrøm
Keyword(s):  
Working Group ◽  
Barents Sea ◽  
Assessment Model ◽  
Natural Mortality ◽  
Bioenergetic Model ◽  
The Barents Sea ◽  
Minke Whales ◽  
Predation Mortality ◽  
Annual Consumption ◽  
Size Estimates

Abstract Predation by minke whales is incorporated in the assessment model of the Norwegian spring-spawning herring stock (SeaStar) used by the ICES Working Group. Three assessment scenarios are performed and evaluated: (1) Default historic assessment where the natural mortality (M) is fixed, (2) assessment where natural mortality is estimated both for adult and juvenile herring, (3) assessment where consumption by minke whales is modelled and the predation and residual natural mortalities are estimated. The annual consumption of juvenile herring in the Barents Sea is estimated exogenously using diet data and a bioenergetic model. The estimated consumption is included in the objective function and the parameters determining the modelled consumption are estimated together with other free parameters of the model in a single operation. The estimated total natural mortality of juvenile herring is lower than the value assumed by the working group (M = 0.9) when either minke whales are included in the model (M = 0.49) or the parameter is estimated directly (M = 0.48). Assessment 3 generates 19% and 34% lower adult and juvenile stock sizes, respectively, than assessment 1, whereas assessments 2 and 3 generate relatively similar stock size estimates. The predation mortality constituted 45% and 10% of the total natural mortality of adult (M = 0.15) and juvenile herring (M = 0.49), respectively.

scholarly journals Who eats whom in the Barents Sea?

2000 ◽  
Vol 2 ◽  
pp. 98 ◽  
Author(s):  
Bjarte Bogstad ◽  
Tore Haug ◽  
Sigbjørn Mehl
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Natural Mortality ◽  
Balaenoptera Acutorostrata ◽  
Fish Prey ◽  
Fish Stocks ◽  
Phoca Groenlandica ◽  
The Barents Sea ◽  
Minke Whales ◽  
Important Predator

An overview of the estimates of consumption by predators on the main fish stocks in the Barents Sea is given. The main predators are cod (Gadus morhua), harp seal (Phoca groenlandica) and minke whale (Balaenoptera acutorostrata). The results indicate that cod is the most important predator, consuming about as much food annually as harp seals and minke whales combined. The consumption estimates, together with data on the amount of fish removed by commercial fisheries, are compared to estimates of the abundance and removal through natural mortality of the various species of fish prey. The consistency between these estimates is discussed. The natural mortality values for cod and haddock used in assessments are found to be reasonably consistent with the consumption estimates. The consumption of capelin is found to be higher than what is available for predation in years of low capelin abundance, while in years of high herring abundance the consumption of herring does not explain all the mortality. The way in which the consumption estimates are and can be utilised in theassessment and management of fish stocks in the Barents Sea using multispecies models and approaches is described.

Method application of optimal multi-parameter analysis to assess the distribution of water masses as an example of CTD data of the Barents Sea in summer 2017

2019 ◽  
pp. 38-51
Author(s):  
Valeriy G. Yakubenko ◽  
Anna L. Chultsova
Keyword(s):  
Barents Sea ◽  
Field Measurements ◽  
Structural Similarity ◽  
Water Masses ◽  
Parameter Analysis ◽  
Water Dynamics ◽  
Phosphorus Concentration ◽  
Nitrogen And Phosphorus ◽  
The Barents Sea ◽  
Expert Assessments

Identification of water masses in areas with complex water dynamics is a complex task, which is usually solved by the method of expert assessments. In this paper, it is proposed to use a formal procedure based on the application of the method of optimal multiparametric analysis (OMP analysis). The data of field measurements obtained in the 68th cruise of the R/V “Academician Mstislav Keldysh” in the summer of 2017 in the Barents Sea on the distribution of temperature, salinity, oxygen, silicates, nitrogen, and phosphorus concentration are used as a data for research. A comparison of the results with data on the distribution of water masses in literature based on expert assessments (Oziel et al., 2017), allows us to conclude about their close structural similarity. Some differences are related to spatial and temporal shifts of measurements. This indicates the feasibility of using the OMP analysis technique in oceanological studies to obtain quantitative data on the spatial distribution of different water masses.

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