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.


Different standards for cat food?

Having valiantly tried to shop for fish in the green zone of the Good Fish Guide and treating myself to chicken only if it is free range (almost all of the time), I have found myself in a quandary when it comes to food for the mog.

My precious mog prefers fishy offerings – vaguely called ‘ocean fish’ by Chef, with the main ingredients listed as meat by-products, the first listed being chicken.  I have just realised that, despite feeding my cat this food for six years, I have never looked at the ingredients.  For special occasions, I treat her to a tiny tin or two of expensive cat food.  This is where it gets silly. 

The posh nosh for spoiled moggies includes chicken, tuna and snapper. 

1.  If I try only to buy free range chicken, why doesn’t this choice extend to catfood? 

2.  If I avoid tuna, or try only to buy skipjack tuna, up at the top of the Good Fish Guide, why would I buy unspecified tuna for my cat?

3.  If I avoid the worst choices from the bottom of the Good Fish Guide, such as snapper, why on earth would I buy it for my cat?

Discerning shoppers want to make the same wise choices across their shopping – whether food, shampoo, detergent or cat food.

My plea to cat food manufacturers – please give us a choice.  Let us feed our cats ethical, sustainable cat food.

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. 





The news is full of the problems caused by a few farmers who do not recognise the value of protecting the environment – for their community, the health of their stock and for their profits. 

Although effluent management is improving, you have to ask why it has taken decades to recognise the problems caused when effluent is allowed to flow into freshwater, whether from dairy sheds and drains or direct from the cows.  Yet a few old school farmers still treat flowing waterways as effluent ditches and allow their stock to stand, crap in and drink from polluted creeks. 

Imagine this: a tourist from a more enlightened country, visiting because of the 100% pure and clean green image NZ still manages to portray, participates in an ecotourism wildlife trip.  As they journey down the waterway, they pass dairy cows standing in and crapping in the creek.  Not a good look.  Those tourists are also likely to expect our treatment of stock to be to a high standard.  But they might be shocked to see stock huddled together up against a fence with no where else to go, bums to a cold and wet southerly, with no where to shelter. 

Looking after our freshwater and our animals to a high standard is long overdue.