Trials of oceanographic data collection on commercial fishing vessels in SE Australia
Australia’s fisheries span a large area of ocean. Australia has the world’s third largest Exclusive Economic Zone (EEZ), with an area of over 8 million km2. This zone contains mainly Commonwealth managed fisheries, with State jurisdictions mainly in coastal waters up to the 3 nautical mile limit. Australia's total wild-catch fisheries gross value of production is $1.6 billion, of which 28% is from Commonwealth fisheries and 72% from the smaller coastal inshore fisheries managed by state jurisdictions. The wildcatch fisheries sector employs about 10,000 people across Australia (https://www.awe.gov.au/abares/research-topics/fisheries/fisheries-and-aquaculture-statistics/employment).
The commercial fishing industry has a network of thousands of vessels working mainly in inshore waters around Australia. They can supply a potential platform for extensive and fine scale spatial and temporal monitoring of the waters of the continental shelf (0-1200m), from the surface to the ocean floor. Given that their livelihoods depend on it, they have a keen understanding of oceanographic conditions with respect to fish behaviour, feeding and spawning and the various oceanographic factors that may influence this. In some fisheries (e.g. surface tuna longlining), fishers eagerly seek and use readily available fine-scale oceanographic data such as sea surface temperature and sea level, to improve their targeting and achieve higher resultant catch rates. For many other fisheries, however, it is the fine-scale sub-surface oceanographic conditions (feed layers, thermoclines, temperature at depth etc) that have a critical influence on their fishing dynamics. Unfortunately, this type of oceanographic data is far less readily available. Although fishers and scientists know these factors are important, the time series of fine scale spatial and temporal data relevant to fishery operations is not available to include in stock assessments. As a result, it is often assumed that variations in catch rates reflect changing stock abundance, when it may simply be a result of changing oceanographic conditions.
Marine scientists collect a vast range of oceanographic data using satellites, subsurface drones, and static and drifting buoys. Sea surface data, however, is much easier and more cost-effective to collect at high spatial and temporal resolutions than sub-surface data. Hence, understanding of sub-surface oceanographic conditions tends to be derived from modelling more than actual measurement. This may be sufficient at a wide-scale global or continental level, but it is not adequate at the fine-scale spatial and temporal resolution required for fisheries management.
The use of commercial fishing gear as a research data platform has been increasing in popularity internationally (https://www.frontiersin.org/articles/10.3389/fmars.2020.485512/full). A number of groups in Europe have been doing this for a decade (e.g Martinelli et al 2016), and New Zealand are also now involved (https://www.moanaproject.org/te-tiro-moana). However, this approach has yet to be implemented in Australia in a coordinated way. In particular, our approach dictates open access data served through the IMOS Australian Ocean Data Network (www.aodn.org.au) that can be collected once and used many times.
In this project we intend to instrument seafood sector assets (e.g Trawl Nets, longlines, pots) with fit-for- purpose quality-controlled (QC'd) temperature/pressure sensors to increase the sub-surface temperature data coverage around Australia’s shelf and upper slope regions (0-800m) at low cost. Not only will this assist in the collection of data at relevant spatial and temporal scales for use by fishers, but it will also provide a far more extensive level of QC’d data to oceanographers in near real time (NRT) for evaluation and ingestion into data-assimilating coastal models that will provide improved analysis and forecasts of oceanic conditions. In turn, this will also be of value to the fishing sector when used to standardise stock assessments.
Martinelli, M., Guicciardi, S., Penna, P., Belardinelli, A., Croci, C., Domenichetti, F., et al. (2016). Evaluation of the oceanographic measurement accuracy of different commercial sensors to be used on fishing gears. Ocean Eng. 111, 22–33. doi: 10.1016/J.OCEANENG.2015.10.037
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Understanding factors influencing undercaught TACs, declining catch rates and failure to recover for many quota species in the Southern and Eastern Scalefish and Shark Fishery
Despite the indicators of improvements in fish stock status for SESSF species, the fishery as a whole is failing to catch the TACs of many quota species. Moreover, catch rates for many quota species are continuing to decline despite the historically low levels of fishing effort. The fishery is not in an economic position where it can afford to operate below potential - this under catch equates to a considerable lost opportunity in both the financial value and the volume of fish available for the consumer. Net economic returns for the CTS have recently fallen to $1.4 million in 2013–14, the lowest level since the buyback. NER in the GHaT has been negative since 2008–09. Recent economc analyses (Pascoe pers comm) have revealed that if all vessels could catch the full recommended quota, revenues of the CTS would more than double, while the GHaT revenues would increase by around 24%. For the CTS, average vessel profits are likely to increase by between $200k and $500k, with an average increase of around $380k.
So, what is the cause of the current situation in the SESSF?
There are a variety of different reasons given for the SESSF's TAC undercatch, depending on who you talk to. Anecdotally, it has variously been attributed to reduction in fleet fishing capacity, effort reduction, legislative barriers, spatial closures, changed behaviour of operators, market factors, quota ownership and trading, cost of production, changes in catch per unit of effort, climate change and its impact on oceanographic conditions and potential range shifts of species. It is also quite likely that it is a combination of a number of the above factors.
What can be done?
With such a wide range of potential reasons, it is difficult to determine what further work is required to potentially address these issues in the SESSF. This project centres on development of background papers on each of the issues that will be presented at a workshop designed as the first step in clarifying stakeholder views on the underlying reasons and how they might be resolved in the future.
Final report
Concerns about the ecological and economic sustainability of Australia’s Southern and Eastern Scalefish and Shark Fishery (SESSF) prompted major structural readjustment of the fishery in 2006 that significantly reduced the number of operators in demersal trawl, Danish seine and gill net sectors of the fishery. A decade later, many of the ecological sustainability issues have been addressed and despite declining Gross Value of Production (GVP), there has been variable but overall improvement in net economic returns (NER) of the fishery. There remains, however, a number of indicators in the fishery that may point to significant sub-optimal performance in terms of stock sustainability and fishery profitability as outlined below.
At the end of the 2015/16 year, 23 of the 34 species groups under TACs were less than 50% caught. Of the major quota species, only four had catches above 80% of the TACs (Flathead, Gummy Shark, Pink Ling and School Whiting).
There has been a continual decline in catch rates for many quota species with a range of life histories. Similar trends in decline over the last two decades have been observed for Jackass Morwong, Redfish, Blue Eye Trevalla, Silver Warehou, Blue Warehou, John Dory and Ribaldo, despite the lowest historical effort and catch levels in the fishery. Unstandardised CPUE across the fishery has declined for several years hitting an all-time low in 2015 and has remained at this level in 2016. Moreover, optimised CPUE standardizations for 23 species (including grouped species) and 43 different stocks, methods, or fisheries revealed 29 of the 43 SESSF stocks were found to have declining standardised catch rates.
Historically overfished species (Eastern Gemfish, School Shark, Blue Warehou and most recently Redfish) have shown little sign of recovery despite over a decade of the lowest catches on record resulting from significant management changes under relevant rebuilding strategies
(including bans on targeting, implementation of industry driven avoidance measures, and implementation of spatial closures). The overfishing and subsequent recent recovery of the eastern Orange Roughy stock over the last two decades is well documented – but it is an exception.
There are many and varied reasons to explain these issues in the SESSF, but there has been no attempt at a coordinated approach to identify which factor/s may be the cause, much less how these may be addressed. This project was designed to start this process.