Scomber

Abstract: Summary Weight–length (W–L) relationships were estimated for 46 species of fish captured off the western Portuguese coast between April 1994 and September 1995. The best-represented family was Scyliorhinidae (2677 fishes), followed by Gadidae (1871), Sparidae (1682) and Merlucciidae (1108). The estimates for the parameter b of the W–L relationship (W = aLb) ranged between 2.171 and 3.873, with a median of 3.124. Significant variations in b were found at seasonal level for striped red mullet (Mullus surmuletus), axillary seabream (Pagellus acarne), greater weever (Trachinus draco) and the sardine (Sardina pilchardus), at the regional level for Atlantic mackerel (Scomber scombrus), and between sexes for the small-spotted dogfish (Scyliorhinus canicula).

Abstract: Population genetic structures of the mackerel (Scomber scombrus ) and chub mackerel ( Scomber japonicus ) were studied in the Mediterranean Sea. Fragments of 272 bp ( S. scomber ) and 387 bp ( S. japonicus ) of the 5′′′ ′ -end of the mitochondrial control region were sequenced from spawning individuals collected off the coasts of Greece, Italy, Spain, and Portugal. High levels of mitochondrial control region haplotypic diversity (> 0.98) were found for both Scomber species. Nucleotide diversity was higher in the mackerel (0.022) than in the chub mackerel (0.017). Global F ST values were also higher and significant in the mackerel (0.024, P 0.05). Molecular variance analyses showed differential genetic structuring for these two closely related species. There is extensive gene flow between Mediterranean Sea and Atlantic Ocean populations of chub mackerel, which are organized into a larger panmictic unit. In contrast, Mediterranean Sea populations of mackerel show some degree of genetic differentiation and are structured along an east–west axis. The analysed eastern Mediterranean Sea mackerel populations (Greece, Italy) are clearly separated from that of the western Mediterranean Sea (Barcelona), which forms a panmictic unit with eastern Atlantic Ocean populations. The genetic structures of both species showed asymmetric migration patterns and indicated population expansion.

Abstract: Publisher Summary This chapter elaborates the systematics of tunas and mackerels (Scombridae). The Scombridae is a family of 1.5 genera and about 50 species of epipelagic marine fishes. They possess many morphological and physiological adaptations that are of great interest to physiologists and evolutionary biologists. Mackerels, Spanish mackerels, bonitos, and tunas form the basis of important commercial and recreational fisheries throughout the tropical and temperate waters of the world. The subfamily Scombrinae is composed of two groups of two tribes. The more primitive mackerels (Scombrini) and Spanish mackerels (Scomberomorini) have a distinct notch in the hypural plate, lack any bony support for the median fleshy caudal peduncle keels, and do not have the penultimate vertebral centra greatly shortened. Scomber japonicus has been considered the most widespread species in the genus, sympatric with S. scombrus in the North Atlantic and with S. australasicus in the northwestern Pacific. Host–parasite relationships of parasitic copepods have been utilized to provide an independent assessment of the relationships of Spanish mackerels of the S. regalis species group.

Abstract: Atlantic mackerel ( Scomber scombrus ) were recorded in Isfjorden, Svalbard (78˚15ʹ N, 15˚11ʹ E) in late September 2013. This record is the northernmost known occurrence of mackerel in the Arctic and represents a possible northward expansion (of ca. 5˚ latitude) of its distributional range. The examined specimens of mackerel were between 7 and 11 years old, with a mean size of 39 cm and a mean weight of 0.5 kg. Examination of stomach contents indicated that the mackerel were feeding mainly on juvenile herring ( Clupea harengus ). The occurrence of mackerel in the Arctic is discussed in relation to the recent increase in mackerel population size in the North Atlantic and the expansion of other North Atlantic fishes into the Svalbard region during the last decade. Using a decadal record of water temperature, we conclude that the occurrence of Atlantic mackerel in Svalbard waters is a result of a continued warming of the ocean in the region and that it follows a general trend of species’ extending their distributional ranges northward into the Arctic.