Why not close the
snapper fishery during the spawning season?
Then there would be more
fish able to spawn, more eggs in the water and more fish in the
The simple answer is that
more eggs do not mean more fish will survive from that breeding
We are not talking sheep
here. There is no lambing percentage where the number of offspring
is directly related to the number of breeding females.
Female snapper, like most fish, produce
100,000s even millions of eggs each, but the mortality of eggs and
juveniles is extremely high. Almost all of them will die. However
in warm years survival can be 10 times, even 100 times higher than
cold years. Fish have developed a breeding strategy that is more
dependant on environmental conditions than the number of breeding
adults. This is to take advantage of good years.
It's a gamble like rolls
of the fruit machine. Some years they hit the jackpot, when all
the favourable factors line up. Like:
Plenty of food
Even so, if too many young
survive, come winter there will be much less food and too many mouths
to feed. Many will starve and mortality could skyrocket.
it matter when you fish?
What is the difference
if you catch a female snapper during spawning or if you catch a
snapper a week before spawning? Surely it will have the same effect.
That fish wont spawn. What about 6 months before spawning? You still
remove it from the breeding population. What is important is that
each year the reproductive potential of the population is sufficient
to take advantage of the good seasons. Some very successful snapper
spawning seasons have occurred in the 1990's at the current stock
size. 1991, 1995 and 1996 were all strong year classes.
Snapper do not spawn over
a set period of time, spawning is dependant on things like, water
temperature. Also fish may spawn several times during the spring
It would be impossible to
forecast what sort of summer we are expecting in order to forecast
when to allow fishing to avoid catching spawning fish.
You can convince some people
that there is no biological reason that spawning success will be
improved by a ban on fishing during the snapper-spawning season.
Often their real concern will soon surface. "But they take too many"
they say. Snapper school season arrives and those commercial fishers,
or those guys down the road, or those charter boats, they catch
heaps "They are going to wreck it". But these are management issues
– more about the sustainable yield, quota and bag limits –
not issues about spawning success.
A lot of time and money (mostly
funded by cost recovery from commercial fishers) is spent on making
sure that snapper is being fished sustainably. But it is a big fishery
in New Zealand; about 13,000 tonnes a year are landed nationwide.
That's a lot of fish. Probably 12 million snapper taken per year
and about half of those are by recreational fishers. Still the fishing
was very good over the summer of 2002/03 in the Hauraki Gulf but
not so consistent in Northland or Bay of Plenty. Current stock assessment
is that the main east coast snapper fisheries are rebuilding.
A ban on fishing for snapper
during the spawning season would be a disaster. How would you manage
it? For example, where could you fish in the Hauraki Gulf and avoid
catching snapper in spring? You would catch them just about everywhere.
Many fish could survive catch and release but you would also have
to throw back the hook damaged ones to die. Enforcement on the boat
ramps and marinas would be a nightmare. The only way it could work
would be to close the Gulf to all fishing in spring. Imagine the
reaction from the fishing industry and their lawyers. And what about
all the recreational groups, fighting hard to defend our right to
fish in the sea? They would most likely view this as a huge loss
to the public access right. If the same amount of fish were taken
out of the fishery over the whole year then there would not seem
to be any benefit to outweigh the huge disruption of closing areas
during the spawning season.
By John Holdsworth
Blue Water Marine Research
23 August 2003