Archived page, Recfishwest Submission to the Environmental Protection Authority on the Cockburn Cement "Long Term Shellsand Dredging Owen Anchorage" Environmental Review and Management Program

INTRODUCTION

The impact of dredging and seagrass removal upon fish stocks, recreational fishing quality and the prospect of successfully colonising seagrass by transplantation or other artificial means to offset seagrass loss are the key concerns that Recfishwest has in relation to the Cockburn Cement shellsand dredging activity and long term proposal.

The tone for this ERMP is set by the foreword. The foreword, presumably written by the signatories, adopts a challenging and almost aggressive tone. Not only is this likely to alienate many readers; but it is quite inappropriate in a document which should strive for scientific integrity. Two inferences in respect to the key issues are made in this tone. They are:

• That there is not a close link between seagrasses and fisheries

• That meadow forming seagrasses can be transplanted

Recfishwest contends that these important statements are incorrect, misleading or at best preliminary and unable to be supported by the information presented in the ERMP.

Recfishwest challenges the ERMP's conclusions in relation to these issues and consequently the foundation of Cockburn Cement's case in support of continued and expanded shellsand dredging activities

Recfishwest has importantly identified two principal and overriding objections to Cockburn Cement's Long Term Shellsand Dredging proposal.

The objections are that the proposal, as identified in the ERMP itself, fails to meet both the requirements of the Ministerial Condition 6-2, August 1994 "that seagrass can be successfully rehabilitated", and the requirement (reinterpreted in 1995), "that due to Cockburn's shellsand dredging operations on Success Bank in Owen Anchorage, there be no net loss of present ecological and cultural function in the Cockburn Sound/Owen Anchorage area." (Supplement to EMP, and referenced in EPA Bulletin 901, August 1998)

LINK BETWEEN SEAGRASSES AND FISHERIES

The foreword and synopsis of the ERMP contain a number of related statements in respect to the link between seagrasses and fisheries and the fisheries of Owen Anchorage. These include

• That the seagrasses of Owen Anchorage do not support any commercial or recreational fishery and that the Seaway will not influence any commercial or recreational fishery in the area.

• That the previously often enunciated view that there is a close, direct link between seagrasses and fisheries is a generalisation only and that the views of scientists are changing (in this regard) as the work is presented at conferences, lectures and in refereed journals"

Recfishwest wishes to address each of these statements:

1. That the seagrasses of Owen Anchorage do not support any commercial or recreational fishery.

Whilst recreational fishers may more often frequent reef or rocky sites in the area, Recfishwest consider there to be significant recreational fisheries on the seagrass banks of Owen Anchorage

Personal observation by many fishers indicates that herring, King George Whiting and squid are all caught in the seagrass areas of Owen Anchorage proposed for dredging. These are some of the most important recreational fish targeted in Metropolitan coastal waters.

It is recognised that this statement conflicts with the results quoted in Table 3.12 on p60. Recfishwest was initially very concerned that the results of the surveys carried out to test the value of seagrass for commercial or recreational fish species failed to find evidence that these fish were present in substantial numbers in the area.

However we now believe that the ERMP survey results are a direct consequence of inappropriate survey techniques employed.

The principle sampling equipment used was the beam trawl, which is commonly used for sampling slow moving or stationary organisms such as prawns or scallops. We contend that it is a largely inappropriate fishing method or sampling technique for most fish species and certainly the fish species of importance to recreational fishers. The majority of fish species will be disturbed by the approach of a beam trawl and/or easily capable of evading capture. Given this survey bias the survey results (that the only species caught were Estuarine catfish, squid, Octopus, Cuttlefish, King prawn and Blue manna crabs) is therefore not surprising. They are all either slow moving or sedentary species.

The only other sampling equipment employed was purse seine netting.

Fisheries sampling programs, which are principally aimed at assessing relative abundance and species mix, rely upon a random or predetermined survey design to minimise bias. However the purse seine technique typically relies upon conscious searching to locate fish schools which are then strategically encircled. If random or predetermined survey designs were employed then it would be highly unsuccessful in capturing fish and would generally result in a non-representative or underestimate of abundance.

Further, purse seine nets operate by enclosing a body of water and typically do not come into contact with the sea floor. Demersal species will not be captured. It is therefore not surprising that the only species caught by this method were Australian herring and Blue sprat as they are both pelagic schooling species

Although we are not aware of the specific design of the purse seine nets used we have been informed (M.Holtz pers.comm.) that the purse seine nets used did make contact with the sea floor facilitating sampling of demersal or benthic species. However despite this advice we believe that the standard haul net would have been significantly more effective in the capture of demersal or benthic species

For the above reasons we contend that the type of fishing gear used in the ERMP sampling program was inappropriate, or at the least not optimal, for sampling fish species, particularly those species found in a seagrass or demersal habitat.

Recfishwest finds it astonishing that the customary fishing techniques adopted for fisheries research of this nature have not been used, or not reported as having been used, in the ERMP surveys. The types of sampling equipment most often used to obtain data relevant to forming survey information such as in this ERMP include surface to bottom haul nets, lampara nets, gill nets (utilising a range of mesh sizes), fish and/or otter trawls, fish traps and handline.

As a consequence Recfishwest rejects the findings of the ERMP in respect to the fish populations present Owen Anchorage area.

2. That the previously often enunciated view that there is a close, direct link between seagrasses and fisheries is a generalisation only and that the views of scientists are changing (in this regard) as the work is presented at conferences, lectures and in refereed journals.

Recfishwest contends that there is a close link between seagrass and fisheries.

Within the ERMP foreward it is implied that our views are maintained because, simply, they are difficult to change. This suggests that to hold such a view is akin to maintaining "old school thinking" or "conventional wisdom" which has simply been reinforced over time through repetition.

Recfishwest considers this inference to be offensive. We maintain our view based upon a wealth of published scientific research and literature which, although mostly not specific to the Owen Anchorage area, has and continues to conclude that there is a close link between seagrass and fisheries.

For the ERMP to mount a case that such a link is in question and a generalisation only, on the strength of the surveys conducted for the ERMP, is extraordinarily preliminary, and lacks validation or testing by other research programs or existing literature.

The statement in the ERMP foreward that "the views of scientists are changing as the work is presented at conferences, lectures and in refereed journals" is unsubstantiated and clearly a shallow attempt to engender support for the ERMP findings.

In support of Recfishwest's strong belief that there is a close link between seagrass and fisheries we cite the following:

Statements and findings contained within the ERMP.

Although the foreword comments that the link between seagrasses and fisheries was not confirmed in the ERMP studies, those studies report four to five times the biomass of fish in seagrass as opposed to deep sand (p59). In the same section it also reports, "The loss of meadows of A. griffithii and P. coriacea is likely to influence the numbers in the Owen Anchorage region of fish species that prefer those habitats".

The ERMP says that seagrasses do not provide important nursery habitats for juveniles of fish species (p59) although on the same page it says that juvenile fish may occupy P.sinuosa meadows before moving on. The following is a direct quote from the CSIRO Division of Fisheries brochure "Seagrasses":

"Seagrasses play a vital role in the marine food web. The leaves and stems of seagrasses support numerous epiphytes (small seaweeds and animals like seasquirts and sponges that cling to them for support). These smaller organisms are grazed upon by tiny animals such as shrimps and snails. In turn, these animals are eaten by larger fish, rock lobsters and crabs. When the seagrasses decline the links in this productivity chain are broken and the whole ecosystem collapses. Seagrasses also play an important role in the cycling of marine nutrients. Discarded seagrass leaves and the epiphytes they support are broken down by wave action and bacteria and consumed by animals that live off rotting material on the sea bottom. Western rock lobsters are among the animals that forage in this detritus and feed on the nutrient rich material."

Separate evidence is available for King George whiting (Sillaginodes punctata), which is a very important species for recreational fishers. Hyndes, Platell, Potter and Lenanton (1998 Fishery Bulletin 96:258-270) found that on the West Coast this

species essentially occupies three different habitats during the course of its life cycle. They state that any management plan for the species must take into account the need to protect these habitats. These habitats are: sheltered nearshore waters of marine embayments, which are nursery areas for post-larval S. punctata; slightly deeper waters (2-10m) in marine embayments and estuaries used by fish from ca.1.5 years in age and 250 mm in length; then at 350-400mm fish finally move to deeper water at 6-50m near reefs or seagrass beds. The patchy seagrass beds of Success and Parmelia Banks represent the habitat used by the intermediate size fish.

At least in some years of good juvenile recruitment substantial numbers of King George Whiting (circa 30cm length) are present on mixed bare sand / seagrass habitats of these banks (N. Halse pers.comm.)

In recognition of the importance of seagrass in respect to fish and fisheries NSW Fisheries has recently published Habitat Protection Plan No 2: Seagrasses which was gazetted in September 1997 (NSW Fisheries 1997). This plan aims to ensure that there is no net loss of seagrasses within the coastal and estuarine waters of New South Wales, and it prohibits or limits a wide range of damaging activities (such as dredging, reclamation, aquaculture and the construction of wharves and breakwaters) to help protect seagrass habitat.

SOCIAL VALUE

Recfishwest contends that the area where the proposed dredging will take place has a special value for recreational fishers. This particular value arises because commonly sought species can be caught there and because of its close proximity for boat access from Fremantle Harbour, the Fremantle Fishing Boat Harbour, Fremantle Sailing Club, Cockburn Power Boat Club ramp and the Woodman Point boat ramp. The area to be dredged is south west of Fremantle, but it is protected by the reef from the Stragglers to Carnac Is. The protected water and the route home, which is so often down wind from the prevailing wind, makes this fishing location a relatively safe one. This has a special value for people with smaller boats, for older people and for fishing in wintertime.

Further, Recfishwest regards it as self evident that people much more closely identify with and value those things that they can see and hence respond to. There is consequently a major value attached to the visually accessible shallow banks and seagrasses in contrast to the deeper waters including those which have been dredged. This visual amenity, as the contrast of variable light and dark effects occur, is very high and the effect quite beautiful when clear water and bright light combine.

It is no accident that EIS's for significant terrestrial developments routinely require visual impact assessments to be made - the lack of such an assessment in this ERMP is regrettable.

Deeper dredged waters offer no visual focal point. Neither is the average person likely to be convinced that the lost visual amenity has somehow been compensated for by a possible substitution of deeper detritus feeding animals for seagrass with fish species familiar to the average recreational fisher.

ECOLOGICAL VALUE

Recfishwest believes that the calculations of change over time in ecological value are so clearly flawed that it raises questions about the whole ERMP.

The problem arises from the deep sand areas, which have been allocated an ecological value arising from their biogeochemical cycling and their secondary production. As there is little primary production, this activity depends largely on the accumulation of detritus, dead algae and seagrass. Increasing the area of this habitat by dredging will not increase this detritus at all (in fact it will slightly decrease it) and it is doubtful whether the secondary production and therefore the ecological value of the total deep sand habitat will increase very much. Certainly it will not increase in linear relation to the area as appears to have been the basis of the calculations. Reworking Table 4.7 to take account of this gives the following results. In the year 2034 the ecological value of the area would have decreased compared to 1995 as follows:

Neglecting the detritus substrate limitation and using a linear relation - 2.0 % Assuming strict substrate dependence, therefore no increase -10.6% Allowing an intermediate 50% increase - 6.3%

It is interesting to note that the ERMP asserts that the loss of ecological value for the whole Cockburn Sound/Owen Anchorage area from pre 1970s to 1995 was 19.7% and that this would rise to 20.5% at the completion of long term dredging. It goes on to say, "This small change would be extremely difficult to detect." Yet this change is almost exactly the same relative magnitude as the 5% increase in summer flushing rate, predicted to be caused by the Seaway, which is claimed as a significant positive environmental impact.

It is inconsistencies such as this which cause Recfishwest considerable concern and calls into question the objectivity of the information presented.

SEAGRASS COVER

The ERMP confuses natural variation in seagrass cover with the effects of dredging.

Seagrass appears to be dynamic in this area according to the monitoring and for some reason not associated with dredging it increased in area from 1972 to 1995. It is quite invalid, and indeed improper, to assume this increase would carry through to 2034 and that therefore the ecological value at the end of the long term program will be undiminished compared to 1972 (4.4.5, p127). The seagrass might decline again or not; the real issue is the consequences of the dredging.

Dredging permanently makes the area unsuitable for the growth of seagrass.

It is strongly suggested from examination of Figures 3.6 and 3.8 (pp 46-7) that had it not been for past dredging there would have been considerably more increase in seagrass cover between 1972 and 1999. This increase would have been of mixed A. griffithii and P. coriacea across the shipping channel and previously dredged shell sand area of Success Bank.

It is of some concern that Stage 2 of the current proposal is based on the premise that the area to be dredged on West Success Bank and north of the Mewstones has little or no seagrass. It can be seen from Figure 3.8 that the eastern part of the area previously carried seagrass and all around the area seagrass has been colonising since 1972 and may continue to spread into the proposed dredging area. Dredging this area is precluding natural processes and may well destroy a beneficial natural resource.

Further, it is also very misleading to 'claim' the serendipitous increase in seagrass cover on Success Bank as providing a context in which further mining might be favoured. It could just as easily be claimed that, given the serendipitous increase in cover to the east, the western area should be protected on the grounds of future similar extensions of grass to the western end. The proponent does not consider this surmise.

Recfishwest contends that the mining proposals should be assessed in their own right and not be confused by what might be temporary changes. In this regard, as noted above, the permanent loss of significant areas of potential habitat caused by dredging becomes increasingly untenable as the areas removed from further colonisation potential become proportionally greater.

Recfishwest notes the conclusions of the EPA's Bulletin 901 of August 1998, which include, inter alia, that the EPA has formed the view that "proposals involving the removal of seagrass and potential seagrass habitat in the long-term for shellsand should be recognised as environmentally unreasonable". (emphasis added)

In its response of 2 Sept 1998 to that Bulletin, Recfishwest noted that it would have been preferable to have 'unreasonable' replaced with 'unacceptable', and with the caveats included elsewhere in this submission, Recfishwest continues to hold this view.

SEAGRASS REHABILITATION

The whole issue of seagrass transplanting has become quite academic and unrealistic in practical terms.

The original targets set in 1995 were that 15 months prior to the depletion of the Medium Term resource 1-3 ha of seagrass had to be rehabilitated with 12 month survival and 1 ha had to show evidence of over 3 years survival. In reality, over the

last four years, less than 0.07 hectares of seagrass have been transplanted, 70% of which survived and might cover a potential 0.25 hectares. To save the seagrass in the Stage One Seaway by transplanting it prior to dredging, which was surely the original objective, would take over a thousand years at current rates!

What the ERMP demonstrates is that seagrass can be mechanically transplanted successfully, but that it is not feasible to do it on a large scale. Whether it is useful to continue work on broader aspects of seagrass revegetation is a different matter. Recfishwest also has doubts about the value of this.

Where seagrass has been destroyed in Western Australia it is because of high nutrient/low light penetration (eg. Cockburn Sound), the water has been dredged and will be too deep (eg. shell sand dredging), or the water body has been turned into an industrial plant and will be too saline (eg. Shark Bay Salt development). All of these things temporarily or permanently prevent seagrass growth. Recfishwest questions the purpose of revegetation in such contexts.

We note again the conclusions of Bulletin 901, which, in this matter stated "that the EPA has concluded that the environmental harm resulting from the mid-term proposal by Cockburn Cement is outweighed by the environmental value flowing from the research being undertaken provided the commitment to research is accompanied by a condition towards utilising the research findings for continuous improvement in environmental performance, both during the period of the Medium-term dredging proposal and post dredging." (emphasis added)

It is clear that a program meeting such a commitment has not been able to be realised from the results of the research undertaken.

Unless there can be shown to be new and promising lines of research, Recfishwest suggests that the mechanical transplanting program should be terminated on the grounds that most worthwhile results have already been accrued. We believe that it is likely that the continuing program as envisaged by the ERMP simply provides a superficial cover for the developer's continuing interests.

CHANGES TO WAVE ACTION AND SEDIMENT TRANSPORT

The ERMP raises numerous unanswered questions in relation to the impacts of the increase in wave action arising from the proposed dredging.

One striking example is contained within the Executive Summary (p 10); "The nature and shape of Success and Parmelia Banks will be unaffected by dredging except during severe storm events ". This leaves the reader to wonder what will happen in the severe storm event! Recfishwest was not able to find the answer to that question in the rest of the document; but it should be answered.

Similarly, if there are adverse impacts of the changed wave climate around the Explosives jetty, what precise commitment does Cockburn Cement make?

One impact of the changing wave climate as a result of proposed dredging is that sediment transport rates will rise on Success and Parmelia Banks on the east side of the Seaway. The ERMP is silent on what effect this might have. As the sites predicted to be affected (sites 10 and 15 in Fig, 4.8 on p103) appear to have seagrass cover at present, it is possible that the sediment transport rates (Table 4.2) may be beyond the capacity of the seagrass beds and they may be destroyed. The impact of dredging on seagrass in Table 4.1 does not appear to take this possibility into account and it could result in a further loss of seagrass with further impact on ecological value. This requires more information from the proponent.

WATER CLARITY

The expected impacts on water clarity are negative. These include some impact from the increased winter wave activity in Cockburn Sound and an increase in turbidity plumes. The ERMP says the plumes from the dredge and the onshore washing plant are not expected to change from existing levels; but as production is anticipated to increase by more than 50% over the next 20 years this seems unlikely. Water quality, particularly clarity, is one of the main problems in Cockburn Sound and therefore this is a critical issue. When the dredging is occuring on Parmelia Bank any southward drift of a turbidity plume directly affects Cockburn Sound and could significantly reduce the photosynthetic zone which could further impact on seagrasses. The company should be challenged on the issue of water quality impacts.

NEED FOR A SEAWAY

The proponent strongly emphasises the alleged 'good' that arises from the 'free' dredging of a new 'seaway'. Recfishwest is not aware of there ever having been strong calls for such a facility from any maritime interests although we do recognise that a properly maintained second channel might have some economic and strategic benefits.

It is our strong position that any benefits arising from an unnecessarily wide second channel would be comprehensively outweighed by the resultant environmental losses. Further, all current maritime interests, including the RAN have predicated their operations on the basis of existing infrastructure as opposed to what, would have been seen, and still should be seen, as an opportunistic concept for a 'seaway'.

It would be far better from environmental and socio-economic perspectives to give consideration to either widening the existing channel or creating a second channel through the previously dredged area of Parmelia Bank, or both. This would have the effect of providing the state with the economic benefits claimed by the proponent for the seaway while minimising environmental impacts potentially arising from the increased water flows which would arise from such a seaway.

ALTERNATIVES TO DREDGING

The key question posed by this ERMP is whether comprehensive and genuine attempts will be made to find an alternative shellsand source or do we continue to dredge shellsand in metropolitan waters with the inevitable result of the loss of virtually the entire Owen Anchorage shallow water ecosystem?

Although the predictions from Cockburn Cement indicate that a large and increasing proportion of shellsand is required for lime production, there is nevertheless a substantial amount used for cement production. We are not able to verify the company's predictions for proportions of high grade lime; but nevertheless it is clear that if the basic material for cement production (a readily available and commonly traded material) is sourced elsewhere then the demand on the environmentally sensitive shell sand resource would be reduced.

Extending the rights of Cockburn Cement to dredge shell sand from the Owen Anchorage area for another 23 years beyond 2011 is a very big commitment for any government to make on behalf of the community it represents and not one Recfishwest believes should be made.

If such extension is not given, presumably on EPA advice, then all the state has to do under the Agreement Act is to use every endeavour to find other resources. The state may adopt the position that in the better interests of Western Australia, a less convenient and more costly alternative may have to be adopted.

Cockburn Cement has asserted that alternative resources of high-grade calcium carbonate are not available. Certainly Recfishwest can not claim expertise in this field. However we have endeavoured to obtain the "State Limestone Strategy" (or some similar title) from the Department of Resources Development and have been told that the report is not yet available in final form. This seems singularly ill timed in relation to the current ERMP assessment.

We have endeavoured to pursue this matter further and have identified three possible sources in addition to Dongara and Owen Anchorage. These are the Boranup dune, Cape Range and the Nullabor limestone. The first source would be limited and may involve environmental problems; the second has environmental problems; however the Nullabor limestone is certainly promising as it also has the advantage of full rail access from source to manufacturer.

We have been advised that the Nullabor resource has a very high lime content (Don Martin, DRD, personal communication). We recognise that there would be additional transport costs and the Cockburn Cement plant may have been designed for a different material; however Recfishwest is concerned that investigation of this and other potential options as realistic long-term sources were not identified and discussed in the ERMP.

There is now less than two more year's lead-time to the end of the medium-term proposal in which to find a solution to this problem. If a solution is not found and the current ERMP is approved (Recfishwest would consider such an outcome to be absolutely unacceptable), then Cockburn Cement and the State will encounter the same problem in 2034. We anticipate that community attitudes will have evolved to such an extent by that time so as to preclude continued dredging operations in Cockburn Sound.

This absurdity is emphasised by CCL's own acknowledgement regarding the 'greater' environmental values of east Success Bank. There is no suggestion in the ERMP that East Success Bank should be given any reserve status, let alone A class status. Therefore when this area is the last remaining source of high grade shellsand, and assuming there has still been no reasonable source of alternative resources identified then the prospect of focusing on East Success Bank may once again arise.

Recfishwest is very disappointed that little headway has been made in developing alternatives to shellsand mining in Owen Anchorage. We believe that this slow progress has largely resulted from CCL not being committed to the development of such alternatives as Owen Anchorage has provided a very cheap source high quality lime with the promise of further to come.

Recfishwest understands that there is a benefit to State/society in having convenient access, as has been the situation in the manufacturing of lime/cement for many years.

We further understand that developing alternative resources may well come with an additional economic cost, as is indicated in the ERMP. However we believe that this cost will be significantly outweighed by the greater benefit of reserving the remainder of the shallow waters for future generations as an excision from the State Agreement Act and gazetted as an "A" class reserve.

Recfishwest believes that the time has now come to draw the line. The environmental values cannot continue to be compromised in favour of economic values to the point that irrecoverable damage and impacts have been produced.

Recfishwest recognises however, that it will be unrealistic to have CCL cease mining operations in 2002 at the end of the medium-term approvals. Accordingly a compromise has to be found to allow a reasonable phase-out period.

PRINCIPLE OBJECTIONS

Recfishwest has challenged the ERMP's conclusions in respect to a number of issues and believe that the foundation of Cockburn Cement's case in support of continued and expanded shellsand dredging activities is untenable.

In addition Recfishwest has importantly identified two principal and overriding objections to Cockburn Cement's Long-Term Shellsand Dredging proposal.

The principle objections by Recfishwest to the proposed long-term shell sand dredging by Cockburn Cement are:

The very specific argument that the proposal as set out in the ERMP does not meet the requirements of the Ministerial Condition 6-2, August 1994, "that seagrass can be successfully rehabilitated, or that its dredging would have acceptable ecological and wave climate consequences". The "acceptable consequences" was interpreted in 1995 as, "that due to Cockburn's shell sand dredging operations on Success Bank in Owen Anchorage, there be no net loss of present ecological and cultural function in the Cockburn Sound/Owen Anchorage area."

Recfishwest contends that firstly seagrass cannot be successfully rehabilitated after dredging. The water is too deep and the light attenuation too great. In practice Cockburn Cement has not been able to carry out seagrass rehabilitation anywhere at a rate even approaching the rate of dredging. Specifically, it has not met the targets set for the program in 1995 (ERMP p85, paras 2 and 3).

Recfishwest contends that secondly there will be a loss of ecological function. There is a loss of ecological value between 1995 and 2034 of 2.0% using the proponent's own figures. However Recfishwest contends that this table seriously underestimates the loss of ecological value and that the real loss will be much higher.

CONCLUSIONS

1. It is the position of Recfishwest that the Cockburn Cement Long-Term Dredging proposal be rejected.

2. That Shellsand dredging in Owen Anchorage be phased out within a reasonable timeframe with CCL having to provide a statement of support as to which areas it wishes to access for this period. This statement must be available for community consultation and, at minimum, by way of a Public Environmental Review.

The PER should give deep consideration to the benefits and costs associated with either a reasonable widening of the existing shipping channel or the construction of a 'narrow' (vis a vis seaway) second channel through the previously dredged area of Parmelia Bank, or both.

3. That the remaining areas of Parmelia and Success Banks must be given formal reserve status, preferably A class.



This page last updated on 30 December 2003.