Slippery Customers

Something I didn't reckon on meeting while travelling in New Zealand. The New Zealand Giant Longfin Eel!

This is the largest freshwater eel in the world, with adult females measuring over a metre (up to 115cms). While males are somewhat smaller (75cms) it's also notable that these eels can live to well over 150 years. But what's really impressive about these creatures is their breeding habit. The eel lives mostly in freshwater. rivers and lakes. They will eat most things ('opportunistic feeders' is the term I read) and are thought to be beneficial to the environment as they clean up decayed material that sinks to the bottom. Once the females get to between 20 and 60 years old they begin to think abut breeding and head off downstream to the ocean. Apparently some females can actually cancel this breeding cycle and become sterile - but those that do swim out of the river system into salt water and head for the Tongan trench. It takes months for the eels to get there and when they do they dive to depths of more than 900metres to spawn. Once done the females die. Only a very small percentage of those fertilised eggs hatch and then only a few make it back to a freshwater source to repeat the cycle.

Another interesting fact about these eels is that, when returning from a seawater environment to freshwater they can travel over land to reach water - if the river has been dammed or diverted, records show eels climbing significant distances to reach a lake or river system. Some local councils install fish ladders to assist fish such as trout and eels to travel upstream in areas where the rivers have been dammed.