The feeding habits of skipjack tuna Katsuwonus pelamis juveniles (8.5-66.8 mm standard length) were examined, collected from the tropical western Pacific in October to December 1994, and their habits were compared with those of the other tuna Thunnus spp. juveniles (9.8-55.3 mm standard length). The indices, frequency of occurrence of each food item in the total number of stomachs examined (%F), percentage of number of each food item to the total number of all food items identified (%N), percentage of wet weight of each food item to the total wet weight of all food items identified (%W), and relative importance of each food item (IRI) were estimated in the north equatorial current (NEC) and the north equatorial countercurrent (NECC) areas. The most dominant prey item of skipjack juveniles in the two areas was fish larvae. Other major prey items in the NEC area were Euphausiacea, Amphipoda, and Copepoda; whereas those in the NECC area were Copepoda, Cephalopoda, Euphausiacea, and Amphipoda. In the other tuna juveniles, the IRI of fish larvae in the two areas was remarkably high. Other prey, Euphausiacea and Cephalopoda in the NEC area only and Cephalopoda in the NECC area, were also found. These results indicate that the skipjack juvenile is primarily a piscivorous feeder although they also depend on various other prey organisms, whereas the other tuna juveniles are stronger piscivorous feeders.

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Early growth, yolk and oil globule absorption, early morphological development and initial feeding were studied in the Black Sea turbot Psetta maxima. Based on energy transition and morphological development, the nutritional transition process from endogenous to exogenous sources was divided into six phases: (i) primordial phase (from hatching to ≈ 30 h after hatching, HAH); (ii) organogenesis phase (to ≈ 90 HAH); (iii) onset of feeding (to ≈ 110 HAH); (iv) early feeding (to ≈ 190 HAH); (v) intensified feeding (to ≈ 230 HAH); and (vi) completion of oil globule absorption (to beyond 345 HAH). Based on comparisons with early life stage features of other marine species, the turbot larvae were shown to possess the following characteristics: (i) oil globule remaining for a long period, resulting in an extended mixed feeding period; and (ii) feeding rate extremely high in larvae immediately following final absorption of the oil globule. These features in early turbot larvae were regarded as advantageous for survival in a rearing condition, although the coincidence of initial feeding with completion of yolk absorption signaled a period of leveled-off growth rate.

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The mechanisms by which catch yields of the manila clam Ruditapes philippinarum have decreased drastically in Kumamoto Prefecture, southern Japan, and the larval recruitment by which benthic populations of the clam are maintained were studied. Samples at different growth stages (planktonic larvae, new settlers, and small to large bivalves of the species) were collected from February 1997 to December 1998 on two tidal flats (Kawaguchi and Nameishi, 20 km distance from each other) along the eastern coast of Ariake Sound. Densities of planktonic larvae, new settlers and small bivalves were generally higher at Kawaguchi than Nameishi. The higher density of large bivalves at Kawaguchi depends on a high larval density. Larval retention mechanisms coupled with water movement at Kawaguchi, such as tidal residual currents, may be related intimately with the higher larval density at Kawaguchi. Predation by shore birds at and after recruitment may be related to the lower density of large bivalves recorded at Kawaguchi in 1998, despite larval densities being higher there.

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A feeding trial was conducted to estimate the minimal dietary potassium (K) requirement for juvenile grass shrimp Penaeus monodon. Purified diets with seven levels (0, 0.3, 0.6, 0.9, 1.2, 1.5, 2.0 g/100 g) of supplemental potassium were fed to P. monodon (mean initial weight 0.75 ± 0.01 g) for 8 weeks. Each diet was fed to three replicate groups of shrimp. The rearing water contained 360 mg/L potassium. Weight gain and protein efficiency ratio (PER) of shrimp improved as dietary potassium supplementation level increased up to 1.5 g K/100 g diet and thereafter declined significantly (P < 0.05). Feed efficiency (FE) of shrimp also showed a similar trend. However, whole body K concentration of the shrimp kept an increasing trend up to 2.0 g K/100 g diet. Analysis of the weight gain (percent) and PER of the shrimp by polynomial regression indicate that the minimal dietary potassium requirement in growing P. monodon is approximately 1.2 g/100 g.

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The radula morphology of Haliotis discus hannai was examined by scanning electron microscope from the larval to the adult stage. The radula of competent larvae contained 11-13 transverse rows of teeth after 6-7 days at 20°C. The number of rows increased to 25-30 during the first several days after settlement, but then remained approximately constant throughout the post-larval period, increasing again in abalone larger than 4 mm in shell length (SL). In post-larvae <-1 mm SL, only two pairs of lateral teeth (L1, L2) were present in the larval radula. An additional three pairs of lateral teeth (L3-L5) were added progressively as post-larvae grew from 0.9 mm to 1.9 mm SL. Marginal teeth were added steadily from one pair in larvae to 30-40 pairs at 3-4 mm SL, 70-80 pairs in 30-40 mm juveniles, and 70-90 pairs in 90-100 mm adults. The serrations on the working edges of the rachidian (R) and lateral teeth became less pronounced as the abalone grew. Nearly all serrations disappeared from the rachidian (R) and inner lateral teeth (L1, L2) by -2 mm SL, and from the outer lateral teeth (L3-L5) by 20 mm SL. For abalone larger than 1.5 mm SL, the L3-L5 teeth became longer and more pointed, which increased the space between adjacent rows of teeth. Post-larvae <1 mm SL had highly curved teeth with clearance angles of approximately or less than zero, whereas larger abalone had positive clearance angles. These radula developments appear to be related to transitions in feeding habits from microbial to macroalgal diets.

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The present study was conducted to investigate the effects of dietary vitamin A on reproduction and egg quality in Japanese flounder Paralichthys olivaceus. Broodstock were fed experimental pellets containing two levels of vitamin A [11×10³ IU/100 g (control diet; CD), 337 × 10³ IU/100 g (experimental diet; ED)] for approximately 2 months before spawning and during the spawning period. Two groups of five females (average weight 1.4 kg) and 10 males (average weight 0.7 kg) were randomly allocated to two 30 m³ indoor tanks. Total egg production of the CD group was slightly higher than the ED group. Percentage of buoyant eggs and hatching rate of the ED group were significantly higher than the CD. In other egg quality parameters, such as percentage abnormal larvae and starvation tolerance of larvae, no notable difference was found between these two groups. At the end of the experiment, the skin color of broodstock in the ED group was darker than that of the CD group. Vitamin A content in eggs of the ED group was significantly higher than that of the CD group. However, the difference in vitamin A content in eggs between the ED and CD groups was much smaller than that in the liver of the females between the two groups. These results indicate that feeding broodstock a higher level of vitamin A increases the vitamin A content in eggs but does not affect egg quality in Japanese flounder because excess dietary vitamin A was stored mainly in the broodstocks' liver.

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Postprandial changes of free amino acid (FAA) concentrations in plasma and feed digesta contents were examined in yellowtail, Seriola quinqueradiata (220-280 g bodyweight) fed non-fishmeal diets either with or without supplemental crystalline amino acids (lysine, methionine, threonine, and tryptophan) in order to evaluate the availability of supplemental amino acids. Non-fishmeal diets containing 30% soy protein concentrate as the major protein source were prepared in three diet forms: soft dry pellet, extruded pellet, and single moist pellet. The level of plasma FAA and feed digesta content were determined at 0, 3, 6, 9, 12, 18, and 24 h after feeding. Plasma levels of four supplemental amino acids in fish fed the non-fishmeal diets with EAA were higher than those of fish fed diets without EAA, suggesting that yellowtail can efficiently absorb supplemental crystalline amino acids irrespective of diet form. However, a remarkable difference was observed in the periodical patterns of these four amino acids between FAA derived from supplements and those from feed protein. Moreover, FAA patterns in fish fed the non-fishmeal diets with EAA were different from those of the control fishmeal diet. Of note, methionine concentration was markedly high during the whole experimental period, resulting in an amino acid imbalance that may have caused lower feed performances in fish fed the non-fishmeal diets with EAA compared to the control fishmeal diet.

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Fish cage farming generates large amounts of organic waste in the form of unconsumed feed and fecal matter, resulting in sediment deterioration and a threat to its own sustainability. Field studies analysed the scale of the impact of fish cage farming on sediment quality, variability of impact and spread of sediment enrichment in the vicinity of a fish farm. Two fish culture sites near the Fukuyama area of the Seto Inland Sea of Japan were chosen for the study. There was a significant difference between the quality of the sediment in aquaculture and non-aquaculture areas. The sediment underlying the fish cage farms was found to be extremely reducing, acidic and sulfidic. Sediment ignition loss did not vary markedly with the season. However, the redox potential and acid volatile sulfide content of aquaculture areas did show some seasonal variation. Sediment encircling a 165 m radius from the center of a farm in Yokota was judged as organically enriched by fish farming. A variation in sediment quality within the two sites and also within the stations was observed. Based on sediment quality, the stations could be categorized as less affected, highly affected or moderately affected.

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The age distribution of the sea urchin Strongylocentrotus nudus in relation to algal zonation was studied in a sublittoral rocky area on Oshika Peninsula, northern Japan, from June 1995 through to August 1996. The algal zonation observed there extends from a shallow area of cobbles to deeper areas dominated successively by Sargassum yezoense, Eisenia bicyclis and, finally, crustose coralline red algae. One-year-old sea urchins occurred only on the cobbles and crustose corallines in contrast to the presence of 2-year-old individuals from all areas and the restricted distribution of individuals aged 3 years and over to Eisenia and crustose corallines. Calculated mean body sizes in the Eisenia area became larger after the age of 2 years compared with those in the area of crustose corallines. Spawning was ascertained histologically in both the Eisenia and crustose coralline areas, although gonad indices were higher in the former area than in the latter throughout the year. Gut contents were dominated by E. bicyclis in the Eisenia area, and by crustose coralline red algae and small algae in the crustose coralline area. Thus, the sea urchin may settle most abundantly on crustose corallines and lives there for 1-2 years. Thereafter, they expand their habitat toward the Eisenia area, where there is richer sources of food for attaining a higher growth rate and to generate heavier gonads.

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The feeding habits of the serranid fish Cephalopholis urodeta were examined on the basis of 204 adult specimens collected from coral reef areas at Iriomote Island, Ryukyu Islands, Japan. Sampling was conducted in November 1997 and February, May, and August 1998. Among the specimens, 95 (46.6%) had empty stomachs, the mean Stomach Fullness Index of the specimens overall being extremely low (0.6). Over a 1-year period, the most important prey of this species were small fishes and decapod crustaceans, the two categories together constituting 73.4% of stomach contents by weight. However, seasonal differences in basic dietary composition were apparent. Fishes were abundant in the diet in May and November, whereas the proportion of hermit crabs in the diet was higher in February compared to other months.

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A maximum likelihood method of estimating gillnet selectivity when data are obtained by gillnet fleets consisting of several nets of differing mesh size is presented in this paper. The SELECT model is expanded by application of the relative length (i.e. the ratio of fish length to mesh size) to obtain a master curve of gillnet selectivity. Four kinds of functional model, normal, lognormal, skew-normal and bi-normal are fitted to the data. In addition, two cases in which the relative fishing intensity is either estimated or fixed by catch effort are compared. The bi-normal model has the lower model deviance regardless of whether the relative fishing intensity is estimated or not. The estimation of relative fishing intensity by catch effort is also examined in which the estimates of the parameter of the SELECT model are compared with the catch effort as determined by the number of nets of each mesh size used. For the bi-normal model these quantities compare well. Thus, it is concluded that this method gives reliable estimates even if data for each mesh size is obtained with different catch efforts.

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A feeding trial was conducted to estimate the dietary folic acid requirement of juvenile tilapia, Oreochromis niloticus×O. aureus. Purified basal diets with eight levels (0.0, 0.3, 0.6, 1.0, 3.0, 6.0, 10.0, 20.0 mg/kg diet) of supplemental folic acid were fed to tilapia (mean initial weight 0.41±0.01 g) for 8 weeks. Each diet was fed to three replicate groups of fish reared in a closed recirculating system. Results indicated that weight gain and feed efficiency (FE) were significantly (P<0.05) greater in fish fed ≥1.0 mg folic acid/kg diet than fish fed 0.3 mg folic acid/kg diet or the unsupplemented control diet. Mortality of fish was not affected by dietary treatment. Hepatic folic acid concentration increased with an increase in dietary folic acid and values were significantly higher in fish fed ≥6.0 mg folic acid/kg diet than fish fed the control diet. An analysis of the weight gain percentage by broken-line regression indicates that the adequate dietary folic acid requirement in juvenile tilapia is 0.82 mg/kg diet.

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The effect of reward level (amount of food received in response to one trigger actuation) on the self-feeding activity of juvenile yellowtails was examined. Three groups of 10 juvenile yellowtails (mean bodyweight, 65.6 g) were allocated randomly to three 200 L cylindrical tanks set in the experiment room. Each tank was illuminated by overhead fluorescent lamps with a light : dark photoperiod regimen of 12 h : 12 h (light 06.00-18.00 hours). A rod-type tactile switch was used to activate the self-feeding device. Three levels of reward were set up by installing a different number of identical feeders for each group: one feeder for the low-reward group, three feeders for the medium-reward group and five feeders for the high-reward group. Each feeder delivered 3-7 pellets per actuation. Yellowtails in all groups showed a clearly diurnal feeding pattern that was synchronized to the given photoperiod. Average number of feeder actuations per day was highest (219/day) in the low-reward group. Second highest was the medium-reward group (116/day), and last was the high-reward group (67/day). The resultant average feed intake per day was 27.1 g/day in the low-reward group, 31.5 g/day in the medium-reward group and 28.4 g/day in the high-reward group. Thus, yellowtails appear to have the ability to regulate the amount of feed delivered daily by increasing the number of food demands when the reward is low and decreasing the number of food demands when the reward is high.

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This study was conducted to investigate the effect of squid meal and astaxanthin in dry pellets on the spawning performance of striped jack. Two groups of 8-year-old fish with an average bodyweight of 3.5±0.4 kg were used. The control group was fed a raw fish mix (RF) and the experimental group was fed steam dry pellets (as-DP) containing 10 p.p.m. astaxanthin and squid meal, the latter replacing half the fish meal. Each group was fed once a day, three times a week in floating net cages for a period of 5 months. Seven females and seven males were selected from each group and transferred to 65 m³ indoor concrete tanks for spawning, where they were kept at optimum spawning conditions (22°C) for 1 month. The average bodyweights of selected fish were 3.8±0.5 kg and 3.8±0.6 kg for the RF and as-DP groups, respectively. Both groups spawned a total of 18 times and the mean total egg production and egg quality, measured in terms of buoyancy, fertilization and hatching rates, showed no significant differences (P>0.05) between groups. Total larval production was 679.9×10³ and 678.1×10³ larvae/kg-female for the RF and as-DP groups, respectively. These results show that the combination of astaxanthin and squid meal in dry pellets for striped jack broodstock improved the overall spawning performance to a level similar to that of fish fed on RF.

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Twenty-seven fish species from the Sakishima Islands and Nagasaki living in water temperatures of 28°C (12 fish species) and 17°C (15 fish species), respectively, were used as sample fishes. Postmortem temporal changes of K-values were measured at 1-h intervals in the dorsal ordinary muscle of each fish, of which the remaining body was then kept in water at a controlled temperature of 32°C. The increasing rate of K-value at 32°C (ΔK₃₂) was calculated from the regression line formed from the relationship between the kept time and the K-value. Muscle fiber types were differentiated by the stability of actomyosin ATPase preincubated in either acid or alkaline conditions. ΔK₃₂ varied widely according to fish species, ranging from 0.98%/h to 14.00%/h. Although the mean value of each body of water was somewhat higher for fishes from Nagasaki at 17°C than in fishes from Sakishima Islands at 28°C, the difference was not significant. The interposition percentage of pink muscle fibers into the dorsal ordinary muscle was also distributed widely, ranging from 0% to 56.53% in number and from 0% to 53.68% in area. A significant correlation was recognized in the relationship between the number or area percentage of pink muscle fibers and deviation percentage of ΔK₃₂ for all fish species sampled; r=0.411 (P<0.05) for number percentage and r=0.518 (P<0.01) for area percentage. These results suggest that the interposition of pink muscle fibers into the dorsal ordinary muscle might accelerate a temporal change of K-value in fish.

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The present study compared and examined the characteristics of actomyosin among white (W), pink (P), and red (R) muscle fiber types in carp (cultured). Both the superprecipitation reaction and the Mg²⁺-ATPase activity of actomyosin became higher with increased Ca²⁺ concentration (pCa 7.0-pCa 5.0) and with decreased adenosine triphosphate (ATP) concentration (3.0-0.5 mM) in all three muscle fiber types. A comparison of the three fiber types shows that the superprecipitation reaction of actomysoin was lower in the order of W<P<R and, in contrast, was higher for Mg²⁺-ATPase activity in the order of W>P>R. A significantly positive correlation between both values was found for each of the three muscle fiber types, but these correlations were clearly different among the three muscle fiber types, and the superprecipitation reaction of actomyosin was lower in the order of W<P<R when Mg²⁺-ATPase activity was at the same level. In conclusion, the characteristics of actomyosin were remarkably different among white, pink, and red muscle fiber types.

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Fouling organisms cause serious problems by settling on ships' hulls, and other marine infrastructures. Organotin compounds have been developed as effective antifoulants. However, environmental problems are associated with these compounds. It is necessary to find antifouling substances that exhibit a lower toxicity than those substances currently used. A new pyrimidine derivative, 3, 4, 5, 6-tetrahydro-6-hydroxymethyl-3, 6-dimethyl-4-pyrimidinecarboxylic acid, (compound 1) and zooanemonin (compound 2) were isolated from the marine sponge Protophlitaspongia aga as antifouling substances against the barnacle Balanus amphitrite. We also found that α-nicotinamide ribose (compound 3) inhibited germination and the attachment of Ulva spores.

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To investigate the reducing ability of met-myoglobin (metMb) reductase, browned tuna meat was immersed with/without metMb reductase (0.103 unit/mL) for 120 min at 4°C. The metMb reductase activity of browned tuna meat significantly increased, whereas no significant change was observed in the control sample for the first 10 min of immersion (P>0.05). After comparing the changes in metMb reductase activity, metMb content, Hunter's ‘a’ and color, it was observed that the reductase did recover the bright red color. To further confirm the role of metMb reductase in color stability, fresh tuna meat was first immersed in metMb reductase (0.503 unit/mL) or a mixture of reductase and nicotinamide adenine dinucleotide (NADH) (1 mM) solutions at 5°C for 10 min, and then stored at 4°C and relative humidity 100%. No significant changes in metMb accumulation and in metMb reductase activity were observed between samples treated with enzyme alone and enzyme+NADPH (P>0.05). Changes in metMb reductase activity, metMb, Hunter's ‘a’ value and color for both the control and treated samples suggested that immersion in metMb reductase could extend the color stability of tuna meat, and that the enzymatic reduction of metMb by its reductase occurred during refrigerated storage.

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The amino acid sequence of a D-galactose-binding lectin isolated from the hemolymph of the acorn barnacle Balanus rostratus was determined. The lectin (BRL) (M_r 120K) is a multimeric protein whose subunit consists of 182 amino acids. The amino acid sequence was compared with those of multiple lectins (BRA-2, BRA-3) from Megabalanus rosa to explore the relationship between the structures and the inhibitory activity toward the crystal growth of calcium carbonate. Although BRL was 46% identical to BRA-2 and 15% identical to BRA-3, the lectin had no inhibitory activity, unlike BRA-2 and BRA-3. Both the number and the localization of acidic amino acid residues and their amide forms were different among them. Observations by scanning electron microscopy revealed modifications in the size and morphology of the calcium carbonate crystals grown in the presence of the lectins.

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To clarify the contribution of polymerization of myosin heavy chain (MHC) by disulfide bonding to increased gel strength of cooked gel via preheating, the pastes of walleye pollack surimi (SS and C grades) were preheated at 25°C and 40°C for a variety of hours prior to heating at 80°C for 20 min. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns of cooked gels were analyzed with and without reducing the samples, which were solubilized in 8 M urea-2% SDS solution. The formation of polymers by disulfide bonding in cooked gels was almost constant in each of the SS and C grade surimi gels despite the period of preheating. Therefore, it was suggested that polymerization by disulfide bonding occurred during cooking at 80°C and not during preheating.

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To confirm the contribution of polymerization and degradation of myosin heavy chain (MHC) during preheating to the gel-forming ability of fish meat paste, walleye pollack surimi paste was preheated at 30°C and 50°C prior to heating at 80°C in the presence of various inhibitors. At 30°C, ethyleneglycol bis(2-aminoethyl ether)-N, N, N', N'-tetraacetic acid (EGTA) and ethylenediaminetetraacitic acid (EDTA) inhibited gel formation as well as the polymerization of MHC, whereas dithiothreitol (DTT) and leupeptin promoted gel formation, which was accompanied by the enhancement of MHC polymerization and decreased MHC degradation, respectively. At 50°C, leupeptin inhibited MHC degradation and improved gel strength, whereas EGTA, EDTA and DTT had no effect on MHC polymerization and degradation and did not affect gel formation. The results demonstrate that the gel strength of cooked gel (80°C) is not affected by preheating at 30°C and 50°C and does not inhibit polymerization and degradation. Results suggest that the gel strength of cooked gel is dependent on the polymerization and degradation of MHC during preheating.

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A facile synthesis of Tyrian purple, a valuable purple dye derived from gastropod mollusks in ancient times, has been accomplished. Tyrian purple, 6, 6'-dibromoindigo, was easily obtained by three steps of reactions from the commercially available 6-bromoindole, on the basis of a biosynthetic pathway of indigo and biological precursors of the purple. Iodination of 6-bromoindole, followed by acetoxylation with silver acetate in acetic acid, afforded 6-bromo-3-acetoxyindole, whose alkaline hydrolysis accompanying air oxidation produced Tyrian purple.

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This study attempted to reduce the lipid and water contents in boiled skipjack loins by vacuum treatment and the quality of vacuumed boiled meat was then evaluated during the chilled and frozen storage. The boiled meats were vacuumed at a pressure of 400 Pa for 30 min using a vacuum freeze dryer as an experimental convenience in order to degrease, cool and dehydrate rapidly. The vacuumed boiled meats were stored at 0.0±0.2°C for 10 days and at -20±0.5°C for 90 days. The unvacuumed boiled meats were cooled by air-cooling and stored as the control. Lipid content on a wet basis (w. b.) was reduced as much as 0.5% in the ventral part and 0.4% in the dorsal part of the boiled meats after vacuum treatment. Water content (w. b.) was reduced as much as 2.5% in the ventral part and 3.0% in the dorsal part. The thiobarbituric acid and volatile basic nitrogen values in vacuumed boiled meats were significantly lower (P<0.05) than that in unvacuumed boiled meats during storage. Inosine monophosphate (IMP) was only detected as a major nucleotide (about 70%) in boiled meats, and the decomposition of IMP in vacuumed boiled meats was smaller than that in unvacuumed boiled meats during storage. It was concluded that the quality of boiled skipjack loins could be improved by vacuum treatment as a preprocessing procedure in the production of dried skipjack such as katsuobushi.

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Oxidative stability of lipids from squid tissues was compared with those of other marine lipids. On the basis of peroxide formation, total lipids (TL) from squid viscera or squid muscle with skin were most oxidatively stable, followed by squid eye TL, trout egg TL, bonito oil, and tuna orbital TL, respectively. This tendency in oxidative stabilities was also confirmed by the decrease in unoxidized polyunsaturated fatty acids during oxidation. Analyses of tocopherol contents and lipid compositions suggested that the higher oxidative stabilities of three kinds of squid tissue TL and trout egg TL compared to those of bonito oil and tuna orbital TL would be mainly because of the presence of phospholipids (PL) in squid tissue lipids and trout egg TL. However, the oxidative stability of lipids containing PL did not always decrease with increasing PL contents and stability was strongly influenced by PL composition. As squid viscera contained more than 25% of TL and these lipids were oxidatively stable, squid viscera may be used as a good resource of functional lipids rich in eicosapentaenoic acid and docosahexaenoic acid.

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Chub mackerel (34-35 cm, approximately 500 g), which were caught by fishing with a rod and line at the Bungo Channel, Oita prefecture, were rested overnight in a fish preserve and either killed by decapitation (control group) or allowed to struggle in air for 30 min (struggled group). Muscle samples were excised every 4 h, and measurements on breaking strength and histological observations were done for both groups. The breaking strength of muscle in the control group was significantly higher than that in the struggled group, whereby a decrease in breaking strength was delayed for 12 h compared to the struggled group. Light microscopy showed space extension among muscle cells in association with a decrease in breaking strength. Especially in the struggled group, the extended area was larger and the difference in area was significant at the time when breaking strength showed a significant difference. Using electron microscopy, the extended area showed cut and/or disappeared collagen fibrils. From these results, it was demonstrated that struggling to death promoted the degradation of collagen fibrils and the weakening of connective tissue and, resultantly, led to the faster softening of muscle of chub mackerel.

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