Poisonous Fish
Many reef fish have toxic flesh, some species at all times and others only at certain times of the year. The poisons are present in all parts of the fish but are especially concentrated in the liver, intestines and eggs. These toxins are water-soluble – no amount of cooking will neutralize them. To make things worse, they are tasteless, so you will find the usual edibility tests ineffective.
Birds are generally unaffected by these toxins, so don’t think that because you see a fish eat them that you can eat them too. Also, cats appear unaffected but dogs and rats are just as vulnerable as humans.
When exposed, these toxins will cause the lips, tongue, toes and fingertips to go numb. There will be extreme itching and a strange, but apparent temperature reversal sensation – cold things will seem hot and hot things will seem cold. There will probably be nausea, vomiting, speech loss, dizziness and a paralysis that will eventually bring DEATH.
To add insult to injury, there are some fish that are dangerous even to touch. For example, many kinds of rays have a poisonous barb in their tail and there are some species of fish that can deliver electrical shocks. Some reef fish, such as stonefish and toadfish, have venomous spines, which, while not fatal, are VERY painful. They cause a burning sensation or even agonizing pain out of all proportion to the apparent severity of the wound.
Jellyfish, which are sometime barely noticeable in the water, can carry powerful stings. The Portuguese man-of-war (not really a jellyfish) is a bluish bladder-like creature with a small fluted sail. Do not enter the water if you see these creatures. They have a very long “streamers” which carry dangerous and painful toxins. Personally, I have never been stung by a jellyfish but whenever I spot one, I immediately get out of the water. It’s an experience I can live without knowing.
Aggressive Fish
There are also a number of ferocious fish that you should avoid. The Barracuda, which is bolder and more curious that one may expect has been known to attack man. It may also charge lights or shiny objects at night. The Sea Bass, which can grow to over 5 ft, can also be aggressive if disturbed. Sea snakes are venomous and sometimes can be found in mid-ocean. While they are unlikely to bite, they should BE AVOIDED.
Sharks
Yes, you knew this section was going to be included. No one can discuss dangerous sea fish without talking about sharks. Only a handful of shark attacks occur each year and only a few are fatal. However, the survivor at sea is more vulnerable than a beach swimmer. Very few types of sharks are considered dangerous to man.
Six (6) sharks account for the majority of human casualties:
- Great White
- Grows to about 18 ft but usually less, is grey above and white below, very thick-bodied with pure black eyes and a stubby conical snout. Located in all oceans but mostly off southern Africa, east and west North America and southern Australia and New Zealand.
- Mako
- Averages 6 – 10 ft, heavy bodied, ultramarine blue above, creamy-white below. Located in all oceans but most abundant in warm, temperate waters. A very fast swimmer and will occasionally leap from the water.
- Tiger
- Averages 10 – 11 ft, heavy bodied, barred or blotched above when young, but when mature they are more evenly greyish above, white below, with a very wide head and jaws and an abruptly squared-off snout. They are found in all tropical and subtropical waters, often close inshore.
- Hammerhead
- These sharks are immediately recognizable by their distinctively flattened hammer-like head. There are several kinds, the largest measuring 18 ft. They are located in all tropical and subtropical waters.
- Bull
- This particular shark is stout, grey from above and white below and grow up to 13 ft. They are aggressive and dangerous in its preference for shallow water and the ability to ascend up rivers. They are usually found in the tropical west Atlantic with close relatives off Southern Africa and in the Indian Ocean.
- Grey Nurse
- Can grow over 13 ft, are heavily built, large finned, with greyish coloring above and white below. Located primarily in the waters off eastern Australia and often found very close inshore.
As a note, Barracudas are not sharks, but should be mentioned. They are thin, torpedo-like fishes, bluish-barred above, brilliant silver below, with a protruding mouth full of sharp teeth. Some kinds grow to 6 ft. They are present in all tropical waters, often in shoals. Very fast and darting, they are usually dangerous only when there is blood in the water.
Great White sharks are the largest of the family, but size is not an indication of danger and is not directly related to the likelihood of attack. A shark smaller than a man can still be a killer. But Basking sharks and Whale sharks may be 44 ft long but they feed on tiny plankton and are not a problem.
Ocean sharks have the ability to kill but, in tropical waters, food is so plentiful that they are not likely to attack humans. Because of this, most of these sharks are generally cowards and can be scared off with the jab of a stick, usually to the nose. However, making a commotion of any type beforehand is likely to ATTRACT them to you.
Sharks live and feed at considerable depth and usually feed off the ocean bottom, but hungry sharks will follow fish anywhere, up to the surface and into shallow waters, if necessary. What a shark explores such water, it is likely very hungry and consequently, VERY DANGEROUS.
A shark will typically eat fish, squid, crabs and a variety of other marine animals but it will seek EASY food and especially stragglers from schools of fish or wounded prey. Sharks will also follow a ship to scavenge refuse thrown overboard.
Sharks mostly feed at night and during dusk or dawn. Because they have small eyes, they have limited vision and locates its prey by smell and water vibrations. It will be attracted by blood from wounds, body wastes and rubbish. Weak and flutter movements will attract a shark because it suggests a vulnerable prey. However, strong and regular movements and loud noises will repel them.
Man’s strange appearance is new to a shark as it doesn’t normally encounter people every day. Clothing will produce a confusing shape and a group of clothed humans bunched together will be safer than an individual. If a shark keeps its distance, then it is merely curious. However, if it circles inward and begins sudden movements, the likelihood of an attack is greatly increased.
Good news is that sharks can not stop suddenly or turn quickly. A good swimmer can evade a single large shark by making rapid changes in direction that a shark can not match.
If You Catch A Shark
If a small shark is accidentally caught, it can be hauled to the side of the raft, the head pulled clear and clubbed hard before pulling it aboard. Make sure it is really stunned before approaching. Club it several times with more blows so you can enjoy some shark steaks.
DON’T try this with a large shark – it could injure you and damage your raft. You must cut off your line and sacrifice part of it as the sharks threshing will likely attract some of its fellows.
Protection Against Sharks
Unless you’re wearing a life jacket or in a craft equipped with shark repellent, the risk of attack is great to anyone in the water. But you should not assume that you are immune to attack. Shark repellent may not be 100 percent effective – but regardless you should use it only when absolutely necessary. But remember, you can use it only once.
In the water:
If sharks are present try not to pass body wastes, which could attract the sharks’ interest. If you must urinate, do it in short, sharp spurts and allow it to dissipate between spurts. Collect fecal matter and throw it as far away from you as possible. If you vomit (and yes, I know this is gross), hold it in your mouth and re-swallow it. However, if this proves impossible, throw it as far as away from you as possible.
If it is necessary to swim, use strong, regular strokes, avoiding fish.
If you happen to have a knife, be prepared to use it. Let the shark take it fully in the snout, gills or eyes.
If a group of people are threatened, they should bunch together and face outwards. To ward off an attack, kick outwards and punch out with a stiff arm using the heel of the hand – like a sports “hand-off”. Make loud noises by slapping the water with cupped hands. Put your head under the water and shout. These techniques are more effective with a group but can be used by an individual as well.
On a raft or boat:
Don’t fish when sharks are around and don’t throw waste overboard (including excrement and fish offal). Let go of baited hooks. Do not trail arms or legs in the water. If a shark threatens to attack, hit it with jabs to the snout with a paddle or pole. Remember, a large shark can do considerable damage to your raft.