User menu
This papers looks at data catch assessment survey data collected from the period June 2018-May 2019 with aim to strengthen the monitoring plans for tuna species and improve artisanal tuna data collection. A one-year electronic data collection using a mobile application was piloted at eleven (11) sites with landing sites as the primary sampling unit (PSU) and vessel gear combination as secondary sampling unit (SSU). A total of Composition of tuna and tuna tuna-like species in the sampled catches of sampled biomass of the pooled data indicate tuna species accounted for 38% out of which 5.6% were not identified to species level and 62 % were tuna like species out of which 4.5% were unidentified. The most common species of tuna and tuna like species were yellowfin tuna (Thunnus albacares); Kanadi kingfish (Scomberomorus plurilineatus); Kawakawa (Euthynnus affinis); Bullet tuna (Auxis rochei) and Frigate tuna (Auxis thazard). Thunnus albacares was the most abundant, contributing 29% of the total landings of the sampled catch. The mean length of sampled Thunnus albacares was 84.75±0.64 cm while the minimum and maximum length was 30.5 cm and 180 cm while that of Scomberomorus plurilineatus was 76.82±1.30 cm during the sampling period.
In data poor fisheries, it is difficult to estimate the stock biomass and exploitation rates and fishing mortality which is a measure of fishing pressure. Using length data of fish species length based spawning potential ratio (LBSPR) analysis was conducted to determine the fishing pressure from the different fishing methods. Targeting immature fish could result to a SPR value of 20% and below commonly termed as the limit reference while SPR value of 40% is at an optimum level. The results from this catch assessment survey contributes to enhancing monitoring of these key fish species and also an opportunity to strengthen the monitoring plans for those species and gather more information on the size at maturity which is important in the SPR assessment.
