Fisheries and the environment

Assessment report of the Tasmanian Rock Lobster Fishery

Principle 2: Fishing operations should be managed to minimise their impact on the structure, productivity, function and biological diversity of the ecosystem
Department of the Environment and Heritage, December 2001
ISBN 0 642 54859 5

Objective 1: The fishery is conducted in a manner that does not threaten bycatch species.

Information requirements

Species-specific bycatch information is collected as part of the fishery-independent survey. Bycatch information is not recorded by fishers on logbooks, although some anecdotal information is available. Anecdotal information accords with sampling data and suggests that the sampling data may be indicative of the bycatch in commercial operations. The submission states that bycatch in the fishery is low, and a study by Frusher and Gibson (cited in the submission) suggest over 80% of potential bycatch can escape through escape gaps.

The lobster pot fishing method generally is considered to take little bycatch relative to other fishing methods.

Temporal or spatial variations in bycatch (species, quantities, stages of life cycle) may not be available from the limited sources currently available, and it maybe useful to obtain both fishery dependent and fishery independent data over a range of sites and at various times during the fishing season.

Assessment

The assessment of bycatch is based on fishery-independent sampling surveys and anecdotal information, and a study by Frusher and Gibson into bycatch in research and commercial pots sampled in three main locations around Tasmania (Frusher and Gibson, 1992). There appears to be no structured mechanism for obtaining fishery-dependent bycatch data.

Although the fishery regime does not demonstrate robust knowledge of the capture of non-target species in the fishery and its implications, analysis of existing data suggests bycatch is not high. This would be in keeping with the general view that bycatch in rock lobster pots is low relative to other fishing methods.

Some analysis of potential total take has been done by extrapolating sampling survey results, because sampling pots do not have escape gaps and would be expected to take what bycatch is possible with a lobster pot. The results suggests escape gaps (the primary bycatch management strategy) are about 80% effective in significantly reducing bycatch of most finfish and invertebrates, but may not be effective for large species such as draughtboard sharks. The submission does not indicate whether bycatch varies between locations and between seasons, although the study by Frusher and Gibson suggests there is some regional and depth variation in catch rates of wrasse and leatherjackets. Some bycatch species, such as wrasse, leatherjackets and giant crabs, also are taken in other fisheries. Frusher and Gibson suggest that the potential harvest of wrasse from rock lobster pots is only slightly less than the commercial harvest, and conclude that "bycatch of commercial finfish species is significant relative to volumes harvested by targeted fishing".

As the impact is believed low and many species can be returned to the water alive, no specific risk assessments have been conducted on individual bycatch species. Anecdotal information supports live release for some species; tag-recapture data for draughtboard sharks suggest they at least may survive one capture. There has been no specific work undertaken on the survival rates of species returned to the water alive; although Frusher and Gibson imply finfish bycatch may be subject to barotrauma, as the majority of commercial rock lobster potting is carried out in water depths of greater than 18m (Frusher and Gibson, 1992), such trauma effects would not be expected for fish without swim bladders (eg sharks) and non-fish bycatch.

Department of the Environment and Heritage notes that some bycatch of sharks - notably draughtboard sharks – is known to occur. While Department of the Environment and Heritage is aware of no conservation concerns regarding draughtboard sharks, Australia is developing a National Plan of Action -Sharks (as required under the International Plan of Action – Sharks, developed through the Food and Agriculture Organisation). Among others, the IPOA-Sharks recommends that national plans aim to facilitate improved species-specific catch and landings data and monitoring of shark catches; and ensure that sharks catches from directed and non-directed fisheries are sustainable. In light of this, at a minimum the bycatch of elasmobranchs should be recorded, however ideally records should be made of landings and mortalities of all bycatch by species.

Management response

Bycatch management relies on the use of escape gaps (note that large species, such as draughtboard sharks, may not be helped by escape gaps), and the capacity in the Living Marine Resources Act 1995 for response should an emergency develop. DPIWE rely on the catch sampling program and anecdotal information from fishers to bring to their attention changes in bycatch species abundance, but the submission suggests that the reliability of this data is unclear. The logbook form provided with the submission does not contain an explicit field in which fishers may record bycatch. The submission indicates that DPIWE assess that the costs of establishing a monitoring program to detect changes in bycatch species would exceed the benefit.

Management does not include the use of decision rules. Two trigger points (to be reviewed after the first 2 years) are applied: a reduction in "standardised total abundance" of bycatch (25% in any year or 50% in any three-year period); and a 30% change in "standardised species assemblage" of bycatch.

Although Department of the Environment and Heritage recognises the constraints on obtaining more useful data on bycatch from any fishery, it would be useful to develop (and refine over time as more bycatch data becomes available) precautionary contingency trigger points and management responses.

As noted under Principle 1, the management regime has no blanket commitment to an immediate course of action should a trigger be reached. This is as much a source of concern for bycatch species as for Jasus edwardsii.

There have been no specific trials of pot designs to reduce bycatch. Given the relatively low levels of bycatch this may be an appropriate management response.

Conclusion

Overall, the available information suggests levels of bycatch are low relative to other fishing methods. Some modification to the management arrangements to address bycatch more specifically would appear to be warranted.

Recommendations

  1. Mechanisms should be developed to ensure better recording of bycatch in the fishery. A more formal assessment of the risks posed to bycatch species should be carried out before the next assessment to confirm assumptions relating to low risk of having a significant impact on species making up the bycatch for this fishery. Risk assessments could include the vulnerability of various bycatch species; a qualitative assessment on survivorship of animals returned to the water; and identification of areas or times of high bycatch incidence.

Objective 2: The fishery is conducted in a manner that avoids mortality of, or injuries to, endangered, threatened or protected species and avoids or minimises impacts on threatened ecological communities.

Information requirements

Marine turtles (specifically leatherback turtles, Dermochelys coriacea) and seals (species unidentified, but likely to be Australian fur seal, Arctocephalus pusillus) are identified as protected species which may interact with the fishery. Bannister et al (1996) indicate that very occasionally whales have been entangled in lobster pot buoy lines, and it is feasible that some interactions with cetaceans may occur in the Tasmanian rock lobster fishery. The same document indicates that the extent of cetacean interaction is likely to be very low, and for this reason Department of the Environment and Heritage does not consider it a significant factor in the assessment of the Tasmanian rock lobster fishery.

Information on turtle interactions is collected in an ad-hoc fashion. The data available suggests incidence of entanglement is very low, however as reporting is voluntary there is a possibility that interactions are not being reported. Few turtle sightings are demonstrated by data collected for draft Turtle Recovery Plan, but the submission indicates that a study in 1998 (Bone, 1998, cited in the submission by DPIWE) suggests the incidence of leatherbacks in Tasmanian waters may be higher than previously thought. These two factors may mean that estimates of entanglement incidence may be underestimated.

Seal data has been collected via a survey of commercial fishers in 2000 (results yet to become available). It is unclear what data on seal interactions has been collected prior to this, but the submission asserts that the data suggest a low level of interactions. Most interactions appear to be the removal of bait savers from pots and predation on undersized rock lobsters which are returned to the water, but juvenile seals may also be caught in the lobster pots. Seal also interact with discarded waste, and fishers are encouraged to bring all waste back to port to reduce such interactions.

Overall, the reliability of data collected on interactions with endangered, threatened or protected species is unclear and although the submission indicates that data collection is likely in the future, the mechanisms by which this is to be achieved is unclear.

There are no listed ecological communities identified in the area of the fishery.

Assessment

The submission indicates that no formal assessments have been done on the impact of the fishery on endangered, threatened or protected species, because of the low levels of interaction. Some understanding of the types of impacts can be obtained through the Tasmanian threatened species handbook (eg entanglement on buoy lines, in bait box straps). No research into impacts on listed species is currently in train.

Shaughnessy indicates that small Australian fur seals interact with the rock lobster fishery by entering the lobster pots to scavenge baits, and that a figure of 24% of tag recoveries (43 of 182 tags deployed) were from juveniles that had drowned in rock lobster pots (Warneke, 1975, quoted in Shaughnessy, 1999). It is unclear whether these occurred in the Tasmanian fishery, or in rock lobster fisheries across south eastern Australia.

The submission suggests that research into MPAs may lead to research on the impact of lobster potting on communities, however this may not be relevant in this fishery as there are no listed threatened ecological communities identified in the fishery area.

Management response

The management approach to mitigating interactions with listed species is to require commercial and recreational fishers to haul pots within 48 hours of setting, and the submission indicates that in practice pots are hauled more frequently than this. Apart from this, no specific mitigation devices are required or apparently used in the fishery.

With regard to seal interaction mitigation, although the submission suggests fishers may introduce seal spike if predation of rock lobster by seals becomes a problem, DPIWE does not make a commitment to the introduction of this device. The submission is unclear on at what stage predation of rock lobster by seals is likely to become a problem, but the implication is that this will be determined by fishers. If so, it may not reflect a common standard. Department of the Environment and Heritage considers that a more precautionary approach, given the recovery of the seal population is likely to result in an increase in interactions, would be for managers to require the use of mitigation devices where such exist. Other measures which may improve management of interactions include development of a code of practice and improvements to the data collection arrangements.

Although threats to Australian fur seals identified in Shaughnessy suggests that "seals are often accidentally drowned in nets and traps", this is not specifically linked to the Tasmanian rock lobster fishery. Similarly, the same document cites Pemberton et al (1992) as indicating that the incidence of entanglement in Tasmanian waters (estimated as 1.9% of the seal population – considered high in relation to the incidence of entanglement of northern fur seals, which is 0.4% of the estimated population). Pemberton et al suggest that this level of entanglement is a potential threat to seal populations, on the grounds that entanglement has been implicated as a causative factor in the decline of northern fur seals (Pemberton et al, 1992). However, the study shows that the primary causes of entanglement found in the course of their study was trawl net and packaging straps; rope of the type used in the rock lobster fishery, while the source of entanglement with the fourth highest percentage of incidence, was significantly less prevalent.

Department of the Environment and Heritage is of the view that management regulations and operational practices (eg limited soak times, the restrictions on time potting implicit in the quota management scheme, area closures, escape gaps) should reduce mortalities of protected species, but may not reduce overall interactions.

With regard to the impact of the fishery on ecological communities, the submission indicates that there are some areas where closures are in place to protect unique habitat and there is some research in train into impacts of lobster potting on giant string kelp. Research also is being conducted on the change in marine reserves since declaration in 1991; while this focused on rock lobsters, not biodiversity per se, it is possible useful information on communities may be derived.

Department of the Environment and Heritage is of the view that the lack of a structured reporting and monitoring program into interactions with protected species may hinder management actions from achieving the objective. Improvements to data collection may occur when logbooks are amended to include information on turtle interactions. In addition, a group has been set up to advise the Tasmanian Minister on fisher/marine farmer interactions with seals, which may generate a better understanding of the level of interactions and mechanisms for addressing unacceptable interactions.

Conclusion

Available information suggests the level of interactions between endangered, threatened or protected species and the fishery is low. Some modification to the management arrangements to address the impact of the fishery on endangered, threatened or protected species would appear to be precautionary.

Recommendation

  1. A structured reporting and monitoring program into interactions with protected species should be developed as high priority. If this program suggests interactions occur more frequently than previously thought, mitigation measures, including trigger and reference points, should be introduced to reduce interactions. DPIWE are strongly encouraged to investigate the use of seal spikes or other appropriate devices as a precautionary measure.

Objective 3: The fishery is conducted in a manner that minimises the impact of fishing operations on the ecosystem generally.

Information requirements

Little information on the impact of the fishery on the marine environment generally has been collected in the past. The little information which has been collected has related to the impact of MPAs. There is no specific information collection program in place. The submission suggests that information obtained through tertiary studies may be useful and a review may be appropriate. DPIWE suggests a program for future data collection for environmental impacts could be developed devised once such a review has been done.

Assessment

The submission indicates that broader marine environment impacts are poorly understood and there has been little research into the effects of fishing on the marine environment. The documentation suggests an analysis should be done into what work has been done in the past 10 years, from which a program for future data collection and management actions may be devised. Information obtained through tertiary studies may be useful and a review may be appropriate.

The combination of the following factors suggest that the fishery is unlikely to have a significant impact on the marine environment generally:

Management response

There are no management actions built into the regime to address the impact of the fishery on the general marine environment. The submission indicates that some will be developed depending on development of an appropriate data collection process. The suggested review of previous work may provide the material from which appropriate management actions can be developed.

The submission indicates that DPIWE commit to a small-scale research into possible impact of baited pots on reefs. Separate research into MPAs may lead to research on the impact of lobster potting on ecological communities.

Conclusion

There is a poor level of understanding of the impact of the fishery on the general marine environment. Given the nature of the fishery, impacts on the sea floor should not be great - the gear used, although bottom-set, is not dragged across the sea floor and would be expected to have little impact on the benthos.

Given the assessed low level of impact an appropriate management approach may be to conduct comparative analysis of fished and unfished areas.

Recommendations

  1. DPIWE should establish a program monitoring fished and unfished areas in the fishery with a view to identifying changes in the wider marine environment which may be a result of the fishery.

References

Bannister, JL; Kemper, CK and Warneke, RM. 1996. The Action Plan for Australian Cetaceans. Australian Nature Conservation Agency, Canberra. 242 pg.

Bone, C. 1998. Preliminary investigation into Leatherback turtle Dermochelys coriacea distribution, abundance and interactions with fisheries in Tasmanian waters. Unpublished report to Department of the Environment and Heritage (project no. SOMS97-06), Parks and Wildlife Service, Tasmania. Cited in Ford, 2001.

Caton, A and McLoughlin, K (eds). 2000. Fishery Status Reports 1999: Resource Assessment of Australian Commonwealth Fisheries. Bureau of Rural Sciences, Canberra. 250 pg.

Gardner, C; Frusher, SD and Eaton, S. 2001. Fishery assessment report: Tasmanian Rock Lobster Fishery 1999/2000. Tasmanian Aquaculture and Fisheries Institute, University of Tasmania. 90 pg.

Ford, W. 2001. Assessing the ecological sustainability of the Tasmanian rock lobster fishery: a report prepared for Department of the Environment and Heritage as required for assessment under guidelines for Schedule 4 listing under the Wildlife Protection (Regulation of Exports and Imports) Act 1982. Department of Primary Industries, Water and Environment.

Frusher, SD and Gibson, ID. 1998. Bycatch in the Tasmanian Rock Lobster Fishery. In Buxton C and Eayres, SE (eds). Establishing meaningful targets for bycatch reduction in Australian fisheries: Australian Society for Fish Biology workshop proceedings, Hobart, September 1998. Australian Society for Fish Biology, Sydney.

Kailoa, PJ; Williams, M; Stewart, PC; Reichelt, R; McNee, A and Grieve, C. 1993. Australian Fisheries Resources. Bureau of Resource Sciences and the Fisheries Research and Development Corporation Canberra. 422 pg.

Pemberton, D; Brothers, N; and Kirkwood, R. 1992. Entanglement of Australian fur-seals in man-made debris in Tasmanian waters. Wildlife Research 19.

Shaughnessy, PD. 1999. The Action Plan for Australian Seals. Environment Australia, 116 pg.

Turner, K and Gardner, C. 2001. Maturity of male rock lobsters. Fishing Today 14 (3).

Warneke, RM. 1975. Dispersal and mortality of juvenile fur-seals Arctocephalus pusillus doriferus in Bass Strait, southeastern Australia. Rapports et Procès-Verbaux des Réunions Conseil International pour l'Exploration de la Mer 169: 296-302. Quoted in Shaughnessy, 1999.

Yearsley, GK; Last, PR; and Ward, RD (eds). 1999. Australian Seafood Handbook. CSIRO Marine Research. 461 pg.

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