Ideasroom

Time to step up to save NZ whitebait

Whether you make your own or grab one down at the local market, the whitebait fritter has a special place in Kiwi culture and with the whitebait season upon us, the nation’s fishers will be out in all weathers for a haul of New Zealand’s ‘white gold’.

But according to a report by the Department of Conservation, three out of five native whitebait species are under threat or, more officially ‘At Risk – Declining’. A fourth is classified ‘Threatened – Nationally Vulnerable’. To put that into context, this threat status puts them in the same category as Brown kiwi or the Great Spotted Kiwi.

National environmental advocacy group Forest & Bird added its own call to ban commercial whitebaiting while a South Island conservation board issued its own dire warning, saying that all five species could be extinct by 2034.

All of which raises the question of whether the days of the whitebait fritter might be numbered and how we got to this point.

Whitebait are juveniles from five species of native freshwater fish, a group known as galaxiids because of the galaxy-like patterning on their skin. When we catch them for fritters they are approximately six months old and rather than the species’ signature patterning effect, are almost transparent.

Whitebait have an interesting life-cycle which is typical of many of New Zealand’s freshwater fish. They spend most of their life in freshwaters and some at sea. Inanga, our most common whitebait species, move downstream to estuaries in autumn to reproduce and wait for a very high tide (spring tide) to travel up into the vegetation on the bank of the estuary where they lay their eggs.

Once the water level drops, the eggs are left exposed around the base of plants and grasses and at the next spring tide the eggs hatch and the larvae swim out to sea. They spend approximately six months at sea, feeding and growing, before returning to freshwater where they grow into adults and the lifecycle starts all over again.

This lifecycle means our whitebait species are particularly vulnerable to a range of problems, from poor water quality and degraded bank habitat in streams and estuaries from human land use such as agriculture or urban land development, predation from invasive fish such as trout, and finally to humans in the form of whitebait fishing.

While it’s hard to know which of the above poses the biggest threat, the key problem likely differs between locations so improving whitebait numbers likely requires all aspects to be managed.

We know that on arrival back in freshwater habitats our whitebait face a few obstacles. First, whitebaiting – humans are blocking off river mouths to capture as many whitebait as possible for commercial and recreational use during the whitebait season. Next, murky waters make feeding difficult for fish and low oxygen levels which are often found in high nutrient waters can lead to high mortality rates. Then land conversion from human development and activities often removes stream bank habitat – crucial for spawning. They may also face blockades in the form of culverts, preventing them from reaching suitable habitat or being eaten by our numerous invasive freshwater fish.

So, the situation for whitebait fish species is challenging but what can we do?

The good news is that we do recognise many of the problems whitebait face, but action is needed.

Fencing and planting our streams is a good first step to ensuring whitebait have sufficient habitat. Importantly, NIWA is currently doing work to understand key spawning habitat for whitebait – once we know this we can ensure these areas are better protected.

Next, streamside vegetation provides shade for streams and is a valuable source of insects for fish to eat while also capturing sediments and using nutrients for plant growth. Over-time streamside planting should lead to improved water quality – but this is a slow process and requires entire river networks to be protected. Luckily, projects such as CAREX, run by the University of Canterbury are looking into solutions to effectively rehabilitate our streams.

Finally, fish passage upstream can be maintained by adding fish passage structures, like fish ladders, into streams. NIWA released guidelines for fish passage in April this year, and fish passage structures have already been widely used by regional councils. There are examples of fish ladders around the country, from Auckland’s Puhinui Stream to streams leading into the Manawatu River.

But if we want to see real and rapid improvement in whitebait numbers, and reduce pressure on our native fish, then we need to consider regulation and whether or not a ban is the only way we can protect this valuable resource (and regulating or banning whitebaiting is going to be the fastest route).

Whitebait will not be saved without some sacrifices. So, are we going to step up to save our native freshwater fish?

Whitebait species and status:

Banded kōkopu (Galaxias fasciatus) - Not threatened

Giant kōkopu (Galaxias argenteus) - Declining

Inanga (Galaxias maculatus) – Declining

Kōaro (Galaxias brevipinnis) - Declining

Shortjaw kōkopu (Galaxias postvectis) – Nationally vulnerable

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