Ecosystem and Habitat Interactions
Credit: Matt Testoni
As part of the ecosystem-based management of the Tasmanian Rock Lobster Fishery, NR&E track threatened, endangered and protected species (TEPS) interactions and by-catch through the catch and effort database. Fishers are now required to record species and the nature of interaction in their logbooks to provide greater detail than was available in previous years. However, there is still confusion amongst fishers about what needs to be reported. The current data on bycatch is unsuitable for detailed analysis to provide guidance on the extent of any TEPS interactions.
The risk to TEPS from the operations of the Tasmanian rock lobster fishery is considered low to medium when assessed against the Australian Government Guidelines for the Ecologically Sustainable Management of Fisheries (2nd Edition). This assessment is required under the Environmental Protection and Biodiversity Conservation Act (1999) and reported in the Assessment of the Tasmanian Rock Lobster Fishery August 2016, Commonwealth of Australia (2016). NR&E is in the process of assessing the reporting procedure for TEPS and by-catch.
By-catch information is collected though research trips and also with observers aboard commercial vessels. These fishing trips are identical except that commercial fishers use pots with open escape gaps whereas research close these gaps to increase the number of undersize lobsters in catches. Discard mortality of individuals captured varies between species with very low or no mortality of crabs, draughtboard sharks, conger eels and leatherjackets. Consequently, the species of most impact for by-catch monitoring are wrasse, perch, cod, octopus and leatherjackets, which are also reported under by-product.
Ensuring Monitoring and Management of By-catch in Southern Rock Lobster Fisheries is Best Practice
By-catch is an important issue in fisheries worldwide, with the impacts of fishing activities on non-targeted species and the wider marine environment receiving increasing public attention. Issues such as the potential wastage of resources through discarding of unwanted catch, ecological impacts on non-targeted species, and the possibility of negative impacts on Threatened Endangered and Protected Species (TEPS) have led to an expectation that government and other managers will report on the status and impacts on these species. In order to do this effectively, well designed monitoring programs need to be in place. Effective by-catch monitoring programs allow researchers to understand which species are important as by-catch across a fishery, how the quantity of by-catch is changing through time, and any potential risks to by-catch species.
IMAS researchers have led the most in-depth analysis of by-catch across the entire Southern Rock Lobster Fishery (SRLF) to date, involving researchers, stakeholders and managers across South Australia, Victoria and Tasmania. We use information from independent scientific observer programs and scientific research cruises collected over a period of greater than 15 years to:
(i) Explore the important by-catch species in each state and management zone;
(ii) Conduct a critical appraisal of the current monitoring programs by comparing them to international best practice;
(iii) Help inform a risk assessment for all by-catch species through workshops held in each state involving key stakeholders including researchers, fishers, fisheries managers, scientific observers involved in the monitoring programs, scientific experts and ecologists.;
(iv) Explore quantities and trends in by-catch for species deemed to be at moderate risk from fishing activities.
Important by-catch species in terms of frequency, total number and weight varied across the states and management zones but generally included wrasse, leatherjackets, perch, octopus, crabs (hermit, velvet and giant) and sharks (Draughtboard Sharks in Tasmania and Eastern Victoria, and Port Jackson Sharks in Western Victoria and South Australia). Undersized Rock Lobsters, which are also considered by-catch, formed a large component of the overall bycatch particularly in Tasmania.
The current by-catch monitoring program was assessed against international best standards defined under the United States Tier Classification Scheme developed by the National Marine Fisheries Service. We found that each state managed program fell into a Tier 2 classification out of five possible tiers ranging from 0 to 5. This score was reasonable when comparing the programs in other fisheries given the size of the SRLF. However, areas for improvement in the observer programs were identified and recommendations on how to improve the ongoing monitoring program are made in light of our findings.
The risk assessment found that no by-catch species was at high risk from fishery operations of the SRLF. Species that were identified as having a medium potential risk were a subset of those that are kept as by-product either for consumption, sale or bait. Barotrauma was also identified as a risk factor for some finfish species with swim bladders as these species when brought up from depth may suffer injury or be unable to descend and thus more susceptible to predation. Also, missing life history information for a number of species meant that precautionary higher risk scores were assigned to these species until more information is obtained. Rates of encounter with gear of Threatened, Endangered and Protected Species (TEPS) were found to be low, and consequently direct threats from fishery operations likely to be low; however, ongoing monitoring of TEPS interactions is a necessary component of best practice.
A short list of ten species identified as being more susceptible to risk from the SRLF were given further analyses. These ten species included Draughtboard Shark, a number of leatherjacket species, Ocean Perch, Blue-throat Wrasse and Conger Eel. Analysis of these species and groups allowed for estimates of total catch of these species and trends in catch through time. These estimates provide a baseline for ongoing monitoring and the setting of reference points for management action for these species. Based on the findings of this report, it is recommended that:
- Improvements are made to the observer programs including increasing the number of vessels participating, creation of consistent reporting methods, improved species identification
- Information is collected for by-catch species with missing life history parameters to allow increased confidence in future risk assessments
- Species identified in this report as being of primary or secondary importance as by-catch in the SRLF are prioritised for ongoing reporting and monitoring, with a periodic census of all by-catch species (perhaps every 5 years) used to detect any trends in overall by-catch composition
- Due to the considerable noise in by-catch data, longer-term trends are used as management trigger points
- Further research is conducted into reducing the amount of undersized Rock Lobster
You can read the full report on the spatial overlap by Leon et al. (2019) at the link:
By-product reported is differentiated into bait and product for sale (consumption). By-product is clearly under-reported by the fishery, especially for animals used as bait. For example, research sampling indicates that around 10 t of wrasse are likely to be captured by fishers, yet less than one tonne is reported on average each year as by-product. There is no apparent improvement in rate of reporting between years.
Supply Risk of Bait
A survey was conducted to determine what species are being used for this purpose and explore any risks around future supply. A total of 29 individual fishers were surveyed in Tasmania (TAS) who declared using 8 different species of fish as a bait; however, they declared preference for Blue Mackerel and Jack Mackerel (Scomber australiasicus and Trachurus spp.), Australian Salmon (Arripis spp.), and Barracouta (Thyrsites atun). Most of this bait is sourced from New Zealand (NZ).
The stock status of many of the preferred bait species used in the Southern Rock Lobster Fishery is not available through formal reporting so was classified as unknown, particularly those from NZ. Australian Salmon and some stock assessment areas for Blue Mackerel, Jack Mackerel and Barracouta from NZ are classified as sustainable. We found that fishers preferred a limited number of bait species and that some were being sourced from fisheries with an ‘unknown’ sustainability status and many fishers were concerned about future supply. Insecurity of existing supply means that other bait options need to be explored. Ongoing monitoring of species being used for bait would assist any future third party sustainability accreditation.
Most fishers in TAS felt that the quality of bait has remained stable. This is, when asked to rate their level of concern regarding the risk of bait supply, 62.1% of the respondent declared that they were ‘somewhat concerned’ about the future risk of bait supply. They also declared (52.2%) that they have not considered using alternative baits to this point.
Lobster buyers / processors also tend to be suppliers of bait and interviews confirmed that Blue Mackerel, Jack Mackerel, Australian Salmon, and Barracouta are the preferred bait types in the Southern Rock Lobster Fishery contributing roughly 90% of bait used (M. Blake, South Australian Lobster Company, pers. comm.). A major supplier of Australian Salmon indicated that they had high demand from the Australian bait market (C. Papageorge, Account Manager of United Fisheries LTD in NZ, pers. comm.), and MD Pty Ltd, a major seafood processor and bait supplier on King Island, TAS indicated that they are very concerned about the future supply of bait. A common theme of discussions with bait suppliers was the increasing prevalence of competition from other markets, namely the human consumption market, for fish species that have been traditionally used as bait.
The apparent shortage in bait is a market issue as Australian salmon is abundant in southern Australia but at historically low levels of catch, while Australia’s small pelagic fishery has 10,000s tonnes of uncaught quota allocated each year.
|Blue mackerel |
|New Zealand||Whole||Unknown||MPI (2017)|
|Australian Salmon (Arripis spp.)||Australia||Cutlets / Heads||Sustainable||Stewart et al. (2018)|
|Jack Mackerel (Trachurus spp.)||New Zealand||Whole||Unknown||MPI (2017)|
|Kahawai (Arripis spp.)||New Zealand||Heads||Sustainable / Unknown||MPI (2017)|
|Tiger Flathead (Platycephalus richardsoni)||Australia||Frames||Sustainable||Emery et al. (2018)|
|Atlantic salmon heads (Salmo salar)||Australia||Heads||Farmed|
|Shark heads (unspecified species)||Australia||Heads||Unspecific Species|
Table: Reported bait taxa used in the Southern Rock Lobster Fishery by origin, type, stock status.