scispace - formally typeset
SciSpace - Your AI assistant to discover and understand research papers | Product Hunt

Journal ArticleDOI

Harvesting procedures, welfare and shelf life of ungutted and gutted shortfin pompano (Trachinotus falcatus) stored in ice

01 Jan 2019-Aquaculture (Elsevier Ltd)-Vol. 498, pp 236-245

TL;DR: The asset of using AQUI-S™ was possibly better fish welfare during the stunning and euthanising phase since exposure to ice-slurry was associated with escape swimming behaviour and slow death.

AbstractShortfin pompano (Trachinotus falcatus) were harvested from a floating cage culture. Handling stress (blood pH, white muscle pH, and rigor mortis) and welfare (“eye roll”) were determined for two harvesting methods: (i) batch netting and transfer to ice-slurry where the fish were killed and chilled (commercial method) and, (ii) transfer of fish to a tub immersed in the cage before it was lifted onto a barge where the fish were euthanised by an AQUI-S™ overdose. Half of the ice-slurry fish were gutted. All fish were subsequently stored for 18 d in ice for assessment of freshness (total bacterial counts, TBC and Quality Index Method, QIM) as well as skin and eye color. A modified QIM scheme for European sea bass was used with demerit points ranging from 0 to 18. Due to excessive swimming during crowding, both ice-slurry and AQUI-S™ fish were harvested in an exhausted condition. Upon sampling, none of the fish exhibited “eye roll”, indicating they were either unconscious or dead. Since the ice-slurry fish were not stunned immediately, the welfare of the fish might have been compromised. During rapid chilling, the fish developed cloudy eyes. The asset of using AQUI-S™ was possibly better fish welfare during the stunning and euthanising phase since exposure to ice-slurry was associated with escape swimming behaviour and slow death. Shortly after harvesting there were some significant differences between harvesting methods in terms of skin color. They were, however, largely offset by storage for one day. Only a few minor changes in skin color took place during further storage. Changes in eye color were more prominent than for skin. After storage for more than a week, the TBCs of gutted fish were significantly higher compared with ungutted fish (P

Topics: Aquaculture (52%), Pompano (51%)

Summary (3 min read)

1. Introduction

  • Since pompano are most commonly traded as whole fish in the market, the external appearance of the fish is also important.
  • In such a context, skin and eye color are relevant factors for the consumers perception of the product.
  • Hence, emphasis was also put on color assessment throughout storage.

2.1 Fish harvesting and ice storage

  • In case of both harvesting methods, vestibulo-ocular reflex, handling stress (blood pH and initial pH in white muscle), and body temperature were measured before the fish (n = 10) were subjected to analysis of skin and eye color.
  • The fish were gutted in the traditional local way, that is, by removing the gill arches along with intestines through the throat (without opening the belly).
  • Subsequently, the body cavities of gutted fish were thoroughly rinsed using bottled drinking water.
  • All fish were repacked in EPS flight boxes filled with crushed ice before transport to the Research Institute for Aquaculture No. 1 (RIA-1) in Hanoi (15 h transport) where the fish were subjected to chilled storage.
  • Melted ice was replenished with crushed ice and excess water was drained off daily.

2.2.2 pH in blood and muscle

  • A shielded glass electrode (SenTix 41, WTW, Wilhelm, Germany) connected to a portable pH meter (model WTW 330i WTW) was used for the determination of pH in blood and white muscle.
  • Just after sampling of fish from the AQUI-S TM bath or ice-slurry tub, gill arches were cut by using a scalpel before the pH electrode was brought in contact with the flowing blood to measure its acidity.
  • A similar pHelectrode was inserted directly in epaxial white muscle in front of the dorsal fin after an incision had been made by a scalpel.
  • The initial pH was recorded after some seconds when the fluctuating pH values had stabilized.
  • The initial pH describes peri-mortem anaerobic white muscle activity (e.g. escape behaviour).

2.2.4 Body and core temperatures

  • The body temperature of the fish was measured by using a Testo 110 thermometer (Testo AG, Lenzkirch, Germany) just after killing, between the dorsal fin and lateral line, next to the backbone in the thickest part of the fish.
  • Core temperatures during ice storage were measured similarly.

2.2.5 Quality Index Method

  • The authors chose to apply the QIM scheme intended for farmed sea bass (Dicentrarchus labrax) as shown in Seafish (2010) for their QI assessment of pompano.
  • The sea bass scheme ranges from 0 -22 demerit points and includes assessments of fillet color (0-2) and viscera (0-2).
  • Since pompano is normally traded as round fish, assessments of fillets and viscera were omitted.
  • Accordingly, the modified total QI score ranged from 0 (very fresh fish) to 18 (spoiled fish).
  • For gutted pompano, where gills and viscera were removed, the total attainable QI score became 11.

2.2.6 Mesophilic bacterial counts

  • On each sampling day, approximately 10 g of fish white muscle of three fish from each treatment was excised with sterile scalpels and forceps.
  • Before sampling, the skin around the sampling area was rinsed with 70 % ethanol.
  • The skin of the sampled cube was removed aseptically before the samples were mixed with 90 mL of 0.1% peptone water.
  • From the 10 -1 dilution, other decimal dilutions were prepared.
  • Total viable mesophilic bacterial counts were determined using plate count agar (PCA, Merck) after incubation for 24 h at 29 o C.

2.3 Statistical analysis

  • Initial pH and core temperature of ungutted and AQUI-S TM fish on Day 0 were compared by using Mann-Whitney U statistics since Shapiro-Wilk normality tests failed.
  • The effect of storage time (Day 1 to 18) on flesh pH, rigor status, core temperature, skin color, TBC and QI was tested using a one-way ANOVA followed by a Holm-Sidak post hoc test when significance was indicated.
  • Where normality tests or Levene Median tests of homogenity of variance failed, the Kruskal-Wallis One Way Analysis of Variance on Ranks method was applied followed by a Tukey post hoc test.
  • The relationship between the quality index (QI) and storage time was analysed by linear regression.
  • Unless otherwise stated, all data are presented as mean values ± standard error of mean (SEM).

3.1 Harvesting procedures and handling stress

  • Frenzied burst of activity (escape behaviour) occurred immediately once the crowding process started as well as during transfer to the ice-slurry tub.
  • After less than 5 min, practically all signs of movement had ceased.
  • The fish were subsequently lying sideways on the bottom of the tub exhibiting weak and sporadic ventilation movements.
  • No VORs altogether were observed for fish sampled from the ice-slurry tub as well as from the AQUI-S TM tub.
  • The effect of excessive peri-mortem swimming activity was measured as low initial pH values in white muscle, pH 6.55, similar for both treatments (Table 1 ).

3.2 Ice storage and market quality

  • Significant differences between the two treatments occurred on Days 10, 14 and 18.
  • If demerit points related to gills were omitted from the ungutted and AQUI-S TM Quality Indexes, they would basically resemble the QI development of gutted fish.

4.1 Harvesting procedures and handling stress

  • Fish from the volume confined by the sweep-net were collected by immersing a tub into the cage.
  • Even though the fish became calm after AQUI-S TM was added to the tub it would not matter anymore since they were already severely stressed by crowding.
  • As with the ice-slurry fish, the AQUI-S TM fish, with core temperature 29.2 o C, were also very stiff during sampling, strongly indicating vigorous muscle activity during crowding caused rapid depletion of ATP leading to early rigor onset.
  • Thus, achieving rested harvest of pompano in cage cultures did not seem to be a feasible option.
  • Absence of VORs of the AQUI-S TM fish in the present study indicated that good welfare was achieved during the stunning process per se.

5. Conclusions

  • Due to the extreme excitability of shortfin pompano, the outlook for achieving rested harvest in floating cage systems seemed to be rather far-fetched.
  • Since both ice-slurry and AQUI-S TM harvesting methods were preceded by very stressful fish crowding and transfer operations, all fish were harvested in an exhausted condition showing method of harvesting did not matter when the principles of rested harvest is considered.
  • This effect was offset after ice storage for one day.
  • In contrast, changes in eye color were more evident.
  • The present study indicated that the shelf life of exhausted shortfin pompano stored in ice at constant low temperatures was about 18 d.

Did you find this useful? Give us your feedback

...read more

Content maybe subject to copyright    Report

1
Harvesting procedures, welfare and shelf life of ungutted and 1
gutted short-fin pompano (Trachinotus falcatus) stored in ice 2
3
4
5
6
Ulf Erikson 7
SINTEF Ocean, 7010 Trondheim, Norway 8
Hanh T. M. Truong
a
, Dung V. Le
ab
, Phuong D. Pham
a
, Niels Svennevig
a
and Van T. Phan
a
9
a
Research Institute for Aquaculture No.1, Hanoi, Vietnam 10
b
Vietnam National University of Agriculture, Hanoi, Vietnam 11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

2
ABSTRACT 32
33
Shortfin pompano (Trachinotus falcatus) were harvested from a floating cage culture. Handling stress 34
(blood pH, white muscle pH, and rigor mortis) and welfare (''eye roll'') were determined for two 35
harvesting methods: (i) batch netting and transfer to ice-slurry where the fish were killed and chilled 36
(commercial method) and, (ii) transfer of fish to a tub immersed in the cage before it was lifted onto a 37
barge where the fish were euthanised by an AQUI-S
TM
overdose. Half of the ice-slurry fish were gutted. 38
All fish were subsequently stored for 18 d in ice for assessment of freshness (total bacterial counts, 39
TBC and Quality Index Method, QIM) as well as skin and eye color. A modified QIM scheme for 40
European sea bass was used with demerit points ranging from 0 to 18. Due to excessive swimming 41
during crowding, both ice-slurry and AQUI-S
TM
fish were harvested in an exhausted condition. Upon 42
sampling, none of the fish exhibited ''eye roll'', indicating they were either unconscious or dead. Since 43
the ice-slurry fish were not stunned immediately, the welfare of the fish might have been 44
compromised. During rapid chilling, the fish developed cloudy eyes. The asset of using AQUI-S
TM
was 45
possibly better fish welfare during the stunning and euthanising phase since exposure to ice-slurry was 46
associated with escape swimming behaviour and slow death. Shortly after harvesting there were some 47
significant differences between harvesting methods in terms of skin color. They were, however, largely 48
offset by storage for one day. Only a few minor changes in skin color took place during further storage. 49
Changes in eye color were more prominent than for skin. After storage for more than a week, the TBCs 50
of gutted fish were significantly higher compared with ungutted fish (P<0.05). AQUI-S
TM
fish (ungutted) 51
exhibited the lowest TBCs for about the first two weeks indicating exposure to the anesthetic reduced 52
bacterial growth. After 18 d, none of fish from all treatments had yet reached the generally accepted 53
spoilage level of 7 log cfu g
-1
. At this point, the fish had not reached the maximum attainable QI score 54
of 18. High linear correlations (R 0.972, P < 0.001) were achieved for development of QI during ice 55
storage where the ungutted and AQUI-S
TM
treatments were practically similar. The modified QIM 56
scheme was considered suitable for pompano. The shelf life was tentatively considered to be 57

3
approximately 18 d, although this should be verified by other, supplementary methods. To prolong 58
shelf life, it is recommended that pompano is not gutted before they are subjected to chilled storage.
59
60
Key words: Shortfin pompano, Harvesting, Stress, Welfare, Ice storage, QIM, TBC, AQUI-S
TM
61
62
63
1. Introduction 64
65
Since the 1960s, it has been recognized that farming of the different species of the genus Trachinotus 66
spp of the Carangidae family seems to be promising due to its excellent flesh quality (pompano is one 67
of the most highly desired marine fishes) and high market prices (Berry and Iverson 1967). Lazo et al. 68
(1998) concluded, based on studies of growth, feed efficiency and survival of juvenile Florida pompano 69
(Trachinotus carolinus), that the species is suitable for aquaculture due to its ready adaption to culture 70
systems, acceptance of formulated feeds, and rapid growth rates. Shortfin pompano (Trachinotus 71
falcatus), endemic to the subtropical and tropical western parts of the Atlantic Ocean, was introduced 72
to Asia in the 1990s and eventually to Vietnam. The annual production of pompano in Vietnam is about 73
700 tons where the market-sized fish (400-600 g) are traded locally or exported to USA, Korea and 74
Japan (McMaster and Gopakumar 2016). 75
Before harvest, the quality of farmed fish is dependent on several factors such as genetics, feed 76
composition, water quality, farming practices and health condition. Once harvested, freshness is the
77
most important quality trait for raw fish. Freshness can be assured by effective and consistent chilling 78
from farm or processing plant to consumers as well as by minimizing storage time before consumption. 79
Harvesting procedures such as pre-slaughter crowding, pumping and killing methods can be stressful 80
and might, depending on fish species, unfavorably affect flesh quality (Lowe et al. 1993; Sigholt et al. 81
1997; Bagni et al. 2007; Knowles et al. 2007; Roth et al. 2009; Bahaud et al. 2010; Erikson et al. 2011; 82
Matos et al., 2011). Choice of stunning method is important to safeguard fish welfare (Erikson 2011). 83
For example, to minimize handling stress during harvesting (rested harvest) and to provide good 84

4
welfare, AQUI-S
TM
can be a good option (Jerrett et al. 1996; Bosworth et al. 2007; Erikson 2011). 85
Alternatively, when used correctly, automated electrical or percussion stunning methods can also 86
provide good fish welfare by rendering the fish unconscious instantly (Lambooij et al. 2008, 2010; 87
Sattari et al. 2010). However, the shelf life of king salmon (Oncorhynchus tshawytscha) is not affected 88
by harvesting method (Fletcher et al. 2003). Different aspects of fish welfare and stress related to 89
slaughter methods and fish quality are reviewed by Poli et al. (2005). Following harvesting, quality 90
changes during storage of fish are mostly attributed autolysis followed by bacterial activity (Liston 91
1980). Depending on storage temperature and storage time, a wide range of chemical reactions 92
gradually take place in the flesh leading to reduced product quality (Huss 1995). 93
Regarding the effect of gutting on fish quality, it is in many cases found that shelf life is prolonged when 94
the viscera is removed after slaughter including proper washing of the belly cavity. On the other hand, 95
gutting implies that the belly cavities are exposed to either chilled water (such as in ice-slurry tubs after 96
slaughter) or air (on ice during storage) rendering them susceptible to microbial invasion, oxidation or 97
discoloration (Borderias and Sánchez-Alonso 2011). Shelf life is inherently linked to food safety by the 98
activity of microorganisms. However, the eating quality of fish is a rather complex issue and shelf life 99
can therefore be defined by various quality parameters. With rainbow trout (Oncorhynchuss mykiss) 100
as example, the shelf life of ungutted chilled fish is considered 14 d (Dawood et al. 1986). Regarding 101
the effect of lipids on the sensory quality of rainbow trout, they were resistant to oxidation during ice 102
storage for up to 14 d. Changes were related to oxidation product decomposition being more intensive 103
in whole than in gutted fish. It was concluded that this species of fish has a shelf life of at least 14 d, 104
and since gutting resulted in delayed autolytic changes, the shelf life of gutted fish was extended by at 105
least 2 to 3 d (Kolakowska et al. 2006). In contrast, based on postmortem changes of biogenic amines 106
and nucleotide degradation of inosine monophosphate to hypoxanthine, combined with sensory 107
evaluation, ungutted and gutted rainbow trout stored in ice were of acceptable quality for only 5 and 108
6 d, respectively (Rodriguez et al. 1999). In gilthead seabream (Sparus aurata), among several 109
measured quality parameters, the only effects of gutting were lower intensity of rigor mortis and a 110

5
drop in the bacterial load. After around 12 to 14 d, all fish had passed sensory and bacterial rejection 111
thresholds (Tejada and Huidobro 2002). In case of sea bass (Dicentrarchus labrax) stored in ice, the 112
shelf life of ungutted and gutted fish, as assessed by overall acceptability sensory scores and 113
microbiological activity, was considered 13 and 8 d, respectively (Papadopoulos et al. 2003). 114
The Quality Index Method (QIM) is a method for evaluating fish freshness by sensory attributes 115
(Hylding and Green-Petersen 2004). The method is robust and is relatively simple to use in practice. QI 116
schemes have therefore been adapted for several fish species (see Seafish 2010). A review of the 117
usefulness of employing QIM in different contexts for assessing freshness and shelf life of several fish 118
species is given by Bernardi et al. (2013). 119
Regarding pompano, data on postharvesting issues, flesh quality and storage are scarce. Gao et al. 120
(2014) studied the use of rosemary extract in combination with nisin to extend shelf life of pompano 121
(Trachinotus ovatus) fillets over a period of 15 d at 4
o
C. The following indices of quality were employed: 122
peroxide value, thiobarbituric acid, total volatile basic nitrogen, trimethylamine, pH, K-value, texture, 123
color as well as sensory and microbial characteristics. Since addition of rosemary and nisin improved 124
quality by affecting several of the mentioned parameters including microbial growth, it was concluded 125
that the shelf life of fillets may be extended by adding these constituents. The proximate composition 126
of the cultured 400-500 g pompano used in the study was: 68.4 % moisture, 17.3 % crude protein, 10.3 127
% lipid and 1.8 % ash. 128
To our knowledge, no peer-reviewed studies are available concerning effects harvesting method and 129
gutting of shortfin pompano. Therefore, the objective of the study was to provide such data. Another 130
objective was to evaluate whether the Quality Index Method scheme, originally intended for sea bass 131
(Dicentrarchus labrax), would also be appropriate for assessing loss of freshness during ice storage. 132
Since pompano are most commonly traded as whole fish in the market, the external appearance of 133
the fish is also important. In such a context, skin and eye color are relevant factors for the consumers 134
perception of the product. Hence, emphasis was also put on color assessment throughout storage. 135

Citations
More filters

Journal ArticleDOI
01 Jun 2019-Heliyon
TL;DR: Results indicated that seabream stunning/slaughtering and storage using EOs+β-CD ice improved the quality of fresh fish and extended the shelf-life up to 4 days.
Abstract: Ice containing essential oils (EOs) nanoencapsulated in β-cyclodextrins (β-CD) (named as EOs+β-CD ice) was used for stunning/slaughtering by hypothermia in ice slurry, and for ice storage of gilthead seabream. Clove essential oil (CEO) was used at fish stunning/slaughtering, while ice storage of whole fish was performed using a combination of carvacrol, bergamot and grapefruit EOs (CBG). Inclusion complexes CBG+β-CD were characterized, and antimicrobial effect was also evaluated. The kneading method used to form inclusion complexes with CBG showed a good complexation efficiency. Microbial, physical-chemical and sensory analyses were carried out to assess the quality changes of fresh whole seabream during ice storage at 2 °C for 17 days. Results (microbial, chemical and sensorial) indicated that seabream stunning/slaughtering and storage using EOs+β-CD ice (in low doses of 15 mg/kg ice for stunning, and 50 mg/kg ice for ice storage) improved the quality of fresh fish and extended the shelf-life up to 4 days.

15 citations


Cites methods from "Harvesting procedures, welfare and ..."

  • ...The assessment of fish was conducted using the Tasmanian Food Research unit (TRFU) system modified by Cakli et al. (2007) and Erikson et al. (2019), and developed as quality index method (QIM)....

    [...]


Journal ArticleDOI
TL;DR: No significant differences were observed between the harvesting methods, regarding fish appearance, microbial spoilage and sensory scoring and subsequently shelf life, but significantly lower hardness was recorded in fish harvested using the electric stunner, compared to the fish killed with slurry ice of the same harvesting period.
Abstract: The objective of this study was to evaluate the effect of harvest practices and slaughter method on stress, quality and shelf life of whole fish (gilthead sea bream, European sea bass and red sea bream) towards the development of a humane slaughter practice. The use of hook and line resulted in significantly lower plasma cortisol and glucose in European sea bass and gilthead sea bream. Water temperature at harvest affected significantly the concentrations of stress indicators (plasma cortisol and glucose), mainly in European sea bass and gilthead sea bream. No significant differences were observed between the harvesting methods, regarding fish appearance, microbial spoilage and sensory scoring and subsequently shelf life. However, significantly lower hardness was recorded in fish harvested using the electric stunner, compared to the fish killed with slurry ice of the same harvesting period. Shelf life ranged between 13–18 days for gilthead seabream, 10–16 days for European sea bass and 10–14 days for red sea bream, depending on harvesting period.

5 citations


Journal ArticleDOI
26 Nov 2020-Foods
TL;DR: Using CO encapsulated in β-CD for anesthetizing fish can be regarded as an improved fish-stunning technique that reduces the anesthesia-induction time, decreases the stress response, and extends the shelf life of fresh fish.
Abstract: In the aquaculture industry, fish are stunned using a wide range of methods, but all of them trigger stress responses and affect the fish flesh quality. Chilled water is considered one of the most efficient methods, but even this is not a stress-free experience for the fish. Anesthetics included in the ice slurry or in water could decrease this stress and delay the loss of flesh quality. In this work, we analyze the effect of clove oil (CO) nanoencapsulated in β-cyclodextrins (β-CD) (CO + β-CD), incorporated in the stunning bath, on the stress response and the organoleptic attributes of fresh marine and freshwater fish from four economically important fish species: Atlantic salmon, European seabass, Nile tilapia, and Rainbow trout. CO + β-CD reduces the time required to induce anesthesia, independently of water salinity, habitat or water temperature. The plasmatic glucose and cortisol levels decreased in all four species, although the concentrations of CO varied between species. Moreover, plasmatic lactate level differed between the marine and freshwater fish. The use of CO + β-CD extended the shelf life of fish from all the species studied (by 3-7 days). In conclusion, using CO encapsulated in β-CD for anesthetizing fish can be regarded as an improved fish-stunning technique that reduces the anesthesia-induction time, decreases the stress response, and extends the shelf life of fresh fish.

4 citations


Journal ArticleDOI
TL;DR: Determination of the variability associated with assessors, product, and correct structure of datasets for statistical analysis, will improve the predictive power of the method, but it could lead to an increase in the method complexity that would drive it away from the industry's needs for fast and easily implemented methods.
Abstract: Background The Quality Index Method (QIM) is a widely used approach for fish sensory grading, based on a structured scaling for freshness measurements, providing information concerning the fish freshness status, as a prediction of the remaining shelf-life for specific species or products. However, its tendency to be used in an oversimplified way and other common misapplications could lead to discredit of a methodology with great potential. Scope and approach Review the principles of QIM methodology, discussing its concept, applications, and understand their limits, as a useful strategy to propose improvements, reinforce its predictive power and consequent acceptability. Key findings and conclusions: QIM methodology is based on a compromise between the number of fish samples necessary and the number of attributes, with sensory relevance in fish spoilage, that allows verifying if quality requirements are fulfilled. However, the assumptions inherent to the method, undermine the reliability of the shelf-life predictions. Determination of the variability associated with assessors, product, and correct structure of datasets for statistical analysis, will improve the predictive power of the method. However, it could lead to an increase in the method complexity that would drive it away from the industry's needs for fast and easily implemented methods.

2 citations


Journal ArticleDOI
26 Feb 2021
TL;DR: The quality index method (QIM) is widely used for fish sensory assessment, but there are hardly any studies on quality changes in fish that have been previously frozen.
Abstract: The quality index method (QIM) is widely used for fish sensory assessment, but there are hardly any studies on quality changes in fish that have been previously frozen. A QIM scheme was developed f...

References
More filters

Journal ArticleDOI
TL;DR: The increasing resistance of microorganisms to conventional chemicals and drugs is a serious and evident worldwide problem that has prompted research into the identification of new biocides with broad activity.
Abstract: The increasing resistance of microorganisms to conventional chemicals and drugs is a serious and evident worldwide problem that has prompted research into the identification of new biocides with broad activity. Plants and their derivatives, such as essential oils, are often used in folk medicine. In nature, essential oils play an important role in the protection of plants. Essential oils contain a wide variety of secondary metabolites that are capable of inhibiting or slowing the growth of bacteria, yeasts and moulds. Essential oils and their components have activity against a variety of targets, particularly the membrane and cytoplasm, and in some cases, they completely change the morphology of the cells. This brief review describes the activity of essential oils against pathogenic bacteria.

924 citations


Journal ArticleDOI
Ryozo Fujii1
TL;DR: The elaborate mechanisms regulating chromatophores in these lovely aquatic animals are described and it is indicated that some paracrine factors such as endothelins (ETs) are involved in these processes.
Abstract: Chromatophores, including melanophores, xanthophores, erythrophores, leucophores and iridophores, are responsible for the revelation of integumentary coloration in fish. Recently, blue chromatophores, also called cyanophores, were added to the list of chromatophores. Many of them are also known to possess cellular motility, by which fish are able to change their integumentary hues and patterns, thus enabling them to execute remarkable or subtle chromatic adaptation to environmental hues and patterns, and to cope with various ethological encounters. Such physiological color changes are indeed crucial for them to survive, either by protecting themselves from predators or by increasing their chances of feeding. Sometimes, they are also useful in courtship and mutual communications among individuals of the same species, leading to an increased rate of species survival. Such strategies are realized by complex mechanisms existing in the endocrine and/or nervous systems. Current studies further indicate that some paracrine factors such as endothelins (ETs) are involved in these processes. In this review, the elaborate mechanisms regulating chromatophores in these lovely aquatic animals are described.

396 citations


Journal ArticleDOI
TL;DR: This review synthesizes the sublethal physiological and behavioural consequences of cold-shock stress on fishes, identifies natural and anthropogenic sources ofcold shock, discusses the benefits of cold shock to fisheries science and describes mitigation and management efforts.
Abstract: Rapid decreases in water temperature may result in a number of physiological, behavioural and fitness consequences for fishes termed ‘cold shock’. Cold-shock stress occurs when a fish has been acclimated to a specific water temperature or range of temperatures and is subsequently exposed to a rapid decrease in temperature, resulting in a cascade of physiological and behavioural responses and, in some cases, death. Rapid temperature decreases may occur from either natural (e.g. thermocline temperature variation, seiches and storm events) or anthropogenic sources (e.g. varied thermal effluents from power generation and production industries). The magnitude, duration and frequency of the temperature change as well as the initial acclimation temperatures of individuals can influence the extent of the consequences of cold shock on fishes. Early research on cold shock focused on documenting mortality events associated with cold shock. However, in recent years, a shift in research has occurred where the focus of cold-shock studies now involves characterizing the sublethal effects of cold shock in terms of the stress response in fishes. This shift has revealed that cold shock can actually be used as a tool for fisheries science (e.g. to induce polyploidy). The cold-shock stress response offers opportunities to develop many exciting research questions, yet to date, cold-shock research has been largely unfocused. Few studies attempt to link laboratory physiology experiments with ecologically relevant field data on behaviour, growth, bioenergetics and fitness. Additional research will allow for the development of more focused and robust management policies and conservation initiatives. This review synthesizes the sublethal physiological and behavioural consequences of cold-shock stress on fishes, identifies natural and anthropogenic sources of cold shock, discusses the benefits of cold shock to fisheries science and describes mitigation and management efforts. Existing knowledge gaps and opportunities for future cold-shock research are presented.

246 citations


Journal ArticleDOI
Abstract: Salmon slaughtered by standard routines (control) or stressed by confinement for 10 min before stunning and then stored at 0.4 or 3.3°C for 9 days were compared. Handling stress led to lower muscle phosphocreatine (p<0.001), adenosine-5′-triphosphate (p<0.05) and shorter pre-rigor period. Storage temperature affected external quality index, white muscle pH and K-value (degradation products of ATP). Stress produced a softer fillet (p<0.001). A lower breaking strength (p<0.01) was found in fish stored at 0.4°C. Sensory tests distinguished the control/stress groups within the 0.4°C chilling regime and the 0.4°C/3.3°C chilling groups within the control regime. Stress caused a lower score for texture (p<0.05) both at 0.4 and 3.3°C and for odor at 3.3°C in a descriptive sensory test. No detectable effects of stress or storage temperature were found on flavor or color.

227 citations


Journal ArticleDOI
TL;DR: This work reviewed some of the most used indices of stress at the time of slaughter, commercial slaughter methods and related stress effects on physical and biochemical parameters of fish quality to indicate that, although of some results appear contradictory, pre-slaughter and slaughter stressful practices could have an important effect on the flesh quality in fish.
Abstract: . A reliable assessment of animal welfare-suffering and of its impact on product quality requires a multidisciplinary approach that takes into account fish behaviour and the different biochemical and physiological processes involved. This might be done by the contemporary study of changes of indicators of brain function, endocrine responses, post mortem tissue biochemical processes and quality changes. This work reviewed some of the most used indices of stress at the time of slaughter, commercial slaughter methods and related stress effects on physical and biochemical parameters of fish quality. The set of the available data seemed to indicate that, although of some results appear contradictory, pre-slaughter and slaughter stressful practices could have an important effect on the flesh quality in fish. A clear effect emerged mostly on the physical properties of flesh, because severe stress at slaughter time exhausted muscular energies, produced more lactic acid, reduced muscular pH, increased the rate of rigor mortis onset. In this way they could have significant negative effects on technological traits, flesh quality and keeping quality of fish. Asphyxia and electrically stunned fish were more stressed than spiked, knocked and live chilled fish. Combining various methods together might be a more satisfactory strategy for both animal welfare and product quality.

223 citations