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.

Meristic Analyses of Atlantic Mackerel, Scomber scombrus, from the North American Coastal Populations

1969 ◽  
Vol 26 (9) ◽  
pp. 2537-2540 ◽  
Author(s):  
K. T. MacKay ◽  
E. T. Garside
Keyword(s):  
Atlantic Ocean ◽  
Growth Rates ◽  
Biochemical Evidence ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Dorsal Fin ◽  
The North ◽  
Breeding Populations ◽  
Fin Rays ◽  
Genetic Continuity

Mean counts of vertebrae, of anal and soft dorsal fin rays, and of peduncular finlets were identical in samples of Atlantic mackerel, Scomber scombrus, from the northern and southern breeding populations in the northwest Atlantic Ocean. This information, together with growth rates and biochemical evidence from the literature, suggests that although the populations occupy separate spawning regions there is sufficient exchange of individuals at other seasons to maintain considerable genetic continuity.

Long-term trends in the distribution, abundance and seasonal occurrence of larvae of mackerel (Scomber scombrus L.) around the British Isles, 1948–1978

1981 ◽  
Vol 61 (2) ◽  
pp. 343-358 ◽  
Author(s):  
S. H. Coombs ◽  
C. E. Mitchell
Keyword(s):  
Surface Temperature ◽  
North Sea ◽  
Sea Surface ◽  
Seasonal Occurrence ◽  
British Isles ◽  
Scomber Scombrus ◽  
The North ◽  
The North Sea ◽  
Long Term Trends

The distribution, abundance and seasonal occurrence of larvae of mackerel (Scomber scombrus L.) are described from routine Continuous Plankton Recorder (CPR) sampling around the British Isles over the period 1948–78, and from more intensive CPR sampling in the Celtic Sea in 1977. There were two main areas of larval concentration: in the North Sea and over and adjacent to the Celtic Plateau; subsidiary aggregations were observed to the northwest of Ireland and to the west of Norway. There were some similarities between the distribution of larvae around the British Isles and that of adult Calanus spp. In the North Sea there was a southerly shift of larval distribution over the period 1948–77; over a similar period the abundance of larvae increased to reach high numbers by the late 1950s and subsequently declined after the mid-6os. To the south-west of the British Isles numbers of larvae showed a long-term decline. The long-term trends of distribution and abundance are discussed in relation to concurrent biological and environmental change. The clearest relationship was found between the numbers of mackerel larvae in the North Sea and sea-surface temperature in the North Atlantic, which suggests a common causative agent for both sets of observations; also, there was a weak relationship with both spawning stock biomass and sea-surface temperature at the spawning areas. In the North Sea the seasonal occurrence of larvae was from May to August, the majority being taken in June and July; over the period 1948–77 the seasonal time of occurrence of highest numbers of larvae has remained relatively constant. In the Celtic Sea the seasonal occurrence of larvae was spread over a longer period, from March to August, with relatively high numbers from March to June; over the period 1950–78 the time of occurrence has been variable, possibly with a tendency towards later timing in more recent years.

Effects of variable mean target strength on estimates of abundance: the case of Atlantic mackerel (Scomber scombrus)

2016 ◽  
Vol 74 (3) ◽  
pp. 822-831 ◽  
Author(s):  
Ben Scoulding ◽  
Sven Gastauer ◽  
David N. MacLennan ◽  
Sascha M. M. Fässler ◽  
Phillip Copland ◽  
...  
Keyword(s):  
Stock Assessment ◽  
Target Strength ◽  
Fish School ◽  
Acoustic Data ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
North East ◽  
The North ◽  
Frequency Split ◽  
Abundance And Distribution

Atlantic mackerel Scomber scombrus is a small pelagic, migratory fish which supports commercial fisheries. These fish school and are detectable using echosounders, yet fishery-independent estimates of their abundance in the North East Atlantic do not consider acoustic data. Accurate estimates of mean target strength (TS) are presently limiting echo-integration surveys from providing useful estimates of Atlantic mackerel abundance and distribution. This study provides TS estimates for in situ mackerel from multi-frequency split-beam echosounder measurements. TS equals −52.79 dB at 18 kHz, −59.60 dB at 38 kHz, −55.63 dB at 120 kHz, and −53.58 dB at 200 kHz, for a mean mackerel total length = 33.3 cm. These values differ from those currently assumed for this species in analyses of acoustic survey data. We investigate the sensitivity of acoustically estimated mackerel biomass around the Shetland Islands, Scotland, in 2014, to various estimates of TS. Confidence limits were obtained using geostatistics accounting for coverage and spatial autocorrelation. Stock biomasses, estimated from 38 and 200 kHz data, differed by 10.5%, and stock distributions were similar to each other and to the estimates from an independent stock assessment. Because mackerel backscatter at 38 kHz is dominated by echoes from the flesh and may have similarities to echoes from fish with swimbladders, and backscatter at 200 kHz is dominated by relatively stable echoes from the backbone, we recommend using 200 kHz data for estimates of Atlantic mackerel biomass.

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.

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 Pseudocollapse and rebuilding of North Sea mackerel (Scomber scombrus)

2013 ◽  
Vol 71 (2) ◽  
pp. 299-307 ◽  
Author(s):  
Teunis Jansen
Keyword(s):  
North Sea ◽  
Environmental Changes ◽  
Population Level ◽  
Northeastern Part ◽  
Scomber Scombrus ◽  
The North ◽  
Spawning Area ◽  
History Of ◽  
The North Sea ◽  
Local Stock

Abstract Jansen, T. 2014. Pseudocollapse and rebuilding of North Sea mackerel (Scomber scombrus). – ICES Journal of Marine Science, 71: 299–307. The largest observed change in mackerel (Scomber scombrus) abundance in the North Atlantic happened when the so-called “North Sea mackerel” collapsed due to overfishing. Despite protection, it has remained in a depleted state. Central to this interpretation was that the “North Sea mackerel” was considered to be a distinct spawning component. However, a recent study has shown that this is not likely. In the light of this study, a review of the history of mackerel spawning in the North Sea found that the traditional explanation of the collapse did not account for a range of unfavourable environmental changes: high fishing pressure was followed by decreasing temperatures that reduced the spawning migration into the North Sea. This was further supplemented by unfavourable changes in food and wind-induced turbulence. On the population level, this was, therefore, not a local stock collapse, but a southwest shift in spawning distribution combined with a reduction in that portion of the population cline with an affinity for spawning in the northeastern part of the spawning area, including the North Sea. No indication of irreversible genetic or behavioural losses caused by the events was found. The previously unexplained lack of rebuilding of spawning in the North Sea consequently seems related to two environmental factors that have remained unfavourable: (i) zooplankton concentration, and (ii) wind-induced turbulence. Furthermore, the large commercial autumn–winter fishery in the North Sea continues to land unknown quantities of mackerel that have an affinity for spawning in the northeastern part of the spawning area, including the North Sea.

Sign in / Sign up

Export Citation Format

Share Document