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Effects of phenolic compounds in conjunction with L-cysteine/ l -ascorbic acid on the redox state of myoglobin (Mb) and their efficacy to maintain the color and quality of refrigerated longtail tuna (Thunnus tonggol) slices were investigated. Purified metmyoglobin (metMb) and oxymyoglobin (oxyMb) samples were added with epigallocatechin-3-gallate (EGCG) or quercetin individually or in combination with L-cysteine (CT) or L-ascorbic acid (AA) at 4 °C. EGCG in combination with AA (EGCG+AA) and AA alone significantly reduced metMb and increased oxyMb levels (p < 0.05). Furthermore, the slices of tuna were treated with EGCG+AA (200 and 200 mg/kg, respectively) exhibited superior color retention (high a* value and a*/b*) and reduced lipid and protein oxidation more potentially, compared to other treated slices. AA alone was less effective in preserving color and quality of slices. Therefore, EGCG+AA effectively maintained the color and quality of tuna slices stored at 4 °C. [Display omitted] • Metmyoglobin and oxymyoglobin were isolated from longtail tuna dark muscle. • EGCG or Quercetin was used along with reducing agents (L-cysteine/ l -ascorbic acid). • EGCG combined with AA (EGCG+AA) and AA alone reduced metMb effectively. • EGCG+AA retained red color and quality of slices than other treatments. [ABSTRACT FROM AUTHOR]

Longtail tuna ( Thunnus tonggol) is one of the most economically important tuna species in Iranian waters of Persian Gulf and Oman Sea. Some population dynamics parameters of this species were investigated in coastal waters of the northern Persian Gulf and Oman Sea from January to December 2014. The fork length (FL) of all specimens ranged from 27 to 107 cm, and total weight (TW) was between 200 and 12,000 g. Among the length frequencies examined, specimens with fork length in the range of 62-65 cm were the dominant group. The equation of length-weight relationship was estimated as TW = 0.00003 × FL ( R = 0.84) and isometric growth model was determined for longtail tuna in study area. The parameters of Von Bertalanffy growth function were obtained as: L = 111.23 cm, k = 0.3 year and t = −0.38 years and ϕ′ = 3.6. The annual instantaneous rate of total mortality ( Z), natural mortality ( M) and fishing mortality ( F) was estimated to be 1.15, 0.43 and 0.72 year, respectively. The exploitation rate ( E) was calculated as 0.63 indicating that longtail tuna was fully exploited in the study region. [ABSTRACT FROM AUTHOR]

The study was conducted to detect histidine decarboxylase-producing bacteria and determine histamine content for evaluation of potential histamine poisoning in 30 frozen specimens of longtail tuna harvested from the Oman Sea. Bacteriological isolates and the amount of histamine were obtained from 500 g of gill muscles. Trypticase soy agar was used for examination of mesophilic and psychrophilic counts. Enterobacteriaceae and histamine producing bacteria were enumerated in violet red bile dextrose agar and Niven's media, respectively. The results indicated that the average of total count and psychrophilic count were 4.81±0.26 and 4.66±0.25 Log10 CFU/g, respectively. Several bacteria were identified as histidine decarboxylase-producing bacteria. Among them, Clostridium perfringens had the highest contribution (24.4%) followed by Proteus spp. (23.0%), Klebsiella spp. (13.9%) and Enterobacter spp. (11.1%). Histamine contents in 20.0, 15.0 and 65.0% of samples were <20, 20-50, and >50 ppm, respectively. The high percentage of samples (65%) with histamine content higher than the standard (<50 ppm) suggests potential histamine poisoning due to longtail tuna fish consumption in humans. [ABSTRACT FROM AUTHOR]

Longtail tunaThunnus tonggolis a neritic species of the family Scombridae, having a confined coastal distribution to tropical and temperate waters of the Indo-Pacific region. In the present study, the population structure of longtail tuna was examined using sequence analysis of the mtDNA control region from two geographically distinct locations along the northwest coast of India. A 500 bp segment of the D-loop region was sequenced and analysed for 98 longtail tuna individuals. Analysis of population differentiation showed no significant genetic differentiation between the two sampling localities (ΦST= 0.005,P= 0.200). Results were further corroborated by a non-significant nearest-neighbour statistic (Snn= 0.489,P= 0.549). Phylogeographic analysis revealed two haplogroups, but there was no obvious phylogeographic pattern separating the samples of the two localities. The present study suggests a single panmictic population of longtail tuna in the northwest coastal waters of India. [ABSTRACT FROM PUBLISHER]

Advances in fishing technologies have increased the efficiency and diversification of recreational fisheries. This poses challenges for surveying specialised or 'hard-to-reach' recreational fishers (e.g. sport fishers) that may take the majority of the recreational catch for some species, but are too rare within the general population to be sampled cost-effectively using existing methods. We trialled two new methods-time-location sampling (TLS) and online diaries-for surveying specialised recreational longtail tuna ( Thunnus tonggol) fishers. Results were compared with a concurrent traditional access point survey (APS). Online diaries were inexpensive but unsuitable for collecting representative data due to avidity, volunteerism, and differential recruitment bias. APS yielded high resolution data on catch, effort and size composition but was expensive and ineffective for sampling all components of the fishery. In contrast, TLS conducted at fishing tackle stores was cost-effective for accessing the breadth of fisher types due to the need for all fishers to purchase or to inspect fishing-related products at some point. Given the frequent absence of complete list frames for recreational fisheries, we suggest undertaking multiple TLS surveys to collect catch rate data and to simultaneously estimate population size using capture-recapture approaches in order to estimate the total recreational catch of species of interest. [ABSTRACT FROM AUTHOR]

Abstract: A specialised recreational land-based game fish fishery in south-eastern Australia was characterised using electronic fisher diaries. Live bait and lure-casting were the primary methods used during long trip durations (mean 9.44±SD 6.65h). Effort was temporally and spatially dynamic, whereby fishers appeared to follow the 20°C sea surface temperature isotherm. A total of 4436 fish from 44 taxa was recorded. The highest mean catch rates were recorded for Seriola lalandi, Thunnus tonggol, and Istiompax indica (0.0025–0.0224fishh−1). However, at least 42% of trips were unsuccessful in capturing nominated target species. High average expenditure of $1734.75 (±788.07) per fisher yr−1 was attributed to long travel distances to fishing locations and specialised equipment. The study highlighted the need to develop cost-effective survey methods to access a representative sample of ‘hard-to-reach’ fishers from specialised recreational fisheries. [Copyright &y& Elsevier]

Effectiveness of ethanolic galangal extract as an antioxidant in fish mince and fillet was investigated. The extract (5.8 μ gallic acid equivalent; GAE) reduced deoxygenation of sea bass haemoglobin ( Lates calcarifer) at pH 6.5. The lag time for TBARs development in washed sea bass mince mediated by the haemoglobin at pH 6.5 was extended from 2 to 8 days by added galangal extract (0.02% w/w GAE). Washing the sea bass fillet with low preformed lipid hydroperoxide (LHP) content by galangal extract solution (0.2% w/v GAE) effectively inhibited the TBARs formation throughout the storage. However, in the longtail tuna fillet ( Thunnus tonggol) having a significant content of preformed LHP, there was nonsignificant difference in the reaction lag time of the samples washed with the solution and with water. Thus, galangal extract can be used as an antioxidant in fish if its application is performed before initiation of lipid oxidation. [ABSTRACT FROM AUTHOR]

Deals with the study that attempted to process small tuna into ara-bushi. Number of longtail tuna used in the study; Determination of moisture content; Comparison of the chemical compositions of the raw meats and the product.