The rock lobster fishery is one of the most lucrative and well-resourced and managed fisheries in Tasmania, and yet it is on the verge of calamity, and no one seems particularly keen to do anything about it.
This is not the first time that the rock lobster fishery has been in crisis. In the 1990s a new quota system was introduced in an attempt to make the commercial fishery more sustainable and more economically viable. Until a few years ago this appeared to be working and the biomass was slowly increasing, despite the catch being set at an optimistically high level.
Unfortunately, poor recruitment* over at least the last two years has meant that many more rock lobsters have been removed from the water than were replaced by natural processes. It appears that the scientific modelling that has underpinned the management of rock lobster did not take into account periods of low recruitment, and it now seems that all the gains made since the introduction of quota in the late 1990s have been completely lost.
As if this was not bad enough, local area depletions have been an obvious problem for many years and yet no real progress has been made to do anything about it. It is common knowledge that many once productive areas have been stripped of rock lobster. In particular, recreational hotspots have suffered greatly and many once popular fishing areas have been completely fished out.
This was really brought home to me on a recent dive I did at Bicheno. Using a piece of sophisticated diving equipment called a closed circuit rebreather (CCR), which enables divers to spend extended periods under water, I did a long dive from the northern end of the gulch around to the break wall at Waubs Bay. On any of the numerous shorter dives I did in this area on normal scuba during the 1980s I would have expected to see several rock lobsters.
During my recent long dive, covering much more area than any of those previous dives, I should have expected to see many more. In fact, I did not see even one individual during this entire dive. The absence of rock lobsters has become a normal feature of dives outside marine protected areas (MPAs) on the East Coast of Tasmania.
Another problem that has developed over the last 20 or so years is widespread Centrostephanus rogersii urchin barrens. The primary cause of this appears to be related to the almost complete removal by fishing of large rock lobsters from the population along this coast of Tasmania.
Large rock lobsters are important predators on Centrostephanus sea urchins. If the predators are removed, the urchin population increases. The urchins feed on the macroalgae that normally cover shallow rocky reefs. If there are too many urchins, the lush vegetation disappears and shallow rocky reefs become barren and unproductive. This loss of production is not only ecologically significant but has huge implications for fisheries. It is estimated that activity for both rock lobster and abalone is reduced by 70% in urchin barrens.
Fishing on Tasmania’s east coast has been removing almost every rock lobster soon after it reaches legal size for many years. This so-called knife edge fishing means that, unless a completely different approach towards managing rock lobster is taken, there can be no expectation that stocks of large rock lobsters capable of eating Centrostephanus sea urchins will develop to the point where urchin barrens can be controlled.
The Tasmanian Conservation Trust has been warning the government about the situation since the mid-1990s, but still no management processes have been implemented to deal with this problem.
You would expect rock lobster fishers to be up in arms about the whole situation. After all, it is not just the environment that is suffering but also the fishers’ own fishing activities. Unfortunately, this is not the case. While it is true that many commercial fishers are very concerned, it appears that, so far, short-term financial considerations seem to be more powerful motivators than long-term concerns about fishery sustainability or ecological impacts for many. Even the most obvious solution to overfishing, a reduction in catch, appears to be difficult for many to accept, and it will be interesting to see if members of the commercial Tasmanian rock lobster fishery make the necessary tough decisions at a series of meetings that will be held over the next couple of months.
Many recreational fishers are probably not even aware that these problems exist. A thing called sliding baselines is probably the reason for this. This relates to the way people perceive their environment. For example, if many recreational fishers who have only been fishing for the last 10 years would most likely be completely unaware that there used to be many more rock lobsters in most locations and that they were much easier to catch.
So what should be done to help the rock lobster fishery recover? The first thing needed is a significant cut in the total allowable commercial catch (TACC). This will quickly take some pressure off the fishery and bring fishery production more into line with rock lobster recruitment.
The second thing that needs to be done is to introduce a maximum size limit across the state. This will protect the large rock lobsters that are so important in controlling urchin numbers.
Thirdly, area-based management needs to be introduced so that the Tasmanian rock lobster fishery can be regulated on a region-by-region basis. This will allow the fishery to be managed in a way that is sensitive to the wide variety of local conditions found around Tasmania.
Fourthly, large areas of the east coast need to be temporarily closed to rock lobster fishing, to allow numbers of large individuals to increase to the point where they will be able to prevent the creation of new urchin barrens and restore current urchin barrens to normal reef habitat. If this is not done, we can expect most of the lush productive shallow rocky reefs off Tasmania’s east coast to be turned into a barren rocky desert over the next 10 or 20 years.
The fifth issue that needs to be addressed is the recreational catch. While this sector only takes a small proportion of the total catch, it is likely very significant in local areas, particularly on the East Coast. The thing about recreational fishing is that it continues well beyond the point where commercial fishers give up because fishing becomes uneconomic. Recreational fishers are the reason why many areas around Tasmania have been almost completely stripped of rock lobster and other target species.
Finally, this situation further highlights the need for a proper system of comprehensive, adequate and representative no-take marine national parks. These will protect large breeding rock lobsters and might be expected to assist recruitment, although this is difficult to demonstrate scientifically. One benefit of marine national parks that is easy to demonstrate is the way they can act as unfished reference areas. A comparison between areas closed and open to fishing activities allows an assessment of fishing impacts to be made and informs fisheries management. As climate change becomes an issue, these reference areas will also allow fishing impacts to be distinguished from those due to changing water temperature.
It is clearly time for the Tasmanian Government to act to protect the rock lobster fishery as a valuable resource and Tasmania’s marine environment upon which this and other fisheries depend. The TCT has been pointing out these issues for many years. Managers and many fishers should be aware of these problems as well. Some solutions are obvious and can be implemented very quickly; others will need to be developed with input from scientists, managers, commercial and recreational fishers as well as other stakeholders. However, there is no reason why the Tasmanian Government should not begin to address those issues immediately.
Tasmanian Conservation Trust