5. Results of the fishing experiments.

Some of the results of the fishing operations 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 catches. 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 of fish on the shelf. The results may thus not be comparable to catch rates from special fishing surveys.

The bottom trawl used is a shrimp-cum-fish trawl (see Annex 1) and it may not be as efficient for shrimp as specially designed shrimp-trawls.

Table 1 shows all hauls carried out on the shelf, and grouped according to main categories. The demersal group comprise market value fish such as snappers, groupers, seabreams, croakers and grunts. This group shows markedly higher catch rates than those obtained in any of the previous surveys while pelagic fish are poorly represented. Also shelf squids show low rates in this survey and interesting catches of these resources were only obtained in the March survey. A few night hauls inshore gave some catches of Pe-naeid shrimp, while two deep water hauls gave only low rates of shrimp.

Table 1. Catch rates for main groups standardized to kg/hour.

ST. NO.	DEP.	Pelagic	Demersal	Sharks	Squid	Shrimp	Other
1100	15	41.4		2.0
1181
1102	12	182.5	91.9	17.0	6.2	7.4	54.8
1183	48	5.1	3.4		0.3	16.7	37.6
1184	28	99.2	250.9				146.0
1185	61		37.8			1.1	99.0
1186	69	0.3	61.0		6.9		30.0
1187	32	162.8	22.9	7.2	2.4		11.9
1188	47	10.3	20.6		6.0	0.0	34.0
1189	51	15.2	107.3		30.5	0.2	97.7
1190	51	18.4	134.6	10.3	8.4		76.7
1191	45	98.2	126.0	32.2	5.0	14.4	40.8
1192	46	0.6	63.1			27.6	51.9
1193	503	1.5			3.1	3.6	71.3
1194	316	1.2	8.8	4.5	3.1	1.8	17.8
1195	151	54.0	92.5	16.5	2.5	2.1	38.1
1196	34		0.2		1.2		5.0
1197	22	25.0	912.0				935.6
1198	49	112.0	298.3		2.1		96.6
1199	06	6.0	593.0				42.3
1200	07	0.3	131.3		0.1		50.7
1201	59	6.1	57.0	4.9	1.7	0.1	44.7
1202	46	4.3	305.7		1.4	0.7	72.8
1203	6	417.0
1204	71	1.0	126.2	6.4	0.8	0.4	32.6
1205	19	13.4	0.5		2.2		40.4
1206	71	20.9	205.6	5.2			38.5
1207	22	33.2	29.2				103.5
1208	61	109.6	51.2		0.8	0.3	41.1
1209	100	0.2	11.6	12.0	2.8		6.8
1210	101		49.0			1.0	9.3
MEAN		46.4	122.3	3.8	2.8	2.5	75.1

Table 2 shows the standardized rates of the demersal group by families. Snappers dominate most of the catches and some of the catch rates obtained must be considered good especially when considering the random method of distribution of fishing locations. The high availability of this group on the shelf west of the Guajira peninsula in this survey coincide with a generally low availability in the Gulf of Venezuela and further east and may thus represent a phenomenon of seasonal displacement. Lane snapper, Lutjanus synagris represented 46% of the total snapper catch, while the three larger sized species red - L. purpureus, mutton - L. analis and silk snapper L. vivanus together accounted for 38 %. Of the grunts the tomtate grunt Haemulon aurolineatum dominated with 62 %. The two commercial species of groupers, the red - Epinephelus morio and the black grouper Mycteroperca bonaci represented about 60 % of this family.

Table 3 shows the representation by families of pelagic fish in the catches. Because of gear selection these data are only indicative of the occurrence of the various species. Thread herring was the most common Clupeid and bumper Chloroscombrus chrysurus, round scad Decapterus punctatus, lookdown Selene vomer and rough scad Trachurus lathami dominated the Carangid group.

The complete record of all hauls made are shown in Annex II, and pooled length samples of the most common species caught are shown in Annex III.

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

ST. NO.	DEP.	Croakers	Snappers	Grunts	Groupers	Glasseyes	Other
1180	15						43.4
1181
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
1186	69		46.5	2.0	10.8	1.7	37.2
1107	32	1.8	18.0			3.1	184.3
1188	47		16.4		0.2	4.0	50.3
1189	51		83.0	11.0	12.5		143.6
1190	51		111.8	5.4	14.9	2.5	113.8
1191	45	75.7	41.3	2.4	4.6	1.8	190.6
1192	46		0.4	56.5	6.2		80.1
1193	503						79.5
1194	316				8.8		28.5
1195	151		64.3		28.2		113.3
1196	34				0.2.		6.2
1197	22		889.0	7.0	16.0		960.6
1198	49		154.6	131.6	12.1		210.7
1199	86		515.2	64.8	13.0		48.3
1200	87		101.0	30.0	0.3		51.3
1201	59		35.4	5.2	16.3	0.1	57.7
1202	46		48.8	256.2	0.7		79.2
1203	6						417.0
1204	71		67.8	57.2	1.1		42.0
1205	19		0.1		0.4		56.0
1206	71		145.2	10.2	50.1		64.7
1207	22		26.9	0.2		2.0	136.7
1208	61		22.4	4.0	0.8	24.0	151.8
1209	100		10.4		0.0	1.2	21.8
1210	101	0.0	45.3	2.9	0.2	0.5	10.3
MEAN		3.3	80.8	27.5	6.5	1.5	133.2

Table 3. Catch rates by families of pelagic fish, kg/hour.

ST. NO.	DEP.	Sardines	Carangids	Scombrids	Barracudas	Hairtails	Other
1180	15	0.6	2.0	10.0	0.4	28.0	2.4
1181
1182	12	146.6	0.2	4.3			208.8
1183	48		4.8		0.3		58.0
1184	28		99.2				397.0
1185	61						137.9
1186	69		0.3				98.0
1187	32	17.8	139.9	4.2	0.9		44.4
1188	47	0.1	8.0		2.0	0.2	60.6
1189	51		15.2				235.7
1190	51	6.6	6.3	3.4	2.1		230.0
1191	45	74.8	20.8	0.4	2.0		218.5
1192	46	0.2	0.4				142.6
1193	503					1.5	78.0
1194	316					1.2	36.0
1195	151		50.4	3.6			151.8
1196	34						6.4
1197	22		25.0				1847.6
1198	49	28.0	84.0				397.0
1199	86		6.0				635.3
1200	87		0.3				182.3
1201	59	0.2	5.9				108.6
1202	46		0.8	3.5			380.6
1203	6	409.5	7.5
1204	71		1.8				166.4
1205	19			13.4			43.2
1206	71		20.9				249.3
1207	22		20.8	10.0	2.4		132.7
1208	61		107.2		2.4		93.4
1209	100		0.2				33.3
1210	101						59.3
MEAN		22.0	20.2	1.7	0.4	1.00	207.6

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

Figure 2. Temperature at sea surface.

Figure 3. Hydrographic profiles - GULF OF VENEZUELA 3 - 5.12 1988

Figure 3. Hydrographic profiles - RIOHACHA 10.12 1988

Figure 3. Hydrographic profiles - PENINSULA DE LA GUAJIRA 10.12 1988

Figure 4. Distribution of pelagic fish from acoustic system.