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The present study aims to determine the proximate, fatty acid and amino acid profiling of consumed fresh narrow-barred Spanish mackerel (Scomberomorus commerson). Landed fish were freshly sampled (total length 33.7-48.7 cm and weight 617-1260 g) from the Yumurtalık Bay (north-eastern Mediterranean Sea) in Turkey during January, February and March. The protein values were highest in January (22.89%) while the and lowest in February (21.38%) and March (21.73%). Lipid and ash values were not significantly differencing among sampling time. The fatty acid data revealed that the saturated fatty acid values were found higher than the polyunsaturated and monounsaturated fatty acid values. In general, the fillets were abundant in palmitic acid (C16:0), stearic acid (C18:0), oleic acid (18:1n-9) and docosapentaenoic acid (C22:6n-3; DHA) values, regardless of the sampled months. DHA value was recorded as 315.08 mg 100g-1 in January, while it increased to 327.55 mg 100g-1 in the March samples. A total of 16 amino acids were determined from the fresh fillets. Compared with the other essential amino acids, the concentration of lysine and leucine were found to be higher in the fillet. At the same time, the lower rates of tryptophan were detected in examined samples for all months. Consequently, this study shows that the narrow-barred Spanish mackerel as a finfish (commercially valuable) from the north-eastern Mediterranean Sea has precious nutritional values that of the protein, fatty acids and amino acids during the sampling period. This fish can be recommended in terms of detected essential fatty acid and amino acid profile that completely nutritious for the human as well as other organisms’ dietary requirements.

In response to perceived, but unknown variation among the size selection of narrow-barred Spanish mackerel (Scomberomorus commerson) by artisanal gillnetters off Iran, and the need for such data to control exploitation as a precursor to balanced harvesting, the effects of two common mesh sizes (130 and 140 mm stretched mesh opening made from multifilament twine) on catches were investigated over one fishing year (nine months encompassing autumn to spring). Both mesh sizes mostly caught S. commerson at fork lengths (FL) larger than mean sizes at maturity (>67 cm), with the mean size selection incrementally increasing in the 130-mm mesh gillnet from autumn, and especially during spring. The greater selection occurred concurrent with an increasing condition factor (CF) among S. commerson, which typically spawn in late spring/early summer. Conversely, the relative size-selection of the 140-mm mesh gillnet decreased in spring, attributed to increasing CF precluding the capture of larger fish. Such seasonal variation in size selection might be countered by increasing mesh size to ~145 or 150 mm in spring. However, the existing 140-mm mesh might positively affect stock biomass by allowing larger, more fecund fish to avoid capture during spawning. The data support the strong influence of biological and environmental factors on gillnet size selection, which might also extend to other migratory, pelagic species.

Iranian coastal fishers targeting narrow-barred Spanish mackerel (Scomberomorus commerson) recently replaced their historical multifilament gillnets with those made from monofilament, evoking management concerns over potential increases in catch-per-unit-of-effort. During 20 fishing days, we compared catches from replicate surface-set gillnets that were identical in terms of mesh size (140 mm stretched opening), length (180 m), depth (30 m), hanging ratio (0.56) and spatio-temporal deployment, but had different materials: multifilament (1.8-mm diameter twisted twine) vs monofilament (0.8-mm diameter twine). Compared with the multifilament gillnet, there was a trend of greater catches (up to 1.3×) of S. commerson and another retained species, mackerel tuna (Euthnus affinis), along with one discarded species, giant catfish (Netuma thalassina) by the monofilament gillnet. However, statistical significance was restricted to E. affinis catches and a bias towards smaller S. commerson. These differences were attributed to species-specific catching mechanisms within gillnet material, with larger S. commerson retained by their teeth in the multifilament and all E. affinis more securely retained by their deeper bodies in the monofilament. Gillnet materials require regulation to preclude excessive effort on fully exploited stocks of species such as S. commerson.

espanolSe capturaron ejemplares inmigrantes de carita estriada del Pacifico y de carita oeste–africana y otros ejemplares con un aspecto externo intermedio entre estos progenitores putativos en la bahia de Abu Qir, al este de Alejandria, en Egipto. Los resultados del analisis univariado y multivariado del indice de hibridacion indicaron que existia hibridacion natural entre las especies parentales previstas. La funcion discriminante permite determinar si un determinado ejemplar del que se tienen datos pertenece a uno de los tres grupos y calcular su tasa de exito. Las distancias cuadradas de Mahalanobis obtenidas entre los grupos analizados indicaron que los tres grupos estaban claramente diferenciados y que las distancias entre los hibridos y Scomberomorus tritor eran superiores a las de los hibridos y S. commerson. Los valores medios del factor de condicion de los ejemplares hibridos fueron significativamente mayores que los de S. commerson; ademas, la mortalidad natural de los hibridos fue significativamente inferior a la de los progenitores exoticos (S. commerson), lo que indica que las condiciones ambientales de la region estudiada son mas adecuadas para el tipo hibrido que para las especies parentales invasoras. EnglishImmigrant 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 hybrid 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 specie

The contamination of seafood like narrow-barred Spanish mackerel (Scomberomorus commerson) fillets by potentially toxic elements (PTEs) has converted to worldwide health concerns. In this regard, the related citations regarding the concentration of PTEs in fillets of narrow-barred Spanish mackerel were collected through some of the international databases such as Scopus, Cochrane, PubMed, and Scientific Information Database (SID) up to 10 March 2020. The concentration of PTEs in fillets of narrow-barred Spanish mackerel fish was meta-analyzed and the health risk (non-carcinogenic risk) was estimated by the total target hazard quotient (TTHQ). The meta-analysis of data indicated that the rank order of PTEs in fillet of narrow-barred Spanish mackerel was Fe (10,853.29 μg/kg-ww) > Zn (4007.00 μg/kg-ww) > Cu (1005.66 μg/kg-ww) > total Cr (544.14 μg/kg-ww) > Mn (515.93 μg/kg-ww) > Ni (409.90 μg/kg-ww) > Pb (180.99 μg/kg-ww) > As (93.11 μg/kg-ww) > methyl Hg (66.60 μg/kg-ww) > Cd (66.03 μg/kg-ww). The rank order of health risk assessment based on the country by the aid of TTHQ for adult consumers was Malaysia (0.22251) > Philippines (0.21912) > Egypt (0.08684) > Taiwan (0.07430) > Bahrain (0.04893) > Iran (0.03528) > China (0.00620) > Pakistan (0.00316) > Yemen (0.00157) > India (0.00073). In addition, the rank order of health risk assessment based on the country by the aid of TTHQ for child consumers was Malaysia (1.03838) > Philippines (1.02257) > Egypt (0.40523) > Taiwan (0.34674) > Bahrain (0.22832) > Iran (0.16466) > China (0.02892) > Pakistan (0.01474) > Yemen (0.00731) > India (0.00340). Therefore, the children in Malaysia and the Philippines were at considerable non-carcinogenic risk. Hence, approaching the recommended control plans in order to decrease the non-carcinogenic risk associated with the ingestion of PTEs via the consumption of narrow-barred Spanish mackerel fish fillets is crucial.

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.

The present study used mitochondrial DNA control region to investigate the genetic stock structure and phylogenetic relationship of 38 samples of Narrow-barred Spanish mackerel Scomberomorus commerson (Lacepede, 1800) from two sites (Dar es Salaam and Pangani) located along the northern Tanzanian coastal waters. The study revealed that the Narrow-barred Spanish mackerel were characterized by high levels of mitochondrial DNA genetic diversity, at both haplotypes and nucleotide levels which is indicative of a large population size. The Analysis of Molecular Variance (AMOVA) test gave a significantly low F S T value ( F S T = 0 .0011), suggestive of a lack of genetic differentiation between the fish populations of the two investigated sites ( p = 0 . 925 ). Furthermore, AMOVA analysis showed that 99.50% of the total molecular variance was distributed within the populations, while only 0.5% was distributed between the populations. The Median-Joining network revealed a star-like median network, suggesting that the collected samples had similar evolutionary history and characterized by a recent historical population expansion. The present study recommends a single stock model for management of Narrow-barred Spanish mackerel in the northern coastal waters of Tanzania. However, due to the migratory nature of the species, a co-management initiative between coastal states within the Western Indian Ocean (WIO) region along with further studies focused on acquiring detailed information on the genetic stock structure covering the entire area is being recommended.

Food modification by adding vegetables to popular local foods such as pempek is expected to help overcome low vegetable consumption. This study aimed to develop pempek products made from narrow-barred spanish mackerel (Scomberomorus commerson) with the addition of broccoli (Brassica oleracea var. Italica) and red cabbage (Brassica oleraceavar. Capitata forma rubra). It was an experimental study with a completely randomized design (CRD). There were 4 formulas for each type of pempek, F0 (0% vegetables), F1 (20% vegetables), F2 (40% vegetables), and F3 (60% vegetables). Based on the assessment of 25 semi-trained panelists using a Visual analog scale instrument on color, aroma, texture, taste, and aroma, both broccoli and red cabbage affected and increased significantly (p 0.05). Through the texture analyzer instrument, the selected formula of vegetable pempek with the highest sensory acceptance (broccoli pempek F3 and red cabbage pempek F3) together with control pempek was declared to have a chewy texture. Based on Hunter’s color notation, it was revealed that the control pempek was brownish-white, the broccoli pempek was greenish-brown, and the red cabbage pempek was purple. Then, the addition of vegetables at the level of 60% affected the chemical properties of both vegetable pempek, in the parameters of water, ash, protein, carbohydrates, and dietary fiber, at α = 0.05. The three types of pempek did not show any difference in fat level due to the very low-fat content. Thus, vegetable pempek can be used as an alternative food to improve vegetable consumption.

The narrow-barred Spanish mackerel Scomberomorus commerson is one of the most important linefish species caught in KwaZulu-Natal and southern Mozambique waters, forming the basis of important commercial, artisanal and recreational fisheries. A total of 439 S. commerson were sampled along the east coast of southern Africa (KwaZulu-Natal, South Africa, and southern Mozambique) between April 2011 and March 2012. Retrospective length-at-age data observed from whole otoliths were used to compare and describe sex-specific growth. Growth rates obtained from otolith-derived data were compared with those estimated from 29 tag-recaptured fish. Overall, ages ranged from 0.48 to 14.6 years for females and 0.4 to 13.57 years for males. Otolith readings yielded an average percent error of 11.21%, lower than recorded in a previous study from the region. Marginal zone analysis provided strong evidence that one translucent and one opaque growth zone were laid down annually. Schnute growth-function parameters indicated significant differences in growth between sexes. Females approached their mean asymptotic length at a faster rate, and grew to a greater mean length-at-age, relative to males. Growth in both sexes was rapid, achieving 67.46 cm FL (females) and 65.4 cm FL (males) in their first year of life. Growth rates obtained from tag-recaptured S. commerson indicated slower growth for smaller/younger fish up until 70 cm FL after which growth was very similar to that observed from otolith-derived data. The results of this study provide accurate, validated life-history parameters for king mackerel that are important for the assessment of stock status in the region.Keywords: back-calculation, growth estimates, otolith ageing, recreational fishery, Schnute model, Scombridae, sex-specific growth, tag-recapture data

The phylogeography of the narrow-barred Spanish mackerel (Scomberomorus commerson) in the Arabian Sea, Bay of Bengal, Indian Ocean, Java Sea, and South China Sea was investigated using sequence dat...

Population genetic structure of the pelagic narrow-barred Spanish mackerel (Scomberomorus commerson) was examined in 10 populations from the Indo-West Pacific region, based on mitochondrial control region DNA. We examined genetic composition of 56 individuals of S. commerson from the Arabian Sea, Bay of Bengal, and compared them with 40 individuals from previously published data sampled from the ROPME Seas area and South West Pacific Ocean. The overall nucleotide and haplotype diversities were estimated to be 0.072 and 0.995, respectively. Demographic parameters such as Tajima’s D and Fu’s F s statistics were negative, but non-significant across all the populations, except for New Caledonia in the South West Pacific, indicating a stable population of S. commerson in this region. To assess intra-specific patterns of connectivity, we constructed statistical parsimony networks among haplotypes and estimated time of most recent population expansion. AMOVA and F ST values among Indian and Arabian regions revealed non-significant variation among the populations, while separation was noted among the samples of the northern and eastern Indian oceans, as well as with South West Pacific. A parsimony network analysis provided evidence for four separate population segment/stocks in the Indian Ocean and Pacific Ocean, raising a conservation concern. Our results support a need for regional cooperation to ensure the sustainable exploitation of S. commerson in the Indo-West Pacific region.

Narrow barred Spanish mackerel is a high-value pelagic fish and is mostly caught in Bone Bay waters. These fish can be caught using purse seines, drift gill nets, lift net and hand lines, but the most catches are in drift gill nets and hand lines. This study aims to compare the performance of drift gill nets and hand line technologies. Biological, technical, social, economic and legal data were collected from 2018 to 2020 through direct field observations and interviews. Performance according to the four aspects and the combination of all aspects of the two fishing gear were analyzed using the Mangkusubroto Scoring method. Based on the biological and technical aspects the performance of the hand line was better than the drift gill nets, while on the contrary, based on the economic and social aspects, the performance of gill nets was better than the hand lines. Based on legal and institutional aspects, the two technologies do not show any differences. Although there are differences in the performance of the biological, technical, social and economic aspects, the performance of the two technologies is classified as good.

Genetic connectivity of narrow-barred Spanish mackerel (Scomberomorus commerson) from the South China, Bali and Java Seas was investigated using mitochondrial cytochrome b gene sequences. The nucleotide and haplotype diversities estimated among the gene sequences ranged 0.012–0.014 and 0.83–0.92, respectively. The phylogenetic analysis (Maximum Likelihood) of gene sequences indicated that the individuals sampled belong to a single taxonomic clade. The analysis of molecular variance (AMOVA) and FST values revealed non-significant variation among populations. Both Tajima’s D and Fu’s FS statistics were non-significant indicating an effective large and stable population size. The results suggested that the S. commerson population has strong genetic connectivity in the study regions. In addition, mismatch distribution analyses and tests of neutrality evolution indicated that S. commerson populations had not undergone significant sudden population expansion recently. Hence, the current study suggests t...

Pempek is known as one of the signature dishes from Palembang, South Sumatera, that is made of a mixture of fish and tapioca flour. Pempek is made through a long process such that the production time-consuming. Pempek premix flour (PPF) is made from a mixture of surimi powder, tapioca starch, and wheat flour, which can be used to make pempek instantly. This study aimed to determine the profile of PPF products based on physicochemical characteristics. This research was divided into two stages. The first stage was the process of making surimi powder from mackerel fish. The second stage was the process of making PPF and physicochemical analysis. The physicochemical characterization of PPF was conducted to obtain information on proximate content, yield, color (L*, +a, +b values), whiteness, gel strength, water absorption capacity (WAC), and microscopic structure. The result showed that PPF contained 12.18% of moisture, 18.3% of protein, 65.55% of carbohydrate, 2.27% of fat, and 1.69% of ash. The results of physical characterization showed that PPF has 97.8 lightness value (L), white color (a=2.7 and b=14.1), 85.8% whiteness value, 885.8 g.cm gel strength, and 1.25 ml/g WAC. Microstructure results showed that the PPF had a solid texture appearance with different particle sizes.

The narrow-barred Spanish mackerel (Scomberomorus commerson) is an economically important fish species in Taiwan. Nevertheless, its reproductive biology in the region is poorly understood. This study provides the first information on the reproductive biology of this species in the central Taiwan Strait. In total, 1031 specimens were collected from January 2016 through August 2017, and the sex ratio (0.55) was significantly different from 0.5 (p = 0.0016). On the basis of progressive changes in ovary size, ovary histology, oocyte diameter, and gonadosomatic index, the spawning season was estimated to extend from March through August, peaking between March and May. The fecundity (F) and batch F (BF) were estimated to range from 193,212 to 9,810,450 and 91,117 to 2,077,581 eggs per fish, respectively. The relationships of F and BF to fork length (FL) were estimated as follows: F = 0.0247FL4.005 (r2 = 0.57, n = 110, p = 1.05 × 10−10) and BF = 0.00071FL3.999 (r2 = 0.514, n = 41, p = 0.0000149). Based on a logistic model, sizes at 50% of maturity were 68.0 and 68.4 cm in FL for female and male specimens, respectively. Hydrated and postovulatory oocytes were collected from March through June, suggesting that the Taiwan Strait is a spawning ground for S. commerson. The proportion of reproductively active female fish with postovulatory oocytes during the spawning season was 0.15, indicating that spawning occurs every 6.5 days on average. The parameters measured in this study, which provide useful information about S. commerson, can facilitate management, conservation, and sustainable fishing of this species in the region.

In the present study, Scomberomorus commerson was collected during the period 2006-2011 in order to pro- vide information on the concentrations of eight heavy metals present in this marine species commonly consumed by the population and to have knowledge whether these levels may constitute a hazard to consumers. Liver showed high concen- trations of metals in the tissues and organs. Fe is the most accumulated in all tissues and organs. The highest mean con- centration of Fe (608.93+113.22 µg/g), Mn (9.79+4.22 µg/g), Cu (38.57+16.62 µg/g), Zn (53.25+26.50 µg/g), Ni (3.22+1.13 µg/g), Pb (1.20+0.64 µg/g), Cd (2.03+0.91 µg/g) and Cr (1.93 + 0.87 µg/g) was determined in liver of fish. The order of abundance of the metals in the fish samples based on concentrations in the muscle tissues analysed were as follows: Fe>Zn>Cu>Mn>Ni>Cd>Pb≥Cr. For the toxic metal, Pb was found to have lower concentration of the mean val- ues than the permissible limits set by FAO/WHO. However, Cd level was higher than the permissible limit and it can be concluded that the contamination of Cd in S. commerson may pose threat for the importers due to high per capita con- sumption of the fish.

Population dynamics parameters of Scomberomorus commerson in Bushehr area waters of Iran were analyzed between October 2011 and September 2012. Fork length frequencies were collected from the gill net commercial catch. Von Bertalanffy growth function was used to estimate growth parameters K and L∞. Instantaneous total mortality rate (Z), instantaneous natural mortality rate (M) and the instantaneous fishing mortality rate (F) were also calculated. Resource status was evaluated by comparing estimates of the fishing mortality rate with target (Fopt) and limit (Flimit) biological reference points. FiSAT program was used to assess growth and mortality parameters. Based on the growth curve analysis, growth parameters were: K=0.5year−1 and L∞=148cm. Instantaneous total mortality was Z=0.97year−1. The estimate of M=0.56year−1 and F=0.41year−1, resulting in an exploitation rate (F/Z) of E=0.42year−1. Target and limit biological reference points were: Fopt=0.28year−1 and Flimit=0.37year−1. Size at capture at probabilities of 0.25 (L25), 0.5 (L0.5) and 0.75 (L0.75), were 46.3 cm, 55 cm and 60.2 cm respectively. Longevity (Tmax) was calculated as 3/K equal to 6 years. The exploitation rate (E) did not indicate overfishing; however, Fopt and Flimit rates were lower than fishing mortality (F), suggesting that overexploitation occurred. Growth parameters in the present study showed that the gillnet fishery catches of S. commerson that are of ages 1 or 2, which may not have reached maturity. Gillnet mesh size can be a factor why the catch is composed of mostly small, immature fish. Therefore, changes in mesh size and net size should be considered.

Scomberomorus commerson were collected on weekly basis during January 2012 to December 2014 at Mangalore Fishing Harbour. Stomach of 214 narrow barred Spanish mackerel measuring from 48 to 105 cm fork length (FL) for males and 45.5 to 115 cm FL for females were analysed to study their feeding habits. Fish with empty stomach were prevalent in almost all the months. Prey mainly comprised of fishes and crustaceans, with the fish component forming 99.9%. The index of relative importance (IRI) showed that the dominant prey were semi-digested fish remains (44.6%) of Sardinella longiceps (30.1%), Decapterus sp. (18.7%), whitebaits (2.5%), Rastrelliger kanagurta (1.5%) and Epinephelus spp. (1.1%), while Saurida sp. (0.7%), Megalaspis cordyla (0.5%), Scombroides sp. (0.2%) and shrimps (0.1%) were found occasionally in the gut. Index of stomach fullness (SFI) was 0.11 in August and 0.65 in January. Generally, SFI was higher during September to January and lower during February to August. The empty stomach ratio (ESR) ranged from 33.3% (August) to 92.3% (April).

The narrow-barred Spanish mackerel (Scomberomorus commerson) is a large neritic predatory fish targeted by several thousand artisanal boats across eight jurisdictions in the Arabian Gulf, Gulf of Oman, and Arabian Sea. First steps have been taken for a regional management of the stock across some of these jurisdictions. However, although the drive for regional management may be justified on the grounds of probable transborder population processes, it may err by ignoring smaller spatial scales in the structuring of stocks that function as meta-populations. We carried out a comparative analysis of life history traits of the narrow-barred Spanish mackerel using newly collected data as well as published data encompassing a region from the northern Arabian Gulf to the eastern Arabian Sea. We obtained substantial differences in somatic growth and reproduction processes while rates of natural mortality were homogeneous. In addition we show differences in length composition of the catch reflecting different levels of exploitation. Our results imply that management should be conducted primarily at the level of each national jurisdiction while regional-wide initiatives could be useful to resolve scientific issues about population structure.

Narrow barred Spanish mackerel, Scomberomorus commerson (Lacepede 1800) is one of the commercially important fish in Indian waters. For sustainable management of the species, it is necessary to understand the genetic stock structure of the species. Accurate delineation of genetic stock structure can be achieved using nuclear microsatellite markers. A study was carried out to identify and validate polymorphic microsatellite markers in S. commerson using information available from closely related fish species. The study could identify 10 polymorphic microsatellite loci which can be effectively utilised for identifying genetic stock structure of the species. Validation of the identified loci was also done by testing the loci in natural populations of the species. The findings of the present study will be useful in devising stock-specific management measures for conservation and sustainable utilisation of this commercially important fish species in Indian waters.

In this research, size selectivity for narrow-barred Spanish mackerel (Scomberomorus commerson) and other species such as Indo-Pacific king mackerel (Scomberomorus guttatus), Longtail tuna (Thunnus tonggol),Kawakawa (Euthynnus affinis), Talang queenfish (Scomberoides commersonnianus) and John's snapper (Lutjanus johnii) were investigated in mesh sizes of surface, mid-water and bottom drift nets in coastal waters of Bandar Abbas and in the western part of Hormozgan province (fishing ports of Gong and Bustaneh), as well as of catch composition from the fisheries. The data required for the relevant analysis was collected for the years 2012-2014. In order to determine the size selectivity of the investigated species, cumulative probability distributions of retention girth (operculum and maximum girth) at length was used. The results indicated that there is a linear relationship between length (fork length or total length) and transvers morphometric parameters in six positions of girth at fish species. Seven types of gillnets with stretched mesh sizes of 70, 76, 79, 101, 114, 132 and 165 mm and different technical characteristics were investigated for size selectivity of S. commerson, in which the optimal length were 38, 44, 49, 63, 74, 86 and 100 cm FL in the respective meshes. The capture processes of S. commerson was mostly in wedging in the all mesh sizes, whereas in the other species, depending on the morphology of fish, the retention method was different. The comparison of length frequency distribution of kingfish with mean length at maturity (Lm50%) indicated that, depending on mesh size, the frequency of the immature fish in the catch was between 4 and 100%. On the basis of optimal length at mesh size, the minimum legal mesh size of kingfish was estimated as 162 mm. Size selectivity curve was also represented for other species, which depending on fish morphology the model was inadequate in fitting the data. The results from the catch composition showed that the species diversity is different by fishing method. In mesh sizes of 70, 76 and 79 mm, the kingfish was captured in target and bycatch species depending on time by the surface drift gillnet fishery operated by the fishing boats. In this type of gillnet fishery, bycatch accounted for more than half of the total catch in which some of the species was important economically. Catch composition in gillnet fishery operated by dhows was different depending on fishing method. At the first step, it is necessary to impose a ban on gillnets with mesh sizes of 70, 76 and 79 mm in second half of the year. In the next step, for establishing the regulation on minimum legal mesh size of kingfish, it needs to do further study in seas trails aimed at determine the appropriate mesh size. Also, in the multispecies fishery, it is necessary to do a research for optimization of mesh sizes of gillnets and to implement minimum legal mesh size for the main target species.

Although migratory pelagic fishes generally exhibit little geographic differentiation across oceans, as expected from their life-history (broadcast spawning, pelagic larval life, swimming ability of adults) and the assumed homogeneity of the pelagic habitat, exceptions to the rule deserve scrutiny. One such exception is the narrow-barred Spanish mackerel (Scomberomorus commerson), where strong genetic heterogeneity at the regional scale has been previously reported. We investigated the genetic composition of S. commerson across the Indo-West Pacific range using control-region sequences (including previously published datasets), cytochrome-b gene partial sequences, and eight microsatellite loci, to further explore its phylogeographic structure. All haplotypes sampled from the Indo-Malay-Papua archipelago (IMPA) and the southwestern Pacific coalesced into a clade (Clade II) that was deeply separated (14.5% nucleotide divergence) from a clade grouping all haplotypes from the Persian Gulf and Oman Sea (Clade I). Such a high level of genetic divergence suggested the occurrence of two sister-species. Further phylogeographic partition was evident between the western IMPA and the regions sampled east and south of it, i.e. northern Australia, West Papua, and the Coral Sea. Strong allele-frequency differences were found between local populations in the southwestern Pacific, both at the mitochondrial locus (ΦST=0.282-0.609) and at microsatellite loci (^θ=0.202-0.313). Clade II consisted of four deeply divergent subclades (9.0-11.8% nucleotide divergence for the control region; 0.3-2.5% divergence at the cytochrome b locus). Mitochondrial sub-clades within Clade II generally had narrow geographic distribution, demonstrating further genetic isolation. However, one particular haplogroup within Clade II was present throughout the central Indo-West Pacific; that haplogroup was found to be sister-group to an haplogroup restricted to West Papua and the Coral Sea, yielding evidence of recent secondary westward colonization. Such a complex structure is in sharp contrast with the generally weak phylogeographic patterns uncovered to date in other widely distributed, large pelagic fishes with pelagic eggs and larvae. We hypothesize that in S. commerson and possibly other Scomberomorus species, philopatric migration may play a role in maintaining the geographic isolation of populations by annihilating the potential consequences of passive dispersal.

Narrow barred Spanish mackerel,Scomberomorus commerson(Lacepede, 1800) is one of the economically important marine fish species in the Northern Indian Ocean. Genetic stock structuring is reported inS. commersonfrom Arabian Peninsula, Indo-West Pacific, Northern Australian, Southeast Asia and Northern Australia. The present study utilized microsatellite markers to elucidate the population structure ofS. commerson(Lacepede, 1800) in the Arabian Sea and Bay of Bengal. A total of 12 polymorphic microsatellite loci were amplified in 250 samples collected from five different geographic locations. LowFSTvalues (0.0023–0.027), AMOVA, PCoA and the Bayesian analysis of genetic structure indicated unit stock of the species in Indian waters. Bottleneck analysis using Wilcoxon signed rank tests and Mode shift test indicated lack of recent bottleneck events across populations ofS. commerson. The findings of the present study could be used in managing the commercially important species,S. commersonas a unit stock in Arabian Sea and Bay of Bengal of Northern Indian Ocean and reinforces the need for regional cooperation on fisheries management.

Reproductive biology, Diet and population dynamics parameters of narrow-barred Spanish mackerel, Scomberomorus commerson, in the Persian Gulf were studied during 2011-2012. Fork length frequencies were collected from the commercial catch and from the current fishery nets (gill nets with 9 and 14cm mesh size) at the landing places. During 5 periods in October, December, March, April and July 20-40 specimens were also purchased from the fishermen at several landing sites to investigate and recording of data for feeding and reproductive conditions. Fork length (FL) of 2742 fishes was recorded to the nearest cm and weight of the specimens were measured to the nearest 0.01kg. FiSAT program was used to assess growth and mortality parameters. Reproductive maturity stages were assessed macroscopically using a five element scheme based on gonad size and appearance. The numbers of ovaries were fixed and preserved in 10% formalin. Central sections were embedded in wax, sectioned Hematoxylin–Eosin stains. For this subset, gonad maturation was categorized histological using a simplified five-stage description scheme and compared with the macroscopic assessments for validation. A Gonosomatic index (GSI) was also calculated for each fish. Feeding condition results showed that, sardines are the major prey of S. commerson. Pony fishes, Haltbeak and Indian mackerel were observed in the stomach content. These preys can be assumed as a secondary or accidental food items. Liver Somatic Index (HSI) was maximum in April and minimum in July. The annual instantaneous rate of fishing mortality (F= 0.42 year^−1) was considerably greater than the target (Fopt= 0.28) and limit (Flimit= 0.37) biological reference points, suggesting that the stock is heavily overexploited. Feeding and nutrition results showed that sardines are the major items prey of king S. commerson. Ponyfish, haltbeak and Indian mackerel fishes were observed in diet that can be considered as secondary or accidental foods. Maximum and minimum of Kn index was in October (9.3) and in March respectively. Liver Somatic Index (HSI) was the highest rate in February (1.70) and the lowest in July (0.85) that indicated on the worst and the best condition of fish in the mentioned periods respectively. No difference was observed in the weight stomach index and weight index (SI) in two sexes and it was about 0.09. The smallest of fish was observed 17cm FL and the biggest was 152cm FL. The mean size of fork length frequency was observed from maximum108cm (SD= 24) in February to minimum 29.4cm (SD= 5.5) in September. Based on growth curve analysis, growth parameters, K and L∞ were estimated 0.23year^−1 and 156.45 cm respectively. Instantaneous total mortality (Z), was 1.13 year^−1 . The estimate of M was 0.43 year^−1 and thus, the estimate of F was0.7 year^−1 . This translates to an exploitation rate (F/Z) of 0.69 year^−1 . Target (Fopt) and limit (Flimit) biological reference points were calculated 0.17 year^−1 and 0.22 year^−1 respectively. The size at capture at a probability of 0.25 (L25), 0.5 (L.5) and 0.75 (L.75) was35.84 cm, 40.28cm and 61.98 cm respectively. Tmax was calculated as 3/K equal to 6 years. Matured females (Stages III, IV) were observed between mostly between April to July. By July, most fishes were in ripped and spent stages (StagesIV, V) indicating the end of the spawning season. The result of GSI avtivity in 153 male and female fish indicated the higest reproductive activity from April to July with the peak of July. The present study results shows that the highest of catch rate were done in 1 and 2 years olds of fish.Although exploitation rate have not indicated over fishing but Fopt and Flimit rates are less than fishing mortality that shows overexploitation was happened. Changes of the mesh size in thegillnet of 9cm and the size of the nets should be considered. Banning of the king mackerel catch in the June and July that is the spawning peak period can be helped to the brood stocks. Iranian Fisheries Science Research Institute Published

Summary A data base including length frequency distributions and catches of the Scomberomorus commerson in Oman according to fleet (gear/technique) and region has been established to carry out length cohort analyses, determine yield per recruit and simulate changes in fishing effort and/or increase in minimum length limit in catches. The analyse of data showed that: (i) The average fishing mortality rate is moderate (0.5–0.6), but acts in part on the juvenile fraction of the stock. The exploitation pattern differs, however, among fleets with some fleet components targeting largely immature kingfish and others largely the adult stock. (ii) An increase in total fishing effort would lead to long-term losses in total catch; the losses would be highest for fleets that target the larger specimens. A reduction of the effort would, in the long term, lead to an increase in yield and spawning stock biomass. (iii) An increase of minimum length limit in catches would, in the long term, lead to a substantial increase in yield and spawning stock biomass; the gain in catch would be largest for fleet components that target the adult fraction of the stock and (iv) an increase in minimum length limit in catches combined with an increased selectivity of the fisheries (i.e. favorising fleets targeting the adult fraction of the stock) would lead to the highest gain in sustainable catch. In this case, the sustainable catch could be increased by more than 50%. Therefore, this option represents the optimal management strategy obtained in the present study.

The status of the kingfish resource of Oman has been assessed using a per-recruit model noting that there are differences in growth and mortality between the sexes (amongst other parameters). It is estimated that at the current fishing mortality rate the spawning biomass per-recruit for females is 16% and that of males is 27%, indicating that the fishery is overfished, with a high chance of recruitment failure in the future. A number of management scenarios, based on minimum size limits and closed seasons were evaluated for this fishery in order to determine which of the scenarios would increase spawning biomass per-recruit without compromising yield per-recruit harvest rates to levels which may lead to socio-economic hardship amongst fishers. It has been shown that closed seasons and minimum size limits may be the most effective current means of achieving these objectives and it is proposed that a closed season, coupled with a minimum size of 45 cm (FL) for both sexes, be implemented each year from the 1 March to 30 April. This would increase spawning biomass per recruit to 29% for females and 40% for males, when compared to an unfished state and over the long-term.

We studied the genetic stock structure of Scomberomorus commerson (locally called kingfish) using restriction fragment length polymorphism (RFLP) and direct sequencing analyses of mtDNA samples from seven locations within the ROPME sea area (Arabian Gulf, Gulf of Oman, and Arabian Sea). A 475-bp segment from the D-loop region was screened in 218 samples using six restriction enzymes, resulting in 22 composite haplotypes. Mean nucleotide diversity for the seven populations was 0.025 (±0.000). An AMOVA comparison among groups of individuals inside and outside the Gulf showed 0.49% variation (p = 0.201), whereas the variation of populations within these groups was 0.05% (p = 0.408). The mean FST value for population pairwise comparisons was 0.010. To further resolve genealogies, sequence analysis was performed on a 330-bp fragment from the same segment for 193 fish. The genetic variance estimated across all populations was similar to the RFLP data, indicating a homogeneous distribution consistent with a single intermingling genetic stock. Based on the genetic marker tested, the null hypothesis that kingfish within the ROPME sea area constitutes a single stock cannot be rejected, but considering that a few migrating fish can reduce heterogeneity to where genetic drift is undetectable, panmixia cannot be confirmed. The results cautiously suggest that adopting a single-stock model and regional shared management are appropriate for sustainable long-term use of this important resource. More rigorous genetic testing using additional neutral markers, and mark-recapture experiments to detect spatial movement patterns, are recommended to further elucidate any stock substructure.

The population biology and fishery for Scomberomorus commerson in the southern Arabian Gulf were investigated using a combination of size frequency, biological and size-at-age data. Transverse sections of sagittal otoliths showed structural increments consisting of alternating translucent and opaque bands, which were used to estimate age. Edge analysis revealed an annual periodicity of formation with opaque zones being deposited between May and July in association with increasing seawater temperatures. The maximum absolute age estimates were 16.2 years (males) and 15.3 years (females). Initial growth was rapid with fish reaching more than half the asymptotic size by their second year and there were no significant differences in growth characteristics between sexes. Parameter values of the von Bertalanffy growth function fit to size-at-age data (males and females combined) were: k = 0.21, L∞ = 138.6 cm (LF) and t0 = −1.9 years. Spawning occurred between April and August, the mean sizes and ages at first sexual maturity were 72.8 cm LF (1.9 years) for males and 86.3 cm LF (2.1 years) for females. The size at which fish were fully recruited to the fishery (62.6 cm LF) was considerably smaller than both the mean size at first sexual maturity for females and the size at which yield per recruit would be maximised (95.6 cm LF). Furthermore, the annual instantaneous fishing mortality rate of 0.62 year−1 (0.46–0.79 year−1 95% CI) was by far in excess of the precautionary target (Fopt = 0.13 year−1) and limit (Flimit = 0.17 year−1) biological reference points, indicating that the resource is heavily over-exploited. The results suggest that an increase in mesh size regulations for gillnets in combination with a substantial reduction in fishing effort will be required if resource conservation and stock rebuilding objectives are to be achieved. The study also highlights the need for a strategic regional approach to the assessment and management of this highly migratory species.

Age and growth parameters were determined for the kingfish ( Scomberomorus commerson ) at six locations in the Sultanate of Oman. During 2 years of sampling, 1244 kingfish were collected, from which 962 sagittal otoliths were sectioned and read. The fishery is characterized by a prevalence of 0+, 1+ and 2+ year classes, which made up approximately 90% of the total fish collected. Maximum fork lengths, weights and ages for all sexes combined were 166 cm, 40.4 kg and 20 years, respectively. Sex specific differences were evident in length, weight and growth. Growth parameters show that female S. commerson ( L ∞ = 140.44, K = 0.309, t 0 = −1.501) grew at a slower rate but reached a greater asymptotic length than male fish ( L ∞ = 118.80, K = 0.595, t 0 = −0.730). There were significant differences in growth between regions with Ash-Sharqiyah recording the greatest asymptotic length ( L ∞ = 172.82) and Al-Wusta the lowest ( L ∞ = 122.596). Fish from Al-Wusta also grew at a much greater rate ( K = 0.796) than those from the other five regions. A comparison of VBGF values using length frequency data and age at length data at one region, Muscat, revealed differences in all three growth parameters. Catch curves reveal large differences in total mortality ( Z ) between geographic regions, with the highest recorded at Al-Batinah (1.321 year −1 ) compared with 0.405 year −1 at Muscat. Large discrepancies in age structure, growth parameters and annual mortality between regions suggest overexploitation of this species may have already occurred in places like Al-Batinah and Dhofar. However we recommend that mortality estimates ( Z , M and F ) be used with caution until catch curve data for different fishing gear is made available.

Patterns of reproduction and spawning were determined for the kingfish (Scomberomorus commerson, Lacepede) in two oceanographic regions of the Sultanate of Oman. During 2 years of sampling, 1264 fish were purchased from fishermen at landing sites along the Arabian Sea and the Gulf of Oman. Sizes of males and females were similar in both regions but more females were caught along the Gulf of Oman than along the Arabian Sea coast. Females matured at a significantly smaller length and about 2 months earlier than males in both regions. For both sexes, the fish collected along the Arabian Sea matured approximately 10 cm smaller and 6 months earlier that those of the Gulf of Oman. Analysis of the reproductive stages and gonosomatic index revealed a single yearly reproductive cycle beginning in February and ending with a single spawning period in May–June, just prior to the onset of the summer oceanographic regime. Reproductive stages and growth also indicated that 40% of the landings along the Arabian Sea is composed of fish before their first reproduction (Stage I) whereas along the Gulf of Oman, only 25% of the fish were caught before entering active reproduction. Several indicators suggest that kingfish stocks are under intense pressure and that management of this species should be implemented rapidly if they are to remain sustainable.

The parasite fauna of Spanish mackerel Scomberomorus commerson from 10 sites across northern Australia and one site in Indonesia, was examined to evaluate the degree of movement and subsequent stock structure of the fish. Kupang fish (Indonesia) had very few Terranova spp., Grillotia branchi, Otobothrium cysticum or Pterobothrium sp. compared to Australian fish, indicating that no Australian fish enter the Kupang fishery. Univariate and discriminant function analysis of four ‘temporary’ parasite species, the copepod Pseudocycnoides armatus and the monogeneans Gotocotyla bivaginalis, Pricea multae and Pseudothoracocotyla ovalis, demonstrated little similarity between areas of northern Australia, indicating minimal short-term exchange between neighbouring groups of S. commerson. Analyses of five ‘permanent’ parasite species, the larval helminths G. branchi, O. cysticum, Pterobothrium sp., Callitetrarhynchus gracilis and Paranybelinia balli, also revealed large differences between areas thus indicating long-term separation. There are at least six parasitological stocks across northern Australia: Fog Bay/Bathurst Island, Cape Wessel, Groote/Sir Edward Pellew, Mornington Island, Weipa, and the Torres Strait. The occurrence of a few irregular fish in the samples suggested that up to 5% of fish moved between stocks during their lifetime. The similarity of within-school variability to that between schools showed that the fish do not form long-term school associations.

Data from permanent parasites (juvenile trypanorhynchs and anisakids) indicated that Spanish mackerel Scomberomorus commerson from four sites on the west coast of Australia, Abrolhos, Shark Bay, Exmouth and Onslow, intermingled and were probably all drawn from the same stock. Fish from Broome, Kupang (Indonesia), Groote Eylandt-Torres Strait and the cast coast of Australia had distinct faunas of permanent parasites and probably each belonged to a different stock. There was evidence of movement of fish between Broome and the west coast. Abundances of temporary parasites (gill copepods and monogeneans) suggested that males and females on the west coast migrated separately because in several cases the parasite fauna of one sex was more similar to that of fish in an adjacent area than to the opposite sex in the same area. (C) 2001 The Fisheries Society of the British Isles.

Length composition data from quarterly catches of Omani narrowband Spanish mackerel, Scomberomorus commerson (Lacepede), landed between 1987 and 1995 were used to estimate the growth, mortality and exploitation parameters of the stock. Non-linear least square fitting provided a complete set of von Bertalanffy growth estimates: L∞ = 173.6 cm fork length; K = 0.28; and t0 = −0.86 years. There were no seasonal differences among the growth estimates. The instantaneous natural mortalities determined by three independent methods based on life-history parameters were 0.35, 0.64 and 0.77. Seasonal total mortalities were calculated by the length converted catch curve method for evaluating seasonal exploitation ratios (E). The E-values exceeded 0.4, indicating overexploitation during almost all the seasons studied. This was supported by the large reduction in the total landings of S. commerson from 27 762 t in 1988 to 3265 t in 1993.

The study of fluctuation of large pelagic stock (yellowfin tuna, skipjack tuna, longtail tuna, Narrow-barred Spanish mackerel ) in order to optimum exploitation in the Persian Gulf & Oman sea This study was carried out from 2005-07 in order to acquire some biological characteristics and population dynamic parameters for stock management and responsible fisheries. Thunnus albacares (yellowfin tuna), katsuwonus pelamis (skipjack tuna), Thunnus tonggol (longtail tuna) and scomberomorus commerson (Narrow- barred Spanish mackerel) were sampled. In total, length frequency of 9345 specimens of yellowfin tuna were analyzed. Size range was 37-172 cm. Teleost fishes were the most dominant prey species observed in this study (42%), Occurrence of Potunus Pelagicus was found to be the second (28%).Sthenoteuthis oualaniensis (22%), Natosquilla (5%) and octopus (3%) also were identified in the gut content of the yellowfin tuna. Length of maturity (50%) of yellow fin tuna was estimated 77.2 cm and spawning season was started from May. 8443 specimens of skipjack with size range of 32-90 cm were sampled. 48% of food items were teleost fishes. Squid and shrimp were also identified. Spawning season was begun from June. Growth parameters & fishing mortalities of yellow fin tuna and skipjack tuna were also estimated. Size range if longtail tuna was from 26-125cm Length infinity was estimated 132.3 cm with growth parameter of 0.35 per year. In total 10451 specimens of narrow- barred Spanish mackerel were sampled. Size range was from 20-164 cm. Teleost fishes were the most dominant prey species observed in the study (91.3%). Crustaceans (0.6%) and Indian squid (0.2%) also were identified in the specimens. Length maturity (50%) was estimated 83.6cm.

R. Endean , J. K. Griffith , J. J. Robins , L. E. Llewellyn and S. A. Monks . Variation in the toxins present in ciguateric narrow-barred Spanish mackerel, Scomberomorus commersoni. Toxicon31, 723–732, 1993.—Water-soluble and lipid-soluble toxins present in six specimens of Scomberomorus commersoni captured in subtropical Queensland were compared with those detected in a specimen studied earlier. All specimens were from batches that had been involved in human poisonings. All specimens contained significant amounts of potent water-soluble toxins, the most important of which in terms of contribution to the lethal potency of fish flesh was unidentified toxic material which tested positively for alkaloids. All specimens contained lipid-soluble toxins including ciguatoxin-like and scaritoxin-like material, the latter usually predominating. Amounts of water-soluble toxins with lethal potencies ranging from 14.9 MU to 115 MU/100 g of flesh and of lipid-soluble toxins with lethal potencies ranging from 8.8 MU to 39.9 MU/100 g of flesh were found. (A mouse unit, MU, is the minimum amount of toxic material expressed in g required to kill a 20 g mouse within 24 hr following i.p. injection.) The lethal potency of water-soluble toxins per g of fish exceeded that of lipid-soluble toxins per g of fish for five of the seven specimens of S. commersoni now investigated. Based on a lethal dose to humans of 2500 MU all fishes contained lethal amounts of toxic material. The relative amounts of water-soluble and lipid-soluble toxins present in the flesh of a specimen of S. commersoni were altered by different cooking procedures.

Growth data for Scomberomorus commerson in Oman were coupled with other information about the fishery to provide preliminary management recommendations. Length data collected from the commercial catch were used in conjunction with counts of daily and annular growth marks on otoliths to determine growth rate. These data revealed that S. commerson grow very rapidly, reaching a size of about 80 cm in 1 year and between 100 and 110 cm in 2 years, after which growth slows considerably. A tabular yield model indicates that protection of rapidly growing young S. commerson could have significant benefits for the fishery. This protection could be accomplished by instituting moderate mesh regulations.

Narrow-barred Spanish mackerel (Scomberomorus spp.) is a species of fish that is widely preferred due to its high potential and economical value. This research is aimed to utilize seaweed (Eucheuma cottonii and Eucheuma spinosum) to increase iodine and dietary fiber content of fish meatballs to help fulfill the daily needs of Indonesians. The first stage of this research was conducted to determine the best type and concentration of seaweed flour to be added to the fish meatballs dough. A series of seaweed flour addition concentration employed in this research are 1, 2, 3, 4, and 5% for each type of seaweed separately. Several factors put into consideration when selecting the best seaweed addition concentration were moisture content, texture, and organoleptic tests (scoring and hedonic). Through moisture content, gel strength, and organoleptic analysis, 2% Eucheuma cottonii was chosen to be added. Second stage of this research was conducted to compare the chosen meatball with control. The chosen fish meatball has better profile of moisture, fat, ash, carbohydrate, dietary fiber, and iodine content compared to control. Dietary fiber and iodine content analysis showed that the chosen fish meatball contain 0.0046% dietary fiber and 102 mcg/100g iodine. Keywords: Narrow-barred Spanish mackerel, Eucheuma cottonii, Eucheuma spinosum, iodine content, dietary fiber

The growth of narrow-barred Spanish mackerel (Scomberomorus commerson) was examined over a broad spatial scale encompassing the east coast of Queensland, Australia. Our aim was to use back-calculation to identify potential biases in growth estimation, and to provide a more recent estimate of growth for Spanish mackerel on the east coast of Queensland. Growth trends were determined using the body proportional hypothesis (BPH) back-calculation model and compared between back-calculated and observed length-at-age data. The back-calculated von Bertalanffy growth function parameters estimated for males and females, respectively, were L∞ = 1047 mm, K = 0.75, t0 = –0.18 and L∞ = 1248 mm, K = 0.51 and t0 = –0.39. Significant differences in growth of Spanish mackerel sampled among different regions along the east coast were observed. A comparison of back-calculated and observed length-at-age data revealed significant biases in the observed length-at-age data for younger aged fish. Our findings contrast with previous estimates of growth for Spanish mackerel from the east coast of Queensland and highlight the use of back-calculation for the first few annuli as a means of avoiding biases in growth estimation arising from gear selectivity associated with fishery-dependent samples of fast-growing fish.

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.

The following fish from the Australian east coast belonging to the family Scombridae were examined for monogenean gill parasites: 29 Scomberomorus commersoni, 3 S. queenslandicus, 1 Sawara niphonius, 2 Grammatorcynus bicarinatus, 6 Cybiosarda elegans. Gotocotyla bivaginalis, G. secunda, Pricea multae, Pseudothoracocotyla indica comb. nov. and P. gigantica sp. nov. are described, and their distribution on the gills, as well as that of some parasitic copepods, is discussed. It is concluded that the restriction of habitats on the gills is not due to interspecific competition or reinforcement of reproductive barriers, but to the increased probability of intraspecific contact and thus mating. Four of the five monogenean species recorded from mackerel on the Australian east coast have also been found in the South China Sea and the Indian Ocean.