1. The white‐spotted wedgefish (Rhynchobatus djiddensis) is a Critically Endangered shark‐like ray in the family Rhinidae. Throughout its Western Indian Ocean distribution, it is targeted for its valuable meat and fins and is reported to have undergone major population declines. However, there remains a need for species specific time‐series data to accurately assess localized population declines.
2. This study used two independent long‐term (37 and 40 years) time‐series catch data from competitive shore angling and shark nets to investigate the size composition and catch per unit effort (CPUE) and conduct a risk assessment for the population on the east coast of South Africa.
3. From 1977 to 2017 the competitive shore fishery captured 7,703 individual R. djiddensis, whilst shark nets in the same region captured 2,856 individuals from 1981 to 2017. Individuals captured in the nets had a sex ratio of 1.8:1 females to males, and were larger than those caught by the anglers. Although the mean annual sizes of net‐caught individuals were above the size of reported sexual maturity, there was little evidence to suggest that any individuals captured were reproductively active.
4. Both the competitive shore fishery and shark net catches exhibited strong seasonal trends with the majority of R. djiddensis catches occurring from October to May peaking in austral summer. Standardized CPUE from the competitive shore fishery declined substantially between 1977 and 2017 and shark net catches exhibited a significant (p < 0.05) fourfold decline in annual nominal CPUE from 1981 to 2017.
5. Ultimately, a risk assessment showed a 65.1% decline in abundance over a period of three generation lengths, which indicates that the sampled population of R. djiddensis in South Africa should be classified as Endangered according to the IUCN Red List using criterion A2b. The conservation implications of this are discussed.

中文翻译：

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南非的濒临灭绝的白斑楔形鱼（Rhynchobatus djiddensis）的长期捕捞趋势和风险评估

1. 白斑的楔形鱼类（Rhynchobatus djiddensis）是Rhinidae家族中一种极度濒临灭绝的鲨鱼状射线。在整个西印度洋分布中，它以贵重的肉和鳍为目标，据报道，人口急剧下降。但是，仍然需要特定物种的时间序列数据来准确评估局部种群的下降。
2. 这项研究使用来自竞争性岸钓和鲨鱼网的两个独立的长期（37年和40年）时间序列渔获数据来调查规模构成和单位捕捞量（CPUE），并对东部人口进行风险评估南非海岸。
3. 从1977年至2017年，竞争性沿海渔业捕获了7,703头R. djiddensis，而同一地区的鲨鱼网从1981年至2017年捕获了2,856头。在这些网中捕获的个体的性别比为雌性和雄性，男女之比为1.8：1，并且更大比那些被钓鱼者抓的人。尽管被网捕的个体的年均规模超过了所报告的性成熟的规模，但几乎没有证据表明捕获的任何个体都具有生殖活性。
4. 竞争性的沿海渔业和鲨鱼网渔获量均表现出强烈的季节性趋势，大多数罗氏梭子蟹渔获量发生在10月至5月，在夏季南方达到顶峰。竞争性沿海渔业的标准CPUE在1977年至2017年期间大幅下降，从1981年至2017年，鲨鱼的净捕捞量每年名义CPUE显着下降（p <0.05）四倍。
5. 最终，一项风险评估显示，在三代人的时间内，丰度下降了65.1％，这表明根据IUCN红色名录，使用标准A2b，应将南非R. djiddensis的抽样人群归类为“濒危”。讨论了其保护意义。