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A joint spatio–temporal distribution model of mackerel (ages 3–10) was developed to investigate the age-based responses of mackerel to three environmental drivers: sea surface temperature (SST), mixed layer depth, and chlorophyll-a concentration during the summer months 2010–20 in the Nordic Seas. The study showed that SST was the most important variable amongst the ones tested and had the strongest impact on the distribution of the younger age classes (3–5), which had a narrower range of favourable SST and a stronger aversion to cold temperatures than older individuals. Consequently, the impact of SST differed regionally; in the polar front regions, SST explained up to 61% of the variability in the observed density of young individuals, where Arctic water masses likely acted as a barrier to these young individuals. That said, part of it could be confounded with the limited migration capability of young mackerels, which could not reach the furthest frontal regions. In warmer southern waters, the same environmental variables had less explanatory power for mackerel of all ages. Individuals in the south were likely not constrained by temperature and perhaps more influenced by other variables, such as food availability or ocean current (throughout their migration path), for which appropriate data are lacking. Moreover, the model showed that older mackerel were distributed more to the north and west, and their migration pattern changed when the 2013 year-class no longer migrated to the west compared to previous year-classes. Additionally, all-year classes started migrating more eastward from summer 2018. [ABSTRACT FROM AUTHOR]

We present a genome assembly from an individual Scomber scombrus (the Atlantic mackerel; Chordata; Actinopteri; Scombriformes; Scombridae). The genome sequence has a total length of 764.10 megabases. Most of the assembly is scaffolded into 24 chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 16.56 kilobases in length.

The assessment of fish health has acknowledged the significance of helminthology and haematology characteristics as crucial instruments. The utilization of blood parameter measurement has been a longstanding practice in the field of fish health monitoring. The current study aimed to examine the impact of an indigenous infestation of parasites on various blood parameters, including activities of liver, kidney function tests, lipase, amylase, Creatine phosphokinase (CPK), and Lactate Dehydrogenase (LDH). The present study was undertaken to investigate the parasitic infection in a sample of 100 fish. The sample consisted of 50 of Euthynnus alletteratus, and 50 Scomber Scombrus. These fish were gathered from the waters of Misrata city, located in Libya. Results revealed the presence of statistically significant differences across various indices in both Euthynnus alletteratus and Scomber scombrus. A significant positive association was seen between urea values and many organs in Scomber scombrus, with the exception of the external body. Similarly, in Euthynnus alletteratus, a significant positive correlation was found between urea values and various organs, except for the external body and nostrils. The results of the study indicate that there is a positive link between creatinine levels and several internal organs in Euthynnus alletteratus, with the exception of external body tissues. A favorable correlation was seen between sodium levels and various organs in Scomber scombrus, with the exception of internal organs and the stomach. There was a positive correlation seen between potassium, Aspartate Aminotransferase (AST), Alanine Aminotransferase (ALT), Alkaline Phosphatase (ALP), lipase, amylase, CPK, and total protein levels in several organs of both Euthynnus alletteratus and Scomber scombrus. A significant correlation was observed between LDH levels and several organs in both Euthynnus alletteratus and Scomber scombrus, with the exception of the external body in Scomber scombrus. In Euthynnus alletteratus, LDH levels were favorably connected with the nose, internal organs, and anterior intestine. [ABSTRACT FROM AUTHOR]

This research aimed at assessing the heavy metals concentration in imported Scomber scombrus fish samples purchased from cold rooms in Lagos, Nigeria. The samples were digested using the wet digestion method, and the concentration of Chromium (Cr), Arsenic (As), Lead (Pb), and Cobalt (Co) were determined using Atomic Absorption Spectrophotometer. Chromium (Cr) was present in twelve Scomber scombrus samples, and the level ranged from 0.004 to 0.046 mg/kg, while arsenic (As) was present in seven fish samples, with concentrations varying within 0.001 to 0.006 mg/kg. Lead (Pb) was present in eleven samples and not detected in SS5 and SS7. The concentration ranged from 0.004 to 0.062 mg/kg. Cobalt (Co) was present in seven Scomber scombrus samples, the level ranged from 0.004 to 0.046 mg/kg. However, SS3, SS10, and SS13 had lead concentrations above the maximum permissible limit (0.05 mg/kg) recommended by WHO/FAO. This study established the need for Nigerian agencies in charge of food to verify, check and ascertain the safety of imported fish before endorsing them as harmless for citizens' consumption.

Anisakis simplex sensu stricto is a parasite infecting several commercial fish species in the Northeast (NE) Atlantic, known to be the aetiological agent of the human zoonosis anisakiasis. The present study investigated the response of A. simplex (s. s.) third stage larvae (identified to species level by mtDNA cox 2 sequencing) to the storage time and temperature of Atlantic herring (Clupea harengus), Atlantic mackerel (Scomber scombrus) and blue whiting (Micromesistius poutassou) from NE Atlantic fishing areas. A total of 300 fish per species were divided in batches of 50 individuals straight after catch. Each batch was stored at different temperature conditions (2 °C, 5 °C, 15 °C) for different time intervals (24h and 48h). A batch of 50 fish of each species was frozen immediately after catch and used as control (time zero). All fish were inspected by the UV-press method. Blue whiting was the most infected fish species while mackerel harboured the highest proportion of intra-vitam A. simplex (s. s.) larvae in the musculature. In blue withing there was a significant increase in the proportion of larvae in the muscle with increasing storage temperatures (5 °C < 15 °C) and time (24h < 48h). Herring showed a weak trend of increasing parasite infection in the muscle with increasing temperature/time. In contrast, no significant differences of muscle/viscera larval distribution were observed between batches of mackerel stored at different temperatures for different time intervals. Storage temperature and time seem to play a role in the post-mortem motility of A. simplex (s. s.) larvae in herring and blue whiting. Keeping the temperature at ≤ 2 °C seems to prevent post-mortem larval migration into the flesh during fish storage, handling, and transport. Besides abiotic variables, the differences observed in larval post-mortem motility in the different fish species are biologically determined, and attributable to species-specific host-parasite interactions. • Response of A. simplex (s. s.) larvae to storage time/temperature in three fish species. • Intra-vitam and post-mortem migration were detected. • Intra-vitam migration rate depends on parasite and fish species. • Post-mortem migration rate can be controlled with proper storage temperature. • Storing fish at <2 °C can largely prevent post-mortem larval migration. [ABSTRACT FROM AUTHOR]