scholarly journals Natural hybridization between immigrant narrow–barred Spanish mackerel Scomberomorus commerson (Lacepède, 1800) and endemic West African Spanish mackerel Scomberomorus tritor (Cuvier, 1832) in the Egyptian Mediterranean coast

2021 ◽  
pp. 219-227
Author(s):  
S. A. Bakhoum
Keyword(s):  
Function Analysis ◽  
Mediterranean Coast ◽  
West African ◽  
Natural Hybridization ◽  
Hybrid Index ◽  
Mahalanobis Distances ◽  
Mean Values ◽  
Spanish Mackerel ◽  
Scomberomorus Commerson ◽  
Abu Qir Bay

Immigrant narrow–barred Spanish mackerel, West African Spanish mackerel and specimens with an external appearance somewhere between these putative parents were collected from Abu Qir Bay, East Alexandria, Egypt. The hybrid index results and univariate and multivariate analysis indicated a natural hybridization between these two species. The discriminant function analysis successfully classified individual fish in the data to one of the three fish groups. Squared Mahalanobis distances extracted from the groups indicated the three groups were clearly distinct from each other. Moreover, distances between the hybrid and Scomberomorus tritor were longer than those of the hybrid and S. commerson. The mean values of the condition factor for the hybri were significantly higher than those of S. commerson. Natural mortality of the hybrid was significantly lower than that of the exotic parent (S. commerson), indicating that the environmental conditions in the examined region are more suitable for the hybrid type species than for the invasive parental species.

scholarly journals Studi Pendahuluan Hubungan Panjang–Berat Ikan Tenggiri (Scomberomorus commerson) dari Perairan Semarang

2016 ◽  
Vol 19 (2) ◽  
pp. 161
Author(s):  
Adi Santoso ◽  
Endang Sri Susilo
Keyword(s):  
Fish Growth ◽  
Small Fish ◽  
Allometric Growth ◽  
Spanish Mackerel ◽  
Weight Relationship ◽  
Scomberomorus Commerson ◽  
Java Sea ◽  
Relationship Study

Length-weight relationship study of narrow-barred spanish mackerel (Scomberomorus commerson) from Semarang waters was commenced in October-November 2014. The result showed that the fish growth at both the months of October and November 2014 was a negative allometric growth. There was uncertainty to answer the low value for b component during November although at this month was a peak of the fish catching at Java Sea.  Due to small fish landed, it indicated that narrow-barred Spanish mackerel of Semarang waters were not proper to be caught.  Keywords : narrow-barred Spanish mackerel, length-weight relationship, allometric growth Studi hubungan panjang-berat ikan tenggiri (Scomberomorus commerson) dari perairan Semarang sudah dilakukan selama bulan Oktober dan November 2014. Hasil penelitian menunjukkan bahwa pertumbuhan ikan tenggiri selama bulan Oktober maupun November 2014 adalah bersifat allometrik negative. Tidak diketahui dengan pasti penyebab kecilnya nilai b terutama pada bulan November, meskipun pada periode tersebut merupakan salah satu puncak musim penangkapan ikan tenggiri di Laut Jawa. Kecilnya ukuran ikan yang didaratkan, menunjukkan bahwa ukuran ikan tenggiri di perairan Semarang belum layak tangkap. Kata kunci: ikan tenggiri, hubungan panjang-berat, pertumbuhan allometrik 

scholarly journals Are there sex differences in the body size of the Eurasian red squirrel in Slovakia?

2015 ◽  
Vol 1 (1) ◽  
pp. 5-12 ◽  
Author(s):  
Alexander Čanády ◽  
Ladislav Mošanský ◽  
Peter Krišovský
Keyword(s):  
Function Analysis ◽  
Tail Length ◽  
The Body ◽  
Red Squirrel ◽  
Sexual Interaction ◽  
Mean Values ◽  
Foot Length ◽  
Significant Difference ◽  
Hind Foot ◽  
Males And Females

Abstract Sexual dimorphism of the Eurasian red squirrel on five somatic variables (head-and-body length, tail length, hind foot length, ear length and body weight) was evaluated on 55 squirrels. The overlap of values of the measured traits among sexes was high, but in all traits (with exception of the tail length) males seem to exhibit slightly higher mean values than females. However, these differences were non-significant, with the exception of a small significant difference in the tail length and tail-to-head-and-body ratio. Similarly, the results of discriminant function analysis show no differences between the sexes. Positive correlation analyses, together with PCA values, confirmed that tail length and hind foot length are traits that play a significant role in overall variability. We suggest that this relationship could explain their mutual importance in locomotion, where the feet are essential for movement in the trees. By contrast, the tail maintains balance on thin branches, or during jumps from one crown to another. Longer tails also demonstrate differential selection on males and females for a locomotor trait. Similarly, we discuss whether variations in tail length were connected to female reproductive success. Our results suggest that the non-significant results regarding SSD provide the benefit of the same size for both sexes in the protection of territory as well as inter- and intra-sexual interaction.

Age and growth of the narrow-barred Spanish Mackerel (Scomberomorus commerson Lacepede, 1880) in North-eastern Queensland waters

1992 ◽  
Vol 43 (5) ◽  
pp. 1269 ◽  
Author(s):  
GR McPherson
Keyword(s):  
Growth Parameters ◽  
Age And Growth ◽  
Differential Growth ◽  
Daily Growth ◽  
Spanish Mackerel ◽  
Growth Increments ◽  
Scomberomorus Commerson ◽  
North Eastern ◽  
Marginal Increment ◽  
Age Estimates

Whole otoliths were used to age Scomberomorus commerson in tropical Australian waters. Age estimates were validated by marginal-increment analysis of the first three otolith annuli. Confirmation of age estimates was provided by otolith daily growth increments and tag returns of known age. Differential growth in length, weight and longevity was evident between the sexes. The oldest male was 10 years old (127 cm FL, 19.0 kg). The oldest female was 14 years old (155 cm FL, 35 kg). The von Bertalanffy growth parameters L∞ and K were 127.5 cm and 0.25 for males and 155.0 cm and 0.17 for females.

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