Rohan Currey
I’m a marine biologist and fisheries scientist with two decades of experience at the science-policy interface. I’ve worked in the UK for a global ocean charity – the MSC – and before that I worked for New Zealand Government, representing NZ at the IWC and CCAMLR. I hold a PhD in marine mammal science with a research background in cetacean population biology, ecology, mark-recapture analysis, population viability analysis and risk assessment.
less
Related Authors
InterestsView All (14)
Uploads
Papers by Rohan Currey
This update has been developed by the Science Team within the Fisheries Management Directorate of the Regulation and Assurance branch, Ministry for Primary Industries (MPI). It does not cover all issues but, as anticipated, includes more chapters than previous editions. As with the Reports from Fisheries Assessment Plenaries, it is expected to change and grow as new information becomes available, more issues are considered, and as feedback and ideas are received. This synopsis has a broad, national focus on each issue and the general approach has been to avoid too much detail at a local, fishery, or fishstock level. For instance, the benthic (seabed) effects of mobile bottom‐fishing methods are dealt with at the level of all bottom trawl and dredge fisheries combined rather than at the level of a target fishery that, although it might be locally important, might contribute only a small proportion of the total impact. The details of benthic impacts by individual fisheries will be documented in the respective chapters in the May or November Report from the Fisheries Assessment Plenary, and linked there to the fine detail and analysis in Aquatic Environment and Biodiversity Reports (AEBRs), Fisheries Assessment Reports (FARs), and Final Research Reports (FRRs). Such sections have already been developed for several species in the Fishery Assessment Plenary Reports, and others will follow.
The first part of this document describes the legislative and broad policy context for aquatic environment and biodiversity research commissioned by MPI, and the science processes used to generate and review that research. The second, and main, part of the document contains chapters focused on various aquatic environment issues for fisheries management. Those chapters are divided into five broad themes: protected species; non‐ QMS (mostly fish) bycatch; benthic effects; ecosystem issues (including New Zealand’s oceanic setting); and marine biodiversity. A third part of the review includes a number of appendices for reference. This review is not yet comprehensive in its coverage of all issues or of all research within each issue, but attempts to summarise the best available information on the issues covered. Each chapter has been considered by the appropriate working group at least once.
CCAMLR is the 25-Member organisation responsible for the conservation and management of marine living resources in the Southern Ocean. The CAMLR Convention Area includes all waters south of the Antarctic Convergence and covers around 10 percent of the Earth’s surface.
Under the Convention, CCAMLR is required to maintain ecological relationships between harvested, dependent and related populations, and to prevent or minimise the risk of changes in the marine ecosystem that are not potentially reversible over two or three decades.
In its Convention Area, CCAMLR manages fisheries that target Antarctic krill (Euphausia superba), mackerel icefish (Champsocephalus gunnari), Patagonian toothfish (Dissostichus eleginoides) and Antarctic toothfish (Dissostichus mawsoni). Antarctic krill and mackerel icefish are not currently fished in the Ross Sea.
An exploratory fishery for toothfish, primarily Antarctic toothfish, has operated in the Ross Sea since 1997. In the 2015 stock assessment, toothfish spawning stock biomass in the Ross Sea was estimated at ca. 71% of unfished levels, well above the target level of 50% that was set to ensure the stock maintains stable recruitment.
Toothfish Predators: In the Right Place at the Right Time
While toothfish remain relatively abundant in the Ross Sea, we are only beginning to understand their ecological relationships, in particular their potential importance as a prey species for predators such as Antarctic killer whales (Orcinus orca) and Weddell seals (Leptonychotes weddellii).
Toothfish spend much of their lives at depths (>1000m) that would prohibit foraging by many air breathing predators. However in key locations on the Ross Sea shelf, toothfish are found at depths (~600m) that are more accessible to diving predators. When these locations become ice-free in the austral summer, killer whales and Weddell seals are able to access these potential prey. Photo ID and satellite tagging data obtained by New Zealand and Italian researchers confirms that killer whales move from as far as the Kermadec Islands and northern New Zealand to the Ross Sea shelf, and the availability of a prey source like toothfish may well be a key factor.
Maintaining Ecological Relationships and Minimising Risk
For CCAMLR to ensure that it maintains the ecological relationships between toothfish and its predators, CCAMLR needs to understand these ecological relationships and then manage the toothfish fishery such that it minimises the risk of ecosystem changes.
Localised reductions in toothfish abundance in key areas such as the Ross Sea shelf may reduce prey availability for toothfish predators, as there appears to be no alternative fish prey in the Ross Sea that could adequately replace toothfish.
Marine mammal depredation of toothfish longlines, common in some CCAMLR fisheries, has not been observed in the Ross Sea. If killer whales learn to depredate toothfish longlines in the Ross Sea, or develop this behaviour elsewhere and then apply it in the Ross Sea, this may result in ecosystem changes that are unlikely to be reversible within two or three decades.
Proposal for a Ross Sea Region Marine Protected Area
To reduce the risk of such changes (and to address other objectives), CCAMLR is currently considering a joint New Zealand-United States proposal for a Ross Sea region Marine Protected Area4. The MPA proposal provides a mechanism for ensuring spatial segregation between fishing effort and key foraging areas for toothfish predators. If the MPA proposal is adopted, important areas such as the Ross Sea shelf would be closed to toothfish fishing.
If adopted, the Ross Sea region Marine Protected Area would be the world’s largest MPA, encompassing 1.55 million square kilometres, of which 1.02 million square kilometres would be no-take. Integral to the MPA proposal is a comprehensive research and monitoring plan that seeks to encourage collaborative research by all CCAMLR Members in the Ross Sea. This would involve establishing long-term multi-disciplinary studies in collaboration with international partners to characterise the ecological relationships of toothfish, its predators and prey.
This update has been developed by the Science Team within the Fisheries Management Directorate of the Regulation and Assurance branch, Ministry for Primary Industries (MPI). It does not cover all issues but, as anticipated, includes more chapters than previous editions. As with the Reports from Fisheries Assessment Plenaries, it is expected to change and grow as new information becomes available, more issues are considered, and as feedback and ideas are received. This synopsis has a broad, national focus on each issue and the general approach has been to avoid too much detail at a local, fishery, or fishstock level. For instance, the benthic (seabed) effects of mobile bottom-fishing methods are dealt with at the level of all bottom trawl and dredge fisheries combined rather than at the level of a target fishery that, although it might be locally important, might contribute only a small proportion of the total impact. The details of benthic impacts by individual fisheries will be documented in the respective chapters in the May or November Report from the Fisheries Assessment Plenary, and linked there to the fine detail and analysis in Aquatic Environment and Biodiversity Reports (AEBRs), Fisheries Assessment Reports (FARs), and Final Research Reports (FRRs). Such sections have already been developed for several species in the Fishery Assessment Plenary Reports, and others will follow.
The first part of this document describes the legislative and broad policy context for aquatic environment and biodiversity research commissioned by MPI, and the science processes used to generate and review that research. The second, and main, part of the document contains chapters focused on various aquatic environment issues for fisheries management. Those chapters are divided into five broad themes: protected species; non- QMS (mostly fish) bycatch; benthic effects; ecosystem issues (including New Zealand’s oceanic setting); and marine biodiversity. A third part of the review includes a number of appendices for reference. This review is not yet comprehensive in its coverage of all issues or of all research within each issue, but attempts to summarise the best available information on the issues covered. Each chapter has been considered by the appropriate working group at least once.
• to evaluate EM and methods of implementing automatic collection of at-sea fisheries data;
• to compare data collected by EM reviewers and at-sea observers; and
• to evaluate the needs of an operational program for the use of EM within the inshore Set Net fishery.
This update has been developed by the Science Team within the Fisheries Management Directorate of the Resource Management and Programmes branch, Ministry for Primary Industries (MPI). It does not cover all issues but, as anticipated, includes more chapters than in 2011 and 2012. As with the Reports from Fisheries Assessment Plenaries, it is expected to change and grow as new information becomes available, more issues are considered, and as feedback and ideas are received. This synopsis has a broad, national focus on each issue and the general approach has been to avoid too much detail at a fishery or fishstock level. For instance, the benthic (seabed) effects of mobile bottom-fishing methods are dealt with at the level of all bottom trawl and dredge fisheries combined rather than at the level of a target fishery that might contribute only a small proportion of the total impact. The details of benthic impacts by individual fisheries will be documented in the respective chapters in the May or November Report from the Fisheries Assessment Plenary, and linked there to the fine detail and analysis in Aquatic Environment and Biodiversity Reports (AEBRs), Fisheries Assessment Reports (FARs), and Final Research Reports (FRRs). Such sections have already been developed for several species in the 2012 and 2013 Fishery Assessment Plenary Reports, and others will follow.
The first part of this document describes the legislative and broad policy context for aquatic environment and biodiversity research commissioned by MPI, and the science processes used to generate and review that research. The second, and main, part of the document contains chapters focused on various aquatic environment issues for fisheries management. Those chapters are divided into five broad themes: protected species; non-QMS fish bycatch; benthic effects; ecosystem issues (including New Zealand’s oceanic setting); and marine biodiversity. A third part of the review includes a number of appendices for reference. This review is not comprehensive in its coverage of all issues or of all research within each issue, but attempts to summarise the best available information on the issues covered. Each chapter has been considered by the appropriate working group at least once.
The panel’s scores combined for all identified threats suggested a broad range of plausible values for human-induced Maui’s dolphin mortalities over the next 5 years (a median of 5.27 dolphins per annum with 95% of the distribution of scores being between 0.97 and 8.40 dolphins per annum). The panel attributed 95.5% of these mortalities to commercial, recreational, customary or illegal fishing-related activities combined, and the remaining 4.5% to non-fishing-related threats.
Despite this uncertainty, the panel’s scores indicate high confidence that total human-induced mortality is higher than the population can sustain. Population projections based on the panel’s estimated total mortalities indicate a 95.7% likelihood that the population will decline if threats remain at current levels (i.e. as at the time of the workshop and prior to the introduction of interim measures). estimated total human-induced Maui’s dolphin mortalities equate to a level of impact that is many times higher than the estimated Potential Biological Removals (PBR; a median of 75.5 times PBR, with 95% of the distribution of estimates being between 12.4 and 150.7 times PBR).
The risk assessment method assessed the cumulative impact and associated population risk posed by all threats combined and also disaggregated the impacts of the respective threats, to identify those threats that pose the greatest risk to the dolphins. It also identified several threats that may have a low likelihood, but which, given the small population size of Maui’s dolphins, nonetheless may have detrimental consequences for the population.
This update has been developed by the Science Team within the Fisheries Management Directorate of the Regulation and Assurance branch, Ministry for Primary Industries (MPI). It does not cover all issues but, as anticipated, includes more chapters than previous editions. As with the Reports from Fisheries Assessment Plenaries, it is expected to change and grow as new information becomes available, more issues are considered, and as feedback and ideas are received. This synopsis has a broad, national focus on each issue and the general approach has been to avoid too much detail at a local, fishery, or fishstock level. For instance, the benthic (seabed) effects of mobile bottom‐fishing methods are dealt with at the level of all bottom trawl and dredge fisheries combined rather than at the level of a target fishery that, although it might be locally important, might contribute only a small proportion of the total impact. The details of benthic impacts by individual fisheries will be documented in the respective chapters in the May or November Report from the Fisheries Assessment Plenary, and linked there to the fine detail and analysis in Aquatic Environment and Biodiversity Reports (AEBRs), Fisheries Assessment Reports (FARs), and Final Research Reports (FRRs). Such sections have already been developed for several species in the Fishery Assessment Plenary Reports, and others will follow.
The first part of this document describes the legislative and broad policy context for aquatic environment and biodiversity research commissioned by MPI, and the science processes used to generate and review that research. The second, and main, part of the document contains chapters focused on various aquatic environment issues for fisheries management. Those chapters are divided into five broad themes: protected species; non‐ QMS (mostly fish) bycatch; benthic effects; ecosystem issues (including New Zealand’s oceanic setting); and marine biodiversity. A third part of the review includes a number of appendices for reference. This review is not yet comprehensive in its coverage of all issues or of all research within each issue, but attempts to summarise the best available information on the issues covered. Each chapter has been considered by the appropriate working group at least once.
CCAMLR is the 25-Member organisation responsible for the conservation and management of marine living resources in the Southern Ocean. The CAMLR Convention Area includes all waters south of the Antarctic Convergence and covers around 10 percent of the Earth’s surface.
Under the Convention, CCAMLR is required to maintain ecological relationships between harvested, dependent and related populations, and to prevent or minimise the risk of changes in the marine ecosystem that are not potentially reversible over two or three decades.
In its Convention Area, CCAMLR manages fisheries that target Antarctic krill (Euphausia superba), mackerel icefish (Champsocephalus gunnari), Patagonian toothfish (Dissostichus eleginoides) and Antarctic toothfish (Dissostichus mawsoni). Antarctic krill and mackerel icefish are not currently fished in the Ross Sea.
An exploratory fishery for toothfish, primarily Antarctic toothfish, has operated in the Ross Sea since 1997. In the 2015 stock assessment, toothfish spawning stock biomass in the Ross Sea was estimated at ca. 71% of unfished levels, well above the target level of 50% that was set to ensure the stock maintains stable recruitment.
Toothfish Predators: In the Right Place at the Right Time
While toothfish remain relatively abundant in the Ross Sea, we are only beginning to understand their ecological relationships, in particular their potential importance as a prey species for predators such as Antarctic killer whales (Orcinus orca) and Weddell seals (Leptonychotes weddellii).
Toothfish spend much of their lives at depths (>1000m) that would prohibit foraging by many air breathing predators. However in key locations on the Ross Sea shelf, toothfish are found at depths (~600m) that are more accessible to diving predators. When these locations become ice-free in the austral summer, killer whales and Weddell seals are able to access these potential prey. Photo ID and satellite tagging data obtained by New Zealand and Italian researchers confirms that killer whales move from as far as the Kermadec Islands and northern New Zealand to the Ross Sea shelf, and the availability of a prey source like toothfish may well be a key factor.
Maintaining Ecological Relationships and Minimising Risk
For CCAMLR to ensure that it maintains the ecological relationships between toothfish and its predators, CCAMLR needs to understand these ecological relationships and then manage the toothfish fishery such that it minimises the risk of ecosystem changes.
Localised reductions in toothfish abundance in key areas such as the Ross Sea shelf may reduce prey availability for toothfish predators, as there appears to be no alternative fish prey in the Ross Sea that could adequately replace toothfish.
Marine mammal depredation of toothfish longlines, common in some CCAMLR fisheries, has not been observed in the Ross Sea. If killer whales learn to depredate toothfish longlines in the Ross Sea, or develop this behaviour elsewhere and then apply it in the Ross Sea, this may result in ecosystem changes that are unlikely to be reversible within two or three decades.
Proposal for a Ross Sea Region Marine Protected Area
To reduce the risk of such changes (and to address other objectives), CCAMLR is currently considering a joint New Zealand-United States proposal for a Ross Sea region Marine Protected Area4. The MPA proposal provides a mechanism for ensuring spatial segregation between fishing effort and key foraging areas for toothfish predators. If the MPA proposal is adopted, important areas such as the Ross Sea shelf would be closed to toothfish fishing.
If adopted, the Ross Sea region Marine Protected Area would be the world’s largest MPA, encompassing 1.55 million square kilometres, of which 1.02 million square kilometres would be no-take. Integral to the MPA proposal is a comprehensive research and monitoring plan that seeks to encourage collaborative research by all CCAMLR Members in the Ross Sea. This would involve establishing long-term multi-disciplinary studies in collaboration with international partners to characterise the ecological relationships of toothfish, its predators and prey.
This update has been developed by the Science Team within the Fisheries Management Directorate of the Regulation and Assurance branch, Ministry for Primary Industries (MPI). It does not cover all issues but, as anticipated, includes more chapters than previous editions. As with the Reports from Fisheries Assessment Plenaries, it is expected to change and grow as new information becomes available, more issues are considered, and as feedback and ideas are received. This synopsis has a broad, national focus on each issue and the general approach has been to avoid too much detail at a local, fishery, or fishstock level. For instance, the benthic (seabed) effects of mobile bottom-fishing methods are dealt with at the level of all bottom trawl and dredge fisheries combined rather than at the level of a target fishery that, although it might be locally important, might contribute only a small proportion of the total impact. The details of benthic impacts by individual fisheries will be documented in the respective chapters in the May or November Report from the Fisheries Assessment Plenary, and linked there to the fine detail and analysis in Aquatic Environment and Biodiversity Reports (AEBRs), Fisheries Assessment Reports (FARs), and Final Research Reports (FRRs). Such sections have already been developed for several species in the Fishery Assessment Plenary Reports, and others will follow.
The first part of this document describes the legislative and broad policy context for aquatic environment and biodiversity research commissioned by MPI, and the science processes used to generate and review that research. The second, and main, part of the document contains chapters focused on various aquatic environment issues for fisheries management. Those chapters are divided into five broad themes: protected species; non- QMS (mostly fish) bycatch; benthic effects; ecosystem issues (including New Zealand’s oceanic setting); and marine biodiversity. A third part of the review includes a number of appendices for reference. This review is not yet comprehensive in its coverage of all issues or of all research within each issue, but attempts to summarise the best available information on the issues covered. Each chapter has been considered by the appropriate working group at least once.
• to evaluate EM and methods of implementing automatic collection of at-sea fisheries data;
• to compare data collected by EM reviewers and at-sea observers; and
• to evaluate the needs of an operational program for the use of EM within the inshore Set Net fishery.
This update has been developed by the Science Team within the Fisheries Management Directorate of the Resource Management and Programmes branch, Ministry for Primary Industries (MPI). It does not cover all issues but, as anticipated, includes more chapters than in 2011 and 2012. As with the Reports from Fisheries Assessment Plenaries, it is expected to change and grow as new information becomes available, more issues are considered, and as feedback and ideas are received. This synopsis has a broad, national focus on each issue and the general approach has been to avoid too much detail at a fishery or fishstock level. For instance, the benthic (seabed) effects of mobile bottom-fishing methods are dealt with at the level of all bottom trawl and dredge fisheries combined rather than at the level of a target fishery that might contribute only a small proportion of the total impact. The details of benthic impacts by individual fisheries will be documented in the respective chapters in the May or November Report from the Fisheries Assessment Plenary, and linked there to the fine detail and analysis in Aquatic Environment and Biodiversity Reports (AEBRs), Fisheries Assessment Reports (FARs), and Final Research Reports (FRRs). Such sections have already been developed for several species in the 2012 and 2013 Fishery Assessment Plenary Reports, and others will follow.
The first part of this document describes the legislative and broad policy context for aquatic environment and biodiversity research commissioned by MPI, and the science processes used to generate and review that research. The second, and main, part of the document contains chapters focused on various aquatic environment issues for fisheries management. Those chapters are divided into five broad themes: protected species; non-QMS fish bycatch; benthic effects; ecosystem issues (including New Zealand’s oceanic setting); and marine biodiversity. A third part of the review includes a number of appendices for reference. This review is not comprehensive in its coverage of all issues or of all research within each issue, but attempts to summarise the best available information on the issues covered. Each chapter has been considered by the appropriate working group at least once.
The panel’s scores combined for all identified threats suggested a broad range of plausible values for human-induced Maui’s dolphin mortalities over the next 5 years (a median of 5.27 dolphins per annum with 95% of the distribution of scores being between 0.97 and 8.40 dolphins per annum). The panel attributed 95.5% of these mortalities to commercial, recreational, customary or illegal fishing-related activities combined, and the remaining 4.5% to non-fishing-related threats.
Despite this uncertainty, the panel’s scores indicate high confidence that total human-induced mortality is higher than the population can sustain. Population projections based on the panel’s estimated total mortalities indicate a 95.7% likelihood that the population will decline if threats remain at current levels (i.e. as at the time of the workshop and prior to the introduction of interim measures). estimated total human-induced Maui’s dolphin mortalities equate to a level of impact that is many times higher than the estimated Potential Biological Removals (PBR; a median of 75.5 times PBR, with 95% of the distribution of estimates being between 12.4 and 150.7 times PBR).
The risk assessment method assessed the cumulative impact and associated population risk posed by all threats combined and also disaggregated the impacts of the respective threats, to identify those threats that pose the greatest risk to the dolphins. It also identified several threats that may have a low likelihood, but which, given the small population size of Maui’s dolphins, nonetheless may have detrimental consequences for the population.