The rock crab (Cancer irroratus) fishery is a growing industry in eastern Canada. Considering that American lobster (Homarus americanus) is highly dependent on the rock crab as a food source, questions have arisen as to the impacts such a fishery would have. This study examines how different rations of rock crab can affect somatic growth, condition and ovary development of mature lobster, following molt. We tested the effect of four diets containing various amounts of rock crab, blue mussel and green sea urchin. The four diets were: a reference diet where 80% of the energy was provided by rock crab (T), a diet with half the crab content of the reference diet but containing as much protein (isoproteinic) as the reference diet (E1), a diet without crab but isoproteinic with the reference diet (E2), and a diet without crab but with as much energy (isocaloric) as the reference diet (E3). In general, lobsters fed a diet without rock crab showed lower glycogen and lipid content and higher water content in the digestive gland. Growth of chela muscles was lower, although diet did not have any effect on protein concentration. Ovary development was stunted in females. Differences were mostly striking in diet E3, which contained less proteins than the reference diet. Results obtained from diet E2 were also significantly different from the reference diet and not from E3, suggesting that mussel and urchin, even if given in a greater amount, are not equivalent to crab and cannot fully compensate the absence of this essential component of the lobster's diet. The importance of rock crab for lobster may be due to its high protein content and presence of particular amino acids. Our results strongly suggest that the development and management of a rock crab fishery should be cautious and governed by a multi-species approach.

中文翻译：

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岩蟹 (Cancer irroratus) 对成年美洲龙虾 (Homarus americanus) 生长、状况和卵巢发育的重要性

岩蟹（Cancer irroratus）渔业是加拿大东部不断发展的产业。考虑到美洲龙虾 (Homarus americanus) 高度依赖岩蟹作为食物来源，人们对这种渔业会产生的影响产生了疑问。本研究探讨了不同日粮的岩蟹如何影响成熟龙虾在蜕皮后的体细胞生长、状况和卵巢发育。我们测试了四种含有不同数量岩蟹、蓝贻贝和绿海胆的饮食的效果。四种饮食是：参考饮食，其中 80% 的能量由岩蟹提供 (T)，蟹含量为参考饮食一半但含有与参考饮食 (E1) 一样多的蛋白质（同蛋白）的饮食，不含螃蟹但与参考饮食（E2）同蛋白的饮食，以及不含螃蟹但能量（等热量）与参考饮食 (E3) 一样多的饮食。一般来说，喂食不含岩蟹的饮食的龙虾显示出较低的糖原和脂质含量以及较高的消化腺水分含量。尽管饮食对蛋白质浓度没有任何影响，但螯合肌的生长速度较慢。女性的卵巢发育迟缓。饮食 E3 的差异最为显着，其所含的蛋白质少于参考饮食。从饮食 E2 获得的结果也与参考饮食而不是 E3 有显着差异，这表明贻贝和海胆即使摄入量更大，也不等同于螃蟹，不能完全弥补龙虾这一基本成分的缺失饮食。岩蟹对龙虾的重要性可能是由于其高蛋白质含量和特定氨基酸的存在。我们的结果强烈表明，岩蟹渔业的发展和管理应谨慎，并应采用多物种方法进行管理。