scholarly journals Predation on herring, Clupea harengus, by minke whales, Balaenoptera acutorostrata, in the Barents Sea

2002 ◽  
Vol 59 (1) ◽  
pp. 58-70 ◽  
Author(s):  
U Lindstrøm
Keyword(s):  
Barents Sea ◽  
Clupea Harengus ◽  
Balaenoptera Acutorostrata ◽  
The Barents Sea ◽  
Minke Whales

scholarly journals Estimated food consumption of minke whales Balaenoptera acutorostrata in Northeast Atlantic waters in 1992-1995

2000 ◽  
Vol 2 ◽  
pp. 65 ◽  
Author(s):  
Lars P Folkow ◽  
Tore Haug ◽  
Kjell T Nilssen ◽  
Erling S Nordøy
Keyword(s):  
Barents Sea ◽  
Regional Distribution ◽  
Clupea Harengus ◽  
Mortality Factor ◽  
Point Estimate ◽  
Melanogrammus Aeglefinus ◽  
Balaenoptera Acutorostrata ◽  
Northeast Atlantic ◽  
Minke Whales ◽  
Prey Items

Data on energy requirements, diet composition, and stock size were combined to estimate the consumption of various prey species by minke whales (Balaenoptera acutorostrata) in Northeast Atlantic waters. In the period 1992-1995, the stock of 85,000 minke whales appeared to have consumed more than 1.8 million tonnes of prey per year in coastal waters off northern Norway, in the Barents Sea and around Spitsbergen during an assumed 6 month stay between mid-April and mid-October.Uncertainties in stock estimates suggest a 95% confidence range of 1.4 - 2.1 million tonnes. The point estimate was composed of 602,000 tonnes of krill Thysanoessa spp., 633,000 tonnes of herring Clupea harengus, 142,000 tonnes of capelin Mallotus villosus, 256,000 tonnes of cod Gadus morhua, 128,000 tonnes of haddock Melanogrammus aeglefinus and 54,500 tonnes of other fish species, including saithe Pollaehius virens and sand eel Ammodytes sp. Consumption of various prey items by minke whales may represent an important mortality factor for some of the species. For example, the estimated annual consumption of herring corresponds to about 70% of the herring fisheries in the Northeast Atlantic in 1995. Minke whale diets are subject to year-to-year variations due to changes in the resource base in different feeding areas. Thus, the regional distribution of consumption of different prey items is highly dynamic.

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 Direct and indirect effects of minke whale abundance on cod and herring fisheries: A scenario experiment for the Greater Barents Sea

2000 ◽  
Vol 2 ◽  
pp. 120 ◽  
Author(s):  
Tore Schweder ◽  
Gro S Hagen ◽  
Einar Hatlebakk
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Minke Whale ◽  
Clupea Harengus ◽  
Prey Abundance ◽  
Balaenoptera Acutorostrata ◽  
Time Step ◽  
Minke Whales ◽  
Spawning Stock ◽  
Capelin Mallotus Villosus

To study the pattern of interaction between minke whale (Balaenoptera acutorostrata) abundance and the main fisheries in the Greater Barents Sea, a simulation experiment was carried out. The population model involves 4 species interconnected in a food web: cod (Gadus morhua), capelin (Mallotus villosus), herring (Clupea harengus) and minke whales. Minke whales are preying on cod, capelin andherring; cod are preying on (young) cod, capelin and herring; herring in the Barents Sea are preying on capelin; while capelin is a bottom prey in the model. The consumption function for minke whales is non-linear in available prey abundance, and is estimated from stomach content data and prey abundance data. The model is dynamic, with a time step of one month, and there are two areas: the BarentsSea and the Norwegian Sea. Minke whale abundances are kept on fixed levels, while recruitment in fish is stochastic.Cod and herring fisheries are managed by quotas targeting fixed fishing mortalities, while capelin is managed with a view to allow the cod to have enough food and leaving a sufficient spawning stock of capelin. The model is simulated over a period of 100 years for a number of fixed levels of minke whaleabundance, and simulated catches of cod, herring and capelin are recorded.The experiment showed interactions between whale abundance and fish catches to be mainly linear. For cod catches, both the direct effect of whales consuming cod, and the indirect effect due to whales competing with cod for food and otherwise altering the ecosystem, are linear and of equal importance. The net effect on the herring fishery is of the same magnitude as the net effect on the cod fishery, witheach extra whale reducing the catches of both species by some 5 tonnes. These conclusions are conditional on the model and its parameterisation.

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.

Effects of predation from juvenile herring (Clupea harengus) on mortality rates of capelin (Mallotus villosus) larvae

2009 ◽  
Vol 66 (10) ◽  
pp. 1693-1706 ◽  
Author(s):  
Elvar H. Hallfredsson ◽  
Torstein Pedersen
Keyword(s):  
Barents Sea ◽  
Fish Larvae ◽  
Mortality Rates ◽  
Clupea Harengus ◽  
Mallotus Villosus ◽  
Rate Estimate ◽  
Predator Prey ◽  
The Barents Sea ◽  
Capelin Mallotus Villosus ◽  
Larvae Density

Predation has been suggested as a cause of substantial mortality of fish larvae to the degree that it might influence recruitment. This field-based study concludes that juvenile herring ( Clupea harengus ) as small pelagic predator can significantly affect mortality rates of the planktonic larvae of capelin ( Mallotus villosus ) in the Barents Sea. Surveys were carried out in the summers of 2001 and 2003. In 2001, juvenile herring were widely distributed and overlapped with capelin larvae over a wide area, whereas in 2003, the herring were more aggregated. The study focused on predation in the areas of predator–prey overlap. Capelin larvae were observed in the herring stomachs at 11 of 24 stations and at 8 of 16 stations where herring were caught in 2001 and 2003, respectively. At those stations, an estimated 7.3% and 9.9% of the capelin larvae were eaten by herring per day in 2001 and 2003, respectively. Statistical models revealed that density of capelin larvae and copepods and occurrence of euphausiids in the stomachs affected the number of capelin larvae per predator stomach. A simplified model with only capelin larvae density as predictor was converted to a functional response relationship using an experimentally derived digestion rate estimate for capelin larvae in herring stomachs.

scholarly journals In vitrodigestibility of different prey species of minke whales (Balaenoptera acutorostrata)

1993 ◽  
Vol 70 (2) ◽  
pp. 485-489 ◽  
Author(s):  
Erling S. Nordøy ◽  
Wenche Sørmo ◽  
Arnoldus Schytte Blix
Keyword(s):  
Gadus Morhua ◽  
Prey Species ◽  
Initial Step ◽  
Common Species ◽  
Clupea Harengus ◽  
Melanogrammus Aeglefinus ◽  
Balaenoptera Acutorostrata ◽  
Minke Whales ◽  
Digestion Technique

Information on diet composition, daily energy expenditure, energy storage and the utilization of energy in the prey are important factors when evaluating the food consumption of minke whales (Balaenoptera acutorostrata) during their summer stay in northern waters. The purpose of the present study was in this context to obtain information on the digestible energy (DE) of different prey selected by minke whales. Anin vitrothree-stage digestion technique, simulating the different compartments of the digestive system, has been developed. The initial step simulated the anaerobic microbial fermentation of substrate in the fortestomach. The next stage included the addition of pepsin (EC3.4.23.1)–HCI, simulating ventricle enzymic decomposition, and finally, in the third step, fresh extract from duodenal contents was used to simulate enzymic intestinal degradation of the remaining components of the food. The inoculum was normally obtained from animals which had recently eaten the prey to be tested. In such tests we obtained a dry matter disappearance (DMD) and a DE for herring (Clupea harengus) of 80·4 (SD 5·0)% (n18) and 92·1 (SD 3·7) % (n16) respectively, and a DMD of krill (Thysanoessasp.) of 83·4 (SD 4·9)% (n6). The DMD of krill was reduced to 73·8 (SD 7·3)% (n8) while the DE was 70·6 (SD 10·4) % (n7) when inoculum from whales which had recently eaten cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) was used. These results indicate a high digestibility of the most common species of prey in these animals, and also that the whales have little difficulty in changing from one prey species to another.

Trophic level and fatty acids in harp seals compared with common minke whales in the Barents Sea

2017 ◽  
Vol 13 (9) ◽  
pp. 919-932 ◽  
Author(s):  
Tore Haug ◽  
Stig Falk-Petersen ◽  
Michael Greenacre ◽  
Haakon Hop ◽  
Ulf Lindstrøm ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Trophic Level ◽  
Barents Sea ◽  
The Barents Sea ◽  
Minke Whales

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.

Diet of minke whales Balaenoptera acutorostrata in Scottish (UK) waters with notes on strandings of this species in Scotland 1992–2002

2004 ◽  
Vol 84 (6) ◽  
pp. 1241-1244 ◽  
Author(s):  
G.J. Pierce ◽  
M.B. Santos ◽  
R.J. Reid ◽  
I.A.P. Patterson ◽  
H.M. Ross
Keyword(s):  
North Sea ◽  
Stomach Contents ◽  
Clupea Harengus ◽  
Balaenoptera Acutorostrata ◽  
Sprattus Sprattus ◽  
The North ◽  
Minke Whales ◽  
The North Sea

During 1992–2002 approximately 110 strandings of minke whales Balaenoptera acutorostrata were recorded in Scotland (UK). Most strandings were recorded between April and November, with a peak of strandings of males in July and August. There were two length modes at 4–6 m and 7–10 m. Stomach contents samples were obtained from ten animals. The diet comprised mainly sandeels (Ammodytidae, around two-thirds of the diet by number or weight) and clupeids (herring Clupea harengus and sprat Sprattus sprattus). Results on diet are consistent with results from whaling catches in the North Sea. The possibility that minke whales compete with fisheries is discussed.

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