The significance of small things
‘Significant’ and ‘small’ don’t usually belong together. We tend to think that ‘significant’ events and things are BIG.
In fact, as with land, it is the very small, the tiny weeny, that are crucial for life in the ocean. That old chestnut phrase ‘the bottom of the food chain’ rolls off our tongue easily, but do we think about what it really means ?
Does it matter if vessels in the Southern Ocean vacuum up swarms of Antarctic krill, in some cases over 1000 tonnes a day? Well, we don’t actually know if this practice is sustainable, meaning leaving enough of this crucial food for whales, dolphins and penguins. The problem is small things whether krill, insects or what we call ‘bait fish (also referred to as forage fish) all have something in common. They are so small we don’t notice them, we fear them (they bite or sting) or we despise them (not big enough for a feed), yet they are all essential in the greater life of the planet. Here in Aotearoa, for example, how many of you have heard of, or noticed the hairy kelp fly (chaetocoelapa littoralis), endemic in coastal areas, living in sea wrack and able to walk on water. Aotearoa is the global centre for kelp fly diversity. Without flies in the world, nothing would decompose – wouldn’t that be fun!?
Among other New Zealand marine scientists Professor Rochelle Constantine has been sounding an alarm for years: - ‘boil-ups’ or ‘work-ups’ (tararukuruku) seen in bodies of water like Tikapa moana, have been disappearing.
These phenomenon are started by one marine species e.g. dolphins noticing a large swarm of ‘bait fish/forage fish ’, such as anchovies or pilchards. They call their mates for a feed and this alerts many other species about a food treasure trove. Quickly fish, sea mammals and seabirds mass in the area. Rochelle has outlined how these small fish, particularly pilchards are a crucial part of our own Tikapa moana resident whale’s (Bryde’s) diet.
What’s causing the disappearance of these small fish? Some blame the overall decline in health of our marine eco-system due to variable factors such as pollution, both dumped and run-offs from the land. Others blame fishing methods such as the 1970s advent of purse-seine fishing (where entire schools of fish are encircled in a large, vertical net) for the decline. An event occurred in the 1990’s that seriously impacted the pilchard population. A mystery virus was imported in fishing bait from Australia, which spread quickly among the pilchard population of Tikapa moana. People reported pilchards dead in their millions. Fishermen say the population has never fully recovered. Bryde’s whales have had to alter their diet. Now the whales mostly eat zooplankton—tiny larval fish.
This change of diet probably means less of this larval fish grow into mature specimens. Scientific studies have shown that certain types of trawling, particularly mid-water trawling, can unfortunately shovel up ‘bait fish/forage fish’ such as anchovies. This is called ‘bi-catch’ and up to recently has been largely glossed over by the fishing industry.
One can only guess how climate change is impacting ‘bait fish/forage fish’ populations. We know that anchovies, for example, feed on plankton (tiny plants and animals). Warming waters are causing plankton to be found more commonly now beyond coastal waters, where cooler conditions are better for their lives. If we are to regenerate marine life in Tikapa moana we need to pay attention to the well-being of its smallest denizens which includes; restricting some fishing methods, potentially re-seeding pilchard larvae into Taikpa moana to get the numbers up again, not allowing any dumping of toxic waste anywhere in the Gulf and its catchments, pressuring our local authority to bring about more timely and stronger consequences for sedimentation causing run-offs and continuing to add our voices to those campaigning on the climate change mitigation front...and when you require a rest from all this mahi go out on a hairy kelp fly safari, take a pic and post it to us at WMP. Small is significant and beautiful.
Postscript: WMP’s Forage Fish pipi is in its scoping phase at the moment, with
the intention to grow this pipi further in the next project phase.
Sue Fitchett
Participant