The blue shark (Prionace glauca) is a species of requiem shark, in the family Carcharhinidae, that inhabits deep waters in the world’s temperate and tropical oceans. Preferring cooler waters, blue sharks migrate long distances. Even though it is the most abundant shark species on the planet, it is listed as Near Threatened by the IUCN.
Although generally lethargic, they can move very quickly. Blue sharks are viviparous and are noted for large litters of 25 to over 100 pups. They feed primarily on small fish and squid, although they can take larger prey. Maximum lifespan is still unknown, but it is believed that they can live up to 20 years.
Blue sharks are light-bodied with long pectoral fins. Like many other sharks, blue sharks are counter shaded: the top of the body is deep blue, lighter on the sides, and the underside is white. The male blue shark commonly grows to 1.82 to 2.82 m at maturity, whereas the larger females commonly grow to 2.2 to 3.3 m at maturity. Large specimens can grow to 3.8 m long. We have not seen blue sharks around the 3m mark off Cape Point, our sightings are typically smaller sharks between 1m and 2.2m. We are still looking forward to our first encounter with a 3m blue shark!
We have been running tours off Cape Point to the Deep for the last two years and it has become a favourite dive of ours. The blue sharks are inquisitive and will approach divers readily, making wonderful photographic subjects with their elongated bodies, long pectoral fins and graceful swimming style in the water. Sometimes, we have only a few individuals with us in the water and at other times there can be dozens of sharks in the area. The dive itself is unique: as scuba divers we are used to looking down at the reef for critters and keeping the reef as our reference point on a dive. Out in the blue, the only points of reference are the other divers and the bait drum, hanging seven or eight metres below a large buoy. Visibility is often in excess of 30 metres and it is quite surreal to watch the light rays dancing down into the depths. Aside from the colour of the water, the temperature is also noticeably different to inshore. It’s not uncommon to leave False Bay at a green 14 degrees and two hours later diving in blue water up to 22 degrees.
The pelagic trip is a long day at sea, departing at first light and back typically in the early afternoon. It’s a must to have good sun protection and a warm jacket in case the wind is chilly. If prone to sea-sickness, some medication to mitigate this is highly recommended. We do provide plenty of drinks and a good packed lunch and there is a head (toilet) on board for you your convenience. Aside from blue sharks, we see other species of sharks, whales, dolphins and a myriad of pelagic sea birds. More about these in the next blog! This is a seasonal activity, starting in late October and running through to late May and it is guaranteed to be an unforgettable marine experience.