Shrimp Trawling in Ungwana Bay A Threat to Fishery Resources.

Abstract

This paper examines the landings of three trawlers fishing the Ungwana Bay (Kenya) over a seven day period totalling about 200 hrs fishing time. A critical analysis is made of the catch and its composition in terms of marketable catch (target species and commercial fish) and bycatch (non-commercial, juveniles and debris). Prawns made up 13.7% of the catch while commercial fish amounted to 14.4% of the total. The remainder (71.9%) comprised of bycatch. Further breakdown showed that non-commercial fish made up the bulk of the by-catch with 42.9%. This group included Branchyura, Apogonidae, Leiognathidae, Squillidae and Gobiidae families. Juveniles accounted for 23.6% of the by-catch. The latter consisted for almost two-thirds of juveniles of commercial fish among which Ariidae were the commonest. Other families included Atherinidae and Carangidae. In the shallow 'Kipini' area, trawling does considerable damage to the benthic fauna and flora. The trawling attracts a large population of piscivorous birds creating artificial and unstable food webs. A Turtle Excluder Device (Anthony Weedless) was used on one of the trawlers but it appeared to result in lower catch of commercial fish allowing only small species and undersized fish into the cod end. It is concluded that the trawlers pose a threat to both the Ungwana fishery and other marine resources.