RAF/87/008/DR/65/91/E - Preservation of Fish at Sea: A Comparative Study Conducted in the Seychelles Between Non-Gutted and Gutted Fish Preserved in Ice.













Table of Contents


by

G. Carrara1 and G. Lablache2

1 FAO/South West Indian Ocean Project (SWIOP).
2 Seychelles Fishing Authority (SFA).

April 1991
RAF/87/008/DR/65/91/E

REGIONAL PROJECT FOR THE DEVELOPMENT & MANAGEMENT OF FISHERIES IN THE SOUTHWEST INDIAN OCEAN

PROJET REGIONAL POUR LE DEVELOPPEMENT ET L'AMENAGEMENT DES PECHES DANS L'OCEAN INDIEN SUD-OCCIDENTAL

c/o UNITY HOUSE, P.O. BOX 487, VICTORIA, MAHE, SEYCHELLES

TELEPHONE: 23773
TELEX: 2254 SWIOP SZ

FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS UNITED NATIONS DEVELOPMENT PROGRAMME SEYCHELLES FISHING AUTHORITY

The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever by the Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area of its authorities or concerning the delimitation of its frontiers. The views expressed are those of the authors.

Bibliographic Entry

Preservation of fish at sea: A comparative study conducted in the Seychelles between non-gutted and gutted fish preserved in ice SWIOP/SFA 1991: FAO/UNDP RAF/87/008/DR/65/91/E: 14p.

This electronic document has been scanned using optical character recognition (OCR) software and careful manual recorrection. Even if the quality of digitalisation is high, the FAO declines all responsibility for any discrepancies that may exist between the present document and its original printed version.


Table of Contents


1. Introduction

2. Background

3. Description of preservation methods

The conventional technique
Method used on SFA research boat (Treatment 1)
Alternative method (Treatment 2)

4. Objectives

5. Methodology

6. Results

Gutting time
Cooling time
Fish quality

7. Conclusion

Appendix 1. Fish core temperature readings for the two treatments (gutted and ungutted fish).

Appendix 2. Results of fish quality tests (Experiment 1)

Appendix 3. Results of fish quality tests for gutted fish (Experiment 2)


1. Introduction

The purpose of this study was to investigate the feasibility of storing ungutted fish on ice after it had been previously cooled down in a slurry of ice and seawater. A comparative experiment was undertaken to evaluate this method in relation to that used on the SFA research vessel "Etelis", where fish is immediately placed in a ice slurry, then cleaned and gutted when time permits before storing on ice. The SFA method is the one recommended for use on board local fishing boats. Time lost to fishing due to gutting fish at sea was also one of the elements under investigation.

The Research Section of the Seychelles Fishing Authority undertook the responsibility for the fishing operations and overall implementation of the experiment. The SMB Fish Division provided support and necessary facilities for the shore part of the experiment. Mr J.C. Hoareau of the SMB Fish Division, Mr J. Charles and Mr L. Accouche of the Veterinary Division carried out the fish quality tests. The FAO/SWIOP provided technical support and one Biologist/Statistician.

2. Background

Fishing is the second most important economic activity in the Seychelles. The local artisanal fishery lands around 4,000 - 5,000 tonnes of fish annually. Nearly 400 boats are engaged in this fishery. The largest vessels of the fleet (9 to 16 m) fish furthest offshore, principally on the Mahé Plateau. They are equipped with 2 to 3 tonne insulated boxes for storage of fish on ice and they can stay at sea for up to 10 days.

The high-valued species of the grouper and snapper family which are taken in this fishery are an important export commodity. Proper fish handling and preservation is therefore an important aspect of fishing operations, in order to maintain the required fish quality standards for both the export and domestic markets. More efficient but labour demanding fishing techniques such as deep-water gillnetting, which is currently under research by SFA, also prompted the consideration of alternative preservation techniques on board in order to allow more time for fishing.

3. Description of preservation methods


The conventional technique
Method used on SFA research boat (Treatment 1)
Alternative method (Treatment 2)


The conventional technique

On board the local fishing boats engaged in the offshore fishery, the fish is normally gutted and gilled throughout the fishing operations and is kept in the hold on top of the ice until the end of the day. During this time, the fish will often be left on deck (under the sun) before and after cleaning, and once placed in the hold only the lowermost fishes will be slowly cooled.

Most of these boats have no pumped sea-water and during gutting operations the fish is washed in sea-water brought on deck with buckets. Consequently, the tendency is to use the same water to wash many fish, with the risk of spreading bacteria in the fish flesh exposed by gutting. At the end of the day, the catch is returned on deck and then re-arranged in the hold in layers separated by crushed ice. The holds are often poorly insulated and there are some reports of bilge water seeping into the ice-boxes.

Method used on SFA research boat (Treatment 1)

During fishing operations the fish caught is stored in a plastic ice-box containing a rich slush of ice and sea-water (3:1 ratio). At the end of the day or whenever the fishing operations permit, the fish is removed from the chilled sea-water for cleaning. Running sea-water is used for washing the fish, which is then iced down in properly insulated holds in the same manner as above. This method results in an unwanted rise in the temperature of the fish during the gutting operations on deck, prior to stocking it on ice.

Alternative method (Treatment 2)

The fish, which has been cooled in the ice/sea-water slurry as described above, is stored directly in the insulated holds in layers separated by ice, without gutting and gilling.

In relation to this method, SMB officers have advanced the hypothesis that fish stored without gutting and gilling will spoil faster particularly in the gut area. The landing of large quantities of non-gutted fish will necessitate arrangements with SMB for the gutting and disposal of wastes.

4. Objectives

The objectives of this experiment were to:

1) quantify the time lost to fishing operations while gutting and gilling the fish,
2) produce data on cooling times,
3) and compare the quality and storage life of the fish after 7-10 days,

in respect to fish treated using the SFA and the alternative methods respectively. Both these methods involve the use of chilled sea-water and proper packing in well-insulated holds. They are thus considered preferable to the handling practices in the artisanal fleet.

5. Methodology

Fishing activities took place over a three day period, from the 22nd-24th January 1991 (Experiment one).

The fish used in this experiment were taken on the second and third day at sea. Three insulated plastic ice-boxes of 300 Kg capacity were utilised. One box was used for cooling all the fish caught in chilled sea-water and two identical ice-boxes were positioned at the stern of the research boat "Etelis" for icing and storage of the gutted and non-gutted fish separately. These plastic boxes are not fitted with drainage holes, and the melted ice water had to be pumped out daily.

In total, 148 fish of identical species and similar size were selected for the two "treatments", covering several species and sizes. Each fish selected for the experiment was individually marked by attaching a string and number as it came on board. Fish were then paired by species and size and joined with a third string before cooling in the slurry.

At the end of the day, each pair of fish was separated and the weight of each recorded. One of the paired fish was put aside for gutting (Treatment 1) and the other was placed in a container for immediate packing in ice (Treatment 2).

During gutting operations, the number of fishermen involved, the total gutting time and the number of fish gutted were recorded in order to estimate the number of fish gutted per unit of time in this non-fishing operation and thus quantify the additional work load for the fishermen. Additional data were collected on a another dropline fishing trip, giving an overall gutting rate averaged over a three day period.

At the end of the fishing trip, the two ice-boxes containing the fish selected for the experiment were unloaded (full) from the vessel and stored at normal temperature on SMB premises. Ice was added to both boxes every day as necessary and the water from the melted ice was pumped out of the ice-box. Despite this procedure, the absence of proper drainage caused the fish eyes to become opaque. Water retention most probably caused the further spread of bacteria, subsequently reducing the storage life.

As from the seventh day of storage of the fish, 15 fish (of roughly even size distribution: 5 small, 5 medium and 5 large) were selected for "quality" tests from each box daily. The tests were continued for four days (ie. ten days of storage life). The remaining fish were retained in the iceboxes to determine an approximate storage life of fish for each treatment. The tests, which were resumed on the 13th day of storage, ended on the 14th day.

The following organoleptic criteria were recorded for each fish (with a rating of 1 to 3, ranging from good to bad):

1) Rigidity of the flesh (good, medium, low);
2) Consistency of the flesh (good, medium, low);
3) Appearance of the eye (good, medium, bad);
4) Smell of the gut cavity (good, medium, bad);
5) Appearance of the gut cavity (good, medium, bad).

The above grading was made by one veterinary officer and one quality control officer from SMB, providing independent ratings. Based on the above freshness scores, the results were grouped into the following grades used by SMB:

Grade

E: Export (whole fish)
E/F: Export (in fillets)
L: Local (whole fish)
L/F: Local (in fillets)
R: Reject

Prime quality grade for export (Grade E) was attributed to fish which scored one for the flesh texture, gut odour and appearance and at least two for the eye appearance. The condition of the eye was not considered to be critical due to the problem of water retention in the ice-boxes which was previously noted. In the case where a score of two (medium) was assigned to the eye appearance and/or the gut appearance with the other characteristics good, the fish was judged to be suitable for export in fillet form (Grade E/F). Fish classified in the local grades (L and L/F) depended upon the deterioration of a combination of the sensory criteria recorded. A bad rating (score of three) for the appearance of the gut cavity resulted in the fish being considered unfit for consumption (Reject), whereas in the case where the same score was assigned to the other criteria, the fish was still considered fit for processing as Grade L or L/F (Local or local/fillet).

Since this experiment was run on fish of at least seven days old, at which time the deterioration of the gut cavity (in Treatment 2) had already set in, a second sample of 60 non-gutted fish treated in the same manner as described above was taken on another fishing trip on the 21st February 1991 (Experiment 2). The purpose of this second test was to establish the approximate time at which the "belly burns" occur.

6. Results


Gutting time
Cooling time
Fish quality


Gutting time

Details of the gutting operations over a three day period are given below:

Date

Gutting time
(hrs)

No. of men

Quantity gutted

Weight (kg)

No.

23/01/91

1.5

3

473.2

126

19/02/91

1.0

3

472.6

170

20/02/91

1.0

3

357.9

146

Total

3.5

9

1,303.7

442

Average gutting rate



124 kg/man/hour or 42 fish/man/hour


A total of 1,303.7 kg of fish (442 fish) were gutted by three men over a period of 3.5 hrs.

This is equivalent to 124 kg/man/hr (or 42 fish/man/hr). This result would therefore indicate that the gutting time on board schooners is not excessive. A schooner which makes an average of one tonne per trip, would involve a total of eight man hours for the gutting operations.

Gutting time would however become an important factor for boats using more efficient techniques such as deep-water gillnetting and droplines where daily catch rates of at least half a tonne are expected.

Cooling time

Figure 1 (and Appendix 1) shows the variation in core temperature for a sample of fish whilst in chilled seawater and under storage in ice for the two treatments, gutted and ungutted fish respectively. The fish core temperature dropped to 0°C after 2-4 hrs immersion in chilled sea-water (at -1°C), depending upon the size of the fish.

Figure 1.a: Changes in core temperature - GUTTED FISH

Figure 1.b: Changes in core temperature - UNGUTTED FISH

After the fish were removed from the chilled seawater container for cleaning (Treatment 1), an average rise in core temperature of 13.5°C was observed before storage on ice. For the large fish, the core temperature increased by 7°C compared to 16-18°C for the small to medium fish.

After packing the ungutted fish in ice (Treatment 2), the core temperature showed very slight variation. The temperature initially increased by an average of one degree over a period of 3 hours, stabilising around 0°C after 5 hours of storage. During this period, the gutted fish (Treatment 1) showed a fast drop in temperature of 12°C after four hours of storage (from an average of 13.6° to 1.3°C). It is to be noted, however, that these temperature changes would tend to be lower than in commercial operations, due to good icing procedure and small volume of fish being stored. Under commercial conditions, fishermen would use less ice and place a layer of ice for several layers of fish, with a larger quantity at the top of the hold. The hold, which is usually separated into two compartments of one tonne each and is therefore larger than that used in this experiment, could also influence these results. The temperature increase as a result of gutting would also tend to be greater.

Fish quality

The quality of the fish samples treated in the two different ways is summarised below, using the grading categories adopted by SMB which were described in Para 5, whereas the detailed results of the quality tests are given in Appendix 2.

Day

GUTTED FISH (%)

SMB standard

7th

8th

9th

10th

13th

14th

E

100

100

83

33

0

0

E/F

0

0

17

33

0

0

L

0

0

0

33

0

0

L/F

0

0

0

0

100

100

R

0

0

0

0

0

0

No. of samples

15

17

23

6

10

3

Total






74

Day

UNGUTTED FISH (%)

SMB standard

7th

8th

9th

10th

13th

14th

E

43

67

14

0

0

0

E/F

14

28

24

0

0

0

L

43

6

19

67

0

0

L/F

0

0

19

17

100

67

R

0

0

24

17

0

33

No. of samples

14

18

21

6

11

3

Total






73

Chilled sea-water treatment, proper handling and gutting of fish produced high quality fish after nine days storage on ice (Treatment 1), despite some water retention in the ice-box. All the fish examined were of export quality, of which 17% qualified only as export in fillet form on the 9th day (due to eye appearance and gut cavity smell). It should be noted that the condition of the eyes was influenced by water retention in the ice boxes which could not be properly drained. Compared to normal schooner operations, around 35-40% of the catch is of export quality after a trip of nine days (Hoareau/Tirant, SMB pers. com.).

During the same period, a significant proportion of the non-gutted fish (Treatment 2) did not score the degree of freshness required for exports. This increased to 62% by the 9th day after capture. Deterioration in the gut cavity was present on the first day of analysis (7th day after capture) and was the major reason for the lower quality score attributed to the non-gutted fish samples (57% on day 7, 95% on day 8 and 38% on day 9 after capture respectively were of export quality, as whole and filleted fish). From the 7th-9th day of capture, 14-28% of the sample was suitable for exports only in fillet form almost exclusively because of the condition of the gut cavity (belly burns) and later the smell of the gut cavity. While on the 10th day of storage 67% of the gutted fish were still of export quality, none of the ungutted fish scored this high quality of freshness.

These results therefore indicate that the rate of fish spoilage, (according to the scoring system used by SMB Fish Division) is faster for ungutted fish. However, the maximum storage life would seem to be comparable for the two fish samples irrespective of the "treatment" as most of the fish examined were assigned to the local fillet (L/F) category after 13-14 days of storage on ice.

The phenomenon of "belly burns", degradation of the belly cavity as a result of enzymatic action which begins as the fish dies, is known to be associated with the presence of food or bait in the stomach. In the second experiment conducted, it was first noticed in fish three days after capture, though to a limited extent. The results below (also see Appendix 3) show that 20% of fish on days 3-4, 40% on day 5 and 27% on day 6 did not meet the required standard for export as whole fish due to gut discoloration and burns, but were suitable for export as fillets. The data also show a better degree of freshness of the fish compared to that in the first experiment which results from improved drainage of water from the ice-box.

Day

UNGUTTED FISH (%)

SMB standard

2nd

3rd

4th

5th

6th

E

100

73

80

60

67

E/F

0

20

20

40

27

L

0

0

0

0

0

L/F

0

0

0

0

0

R

0

7*

0

0

1

No. of samples

5

15

15

15

15

* one fish rejected due to bruising.

The alternative technique (Treatment 2) using chilled sea-water followed by the icing of the whole fish is therefore not recommended for long trips orientated towards export-quality fish. It however remains interesting for boats operating on short trips (of less than seven days) with high fish tonnages involving important workload. A saving of eight man hours is to be expected for each tonne of fish caught.

7. Conclusion

In order to improve the quality of fish on local schooners, it is recommended that the SMB with the assistance of SFA and the Fish Quality Control Unit (Veterinary Division) promote the introduction of chilled sea-water boxes on board schooners. This will reduce the time during which fish is lying on deck, poor cooling of the fish piled up in the hold and temperature loss in the hold due to frequent opening of the hatches. Where the fish is gutted on board, a second immersion in chilled sea-water should ideally be made in order to rapidly bring down its temperature prior to stocking on ice. However this second procedure can only be possible on more spacious boats, provided that a higher price can be offered, as it would demand a greater effort and more ice.

This procedure could be adopted initially on SMB-contracted schooners against an increase in fish prices. SMB could purchase proper boxes for chilled sea-water and lend them out to fishermen before the trip. After each trip the boxes would then be returned to SMB for washing and sterilising.

Methods to improve fish holds of schooners should also be investigated to prevent problems such as contact with bilge water, poor insulation, crushing of fish resulting from improper packing etc. In order to ensure that the fish holds be properly cleaned out and sterilised, the use of removable holds should be considered.

Appendix 1. Fish core temperature readings for the two treatments (gutted and ungutted fish).

Date

Relative time (hrs)

Time elapsed (hrs)

GUTTED FISH

UNGUTTED FISH

Small

Medium

Large

Average

Small

Medium

Large

Average

23/1/91









0.58

0.58

8.3

11.0

17.2

12.2

8.3

11.0

17.2

36.5

0.67

1.25

2.5

5.5

9.3

5.8

2.5

5.5

9.3

5.8

0.93

2.18

0.0

1.1

4.9

2.0

0.0

1.1

4.9

2.0

0.92

3.10

0.0

0.3

1.8

0.7

0.0

0.3

1.8

0.7

1.00

4.10

0.1

0.0

0.3

0.1

0.1

0.0

0.3

0.1



GUTTING

ICING

1.33

5.43

15.9

17.9

7.1

13.6

-

-

-

-

1.58

7.01

7.1

6.5

3.8

5.8

0.4

2.3

1.3

1.3

2.25

9.26

2.0

0.7

1.2

1.3

0.4

0.0

0.4

0.3

24/1


7.33

16.59

1.3

0.6

0.2

0.7

0.3

0.2

1.5

0.7

8.50

25.09

0.1

0.2

0.0

0.1

0.1

0.8

0.6

0.5

25/1

20.00

45.09

0.3

0.1

0.2

0.2

0.5

-0.1

-0.2

0.1

26/1

24.00

69.09

0.1

-0.1

0.1

0.0

0.0

-0.2

-0.1

-0.1

27/1

25.00

93.09

0.3

-0.1

-0.1

0.0

0.1

-0.1

-0.1

0.0

28/1

26.50

119.59

0.3

-0.1

-0.1

0.0

0.3

-0.3

-0.1

0.0

29/1

23.00

142.59

0.2

-0.1

-0.2

0.0

0.2

-0.2

-0.1

0.0

30/1

25.00

167.59

-0.1

-0.2

-0.1

-0.1

-0.3

-0.2

-0.1

-0.2

31/1

22.00

189.59

0.0

-0.1

-0.1

-0.1

0.0

-0.2

-0.2

-0.1

01/2

25.00

214.59

0.0

-0.2

-0.2

-0.1

0.1

-0.2

-0.2

-0.1

02/2

22.00

236.59

0.1

-0.2

-0.1

-0.1

-0.1

-0.1

-0.2

-0.1

03/2

24.00

260.59

-0.1

-0.2

-0.1

-0.1

-0.2

-0.1

-0.3

-0.2

Appendix 2. Results of fish quality tests (Experiment 1)

2.1 GUTTED FISH

Grading: 1 = good, 2 = medium, 3 = low or bad

Fish No.

Tag Gutted
Wt (Kg)

Species

Rigidity of flesh

Consistency of flesh

Appearance of eye

Gut cavity smell

Appearance of gut cavity

SMB/Vet standard

Day 7 after capture

41

0.8

?

1

1

2

1

1

E

11

6.7

?

1

1

2

1

2

E

53

1.7

?

1

1

1

1

1

E

55

1.7

?

1

1

1

1

1

E

36

1.0

?

1

1

1

1

1

E

24

0.5

?

1

1

3

1

1

E

20

1.4

?

1

1

2

1

1

E

62

1.5

?

1

1

1

1

1

E

70

1.6

?

1

1

1

1

1

E

34

2.5

?

1

1

2

1

1

E

02

1.6

?

1

1

2

1

1

E

52

1.25

?

1

1

1

1

1

E

50

1.4

?

1

1

2

1

1

E

40

1.3

?

1

1

1

1

1

E

Day 8 after capture

17

0.9

V. maconde

1

1

2

1

1

E

88

1.6

Batrican

1

1

2

1

1

E

22

2.5

Batrican

1

1

1

1

1

E

144

2.2

Batrican

1

1

1

1

1

E

26

6.3

Job Jaune

1

1

2

1

1

E

82

3.6

Carang noir

1

1

2

1

1

E

13

1.5

Batrican

1

1

1

1

1

E

6

3.4

Batrican

1

1

1

1

1

E

149

4.5

Batrican

1

1

2

1

1

E

48

1.4

Batrican

1

1

1

1

1

E

89

2.1

Batrican

1

1

2

1

1

E

31

1.2

Batrican

1

1

1

1

1

E

78

2.0

Batrican

1

1

1

1

1

E

46

1.7

Batrican

1

1

2

1

1

E

16

1.3

Batrican

1

1

2

1

1

E

75

3.7

Batrican

1

1

2

1

1

E

110

0.8

V. maconde

1

1

1

1

1

E

Day 9 after capture

64

1.6

Batrican

1

1

2

1

1

E

37

1.2

Batrican

1

1

1

1

1

E

59

3.4

Batrican

1

1

2

1

1

E

43

1.2

Batrican

1

1

1

1

1

E

138

0.8

V. maconde

1

1

1

1

1

E

74

1.5

Batrican

1

1

1

1

1

E

29

1.0

Batrican

1

1

1

1

1

E

66

0.7

V. maconde

1

1

1

1

1

E

07

1.2

Batrican

1

1

1

1

1

E

09

0.8

V. maconde

1

1

1

1

1

E

86

3.3

Batrican

1

1

1

1

1

E

28

2.6

Batrican

1

1

2

1

1

E

84

3.2

Job jaune

1

1

1

2

1

E/F

67

0.6

V. maconde

1

1

1

1

1

E

112

3.5

Carang. noir

1

1

2

1

1

E/F

96

3.5

Etelis

1

1

1

1

1

E

108

2.0

Batrican

1

1

1

1

1

E

129

4.6

Batrican

1

1

1

2

1

E/F

132

2.0

Batrican

1

1

2

1

1

E/F

102

2.0

Batrican

1

1

1

1

1

E

122

1.3

Tioffe

1

1

1

1

1

E

99

4.5

Job jaune

1

1

2

1

1

E

97

5.3

Job jaune

1

1

1

1

1

E

Day 10 after capture

127

1.4

Tioffe

1

1

1

1

1

E

146

1.2

Batrican

1

1

1

1

1

E

148

2.2

Batrican

1

1

2

2

1

L

141

2.5

Batrican

1

1

2

1

1

E/F

58

2.5

Batrican

1

1

1

1

1

E/F

72

1.2

Batrican

1

1

2

2

1

L

Day 13 after capture

92

2.5

Carang. noir

1

1

3

3

2

L/F

91

3.5

Batrican

1

1

3

2

1

L/F

135

2.0

Batrican

1

3

3

1

1

L/F

116

1.8

Batrican

1

3

2

2

1

L/F

117

2.4

Batrican

1

1

2

2

1

L/F

113

1.6

Batrican

1

1

3

2

1

L/F

120

1.2

Batrican

1

1

3

2

1

L/F

123

2.2

Batrican

1

1

3

2

1

L/F

125

3.0

Batrican

1

1

3

2

1

L/F

139

?

Batrican

1

1

3

2

1

L/F

Day 14 after capture

33

1.8

Batrican

1

1

3

3

1

L/F

03

2.0

Batrican

1

3

3

2

1

L/F

93

1.2

Batrican

1

1

3

2

1

L/F

Note:

Batrican:

Pristopomoides filamentosus

Carangue noir:

Caranx lugubris

Etelis:

Etelis carbunculus; E. coruscans

Job Jaune:

Aphareus rutilans

Tioffe:

Epinephelus morrhua

Vielle macondé:

Epinephelus chlorostigma

Vielle rouge:

Cephalopolis sonnerati

2.2 UNGUTTED FISH

Fish No.

Tag Gutted
Wt (Kg)

Species

Rigidity of flesh

Consistency of flesh

Appearance of eye

Gut cavity smell

Appearance of gut cavity

SMB/Vet standard

Day 7 after capture

77

1.8

Batrican

1

1

1

2

1

E

21

2.2

Batrican

1

1

2

1

2

L

12

1.4

Batrican

1

1

1

2

2

L

45

1.6

Batrican

1

1

1

2

3

L

27

2.4

Batrican

1

1

1

1

2

L

90

2.4

Batrican

1

1

1

2

1

E

19

1.3

Batrican

1

1

1

2

1

E/F

25

6.2

Job jaune

1

1

1

1

1

E

73

1.5

Batrican

1

1

1

1

2

E/F

51

1.4

Batrican

1

1

2

1

2

L

57

2.5

Batrican

1

1

1

1

1

E

23

0.5

V. maconde

1

1

2

1

1

E

65

0.8

V. maconde

1

1

1

1

1

E

71

1.0

Batrican

1

1

1

2

2

L

Day 8 after capture

15

1.3

Batrican

1

1

2

1

2

L

42

0.6

V. Maconde

1

1

2

1

1

E

01

1.0

V. maconde

1

1

2

1

1

E

47

1.0

Batrican

1

1

1

1

1

E

32

1.5

Batrican

1

1

1

1

1

E

85

3.4

Batrican

1

1

1

1

1

E

83

3.0

Job jaune

1

1

2

1

2

E/F

54

1.7

Batrican

1

1

1

1

2

E/F

14

1.3

Batrican

1

1

1

1

1

E

38

1.2

Batrican

1

1

1

1

2

E/F

69

1.6

Batrican

1

1

1

1

1

E

04

4.5

Batrican

1

1

2

1

1

E

81

3.1

Carang noir

1

1

2

1

1

E

56

1.3

Batrican

1

1

1

1

2

E/F

60

3.6

Batrican

1

1

1

1

1

E

98

6.0

Job jaune

1

1

1

1

2

E/F

95

4.5

Job jaune

1

1

1

1

1

E

94

2.6

Carang noir

1

1

3

1

1

E

Day 9 after capture

05

2.8

Batrican

1

1

1

1

2

E/F

133

3.0

Batrican

1

1

1

1

1

E

76

3.6

Batrican

1

1

1

1

1

E

87

2.0

Batrican

1

1

1

1

2

E/F

61

1.8

Batrican

1

1

1

1

2

E/F

08

1.2

Batrican

1

1

1

1

3

R

30

1.1

Batrican

1

1

1

2

2

E/F

35

1.1

Batrican

1

1

1

3

1

L

68

0.7

V. Maconde

1

1

2

3

1

E/F

44

1.3

Batrican

1

1

1

1

3

R

63

2.0

Batrican

1

1

1

1

1

E

39

1.5

Batrican

1

1

1

1

3

R

124

3.0

Batrican

1

1

2

2

1

L/F

101

1.8

Batrican

1

1

1

2

3

L/F

115

2.0

Batrican

1

1

1

2

2

L/F

136

1.8

Batrican

1

1

1

2

2

L/F

111

2.8

Carang noir

1

1

2

2

3

R

140

1.7

Tioffe

1

1

2

2

2

L

121

1.2

Tioffe

1

1

2

2

1

L

119

1.2

Batrican

1

1

2

2

3

R

118

2.4

Batrican

1

1

1

1

2

L

Day 10 after capture

147

2.5

Batrican

1

1

1

2

2

L

150

3.5

Batrican

1

1

1

1

1

L

145

3.4

Batrican

1

1

1

1

2

L/F

10

0.8

V. Maconde

1

1

2

2

3

R

137

0.8

V. maconde

1

1

2

2

1

L

143

2.2

Batrican

1

1

1

1

2

L

Day 13 after capture

104

1.8

Batrican

1

1

3

3

2

L/F

100

3.9

Batrican

1

1

3

3

3

L/F

130

4.0

Batrican

1

1

3

3

3

L/F

107

2.0

Batrican

1

1

3

3

3

L/F

105

1.0

Batrican

1

1

3

2

3

L/F

?

1.0

Batrican

1

1

3

2

2

L/F

114

1.0

Batrican

1

1

3

3

2

L/F

126

2.4

Batrican

1

1

3

3

3

L/F

131

1.2

V. maconde

1

1

3

3

3

L/F

109

1.0

V. maconde

1

1

3

3

3

L/F

128

1.2

Tioffe

1

1

2

2

2

L/F

Day 14 after capture

142

4.0

Batrican

1

1

3

3

3

R

?

3.5

Batrican

1

1

3

3

2

L/F

18

0.8

V. maconde

1

1

3

3

3

L/F

Appendix 3. Results of fish quality tests for gutted fish (Experiment 2)

Grading: 1 = good, 2 = medium, 3 = low or bad

Species

Rigidity of flesh

Consistency of flesh

Appearance of eye

Gut cavity smell

Appearance of gut cavity

SMB/Vet standard

Day 2 after capture

V. maconde

1

1

1

1

1

E

V. maconde

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

V. rouge

1

1

1

1

1

E

Day 3 after capture

Batrican

1

1

1

1

2

E/F

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

V. maconde

1

1

1

1

2

E/F

Tioffe

1

1

1

1

2

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

R*

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

V. rouge

1

1

1

1

1

E

Day 4 after capture

Saumon

1

1

1

1

1

E

Tioffe

1

1

1

1

1

E

Tioffe

1

1

1

1

1

E/F

Job jaune

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

V. maconde

1

1

1

1

1

E

Batrican

1

1

1

1

1

E/F

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

2

E/F

Day 5 after capture

Batrican

1

1

2

1

1

E

Tioffe

1

1

1

1

2

E/F

Saumon

1

1

1

1

2

E/F

Tioffe

1

1

1

1

1

E

Tioffe

1

1

1

1

2

E/F

Batrican

1

1

1

1

1

E

Batrican,

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

2

E/F

Batrican

1

1

1

1

1

E

Batrican

1

1

1

1

2

E/F

Batrican

1

1

1

1

1

E

V. maconde

1

1

1

1

1

E

Batrican

1

1

1

1

2

E/F

Day 6 after capture

V. platte

1

1

1

1

2

E/F

Batrican

1

1

1

1

1

E

Saumon

1

1

1

1

1

E

Tioffe

1

1

1

1

3

R

V. maconde

1

1

1

1

1

E

Tioffe

1

1

1

1

2

E/F

Batrican

1

1

1

1

2

E/F

V. maconde

1

1

1

1

1

E

V. maconde

1

1

1

1

1

E

Saumon

1

1

1

1

1

E

Batrican

1

1

1

1

2

E/F

Tioffe

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

V. maconde

1

1

1

1

1

E

Batrican

1

1

1

1

1

E

* fish rejected due to bruising.


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