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Fresh small pelagic fish (Indian mackerel, spotted sardine and yellowtail scad) from the Eritrean waters of the Red Sea were investigated for their physicochemical properties (morphometric measurements, proximate composition, pH, salt, mineral content, color and oxidation indicators) and microbiological characteristics (total plate count; TPC, total coliforms; TC, E. coli, S. aureus, Salmonella spp.; V. parahaemolyticus, halophilic count and total fungal count; TFC). The morphometric measurements indicated that the yellow tail scad had the largest weight (47.6 g) and the smallest number of fish pieces (21) per kg. These small pelagic fish can be characterized as low-fat fish (3.26–3.85%) and a good protein source, with the highest protein content recorded in fresh Indian mackerel (21.29%). The ash and fiber content fell within the range of 1.57–1.77% and 0.24–0.38% respectively. The oxidation indicators (free-fatty acid, peroxide value, thiobarbituric acid, and p-anisidine value) were below the maximum allowable values in fresh fish. The fish were good sources of minerals (Ca, Mg, Fe and Zn), but the Indian mackerel exhibited the highest level of Cd content (0.04 mg/kg weight) which was still below the maximum permitted levels (0.25 mg/kg weight). The TPC, TC, E. coli, S. aureus, and halophilic count were below maximum allowable levels while Salmonella, V. parahaemolyticus and TFC were absent in the fresh fish samples.

In the Persian Gulf handline fishery, fishers mostly use Cutlassfish (Trichiurus lepturus) bait for targeting narrow-barred Spanish mackerel (Scomberomorus commerson) However, Cutlassfish are expensive compared to other baits and also a commercially important species that is typically exported to Asian countries. In order to conserve Cutlassfish resources and reduce costs of fishing, the effect of changing bait type and size on the catch efficiency and size structure of narrow-barred Spanish mackerel caught in the Persian Gulf handline fishery was investigated. The alternative baits investigated, Indian mackerel (Rastrelliger kanagurta) and artificial bait (lead lure), resulted in a lower overall catch efficiency and a shift in catch pattern towards smaller individuals. The two alternative baits had very similar overall catch efficiencies. The results obtained demonstrate that bait type and size affects both overall catch efficiency and size structure of narrow-barred Spanish mackerel caught in the Persian Gulf handline fishery. This implies that managing bait type and size might complement standard harvest regulations and facilitate changing exploitation pattern in the Persian Gulf handline fishery.

Fisheries impacts on marine megafauna have received global attention and are recognized as a serious problem. In Saudi waters of the Arabian Gulf, the artisanal fishery is responsible for 99.6% of landings. It uses a range of boat sizes and various types of fishing gears and operates in all accessible areas from shallow coastal bays to deep offshore waters. The objective of this work is to assess the captures and the impact of all fishing gear types used by the Saudi artisanal fishery on four marine megafauna groups: turtles, birds, dolphins, and dugongs ( Dugong dugon ). Nine questionnaire surveys were carried out from May 2013 to November 2014, covering a two-month period each. Ten main gear types were found to be used by 25 directed fisheries, including shrimp trawl, wire trap, hand line, troll, pelagic and demersal longline, and drift, surrounding, fixed, and set gillnets. Turtles were captured in relatively high numbers (4726 captures year −1 ) in nine directed fisheries, among which shrimp trawl fishery was responsible for 86.3% of the captures. The lowest capture rates were found with birds (13.1 captures year −1 ) and dolphins (7.4 captures year −1 ), related mainly with the Spanish mackerel longline and Indian mackerel surrounding gillnet fisheries. No dugong captures were recorded. In all, the Saudi artisanal fishery operating in the Arabian Gulf has a high impact on turtles and low impact on birds and dolphins. No impact on dugongs was reported during this study.

An attempt was conducted to understand the genetic population structure and historic demography of Indian mackerel, Rastrelliger kanagurta from Indian peninsular waters using mitochondrial DNA markers. A total of 241 sequences of mitochondrial control region and 271 sequences of mitochondrial ATPase gene region were amplified and analyzed in Indian mackerels collected from 10 different locations along Indian coast resulting in 123 and 155 haplotypes respectively. In addition, control region sequences representing samples from Thailand downloaded from NCBI were also used for analysis. Significant genetic differentiation (Φ ST value of 0.38; P ST values were not significant when analyses were carried out between samples collected from mainland India. Oceanographic and environmental barriers between mainland India, Portblair and Thailand contribute to limited larval dispersal and restricted mixing between populations resulting in subtle genetic differentiation. The lack of genetic subdivision between populations from mainland India indicates adequate gene flow and mixing within Indian waters. Bayesian skyline plots revealed a history of population expansion taken place approximately 10000 years ago coinciding with the time after the last glacial maximum or early Holocene. Intensification of monsoon events after the last glacial maximum or early Holocene along the Indian subcontinent contributed to increased productivity in the Tropical Indian Ocean and consequent demographic expansion of mackerel populations historically. Management measures for Indian mackerel populations could be devised regionally so as to conserve intra-specific diversity and biocomplexity of this important resource.

International audience; The mineral composition of target and non-target pelagic fish caught by purse-seiners and longliners in the western-central Indian Ocean was determined. From the ten essential elements analysed, selenium and zinc showed the highest concentrations in swordfish and blue marlin while Indian mackerel appeared as a good source of copper, iron and chrome. All catch had levels of lead and cadmium, two toxic elements, below the maximum sanitary limits. Although some concerns were raised regarding mercury concentrations in the largest species (wahoo, swordfish and blue marlin), molar ratios of mercury and selenium indicate that all oceanic pelagic fish from the western-central Indian Ocean are safe for human consumption. This study also gives insights on the relationships between the levels of essential and toxic elements in fish muscle and the size, trophic position and diet sources of the studied pelagic species.

Climate change impact varies at regional as well as species level and accordingly research needs to be focused on exploring the region-wise influence of oceanographic variations on key marine species. The present study depicts the annual and decadal fluctuations in Indian mackerel fishery along Kerala coast of southeastern Arabian Sea over a time period of 31 years (1985–2016), its relationship between four major oceanographic variables (SST, Pr, SSS and SSC) and future predictions under two Representative Concentration Pathways (RCPs). Coast specific changes of these oceanographic variables since 1960 provide a baseline status of the existing climatic conditions of the marine ecosystem of the SEAS whereas, the RCP projections till 2100 provide an insight to the future conditions. Generalized Additive Models (GAMs) has been used to comprehend the relation among the Weighted CPUE (cpue) and Relative effort (Effort) of Indian mackerel and the four major oceanographic variables. The GAM model could explain 68.9 % and 71.1 % deviance of cpue and Effort respectively. The significance of the most influential oceanographic variables on the cpue of Indian mackerel were in the order SST > Pr > SSC > SSS and for Effort were in the order Pr > SST > SSS > SSC. The projected cpue and Effort of Indian mackerel exhibits varying trends under the RCP 4.5 and RCP 6.0 scenarios. The future catch potential of Indian mackerel predicted under both RCP scenarios for the period 2020–2100 also show reduction, with the latter exhibiting a more drastic reduction. The study implies that for sustainable long-term fishery and to reduce the impact of climate change on Indian mackerel, the fishing pressure has to be maintained at low and healthy level.

The marine waters of Kerala state along the southwest coast of India are among the most productive upwelling regions in the southeastern Arabian Sea. Analyses were made to assess the impact of environmental changes on the marine fish catch using motorized and non-motorized craft operating off the coast. The catch per unit effort (CPUE) of total landings, OBGN (outboard gillnet), OBTN (outboard trawlnet), NM (non-motorized) crafts, as well as the catch of 5 major fish resources Indian mackerel, lesser sardines, Stolephorus spp., scads, and penaeid prawns were obtained. Sea surface temperature (SST), chlorophyll, salinity, rainfall, sea level anomaly, multivariate ENSO index, dipole mode index, local temperature anomaly, degree heating month (DHM), degree cooling month (DCM) and surface currents were used as variables to investigate the relationship between environment and fishery. Principal component analysis was used to select the minimum data set and GAM (Generalized additive model) was used to detect the influence of the environment on the fisheries. The adjusted R2 value of the GAM was 0.68, taking the CPUE of the total landings as the response variable. For the case of the selected fish resources, the adjusted R2 value of the GAM was 0.73 for penaeid prawns, followed by Stolephorus spp. (0.44), scads (0.33), lesser sardines (0.31), and Indian mackerel (0.25). Considering the CPUE as the response variable for the GAM also returned high adjusted R2 values for fishing method (OBGN = 0.59, OBTN = 0.53 and NM = 0.31). SST, chlorophyll, rainfall, salinity, yearly DCM and surface currents all had significant influences on the marine fisheries along the Kerala coast. Lower SST, high salinity and rainfall promote the fisheries of both small pelagics and large pelagic groups like scads. Along with the negative relationship between SST and fishery, the present analyses also indicate a positive relationship with yearly DCM, which clearly indicates that the warming of coastal waters has a negative impact on fisheries along the Kerala coast. From these results, we find that ocean currents can play a crucial role in fish recruitment in the coastal waters of Kerala. Primary production, the key factor for marine fishery production, was found to be controlled by environmental factors like SST and currents. These results point to the vulnerability of the small-scale fisheries sector of the tropical upwelling zone to increasing SST and climate change.

Toxic metals that bioaccumulate and magnify along food chains are a concern to human health worldwide. This study determined heavy metal concentrations in three commercial fish species; viz: whitespotted rabbitfish (Siganus sutor), thumbprint emperor (Lethrinus harak), and the Indian Mackerel (Rastrelliger kanagurta) from Kunduchi fish market in Dar es Salaam, Tanzania, assessed potential risks to human health, and the suitability of their fins as a non-destructive monitoring organ. Metal concentrations in fish muscle differed significantly among fish species as a result of their diverse ecological needs, metabolism, feeding habits, and habitats. The results also indicated that fish fin may not be a very good non-destructive monitoring organ for most metals, but can be used selectively for some metals and fish species. The levels of metal intake (aluminum (Al), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb) and zinc (Zn)) in fish muscles were below the FAO/WHO maximum levels for contaminants and toxins in foods for human consumption except for arsenic (As) which were higher than the recommended levels in Lethrinus harakand Rastrelliger kanagurta. It is recommended to reduce the amount of L. harakand R. kanagurta in daily meals of especially fishers and coastal communities who may eat fish up to three meals daily. Recommendation for further studies is provided.

A handheld, portable and non-destructive instrumental sensor was developed to assess the freshness of Indian Mackerel (Rastrelliger kanagurta) stored under ice. The freshness sensor consists of a webcam, raspberry-Pi (small single-board computer), LCD display and a power bank. The color changes in fish eye as a result of spoilage during iced storage was measured as pixel count using image processing technique. Simultaneously, destructive fish quality and freshness results were obtained by estimating K-value and Psychrophilic count during the storage. Multiple linear regression analyses were performed to assess the relationship between pixel count and quality indicators. The analysis of results of K-value and Psychrophilic count revealed that fish quality and freshness limits can be established in storage days as extremely fresh up to third day, fresh till thirteenth day and then spoiled. Further, these quality limits were correlated with pixel count against storage days to establish three different ranges in pixel count. The obtained pixel count ranges were provided as input to the sensor for classification of fish samples into three indicative freshness levels i.e. Extremely fresh, Fresh and Spoiled. The validation study of sensor was conducted by assessing fish samples collected from local markets and observed that sensor was accurately predicting the freshness of fish.

Twenty-three metals were evaluated in Indian Mackerel (Rastrelliger kanagurta) collected at nine fishing settlements along the coastal waters of Visakhapatnam. The muscle tissue was analyzed for metals using 7700 Series ICP-MS. The metal concentration obtained was in the order of Al > Fe > Zn > Cr > Sr > Mn > Cu > As > Se > Rb > Ag > Ba > Pb > Ni > V > Li > Cs > Cd > Co > U > Ga > Be > Ti in all samples. Most of the heavy metals were within the prescribed norms of the FAO, WHO, EC, and MHSAC, except for Al (34.66–58.55 μg/g), Cr (2.62–3.24 μg/g), Mn (0.86–1.36 μg/g), As (0.67–1.47 μg/g), and Pb (0.06–0.37 μg/g). The study reveals that the fish are not entirely safe for consumption and the pollution levels are on the borderline but can be remedied.

The present study investigates the use of a novel icing medium containing aqueous extract of two varieties of Garcinia fruit rinds, the culinary spices exhibiting antioxidant and antimicrobial activities, for the preservation of fish during chilled storage. Aqueous extracts of Garcinia indica and Garcinia cambogia were prepared and its phenolic content, antioxidant activities and antimicrobial properties were studied. Four icing media were prepared with 500 mg/L and 750 mg/L concentrations for each varieties of Garcinia extract. Conventional ice made of potable water was used as the control. The chilled fish was evaluated for the changes in pH, volatile basic compounds, oxidative parameters and total viable counts and the results were compared with those of sensory analyses. Mackerel stored in ice, prepared with different concentrations of garcinia extracts significantly reduced the values of trimethyl amine, total volatile basic nitrogen, peroxide value, thiobarbituric acid reactive substances and total viable counts compared to conventional icing. The shelf life of fish stored in ice as indicated by the results of sensory evaluation was observed to be 15 days, 21 days and 24 days under conventional icing system, ice containing Garcinia indica extract and ice containing Garcinia cambogia extract respectively.

Aside from having an important ecological role in the ocean food web, small pelagic fishes have become the major food source in the Sulu-Celebes Sea (SCS) which is bordered by Indonesia, Malaysia and the Philippines. Conservation and management of these fishes are of prime importance because the people living around the SCS are highly dependent on these resources. Nevertheless, basic biological information, especially relating to genetic diversity, population genetic structure, and demographic patterns, are often deficient. In this study, population genetic methods were used to investigate the genetic structure and diversity as well as historical demography of four ecologically and economically important small pelagic fishes in the SCS: Auxis thazard (Lacepede, 1800); Bali sardine, Sardinella lemuru (Bleeker, 1853); Indian mackerel, Rastrelliger kanagurta (Cuvier, 1816); and bigeye scad, Selar crumenophthalmus (Bloch, 1793). Fish samples were collected from 5 geographic locations: (Philippines: Zamboanga, Tawi-Tawi and Palawan; Indonesia: Manado; and Malaysia: Kudat) around the SCS and muscle tissues were sequenced for the mitochondrial DNA (D-loop) control region ( n = 150, 231, 169 and 224 for AT, SL, RK, and SC, respectively). Low overall F ST values, high haplotype diversity but low genetic differentiation among haplotypes, and highly mixed clusters from BAPS analysis indicate no distinct genetic population structuring among the samples. Furthermore, neutrality tests, mismatch analysis and Bayesian skyline plots suggest population expansion for all species. Generally, these results indicate that the four marine pelagic species are very resilient over evolutionary time scales; yet, proper management is very necessary, especially because overexploitation of small pelagic fishes has already been reported in the SCS region.

Histamine, putrescine cadaverine and cis-urocanic acid (UCA) have all been implicated or suggested in scombroid fish poisoning. However, there is little information on UCA especially during storage. Changes in their contents during storage of whole Indian mackerel at 0, 3 ± 1, 10 ± 1 for up to 15 days and 23 ± 2 °C for up to 2 days were monitored. Fresh muscles contained 14.83 mg/kg trans-UCA, 2.23 mg/kg cis-UCA and 1.86 mg/kg cadaverine. Histamine and putrescine were not detected. After 15 days at 0 and 3 °C, trans-UCA content increased to 52.83 and 189.51 mg/kg, respectively, and decreased to

Impacts of microbial transglutaminase (MTGase) (0-0.6 units/g sample) on gel properties of Indian mackerel unwashed mince, surimi and protein isolates with and without prewashing were studied. Generally, lower myoglobin and lipid contents were found in protein isolate with and without prewashing, compared to those of unwashed mince and surimi (P0.05). Protein isolate had the decreased Ca(2+)-ATPase and protein solubility, indicating protein denaturation. When MTGase was incorporated, breaking force and deformation of all gels markedly increased, especially as MTGase levels increased (P0.05). At the same MTGase level, gel from protein isolate with prewashing exhibited the highest breaking force and deformation (P0.05). The addition of MTGase could lower the expressible moisture content of most gels. No change in whiteness of gel was observed with the addition of MTGase (P0.05), but gel from protein isolate gels had decreased whiteness as MTGase at high level was added. The microstructure of protein isolate gels without prewashing showed a similar network to unwashed mince gels, whilst a similar network was observed between surimi gel and gel from protein isolate with prewashing. Nevertheless, a larger void was noticeable in gels from protein isolates. All gels incorporated with MTGase (0.6 units/g) showed a slightly denser network than those without MTGase. Thus, gel with improved properties could be obtained from protein isolate from Indian mackerel with added MTGase.

Impact of different pretreatments on chemical compositions of Indian mackerel mince was studied. Mince prepared using washing/membrane removal/alkaline solubilisation process (W-MR-Al) contained the lowest remaining myoglobin and haem iron content and also showed the lowest total lipid and phospholipid contents. When mince and W-MR-Al were hydrolysed using Alcalase for up to 120 min, a higher degree of hydrolysis (DH) was found in W-MR-Al after 30 min of hydrolysis. Furthermore, hydrolysate from W-MR-Al had lower peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and non-haem iron content throughout hydrolysis period (P0.05). When hydrolysate powder produced from mince and W-MR-Al (0-0.3%w/v) were fortified in milk, the former resulted in the lower likeness score (P0.05) at all levels used. The addition of the latter, for up to 0.2%, had no effect on likeness of all attributes, compared with milk without fortification (P0.05). Therefore, the appropriate pretreatment of mince yielded hydrolysate with lower fishy odour.

The total oil was extracted from the ground skin of Indian mackerel (Rastrelliger kanagurta) using various techniques of supercritical fluid extraction (SFE) at 20–35 MPa and 45–75 °C and by the Soxhlet method for comparison. The oil yield increased with pressure and temperature and the highest yields were 24.7, 53.2, 52.8, and 52.3/100 g sample (dry basis) for the continuous, cosolvent, soaking, and pressure swing techniques, respectively, at 35 MPa and 75 °C. The yield from the Soxhlet extraction was 53.6/100 g sample (dry basis). The CO2 consumption was 581.8, 493.6, 484.9 and 290.9 g for the continuous, cosolvent, soaking and pressure swing techniques, respectively, at 35 MPa and 75 °C. The largest recoveries of PUFA, especially the ω-3 family, were achieved from the soaking and pressure swing techniques at 35 MPa and 75 °C. Thus, the pressure swing and soaking techniques are the most effective at extracting the oil from fish skin.

Fatty acid compositions of fish oil extracted from different parts of Indian mackerel (Rastrelliger kanagurta) using various techniques of supercritical carbon dioxide (SC-CO2) at optimised conditions (35 MPa, 60 °C, 2 ml/min) were analysed and compared to the results of Soxhlet extraction. The amount of polyunsaturated fatty acids (PUFA) recovered (as a percentage of total extracted fatty acids) were within the ranges of 73.24–74.68% in the skin, 68.36–69.37% in the flesh, 56.20–57.3% in the viscera and 61.21–62.09% in the heads. The greatest amount of the ω-3 fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were found in fish skin followed by flesh, heads and viscera. The greatest amounts of EPA (9–12%) and DHA (10–14%) were obtained using the soaking and pressure swing techniques. The pressure swing and soaking techniques are the most effective techniques for extracting the ω-3 family of fatty acids from fish samples.

Pelagic fish stocks in the Java Sea have been exploited intensively since the beginning of the 1970s. However, due to the effect of increased fishing power of the fleets and the changing nature of spatial and temporal distribution of the fishing effort, assessment of stock trends based on commercial data of catch and effort requires the standardization of both effort and catch data. Here we present the first attempt to reconstruct a standardized time series of commercial catch per unit of effort (CPUE) for the main pelagic species exploited by the purse seine fleet in the Java Sea. The results showed that all the stocks analysed have largely declined since the beginning of the 1990s. For bigeye scad, Indian mackerel and sardine, current estimates are only between 3 and 19% of the maximum observed value while round scads and spotted sardine biomass estimates lie between 18 and 34%. However, our assumptions about the effect of lamp power and level of creeping and the fact that the influence of fish density on catchability and the effect of targeting were not taken into account thus observed decline is a rather conservative estimate of the real decline of the stocks. If effective management actions are not put in place as a matter of urgency in the Java Sea for small pelagic fisheries, one runs the risk of adding those species to the long list of overexploited stocks of the world oceans.

A consumer survey identified 10 species of most-preferred marine fish for daily consumption in Malaysia. Total lipids extracted from 10 species of the selected fish were analyzed for their total fat, fatty acids composition and cholesterol content. Most of the fish contained less than 6% lipid by weight and total cholesterol content was 37.1–49.1 mg/100g. The composition of fatty acids showed that total ω-3 poly unsaturated fatty acids (ω-3 PUFA; 29.7–48.4%) were the highest, followed by other PUFA (27.7–40.0), ω-6 PUFA (11.0–20.0%), saturated fatty acid (3.63–11.4%), and finally, mono unsaturated fatty acid (MUFA; 1.37–9.12%). All samples showed a much higher content of ω-3 PUFA when compared to standard menhaden oil. Most of the fish had a higher ω-3/ω-6 ratio (2.16 –4.14) than the standard menhaden oil (2.03) except for Four Finger Threadfin (1.50), Indian Mackerel (1.67) and Striped Sea Catfish (1.78). The ratio of PUFA/saturated of the samples ranged from 5.49 to 25.2.

Aliphatic hydrocarbon residues were monitored in two fish species, Indian mackerel (Rastrelliger Kanaguria) and Indian scad (Decapterus russelli) collected from local markets in three different cities in Oman. Residues were also monitored in water samples collected from two sites of the Gulf of Oman. Sampling was conducted twice, in July and again in February to have a thorough understanding of the dynamics of aliphatic hydrocarbon residues. Results indicated the presence of petrogenic aliphatic hydrocarbons ranging from C12–C28 in fish and water samples alike. Fish and water chromatograms were characterized by an unresolved complex mixture (UCM), a confirmatory sign of petrogenic origin of monitored hydrocarbons. Residue levels showed some variations related to sampling sites and time of sampling.

Iced storage of five commercially important species of tropical fish, namely oil sardine ( Sardinella longiceps (Valenciennes)), Indian mackerel ( Rastrelliger kanagurta (Cuuvier)), pearl spot (green chromide) ( Etroplus suratensis (Bloch)), milk fish ( Chanos chanos (Forsskal)) and tilapia ( Oreochromis mosambica (Peters)) was studied. Oil sardine and Indian mackerel had an acceptable iced storage shelf life of nearly 1 week and pearl spot, milk fish and tilapia nearly 2 weeks. During storage in ice there was a selection of bacterial types, and by the time incipient spoilage was noticed one or two species of bacteria constituted the bulk of the flora. In all these fishes, the spoilage flora were composed mainly of a single genus of bacteria, namely Pseudomonas .