Sea for yourself
The idea of a marine reserve where large snapper and crayfish can do what they do best – reproduce – is one that should be encouraged. Marine reserves provide just that.
In a country where 33% of our land is protected, a similar conservation ethic should apply to our ubiquitous coastline. However only 7% of our waters are protected. Excluding our two major offshore marine reserves, the figure drops to less than 0.1% of the mainland coast. We have failed miserably to meet our obligations under the New Zealand Biodiversity Strategy of 10% protected by 2010.
Given that 80% of our national biodiversity is found in the ocean, we need more marine reserves. “No fisherman needs more than 90% of the sea to fish in!” says veteran marine biologist, Dr. Roger Grace. “Marine reserves are the ‘National Parks’ of the sea, the only places where the full range of biodiversity is protected and can recover to its natural state.” Recent research by WWF shows that 96% of Kiwis want at least a third of our waters to be protected.
Grace explains that marine reserves are also needed to ensure fish populations are not extracted below levels that are self-sustaining. The maximum sustainable yield (MSY), a system used to allocate fishing quotas, is very high for some species - for example 23% for snapper. This means you can commercially catch snapper until 23% of the original population size remains in our waters - enough to ensure ‘sustainability’.
However, a report released in 2011 by the Ministry of Fisheries stated that “it is becoming increasingly difficult to justify Msy-compatible targets less than 30-40%”. In 2005, the Ministry of Fisheries reported that west coast snapper populations were sitting between 8 and 12% of pre-fished biomass. These stocks are still being commercially fished. Grace estimates that crayfish biomass around the north-east coast of New Zealand could be as low as 1% of the original population.
Kina numbers are controlled by large snapper and crayfish. As soon as we remove these big creatures, kina populations explode, mowing down seaweed forests. Complex ecosystems supported by these forests are reduced to kina-studded ‘barrens’ - not a particularly inspiring sight for snorkelers’ eyes.
Having more marine reserves can help bolster the fish population because they act as nurseries, ensuring population for future fishermen. “They provide a haven for large, old animals which can breed in peace, spreading their progeny around the coast”, says Grace.
Bigger predators also produce more eggs. A 12.5kg female red snapper has the same amount of eggs as 212 females weighing 1.1kg. The next time you reel in a 30-pounder, remember that this egg-making machine will be stocking our future fisheries, and will probably taste like an old boot, so do your grandchildren a favour and throw it back.
There are over 30 marine reserves dotted around the coast. Make the most of the long-awaited summer, and take a look at what a healthy marine ecosystem can look like with our protection.
Photos: Roger Grace Main pic: A network of Marine Reserves in Fiordland protects a rich biodiversity with many deep water species living in accessible shallow waters because of the calm dark conditions brought about by a tannin-stained freshwater layer floating on the sea. Top inset: Large snapper are now common in Tawharanui Marine Reserve, which has been fully protected since 1981. Snapper and crayfish have increased and eliminated kina barrens, allowing the kelp forest to recover to natural levels together with its rich associated biodiversity. Bottom inset: Crayfish have recovered to around 1000 per hectare at Tawharanui Marine Reserve in the extensive kelp forest. Elsewhere on the fished Northland coast you would be lucky to find 2 legalsized crays per hectare on shallow reefs covered in kina, with little kelp.