In some areas of florida, manatees gather near spring waters during cold weather because the temperature of the springs is always about 72°f. to protect the manatees and the environment, the government closes these areas to people during certain times of the year. evaluate the effectiveness of the restrictions since they went into effect in 1985, based on the data below from ruby springs.
manatee data from ruby springs, 1980-2010
year manatee population manatee deaths due to watercraft
1980 273 25
1990 367 10
2000 399 8
2010 453 8

From the data, the manatee population obviously increased after the regulations went into affect  and the deaths due to watercraft reduced from 25 to 8 after the regulations were put into effect. The population increased by 165% from 1980=-2010 and the drop in deaths due to watercraft decreased by 
68%.So this is not a direct correlation but at least it shows that the watercraft deaths decreased significantly. Since the population increased at a greater rate then it may be that more females were spared so could mate and give birth to that many more manatees.