5. Results of 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 commercial fishing or special fishing surveys.

Oriente.

The fish on the shelf between Bocas de Dragon and Cabo Codera can roughly be identified as two assemblages: that belonging to the inner part of the shelf, inside the Testigos Archipelago and the Margarita Island and on the coastal side of the Cariaco Trench in which pelagic fish, sardines and anchovies dominate and catfish and croakers are the most common groups of the demersals; and on the other hand the assemblage found over the outer parts of the shelf outside the Testigos and Margarita Island and westwards past the Tortuga Island where the pelagic fish is represented mostly by carangids, but with some sardinella and the demersal fish is dominated by snappers and grunts with some breams, groupers and glasseyes. This grouping is used in the following description of the composition and catch rates of the fishing experiments. The complete record of all hauls made are shown in Annex II, Stations 1078 to 1127 and the position of the stations can be seen in Figure 1.

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

INNER

ST. NO.	DEP.	Demersal	Pelagic	Sharks	Squids	Shrimp	Other
1082	44	80.6	66.3	2.4	4.7	5.2	68.1
1084	53	422.1	9.0	3.6		2.0	54.2
1086	12	696.0	876.4
1087	20
1088	35	7.1	57.2		13.6	0.1	14.0
1107	35	16.4	37.4		8.8	8.4	88.2
MEAN		203.7	174.3	1.0	4.5	2.6	37.4

OUTER

ST. NO.	DEP.	Demersal	Pelagic	Sharks	Squids	Shrimp	Other
1079	71	386.6	3.0	1.0			136.2
1080	32	8.6	98.8				243.7
1081	30	677.5	194.8	5.4			429.6
1089	28	749.7	626.4		19.2		35.9
1090	32	13.2	1.8		89.2		31.6
1091	32	36.0	11.4	4.2	3.2	0.2	58.0
1092	448			9.9	5.9	41.9	60.9
1093	316			15.7	0.4	32.6	245.1
1094	298	18.8	2.0	12.5	1.1	32.2	176.5
1095	74	124.9	2.1	28.8	17.5	0.3	32.2
1096	46	71.0	3.5	14.0	68.5		40.3
1097	31	0.1	0.1		31.0		237.4
1098	29	4.7			15.6		129.6
1099	34	32.7	2.0		50.6	0.5	56.0
1100	49	946.4	50.6		2.4		228.8
1101	402			9.9	0.2	10.2	118.6
1102	506			1.7	2.9	3.7	75.9
1103	413			28.0		10.3	365.2
1104	46	49.8	4.8	10.0	4.8		135.4
1105	24	2.6	3.6		3.0		329.3
1106	86	565.9	29.4				461.6
1113	113	27.0	2557.4				500.6
1114	92	103.9	1.7				155.5
1115	152	242.0	259.0				66.3
1116	78	7.3			0.3		65.0
1117	31	51.6			1.2		497.2
1118	90	95.2	72.4	3.0		2.2	46.5
1119	401			22.3	3.9	42.0	101.3
1120	503			0.3	1.4	7.6	58.3
1121	86	46.4	1.8		0.3		35.0
1122	39						2.0
1123	71				0.5		30.8
1124	48	57.0	188.4		0.2		204.0
1125	70	0.5			0.3		25.4
1126	70	39.5	69.2		0.8		22.2
1127	65	8.2	9.2	8.4	0.0		47.3
MEAN		121.3	116.5	4.8	9.0	5.1	152.4

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. For the inner shelf only few hauls were made with the bottom trawl, the main effort being allocated to the outer part. Here the ranges and means of catch rates for the main groups of pelagic and demersal fish indicate a reduced availability as compared with previous surveys especially in the western part. For the shelf squids the catch rates in the area between Los Testigos and Margarita Island had increased as compared with Survey 3. By far the main part of the catches were Loligo plei, the other species Loligo pealei represented only a few per cent. Eight hauls were made testing the availability of deep water shrimp between 300 and 500 m. Catches ranged up to 40 kg/hour, with medium - or smaller sized species dominating such as Aristaemorpha folicea and Penaeopsis serrata, but with rates up to 8 kg/hour of the larger sized Pleoticus robustus.

Table 2. ORIENTE. Catch rates by families for demersal fish in bottom trawl, kg/hour.

INNER

ST. NO.	DEP.	Catfish	Croakers	Grunts	Snappers	Groupers	Other
1082	44	8.7	61.6	1.5	0.3	8.4	146.7
1084	53	374.4	40.4			7.3	68.8
1086	12			690.4		5.6	876.4
1087	20
1088	35	0.8	4.8	0.3	0.9	0.2	84.9
1107	35			1.0		15.4	142.8
MEAN		63.9	17.8	115.5	0.2	6.1	219.9

OUTER

ST. NO.	DEP.	Catfish	Croakers	Grunts	Snappers	Groupers	Other
1079	71			38.2	340.0	8.4	140.2
1080	32			7,8		0.7	342.5
1081	30			590.3	87.2		629.8
1089	23			743.8		0.9	681.5
1090	32			0.6	12.4	0.2	122.7
1091	32		16.9	0.4	10.3	8.4	77.0
1092	448						118.7.
1093	316						294.0
1094	298		4.8			14.0	224.3
1095	74				117.6	7.3	31.0
1096	48				67.8	3.2	126.3
1097	31					0.1	268.5
1098	29			1.8		2.9	145.2
1099	34			3.1	27.2	2.4	109.2
1100	49		2.4	384.2	264.9	294.8	281.9
1101	402						138.9
1102	506						84.3
1103	413						403.6
1104	46				44.1	5.7	155.0
1105	24			0.9	1.1	0.6	335.9
1106	86		1.8	43.2	520.2	0.7	491.0
1113	113				27.0		3058.0
1114	92				99.4	4.4	157.21
1115	152				242,0		325.31
1116	78			0.8	5.9	0.6	65.3
1117	31			2.2	33,0	16.4	498.4
1118	90			51.2	44.0		124.1
1119	401						169.5
1120	503						67.7
1121	86			0.2.	31.8	14.3	37.3
1122	39						2.0
1123	71						31.3
1124	48			7.8	18.1	31.0	392.6
1125	70				0.5		25.7
1126	70			10.0	29.4	0.1	92.2
1127	65				7.8	0.4	64.9
MEAN			0.7	52.5	56.4	11.61	287.9

Table 2 shows the catch rates by families for the demersal fish on the inner and outer shelf parts. Snappers and grunts with some groupers dominate the outer part. Among the snappers, the small sized Pristipomoides macropthalmus represented about 50 % and Rhomboplites aurorubens about 20 % and the larger species Lutjanus analis, L. purpureus and L. vivanus some 15 %. The grunts were predominantly Haemulon boschmae.

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

INNER

ST. NO.	DEP.	Sardines	Anchovies	Carangids	Scombrids	Barracudas	Other
1078	11	819.0	1.8	7.8			5.2
1082	44	56.8	0.1	2.4		6.9	161.1
1083	10	110.2	10.4			4.4	6.8
1084	53	7.2				1.8	481.9
1085	10	9.4	65.7			10.7	2.0
1086	12	868.0		8.4			696.0
1087	20
1088	35	51.6	5.6				34.8
1107	35			13.4		24.0	121.8
1108	9	20.9	318.0	0.1		12.8
1109	9	20.8		0.4	0.4		0.3
1110	11			0.2
1111	16	74.4	46.8				15.0
1112	15	7.0		7.5
MEAN		146.1.	32.0	2.8	0.03	4.3	108.9

OUTER

ST. NO.	DEP.	Sardines	Anchovies	Carangids	Scombrids	Barracudas	Other
1079	71			3.0			523.8
1080	32	98.3		0.5			252.3
1081	30	160.0		34.8			1112.5
1089	28	614.4		12.0.			804.8
1090	32			0.0		1.8	134.1
1091	32		0.2	1.6	3.0	6.6	101.6
1092	448						118.7
1093	316						294.0
1094	298			.2.0			241.1
1095	74			2.1			203.8
1096	48			3.5			193.8
1097	31			0.1			268.5
1098	29						149.9
1099	34			1.4		0.6	139.9
1100	49	43.2		5.0		2.4	1177.6
1101	402						138.9
1102	506						84.3
1103	413						403.6
1104	46			4.2	0.6		200.0
1105	24			3.6			334.9
1106	86			27.0		2.4	1027.6
1113	113	118.8.		2195.6	243.0		527.6
1114	92			1.7			259.4
1115	152	14.0		37.0	208.0		308.3
1116	78						72.6
1117	31						550.0
1118	90			69.2	3.2		146.9
1119	401						169.5
1120	503						67.7
1121	86			1.8			81.8
1122	39						2.0
1123	71						31.3
1124	48	146.4		42.0			261.2
1125	70						26.2
1126	70			69.2			62.5
1127	65			9.2			64.0
MEAN		33.2	0.0	70.1	12.7	0.3	292.7

Table 3 shows the catch rates for the different types of pelagic fish in the trawl stations from the inner and outer shelf. In addition to sardinella, the scaled herring Harengula jaguana was caught on some stations. Of the carangids Trachurus lathami was found in some abundance on the Tortuga Ridge together with some mackerel Scomber japonicus.

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

Western part from Cabo Codera to Peninsula de Guajira.

The complete records of the trawl hauls made in this area are shown in Annex 2, stations 1128 to 1179 and the positions are illustrated in Figure 1. As previously preliminary analyses are made of the data from the west coast to Peninsula de Paraguana and the Gulf of Venezuela separately. For the Western Coast the standardized catch rates by main groups are shown in Table 4. From previous surveys there is a general impression of low catch rates from this narrow shelf and this is confirmed also by this survey. Seven hauls were made in depths between 240 and 450 m testing for deep sea shrimp, but with only low catch rates. Squid catch rates were also generally low. Table 5 shows the standardized catch rates of demersal fish split by families where snappers dominate with highest catch rates at intermediate depths, 40 - 80 m. The most common forms were mutton snapper, Lutjanus analis with abt. 30 %, lane snapper Lutjanus synagris with abt. 25% and vermillion snapper Rhomboplites aurorubens with abt 15% of the total catch. The small catches of pelagic fish caught in this area, see Table 6 were dominated by carangids, mostly bumper and various species of lookdowns.

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

ST. NO.	DEP.	Pelagic	Demersal	Squid	Sharks	Shrimp	Other
1127	55	9.2	8.2	0.0	8.4		47.3
1129	359			6.4	1.2	0.6	91.3
1130	399	1.3		23.5	0.2	8.2	65.4
1131	103	66.2	34.4				21.1
1132	58	0.1	23.1	0.2			41.1
1133	38	19.0	30.2	1.7		0.0	56.5
1134	104	3.4	23.1	0.4	13.4	1.0	59.5
1135	240	6.0	36.5	5.2	4.0	3.6	51.1
1136	242	27.6	25.3	6.4	7.4	0.0	87.2
1137	68	1.5	8.2	7.5			45.4
1138	63	2.1	198.3	4.0		0.1	62.9
1139	50	156.3	43.5	0.3			163.1
1140	33	99.0	90.4	1.3		0.2	78.8
1142	485	3.6		22.5	9.0	8.4	60.4
1143	377	1.3		4.7	1.5	2.3	73.6
1144	61	31.5	46.8	2.5		0.3	34.6
1145	47	90.0	43.6	4.2	8.8		142.2
1146	59	18.5	83.9	2.5			39.2
1147	19	11.1					0.0
1148	75	11.1	182.3	5.7	31.2		121.3
1149	41	122.9	59.3	3.6		0.3	88.2
1151	449	3.0		11.3	0.1	12.4	43.2
1152	82		125.6	2.0	3.2	0.1	51.5
1153	25	1.2	20.4	1.0			11.4
1154	42	10.6	183.6	0.9			31.3
1155	93	22.9	30.4	25.7		0.2	54.9
1156	43	37.9	11.3.	13.0			40.7
MEAN		28.0	48.5	5.8	3.2	1.4	61.6

Table 5. WESTERN PART. Catch rates by families for demersal fish in bottom trawl, kg/hour.

ST. NO.	DEP.	Croakers	Snappers	Grunts	Groupers	Glasseyes	Other
1127	65		7.8		0.4	0.2	64.7
1129	359						99.6
1130	399						99.3
1131	103		25.8		8.6	0.4	86.9
1132	58		17.5		0.8		46.2
1133	30		16.2	0.2	0.3	2.2	88.5
1134	104		18.0	3.0	0.3		79.7
1135	240		34.8		1.7		69.9
1136	242	4.8	21.0'		0.0		128.8.
1137	68		7.8		0.4	4.6	49.8
1138	63		143.4	17.6	7.5	0.9	98.0
1139	50		38.2		0.3	25.4	299.3
1140	33	28.0	62.3	0.2	0.1	2.8	176.3
1142	485						103.9
1143	377						83.5
1144	61		45.0	1.8	0.0	0.5	68.4
1145	47	2.8	40.8				245.3
1146	59		73.8		0.1	4.3	65.9
1147	19						11.2
1148	75		180.7	69.3	1.5	10.8	89.2
1149	41		58.6		0.7		215.1
1151	449						70.1
1152	82	0.1	123.0	2.2	0.7	18.8	37.6
1153	25		4.4				29.6
1154	42		142.9	1.0	0.7	2.1	79.5
1155	93	0.2	28.0		2.2		103.9
1156	43		10.4		1.4	2.4	89.3
MEAN		1.3.	40.7	3.5	1.0	2.8	99.2

Table 6. WESTERN PART. Catch rates by families for pelagic fish in bottom and pelagic trawl hauls, kg/hour.

ST. NO.	DEP.	Sardines	Hairtails	Carangids	Scombrids	Barracuda	Other
1127	65			9.2			64.0
1128	4	73.2		33.4		5.3	122.2
1131	103			66.2			55.5
1132	58			0.1			64.5
1133	38			13.0	4.0	2.0	88.5
1134	104			3.0	0.4		97.5
1135	240			6.0			100.4
1136	242		25.2	2.4			127.1
1137	68			1.5			61.1
1138	63			2.1			265.3
1139	50			87.3		69.0	206.9
1140	33	7.6	9.3.	33.3	13.0	35.6	170.8
1141	13			5.4		4.8	61.9
1144	61			31.5			84.2
1145	47			64.2	15.8	9.8	198.9
1146	59			15.3	3.2		125.6
1147	19				8.8	2.3.	0.0
1148	75			11.1			340.5
1149	41			80.7	6.4	35.8	151.5
1150	15	26.8	0.8	0.2	0.4		21.1
1152	82						182.5
1153	25			0.4		0.8	32.8
1154	42			10.6			215.8
1155	93			21.2	1.7		111.4
1156	43			29.5	0.0	7.6	66.4.
MEAN		4.3	1.4	21.1	2.1	6.9	120.6

In the Gulf of Venezuela the catch data have been analyzed for an inner and an outer part separately, with a dividing line from Punto Fijo westwards, see Table 7. In both parts the catch rates are markedly lower than those obtained in previous surveys both for the main groups of fish and for squids and shrimp. Among the demersal fish, see Table 8 it seems that in particular the snappers show a reduced availability, while all groups of pelagic fish, Table 9, have low rates.

Length compositions of pooled samples of the most common species are shown in Annex 3.

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

INNER PART

ST. NO.	DEP.	Pelagic	Demersal	Squid	Sharks	Shrimp	Other
1162	43	0.6	7.0	3.5		0.2	12.6
1163	35	15.2	6.4	6.6		0.0	4.1
1164	24
1165	14	72.4	12.8				5.7
1166	10	96.4				0.0	13.0
1167	13	285.6	10.8	5.0		0.5	102.3
1168	19	17.4	1.1	0.3		0.2	1.1
1169	14	21.7	31.5	1.6		2.0	50.4
1170	15	54.1	16.8	0.4		0.8	29.7
1171	18	26.7	1.0			0.2	18.1
1172	19	116.5	23.8			8.6	4.3
1179	27	369.2	8.9	2.0		0.2	6.1
MEAN		89.6	10.0	1.6		1.0	20.6

OUTER PART

ST. NO.	DEP.	Pelagic	Demersal	Squid	Sharks	Shrimp	Other
1157	29	6.9	22,1	0.8			44.1
1158	76	2.2	46.4	0.9	1.5	4.6	41.6
1159	75	0.2	13.9	2.1		3.3	44.1
1160	58	0.4	52.1			3.6	61.3
1161	53	43.8	0.2	11.4	5.0	0.2	22.4
1174	44	9.7	2.1			2.7	73.9
1175	22	50.4		0.0			3.0
1176	51	25.8	11.4	4,3		1.2	31.3
1177	67	0.7	2.0	4.7		0.2	22.9
1170	54	4.3	18.1	10.8			73.4
1180	15	41.4			2.0
1182	12	182.5	15.4	6.2	17.0	7.4	131.2
1183	48	5.1	3.0	0.3..		16.7	38.0
1184	28	99.2	39.5				357.4
3185	61		43.5			1.1	93.3
MEAN		31.5	18.0	2.7	1.7	2.7	69.2

Table 8. GULF OF VENEZUELA. Catch rates by families for demersal fish in bottom trawl, kg/hour.

INNER PART

ST. NO.	DEP.	Croakers	Snappers	Grunts	Groupers	Glasseyes	Other
1162	43	0.1	5.0		1.9		17.0
1163	35		5.4	0.1	1.0		25.9
1164	24
1165	14	2.4	10.4				78.1
1166	10						109.5
1167	13	10.8					393.4
1168	19	1.1	0.0				19.0
1169	14	31.4	0.1	1.2			74.6
1170	15	5.8	11.0	0.2			84.8
1171	18	0.3	0.7				45.0
1172	19	11.3.	12.5				129.4
1179	27	2.6	6.0		0.3		377.5
MEAN		5.4	4.2	0.1	0.2		112.8

OUTER PART

ST. NO.	DEP.	Croakers	Snappers	Grunts	Groupers	Glasseyes	Other
1157	29		6.6	0.8	1.0	0.8	64.7
1158	76	0.4	34.8		9.2	2.8	50.0
1159	75		9.2	28.9	0.1		25.5
1160	58		26.0	22.2	1.8	2.4	65.1
1161	53				0.2	0.3	82.5
1174	44		0.4		1.7	2.0	84.4
1175	22					0.0	53.5
1176	51		11.1	0.5	0.3	0.3	62.0
1177	67		1.3		0.4	3.8	25.1
1178	54		17.1		0.9	50.2	38.3
1180	15						43.4
1182	12	15.4					344.6
1183	48	0.3	0.7		2.0	0.4	59.8
1184	28	11.2	28.0	206.4	0.3	5.0	245.2
1185	61		33.5	0.3	4.0		100.1
MEAN		1.8	11.2	17.2	1.4	4.5	89.6

Table 9. GULF OF VENEZUELA. Catch rates by families for pelagic fish in bottom trawl, kg/hour.

INNER PART

ST. NO.	DEP.	Sardines	Scombrids	Carangids	Barracuda	Hairtails	Other
1162	43			0.3		0.3	23.5
1163	35			13.6	1.6		17.2
1164	24
1165	14	34.5	1.6	30.0		6.3	18.5
1166	10	33.3	6.0	53.1		4.0	13.1
1167	13	58.0	1.6	222.0		4.0	118.6
1168	19	0.6	6.1	0.2	5.7	4.8	2.7
1169	14	16.0		3.1	0.4	1.0	86.7
1170	15	2.0		41.2	4.0	6.0	48.6
1171	18	24.9		0.9		0.9	19.4
1172	19	82.5	9.0	24.0		1.0	36.8
1179	27	2.0	17.6	38.0	3.2	308.4	17.2
MEAN		21.1	3.4	35.5	1.2	28.0	33.5

OUTER PART

ST. NO.	DEP.	Sardines	Scombrids	Carangids	Barracuda	Hairtails	Other
1157	29	1.5		4.5	0.9		67.0
1158	76			2.2			95.0
1159	75			0.2			63.5
1160	58	0.1		0.3			117.0
1161	53		10.6	33.2			39.2
1174	44		0.4	6.0	2.0		80.2
1175	22	43.2		4.8	2.4		3.1
1176	51	3.7		20.1	2.0		48.3
1177	67	0.0		0.3	0.4		29.9
1178	54		4.3				102.4
1180	15	0.6	10.0	2.0	0.4	28.0	2.4
1182	12	146.6	4.3	0.2			208.8
1183	48			4.8	0.3		58.0
1184	28			99.2			397.0
1185	61						137.9
MEAN		13.0	1.9	11.8	0.5	1.8	96.6

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