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A Study of the Marine Spiny Crayfish Jasus lalandii (Milne-Edwards) Including Accounts of Autotomy and Autospasy

Migration

Migration

The results of tagging operations in South Africa (Gilchrist, 1918) indicate that considerable movements take place, but in a haphazard manner, probably due to slow wandering in search of food. In the present investigation, of 168 tagged crayfish, nine were returned. One female moved from the middle of Ohiro Bay (point B in Fig. 2) to a point 200 yards off the fish-oil factory at Island Bay, a distance of about 2,000 yards in four and a half months. Two males moved from Moa Point to the extremity of the headland to the east of Moa Point (point C in Fig. 2), a distance of 1,300 yards in five weeks. A female covered the same area in 55 weeks. A male and a female released at point I moved 300 yards in three months, and a male moved the same distance in two and a half months. These are, of course, the minimum distances covered, since the crayfish could have taken any route. No data could be obtained on the movements of the other two specimens.

These limited returns do not point to any definite migration. They indicate that movement is more of a random, wandering nature. The female which was liberated for 55 weeks, and another which was liberated at the same time and returned after 55½ weeks, point to a possible off-shore movement of females. The fact that they eluded capture for over a year and were then retaken in September within a few days of each other suggests that, some time after tagging, they moved to some area not fished (possibly deep water) and then returned to the fishing area (in-shore) in preparation for the release of larvae which begins in September. This is, however, only a tentative suggestion based on two returns, and must await further tagging operations for confirmation.