Marine NZ

Yes! Marine Reserves Actually Work!!

by Roger Grace

 

I had occasion recently to talk to a reporter about marine matters.  Part way through the conversation I was rather shocked when she said "Oh, you think marine reserves actually work then?"  She had obviously been influenced by some of the ridiculous claims emanating from certain recreational fishing sources that marine reserves don't work.  And here she was living within 25 kilometres of two of the oldest and most successful no-take marine protected areas in the country.

 

It is amazing that, with the several examples of long-established successful marine reserves around our coasts, it is possible still to hold the view that marine reserves don't work.  Of course they work!  You just have to go and have a look and it is obvious!  You don't have to be a scientist to understand that if you stop taking fish and crayfish out of a section of coastline, their numbers will build up and the size of individual fish will increase.  Because they are not being taken away they have a chance to grow older and larger and more numerous.

 

There has been a lot of scientific study on this very topic - irrefutable evidence that when an area is given full protection from fishing, the marine life flourishes, fish numbers and sizes increase, and marine habitats change to a state closer to "natural". 

 

But a lot of people don't read scientific papers.  They rely on popular interpretations, magazines, pamphlets and books, talking to people who have swum in marine reserves, or actually jumping in the sea and taking a look for themselves.

 

With this in mind I recently carried out a simple test which anyone with mask and snorkel can do.  Even a ten-year-old could do this test, and come up with their own independent conclusion that, yes, there are more fishes in the marine reserve!

 

Most of you will know Matheson Bay, and Goat Island Bay, both near Leigh, and on comparable pieces of coastline.  Goat Island Bay is the site of the first marine reserve in New Zealand.  It has been protected from fishing for 30 years.  Matheson Bay has always been open to spearfishing, fishing with rod and lines off the rocks, nets, and fishing from boats.

 

There are many similarities between the two beaches and surroundings.  Both sites have similar access, and both are popular for diving and snorkelling.  Large numbers of families picnic on both the beaches.  But take a look underwater and there are considerable differences in the fish life.

 

The simple test I carried out involved snorkelling out off the beach at high tide and counting fishes seen as I swam out from the beach and back again.  At Matheson Bay (7 October 2005) I got in at the beach and swam toward the rocks to the left, crossed the channel and reached the rock platform surrounding the island, identifying and counting fishes on the way whilst snorkelling and observing only from the surface.  I then did a similar count while swimming back to the beach by a different route but through similar underwater country.  In scientific terminology this was a "replicate" count.  On the return route I crossed the channel then swam north along the outside of the rock platform to a narrow opening in the platform, through this gulley and back along the beach to the original point of entry.  The route is shown in the sketch map.  Each leg of the swim took about 15 minutes.

 

A few days later (12 October 2005) I repeated the exercise at Goat Island Bay.  Here I entered the water off the right side of the rock platform and swam across the channel to the edge of the island.  On the return journey I moved west toward Shag Rock, then turned south to the middle of the beach.  Again each leg of the swim took around 15 minutes.  The sketch map shows where I swam.  The bottom types and depths were similar on both legs, and similar to the swims at Matheson Bay.

 

At both areas my swim was done close to high tide and the waves were less than half a metre.  Visibility was 10 metres at Matheson Bay, but only about 5 to 6 metres at Goat Island.  So my viewing conditions were a little better at Matheson Bay than at Goat Island, which might have influenced my counts a little in favour of Matheson Bay. 

 

So, what do you think I saw?  The table shows the fish seen and their numbers for both Matheson Bay and Goat Island Bay.

 

Location	Matheson Bay		Goat Island Bay
Fish species	Swim out	Swim back	Swim out	Swim back
Parore	1	1	20	16
Red moki	1	1	5	2
Goatfish	3	-	-	-
Drummer	-	-	1	1
Snapper	-	-	3	4
Spotty	5	6	2	-
Blue maomao	-	-	1	9
Trevally	-	-	1	-
Column total	10	8	33	32
Location total	18		65
No. of species	4		7

 

The number of individual fishes seen at Goat Island Bay was more than three times those seen at Matheson Bay.  I saw seven species at Goat Island and only four at Matheson Bay.

 

Also what the table does not show is a difference in fish sizes, especially for red moki.  The two red moki seen at Matheson Bay were about 30 centimetres long.  Those at Goat Island Bay were much bigger, older fish, around 60 centimetres.

 

The parore seen were about the same size at both locations, but were much more numerous at Goat Island Bay.

 

Two silver drummer seen at Goat Island were enormous - huge fat fish around 70 centimetres long.

 

Snapper, seen only at Goat Island, were mostly around 40 centimetres - a good legally takeable size if outside the reserve - but also included one giant about a metre long and probably in excess of 20 pounds (over 9 kilos).

 

Do you think those snapper, especially the 20-pounder, would be just out off the beach at Goat Island if people were allowed to fish off the rocks?  Do you think those huge drummer and so many parore would be there if set-netting was allowed?  And would those large red moki be there if spearfishing was allowed?  Of course they would not.

 

A ten-year-old could understand this.  Why is it so hard for some adults to get the same message?

 

There were fewer goatfish and spotty seen at Goat Island Bay than at Matheson Bay.  This might have related to the poorer visibility at Goat than at Matheson on the day I did the counts.  By counting only from the surface, goatfish would have been hard to distinguish against their sandy bottom habitat.  And spotty would have been harder to see against the kelp background.

 

If you were to repeat the counts in summer, there would likely be more species and higher numbers at both locations.  Fish such as blue maomao, sweep, and spotty vary seasonally in abundance.  But I am confident there would still be a big difference between Goat Island Bay and Matheson Bay.

 

The ”Experiencing Marine Reserves" programme, supported by the Nga Maunga ki te Moana Conservation Trust, and the Department of Conservation, has been running in Northland for about four years, and last year extended into Auckland.  Samara Sutherland takes groups of kids snorkelling on a piece of coast not too far from their school, where there is no protection for the marine life.  Then she takes them to a marine reserve, usually Goat Island, which may be a 4-hour bus ride away from their hometown.  They experience for themselves the abundance of fish in a no-take marine reserve and make the comparison with a fished piece of coast nearer home. 

 

Most kids come away enthusiastic to have a marine reserve much closer to home!  Why should they have to travel four hours each way to see fish and other marine life in its natural state?  Just as there is a bush reserve not far from nearly all schools, there should be a marine reserve within an easy drive of all schools.  We owe that to the kids of the present and future.

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