Harvesting Strategies and Fishing Mortality Reference Point Comparisons for the Northwest Atlantic Stock of Atlantic Mackerel (Scomber scombrus)

1993 ◽  
Vol 50 (8) ◽  
pp. 1749-1756 ◽  
Author(s):  
William J. Overholtz
Keyword(s):  
Population Level ◽  
Northwest Atlantic ◽  
Harvest Rate ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Predation Mortality ◽  
Fishing Strategies ◽  
Spawning Stock ◽  
Current Minimum

Previous research indicated that density dependence in population-level responses such as growth and predation mortality rate may play a major role in regulating the dynamics of the Northwest Atlantic stock of Atlantic mackerel (Scomber scombrus). Simulation studies, utilizing this compensatory model of the mackerel stock, suggest that expected yields and spawning stock sizes under conditions of constant harvest rate or constant catch would be quite disparate. Yields and spawning stock size would be less variable and slightly larger under a constant catch strategy for catches of mackerel up to approximately 200 000 t. However, a constant harvest rate strategy would provide higher long-term yields and a more stable spawning stock at catches greater than 200 000 t. A comparison of a constant catch policy with F0.1, F20, and Fmax fishing strategies (constant F) suggests that the Fmax and F20 strategies would cause a long-term decline in the spawning stock below the current minimum spawning stock target and provide highly variable yields. A constant catch strategy could produce nearly the same level of yield with considerably less variability and maintain a larger mean spawning stock biomass than the F0.1 strategy.

scholarly journals Multi-decadal trends in contingent mixing of Atlantic mackerel (Scomber scombrus) in the Northwest Atlantic from otolith stable isotopes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kohma Arai ◽  
Martin Castonguay ◽  
David H. Secor
Keyword(s):  
Stable Isotopes ◽  
Stock Assessment ◽  
Northwest Atlantic ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Stock Biomass ◽  
Oxygen Stable Isotopes ◽  
The Us ◽  
Spawning Stock ◽  
The Status

AbstractThe Atlantic mackerel (Scomber scombrus) in the Northwest Atlantic is comprised of northern and southern components that have distinct spawning sites off Canada (northern contingent) and the US (southern contingent), and seasonally overlap in US fished regions. Thus, assessment and management of this population can be sensitive to levels of mixing between contingents, which remain unknown. Multi-decadal trends in contingent mixing levels within the US fisheries region were assessed, and the contingent composition across seasons, locations, ages, and size classes were characterized using archived otoliths and developing a classification baseline based on juvenile otolith carbon and oxygen stable isotopes (δ13C/δ18O values). Classification of age ≥ 2 adults demonstrated that northern contingent mixing was prevalent within the US continental shelf waters during the past 2 decades (2000–2019), providing an important seasonal subsidy to the US winter fishery despite substantial depletion in spawning stock biomass of the dominant northern contingent. While the majority of older fish were of the northern contingent during the early 2000s, the southern contingent contribution increased with age/size class during the recent period (2013–2019). Spatial mixing was most prevalent during February and March when the northern contingent occurred as far south as the Delmarva Peninsula, but were mostly absent from US waters in May. A positive relationship (albeit not significant; r = 0.60, p = 0.07) occurred between northern contingent mixing and US fisheries landings, which could imply that higher contingent mixing levels might be associated with greater landings for the US winter mackerel fishery. The yield of the Northwest Atlantic mackerel depends upon the status of the northern contingent, with the southern contingent possibly more prone to depletion. Spatially explicit stock assessment models are recommended to conserve both productivity and stability in this two-component population.

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.

Usefulness of Fourier Analysis of Otolith Shape for Atlantic Mackerel (Scomber scombrus) Stock Discrimination

1991 ◽  
Vol 48 (2) ◽  
pp. 296-302 ◽  
Author(s):  
Martin Castonguay ◽  
Patrick Simard ◽  
Pierre Gagnon
Keyword(s):  
Stock Structure ◽  
Discriminant Functions ◽  
Position Effects ◽  
Northwest Atlantic ◽  
Otolith Shape ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
The North ◽  
Stock Discrimination ◽  
The North Sea

We compared shapes of Atlantic mackerel (Scomber scombrus) sagittae between the two contingents (i.e. spawning groups) from the Northwest Atlantic and between the stocks from the Northwest Atlantic and the North Sea to evaluate whether otolith shape could differentiate between the two contingents in a mixed fishery. We quantified shapes with the Fourier series, an objective and rapid method which decomposes a shape's outline into a series of sinusoids. To determine a correct way to compare contingents/stocks, we first assessed four intracontingent effects on otolith shapes. Age and year-class effects were significant, while sex and bilateral position effects were not. This temporal instability in shapes indicates that confounding effects of age and year-class on otolith shapes need to be assessed carefully before drawing conclusions on stock structure. It also shows that comparative studies of otolith shapes with Fourier descriptors are not useful for mackerel contingent discrimination. The power of discriminant functions to correctly classify test mackerel samples separated by age and sampling year, on the basis of otolith shape, was better for comparisons between the stocks than for those between the contingents.

A Surplus Yield Model Incorporating Recruitment and Applied to a Stock of Atlantic Mackerel (Scomber scombrus)

1978 ◽  
Vol 35 (2) ◽  
pp. 229-234 ◽  
Author(s):  
Gilbert G. Walter
Keyword(s):  
Fisheries Management ◽  
Fishing Mortality ◽  
Yield Model ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Stock Biomass ◽  
Equilibrium Yield ◽  
Class Strength ◽  
Nonequilibrium Conditions

A modification of Schaefer's surplus yield model that takes into account variations in year-class strength is introduced. Expressions for long-term equilibrium yield under assumptions of both linear and density-dependent recruitment are derived and compared. Strategies for exploitation under nonequilibrium conditions are discussed and equations derived. The model is fitted to a stock of mackerel and projections for the stock biomass in 1980 under various levels of fishing mortality are made. Key words: mathematical model, fisheries management, stock biomass projections

Long-Distance Migration of an Atlantic Mackerel (Scomber scombrus)

1974 ◽  
Vol 31 (9) ◽  
pp. 1521-1522 ◽  
Author(s):  
L. S. Parsons ◽  
J. A. Moores
Keyword(s):  
Long Island ◽  
Long Distance ◽  
Northwest Atlantic ◽  
Atlantic Mackerel ◽  
Scomber Scombrus

The recapture south of Long Island of an Atlantic mackerel (Scomber scombrus) tagged in Newfoundland waters represents a migration of at least 2259.6 km (1400 miles), the farthest documented migration of mackerel ever reported from the Northwest Atlantic. This recapture supports earlier tagging evidence that overwinter mixing may occur between the northern and southern populations of mackerel.

scholarly journals The advantage of explicitly incorporating predation mortality into age-structured stock assessment models: an application for Atlantic mackerel

2009 ◽  
Vol 66 (3) ◽  
pp. 445-454 ◽  
Author(s):  
H. Moustahfid ◽  
J. S. Link ◽  
W. J. Overholtz ◽  
M. C. Tyrrell
Keyword(s):  
Stock Assessment ◽  
Fish Predation ◽  
Reference Points ◽  
Assessment Model ◽  
Fishing Mortality ◽  
Atlantic Mackerel ◽  
Predation Mortality ◽  
Spawning Stock ◽  
Age Structured ◽  
The Impact

AbstractMoustahfid, H., Link, J. S., Overholtz, W. J., and Tyrrell, M. C. 2009. The advantage of explicitly incorporating predation mortality into age-structured stock assessment models: an application for Atlantic mackerel. – ICES Journal of Marine Science, 66: 445–454. An age-structured assessment programme (ASAP) that explicitly incorporates predation mortality was applied to Atlantic mackerel (Scomber scombrus) in the Northwest Atlantic. Predatory removals were modelled in the same manner as fishing mortality, with a comparable set of time-series, to produce estimates of predation mortality at age and for each year. Results from the analysis showed that incorporating predation into a mackerel stock assessment model notably altered model outputs. When excluding explicitly modelled rates of predation, the model underestimated the magnitude and uncertainty in spawning-stock biomass (SSB) and recruitment. Further, the rates of predation mortality varied across time and were higher for younger fish. Predation mortality was higher than fishing mortality for fish aged 1 year, approximately equal for 2-year-olds, and lower for older fish (3 years and older). Biological reference points for Atlantic mackerel differed considerably when predation mortality was included. For example, SSBMSY was more than twice as high in the model where predation was incorporated than in the fisheries-only model. Although there are several caveats to the predation model outputs, chief of which is that the estimates are conservative because some mackerel predators were excluded, the results demonstrate the feasibility of executing such an approach with an extant tool. The approach presented here ultimately has the advantage of detecting, and upon detection parsing out, the impact of predators relative to fisheries and has the potential to provide useful information to those interested in small pelagic fish and their associated fisheries.

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