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 trawl stations are shown in Annex II, nos. 919-952 and 960-965. 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. Mean catch rates are highest on the inner shelf for demersal fish. Catch rates for pelagic fish in a bottom trawl is not very meaningful, but the indication is a higher availability on the inner shelf. There is some variation between surveys of the mean catch rates for the various groups and this will be analysed in the final report. It seems evident, however, that the highest rates for squid were obtained in the May Survey. In general only low catch rates of shrimps were obtained. The catch rates for the deep sea scarlet shrimp at st 924 and 925 were 11 kg/hr and 3.5 kg/hr respectively. Table 2 presents an analysis of catch rates by families of demersal fish for the two parts of the shelf. The predominance of catfish, croakers and grunts on the inner shelf and of snapper on the outer part is evident. The lane snapper Lutjanus synagris represented about 50 % of the total snapper catch and dominated in the 25 - 40 m depth zone.

The red snapper Lutjanus purpureus usually found on the outer shelf only was less common than previously. The species in the inshore assemblage were largely the same as those found previously: king weakfish, Macrodon ancylodon dominated among the croakers and the corocoro Orthopristes ruber among the grunts.

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
919	29	0.4		0.1	19.3	25.0	3.5
920	29	27.8		3.6	1525.4		65.2
921	45	11.9	7.6		79.9	2.4	6.9
926	39	239.6	3.6		330.2	2.6	166.1
927	34	2035.0			323.0		81.8
928	28	65.2	23.6		1350.0		3.8
938	33	44.0		4.7	3.7	0.6	54.0
939	39	12.2	5.8	1.4	9.2	3.2	85.4
940	31	64.5	27.6		2116.8		12.4
941	17	179.0	2.2	0.8	267.9		44.8
942	24	142.0	31.8		65.9		5.4
943	26	5.8	0.8		25.1	2.4	3.0
944	22	54.1	4.2	2.1	472.4		96.2
945	25				65.0	0.3	52.2
946	20	36.8		5.6	3114	5.1	122.2
947	20	68.1	9.2	3.8	378.3	4.8	58.8
948	19	660.0	2.4	6.5	150.4		137.6
949	30	34.3	1.2	0.1	7.5	3.9	66.7
961	22	661.0		4.3	744.6	22.3	185.4
962	24	641.2			34.3	13.5	67.5
963	28	2.0	1.0		8.6	30.0	10.0
964	24	8.1	10.0		29.4	18.8	66.4
965	17	161.9,		20.2	100.7	1.4	141.5
MEAN		224.1	5.7	2.3	366.0	5.9	66.8

OUTER SHELF

ST. NO.	DEP.	Demersal	Sharks	Shrimp	Pelagic	Squid	Other
922	67	79.0	4.0		85.7	0.4	22.4
923	90	138.4	9.0		204.7	1.4	67.4
924	705			26.5		1.5	25.2
925	510		4.6	19.1	8.4	3.9	28.9
929	78	106.6	20.2		296.4		30.4
930	84	42.9	11.0		159.8	0.6	8.6
931	81	127.3	1.8.		30.6	0.6	50.2
932	72	100.0	16.6		34.1		22.0
933	92	367.5			0.3	0.6	6.0
934	83	220.8			659.6		49.6
935	70	7.9			10.4	1.4	10.1
936	49	43.7	2.7	4.3	15.9	1.3	68.4
937	44	13.3		3.3	2.5	2.4	70.1
950	46	225.6		1.4	12.7		97.2
951	49	206.2		0.1	29.1	0.6	104.1
952	62	159.8			23.4.	7.0	21.1
MEAN		114.9	4.3	3.4	98.4	1.3	42.6

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

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

INNER SHELF

ST. NO.	DEP.	Catfish	Croakers	Grunts	Groupers	Snappers	Other
919	29				0.4		48.0
920	29		21.6	4.2	2.0		1594.2
921	45				0.1	11.8	96.8
926	39			26.2		213.4	502.5
927	34			1382.2		652.8	404.8
928	28		10.4	2.0		52.8	1377.4
938	33			31.8	3.2	9.0	63.0
939	39			0.2	4.2	7.8	105.0
940	31		12.1			52.4	2156.8
941	17	40.6	137.7	0.7			315.7
942	24			30.0		112.0	103.1
943	26		0.4	1.4		4.0	31.3
944	22	20.0	32.9	1.2			574.9
945	25						117.5
946	20	8.4	28.4				444.3
947	20	3.3	64.8				454.9
948	19	15.6	623.6	20.8			296.9
949	30			6.9	7.4	19.9	79.5
961	22	10.8	648.8	1.4			956.7
962	24			297.0	0.7	343.5	115.3
963	28			0.3	1.2	0.4	49.6
964	24				2.8	5.3	124.7
965	17	53.4	108.5				263.8
MEAN		6.6	73.4	78.5	0.9	64.5	446.8

OUTER SHELF

ST. NO.	DEP.	Catfish	Croakers	Grunts	Groupers	Snappers	Other
922	67			0.6		70.4	112.5
923	90			16.0		122.4	282.5
924	705						61.6
925	510						58.1
929	78					106.6	347.0
930	84		1.8			41.0	180.1
931	81				0.1	127.2	83.3
932	72					100.0	72.7
933	92			0.3		367.2	6.9
934	83					220.8	709.2
935	70			0.0	0.0	7.8	21.9
936	49		6.5	16.3	5.5	15.3	92.8
937	44			6.6	0.4	6.3	78.3
950	46			135.7	1.5	88.4	111.4
951	49		2.1	120.3	4.8	79.0	133.9
952	82			7.0		152.8	51.5
MEAN			0.6	18.9	0.7	94.5	150.2

There is as previously an absence of anchovies on the outer shelf and also sardines are scarce here, the family being represented only by Atlantic sardinella, Sardinella aurita. Most of the carangid catches in deep water consisted of rough scad, Trachurus lathami with some Selene and Hemicaranx.

On the inner shelf the clupeid component of the catches consisted mostly of juveniles of various species, but dominated by dogtooth herring, Chirocentrodon bleekerianus and pellona, Pellona harroweri and with some sardinella and thread herring.

The bumper Chloroscombrus chrysurus was common inshore with some lookdowns and jacks.

The catch rates for Spanish mackerels were relatively high with the king mackerel Scomberomorus cavalla as the most common form. Both species of barracudas occurred, but Sphyraena guachancho dominated.

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

INNER SHELF

ST. NO.	DEP.	Clupeids	Anchovies	Carangids	Scombrids	Barracudas	Other
919	29	10.6	0.3	4.6		3.6	29.1
920	29	1440.0	62.4		17.0	3.0	99.6
921	45	0.6		57.0	18.4	3.9	28.8
926	39	9.1		310.7	3.4	7.0	411.9
927	34			153.6	28.6	83.2	2174.4
928	28	644.0	644.0	7.8	52.6		94.2
930	33			2.2	1.5		103.3
939	39	0.4		8.8			100.0
940	31	443.4	1311.6	101.2	103.8	142.8	118.5
941	17	90.3	73.1	62.5		1.4	267.4
942	24	0.7		18.6	33.0	13.6	179.2
943	26		0.7	10.1	12.0	1.2	13.1
944	22	243.4	123.6	59.6	41.0		161.4
945	25	0.2		12.0	44.4	7.9	53.1
946	20	42.9	188.7	14.2	22.4		212.9
947	20	87.4	212.3	15.8	25.0		182.5
948	19	70.2	5.2.	20.4	39.0		822.1
949	30		2.0	4.7		0.8	106.3
960	8	182.0	53.6	1.6	7.6		32.2
961	22	354.2	21.6	49.2	56.8		1135.8
962	24			8.2	9.5		738.7
963	28	0.4		8.2			43.0
964	24	8.7	1.9	11.6	7.2		103.4
965	17	12.8	12.2				400.7
MEAN		151.7	113.0.	39.2	21.8	11.1	317.5

OUTER SHELF

ST. NO.	DEP.	Clupeids	Anchovies	Carangids	Scombrids	Barracudas	Other
922	67	4.4		75.3	0.8	4.4	106.6
923	90			201.3	3.4		216.2
929	78			283.2	8.4	4.8	157.2
930	84	5.1		128.2	18.1	8.2	63.3
931	81	1.0		24.2	5.4		180.1
932	72			20.4	3.2	10.5	138.6
933	92			0.3			374.1
934	83	64.0		582.4	6.8		276.8
935	70			10.4			19.4
936	49	0.1		13.1		2.7	120.6
937	44	0.1		2.4			89.2
950	46	1.8		10.9			324.3
951	49			27.3		1.8	311.0
952	82	6.3		9.1	0.0		187.9
MEAN		5.9		99.1	3.8	2.3	183.2

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

Guyana.

For records of the fishing stations reference is made to Annex II, stations 953-959 and 966-1003. Table 4 shows the standardized catch rates for the broad groups and for the inner and outer shelf (shallower resp deeper than 40 m). All groups show low catch rates offshore. For the inner shelf the catch rates for demersal fish are about the same as in Surveys II and III, for sharks somewhat higher. For shrimp the rates were overall low, the relatively higher rates in a few of the shallow water hauls derive from Xiphopenaeus. kroyeri and the catch at station 980 at 690 m depth included 7 kg of the deep water scarlet shrimp, Pleisopenaeus edwardsianus. An attempt to make more tests for this shrimp further west along the slope had to be aborted due to rough bottom. The shelf squid was more abundant than in Survey III, but consisted mostly of juveniles.

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
958	36	2.2	1.0		14.3	26.2	14.3
959	32	178.9			20.5	96.8	66.7
966	25	4.2		0.2	94.8	8.6	32.0
967	20	102.9.		0.4	154.6		5.6
968	23	419.1	1.0	2.5	75.8		6.4
971	17	173.0	98.6	0.7	108.9		35.0
972	22	48.4			32.4	4.2	26.1
973	24	7.8	1.8		61.1	3.4	12.6
974	23	18.5	9.2		81.6		5.4
975	19	149.2			177.8		39.3
976	24	1.1			13.4	16.4	0.7
977	34	3.3		0.2		28.4	2.1
982	39	0.3			13.0	1.7	57.9
983	23	3.6			11.1	8.2	0.8
984	23	3.0	3.5		183.9.	8.9	5.9
985	15	227.2	0.8	29,6	129.5		76.6
986	23	1.6	10.1		254.2	3.6	2.4
987	16	167.3	29.4	3.4	151.6		18.5
988	23	7.9	3.4		16.9	6.8	13.3
989	33	17.5		4.3	16.2	0.9	22.0
992	40	1.4		0.1	32.2	6.0	8.5
993	19	290.1	9.6	4.4	203.4		46.9
994	18	60.6	8.4		496.2		16.8
995	15	119.4		2.0	49.7		94.8
996	35	1.0	55.8		132.4	6.8	22.0
997	39	27.1	9.0		46.9	0.1	37.1
1002	15	341.7	24.3	29.3	255.2		113.8
1003	29	114.6	43.8	0.5	360.2	0.6	53.4
MEAN		89.0	11.0	2.7	113.8	8.1	29.9

OUTER SHELF

ST. NO.	DEP.	Demersal	Sharks	Shrimp	Pelagic	Squid	Other
953	62	92.0				5.4	93.8
954	88	54.9				0.4	4.9
955	85	142.1			4.0	2.4	10.0
956	54	8.2			20.0	16.8	52.0
957	43	49.7				16.8	43.2
978	59	10.9			12.8	13.4	85.0
979	88	222.0		1.3	445.9	2.6	63.6
980	691			12.0			31.3
981	53	137.8		0.4	12.8		85.6
990	50	101.5		1.3,	3.6	0.5	106.1
991	55				51.6	11.4	1.2
1000	73	97.6		0.6	9.6	1.0	42.0
1001	60	2.5	7.4		130.4	0.9	6.5
MEAN		70.7	0.5	1.2	53.1	5.5	48.1

Table 5 presents the catch rates by families for demersal fish on the inner and outer parts of the shelf. As previously catfish and croakers dominate the inner - and snappers with some grunts the outer shelf. The king weakfish Macrodon ancylodon dominate the croakers with some green - Cynoscion virescens and acoupa weakfish Cynoscion acoupa. No high catches of snappers were made and the most common form was lane snapper Lutjanus synagris.

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

INNER SHELF

ST. NO.	DEP.	Catfish	croakers	Grunts	Groupers	Snappers	Other
958	36		0.4	1.0	0.8		55.8
959	32			156.6	6.0	16.3	184.0
966	25				1.4	2.8	135.7
967	20	13.0	89.9				160.6
968	23		277.9	140.0		1.2	85.7
971	17		152.2	17.4	3.2	0.2	243.3
972	22		1.3	5.3	7.2	34.6	62.7
973	24				5.6	2.2	78.9
974	23		3.6	14.4	0.2	0.3	96.2
975	19		149.2				217.1
976	24				0.3	0.8	30.5
977	34			0.2	2.4	0.6	30.8
982	39		0.3				72.6
983	23				3.2	0.4	20.2
984	23		1.8		0.6	0.5	202.3
985	15	37.2	190.0				236.6
986	23		1.6				270.3
987	16	58.4	108.9				202.9
988	23				0.7	7.2	40.4
989	33		14.0		1.7	1.8	43.5
992	40				0.4	1.0	46.8
993	19	27.4	255.9	6.7			264.3
994	18		52.8	7.8			521.4
995	15	8.7	109.7	1.0			146.5
996	35					1.0	217.0
997	39		2.6		1.2	23.3	93.1
1002	15	72.2	269.4				422.8
1003	29	3.4	111.2				458.5
MEAN		7.8	64.0	12.5	1.2	3.3	165.7

OUTER SHELF

ST. NO.	DEP.	Catfish	Croakers	Grunts	Groupers	Snappers	Other
953	62		0.1	28.8	0.1	62.9	99.2
954	88			6.0		48.9	5.3
955	85			1.3		140.8	16.4
956	54				0.0	8.2	88.8
957	43			21.6	1.0	27.1	60.0
978	59			0.1	1.6	9.2	111.2
979	88			26.0		196.0	513.4
980	691						43.3
981	53		0.8	54.4	4.0	78.6	98.8
990	50		0.7	56.6	5.9	38.2	111.5
991	55						64.2
1000	73			4.8	1.2	91.6	53.3
1001	60					2.5	145.3
MEAN			0.1	15.3	1.0	54.1	108.5

Table 6 presents the catch rates analysed by families of pelagic fish including hauls with mid water trawl. The Clupeids represent mostly juvenile fish, but the catch at st. 979 offshore was adult sardinella. The bumper was the most common form of the Carangids with bluntnose jack Hemicaranx amblyrhynchus and moonfish Selene setapinnis next. Spanish mackerels occurred in nearly all hauls and gave relatively high catch rates dominated by Scomberomorus brasiliensis. Barracudas were common inshore in the eastern parts represented mostly by the species Sphyraena guachancho.

Annex IV shows pooled length distributions 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.	Clupeids	Anchovies	Carangids	Scombrids	Barracudas	Other
958	36	3.6	2.6	7.0			44.8
959	32	0.6		19.9.			342.4
966	25	20.9	56.9	15.8			46.2
967	20	64.4	43.6	14.4	15.2		125.9
968	23	24.9.		22.3	24.6	4.0	429.0
969	10	99.4	201.6	14.3	6.4		44.3
970	13	73.8	100.4	32.8			2.7
971	17	22.9	9.2.	3.0	19.0	16.0	346.1
972	22	0.2			26.2		84.7
973	24			56.1	5.0		25.6
974	23	0.0		35.2	0.8	36.8	33.1
975	19	127.0	18.7	15.6	3.9.	4.1	196.9.
976	24	3.2.	0.4	2.1	7.6		18.2
977	34						34.1
982	39			13.0			59.9
983	23			0.9	10.2		12.7
984	23	14.2	8.5	106.3	54.3	0.3	21.4
985	15	22.8	15.4.	8.2	19.0		398.3
986	23	2.5		95.4	52.2	104.0	17.7
987	16	26.0	16.0	12.0	16.8		298.6
988	23			2.7	13.2	1.0	31.4
989	33	7.0		7.0		2.2	44.8
992	40			24.0	4.4	3.8.	16.0
993	19	11.2	14.2	21.0	17.4		490.5.
994	18	30.6	21.6	75.0	225.0	144.0	85.8
995	15	13.8	3.0	11.1	3.2		234.8
996	35	8.0		25.5	12.4	86.5	85.6
997	39	0.4		14.0	12.8	19.0	74.0
998		457.1	225.0	21.9	40.4	90.0	41.5
999		68.4	182.4	25.4	70.2	5.8	97.0
1002	15	152.4	21.0	18.2	7.6		565.2
1003	29	136.7.	8.3	175.4	8.2	6.00	238.5
MEAN		43.5	29.6	28.0	21.3	16.3	143.4

OUTER SHELF

ST. NO.	DEP.	Clupeids	Anchovies	Carangids	Scombrids	Barracudas	Other
953	62						191.2
954	88						60.3
955	85			4.0			154.5
956	54			13.8	6.2		77.1
957	43						109.7
978	59	2.8		10.0			109.4
979	08	410.8		35.1			289.5
981	53	1.2		11.6			223.8
990	50	1.4		2.2			209.4
991	55			51.0			13.2
1000	73			4.0	3.0	2.6	141.3
1001	60	0.4		102.8	17.0	10.2	17.4
MEAN		34.7		19.5	2.1	1.0	133.0

Venezuela.

Fishing covered the inshore fish assemblage, shrimp at intermediate depths at night and some trials for deep water shrimp in the slope at abt. 700 m. Record of the fishing stations are shown in Annex II from st. 1004 to st. 1019. Table 7 shows the standardized catch rates by the broad groups for all bottom hauls including the deep water slope. Catch rates for demersal fish and sharks show much the same ranges as previously. Catch rates for shrimp were generally low at mid shelf, 3-9 kg/hr for pink shrimp and few shrimp vessels were seen. The two deep hauls gave 4 and 6 kg/hr of scarlet deep sea shrimp, Plesiopenaeus edwardsianus.

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
1004	63	8.1	6.4	0.6	6.2	57.4	13.0
1005	16	621.4	21.0	2.0		794.5	188.1
1006	14	276.6	8.2	35.5		61.5	211.2
1007	58	5.2	1.0	8.0	3.2	3.6	22.6
1008	70	41.2	4.0	7.1	2.0	0.9	56.3.
1009	62	4.5	2.4	13.5	1.5	5.7	17.5.
1010	75	80.5		5.2			77.9
1011	712			19.1	22.5	1.4	71.5
1012	723			10.0	6.4		121.0
1013	67
1014	63	40.5	3.0	26.9	2.0	0.6	47.4
1015	33	48.3	59.8			991.8	99.8
1017	45	37.6	5.6			199.0	69.4
1018	25	123.2	17.0	0.4		127.9	10.0
1019	36	25.0	7.7		12.7	61.5	31.0.
MEAN		87.4	9.0	8.5	3.7	153.7	69.1.

Table 8 shows the catch rates for demersal fish in the shelf hauls. There were a few relatively large catches of croakers in shallow water dominated by king weakfish. Snappers were scarce.

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

ST. NO.	DEP.	Catfish	Croakers	Grunts	Groupers	Snappers	Other
1004	63	0.4	2.9		0.0	4.8	83.6
1005	16	60.1	551.3	10.0			1005.6
1006	14	42.5	234.1				316.4
1007	58		1.2	0.4	3.2	0.4	38.5
1008	70			1.7	5.2	34.3	70.5
1009	62		2.6		1.3	0.6	40.6
1010	75			2.8	1.5	76.2	83.1
1011	712						114.5
1012	723						137.4
1013	67
1014	63				8.1	32.4	79.9
1015	33	5.8	42.5				1151.4
1017	45	18.8	6.4			12.4	274.0
1018	25	9.6	113.6				155.3
1019	36		25.0				113.0
MEAN		9.1	65.3	1.0	1.2	10.7	244.2

Table 9 shows the catch rates for pelagic fish by families for the shelf hauls. Scaled herring and pellona dominated the Clupeids, Anchoviella species the anchovies and lookdowns the Carangids. Spanish mackerels and barracudas were abundant.

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

Table 9. VENEZUELA. Catch rates by families for Pelagic fish in Pelagic and bottom trawl hauls, kg/hour.

ST. NO.	DEP.	Clupeids	Anchovies	Carangids	Scombrids	Barracudas	Other
1004	63			37.8	3.8	14.2	35.9
1005	16	335.9	291.4	48.7	83.0	32.4	835.5
1006	14	16.9	11.8		2.4		561.9
1007	58	0.0		2.8			40.6
1008	70			0.9			110.6
1009	62			4.7		1.0	39.4
1010	75						163.6
1013	67
1014	63					0.6	119.8
1015	33	127.2	674.8	132.2	13.8	30.2	221.5
1016	13		2.4	3.6	103.8	0.8	12.0
1017	45	158.0		8.4		22.6	122.6
1018	25	43.5	23.6	6.2	9.0		196.2
1019	36	39.4	7.6	10.6		0.7	79.7
MEAN		51.5	72.2	18.2	15.4	7.3	181.4

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