Previous Page Table of Contents Next Page


5. Results of the fishing experiments

Some of the results of the fishing experiments are commented on below. One should note, however, that most of the fishing forms part of a programme for “swept area” biomass estimation, and for this purpose the trawl stations are positioned in advance more or less randomly and with no intention of obtaining high catch rates. The catch rates thus do not simulate those of a commercial fishery and they are presented here merely to give a rough impression of the general occurrence, composition and abundance offish on the shelf. The results may thus not be directly comparable to catch rates from previous fishing surveys.

The bottom trawl used is a shrimp-cum-fish trawl (see Annex 1). It is uncertain how the efficiency of this trawl with respect to shrimp compares with the special gear used by the commercial shrimp fleet.

Suriname.

The catch records of all trawls stations are shown in Annex II, nos. 609 - 635. Table 1 shows an analysis of catch rates (standardized to kg per hours towing) for all successful bottom trawl hauls by broad groups of fish and for the inner and outer shelf separately. “Demersal” comprises the families Sciaenidae, Ariidae, Pomadasiydae, Serranidae and Lutjanidae and “Pelagic”: Engraulidae, Clupeidae, Carangidae, Scombridae. Sphyraenidae and Trichiuridae. Catch rates for pelagic fish in a bottom trawl is not very meaningful, but as during the previous surveys the indication is a higher availability on the inner shelf. The catch rates for squid were less than in the previous survey, with only one catch exceeding 20 kg/hour.

Table 1. Suriname. Catch rates for main groups in bottom trawl stations standardized to kg/hour.

INNER SHELF

ST. NO.

DEP.

Demersal

Sharks

Shrimp

Pelagic

Squid

Other

620

40

3.80



2.80

12.00

6.20

621

36

4.90

11.60


6.80

2.40

35.60

622

35

14.40



7.00

8.00

35.80

623

30

548.20

19.40


36.00

10.40

138.00

624

22

60.80


9.60

764.80


54.40

625

19

277.80

9.40

7.20

85.20


9.60

626

27

1944.00

32.00

7.30

124.00


1049.40

627

32

32.40


3.00

7.20


82.00

628

40

40.80



48.60


105.30

629

42

180.80



8.20


60.00

630

29

1.80



3.10

7.20

115.80

631

27

99.00

4.00


67.00

58.00

147.80

632

25

39.40

1.40


522.00

14.40

1.80

634

30

12.80


4.40

86.50

3.50

222.50

635

23

35.10

105.00


346.60


58.40

MEAN


219.73

12.19

2.10

141.05

7.73

141.51


OUTER SHELF

ST. NO.

DEP.

Demersal

Sharks

Shrimp

Pelagic

Squid

Other

612

769



56.00



45.40

613

714



67.40



54.35

614

56

30.60

71.00

1.00

73.80

2.60

26.80

616

760



209.60

3.00

40.20

176.10

617

84

344.60

9.60

1.80

53.40


49.80

618

71

200.22


4.80

11.66


165.94

619

63

25.20


6.60

10.40


52.00

MEAN


85.80

11.51

49.60

21.75

6.11

81.48


Table 2 presents an analysis of catch rates by families of demersal fish for the two parts of the shelf. The inner shelf fish community is composed of a multitude of species groups, of which croakers (Orthopristis ruber, Cynoscion jamaicensis) and snappers (Lutjanus synagris, L. purpureus) were dominating. The same species of snappers were also found at the outer shelf, but at bigger sizes, and were dominating in the catches.

Table 2. Suriname. Catch rates by families for demersal fish, kg/hour.

INNER SHELF

ST. NO.

DEP.

Catfish

Croakers

Grunts

Groupers

Snappers

Other

620

40




1.40

2.40

21.00

621

36




1.30

3.60

56.40

622

35



1.00

0.80

12.60

50.80

623

30



120.00


428.20

203.80

624

22

6.40

60.80




822.40

625

19

6.00

259.20

18.60



105.40

626

27


428.00

1476.00

32.00

8.00

1212.70

627

32


2.00

10.00

4.00

16.40

92.20

628

40



33.90

3.00

3.90

153.90

629

42



88.80


92.00

68.20

630

29





1.80

126.10

631

27




3.00

96.00

276.80

632

25


14.40



25.00

539.60

634

30



4.00

5.30

3.50

316.90

635

23


4.10



31.00

510.00

MEAN


0.83

51.23

116.82

3.39

48.29

303.75


OUTER SHELF

ST. NO.

DEP.

Catfish

Croakers

Grunts

Groupers

Snappers

Other

612

769






101.40

613

714






121.75

614

56





30.60

175.20

616

760






428.90

617

84


3.60


4.20

336.80

114.60

618

71


4.11


4.11

192.00

182.40

619

63



3.20

0.80

21.20

69.00

MEAN



1.10

0.46

1.30

82.94

170.46


Table 3 shows the standardized catch rates for the different types of pelagic fish in trawl stations from the inner and outer shelf including also hauls with pelagic trawl. Especially the bottom trawl is selective for different types of pelagic fish and Clupeids and Engraulids will be underrepresented compared with the other groups.

Table 3. Suriname. Catch rates by families of pelagic fish in pelagic and bottom trawl hauls, kg/hour.

INNER SHELF

ST. NO.

DEP.

Sardines

Achovies

Carangids

Scombrids

Barracudas

Other

609

32

2.20


2.40

7.80

0.60

75.60

620

40

0.40


0.40

2.00


22.00

621

36



6.20

0.60


54.50

622

35

0.40


5.00

1.60


58.20

623

30



19.80


16.20

716.00

624

22

313.60

204.80

153.60


19.20

198.40

625

19

18.00

3.60

39.60



328.00

626

27



116.00



3040.70

627

32

2.00


2.00


3.20

117.40

628

40



48.60



146.10

629

42



4.00

4.20


240.80

630

29



3.10



124.80

631

27

1.50


30.50

35.00


308.80

632

25

219.60

273.60

2.20

26.00

0.60

57.00

633


155.20

60.80

6.80

7.40

33.60

303.20

634

30

5.00


81.50



243.20

635

23

169.40

145.60

12.60

6.40

11.20

199.90

MEAN


52.19

40.49

31.43

5.35

4.98

366.74


OUTER SHELF

ST. NO.

DEP.

Sardines

Achovies

Carangids

Scombrids

Barracudas

Other

611

94

0.80


7.40



126.30

612

769






101.40

613

714






121.75

614

56

1.00


39.20

28.60

5.00

132.00

616

760






428.90

617

84

4.20


43.20

6.00


405.80

618

71

2.06


9.60



370.96

619

63

6.80


3.60



83.80

MEAN


1.86


12.88

4.33

0.63

221.36


The catches of small pelagics on the outer shelf are generally low. On the inner shelf the average catch of clupeids, anchovies and carangids are around 50, 40 and 30 kg/hour respectively.

Pooled samples of the length frequencies of the most common of these species are shown in Annex III.

Guyana.

For records of the fishing stations reference is made to Annex II from st. 636 to 678. Table 4 shows the standardized catch rates for the broad groups and for the inner and outer shelf (shallower resp. deeper than 50 m). The mean catches by groups in the tables are in close agreement with the previous survey, except for the pelagics at the outer shelf which is considerably higher due to two relatively big catches of round sardinella.

Table 4. Guyana. Catch rates for main groups in bottom trawl stations standardized to kg/hour.

INNER SHELF

ST. NO.

DEP.

Demersal

Sharks

Shrimp

Pelagic

Squid

Other

637

13

5.00



61.00


57.80

639

14

79.10


72.80

218.40


19.60

640

15

155.20


48.00

265.60


50.40

641

19

105.60


28.00

129.60


19.00

643

25

18.40


2.40

12.80

0.80

137.00

644

25

6.80


1.80

5.00


16.30

645

41

1.80



0.60

4.20

3.40

650

41

202.00



27.00


69.60

651

35

242.00


0.60

9.40


95.00

65n2

31

9.10


5.60

15.60

0.60

37.20

653

22

7.40


8.60

19.20


36.70

654

17

92.80

24.40

3.84

85.50


55.50

655

23

254.80

55.80


442.60


27.20

656

25

2.20



103.60

6.40

3.40

657

18

6.00



411.40


7.80

658

41

39.60



465.60


18.90

663

45

82.00


1.00

17.60


58.50

664

38

42.00

2.00

4.20

31.40


27.92

665

21

555.80



49.50


34.10

666

20

59.40

12.00


269.20


81.00

667

34

5.40

2.40


77.20

0.60

8.00

668

17

36.60


0.80

222.80


17.60

669

33

11.80

1.60

0.20

50.00


29.20

670

32

74.00

5.60


84.40


217.40

676

37

265.60

6.00


73.92


19.00

MEAN


94.42

4.39

7.11

125.96

0.50

45.90


OUTER SHELF

ST. NO.

DEP.

Demersal

Sharks

Shrimp

Pelagic

Squid

Other

646

59

96.60



942.20


55.80

647

81

16.00



396.80

1.60

113.60

648

61

41.44


0.30

16.20

0.90

15.70

649

50

17.60



7.80


69.40

660

62




0.20

3.80

1.10

661

76

0.20



0.50

4.80

9.00

662

56

3.42


4.60

2.56


23.04

672

77

70.60


1.40

10.80


40.60

673

56

45.70

4.80

6.00

3.30


115.50

677

69

25.36

2.40

2.20

0.40


56.56

678

65

17.85


0.15

18.15

3.90

13.50

MEAN


30.43

0.65

1.33

127.17

1.36

46.71


Table 5 presents the catch rates by families for demersal fish on the inner and outer parts of the shelf. The mean catch of snappers are less than half of the previous survey for the inner shelf, while the mean rate of the grunts have increased manyfold.

Table 6 presents the catch rates analysed by families of pelagic fish. The mean rates for the various groups are approximately as in the previous surveys, but with a higher rate of sardines at outer shelf. This was due to two catches of round sardinella S. aurita within a small area.

Annex IV shows pooled length distributions of the most common species.

Venezuela.

Fishing covered the inshore fish assemblage, shrimp at intermediate depths at night and some trials for deep water shrimp in the slope down to 800 m. Record of the fishing stations are shown in Annex II from st. 679 to 695. Table 7 shows the standardized catch rates by the broad groups for all hauls including the deep water slope. Catch rates for all groups have dropped considerably since the previous survey. The decline might be caused by fish migration due to a heavy outflow of freshwater on the inner shelf.

Table 5. Guyana. Catch rates by families for demersal fish, kg/hour.

INNER SHELF

ST. NO.

DEP.

Catfish

Croakers

Grunts

Groupers

Snappers

Other.

637

13

4.60

5.00




114.20

639

14

16.80

79.10




294.00

640

15

36.80

155.20




327.20

641

19

15.00

105.60




161.60

643

25



1.20

13.60

3.60

153.00

644

25


3.40


3.40


23.10

645

41




0.40

1.40

8.20

646

59





96.60

998.00

650

41



127.00

3.00

72.00

96.60

651

35



188.40


53.60

105.00

652

31


5.40

0.60

2.10

1.00

59.00

653

22


2.80

3.80

0.80


64.50

654

17

7.00

92.80




162.24

655

23

9.20

254.80




516.40

656

25


1.00


1.20


113.40

657

18


6.00




419.20

663

45



16.50

7.00

58.50

77.10

664

38


42.00




65.52

665

21

7.70

213.20

332.20

4.40

6.00

75.90

666

20


55.80

3.60



362.20

667

34


5.40




88.20

66S

17

2.40

36.60




238.80

669

33


5.00



6.80

81.00

670

32





74.00

307.40

676

37

2.40

262.00

3.60



96.52

MEAN


4.08

53.24

27.08

1.44

14.94

200.33


OUTER SHELF

ST. NO.

DEP.

Catfish

Croakers

Grunts

Groupers

Snappers

Other

646

59





96.60

998.00

647

81





16.00

512.00

648

61




0.24

41.20

33.10

649

50




1.60

16.00

77.20

660

62






5.10

661

76





0.20

14.30

662

56


0.90

0.52


2.00

30.20

672

77


3.20

4.00

2.40

61.00

52.80

673

56


27.60

1.20

6.00

10.90

129.60

677

69


12.80

0.40

8.16

4.00

61.56

678

65


1.50



16.35

35.70

MEAN



4.18

0.56

1.67

24.02

177.23


Four deep water hauls were carried out to further test the catch rates for deep water shrimp. Maximum catch was 18 kg/hour.

At intermediate depths on the shelf shrimp catches at night ranged from 3 to 8 kg/hour as also found during the previous survey.

Table 8 shows the catch rates for demersal fish in the shelf hauls and Table 9 shows the catch rates for pelagic fish by families. For all groups the catch rates are considerably lower than in the previous surveys.

Annex V shows the length distributions of some of the most common species.

Table 6. Guyana. Catch rates by families of pelagic fish in pelagic and bottom trawl hauls, kg/hour.

INNER SHELF

ST. NO.

DEP.

Sardines

Anchovies

Carangids

Scombrids

Barracudas

Other

637

13


23.80

8.00

29.20


62.80

639

14

36.40

120.40




233.10

640

15

105.60

100.80

8.00



304.80

641

19

10.00

6.00

1.60



264.60

642


37.04

102.86

1.37


3.09

63.60

643

25

2.60

6.60

2.00


1.60

158.60

644

25

3.00


2.00



24.90

645

41



0.60



9.40

650

41

1.00


26.00



271.60

651

35



3.00

6.40


337.60

652

31

3.00


12.00


0.60

52.50

653

22



7.40

3.80

8.00

52.70

654

17

0.56

70.34

4.20



186.94

655

23

220.60

72.00

60.00

30.00


397.80

656

25

5.00


85.80

9.60

3.20

12.00

657

18

83.20


172.80

49.80

105.60

13.80

658

41

2.80


382.20

80.60


58.50

663

45

1.00



16.60


141.50

664

38

23.40


6.40


1.60

76.12

665

21

7.70

4.40

26.40

4.40


596.50

666

20

89.40

34.20

36.00

48.00

61.60

152.40

667

34

1.20


26.80

6.00

42.80

16.80

668

17

122.80

49.60

10.40

5.60

18.40

71.00

669

33

2.40


23.60

8.40

12.00

46.40

670

32

0.40


47.40

25.00

10.40

298.20

675


37.80

172.20

74.20



1090.40

676

37

27.36

10.56




326.60

MEAN


30.53

28.66

38.08

11.98

9.96

197.08


OUTER SHELF

ST. NO.

DEP.

Sardines

Anchovies

Carangids

Scombrids

Barracudas

Other

646

59

894.40


47.80



152.40

647

81

128.00


268.80



131.20

648

61

0.80


4.40

5.00

6.00

58.34

649

50



3.60

4.20


87.00

660

62



0.20



4.90

661

76



0.50



14.00

662

56

1.80


0.76



31.06

672

77



0.40

10.40


112.60

673

56

0.90


1.20



173.20

677

69






86.32

678

65



3.75

6.90

6.00

36.90

MEAN


93.26


30.13

2.41

1.09

80.77


Table 7. Venezuela. Catch rates for main groups in bottom trawl stations standardized to kg/hour.

ST. NO.

DEP.

Demersal

Sharks

Shrimp

Squid

Pelagic

Other

679

55

9.68

6.00

3.80

2.80

47.40

28.84

680

33





10.80


682

794


1.19

5.38



34.08

683

691


3.30

12.50

1.80

2.10

43.98

684

606


0.30

17.70

5.70

2.10

49.50

685

492


0.20

3.00

2.40

6.00

36.50

686

61

70.20

3.00

8.00


0.60

51.90

687

50

36.48

0.40

3.60


39.60

8.00

688

42

48.00

0.30



3.00

4.80

689

43

127.20


3.80



7.60

690

18

2.00

3.20


0.20

51.70

13.90

692

57

3.40

3.00

0.20

2.00

15.20

6.30

693

43

24.60




5.70

0.60

694

32

72.60

1.40



77.70

2.50

MEAN


29.85

1.59

4.16

1.06

21.05

21.16


Figure 1. Course tracks, fishing stations and hydrographic profiles.

Table 8. Venezuela. Catch rates by families for demersal fish, kg/hour.

ST. NO.

DEP.

Catfish

Croakers

Grunts

Groupers

Snappers

Other

679

55


4.40

0.08

0.40

4.80

88.84

680

33






10.80

686

61


5.40

4.20

6.00

54.60

63.50

687

50


38.36


0.12


51.60

688

42


48.00




8.10

689

43


127.20




11.40

690

18


2.00




69.00

692

57


1.20


0.40

1.80

26.70

693

43


24.60




6.30

694

32


69.60

3.00



81.60

MEAN


0.62

34.26

0.73

0.69

6.12

45.24

Table 9. Venezuela. Catch rates by families of pelagic fish in pelagic and bottom trawl hauls, kg/hour.

ST. NO.

DEP.

Anchovies

Sardines

Carangids

Scombrids

Hairtails

Other

679

55


13.80

14.80

2.80

10.80

56.32

680

33



10.80




606

61





0.60

133.10

687

50


10.80

0.40


26.00

52.88

688

42





3.00

53.10

689

43






138.60

690

18

3.20

5.30


11.00

32.20

19.30

692

57


0.80

2.60

3.20

1.80

21.70

693

43


0.90


1.80


28.20

694

32

2.80

34.50

24.40


16.00

76.50

MEAN


1.32

6.97

6.98

2.28

9.16

60.95


Figure 2. a) Hydrographic profiles. WEST OF MARONI RIVER 12.8 1988

Figure 2. b) Hydrographic profiles. EAST OF DEMARARA RIVER 17.8.1988

Figure 2. c) Hydrographic profiles. ORINOCO 20-21.8 1988

Figure 3. Distribution of pelagic fish from acoustic system.


Previous Page Top of Page Next Page