Data from: Variation in responses of fishes across multiple reserves within a network of marine protected areas in temperate waters

Meta-analyses of field studies have shown that biomass, density, species richness, and size of organisms protected by no-take marine reserves generally increase over time. The magnitude and timing of changes in these response variables, however, vary greatly and depend upon the taxonomic groups protected, size and type of reserve, oceanographic regime, and time since the reserve was implemented. We conducted collaborative, fishery-independent surveys of fishes for seven years in and near newly created marine protected areas (MPAs) in central California, USA. Results showed that initially most MPAs contained more and larger fishes than associated reference sites, likely due to differences in habitat quality. The differences between MPAs and reference sites did not greatly change over the seven years of our study, indicating that reserve benefits will be slow to accumulate in California’s temperate eastern boundary current. Fishes in an older reserve that has been closed to fishing since 1973, however, were significantly more abundant and larger than those in associated reference sites. This indicates that reserve benefits are likely to accrue in the California Current ecosystem, but that 20 years or more may be needed to detect significant changes in response variables that are due to MPA implementation. Because of the high spatial and temporal variability of fish recruitment patterns, long-term monitoring is needed to identify positive responses of fishes to protection in the diverse set of habitats in a dynamic eastern boundary current. Qualitative estimates of response variables, such as would be obtained from an expert opinion process, are unlikely to provide an accurate description of MPA performance. Similarly, using one species or one MPA as an indicator is unlikely to provide sufficient resolution to accurately describe the performance of multiple MPAs.

野外研究的元分析表明，受禁捕海洋保护区（no-take marine reserve）保护的生物量、种群密度、物种丰富度以及个体体型通常会随时间推移而提升。然而，这些响应变量（response variable）的变化幅度与发生时间差异显著，其取决于受保护的分类类群、保护区的规模与类型、海洋水文状况以及保护区设立后的时长。

我们在美国加利福尼亚州中部新设立的海洋保护区（marine protected area, MPA）及其周边海域开展了为期7年的协作式非渔业依赖型鱼类调查。研究结果显示，初期多数海洋保护区内的鱼类丰度更高、个体更大，这一现象大概率源于栖息地质量的差异。在本研究的7年周期内，海洋保护区与对照样点间的差异并未出现显著变化，这表明在加利福尼亚温带东边界流生态系统中，海洋保护区的生态效益积累速度较为缓慢。

然而，一处自1973年起便禁止捕捞的老旧海洋保护区内的鱼类，其丰度与个体体型均显著高于对应对照样点。这一结果表明，海洋保护区的生态效益确实会在加利福尼亚海流生态系统中逐步显现，但需经过20年甚至更久的时间，才能检测到因海洋保护区设立而引发的响应变量显著变化。

由于鱼类补充群体格局存在显著的空间与时间异质性，在动态东边界流系统的多样栖息地中，需开展长期监测才能明确鱼类对保护措施的正向响应。通过专家评估流程得到的响应变量定性估算结果，无法准确反映海洋保护区的实际运行绩效。同理，仅以单一物种或单个海洋保护区作为评估指标，也无法提供足够的区分度以准确描述多个海洋保护区的整体运行绩效。