Data from: Impact of disease on the survival of three commercially fished species

Recent increases in emergent infectious diseases have raised concerns about the population stability of some marine species. The complexity and expense of studying diseases in marine systems often dictate that conservation and management decisions are made without quantitative data on population-level impacts of disease. Mark-recapture is a powerful, underutilized, tool for calculating impacts of disease on population size and structure, even in the absence of etiological information. We applied logistic regression models to mark-recapture data to obtain estimates of disease-associated mortality rates in three commercially-important marine species: snow crab (Chionoecetes opilio) in Newfoundland, Canada, that experience sporadic epizootics of bitter crab disease; striped bass (Morone saxatilis) in the Chesapeake Bay, USA, that experience chronic dermal and visceral mycobacteriosis; and American lobster (Homarus americanus) in the Southern New England stock, that experience chronic epizootic shell disease. All three diseases decreased survival of diseased hosts. Survival of diseased adult male crabs was 1% (0.003 – 0.022, 95% CI) that of uninfected crabs indicating nearly complete mortality of infected crabs in this life stage. Survival of moderately and severely diseased striped bass (which comprised 15% and 11% of the population, respectively) was 84% (70 – 100%, 95% CI), and 54% (42- 68%, 95% CI) and that of healthy striped bass. The disease-adjusted yearly natural mortality rate for striped bass was 0.29, nearly double the previously accepted value, which did not include disease. Survival of moderately and severely diseased lobsters was 30% (15 – 60%, 95% CI) that of healthy lobsters and survival of mildly diseased lobsters was 45% (27 – 75%, 95% CI) that of healthy lobsters. High disease mortality in ovigerous females may explain the poor recruitment and rapid declines observed in this population. Stock assessments should account for disease-related mortality when resource management options are evaluated.

近年来，新发传染病数量持续攀升，引发了学界对部分海洋物种种群稳定性的担忧。海洋疾病研究的复杂性与高昂成本，往往导致保护与管理决策在缺乏疾病对种群水平影响的定量数据的情况下制定。标记重捕法（Mark-recapture）是一种功能强大但尚未得到充分利用的工具，即便缺乏病原学信息，也可用于量化疾病对种群规模与结构的影响。本研究针对三种具有重要商业价值的海洋物种，利用标记重捕法数据构建逻辑回归模型（logistic regression models），以估算与疾病相关的死亡率：分别为加拿大纽芬兰海域偶发苦蟹病（bitter crab disease）疫情的雪蟹（*Chionoecetes opilio*）、美国切萨皮克湾慢性皮肤与内脏分枝杆菌病的条纹狼鲈（*Morone saxatilis*），以及新英格兰南部海域慢性流行性贝壳病的美洲螯龙虾（*Homarus americanus*）。上述三种疾病均降低了感染宿主的存活率。受感染的成年雄蟹存活率仅为未感染蟹类的1%（0.003~0.022，95%置信区间（95% CI）），表明该生命阶段的感染蟹类几乎全部死亡。中度和重度感染的条纹狼鲈（分别占种群总数的15%和11%）的存活率分别为健康个体的84%（70%~100%，95% CI）与54%（42%~68%，95% CI）。经疾病校正的条纹狼鲈年自然死亡率为0.29，几乎是此前未纳入疾病影响时公认数值的两倍。中度和重度感染的美洲螯龙虾存活率分别为健康个体的30%（15%~60%，95% CI），轻度感染个体的存活率则为健康个体的45%（27%~75%，95% CI）。抱卵雌蟹的高疾病死亡率，或可解释该种群观测到的补充量不足与快速衰退现象。在评估渔业资源管理方案时，渔业种群评估应纳入与疾病相关的死亡率因素。