5. Results of fishing experiments

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 from the Guajira Peninsula to Santa Marta, and grouped according to main categories. The demersal group comprises the families Lutjanidae (snappers), Serranidae (groupers), Sciaenidae (croakers), Priacanthidae (glasseyes) and Pomadasidae (grunts). Pelagic group includes Clupeidae (sardines), Carangidae, Scombridae, Sphyraenidae (barracuda) and Trichiuridae (hairtails). The average catch of demersals is abt. 76 kg/hour, while pelagic fish is 174 kg/hour. Squids and shrimps are scarce in shallow waters, but in the hauls below 200m depth the catch rates of shrimps range from 6 kg/hour to 26 kg/hour. Other fish, generally with a low market value, is at average caught at 72 kg/hour. The total mean catch rate was abt. 335 kg/hour, which is some 50% above the catch rate obtained on the western part of the Venezuela coast. The catch composition by family groups is shown in Table 2 and 3 for demersal and pelagic fish respectively. Demersals are dominated by snappers, the pelagic by sardines and carangids. Anchovies are absent. This family composition is mostly the same as that found in the catches off the Venezuela west coast.

Table 1. COLOMBIA, EASTERN PART. Catch rates for main groups in bottom trawl stations standardized to kg/hour.

ST. NO.	DEP.	Pelagic	Demersal	Shark	Squid	Shrimp	Other
568	453	6.00			1.20	26.50	66.60
569	67	32.20	134.60		0.60		25.40
570	24	86.30	2.00				1.80
571	70	77.00	91.00		2.60		18.00
572	66	188.10	270.90	28.00	14.40		9.90
573	164	5.20	20.40	26.00	7.60		44.40
574	44	24.90	114.08	3.00	9.00	0.14	17.62
575	59	235.90	146.50		1.40		65.80
576	255	3.90	1.80	1.20	0.60	25.20	101.40
577	252	5.60	18.60	4.40	6.00	12.60	79.00
578	309	16.40		58.80	3.20	6.10	60.40
579	404	21.82				15.71	238.34
580	70	80.74	140.74	2.40			83.31
581	45	1510.20	47.60				51.20
582	67	172.00	285.40			5.00	27.00
583	36	232.50	25.20		10.00		54.70
584	71	286.40	110.44				154.00
585	33	1.00	15.00				86.30
586	62	423.40	113.80				32.60
587	23	32.80	6.40				152.20
588	22	722.80	79.60	6.40			156.20
589	69	8.80	168.40		1.80		222.40
590	61	185.00	31.00				36.00
591	110	2.61	51.92				16.30
592	100	0.20	33.40		2.40		22.50
MEAN		174.47	76.35	5.21	2.43	3.65	72.93

Table 2. COLOMBIA, EASTERN PART. Catch rates by families for demersal fish, kg/hour.

ST. NO.	DEP.	Croakers	Snappers	Grunts	Groupers	Glasseyes	Other
569	67		84.60		44.00	18.00	46.20
570	24		2.00				88.10
571	70		87.80			4.80	96.00
572	66	270.00	0.90				240.40
573	164	0.80	18.80		0.80		83.20
574	44		105.94	3.90	0.14	0.44	58.32
575	59		94.90	32.20	18.00	12.60	291.90
580	70		81.08	58.63	56.57		110.91
581	45		47.60			10.00	1551.40
582	67		214.00	10.00	43.40		222.00
583	36		20.70		1.00	2.00	298.70
584	71		64.64	94.40	18.60		373.20
585	33		2.00			4.20	96.10
586	62		94.60				475.20
587	23		0.40		0.40	1.20	189.40
588	22		70.00				895.00
589	69		157.20	180.00			64.20
590	61		31.00			15.00	206.00
591	110		48.01				22.82
592	100		33.40	0.10		2.30	22.70
MEAN		13.54	62.98	18.96	9.15	3.53	271.59

Table 3. COLOMBIA, EASTERN PART. Catch rates by families of pelagic fish in bottom trawl hauls, kg/hour.

ST. NO.	DEP.	Sardines	Hairtails	Carangids	Scombrids	Barracuda	Other
569	67	4.40	1.80	16.40	14.00		160.60
570	24			80.60	1.30		3.80
571	70	1.40	6.00	53.60	15.20	0.80	111.60
572	66		16.20	171.00		0.90	323.20
573	164		5.20				98.40
574	44	4.20		13.20	6.60	0.90	143.84
575	59	112.00		60.20	0.70	63.00	213.70
580	70	19.54		57.09	4.11		226.45
581	45	1282.60		227.60			98.80
582	67	66.00		102.00	4.00		317.40
583	36	156.00		70.50	6.00		89.90
584	71	88.00		198.40			264.44
585	33					1.00	101.30
586	62	244.80		178.60			146.40
587	23	11.60		5.20	16.00		158.60
588	22	720.00			2.80		242.20
589	69			8.80			392.60
590	61	21.00		148.50	6.50	9.00	67.00
591	110		2.61				68.22
592	100			0.20			58.30
MEAN		136.58	1.59	69.59	3.86	3.78	164.34

Table 4 summarizes the catch rates by broad groups for the shelf area between Santa Marta and Golfo de Morrosquillo. The total mean catch rate is 75 kg/hour only, and seen in light of the general hydrographical condition of the area (Fig. 2c) the result of the fishing experiments confirmes that this is a region of very low production.

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

ST. NO.	DEP.	Pelagic	Demersal	Shark	Squid	Shrimp	Other
593	97	4.20	57.80		1.80	9.60	25.90
594	240	0.39	46.96	1.95		1.30	15.25
595	44	6.70	6.60			1.20	24.00
596	101	2.20	24.40		1.20	1.40	8.40
597	30		0.30		0.20		5.30
598	46	12.00	42.90	3.00			15.40
599	35	1.00	65.70		0.20		21.60
600	51	136.84	45.00		2.10	0.48	51.10
601	170	3.18	31.41	2.47	6.00	0.35	12.54
602	64	10.50	24.10	6.80	12.40		20.10
603	39	3.00	0.60		1.20	2.40	7.20
604	71	8.40	4.70	15.20	4.40	0.10	12.30
605	58	6.00	24.00		6.00		28.00
606	80	3.50	15.50	1.40	5.60	0.80	11.20
607	28	10.60	7.20				26.00
608	22	0.23	29.53				29.08
MEAN		13.05	26.67	1.93	2.57	1.10	19.59

Done in Santa Marta
21 June 1988

Figure 2a. Hydrographic profiles.

GULF OF VENEZUELA 11 - 13.6 1988

PENINSULA DE LA GUAJIRA 16.6 1988

Figure 2b. Hydrographic profiles.

ISLAS DEL ROSARIO 19 - 20.6 1988

RIOHACHA 17 - 18.6 1988

Figure 3. Distribution of pelagic fish from acoustic system.