Cape horse mackerel length structure and changes in the older size classes off Namibia

Abstract

Abstract by author:

This research report reviews the size structure of the horse mackerel population inrelation to the regions (latitudes). In addition the length frequency distribution of theolder size classes 20 cm for 2003 and 2004 has also been studied

The results indicated the increase in the fish mean length as the latitude increase with the modal length of 37. 5 cm in the southern region (high latitude) and 17 cm modal length in the northern region (low latitude) during 2004. However the length distribution in the southern region showed unusual trend between the two years with two distinct cohorts each year with 22. 5 cm and 37. 5 cm modal lengths respectively

The student Z-test on the data indicated that there was significant difference in thefrequency distribution of the older horse mackerel ( 20 cm) between 2003 and 2004 with the older fish less frequent in 2004 compared to 2003