5. Results from the trawl operations

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 previous fishing surveys. The data from the prepositioned trawl hauls will later be used for estimates of biomass of groups of demersal species.

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 as snappers, groupers, seabreams, croakers and grunts. The average catch of this group is abt. 41 kg/hour, while small pelagic fish is 69 kg/hour, squid 22 kg/hour and Shrimp 2.7 kg/hour. Other fish, generally with a low market value, is at average caught at 70 kg/hour. The total mean catch rate was abt. 200 kg/hour.

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

ST. NO.	DEP.	Demersal	Pelagic	Squid	Sharks	Shrimp	Other
260	53	12.9	8.0	6.4		5.4	96.2
261	12	34.3	16.8	0.3		27.6	16.9
262	11	44.2	9.6			35.9	34.8
263	49	4.6	90.5	2.4		1.0	41.4
264	44	22.0	45.0	135.2			72.2
265	34	93.8	103.8		2.0		15.0
266	66	58.5	4.0	16.0		1.6	65.6
267	73	17.3	8.4	14.4		1.2	100.5
268	70	0.2	8.4	8.6	3.2	0.7	110.1
269	51	16.0	33.6	7.2		4.0	39.7
270	28		22.0				412.8
271	66	103.3	308.3	116.8	1.6		17.2
272	56	59.3	132.8	66.4	90.2		25.2
273	63
274	60	41.2	19.5	67.2	45.4		16.3
275	45	135.0	157.4	176.0	66.0		66.0
276	56	97.0	40.5	84.0	6.8		124.4
277	52	59.0	3.0	3.7		1.7	30.5
278	43		92.1	2.0			56.1
279	64	117.9	12.5	0.4		4.5	74.8
280	50		124.9	2.4			24.8
281	22	0.6	4.0				55.2
282	52	164.2	582.4	72.8			14.0
283	66	65.2	493.4				97.6
284	13		3.8				1.8
285	60	143.2	17.6		5.6		27.4
286	12	34.6	19.9			1.4	16.1
287	28	5.0	60.4	0.1	11.0		12.4
288	75	8.6	51.6	7.0	4.0		6.6
289	24	6.8	43.4	0.8		1.0	17.6
290	67	44.7					5.7
291	19	15.0	8.7		4.4		7.8
292	17	3.2	119.4	1.2	26.0		14.6
293	41	18.6	23.4	0.1	5.0		35.3
294	11	2.1	74.3	4.1		5.4	17.0
295	48	12.6	60.9	1.8	3.2	2.0	38.0
296	67	20.6	4.8	2.0		5.0	52.6
297	42	4.4	1.8	1.8	7.0	0.0	2.8
MEAN		38.5	73.9	21.0	7.4	2.6	49.0

Table 2 focuses on the small pelagic fish around the Guajira Peninsula, and shows the catch by families. The clupeids, mainly threadfin herring and sardinella was caught at average 43 kg/hour, while carangids, mackerel, anchovies and barracudas gave 30, 25, 20 and 10 kg/hour respectively. Most of the hauls in the area were random hauls for swept area estimation, and the figures above do not reflect expected catch rates in a fishery. In our context they could more be interpreted as indicators of a species dominance.

Table 2. Catch rates of pelagic fish by families around the Guajira Peninsula. Kg/hour.

ST. NO.	DEP.	Clupeids	Carangids	Mackerels	Anchovies	Barracudas	Other
260	53	8.0			32.0	2.0	86.9
261	12	11.4		5.4	4.0		75.2
262	11	9.6			10.0		104.9
263	49	36.5	39.8	14.2	3.6	17.0	28.8
264	44	5.6	7.4	32.0			229.4
265	34	51.8	51.4	0.6		5.2	105.6
266	66		2.4	1.6		5.2	136.5
267	73		4.2	4.2	1.4		132.0
268	70		4.2	4.2	8.4		114.5
269	51	19.2	14.4				66.9
270	28	0.7	1.2	20.1	412.8
271	66	35.5	76.8	196.0			238.9
272	56	25.6	99.2	8.0		24.0	217.1
273	63
274	60		17.9	1.6		1.1	169.0
275	45		131.4	26.0		61.0	382.0
276	56		27.0	13.5		102.0	210.2
277	52		3.0			4.0	90.9
278	43	89.4		2.6.	2.4	1.8	53.9
279	64	0.5	12.0			4.4	193.3
280	50	76.8	9.7	38.4	0.8		26.4
281	22	4.0					55.8
282	52	364.0	176.8	41.6.		5.2	245.8
283	66	288.0	23.0	182.4			162.8
MEAN		42.7	29.2	24.6	19.8	9.7	130.3

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.

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

Figure 2. Temperature at sea surface.

Figure 3. Hydrographic profile off Peninsula de Guajira and in the Venezuela Gulf. (GULF OF VENEZUELA 28.2 - 2.3 1988)

Figure 3. Hydrographic profile off Peninsula de Guajira and in the Venezuela Gulf. (PENINSULA DE LA GUAJIRA 5.3 1988)

Figure 4. Distribution of pelagic fish from acoustic system.