6. Results of the bottom trawl sampling

The results of the individual hauls are given in Appendix 3 and length frequency distribution for some important demersal species are shown in Appendix 4. The catch rates are standardized to kg per hours trawling. The catches are aggregated in broad groups offish. "Pelagic" comprises Clupeidae (sardine), Engraulidae (anchovies), Carangidae, Scombridae, Sphyraenidae (barracuda) and Trichiuridae (hairtails). "Demersal" includes the families Sciaenidae (croakers), Lutjanidae (snappers), Pomadasidae (grunts), Serranidae (groupers), Ariidae (catfish) and Priacanthidae (glasseyes). This grouping is used in the following description of the composition and catch rates in the bottom trawl fishing.

Table 1 shows all bottom trawls hauls made from the Guajira Peninsula to Santa Marta, grouped according to main categories. The average catch of demersal fish was abt. 63 kg/h which is comparable to the catch rate in western part of Venezuela and also similar to the result of Survey 2.

Table 1. Colombia, eastern part. Catch rates for main groups in bottom trawl stations standardized to kg/hour.

ST. NO.	DEP.	Pelagic	Demersal	Shark	Squids	Shrimp	Other
867	65	24.22	63.22			9.70	37.80
869	484					0.86	0.50
870	71	20.50	19.00	5.40			1.10
871	77	8.70	100.50		0.30		38.70
872	36	159.40	71.30	115.00		0.90	12.60
873	74	145.80	57.60				14.10
874	70	250.54	195.50	16.00	4.50		18.30
875	54	58.40	71.00		1.60		8.80
876	67	92.70	67.80		1.50		15.30
877	71	8.10	146.40	7.80		1.60	34.40
878	298	0.45		2.10	1.58	5.19	99.48
879	421	27.50				8.10	106.85
881	56	8.80	70.60		1.60	16.00	43.60
883	28	1.30	0.90	1.20	1.40		44.10
884	38	12.40	75.40		0.80		10.90
885	56	1.20	5.20		3.90		50.30
886	70	88.80	39.70	25.20	2.40		17.18
887	84	47.80	18.00		0.20		0.20
888	33		88.40		2.00		9.80
889	21		2.00				1.00
890	68	2.10	223.00		6.00	8.00	20.80
893	73	17.40	19.65		0.45		1.65
894	67	13.90	70.60		1.00		43.50
895	65	25.00	46.60				4.30
896	64	65.50	184.20	3.40			23.50
899	142	1.20	9.60	1.20		3.00	144.30
MEAN		41.60	63.31	6.82	1.12	2.05	30.89

The catches of demersal species are dominated by snappers and grunts and the pelagic species of carangid as shown in Tables 2 and 3 respectively. The catches of squids were generally low. In the deepwater hauls the catch rates of shrimp were 5 to 8 kg/h and the maximum value in shallow waters was 16 kg/h.

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

ST. NO.	DEP.	Croakers	Snappers	Grunts	Groupers	Glasseyes	Other
867	65		60.00		1.42	1.80	71.72
869	484						1.36
870	71		16.40			2.00	27.60
871	77		85.80			6.90	55.50
872	36	33.10	37.60		0.60		287.90
873	74		45.00	9.00			163.50
874	70		171.80	1.80		1.20	310.04
875	54		71.00				68.80
876	67		31.70	1.50		13.40	130.70
877	71		28.40	96.00	0.80	1.20	71.90
878	298						108.80
879	421						142.45
881	56	0.40	33.00	29.60	3.60	2.00	72.00
883	28		0.30		0.60		48.00
884	38		40.50	17.20	6.70		35.10
885	56		4.80	0.40			55.40
886	70		22.80	10.80	0.30	1.80	137.58
887	84		17.60				48.60
888	33		12.80		0.80	0.60	86.00
889	21						3.00
890	68		103.00	93.00		13.00	50.90
893	73		18.00		0.75	0.90	19.50
894	67		56.60	3.40	0.60		68.40
895	65		40.60	4.60		0.40	30.30
896	64		157.20	16.00		3.00	100.40
899	142		9.00		0.60		149.70
MEAN		1.29	40.92	10.90	0.65	1.85	90.20

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
867	65	22.80					112.14
869	484						1.36
870	71	0.10		12.60	7.80		25.50
871	77			8.70			139.50
872	36	94.80		64.00		0.60	199.80
873	74			145.80			71.70
874	70	1.34		248.94	0.26		234.30
875	54	45.60		12.80			81.40
876	67	6.20		62.50	5.50	18.50	84.60
877	71		1.60	4.10	2.40		190.20
878	298		0.45				108.35
879	421		27.50				114.95
881	56	2.80		2.40		3.60	131.80
883	28			0.90		0.40	47.60
884	38			12.40			87.10
885	56	0.10		1.10			59.40
886	70	18.90		51.90	18.00		84.48
887	84	21.20		24.00	2.60		18.40
888	33						100.20
889	21						3.00
890	68	0.20		0.30	1.60		257.80
893	73			17.40			21.75
894	67	7.40		6.50			115.10
895	65	24.00		1.00			50.90
896	64			10.50		55.00	211.10
899	142					1.20	158.10
MEAN		9.44	1.14	26.46	1.47	3.05	104.25

The catch rates for main groups in the western part of Colombia the shelf area from Santa Marta to the Gulf of Morrosquillo are shown in Table 4.

Table 4. Colombia, western part. Catch rates for main groups in bottom trawl stations standardized to kg/hour.

ST. NO.	DEP.	Pelagic	Demersal	Shark	Squids	Shrimp	Other
900	22	44.20	18.80			0.70	60.00
901	18	2.60	79.00				30.80
902	39	0.36	42.96				42.84
904	25	3.10	32.70				33.40
905	59	0.30	33.10	12.60	0.70	0.30	21.80
906	38	8.86	57.20	0.40	0.24	2.00	89.40
907	46		169.80		0.60		6.00
908	46	2.80	5.80		16.00
910	33	1.00	13.10		1.00		29.20
911	101		60.00		1.20		2.20
912	95
914	67	5.10	2.00	10.00	5.80	0.60	10.90
915	34	9.50	1.90	1.00	2.30		1.80
916	46	1.40	0.20		0.40		0.50
917	57	5.20	0.30		3.00		4.20
MEAN		5.63	34.46	1.60	2.08	0.24	22.20

The average demersal catch of 36 kg/h is about 50% of the catch rates in the eastern part but higher than in Survey 2. The catches of other groups were small. Snappers was the most dominating species, Table 5. The very muddy or coraline bottom made demersal trawling difficult in the western area.

Table 5. Colombia, western part. Catch rates by families for demersal fish in bottom trawl, kg/hour.

ST. NO.	DEP.	Croakers	Snappers	Grunts	Groupers	Glasseyes	Other
900	22		13.80		5.00		104.90
901	18		68.00			7.00	37.40
902	39	2.40	40.56				43.20
904	25		24.70	0.20		7.80	36.50
905	59	0.60	30.40		1.10	1.00	35.70
906	38		48.50	1.80	6.00	0.90	100.90
907	46		166.20	2.70		0.90	6.60
908	46		5.80				18.80
910	33		11.00		0.10		33.20
911	101		60.00				3.40
912	95
914	67		1.00		0.60	0.40	32.40
915	34		1.20		0.10	0.60	14.60
916	46		0.20				2.30
917	57		0.20		0.10		12.40
MEAN		0.20	31.44	0.31	0.87	1.24	32.15

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

Figure 2a. Hydrographic profiles.

GULF OF VENEZUELA 13 - 14.9 1988

PENINSULA DE LA GUAJIRA 16 - 17.9 1988

Figure 2b. Hydrographic profiles.

RIOHACHA 18 - 19.9 1988

ISLAS DEL ROSARIO 21.9 1988

Figure 3. Distribution of pelagic fish from acoustic system.