Catch Assessment Surveys on Lake Victoria have been plagued with inconsistencies in data collection since the onset of harmonized sampling in July 2005, with some years (2009, 2012 and 2013) completely missing data while other have data collected in only one month (Table 9). Seasonal variations affect fish catches and basing on one sampling to provide annual estimates for the lake may result into biased estimates. Between July 2005 and December 2015, 15 Catch Assessment Surveys (CASs) were conducted at 56 pre-selected fish landing sites in the Ugandan part of Lake Victoria comprising approximately 10% of all landing sites in each of the former 11 (currently 15) districts sharing the lake. The CASs’ were conducted following regionally harmonised Standard Operating Procedures (LVFO, 2005). This report covers the CAS conducted in December 2015 and puts into context the trends generated by results of the previous surveys. A total of nine fish species groups (including others) were recorded during the December 2015 CAS. There was a 44.6% reduction in the estimated annual fish catches from 269,533 metric tonnes (MT) in 2014 to 149,382 MT in 2015. Similar to the previous two CASs in 2011 and 2014, Mukene dominated the commercial catch on the lake (65,268.6 MT, 43.7%). This was followed by Nile perch (37,219.3 MT, 24.9%), the haplochromines (15,072 MT, 10.1%) and Tilapia (13,278.2 MT, 8.9%). Comparing with the May 2014 CAS, all the three major commercial species (Nile perch, Tilapia and Mukene) registered declines in their monthly and annual catches (tables1&10). Despite forming the largest bulk of the total catch on the lake, the total beach values of Mukene remained significantly lower compared to the large size species, Nile perch and Tilapia whose combined catch was lower than that of Mukene. Mukene fetched 49 billion Uganda shillings (11.8%) in annual beach revenue compared to the 220 and 68.5 billion from Nile perch and Tilapia respectively. Overall, there a reduction in beach revenues generated from the three top commercial species compared to the May 2014 survey.
The catch rates (kg/boat/day) of Mukene were highest in the Catamaran boats using lift nets followed by the sesse motorized boats using small seine (Lampara) nets and was least in parachute boats small seines. For Nile perch, the ssesse motorized boat seine boats registered the highest catch rates (51.4kg/boat/day) followed by the flat boat seine boats (33.4kg/boat/day), the ssesse motorized long line boats (31.7kg/boat/day) and the ssesse pointed boat seine boats (30.8kg/boat/day). The Tilapia fishery on the other hand registered highest catch rates in the sesse pointed boats operating boat seines (18kg/boat/day) and the ssesse motorized boats using cast nets (16kg/boat/day).
The use of illegal fishing gears like beach seines, monofilament gillnets, cast nets, and basket traps was evident in the December 2015 CAS as evidenced by their highest catch rates for the target species (appendix 3). The continued use of these illegal gears to harvest the target species especially the Nile perch and tilapia is unsustainable for these fisheries and could be the main cause for the observed large declines in the two fisheries on the Lake. Management efforts on the lake need to be geared towards eliminating these illegal fishing practices. The very low beach values from Mukene catches despite their large contribution should be a matter of concern particularly along the value chain from post harvest handling, value addition and marketing. The CASs on Lake Victoria should cater for seasonal variations as per the SOPs in order to provide accurate and reliable estimates of the lake catches.