However the occasional shortfin mako or porbeagle shark is also caught. Thresher sharks like the one in this photo are considerably more rare in Canadian waters. Other species of shark do occur in Nova Scotian waters. However many of them prefer warmer waters that are associated with the Gulf Stream, or deeper waters which make them unlikely to be caught by recreational anglers. Below is a map of the area just off Halifax along with the location of many of the blue sharks that have been caught during recent Halifax-Dartmouth shark derbies.
Some fishers chum the water first to attract any sharks that are nearby.
Water temperatures above 18 degrees Celsius are usually associated with greater catches. The number of shark derbies and participants has been increasing ever since their inception, and biological data has been collected at each of them every year. Most of the sharks caught during the derbies are landed rather than released. It is from these animals that lengths, weights, sexual maturity and stomach contents can be recorded and analyzed. Vertebrae are sometimes collected for age determination.