Since then, longfin eel catch numbers have continued to decline, and by the 1980s-90s this fell to 1200-1400 tonnes. Prompted by concerns regarding declining numbers of eels, in 2000 the South Island eel fishery was drafted into the Quota Management System, followed by the North Island in 2003 and the Chatham Islands in 2004.Ĭommercial Interest in eels didn’t take off until the 1960’s, and in 1975 eels were the most valuable fish export peaking at around 2500 tonnes caught. Commercial TakeĬommercial harvesting, predominantly for export, is acting as a “nail in the coffin” for a species already decimated by habitat loss and degradation for the decline of eels 6. However there are a variety of factors that enhance the problematic situation. The two main reasons for this extinction crisis are habitat loss and overfishing.
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Don Jellyman (NIWA) has warned that given the long generation times of this species, it may be many years before we know what the full effects of habitat loss and over-fishing are. This will have obvious implications on the number of females present in future spawning populations 5. A recent sample of longfins from a South Island river (the Aparima River) showed that 466 were male and only 5 female 4. Regularly fished rivers now show longfin eel ratios of up to 100 males to 1 or 2 females. Our concern is that very few mature eels are now making it to reproductive maturity with the result that there are now fewer elver recruits. Since the early 1990s the commercial harvest of eels has halved due to this rapidly declining population 3. Very few large longfin eels are now seen anywhere. Commercial catch records reveal a trend of decreasing size of all eels caught, most (in 2007, 96% in the heavily fished Waikato River, 50% nationwide) now being within the lowest size category (220 – 500g). Trap and transfer operations at some hydro dam sites in recent years have revealed that the number of longfin elvers moving up our rivers nowadays is very low – at least a 75% reduction – in stark contrast to the huge elver runs that were witnessed prior to the 1960s. It is considered unlikely that such measures will be sufficient to arrestĪ predicted substantial decline in recruitment of this species.ĭon Jellyman (2007) Alarming Evidence of declines Despite the additional gazetting of reserve areas, Levels of exploitation are not sustainable [Ministry of Fisheries, Science Have led to a recent acknowledgement by fishery mangers that current Widespread concerns that the endemic longfin eel has been overexploited
The declining numbers of Longfin eels is typical of what is happening to populations of freshwater eels worldwide. The longfin eel (tuna) is now classified by the Department of Conservation as “chronically threatened in gradual decline” 1, and is thus in the same category as the Great Spotted Kiwi, NZ Falcon and Kereru (wood pigeon).Ī predicted further decline of 5-30% in the total population is predicted in the next 10 years and that decline is predicted to continue beyond the 10 year timeframe.
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