3.6 The west coast from Cabo Codera to the Paraguana Peninsula

3.6.1 Small pelagic fish
3.6.2 Demersal resources

The coverage in the four surveys of this quite narrow shelf and the slope outside is shown in Figure 3.6.1. A total of 89 trawls hauls were made on the shelf and 30 at depths from 220 to 580 m.

3.6.1 Small pelagic fish

Figure 3.6.2 shows the fish distribution as observed with the acoustic system. Only very low densities were recorded, mostly restricted to the part between Cabo Codera and La Guaira and thus forming an extention of the resources of the Oriente area.

Table 3.6.1 in which the catch data from this shelf is compiled confirms the low availability of pelagic fish in the area. Only few clupeid catches were made consisting mostly of sardinella from the shelf near Cabo Codera. Also catches of barracudas and scombrids were few and with low rates. The guachanche barracuda was somewhat more common than the southern sennet. About 50% of the scombrid catch was chub mackerel, with king and serra Spanish mackerel sharing the other half of the catch in about equal proportions. The carangids seems to be the only group with a consistent and widespread representation in the area. A high number of carangid species appeared in the catches. The following species and groups represented 98% of the catches:

Rough scad, Trachurus lathami	35%
Scads, Decapterus spp.	19%
Lookdowns, Selene spp.	14%
Amberjacks, Seriola spp.	11%
Bumper, Chloroscombrus chrysurus	12%
Bigeye scad, Selar crumenophthalmus	7%

The rough scad gave highest catches east of La Guaira.

Table 3.6.1 West Coast. Pelagic fish. Catch rates in kg/hour by main groups by survey. Mean rate, three highest rates and rate of occurrence. All hauls. los lances.

Survey		Mean rate	Highest rates			Rate of occurrence
	CLUPEIDS
1 February		74	2065,	120,	39	11/31
2 June		10	157,	66,	3	5/22
3 September
4 Nov.-Dec.		5	73,	27,	8	4/22
	CARANGIDS
1 February		53	672,	458,	152	25/31
2 June		25	82,	72,	41	22/22
3 September		12	53,	47,	14	12/24
4 Nov.-Dec.		23	87,	80,	66	22/22
	SCOMBRIDS
1 February		12	288,	28,	19	13/31
2 June		5	56,	12	10	9/22
3 September		1	13,	7,	5	6/24
4 Nov.-Dec.		2	16,	9,	9	10/22
	BARRACUDAS
1 February		6	39,	37,	36	13/31
2 June		2	45,	1,	1	4/22
3 September		1	9,	1,	4	4/24
4 Nov.-Dec.		8	69,	36,	36	10/22

Figure 3.6.1. Venezuela, western and Gulf of Venezuela. Course tracks and fishing stations, by surveys.

SURVEY 1: 23.2 - 5.3 1988

SURVEY 2: 8 - 15.6 1988

SURVEY 3: 9 - 15.9 1988

SURVEY 4: 28.11 - 8.12 1988

Figure 3.6.2. Venezuela, western and Gulf of Venezuela. Fish distribution as registered by the acoustic system, by surveys.

SURVEY 1: 23.2 - 5.3 1988

SURVEY 2: 8 - 15.6 1988

SURVEY 3: 9 - 15.9 1988

SURVEY 4: 28.11 - 8.12 1988

At these low levels of fish density acoustic surveys can not be expected to provide anything but the approximate level of stock biomass. The following estimates could be made:

	PI		P II
Survey 1	14 000	tonnes	18 000	tonnes
Survey 2			2 000	tonnes
Survey 3			32 000	tonnes
Survey 4	7 000	tonnes	37 000	tonnes

On this basis the levels of standing stocks of small pelagic fish in the area can roughly be assessed at:

Clupeids and anchovies	10 000	tonnes
Carangids	22 000	tonnes
Scombrids and barracudas	8 000	tonnes

3.6.2 Demersal resources

The data for the swept area analysis and catch composition of demersal fish comprise 24, 21, 18 and 20 trawl hauls from the respective four surveys. In the analysis the data-sets from the shelf have been analysed by two bottom depth strata: 0-50 m and 50-120m. The shelf off the western region is quite narrow and have been measured by planimeter to 2 000 nm² in the 0-50 m zone and 1 100 nm² in the 50-100 m zone. Only the main points of the analysis with the main species or species groups will be commented upon in the following.

The demersal fish fauna is mainly composed of snappers in both depth zones. The main species are mutton snapper, Lutjanus analis, lane snapper L. synagris, vermillion snapper Rhomboplites aurorubens and cardinal snapper Pristipomoides macrophthalmus. In addition there are some dwarf goatfish Upeneus parvus and some seabreams in the more shallow waters.

Catch composition

Table 3.6.2 shows the mean catch rates in kg/hour and the catch distribution by size classes for the main demersal species caught.

The mean catch for most commercial species are less than 15 kg/hour, only mutton snapper exceed this with 25 kg/hour in the 0-50 m stratum. For the snappers in general the data do, however, not reveal any systematic difference by depth zones, neither in species composition nor catch rates. Table 3.6.3 shows the catch rates summed by species groups. As already mentioned the snappers dominate with a mean rate of 44 and 58 kg/hour for the shallow and deeper strata respectively. Seabreams give catch rates of only 9 and 5 kg/hour for the two strata. Other demersal fish, mainly non-commercial, amounts to about 40 and 42 kg/hour for the two depth zones.

Table 3.6.2 Venezuela west. Mean catch rates and catch distribution by size classes for all swept-area hauls carried out on the shelf.

Species		Mean rate	Number of hauls in catch groups.						Rate of occurrence*
		kg/hour	1-30 kg	30-100 kg	0.1-03 t	0.3-1 t	1-3 t	>3 t
0-50 m
	Mutton snapper	25	26	13	2				41/83
	Lane snapper	11	35	9					44/83
	Dwarf goatfish	6	56	5					61/83
50-100 m
	Mutton snapper	14
	Vermillion snapper	14	46	2	1	1			50/83
	Lane snapper	10
	Dwarf goatfish	7
	Cardinal snapper	7	44	3	1				48/83

* Calculated on basis all hauls total shelf.

Family	0-50 m	50-100 m
Snappers	44	58
Groupers	0	0
Croakers	0	0
Grunts	0	7
Seabreams	9	5
Other demersal	40	42

Biomass estimates

The swept area estimates presented in Table 3.6.4 refer to the main species groups. As most of the species are longlived the variation between the survey estimates could be ascribed either to migration or sampling error. The estimates for the main commercial groups summed varies between about 5 000 and 13 000 tonnes, with close to 8 500 tonnes for all four surveys pooled. This could be a representative figure for the standing stock. The estimates on other fish, mainly non commercial, varies between 3 700 and 8 500 tonnes with 5 400 tonnes as a value from all surveys pooled. Sharks only appeared in a few catches and with low rates in this area.

Table 3.6.4 Venezuela west. Estimates of biomass of demersal fish on the shelf by main groups and surveys.

		Survey 1	Survey 2	Survey 3	Survey 4	All surveys
0-50m
	Snappers	1 850	5 600	2 200	2 750	2 900
	Croakers	50	0	0	250	100
	Grunts	100	0	150	0	50
	Groupers	0	0	80	40	20
	Seabreams	20	1 350	700	500	600
	Other demersal	900	2 600	1 700	5 700	2 600
50-100 m
	Snappers	1 800	5 800	3 100	4 000	3 800
	Croakers	0	0	0	0	0
	Grunts	1 050	0	450	550	450
	Groupers	0	250	200	150	150
	Seabreams	300	200	400	400	300
	Other demersal	3 200	2 700	2 000	2 800	2 800
	Total, main groups	5 170	13 200	7 280	8 640	8 370
	Total, other dem.	4 100	5 300	3 700	8 500	5 400

Squid

The catch rates for the shelf squids, Loligo species were low overall with means for surveys ranging from 2 to 8 kg/hour and highest catches from 9 to 57 kg/hour.

The broadtail shortfin squid Illex coindetti appeared in some quantity in some of the deep hauls with highest rates, up to about 120 kg/hour in the February survey.

Deep sea shrimp

Most of the 30 test hauls in the slope were made at depths between 220 and 400 m. Catch rates for the commercial species were low. The mean rates in the hauls in which the respective species where present and the incidence were:

Royal red shrimp, Pleoticus robustus	3 kg/hr,	8/30
Giant red shrimp, Artistaemorphafolicea	3 kg/hr,	7/30
Megalops shrimp, Penaeopsis serrata	2 kg/hr,	5/30
Parapenaeus longirostris	1 kg/hr,	3/30