Data_Sheet_1_Density Decline in a Mediterranean Seahorse Population: Natural Fluctuations or New Emerging Threats?.PDF

Illegal wildlife trade is considered one of the most serious threats to biodiversity worldwide, along with habitat loss/degradation and overfishing of wild stocks. Seahorses are considered at high risk as these fish represent an important component of traditional Chinese medicine but are also sold as curios and ornamental fish. On a worldwide level, illegal trade is controlled by numerous laws and regulations, but it seems to continue by assuming more dynamic routes. In the Mediterranean Sea, Hippocampus guttulatus formed one of the largest populations at Mar Piccolo di Taranto in South-Eastern Italy. During the routine monitoring of this population in 2016, a dramatic density decrease was observed. By using questionnaires and long-term datasets, the present study determined possible causes of this decline by investigating habitat changes, temperature trends and the existence of seahorse trafficking while also examining abundance trends during the last decade. The results indicated a sharp density decline starting from 2015, co-occurring with the period of high temperatures, while habitats remained almost constant. However, interviews with main stakeholders described both illegal and legal fishing activities as the main drivers for the declining seahorse density. Indeed, at one of the studied sites, which was under strict military control, seahorse abundance started to decline only after the intensification of fishing pressure in the basin. The study suggests that Mar Piccolo di Taranto could be one of the sources for international seahorse trade, thus highlighting the need for more intense and effective actions to prevent and combat illegal poaching, while threatened populations are requiring continuous and close monitoring. Due to unfavorable socio-economic conditions, a viable and thriving seahorse population at Mar Piccolo di Taranto could contribute to the revitalization of the coastal economy and the development of environmental awareness.

非法野生动物贸易与栖息地丧失/退化、野生种群过度捕捞一同被视为全球范围内对生物多样性最严峻的威胁之一。海马因其既是中医药的重要组成部分，又常被作为观赏水族与工艺收藏品售卖，因此被列为高风险物种。在地中海海域，意大利东南部的塔兰托小海湾（Mar Piccolo di Taranto）曾是斑纹海马（Hippocampus guttulatus）最大的种群栖息地之一。2016年对该种群开展常规监测期间，研究人员观测到其种群密度出现大幅下降。本研究通过问卷调研与长期数据集，结合对栖息地变化、水温趋势、海马走私活动的调查，同时分析近十年的种群丰度变化趋势，明确了此次种群下降的潜在成因。结果显示，种群密度自2015年起出现骤降，这一时间节点与高温期重合，而栖息地环境却基本保持稳定。但对主要利益相关方的访谈结果显示，非法与合法捕捞活动均是海马种群密度下降的主要驱动因素。具体而言，在其中一处受严格军事管控的研究样地中，海马种群丰度仅在该海域捕捞压力加剧后才出现下降。本研究表明，塔兰托小海湾可能是国际海马贸易的货源地之一，这凸显了需采取更有力、高效的行动来防范和打击非法偷猎，同时受威胁的海马种群也需要开展持续且严密的监测。鉴于当前不利的社会经济形势，塔兰托小海湾内健康繁盛的海马种群有望助力沿海经济复苏，并提升公众的环保意识。