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首页> 外文期刊>Journal of Fish Biology >Reproductive characteristics and population decline of four species of skate (Rajidae) off the eastern coast of Canada
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Reproductive characteristics and population decline of four species of skate (Rajidae) off the eastern coast of Canada

机译：加拿大东海岸四种滑冰（Rajidae）的繁殖特征和种群下降

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Four of the most common species of skate (Rajidae) were studied off eastern Canada to determine if their reproductive characteristics were linked to their population trajectories. The fecundity of the winter skate Leucoraja ocellata, the little skate Leucoraja erinacea, the thorny skate Amblyraja radiata and the smooth skate Malacoraja senta averaged between 41 and 56 egg cases per year for each species. For all species but L. ocellata, males matured at larger sizes and at later ages than females. Theoretical rates of population increase for non-equilibrium populations of L. ocellata (c. 0.07), M. senta (c. 0.14) and L. erinacea and A. radiata (c. 0.20) were low compared to most fishes, indicating that north-west Atlantic skates are intrinsically unproductive, yet are theoretically capable of supporting low-level fisheries. Nevertheless, the results of 36 years of research surveys indicate that the abundance of mature L. ocellata, A. radiata and M. senta all decreased by >90% since 1970, indicating that past fishing mortality (both directed and undirected) has outstripped the net productivity of the skate populations on the eastern Scotian Shelf. The relationship between maximum age (tmax) and age of maturity (tmat) was a better predictor of population growth rate than was body size, with the species exhibiting the highest ratios of tmat :tmax (L. ocellata = 0.68, M. senta = 0.66) having the lowest predicted population growth rates. L. ocellata appears to have the lowest productivity and has experienced the greatest population decline, thus raising concerns over its future status.
机译：在加拿大东部以外的地区研究了四种最常见的滑冰物种（Rajidae），以确定它们的生殖特征是否与种群轨迹有关。每种种类的冬季滑冰Leucoraja ocellata，小滑冰Leucoraja erinacea，棘手的滑冰Amblyraja radiata和光滑的滑冰Malacoraja senta的繁殖力平均每个种类每年41至56个蛋箱。除o。L. ocellata外，所有其他物种的雄性成熟年龄都比雌性大。与大多数鱼类相比，ocellata（c。0.07），s。M. senta（c。0.14）和erinacea和A. radiata（c。0.20）的非平衡种群的理论种群增加率较低，这表明西北大西洋冰鞋本质上没有生产力，但理论上可以支持低级渔业。然而，经过36年的研究调查的结果表明，自1970年以来，成熟的L. ocellata，A。radiata和M. senta的丰度均下降了90％以上，这表明过去的捕鱼死亡率（有向和无向）都超过了斯科特东部大陆架上滑冰种群的净生产力。最大年龄（tmax）和成熟年龄（tmat）之间的关系比体型更好地预测了人口增长率，其中物种的tmat：tmax比率最高（L. ocellata = 0.68，M。senta = 0.66）具有最低的预测人口增长率。 L. ocellata的生产力似乎最低，而人口下降幅度最大，因此引起对其未来地位的担忧。

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