Antarctic krill is a key species in the Southern Ocean and subject to the most extensive fishery ... more Antarctic krill is a key species in the Southern Ocean and subject to the most extensive fishery in the Antarctic. The Norwegian Institute of Marine Research has conducted acoustic-trawl monitoring of krill off the South Orkneys annually since 2011 in collaboration with the krill fishing industry. Average krill biomass within the 60000 km 2 survey area ranged from 1.4 to 7.8 million tonnes in the period 2011-2020, strongly supporting that this is among the regions in the Scotia Sea with consistently highest krill densities. There were no significant (p ≈ 0.18, nonparametric Mann-Kendall test) monotonic trends in estimated krill biomass over the 10 years. The highest krill densities were associated with the shelf edge and submarine canyons on the north side of the South Orkneys. Our comparison with the CCAMLR 9.3% reference exploitation rate suggests that management of the krill fishery in the South Orkneys region is precautionary. The monitoring is run on fishing vessels, so e.g. acoustic frequencies applied could not always be in compliance with the standard CCAMLR methodology. Estimated deviance in krill backscatter when comparing 38 kHz to the standard 120 kHz ranged from −1.1% to 12.8%. Our results show that industry-based surveys are cost-efficient approaches to high-quality monitoring of krill.
Commercial fisheries may impact marine ecosystems and affect populations of predators like seabir... more Commercial fisheries may impact marine ecosystems and affect populations of predators like seabirds. In the Southern Ocean, there is an extensive fishery for Antarctic krill Euphausia superba that is projected to increase further. Comparing distribution and prey selection of fishing operations versus predators is needed to predict fishery-related impacts on krill-dependent predators. In this context, it is important to consider not only predators breeding near the fishing grounds but also the ones breeding far away and that disperse during the non-breeding season where they may interact with fisheries. In this study, we first quantified the overlap between the distribution of the Antarctic krill fisheries and the distribution of a krill dependent seabird, the Antarctic petrel Thalassoica antarctica, during both the breeding and non-breeding season. We tracked birds from the world biggest Antarctic petrel colony (Svarthamaren, Dronning Maud Land), located >1000 km from the main fishing areas, during three consecutive seasons. The overall spatial overlap between krill fisheries and Antarctic petrels was limited but varied greatly among and within years, and was high in some periods during the non-breeding season. In a second step, we described the length frequency distribution of Antarctic krill consumed by Antarctic petrels, and compared this with results from fisheries, as well as from diet studies in other krill predators. Krill taken by Antarctic petrels did not differ in size from that taken by trawls or from krill taken by most Antarctic krill predators. Selectivity for specific Antarctic krill stages seems generally low in Antarctic predators. Overall, our results show that competition between Antarctic petrels and krill fisheries is currently likely negligible. However, if krill fisheries are to increase in the future, competition with the Antarctic petrel may occur, even with birds breeding thousands of kilometers away.
Experience gained through participation in international programmes like BIOMASS and the CCAMLR 2... more Experience gained through participation in international programmes like BIOMASS and the CCAMLR 2000 Survey has demonstrated that standardization of equipment and methods is one of the most crucial steps for any successful work during the field sampling period and later analytical work. The following net sampling and laboratory protocols are based on the protocols developed for the CCAMLR 2000 Survey. The aim is to facilitate a joint understanding of the field and laboratory work in order for participants that carry out the upcoming International Krill Synoptic Survey 2019 to collect comparable and highquality data. This will hopefully enable the establishment of a uniform and valuable database of comparable quality with data obtained through the CCAMLR 2000 Survey and other more recent surveys that have been conducted within the region of CCAMLR Area 48.
The previously presented document at the 2018 ASAM WG meeting (ASAM-18-07) described a design and... more The previously presented document at the 2018 ASAM WG meeting (ASAM-18-07) described a design and plans for a synoptic krill acoustic survey in CCAMLR area 48 in 2019. The survey involves the collaborative efforts of Norway, Association of Responsible Krill fishing companies (ARK: companies from Norway, Korea, China and Chile), the United Kingdom, Ukraine, Korea and China, all of whom have confirmed a commitment of survey ship time. With these commitments it is feasible to implement all transects occupied during the 2000 survey. This document is a draft survey manual, produced at the recommendation of the 2018 ASAM meeting, and describes acoustic procedures, acoustic reporting-analysis procedures and contingency plans.
ï‚· Users may download and print one copy of any publication from the public portal for the purpose... more ï‚· Users may download and print one copy of any publication from the public portal for the purpose of private study or research. ï‚· You may not further distribute the material or use it for any profit-making activity or commercial gain ï‚· You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
This paper explains the management of the Antarctic krill (Euphausia superba) fishery in the Atla... more This paper explains the management of the Antarctic krill (Euphausia superba) fishery in the Atlantic sector of the Southern Ocean, and current knowledge about the state of the regional krill stock. In this region, krill fishing is permitted in an area of approximately 3.5 million km 2 which is divided into four subareas (labelled Subareas 48.1 to 48.4) for management and reporting purposes. The effective regional catch limit (or 'trigger level'), established in 1991, is 0.62 million tonnes year-1 , equivalent to ~1% of the regional biomass estimated in 2000. Each subarea has also had its own catch limit, between 0.093 and 0.279 million tonnes year-1 , since 2009. There is some evidence for a decline in the abundance of krill in the 1980s, but no evidence of a further decline in recent decades. Local-scale monitoring programs have been established in three of the subareas to monitor krill biomass in survey grids covering between 10 000 and 125 000 km 2. Cautious extrapolation from these local monitoring programs provides conservative estimates of the regional biomass in recent years. This suggests that fishing at the trigger level would be equivalent to a long-term exploitation rate (annual catch divided by biomass) of <7%, which is below the 9.3% level considered appropriate to maintain the krill stock and support krill predators.
Fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) are commonly foun... more Fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) are commonly found in the Norwegian Sea during the summer months. Records from around 1995 to 2004 show that their distribution patterns were mainly associated with those of macro-zooplankton. More recent studies conducted from 2009 to 2012 demonstrate marked shifts, with fin whale distribution related to pelagic fish distribution, decreasing densities of humpbacks, and increased densities of toothed whales. During the same period, historically large abundances of pelagic planktivorous fish in the Norwegian Sea were reported. The goals of this study were to examine the summer distribution of fin and humpback whales from 2013 to 2018 and to assess the potential association between distribution and environmental impact factors. Results suggest a pronounced northerly shift in distribution for both species, a feeding hotspot for fin whales at the shelf area between Svalbard and Norway, and one near Bear Island for humpback whales. Fin whale distribution was associated with that of blue whiting (Micromesistius poutassou) and capelin (Mallotus villosus), whereas humpback whale distribution was associated with that of euphausiids (Meganyctiphanes norvegica, Thysanoessa longicaudata, and Thysanoessa inermis), capelin, and herring (Clupea harengus). However, a significant negative spatial correlation was found between whale occurrence and the widely expanding population of northeast Atlantic mackerel (Scomber scombrus). The results of this study suggest that the prey composition of fin and humpback whales in recent years contain a large proportion of fish. The apparent northerly shift in the distribution of these whale species is largely determined by the availability of prey, but it likely is also impacted by direct or indirect interspecific interactions, especially with killer whales (Orcinus orca). Such large-scale pronounced changes in distribution seem to confirm a high degree of plasticity in fin and humpback whale feeding in the Norwegian Sea.
Antarctic krill (Euphausia superba) and salps are major macroplankton contributors to Southern Oc... more Antarctic krill (Euphausia superba) and salps are major macroplankton contributors to Southern Ocean food webs and krill are also fished commercially. Managing this fishery sustainably, against a backdrop of rapid regional climate change, requires information on distribution and time trends. Many data on the abundance of both taxa have been obtained from net sampling surveys since 1926, but much of this is stored in national archives, sometimes only in notebooks. In order to make these important data accessible we have collated available abundance data (numerical density, no. m −2) of postlarval E. superba and salp individual (multiple species,
WG-EMM-15/28 Updating the Antarctic krill biomass estimates for CCAMLR Subareas 48.1 to 48.4 usin... more WG-EMM-15/28 Updating the Antarctic krill biomass estimates for CCAMLR Subareas 48.1 to 48.4 using available data
Following the cessation of whaling, South Atlantic populations of humpbackMegaptera novaeangliaea... more Following the cessation of whaling, South Atlantic populations of humpbackMegaptera novaeangliaeand some other baleen whale species are recovering, but there has been limited monitoring of their recovery in the Scotia Arc, a former whaling epicentre and a hotspot for Antarctic krillEuphausia superba. To inform the management of krill fisheries, up-to-date assessment of whale biomass and prey consumption is essential. Using a model-based approach, we provide the first estimates of whale abundance and krill consumption for South Georgia and the South Sandwich Islands and total abundance of humpback whales across their southwestern Atlantic feeding grounds, using data collected in 2019. Humpback whale abundance was estimated at 24543 (coefficient of variation, CV = 0.26; 95% CI = 14863-40528), similar to that measured in Brazil on the main wintering ground for this population. The abundance of baleen whales in South Georgia and the South Sandwich Islands, including those not identified...
The traditional perception of prey species preference of killer whales Orcinus orca L. in the Nor... more The traditional perception of prey species preference of killer whales Orcinus orca L. in the Northeast Atlantic has, to a large extent, been linked to herring Clupea harengus L. Few studies have investigated the feeding ecology of killer whales from the offshore parts of this ecosystem. We conducted 2 summer-season ecosystem-based surveys in the Norwegian Sea, when it is most crucial for these animals to build up their energy reserves, using observational, acoustic, oceanographic, plankton net, and pelagic trawl haul data to quantify any spatial overlap between killer whales and the 3 most common and abundant pelagic fish species: herring, mackerel Scomber scombrus L., and blue whiting Micromesistius poutassou R. No spatial relationships were found between killer whales and herring or blue whiting. However, there was a significant relationship and spatial overlap between killer whales and mackerel. Feeding on this epipelagic schooling fish species during summer may incur lower migration costs and higher energetic gain than feeding on alternative prey. Killer whale group size was also correlated to the size of mackerel trawl catches, indicating active group size adjustment to available prey concentrations.
The primary objective for this project is to develop knowledge on the marine environment essentia... more The primary objective for this project is to develop knowledge on the marine environment essential for the implementation of a FeedBack Management (FBM) system. In terms of FBM, Marine Protected Area (MPA) development in CCAMLR Planning Domain 1 encompasses the major krill fishing grounds. Thus, data supporting FBM as an integral part of the broader management strategies of the krill fisheries within Domain 1 are critical if the fishery is to be managed by an empirical understanding of krill density, distribution, availability and predator needs. A future developed FBM system, as presented in SC-CAMLR XXXVI/BG20 requires acoustic data to be collected, processed and reported continuously during the fishing season as a measure of the available prey field. This information can be integrated with finer-scale knowledge of krill predator feeding strategies and updated through specific scientific studies at regular (multiyear) intervals. The FBM process studies will take place during the Austral summer 2018-2019.
Antarctic krill is a key species in the Southern Ocean and subject to the most extensive fishery ... more Antarctic krill is a key species in the Southern Ocean and subject to the most extensive fishery in the Antarctic. The Norwegian Institute of Marine Research has conducted acoustic-trawl monitoring of krill off the South Orkneys annually since 2011 in collaboration with the krill fishing industry. Average krill biomass within the 60000 km 2 survey area ranged from 1.4 to 7.8 million tonnes in the period 2011-2020, strongly supporting that this is among the regions in the Scotia Sea with consistently highest krill densities. There were no significant (p ≈ 0.18, nonparametric Mann-Kendall test) monotonic trends in estimated krill biomass over the 10 years. The highest krill densities were associated with the shelf edge and submarine canyons on the north side of the South Orkneys. Our comparison with the CCAMLR 9.3% reference exploitation rate suggests that management of the krill fishery in the South Orkneys region is precautionary. The monitoring is run on fishing vessels, so e.g. acoustic frequencies applied could not always be in compliance with the standard CCAMLR methodology. Estimated deviance in krill backscatter when comparing 38 kHz to the standard 120 kHz ranged from −1.1% to 12.8%. Our results show that industry-based surveys are cost-efficient approaches to high-quality monitoring of krill.
Commercial fisheries may impact marine ecosystems and affect populations of predators like seabir... more Commercial fisheries may impact marine ecosystems and affect populations of predators like seabirds. In the Southern Ocean, there is an extensive fishery for Antarctic krill Euphausia superba that is projected to increase further. Comparing distribution and prey selection of fishing operations versus predators is needed to predict fishery-related impacts on krill-dependent predators. In this context, it is important to consider not only predators breeding near the fishing grounds but also the ones breeding far away and that disperse during the non-breeding season where they may interact with fisheries. In this study, we first quantified the overlap between the distribution of the Antarctic krill fisheries and the distribution of a krill dependent seabird, the Antarctic petrel Thalassoica antarctica, during both the breeding and non-breeding season. We tracked birds from the world biggest Antarctic petrel colony (Svarthamaren, Dronning Maud Land), located >1000 km from the main fishing areas, during three consecutive seasons. The overall spatial overlap between krill fisheries and Antarctic petrels was limited but varied greatly among and within years, and was high in some periods during the non-breeding season. In a second step, we described the length frequency distribution of Antarctic krill consumed by Antarctic petrels, and compared this with results from fisheries, as well as from diet studies in other krill predators. Krill taken by Antarctic petrels did not differ in size from that taken by trawls or from krill taken by most Antarctic krill predators. Selectivity for specific Antarctic krill stages seems generally low in Antarctic predators. Overall, our results show that competition between Antarctic petrels and krill fisheries is currently likely negligible. However, if krill fisheries are to increase in the future, competition with the Antarctic petrel may occur, even with birds breeding thousands of kilometers away.
Experience gained through participation in international programmes like BIOMASS and the CCAMLR 2... more Experience gained through participation in international programmes like BIOMASS and the CCAMLR 2000 Survey has demonstrated that standardization of equipment and methods is one of the most crucial steps for any successful work during the field sampling period and later analytical work. The following net sampling and laboratory protocols are based on the protocols developed for the CCAMLR 2000 Survey. The aim is to facilitate a joint understanding of the field and laboratory work in order for participants that carry out the upcoming International Krill Synoptic Survey 2019 to collect comparable and highquality data. This will hopefully enable the establishment of a uniform and valuable database of comparable quality with data obtained through the CCAMLR 2000 Survey and other more recent surveys that have been conducted within the region of CCAMLR Area 48.
The previously presented document at the 2018 ASAM WG meeting (ASAM-18-07) described a design and... more The previously presented document at the 2018 ASAM WG meeting (ASAM-18-07) described a design and plans for a synoptic krill acoustic survey in CCAMLR area 48 in 2019. The survey involves the collaborative efforts of Norway, Association of Responsible Krill fishing companies (ARK: companies from Norway, Korea, China and Chile), the United Kingdom, Ukraine, Korea and China, all of whom have confirmed a commitment of survey ship time. With these commitments it is feasible to implement all transects occupied during the 2000 survey. This document is a draft survey manual, produced at the recommendation of the 2018 ASAM meeting, and describes acoustic procedures, acoustic reporting-analysis procedures and contingency plans.
ï‚· Users may download and print one copy of any publication from the public portal for the purpose... more ï‚· Users may download and print one copy of any publication from the public portal for the purpose of private study or research. ï‚· You may not further distribute the material or use it for any profit-making activity or commercial gain ï‚· You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
This paper explains the management of the Antarctic krill (Euphausia superba) fishery in the Atla... more This paper explains the management of the Antarctic krill (Euphausia superba) fishery in the Atlantic sector of the Southern Ocean, and current knowledge about the state of the regional krill stock. In this region, krill fishing is permitted in an area of approximately 3.5 million km 2 which is divided into four subareas (labelled Subareas 48.1 to 48.4) for management and reporting purposes. The effective regional catch limit (or 'trigger level'), established in 1991, is 0.62 million tonnes year-1 , equivalent to ~1% of the regional biomass estimated in 2000. Each subarea has also had its own catch limit, between 0.093 and 0.279 million tonnes year-1 , since 2009. There is some evidence for a decline in the abundance of krill in the 1980s, but no evidence of a further decline in recent decades. Local-scale monitoring programs have been established in three of the subareas to monitor krill biomass in survey grids covering between 10 000 and 125 000 km 2. Cautious extrapolation from these local monitoring programs provides conservative estimates of the regional biomass in recent years. This suggests that fishing at the trigger level would be equivalent to a long-term exploitation rate (annual catch divided by biomass) of <7%, which is below the 9.3% level considered appropriate to maintain the krill stock and support krill predators.
Fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) are commonly foun... more Fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) are commonly found in the Norwegian Sea during the summer months. Records from around 1995 to 2004 show that their distribution patterns were mainly associated with those of macro-zooplankton. More recent studies conducted from 2009 to 2012 demonstrate marked shifts, with fin whale distribution related to pelagic fish distribution, decreasing densities of humpbacks, and increased densities of toothed whales. During the same period, historically large abundances of pelagic planktivorous fish in the Norwegian Sea were reported. The goals of this study were to examine the summer distribution of fin and humpback whales from 2013 to 2018 and to assess the potential association between distribution and environmental impact factors. Results suggest a pronounced northerly shift in distribution for both species, a feeding hotspot for fin whales at the shelf area between Svalbard and Norway, and one near Bear Island for humpback whales. Fin whale distribution was associated with that of blue whiting (Micromesistius poutassou) and capelin (Mallotus villosus), whereas humpback whale distribution was associated with that of euphausiids (Meganyctiphanes norvegica, Thysanoessa longicaudata, and Thysanoessa inermis), capelin, and herring (Clupea harengus). However, a significant negative spatial correlation was found between whale occurrence and the widely expanding population of northeast Atlantic mackerel (Scomber scombrus). The results of this study suggest that the prey composition of fin and humpback whales in recent years contain a large proportion of fish. The apparent northerly shift in the distribution of these whale species is largely determined by the availability of prey, but it likely is also impacted by direct or indirect interspecific interactions, especially with killer whales (Orcinus orca). Such large-scale pronounced changes in distribution seem to confirm a high degree of plasticity in fin and humpback whale feeding in the Norwegian Sea.
Antarctic krill (Euphausia superba) and salps are major macroplankton contributors to Southern Oc... more Antarctic krill (Euphausia superba) and salps are major macroplankton contributors to Southern Ocean food webs and krill are also fished commercially. Managing this fishery sustainably, against a backdrop of rapid regional climate change, requires information on distribution and time trends. Many data on the abundance of both taxa have been obtained from net sampling surveys since 1926, but much of this is stored in national archives, sometimes only in notebooks. In order to make these important data accessible we have collated available abundance data (numerical density, no. m −2) of postlarval E. superba and salp individual (multiple species,
WG-EMM-15/28 Updating the Antarctic krill biomass estimates for CCAMLR Subareas 48.1 to 48.4 usin... more WG-EMM-15/28 Updating the Antarctic krill biomass estimates for CCAMLR Subareas 48.1 to 48.4 using available data
Following the cessation of whaling, South Atlantic populations of humpbackMegaptera novaeangliaea... more Following the cessation of whaling, South Atlantic populations of humpbackMegaptera novaeangliaeand some other baleen whale species are recovering, but there has been limited monitoring of their recovery in the Scotia Arc, a former whaling epicentre and a hotspot for Antarctic krillEuphausia superba. To inform the management of krill fisheries, up-to-date assessment of whale biomass and prey consumption is essential. Using a model-based approach, we provide the first estimates of whale abundance and krill consumption for South Georgia and the South Sandwich Islands and total abundance of humpback whales across their southwestern Atlantic feeding grounds, using data collected in 2019. Humpback whale abundance was estimated at 24543 (coefficient of variation, CV = 0.26; 95% CI = 14863-40528), similar to that measured in Brazil on the main wintering ground for this population. The abundance of baleen whales in South Georgia and the South Sandwich Islands, including those not identified...
The traditional perception of prey species preference of killer whales Orcinus orca L. in the Nor... more The traditional perception of prey species preference of killer whales Orcinus orca L. in the Northeast Atlantic has, to a large extent, been linked to herring Clupea harengus L. Few studies have investigated the feeding ecology of killer whales from the offshore parts of this ecosystem. We conducted 2 summer-season ecosystem-based surveys in the Norwegian Sea, when it is most crucial for these animals to build up their energy reserves, using observational, acoustic, oceanographic, plankton net, and pelagic trawl haul data to quantify any spatial overlap between killer whales and the 3 most common and abundant pelagic fish species: herring, mackerel Scomber scombrus L., and blue whiting Micromesistius poutassou R. No spatial relationships were found between killer whales and herring or blue whiting. However, there was a significant relationship and spatial overlap between killer whales and mackerel. Feeding on this epipelagic schooling fish species during summer may incur lower migration costs and higher energetic gain than feeding on alternative prey. Killer whale group size was also correlated to the size of mackerel trawl catches, indicating active group size adjustment to available prey concentrations.
The primary objective for this project is to develop knowledge on the marine environment essentia... more The primary objective for this project is to develop knowledge on the marine environment essential for the implementation of a FeedBack Management (FBM) system. In terms of FBM, Marine Protected Area (MPA) development in CCAMLR Planning Domain 1 encompasses the major krill fishing grounds. Thus, data supporting FBM as an integral part of the broader management strategies of the krill fisheries within Domain 1 are critical if the fishery is to be managed by an empirical understanding of krill density, distribution, availability and predator needs. A future developed FBM system, as presented in SC-CAMLR XXXVI/BG20 requires acoustic data to be collected, processed and reported continuously during the fishing season as a measure of the available prey field. This information can be integrated with finer-scale knowledge of krill predator feeding strategies and updated through specific scientific studies at regular (multiyear) intervals. The FBM process studies will take place during the Austral summer 2018-2019.
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