Marine Parks as a Fisheries Management Tool

Check out our hunting and fishing discussion board.

gee I wish there were more marine parks, click for a larger image Marine parks are an ideal fisheries management tool. There is a strong scientific consensus that they increase biodiversity, increase the number of fish from species targeted by fishermen, guard against the shortcomings of other management tools and guard against the risk of fishery collapse. While most fisheries management tools become less useful as a fishery starts to collapse, marine parks become more useful. For example, quotas, total allowable catches for commercial fishermen and bag limits for recreational fishermen may work well while fish stocks are at healthy levels, but as soon as fish stocks start to decline they offer no protection because they no longer limit catches.

In addition to the claims of increased productivity, experience has shown that protected spots recover very quickly and experience a rapid increase in fish numbers in the first year or two. The only exception to this is where stocks have collapsed completely. There is also a growing consensus that areas close to no take zones receive most of the benefit from the spillover effect.

The failure of traditional management techniques

Traditional fisheries management techniques fail fishermen in two ways. They fail by allowing stocks to collapse despite the best efforts of fisheries managers. They also fail in that they force fisheries managers to set extremely conservative restrictions on both recreational and commercial fishermen in order to overcome the flaws inherent to the techniques that are currently used. Marine parks can help to overcome both of these problems [1, 2], allowing for an increase in catch rates and a more sustainable fishery [3, 4]. If implemented with the active cooperation of fishermen, they can also make enforcement simpler [5], reduce the cost to fishermen of catching a fish and make fishing more convenient [6, 7].

No take zones

There is some confusion as to what the term 'marine park' means. A No Take Zone (NTZ) is a zone where all extractive activities (ie fishing) are banned. This term is often used interchangeably with marine park, however the Australian government has recently started using the term to refer to networks of no-take zones and other special use zones that have been implemented recently up and down the east coast. Unless otherwise stated, the term 'marine park' refers to no take zones in this document. 'Green zone' usually means a no take zone, however the various state governments and the federal government do not have a consistent 'colour coding' scheme for their maps.

Fish to those who value them most

with more marine parks, shore bound anglers could land the occasional big one, click for a larger image As well as increasing total catches and guarding against stock collapses, marine parks are also useful as a tool for delivering fish to those who value them most. Land bound anglers (those without a boat) rarely catch a feed in Australia. They spend more money and time per fish caught than other fishermen and get more enjoyment out of each fish they catch. Likewise, even recreational fishermen with boats value each fish caught far more than the biggest taker of fish - commercial fishermen. Marine parks provide a way to deliver more fish to those who value them most and to save them the expense and effort of owning and maintaining a boat. They can also save fishermen the need to travel long distances to catch fish. It makes no sense at all for commercial fishermen to catch fish near large cities and tourist destinations, while recreational fishermen spend a fortune to travel long distances in gas guzzling 4WD's to places like Fraser Island to fish. There are two ways in which marine parks can achieve this. One is by setting aside areas for recreational fishing only - so called Recreational Fishing Only zones (RFO's). They can also do this indirectly, by having popular, easily accessible shore based fishing spots adjacent to no take zones, where the spillover effect will be greatest. These spots will still have fewer fish than spots you need a boat to get to, so it is unlikely that fishermen with a boat will use them, but they will be a lot more productive than they are now.

The fisheries management approach

There is a tendency among conservationists to focus on ecological factors in choosing locations for no take zones. However, such an approach is not necessary and there are very few situations where site selection is important for conservation or for maintaining fish stocks. A fisheries management approach to marine parks would see more practical issues considered in site selection, such as trying to get the most benefit to shore bound recreational anglers via easily accessible fishing spots. Having no-take zones adjacent to such areas would also aid enforcement. It is very difficult to police a marine park when there is no-one around for miles. On the other hand if there are recreational fishermen along the shore, as well as residents, bathers and tourists, then it would take a very foolish person to try to poach fish from a no take zone, even at night. Finally, if your goal is to maximise sustainable yield then a network of smaller, more numerous marine parks is more suitable.

Towards sustainability

Free range, wild caught animals that are harvested sustainably are one of the most ecologically sound food choices available. They do not require significant modification of the environment, they do not require the raising of animals in inhumane conditions, they do not require vast quantities of chemicals, poisons, hormones and antibiotics. If we are truly committed to sustainability and healthy lifestyles, we will ensure that our fish stocks are well managed and that we have every opportunity to get out and take advantage of them, without a huge expense of money, effort or time.

The problem with size limits

Size limits also have major problems. Undersize fish frequently die after being returned to the water. More significantly, a minimum size creates selective pressure for fish that grow slower, start breeding younger and put more effort into breeding each year than is optimal. In a natural setting, the most successful breeders tend to be the large fish, and it is the fish that quickly grow large that you want to breed, not the runts. Using minimum sizes is similar to a farmer selecting the runts and small unhealthy cattle each year to be the breeding stock for next year, while selling the prize specimens to the meatworks. This problem is suspected to have contributed to the collapse of many previously productive fisheries, and their inability to recover as quickly as would be expected. Not only are there few fish around, but those fish that remain are runts and pursue breeding strategies that are far from ideal for the quick recovery of stocks. Recent research by Heino and Dieckmann suggests that fish respond quickly to these selective pressures and that only a decade of heavy fishing can introduce serious problems. Unfortunately, the time taken to recover from these problems may be far longer than the time taken to introduce them.

Marine parks overcome all of these problems and provide a 'safety net' to guard against factors that are out of our control. When managing a stock that you cannot see, cannot count and cannot assess on a regular basis such safety nets are essential. Marine parks increase total catches through the 'spillover effect'. This refers to the many ways in which they replenish stocks. Mature fish swim out of the no take zones and get caught. They also provide healthy, fast growing breeding stocks and a consistent supply of larvae.

Note that contrary to popular opinion, it is not true that returned fish always grow bigger and get caught again later. The ocean is a harsh place and most of the returned fish die, even if you ignore 'hooking mortality'. For every kilogram of fish returned for being undersize, far less than 1 kilogram of those same individual fish are caught later in their life. It is the total amount of fish caught that matters and while minimum sizes do help by reducing the total catch, they are far less useful than marine parks as fisheries management tools.

Catch limits, maximum sizes and resilience

It is not just minimum sizes that have fundamental flaws. Catch limits and maximum sizes undermine the resilience of a fishery. That is, they increase the risk of fishery collapse. The greatest barrier to effective fisheries management is the enourmous difficulty involved in monitoring the state of the fishery. You cannot easily count how many fish you have left or measure their size distribution. This simple problem is the main cause of the collapse of fisheries. Not only can stocks not be monitored, but recreational catches are a highly variable unknown. Furthermore, fish stocks vary from year to year, due to fishing pressure, rain, water tempreature, disease, the annual spwning cycle etc. These changes cascade up and down the food chain.

Catch limits and maximum sizes contribute to the instability of fish stocks. This is because they provide good protection while stocks are high, but less protection when stocks are low. For example, if the total allowable catch from a commercial fishery is far less than the annual growth of a stock, then the stock will be safe. But if disease, drought or some other problem causes the stock level to fall, then remaining within the total allowable catch will no longer prevent overharvest. Similarly, maximum sizes create instability over longer time periods. While larger fish are still around, they will be protected to some extent, but if they die due to poaching, disease, natural mortality, hooking mortality etc, and few smaller fish make it to the maximum size before being caught, then what was once a safely manageed stock can suddenly be put at risk, after a long period of time of apparently stable catches.

Marine parks overcome this instability. They do not become ineffective like catch limits do when stock levels drop for some unpredictable reason. This benefits fishermen, because it reduces the need to set catch limits conservatively to overcome the flaws in traditional management techniques. Marine parks help to reduce the necessity to enforce underfishing as well as reducing the risk of overfishing.

Relaxation of other management tools

Marine parks will allow the relaxation of other fisheries management tools. Minimum sizes could be reduced without reducing fish stocks. If there was a way to allow fishermen to keep smaller fish while keeping the total catch within sustainable limits, we could increase total catches (by total weight and number of fish) still further. Marine parks provide such a mechanism. Note that some minimum sizes correspond to very nice fish. For example the minimum size for yellowtail kingfish, a very solid pelagic fish, is 60cm in NSW. Obviously such decisions would be made on an individual basis, taking the level of protection each species receives from marine parks into account. With a good network of marine parks up and down the NSW coast, we could also remove the ban on taking blue groper by spear, without preventing people from being able to enjoy diving with these beautiful fish.

How much should be set aside?

One issue that is still contentious is the total area that should be covered by marine parks. Many of the marine parks we currently have around the world have been studied in detail. This, combined with theoretical modelling has led to recommendations for fisheries managers on both the size of each no take zone and the total area that should be covered (Gell & Roberts, 2003). Recommendations from theoretical models tend to range between 10% and 80% coverage, with most people accepting a range of 20-40%. Actual experience backs this up. Marine parks covering smaller areas give a small but noticeable improvement. Networks covering over 20% give a dramatic improvement. I don't think there are any networks with more than 40% coverage. There is only limited guidance on the size of the no take zones, which should be dictated by the range of the most important species for fishermen. The smallest example for which details are available is of 1km across for tropical reef areas. I don't think there are any firm recommendations on the coverage required for conservation purposes, which would tend to be area specific. However, no take zones for conservation tend to be larger to minimise edge effects (effectively to minimise spillover). The scientific consensus says the same thing, outlining the benefit to fishing and advising that no take zones for fisheries management be smaller than no take zones for conservation of biodiversity. Note that a network of marine parks is required, not just a few isolated no take zones.

It is important for conservationists to remember that exceeding the optimum level of protection actually does more harm than good, by concentrating effort in too small an area. To reach sustainable yields from a very small area, fishermen will end up putting in much more effort, which is itself destructive when you take into account things like bait consumption, bycatch etc. Once a reasonable network of marine parks is established, the marginal benefit from more marine parks is reduced and probably becomes negative. In this situation, other methods become the only effective tool for ensuring sustainability and should become the focus of further investigation.

There is unlikely to be a 'sharp' optimum. That is, there will be range of values for which the benefit to the fishery will be roughly equal to the maximum benefit (for the mathematicians, this is the familiar scenario that the slope of the curve of benefit vs coverage will be zero at the maximum). This means that other issues can be taken into account to a limited extent. It seems reasonable to have a target of 20% coverage, to get close to the optimum level without the risk of exceeding it, while giving due consideration to issues of convenience for anglers.


Spearfishing is the most ecologically sustainable fishing method. Spearfishermen are very selective and can completely avoid harming protected species and undersize fish. They do not harvest bait or pay others to harvest bait for them. They do not leave fishing line, nets, hooks, lures or lead sinkers lying around. They do not leave stainless steel hooks in fish. They do not remain fishing in overfished areas, instead moving on and letting them recover. Where possible, fisheries management tools should be designed to encourage spearfishing.

While shallow (<20m depth) coastal reef needs to be protected just like other 'representative' areas, care should be taken not to overrepresent such areas for no take zones and to choose areas that are hard for shore bound spearfishermen to access or that are unsuitable for spearfishing due to frequent poor local conditions (visiblity, current, swell etc).


Download the statement of scientific consensus here. Download the paper by Gell and Roberts recommending 20-40% no take zone coverage here (177kb pdf). Download an article by Ulf Dieckmann and Mikko Heino on selective pressures from minimum sizes here (1.6MB pdf).

Biodiversity and site selection

In selecting site for no take zones, there is an unfortunate tendency among all stakeholders to focus on the number of fish that are currently at each location, rather than the potential a site has for holding fish. This is a core element of what is often termed a 'Representative Areas Program' (RAP). Obviously some sites have natural features suited to certain ecosystems, such as reefs, mud, sand, calm protected waters or water exposed to strong currents or wave action. However, in terms of what a no take zone will manage - fishing effort and the impact that has on the food web - one of the strongest predictors of biodiversity will be current fishing effort, which is going to become irrelevant once you remove that effort.

Fortunately this has tended to work in the favour of a fisheries management approach, because those areas with the most fish tend to have so many fish because of less effort, which is usually due to some kind of inconvenience for fishermen to get to that spot. This also happens to make it and ideal location for a no take zone.

So why does this matter?

First of all, it adds weight to the idea that site selection is fairly irrelevant from a conservation perspective, as experience has shown us that even the most overfished sites respond very quickly to protection and fish numbers skyrocket over the year or two following protection. Obviously a representative areas program still makes sense for choosing a few samples of each type of spot (reef, mudflat, sand etc), but basing a representative areas program on the fish and other mobile biota that inhabit each location does not make a lot of sense. In other words, giving convenience for shore bound anglers a very high priority in selecting sites will not have a conservation downside.

Why are all my fishing spots being taken away?

The second reason that it matters is that it goes a long way to explain a curious disparity in response to marine parks from the fishing community. On the whole, the fishing community either supports marine parks or tolerates them because they acknowledge the need for them. After all, most Australian fishermen are the weekend warrior variety who are lucky not to have to stop in for fish and chips on the way home. But invariably there is a small band of fishermen who are completely opposed to marine parks, and they are often the most experienced and respected fishermen. They tend to act as though there is some kind of conspiracy against them, as that is the only readily available explanation for why all of their favourite spots have been placed off-limits. But the explanation is much simpler. What makes these the favourite spots for experienced fishermen is the same thing that makes them seem attractive for no take zones. That is, the presence of fish, which is at least in part due to some obstacle preventing most fishermen from accessing the spot.

It is true that these fishermen will have to make the most changes, but the interests of the vast majority of fishermen outweigh any inconvenience to them. It is a choice between placing the no take zones in an area that is inconvenient for far more fishermen, placing it in an area that is likely to remain barren even with protection (flat, sandy bottom) and choosing those areas that knowledgable fishermen have already discovered. In any case, the experienced fishermen are still well positioned to take advantage of the new opportunities that arise. The fishing spots are not taken, just moved, and the experienced fishermen will end up getting more benefit from the increased productivity than the amateurs.

Some people just don't like change

When minimum sizes and catch limits were first introduced, a small but vocal minoirty of fishermen complained bitterly about them. They demanded proof that they were necessary. They blamed problems on other types of fishermen. They claimed that it would destroy the enjoyment of fishing and that the complexities involved would force them to give up fishing. Then a curious thing happened. Despite being ignored in the political process, many of these fishermen came to accept the new regulations. But it didn't stop there. They went beyond acceptance to incorporating minimum sizes and catch limits as personal ethical or moral standards. They even went as far as to create a myth of scientific validity behind what are essentially arbitrary beureucratic choices. They told their children that throwing the little ones back is good because you get to catch the same fish when it is bigger. They repeated it so often that they began to believe the simiplistic slogans themselves and eventually stopped thinking about what it really meant.

Fast forward to today, and the same thing is happening again. The difference is that now we have the added argument that 'traditional' management tools, which have only been around a short time, are somehow ideal, from a scientific, moral and recreational perspective. The scientific validity is pure myth, as many of the current management practices have obvious flaws. The moral validity has no sound basis either. There is nothing inherently immoral about taking smaller fish. It is the total amount taken, and the collateral damage you do along the way that matters. It is sustainability that matters. The recreational perspective amounts to nothing more than old fishermen being stuck in their ways. Having a different minimum size for each species and a different bag limit for each species is far more complicated than a common no take zone for all species. Management tools that do not inconvenience fishermen at all until they take up boat fishing are obviously far simpler. There is no rational justification to burden future generations with unnecessarily complex legislation merely because current fishermen grew accustomed to them over a few decades and cannot get their head around new ideas.

So will marine parks also be accepted in the future? There tends to be a consistent pattern where new marine parks are introduced. At first there is always some opposition to them, but like other management tools fishermen come to accept and promote them.

No boat fishing zones in rivers

One of the greatest opportunities for the use of marine parks as fisheries management tools, and one which is yet to be taken advantage of, is the idea of 'no boat fishing zones' along tidal rivers with 'developed' coastlines. There are plenty of suitable rivers up and down the east coast of Australia. Such a zone would give the smallest effective size for a no take zone, and the highest ratio of edge length to protected areas - taking the concept of smaller, more numerous marine parks to the extreme. It also takes to the extreme the concept of delivering as much of the benefit as possible to the shore bound recreational angler. Obviously such a scheme would not apply to a whole river and there would be plenty of spots upstream and downstream that would be more productive to anglers who have the ability to reach them, because they would be away from the throngs of tourists fishing along the edge of the no boat fishing zone. These spots would also benefit from the spillover effect.

Shore orientation and site selection

Along any stretch of coastline, the shore will tend to face predominantly in one direction. This is often the direction from which prevailing winds and prevailing swells come. Any stretch of shoreline (especially one with good 'structure' for holding reef fish) that faces away from or at a significant angle to this direction is highly valuable for fishermen, especially spearfishermen. Where possible such sites should be left open to fishing, while sections of shoreline facing the predominant direction should be favoured for no take zones. This is unlikely to interfere with the selection of representative areas as these locations will be exposed to swell when the wind blows backwards and will be very similar, from a biodiversity perspective, to other sites.


I am at ease with the park system we have in victoria even though I lost a couple of spots. It has made unproductive areas in the bay productive again and spots near parks now have significantly more fish. The ban on scallop dredging has probably helped here as well though. Happy spearin', Greg


from fuscus:

In the early 80s I was employed catching aquarium fish in Cairns when they first introduced zoning. We lost access to a number of reefs including Michaelmas Cay.

We hated it.

However in the next couple of years we noticed a significant increase in the numbers of some species, particularly Chaetodontidae and (surprisingly) coral trout, on the open reefs.

Of course, this is hardly a proper scientific study but in our case the zoning system had no effect on the business at all.

[Note: the increase in coral trout numbers was surprising because peculiarities in their life cycle (eg starting life as a female then changing sex to male, preying upon young of their own species) had led some commentators to doubt the benefits of marine parks for this species.]

Have you noticed any changes after a marine park was introduced near you? If so, please let us know.

join discussion