scholarly journals Changes in weight-at-length and size-at-age of mature Northeast Atlantic mackerel (Scomber scombrus) from 1984 to 2013: effects of mackerel stock size and herring (Clupea harengus) stock size

2015 ◽  
Vol 73 (4) ◽  
pp. 1255-1265 ◽  
Author(s):  
Anna H. Olafsdottir ◽  
Aril Slotte ◽  
Jan Arge Jacobsen ◽  
Guðmundur J. Oskarsson ◽  
Kjell R. Utne ◽  
...  
Keyword(s):  
Prey Availability ◽  
Somatic Growth ◽  
Recent Decade ◽  
Clupea Harengus ◽  
Negative Effects ◽  
Norwegian Sea ◽  
Stock Size ◽  
Northeast Atlantic ◽  
Atlantic Mackerel ◽  
Scomber Scombrus

Abstract Weight-at-length and length-/weight-at-age were analysed for mature 3- to 8-year-old Northeast Atlantic mackerel (Scomber scombrus; n= 26 084) collected annually in autumn (September and October) at the end of the annual feeding season during 1984–2013 in the northern North Sea. The age range represented 92% of the mackerel stock size (age 3+). During the most recent decade, mackerel length- and weight-at-age continually declined. In 2013, the average mackerel was 3.7 cm shorter and weighed 175 g less than the average individual in 2002. Individual weight-at-length, demonstrating annual summer feeding success, continually declined during the most recent 5 years, whereas somatic growth of cohorts aged 3–8 continually declined for the last 11 of 25 cohorts investigated. Growth of the latest cohort was 34% of the maximum cohort growth recorded. Both weight-at-length and cohort growth were negatively affected by mackerel stock size and Norwegian spring-spawning herring (Clupea harengus) stock size (weight-at-length: r2 = 0.89; growth (length): r2 = 0.68; growth (weight): r2 = 0.78), while temperature was not significant. Conspecific density-dependence was most likely mediated via intensified competition associated with greater mackerel density. Negative effects of herring were likely mediated by exploitative competition for shared food resources rather than direct competition due to limited spatio-temporal overlap between mackerel and herring during the feeding season. Herring begin their seasonal feeding migration at least a month before mackerel; therefore, herring consumption influences prey availability for the later-arriving mackerel. Record low mackerel growth and negative effects of mackerel and herring stock size suggest that the carrying capacity of the Norwegian Sea and adjacent areas for plankton-feeding fish stocks have been reached. However, compounding effects of a less productive Norwegian Sea during the 30-year period cannot be excluded.

scholarly journals Sharing the Northeast Atlantic mackerel

2012 ◽  
Vol 70 (2) ◽  
pp. 259-269 ◽  
Author(s):  
Rögnvaldur Hannesson
Keyword(s):  
Time Horizon ◽  
The Other ◽  
Faroe Islands ◽  
Fishing Mortality ◽  
The European Union ◽  
Cooperative Solution ◽  
Northeast Atlantic ◽  
Density Dependent ◽  
Atlantic Mackerel ◽  
Scomber Scombrus

Abstract The sharing of the Northeast Atlantic mackerel (Scomber scombrus) stock is analysed as a game between four parties: the European Union, Norway, the Faroe Islands, and Iceland. Consideration is given to how the outcome depends on the nature of the stock's migrations. Two types of migrations are considered: (i) density-dependent, where the mackerel migrates into the Icelandic economic zone only if it exceeds 3.5 million t, and (ii) stochastic migrations, where the said migrations are stochastic. It is determined that the Faroe Islands would never accept a cooperative solution wherein they can only fish with the globally optimal fishing mortality within their own zone. This is also true for Iceland when the migrations into her zone are stochastic, but not if they are density-dependent. In the latter case, the other players have incentives to retaliate to Icelandic overfishing by fishing harder, which greatly reduces the number of years when mackerel are available in the Icelandic zone. It is assumed that the objective is maximization of the catch volume over a time-horizon of 50 years.

scholarly journals Development of a stock–recruit model for simulating stock dynamics for uncertain situations: the example of Northeast Atlantic mackerel (Scomber scombrus)

2011 ◽  
Vol 68 (5) ◽  
pp. 848-859 ◽  
Author(s):  
E. John Simmonds ◽  
Andrew Campbell ◽  
Dankert Skagen ◽  
Beatriz A. Roel ◽  
Ciaran Kelly
Keyword(s):  
Stock Assessment ◽  
Management Plan ◽  
Maximum Sustainable Yield ◽  
Fish Stock ◽  
Northeast Atlantic ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Functional Forms

Abstract Simmonds, E. J., Campbell, A., Skagen, D., Roel, B. A., and Kelly, C. 2011. Development of a stock–recruit model for simulating stock dynamics for uncertain situations: the example of Northeast Atlantic mackerel (Scomber scombrus). – ICES Journal of Marine Science, 68: 848–859. The assumption of a relationship between recruitment and a spawning stock is the cornerstone of the precautionary approach and may constrain the use of a maximum sustainable yield (MSY) target for fisheries management, because the failure to include such a relationship suggests that providing a measure of stock protection is unnecessary. The implications of fitting different functional forms and stochastic distributions to stock-and-recruit data are investigated. The importance of these considerations is shown by taking a practical example from management: the management plan for Northeast Atlantic mackerel (Scomber scombrus), a fish stock with an average annual catch of 600 000 t. The historical range of spawning-stock biomass is narrow, and historical data from a stock assessment explain only a small proportion of the recruitment variability. We investigate how best to reflect the uncertainty in the stock–recruit relationship. Selecting a single model based on simple statistical criteria can have major consequences for advice and is problematic. Selecting a distribution of models with derived probabilities gives a more complete perception of uncertainty in dynamics. Differences in functional form, distribution of deviations, and variability of coefficients are allowed. The approach appropriately incorporates uncertainty in the stock–recruit relationship for FMSY estimation.

Estimating natural interstage egg mortality of Atlantic mackerel (Scomber scombrus) and horse mackerel (Trachurus trachurus) in the Northeast Atlantic using a stochastic model

2007 ◽  
Vol 64 (12) ◽  
pp. 1656-1668 ◽  
Author(s):  
Enrique Portilla ◽  
Eddie McKenzie ◽  
Doug Beare ◽  
Dave Reid
Keyword(s):  
Process Model ◽  
Mortality Rates ◽  
Horse Mackerel ◽  
Fish Biomass ◽  
Trachurus Trachurus ◽  
Northeast Atlantic ◽  
Egg Mortality ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Egg Stages

Egg mortality is a key parameter for understanding early life histories of fish. Small variations in estimated mortality cause large differences on adult fish biomass estimates. Therefore, the assumption of a constant egg mortality rate may be misleading. Here, we show how to estimate mortality rates for the individual egg stages of Atlantic mackerel (Scomber scombrus) and horse mackerel (Trachurus trachurus) from triennial surveys conducted since 1977. We use a standard, continuous-time Markov process model that combines the numbers of eggs sampled in each stage with experimental data on egg stage duration (dependent on water temperature). This is the first attempt to study mortality among egg stages in such detail and the first comprehensive effort to estimate horse mackerel egg mortality in the Northeast Atlantic. The results include detailed descriptions of spatial–temporal dependencies in mortality. The daily egg mortality rates estimated are ~0.56·day–1 for Atlantic mackerel (far higher than suggested in the literature) and 0.54·day–1 for horse mackerel. Although it was not possible to estimate stage 1 egg mortality directly, the results suggest high mortality in the first stage. This might lead to underestimation of fish biomass when assessed traditionally by egg survey data alone.

Di-n-hexyl Phthalate (DHP), a Newly Identified Contaminant in Atlantic Herring (Clupea harengus harengus) and Atlantic Mackerel (Scomber scombrus)

1981 ◽  
Vol 38 (7) ◽  
pp. 856-859 ◽  
Author(s):  
Charles J. Musial ◽  
John F. Uthe ◽  
Gary R. Sirota ◽  
B. Garth Burns ◽  
Michael W. Gilgan ◽  
...  
Keyword(s):  
Acid Ester ◽  
Phthalic Acid ◽  
Clupea Harengus ◽  
Proton Nuclear Magnetic Resonance ◽  
Atlantic Herring ◽  
Isolation And Identification ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Phthalic Acid Ester ◽  
Clupea Harengus Harengus

We describe the isolation and identification of di-n-hexyl phthalate, a new marine pollutant found in Atlantic herring (Clupea harengus harengus) and Atlantic mackerel (Scomber scombrus). This compound was isolated from extracted lipids by a combination of gel permeation, high performance liquid and column chromatography, and selective precipitation of impurities. Conclusive proof of its structure was obtained from gas chromatographic–mass spectrometric analysis and proton nuclear magnetic resonance spectroscopy. The concentrations of di-n-hexyl phthalate (17–27 μg/g wet weight), which is not a major industrial phthalic acid ester, far exceeded those of dibutyl and di-2-ethylhexyl phthalates, the major industrial phthalic acid esters. Thus the possibility of selective bioaccumulation of DHP in herring and mackerel was indicated. This finding is important in view of the paucity of toxicological information concerning this compound.Key words: phthalic acid ester, di-n-hexyl phthalate (DHP), analysis, mackerel, herring, marine fish, pollution

scholarly journals Quantifying changes in abundance, biomass, and spatial distribution of Northeast Atlantic mackerel (Scomber scombrus) in the Nordic seas from 2007 to 2014

2015 ◽  
Vol 73 (2) ◽  
pp. 359-373 ◽  
Author(s):  
Leif Nøttestad ◽  
Kjell R. Utne ◽  
Guðmundur J. Óskarsson ◽  
Sigurdur Þ. Jónsson ◽  
Jan Arge Jacobsen ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Nordic Seas ◽  
Northeast Atlantic ◽  
Atlantic Mackerel ◽  
Scomber Scombrus
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