WIOMSA-CORDIO spawning book Full Doc 10 oct 13.pdf

This seasonal shift was seen in both fishing gears (Figure 4a,b,c,d). Spawning season months(November to February) are defined below and were verified through concurrent studies (Chapters4, 5).Fishers’ knowledge of S. sutor spawning aggregationsInterviewed fishers averaged 29.3±2.2 (SE) years of fishing experience, while those who reportedknowledge of S. sutor aggregations averaged48.6±2.0 years old. The descriptions of S.sutor spawning aggregations from fishers andthe frequency of fishers citing these spawningsigns indicated that awareness of S. sutorspawning aggregations was found in 27 out ofthe 32 fishers interviewed. The most frequentlyreported indicators of possible reproductiveactivity (indirect verification, Colin et al. 2003)were increased abundance of fish (71.9%of fishers) and courtship (40.6% of fishers).Note that basket trap fishers enter the waterwith masks to check and set their traps. OnlyPlate 1: Octopus ink sac and viscera used by Msambwenihook and line fishers as bait for catching rabbitfish fromspawning aggregations. (See colour plates.)14% of fishers said they had observed cloudy/misty substance in water and gravid femaleswith swollen abdomens. Direct observations ofgamete release were reported by two fishers. Outof the 27 fishers knowledgeable about spawningaggregation activity, 15 fishers reported knowledge of sites of spawning aggregations, mentioningsix S. sutor spawning aggregation sites. Twelve of these fishers mentioned the three presumedspawning aggregation sites, A, B, and C, which were cited by 12, 9 and 8 interviewees respectively,and they described indicators of spawning from these sites. The other 3 sites were mentioned by 2fishers each. Fishers from Mvuleni (25 km north of Msambweni) reported that 10 years previously(prior to 2000) they used to target S. sutor spawning aggregations sites off Msambweni, indicatingthat these presumed spawning aggregation sites were well known regionally and have been fishedfor at least a decade (Mzee Hemedi and Mzee Chicho, pers. comm.).Spawning seasonFishers reported that peak spawning aggregation activity occurred between November and February,though reports ranged from March through October (Figure 5). Only 2 fishers reported S. sutoraggregations during June, July or September with no reports of aggregation formation in August.Monthly catch rates varied through the year with the highest CPUE recorded in August (Figure5). Catch rates during the full moon of December doubled that of new moon, but not in January(Figure 5). This information was used to define the purported spawning months of S. sutor asNovember to February, and non-spawning months as March to October.Ninety percent of fishers reported that S. sutor aggregates to spawn during the full moon periodbetween the 14 th and 19 th day of the lunar cycle (Figure 6). One fisher reported spawningthroughout the year.Observations of swollen abdomens and hydrated eggs (Plate 2) were observed during creel surveysof S. sutor catches between November and January but these were not quantified. A concurrentstudy on the reproductive biology of S. sutor from these same catches recorded the highest peak ofgonadosomatic index and running ripe females in November and January (Chapter 4).18