7 hours ago
Blog about "The World's best Shark Dive" by Beqa Adventure Divers. Featuring up to eight regular species of Sharks and over 400 different species of fish, Shark diving doesn't get any better!
When people talk about “keystone” species, they’re generally thinking about predators that shape the behavior of every other creature in their habitat, or about prey that serve as dinner for the entire neighborhood. But a new report on the collapse of coral reefs across the Caribbean is a reminder that entire ecosystems can depend on species that do little more than graze.
So what is this - Longfin or Shortfin?A MASSIVE (in the truest sense of the word) female Shortfin or Longfin (should know soon) Mako Shark estimated at easily 13-14 ft. and 1,000 lbs.The blue sharks, which disappeared immediately, looked like toothpicks next to her.Reportedly the largest Mako ever seen by dive operators in Pico, this enormous shark rocketed from the blue below and swam among us until we ended our dive - in minutes . She was so big at first I thought she was a Great White Shark (a close cousin).The Mako is the top predator in the pelagic (offshore) marine habitat, preying on a variety of big fish (tuna, billfish, etc.) and even marine mammals.And this place has plenty of both.Unfortunately, sharks like this are becoming harder and harder to find because of fishing. I have to say it's the most impressive shark I've ever seen, and this encounter ranks as one of my top experiences in 3,000 dives in 22 years.Truly spectacular - check out the mating scars.The head is pretty much all teeth.
Taking a different approach based on his experiences diving in the western Pacific, marine biologist Walter Starck developed a black-and-white banded wetsuit that was intended to mimic the banded poisonous sea snakes that many sharks appeared to avoid eating (Doak 1974; Nelson 1983).Whilst T. obesus appeared to be unaffected by the banded wetsuit, it was reported to have a repellent effect on C. amblyrhynchos, C. galapagensis, and silvertip sharks (Carcharhinus albimarginatus Rüppell, 1837). Doubt was cast on the effectiveness of the banded suit based on testing performed in the Marshall Islands in the northern Pacific Ocean, but these negative results might have been because the test sites were not inhabited by sea snakes, and local shark populations may not have had the opportunity to learn to avoid them (Nelson 1983).This controversy also serves to highlight the difficulties in assessing repellence when complex multi-sensorial cues are available and the problems inherent in testing shark repellents when sharks must be induced (with food) to interact with them. The repellent effects of some devices may be subtle and provide a useful level of protection against unprovoked bites under normal conditions, but may be significantly reduced when sharks are provoked into feeding, especially when in groups (Gilbert 1962).