Supplementary material



Supplementary materialText S1. Characterisation of mosquito net fishing in the small-scale fisheries of Northern Mozambique:‘Kutanda’The word Kutanda relates to a traditional form of fishing mainly conducted by women traditionally using cloth such as ‘Kapulana’ wrap-around skirts, but is now widely used to describe the predominantly female form of MNF. More broadly throughout East Africa this practice may also be referred to as ‘Tandilo’ fishing (Bush et al., 2016). Women show a preference for utilising shallow water habitats which is likely related to their swimming ability and restrictions of social norms. Whilst mangroves may have once been a preferred location for Kutanda, since the advent of MNF sand flats and thin seagrass have been described as the preferred habitats for Kutanda. This change in location reportedly relates to: a) a need for wider, open spaces as several MNs (typically between 3 and 7) are sewn together to form a seine net, and b) a desire to avoid habitats where the nets may snag and tear, including thick seagrass which hides sharp bivalves (such as pen shells) and rocks. Many of the OSOL sites are characterised by narrow, sparse patches of mangrove and these may still be used for Kutanda. Coral reefs were specifically cited as avoided, however some fishers said they may use the edge of the reef and rocky areas where visibility is good.MNs are opened lengthways and stitched together at the ends using fishing line or thread. Nets may be adapted to seine netting by attaching floats to the top, usually discarded flip flops, and weights to the bottom, usually gastropod shells. Typically, women fish in groups of three or four in waist to chest-deep water. Nets are stretched between two individuals who may attach the bottom edge to a foot or toe and hold the upper edge just out of the water, slowly dragging the net as a seine. The other one or two people walk a gradually enclosing semi-circle towards the net, splashing the water with their hands or using bowls – this job is sometimes also performed by children. The fish are herded into the seine net, which is gathered by all fishers and the catch sorted in-situ into containers carried on the heads of the splashing fishers. Few species are discarded – mainly pufferfish and juvenile Striped catfish. Fishers reported that fishing trips were usually between 1-3 hrs. This method may also be referred to as ‘Sufria’.Almost all focus groups indicated a preference for fishing during spring tides, though whether high or low tide was preferred depended on local conditions. Most women indicated that during spring tides, unless farming is a priority, they will fish every day. Otherwise fishing frequency was cited as ~3 days per week. Similarly, all sites indicated a higher fishing frequency during the rainy season (Nov – May), citing favourable southerly ‘Kusi’ winds and the positive impact of higher water temperatures on populations of target species as the reason, (though these population fluxes are more likely due to increased freshwater inputs which are of particular importance for early life stages of Engraulidae and Clupidae species (Hoguane, Cuamba, & Gammelsr?d, 2012)). Sites with lots of agricultural activity also cited occupational conflicts as a reason for seasonal fishing preferences, needing to spend more time in the fields during certain times of year, though these timings were said to be becoming less predictable with climatic changes. Fishing at night occurs, largely under a full moon; MN fishers did not indicate nor did we witness the use of artificial lights.All focus groups acknowledged that catches were predominantly of juveniles of these species. Collectively, mixed catches of small fish mainly from MNF are referred to as ‘Medada’ (meaning small mixed fish), and occasionally ‘Dagaa’ by traders from outside the area (a name taken from Lake Victoria fisheries targeting Rastrineobola argentea, the Lake Victoria sardine). A commonly cited benefit of MNF is that women are able to also glean concurrently, meaning numerous species of gastropods, bivalves, cephalopods and crustaceans are also collected.Figure S1. Typical Kutanda catch comprising mostly of G. Oyena. This was the total catch for the day between four women in the village of Malinde.‘Chicocota’Chicocota means simply ‘to drag’. In the focus groups the term was largely used to describe a specific fishing method mostly used by men, but there is some ambiguity over the use of the name and it may be synonymous with Kutanda in some scenarios. Mukuelele was an alternative name sometimes used in the more northerly sites for this method. Whilst women were fully aware of the activity, the female focus groups yielded less detail, so the information given here mainly comes from male focus groups. Chicocota differs from Kutanda in both method and net design. The predominant differences in design are that a) the nets tend to be bigger both in terms of length and depth, requiring more MNs, and b) additional layers of netting from stronger materials are sewn on to the bottom of the net, often a layer of ~15cm of thick gill net and then ~30cm of tough fine mesh netting such as window screen material with weighted bottom edges of rocks or shells and floats on the upper edge using flip flops or plastic bottles. Chicocota may or may not have a cod end, with rice sacks a preferred material for this purpose. Additional materials may require significant financial investment in the gear compared to Kutanda, but allows their use over both reefs and seagrass, and also in open water from boats. In deployment, fishers cited a preference for use over reefs. This may also allow concurrent use of gears such as spear, spearguns and even gillnets, and reflects a tendency to use Chicocota further offshore on longer trips. The larger net requires more force for seining than Kutanda. Therefore nets have a wooden brace or loop straps that go over the shoulders, and multiple men may pull each end through the water. Most fishers in focus groups acknowledged visible damage to corals being caused by Chicocota use. Buckets and/or a canoe may be towed behind for depositing catch. The use of splashing and ‘chasers’ to encourage fish into the net seemed ambiguous, some described it as necessary and others not. A preference for spring tides was cited by fishers, though winds were not seen as a limiting factor for Chicocota, which is engaged in year-round, and night fishing is reportedly common. Some preference was shown for fishing in the dry season for ease of drying fish. Chicocota left staked in the water, to avoid detection when not in use, was witnessed in Lalane.Catches are reportedly larger for Chicocota users, but little detail was gained on target species other than shrimp, which was a predominant focus. It was acknowledged that fishing over reefs gives a broadly mixed catch of fish, around a finger long of multiple species (“too many to count, there are many we don’t know the name for”). Comments on juvenile composition were sometimes ambiguous, but most agreed juveniles are common in the catch. Figure S2. Typical Chicocota catch - this was a subsample of a larger catch from the village of Malinde and contained numerous reef speciesThe ‘Ngoe’ methodAn additional method identified during focus groups, used by men but cited as very rare, was targeting of Ngoe fish (Striped catfish, Plotosus lineatus) using encircling MNs. These nets are small, with a roughly equivalent cod end, and are deployed from a canoe specifically to catch adults of this schooling species (it must be adults due to their harmful spine which means they are discarded when caught as juveniles). The method of capture was described as opportunistic, with little knowledge of how to predict schools of Ngoe; you just “get lucky”. If lucky, however, the catches can be significant; a single catch record was obtained for this method of fishing, operated by a single male fisher and consisting of 16kg of Ngoe in 5 hrs of fishing. Figure S3. Ngoe net following landing of catch fashioned from two to three MNs showing the cod end and attachment of the net to a canoe.Table S1. Proportion of male (n=29) and female (n=74) MNF catch events by fishing zone type (habitat) and vessel type for MNFFishing zone typeProportion of female catch eventsProportion of male catch eventsIntertidal0.760.00Intertidal/shallow reef & seagrass0.160.34Subtidal0.000.41Offshore island0.070.17Vessel type??Foot0.970.28Canoe0.000.62Sail boat0.000.10Motor boat0.030.00Figure S4. Proportion of fishing events conducted by male and female fishers for each gear type. Figure S5. Average cpue for different mosquito net deployment methods by gender of fishersFigure S6 - Species making up 80% of catch once ranked by landed weight for each gear. Gears are ordered dependent on the number of species.Figure S7. Proportion of Kutanda catch species that are above and below length at first maturity values. Species ordered by relative abundance of those assessedFigure S8. Participatory resource and gear use maps for OSOL sitesTablesTable 1 - Summary values for gear diversity comparison, with darker shading representing larger numbers.GearNumber of observationsNo. spp. in totalNo. spp. making up 80% landed weightNo. spp. making up 80% abundanceGill net471062431Speargun43781725Basket trap6371616Spear22531417Beach seine23511012Chicocota2858135Harpoon57132Hand line636222Ring net7322Kutanda604511Figure legendsFigure 1 – Map of study sites in Cabo Delgado, Northern MozambiqueFigure 2 - Example of women fishing with the Kutanda method. Nets may be sewn together but are otherwise unmodified. Fishers may fish in groups of three or four (with either one or two chasers) up to around waist-deep water on sand flats and seagrass beds.Figure 3 - Example of a medium-size Chicocota net (top) and reinforcing done for use over reefs (centre). Example of male Chicocota fishing activity over a fringing reef (bottom). Figure 4 - Combined timeline FGD details from female fishers in the larger villages of Malinde and QuirindeFigure 5 - Violin plot showing distribution of cpue values across predominant gears. Black dots and lines are mean values with standard deviations. GLM comparing cpue between gear types: Adjusted R-squared = 1, F-statistic = 8.313e+12 on 10 and 370 DF, p-value = < 0.005. Gleaning is included in this comparison but excluded from later species-level analyses where only gears predominantly targeting fish were included.Figure 6 - Species accumulation curves from catch events (numbers of fishing trips) for each gearFigure 7 - The top 20 species (ranked left to right) by relative abundance and the proportional representation of each gear in the catch for each species ................
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