Loss of marine habitats

Part 2 of the Marine Ecology course is about the flora and fauna and their habitat.  This is getting to the heart of why I took this course.

Reading about shellfish on the Te Ara website (The Encyclopaedia of New Zealand), I read this about dredge oysters (or Bluff or flat oysters, or tio):

“After 140 years of dredging, most mullock reefs in Foveaux Strait have been destroyed by heavy equipment, and few sites are available for young oysters to settle. The oyster population in the eastern Foveaux Strait has never recovered since the 1950s, and neither have the mullock reefs. Some environmentalists believe the fishery will collapse if destruction of the reefs continues.”

And from a section on corals:

“Deep-water trawling for orange roughy fish has damaged some coral banks – centuries will pass before their habitat recovers.”

That is why you’ll find oysters in the red zone of Forest & Bird’s Best Fish Guide (see Blogroll links on the left) and orange roughy at the very bottom.

In an unbiased report that summarises the marine biodiversity of NZ, threats are listed as follows:

“fishing, mining, chemical pollution, coastal nutrient and sediment input, habitat loss, aquaculture, invasive species, harmful algal blooms, and climate change. ”  The report goes on to note the effects of these, notably fishing, which “comprise overfishing, habitat modification or destruction, bycatch depletion, and diminishment of ecosystem services because of biodiversity loss.  Impacts that have been documented in coastal waters are now mirrored in the deep sea ….. One study recorded 96 species (many undescribed) of invertebrate bycatch from a deepwater trawl fishery…..The effects of commercial trawling … are well known on soft bottoms in relatively shallow water, in which a single trawler may easily disturb 10km2 in a single day’s fishing. ”  (Gordon, 2010).

There appears to be a general acceptance that common commercial fishing practices are unsustainable, but when it comes to buying fish, from the supermarket, fish and chip shop or restaurant, how many of us ask about the source or fishing methods? 

In the UK, the campaign to raise awareness and change fishing regulations is well advanced, but, here in NZ, campaigns are only nibbling around the edges through Forest & Bird’s Best Fish Guide and Greenpeace efforts.  Habitat is being destroyed, bycatch is being disregarded, species are being pushed to extinction.  The fight needs escalating.  If eating habits don’t change, fishing methods won’t change, and collapse of fisheries and ecosystems will follow. 

In the words of a song my father used to sing – “when will they ever learn?”




Gordon DP, Beaumont J, MacDiamid A, Robertson DA, Ahyong ST (2010).  Marine Biodiversity of Aotearoa New Zealand, PLoS ONE.  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2914018/?tool=pubmed


The state of the ocean (dire)

It’s time to start linking to other blogs and here’s one that grabs the attention – from hot-topic.co.nz.  It concludes:

“This is a cri du coeur from the world’s ocean scientists. We ignore it at our peril…”


The magnitude and rapidity of human impacts on the health of our oceans is far greater than imagined.  It’s up to us to prevent the collapse of ecosystems.

What are the human impacts on the evolution of coastal landforms?

My marine ecology course asked this question in relation to the Moeraki Boulders, the pancake rocks at Punakaiki and Farewell Spit – three iconic coastal features of New Zealand’s South Island.

While researching the terrestrial, atmospheric and coastal influences on these features, the concept that humans could have influenced these features seemed laughable.  These three features have been formed because of a mix, over millions of years, of geologic and coastal processes, plus some fine tuning by weather. 

I was thinking of the erosion caused by visitors’ feet – surely not.  At Farewell Spit, visitors are limited to prevent damage to the fragile ecosystem of the dunes and the mudflats.  I imagined the power of the waves at Punakaiki – human effects must surely be negligible.  And the millions of years to grow a single boulder?  What could humans be doing that could affect these features?

Then I remembered climate change.

We are told that human induced climate change brings bigger and more frequent storm events – leading to more erosion, more deposition, more destruction of fragile intertidal ecosystems.  And rising sea levels – the power of waves will reach higher and further.  And finally acidification of the ocean due to increased absorption of carbon dioxide.  This is particularly relevant in the colder Southern Ocean and is expected to mean that many marine species will struggle to build their shells – this could have an impact on food, and even on the future formation of the ocean substrate.  It may even mean that the sea water is more corrosive.  And what happens when the ocean can no longer absorb our carelessly discharged carbon dioxide?

The effects are, as yet, unknown.   It is our generation’s responsibility to ensure that we reinstate the natural balance.


Plenty more fish in the sea … or is there?

Selfridges, (top London department store) in association with the Zoological Society of London and 20 other conservation and environment groups, is leading “Project Ocean“. 


They are ensuring that their store and restaurants do not sell any endangered fish, they are raising money for the creation of new marine reserves, and they are promoting a fish guide.  Overall, they aim to raise awareness of the threats to our oceans and thereby enable people to make positive decisions about the right fish to buy and eat.

Who in New Zealand will pick this up and run with it?  Logan Brown made a great start.  Forest & Bird are raising awareness and getting their Good Fish Guide out there, and the Greens and Greenpeace are doing their bit, but we need a nationwide chain or household name to pick up the theme and stand by it. 

Pam’s have made a commitment to improve the choice of tuna they sell and its labelling.  Perhaps Pam’s and then Foodstuffs could lead this much needed campaign for NZ.


Seamounts and orange roughy

The introduction to the SIT level 4 marine ecology course relates to the formation of New Zealand’s coastline, its geology, geomorphology and processes.  One of the striking features of the submarine landscape is the seamount.  These are usually volcanic in origin and do not reach the ocean surface, but they can rise to 3 or 4 km from the ocean floor.  The Kermadec Ridge and Colville Ridge to the north of NZ’s North Island comprise many seamounts, the former being younger and still volcanically active, the latter being older and extinct. 

All seamounts are prize marine ecosystems because of their elevation, ocean currents around them, and, in the case of the Kermadec seamounts, the hydrothermal activity.  This means that they are target for the fishing industry and one species in particular is fast losing habitat due to the fishing methods used to harvest it. 

Orange Roughy are bottom dwellers.  Bottom trawling is used to catch them.  It is estimated that some 95% of the ecosystem is destroyed by this method that scrapes along the bottom, particularly on seamounts. 

This method has been described as bulldozing an orchard to harvest a few apples.

Take action by not purchasing orange roughy.  Make your vote count at the supermarket and fishmonger. 




Marine Ecology

How important is it to choose the fish you eat?  Or perhaps should we stop eating fish while the ocean ecosystems recover?  I hope to find out as I embark upon a short course of study – Marine Ecology – with the Southern Institute of Technology.  

With my trusty feline companion beside me, we will go on a voyage of discovery and I want to share what I find out. 

Should we be avoiding all tuna as Greenpeace advocates?  Or is skipjack tuna OK as Forest & Bird suggest in their handy Best Fish Guide?  http://www.forestandbird.org.nz/what-we-do/publications/-best-fish-guide

Is there hope that our oceans will provide food and livelihoods for future generations? 

Have we saturated the oceans with carbon dioxide and destroyed the natural balance?  Have we discarded too much plastic that is now in our seas?  What do these issues mean for us, marine life and the planet?

Too many questions! 

I hope to have a better understanding of the issues as well as a more personal blog site soon!