FISH DISTRIBUTION BY SPECIES

The catch data with main species are given in Annex I.

The dominant pelagic species are Trachurus indicus, Decapterus russelli, Sardinella gibbosa and S. longiceps. Etrumeres teres, Dussumieria acuta and Scomber japonicus were also common, but in much lesser abundances.

In the region north of Ras al Hadd the pelagic resources were scarce. Off Muscat a scattered distribution of Decapterus russelli was observed (Figure 5).

From Ras al Hadd south to Masira Island the small pelagics resources were made up of Decapterus russelli and Trachurus indicus, mainly in scattered distributions. Two small aggregations were observed near the shelf edge (Figure 5).

On the Masira bank the outer part was dominated by dense registrations of Trachurus indicus while the inner part held considerable resources of Sardinella gibbosa and Sardinella longiceps with an element of juvenile Trachurus indicus.

In Sauqara Bay the shallow areas showed dense registrations of Sardinella longiceps while the outer part had mostly a scattered distribution of a mixture of Decapterus russelli, Trachurus indicus, Etrumeus teres and Sardinella longiceps.

Further westwards the small pelagic resources were made up of clupeoid resources; Sardinella longiceps, S. gibbosa and Etrumeus teres (Figure 5).

Dominating demersal species were Lethrinus nebulosus, Cheimerius nufar and Argyrops spinifer. Frequent in the catches, although in lesser quantities, were Nemipterus japonicus, Ephinephelus diacanthus, Arius thalassinus and Lepidotrigla bentuviae.

Tables 1-4 give catch data by family in bottom trawl sorted according to catch groups and bottom depth strata. Table 1 deals with the hauls north of Muscat, Table 2 from Ras al Hadd to Masira Island, Table 3 the Masira Bank and Table 4 with the Sauquara and Kuria Muria Banks.

Table 1. Distribution of catches in bottom trawl by family and bottom depth strata on shelf north of Muscat.

Table 2. Distribution of catches in bottom trawl by family and bottom depth strata on shelf from Ras al Hadd to Masira Island.

Table 3. Distribution of catches in bottom trawl by family and bottom depth strata on Masira Bank

Table 4. Distribution of catches in bottom trawl by family and bottom depth strata on Sauqara and Kuria Muria Banks.

Pelagic trawling carried out with the research vessel is mainly carried out to identify the acoustic registations and the catches do not reflect the quantities that could be expected in a commercial fishery where gear and engine power are optimalized. With this borne in mind table 5 gives catch distributions of the pelagic hauls carried out on the Masira Bank.

Table 5. Distribution of catches in pelagic trawl by family and bottom depth strata on Masira Bank.

FAMILY	Number of hauls in catch groups (kg/hour)					% incidence in tot. no. of hauls	Mean c. of c. >1 kg	% of total catch	MEAN CATCH IN BOTTOM DEPTH STRATA (kg/hour)
	1-9	10-49	50-199	200-499	>500				<20 m	20-50 m	50-200 m	>200 m
Carangidae	1	0	2	0	6	90	3574.5	95	.0	345.9	4447.5	.0
Sphyraenidae	1	0	1	0	1	50	404.1	4	.0	37.5	157.1	.0
Clupeidae	0	0	1	0	1	20	360.4	2	.0	240.5	.0	.0
Sharks	0	0	0	1	0	10	247.8	1	.0	82.6	.0	.0
Other fish							21.6	0
MEAN OF TOTAL CATCHES							3456.7		.0	755.4	4614.5	.0
NUMBER OF HAULS				10 TOTAL					0	3	7	0

Length distributions from samples of the dominating pelagic species are given in Annex II. Figures 7 and 8 show the pooled length frequency distributions from the statistically unweighted samples of Trachurus indicus and Decapterus russelli. The corresponding distributions from the March 1983 survey are included in the figures for comparison. From Figure 7 it will be seen that in Trachurus indicus the modal length in March corresponds to the 23 cm modal length in December, thus indicating an average growth of 8 cm in 9 months. Juvenile fish in the range of 7-12 cm are observed in December, These are not yet recruited to the main stock near the shelf edge off Masira Bank, but form separate aggregations in shallower waters on Masira Bank and a little east of Salalah. All specimens bigger than 30 cm were caught near Ras al Madraka. The length frequency distribution of Decapterus russelli was observed with two modes in March; 13 and 17 cm, and these have increased to 19 and 25 cm respectively in the last survey, giving an average growth of 6 and 8 cm respectively. As the peaks in the length distribution do not seem to indicate any location dependent growth, two annual spawning periods could be suggested. Longer time periods of data will reveal this pattern more clearly, and in addition to the data gathered from the Fridtjof Nansen surveys the analysis on growth and spawning periods of would benefit from simple length frequency measurements of samples taken locally on a monthly basis. We consider this especially important for the dominating short living small pelagic species.

Figure 8. Decapterus russelli (pooled data)