Short-term impacts and value of a periodic no take zone (NTZ) in a community-managed small-scale lobster fishery, Madagascar

The small-scale lobster fisheries of Madagascar’s impoverished southeast coast account for the majority of national catch and export, making a significant contribution to the regional economy. Data suggests catches have declined, likely due to over-exploitation. In response, the community of Sainte Luce has established a locally managed marine area (LMMA) to manage their lobster fishery, including a 13 km2 periodic no take zone (NTZ). Participatory monitoring data were used to assess compliance, identify changes in catch per unit effort (CPUE) associated with the NTZ and consider the short-term value of the NTZ. Compliance is low for measures dictated by national legislation (minimum landing size (MLS), national closed season, prohibition on landing berried females), but may be higher for those designed by the community (NTZ). Upon NTZ opening in July 2015, an estimated 435% increase in catch was observed compared with the mean for the preceding five months, a product of increased effort and significantly higher CPUE. Zero Altered Negative Binomial modelling showed CPUE was significantly higher during the NTZ opening in 2015 and in 2016 when the opening period had been moved. Whilst it is unlikely that tangible ecological benefits have accrued from NTZ operation, there have been important socio-economic effects. Specifically, there was a 33% increase in the price fishers received, a significant effect at the bottom of the value chain. Temporary increases in catch and income acted as a catalyst, engaging neighbouring communities in fishery management, resulting in two additional NTZs. Attention is drawn to the fact that current national legislation may be sub-optimal and should be reviewed. Successful management of the regional fishery will require the state and industry to support communities in adopting community-based management. The NTZ measure considered here may be an effective tool to achieve this.马达加斯加贫困东南沿海的小型龙虾渔业占全国捕捞与出口总量的绝大多数，为区域经济作出了重要贡献。相关研究数据显示，捕捞量呈下降趋势，推测其原因是过度捕捞。为此，圣卢斯社区设立了本地管理海洋区（locally managed marine area, LMMA）以管理当地龙虾渔业，其中涵盖一块面积13平方千米的定期禁捕区（periodic no take zone, NTZ）。研究借助参与式监测数据，评估了禁捕区的合规情况，识别了与禁捕区相关的单位捕捞努力量渔获量（catch per unit effort, CPUE）变化，并测算该禁捕区的短期效益。国家立法规定的相关管理措施（最小上岸规格（minimum landing size, MLS）、全国禁渔期、禁止上岸抱卵雌虾）的合规率较低，而由社区自主制定的禁捕区相关措施，其合规率则相对更高。2015年7月禁捕区开放后，相较于此前五个月的均值，捕捞量预计增长435%，这一增幅源于捕捞努力量提升与单位捕捞努力量渔获量显著升高的共同作用。零调整负二项模型（Zero Altered Negative Binomial modelling）分析结果显示，2015年禁捕区开放时段，以及2016年调整后的开放时段内，单位捕捞努力量渔获量均显著升高。尽管禁捕区的运行尚未带来明确的生态效益，但已产生了重要的社会经济影响。具体而言，渔民的渔获售价上涨了33%，这一效应在价值链底端体现得尤为突出。捕捞量与收入的短期提升起到了催化作用，吸引周边社区参与渔业管理，进而新增了两处禁捕区。研究同时提请注意，当前国家立法或并非最优方案，应予以修订完善。要实现该区域渔业的有效管理，需要政府与行业支持社区推行以社区为基础的管理模式。本次研究涉及的禁捕区措施，或可成为达成这一目标的有效工具。