blue shark, most wide-ranging shark alive

Size
Length: 2–3 m, Weight: 50–100 kg
Lifespan
15–20 years
Diet
Feeds on small fish, squid and carrion. A wide-ranging open ocean shark found from surface down to 300 metres. The most widely distributed shark in world found in every ocean.
Habitat
Deep blue water of open ocean from surface down to about 300 metres. Most widely distributed shark in world found in every ocean following warm currents and schools of squid.
Range
Worldwide distribution. In New Zealand found in deep blue water off continental shelf throughout country. Most common in open ocean from surface down to 300 metres depth globally.
Endemism
Native
Main Threats
Bycatch in tuna longline fisheries is primary threat with millions caught annually. Finning and overfishing also impact populations. Climate change affects prey distribution patterns significantly.
Population
Not Threatened. One of most abundant shark species in world. Common in New Zealand waters. Often caught as bycatch in tuna longline fishery. Population considered stable globally.
Conservation Status
Not Threatened
The elegant ghost of the open ocean. A slim, graceful shark with a long pointed snout. Large round eyes scan the water. Long sweeping pectoral fins cut the current. Deep electric blue covers the back. It fades to a brilliant white belly. The blue fades to grey when the shark dies. This is why live blue sharks are so much more beautiful than dead ones. The colour is life. The grey is absence. Ocean wanderers with a taste for squid. They travel thousands of kilometres across the open ocean. They follow the food and the warm water. They feed on squid, small fish and anything else they can find. Often they gather in large all-male or all-female schools. The segregation is strict. The movement is constant. They are live-bearers. They give birth to litters of up to 100 pups after a year-long pregnancy. The investment is high. The output is significant. The survival rate is low. But the numbers are huge. This is the most common shark in the New Zealand offshore fishery. If someone has ever been on a longliner or a tuna boat, they have seen dozens of them. The presence is ubiquitous. The encounter is routine. They are not aggressive toward humans. They are not considered good eating. Most are released when caught. The flesh is soft. The market is weak. The value is low. So they go back. Sometimes alive. Sometimes not. The outcome depends on the crew. And the sea state. To catch a blue shark is to catch the ocean's taxi driver. The fish that is everywhere. That has seen everything. That keeps the pelagic ecosystem moving. The shark of the bycatch. The one that shows up again and again. Year after year. The reliable face of the deep blue sea. It does not seek attention. It seeks prey. The attention comes anyway. The nets find it. The hooks find it. The lines find it. It is the background noise of the fishery. The constant variable. The expected catch. That is the blue shark. Elegant. Wandering. Common. It carries on. No one told it otherwise. The resilience is biological. The abundance is structural. It occupies the niche fully. It exploits the resource efficiently. It moves with the current. It follows the squid. It survives the net. Mostly. The population remains stable. The distribution remains global. The identity remains consistent. Blue in life. Grey in death. Present in the water. Absent from the plate. It swims on.