The purpose of this Theme Section (TS) is to discuss various aspects of quality, and quality assu... more The purpose of this Theme Section (TS) is to discuss various aspects of quality, and quality assurance, in science publishing. While we will each have our own views about exactly what this means, the editorial policy statement of the Council of Science Editors uses the following adjectives in reference to the quality of a scientific journal’s content: accurate, valid, reliable, credible, authoritative, relevant to the journal’s scope and mission, readable, and comprehensible. A standard dictionary definition of quality control is: ‘...a method of establishing and maintaining a high level of quality in a product or process through careful organizing, constant checking and painstaking corrections.’ In this context, most of us would probably agree that the publisher, the editorial board, the reviewers and (not least) the authors are all involved in creating, defining, measuring and maintaining quality. Thus, we asked a cross-section of people with experience of one or more aspects of s...
while we were interested in decadal-scale variability and the existence of relatively stable stat... more while we were interested in decadal-scale variability and the existence of relatively stable states (i.e., regimes) with rapid transitions (i.e., shifts) between them. Our project had three components: first, data rescue of historical datasets on tuna diet in the Pacific and comparison with data collected in recent years; second, objective characterization of oceanographic variability and derivation of oceanographic indicators; and third, development of statistical models relating oceanographic variability to tuna recruitment. The first two components seek to improve our ecological understanding while the third seeks to apply that knowledge to improving stock assessments and projections.
while we were interested in decadal-scale variability and the existence of relatively stable stat... more while we were interested in decadal-scale variability and the existence of relatively stable states (i.e., regimes) with rapid transitions (i.e., shifts) between them. Our project had three components: first, data rescue of historical datasets on tuna diet in the Pacific and comparison with data collected in recent years; second, objective characterization of oceanographic variability and derivation of oceanographic indicators; and third, development of statistical models relating oceanographic variability to tuna recruitment. The first two components seek to improve our ecological understanding while the third seeks to apply that knowledge to improving stock assessments and projections. Tuna Diet Analysis Diet data was obtained from a 1975 study by R. Grandperrin in New Caledonia and from the ECOTAP (Etude du Comportement Regime Shifts (continued from page 1) Figure 2. Time series for Southern Oscillation Index (SOI) and Pacific Decadal Oscillation (PDO) ocean-basin-scale indicators of atmospheric pressure and sea-surface temperature, respectively. Dates of statistically significant regime shifts are shown.
1) Ecosystem indicators are a way of reducing ecosystem complexity into a form that is most infor... more 1) Ecosystem indicators are a way of reducing ecosystem complexity into a form that is most informative and useful to management. As a means of turning data into information, indicators are ultimately a communication tool facilitating science-based governance, i.e. the sustainable use of WCPO tuna resources and the conservation of associated species. 2) One framework suggested for the development of quantitative ecosystem indicators is PSR: Pressure-State-Response. This approach attempts to identify key forcing variables (e.g. oceanographic indices, fishing mortality), measures of system state, for the ecosystem and for individual components (e.g. stock status for target species) and indicators of system response to the pressures identified and to management action. 3) Appropriate methodologies for the derivation of indicators include univariate, bivariate and multivariate data analysis. These allow the investigation of single properties, the comparison of two or more properties (usually to investigate cause and effect), and the derivation of single indicators describing multiple series collectively representing the ecosystem as a whole. 4) In developing ecosystem indicators we must bear in mind the divisions of responsibility between ecosystem science and resource management. Scientists can suggest what analyses are feasible and sensible to do while resource managers must determine what scientific information they want, alongside other information concerning stakeholder priorities, how to reconcile different interests and decide on appropriate action. This is particularly so under an ecosystem approach to fisheries management, which requires value judgements based on economic, ecological and social trade-offs. 5) In conclusion, indicators will be important to identify ecosystem fluctuations affecting fisheries performance (e.g. potential changes in yields) and ecological impacts of fishing. The development of ecosystem indicators should allow all stakeholders (managers, investors, fishers, conservationists and other communities) to identify and better understand natural and fishery induced changes in marine ecosystems.
The Australian Centre for International Agricultural Research (ACIAR) was established in June 198... more The Australian Centre for International Agricultural Research (ACIAR) was established in June 1982 by an Act of the Australian Parliament. Its mandate is to help identify agricultural problems in developing countries and to commission collaborative research between Australian and developing country researchers in fields where Australia has a special research competence. Where trade names are used this constitutes neither endorsement of nor discrimination against any product by the Centre.
New Zealand Journal of Marine and Freshwater Research, 2003
Exploratory data analysis of a highresolution (hook-by-hook), 6-year time series (1993-98) of obs... more Exploratory data analysis of a highresolution (hook-by-hook), 6-year time series (1993-98) of observed longline catch data for tunas was used to investigate fine-scale spatial patterns along individual sets that may be indicative of social behaviour (i.e., schooling) and/or the response of individual fish to favourable extrinsic conditions (i.e., aggregation). Methods of spatial data analysis (i.e., nearest neighbour analysis) that have previously been applied in various other sciences (e.g., forestry and astronomy) were used. Results indicate strong clustering of individual tunas at characteristic scales within the set. Mean Nearest Neighbour Distances (NNDs) were between 100 and 200 m, compared with NNDs of 200-700 m predicted by a heterogeneous Poisson process on the same spatial domain. The results suggest that these adult tunas were either schooling or aggregating at the time of capture; this may therefore be related either to social behaviour or to sub-mesoscale oceanographic features. An aggregation index was derived from the NNDs, giving a classification method that may be used for similar data and the development of empirical models attempting to relate patterns in fish catch distributions to environmental variables. The success of such models will ultimately depend on elucidating the ecological processes reflected in oceanographic features at biologically meaningful spatial scales.
ABSTRACT Developments in fisheries governance in recent decades—notably the 1982 United Nations C... more ABSTRACT Developments in fisheries governance in recent decades—notably the 1982 United Nations Convention on the Law of the Sea and its implementing agreements—have established a framework of principles, standards, institutions and regulations that is broader and more complex than traditional fisheries management, which has generally focused on individual target species. As this framework has evolved, a number of seafood eco-labelling schemes have also developed. These schemes aim to identify well-managed fisheries and give competitive advantage to their products, thus translating the environmental awareness of consumers into direct support for sustainable fishing practices. This paper evaluates a number of these schemes in the context of international fisheries governance principles and considers the conservation benefits that may result from sustainability certification of Pacific tuna fisheries. The paper briefly summarises developments in eco-labeling of Pacific tuna fisheries in relation to the evolution of fisheries management, where focus has shifted from the maximum sustainable yield of individual tuna species to ecosystem-based approaches that directly consider the broader environmental impacts of fishing. The paper discusses two different ‘Dolphin Safe’ eco-labels, the third-party scheme of the Earth Island Institute and the intergovernmental scheme of the Agreement on the International Dolphin Conservation Program, and two broader eco-labels offering sustainability certification of fisheries, ‘Friend of the Sea’ and the ‘Marine Stewardship Council’. The role played by seafood-industry associations with sustainability claims, such as the International Seafood Sustainability Foundation, is also considered.
ABSTRACT The risk of seabird–fishery interactions in the Western and Central Pacific Ocean (WCPO)... more ABSTRACT The risk of seabird–fishery interactions in the Western and Central Pacific Ocean (WCPO) was examined by analysing the overlap of seabird distributions with tuna and swordfish pelagic longline fisheries managed by the Western and Central Pacific Fisheries Commission (WCPFC) and its constituent members. The study used spatially-explicit Productivity–Susceptibility Analysis (PSA). Key data inputs were species productivity, fishing effort, likelihood of capture and species density by region. The outputs tailored results to the needs of fisheries- and wildlife-managers, indicating areas of greatest risk of species interactions, species of greatest concern for population impacts, and the flags or fisheries most likely to contribute to the risk. Large albatross species were found to be most likely to suffer population effects when exposed to longline fishing activity, followed by the larger petrels from the genuses Procellaria, Macronectes and Pterodroma. A mixture of coastal states with nesting seabird populations in their Exclusive Economic Zones (New Zealand, Australia and United States of America), distant water fishing nations (Japan, Taiwan) and flags of convenience (Vanuatu) contributed 90% of the risk to seabird populations. Recommendations include enhancing the level of fisheries observer monitoring in areas indicated as high to medium risk for seabird interactions, and consideration of spatial management tools, such as more intensive or more stringent seabird bycatch mitigation requirements in high- to medium-risk areas. The methods used, and similar studies conducted in the Atlantic Ocean could lead to improved targeting of monitoring resources, and greater specificity in the needs for seabird-mitigation measures. This will assist in reducing seabird mortality in longline fishing operations and with more effective use of resources for fishery managers in both domestic fisheries and RFMOs.
The valuable sea cucumber Holothuria scabra, known as 'sandfish', has potential for restocking. H... more The valuable sea cucumber Holothuria scabra, known as 'sandfish', has potential for restocking. However, there is little information available to determine the size of the no-take zones (NTZs) needed to protect the released animals so that they can form nucleus breeding populations. To do this, we measured short-term movement paths of released juvenile (1-105 g) and wild adult (130-690 g) sandfish in a seagrass bed in New Caledonia. We then developed an individual-based model (IBM) to predict long-term dispersal of sandfish released as juveniles (1-16 g) at 1 individual m −2 within a 1-ha area, drawing on distributions of speed and directionality and the relationship between speed and animal weight from field data. Movement was non-random at the sampling scale used, since animals tended to turn <90 • at each 2-h time step. We examined high-and low-growth scenarios by applying 50% and 25% of the modelled growth rates of sandfish held in earthen ponds (where they are known to grow faster). The dispersal of released sandfish was predicted to be limited in the first 2 years, then markedly faster thereafter. After 10 years, 6-12% of surviving animals were predicted to remain in the original 1-ha release site. To protect surviving sandfish as nucleus breeding populations for 10 years, and accepting 10% spillover, square NTZs would need to be 19-40 ha. The findings are useful for the management of restocking and pre-defining the size of sites for recapture surveys. Our model allows user-specified values for future releases and should be applicable for other sedentary marine invertebrates where basic data on movement and growth are available.
Different stock-recruitment models were fitted to North Atlantic albacore (Thunnus alalunga) recr... more Different stock-recruitment models were fitted to North Atlantic albacore (Thunnus alalunga) recruitment and spawning stock biomass data. A classical density dependence hypothesis, a recent environmental-dependence hypothesis and a combination of both were considered. For the latter case, four stockenvironment-recruitment models were used: Ricker, Beverton-Holt, Deriso's General Model (modified to take into account environmental effects) and conditioned Neural Networks. Cross-validation analysis showed that the modified Deriso model had the best predictive capability. It detected an inverse effect of the North Atlantic Oscillation (NAO) on recruitment, a Ricker-type behaviour with density dependent overcompensation when environmental conditions are unfavourable and a Beverton-Holt-type behaviour towards an asymptotic recruitment carrying capacity with favourable environmental conditions. The Neural Network model also detected that under favourable environmental conditions high spawning stock biomass does not necessarily have a depensatory effect on recruitment. Moreover, they suggest that under extremely favourable environmental conditions, albacore recruitment could increase well above the asymptotic carrying capacity predicted by Beverton-Holt-type models. However, the general decrease in spawning stock biomass in recent years and increasing NAO trends suggest that there is low probability of exceptionally large recruitment in the future and instead there is a danger of recruitment overfishing.
Functional group name Functional group description Justification Swordfish Large Xiphias gladius ... more Functional group name Functional group description Justification Swordfish Large Xiphias gladius Other billfish Large Istiophorus platypterus, Makaira indica, Makaira mazara, Tetrapturus audax, Tetrapturus angustirostris Blue shark Large Prionace glauca Other sharks Large Alopiidae, Carcharhinidae, Lamnidae, Sphyrnidae Bigeye tuna Thunnus obesus larger than class size/age/weight at 50% of maturity 124cm/3.85y-46.2months/43kg* Yellowfin tuna Thunnus albacares larger than class size/age/weight at 50% of maturity 120cm/2.25y-27months/33kg* Skipjack tuna Katsuwonus pelamis larger than class size/age/weight at 100% of maturity 43cm/0.75y-9months/1.6kg* Piscivorous fish Alepisauridae, Bramidae, Carangidae, Coryphaenidae, Gempylidae, wahoo Acanthocybium solandri, opah Lampris guttatus, small Scombridae Bycatch species of interest for ecosystem management but species by species information not available. Small billfish Small billfish, same species as large groups swordfish and other billfish Small sharks Small sharks, same species as large groups blue shark and other sharks Small bigeye tuna Thunnus obesus smaller than class size/age/weight at 50% of maturity 124cm/3.85y-46.2months/43kg and larger than 20cm/3 months/0.18kg* Small yellowfin tuna Thunnus albacares smaller than class size/age/weight at 50% of maturity 120cm/2.25y-27months/33kg and larger than 24cm/3 months/0.33kg* Small skipjack tuna Katsuwonus pelamis smaller than class size/age/weight at 100% of maturity 43cm/0.75y-9months/1.6kg and larger than 24cm/3 months/0.25kg* Baby SKJ Katsuwonus pelamis from hatching to recruitement = 0 to 3 months, smaller than 24cm/0.25kg* Additional group required to decrease the importance of cannibalism and balance the model Epipelagic forage
Electronic tagging and tracking in marine fisheries. …, 2001
... Ab-stract available: http://www.soest.hawaii.edu/PFRP/brill_afs.pdf Brill, RW, Block, BA, Bog... more ... Ab-stract available: http://www.soest.hawaii.edu/PFRP/brill_afs.pdf Brill, RW, Block, BA, Boggs, CH, Bigelow, KA, Freund, EV and Marcinek, DJ (1999) Horizontal ... Fielder, P., and Bernard, H. (1987) Tuna aggregation and feeding near fronts observed in satellite imagery. Cont. ...
Seamounts are habitats of considerable interest in terms of conservation and biodiversity, and in... more Seamounts are habitats of considerable interest in terms of conservation and biodiversity, and in terms of fisheries for bentho-pelagic and pelagic species. Twenty previously compiled datasets including seamount/underwater feature lists, bathymetric maps and emerged feature ...
The purpose of this Theme Section (TS) is to discuss various aspects of quality, and quality assu... more The purpose of this Theme Section (TS) is to discuss various aspects of quality, and quality assurance, in science publishing. While we will each have our own views about exactly what this means, the editorial policy statement of the Council of Science Editors uses the following adjectives in reference to the quality of a scientific journal’s content: accurate, valid, reliable, credible, authoritative, relevant to the journal’s scope and mission, readable, and comprehensible. A standard dictionary definition of quality control is: ‘...a method of establishing and maintaining a high level of quality in a product or process through careful organizing, constant checking and painstaking corrections.’ In this context, most of us would probably agree that the publisher, the editorial board, the reviewers and (not least) the authors are all involved in creating, defining, measuring and maintaining quality. Thus, we asked a cross-section of people with experience of one or more aspects of s...
while we were interested in decadal-scale variability and the existence of relatively stable stat... more while we were interested in decadal-scale variability and the existence of relatively stable states (i.e., regimes) with rapid transitions (i.e., shifts) between them. Our project had three components: first, data rescue of historical datasets on tuna diet in the Pacific and comparison with data collected in recent years; second, objective characterization of oceanographic variability and derivation of oceanographic indicators; and third, development of statistical models relating oceanographic variability to tuna recruitment. The first two components seek to improve our ecological understanding while the third seeks to apply that knowledge to improving stock assessments and projections.
while we were interested in decadal-scale variability and the existence of relatively stable stat... more while we were interested in decadal-scale variability and the existence of relatively stable states (i.e., regimes) with rapid transitions (i.e., shifts) between them. Our project had three components: first, data rescue of historical datasets on tuna diet in the Pacific and comparison with data collected in recent years; second, objective characterization of oceanographic variability and derivation of oceanographic indicators; and third, development of statistical models relating oceanographic variability to tuna recruitment. The first two components seek to improve our ecological understanding while the third seeks to apply that knowledge to improving stock assessments and projections. Tuna Diet Analysis Diet data was obtained from a 1975 study by R. Grandperrin in New Caledonia and from the ECOTAP (Etude du Comportement Regime Shifts (continued from page 1) Figure 2. Time series for Southern Oscillation Index (SOI) and Pacific Decadal Oscillation (PDO) ocean-basin-scale indicators of atmospheric pressure and sea-surface temperature, respectively. Dates of statistically significant regime shifts are shown.
1) Ecosystem indicators are a way of reducing ecosystem complexity into a form that is most infor... more 1) Ecosystem indicators are a way of reducing ecosystem complexity into a form that is most informative and useful to management. As a means of turning data into information, indicators are ultimately a communication tool facilitating science-based governance, i.e. the sustainable use of WCPO tuna resources and the conservation of associated species. 2) One framework suggested for the development of quantitative ecosystem indicators is PSR: Pressure-State-Response. This approach attempts to identify key forcing variables (e.g. oceanographic indices, fishing mortality), measures of system state, for the ecosystem and for individual components (e.g. stock status for target species) and indicators of system response to the pressures identified and to management action. 3) Appropriate methodologies for the derivation of indicators include univariate, bivariate and multivariate data analysis. These allow the investigation of single properties, the comparison of two or more properties (usually to investigate cause and effect), and the derivation of single indicators describing multiple series collectively representing the ecosystem as a whole. 4) In developing ecosystem indicators we must bear in mind the divisions of responsibility between ecosystem science and resource management. Scientists can suggest what analyses are feasible and sensible to do while resource managers must determine what scientific information they want, alongside other information concerning stakeholder priorities, how to reconcile different interests and decide on appropriate action. This is particularly so under an ecosystem approach to fisheries management, which requires value judgements based on economic, ecological and social trade-offs. 5) In conclusion, indicators will be important to identify ecosystem fluctuations affecting fisheries performance (e.g. potential changes in yields) and ecological impacts of fishing. The development of ecosystem indicators should allow all stakeholders (managers, investors, fishers, conservationists and other communities) to identify and better understand natural and fishery induced changes in marine ecosystems.
The Australian Centre for International Agricultural Research (ACIAR) was established in June 198... more The Australian Centre for International Agricultural Research (ACIAR) was established in June 1982 by an Act of the Australian Parliament. Its mandate is to help identify agricultural problems in developing countries and to commission collaborative research between Australian and developing country researchers in fields where Australia has a special research competence. Where trade names are used this constitutes neither endorsement of nor discrimination against any product by the Centre.
New Zealand Journal of Marine and Freshwater Research, 2003
Exploratory data analysis of a highresolution (hook-by-hook), 6-year time series (1993-98) of obs... more Exploratory data analysis of a highresolution (hook-by-hook), 6-year time series (1993-98) of observed longline catch data for tunas was used to investigate fine-scale spatial patterns along individual sets that may be indicative of social behaviour (i.e., schooling) and/or the response of individual fish to favourable extrinsic conditions (i.e., aggregation). Methods of spatial data analysis (i.e., nearest neighbour analysis) that have previously been applied in various other sciences (e.g., forestry and astronomy) were used. Results indicate strong clustering of individual tunas at characteristic scales within the set. Mean Nearest Neighbour Distances (NNDs) were between 100 and 200 m, compared with NNDs of 200-700 m predicted by a heterogeneous Poisson process on the same spatial domain. The results suggest that these adult tunas were either schooling or aggregating at the time of capture; this may therefore be related either to social behaviour or to sub-mesoscale oceanographic features. An aggregation index was derived from the NNDs, giving a classification method that may be used for similar data and the development of empirical models attempting to relate patterns in fish catch distributions to environmental variables. The success of such models will ultimately depend on elucidating the ecological processes reflected in oceanographic features at biologically meaningful spatial scales.
ABSTRACT Developments in fisheries governance in recent decades—notably the 1982 United Nations C... more ABSTRACT Developments in fisheries governance in recent decades—notably the 1982 United Nations Convention on the Law of the Sea and its implementing agreements—have established a framework of principles, standards, institutions and regulations that is broader and more complex than traditional fisheries management, which has generally focused on individual target species. As this framework has evolved, a number of seafood eco-labelling schemes have also developed. These schemes aim to identify well-managed fisheries and give competitive advantage to their products, thus translating the environmental awareness of consumers into direct support for sustainable fishing practices. This paper evaluates a number of these schemes in the context of international fisheries governance principles and considers the conservation benefits that may result from sustainability certification of Pacific tuna fisheries. The paper briefly summarises developments in eco-labeling of Pacific tuna fisheries in relation to the evolution of fisheries management, where focus has shifted from the maximum sustainable yield of individual tuna species to ecosystem-based approaches that directly consider the broader environmental impacts of fishing. The paper discusses two different ‘Dolphin Safe’ eco-labels, the third-party scheme of the Earth Island Institute and the intergovernmental scheme of the Agreement on the International Dolphin Conservation Program, and two broader eco-labels offering sustainability certification of fisheries, ‘Friend of the Sea’ and the ‘Marine Stewardship Council’. The role played by seafood-industry associations with sustainability claims, such as the International Seafood Sustainability Foundation, is also considered.
ABSTRACT The risk of seabird–fishery interactions in the Western and Central Pacific Ocean (WCPO)... more ABSTRACT The risk of seabird–fishery interactions in the Western and Central Pacific Ocean (WCPO) was examined by analysing the overlap of seabird distributions with tuna and swordfish pelagic longline fisheries managed by the Western and Central Pacific Fisheries Commission (WCPFC) and its constituent members. The study used spatially-explicit Productivity–Susceptibility Analysis (PSA). Key data inputs were species productivity, fishing effort, likelihood of capture and species density by region. The outputs tailored results to the needs of fisheries- and wildlife-managers, indicating areas of greatest risk of species interactions, species of greatest concern for population impacts, and the flags or fisheries most likely to contribute to the risk. Large albatross species were found to be most likely to suffer population effects when exposed to longline fishing activity, followed by the larger petrels from the genuses Procellaria, Macronectes and Pterodroma. A mixture of coastal states with nesting seabird populations in their Exclusive Economic Zones (New Zealand, Australia and United States of America), distant water fishing nations (Japan, Taiwan) and flags of convenience (Vanuatu) contributed 90% of the risk to seabird populations. Recommendations include enhancing the level of fisheries observer monitoring in areas indicated as high to medium risk for seabird interactions, and consideration of spatial management tools, such as more intensive or more stringent seabird bycatch mitigation requirements in high- to medium-risk areas. The methods used, and similar studies conducted in the Atlantic Ocean could lead to improved targeting of monitoring resources, and greater specificity in the needs for seabird-mitigation measures. This will assist in reducing seabird mortality in longline fishing operations and with more effective use of resources for fishery managers in both domestic fisheries and RFMOs.
The valuable sea cucumber Holothuria scabra, known as 'sandfish', has potential for restocking. H... more The valuable sea cucumber Holothuria scabra, known as 'sandfish', has potential for restocking. However, there is little information available to determine the size of the no-take zones (NTZs) needed to protect the released animals so that they can form nucleus breeding populations. To do this, we measured short-term movement paths of released juvenile (1-105 g) and wild adult (130-690 g) sandfish in a seagrass bed in New Caledonia. We then developed an individual-based model (IBM) to predict long-term dispersal of sandfish released as juveniles (1-16 g) at 1 individual m −2 within a 1-ha area, drawing on distributions of speed and directionality and the relationship between speed and animal weight from field data. Movement was non-random at the sampling scale used, since animals tended to turn <90 • at each 2-h time step. We examined high-and low-growth scenarios by applying 50% and 25% of the modelled growth rates of sandfish held in earthen ponds (where they are known to grow faster). The dispersal of released sandfish was predicted to be limited in the first 2 years, then markedly faster thereafter. After 10 years, 6-12% of surviving animals were predicted to remain in the original 1-ha release site. To protect surviving sandfish as nucleus breeding populations for 10 years, and accepting 10% spillover, square NTZs would need to be 19-40 ha. The findings are useful for the management of restocking and pre-defining the size of sites for recapture surveys. Our model allows user-specified values for future releases and should be applicable for other sedentary marine invertebrates where basic data on movement and growth are available.
Different stock-recruitment models were fitted to North Atlantic albacore (Thunnus alalunga) recr... more Different stock-recruitment models were fitted to North Atlantic albacore (Thunnus alalunga) recruitment and spawning stock biomass data. A classical density dependence hypothesis, a recent environmental-dependence hypothesis and a combination of both were considered. For the latter case, four stockenvironment-recruitment models were used: Ricker, Beverton-Holt, Deriso's General Model (modified to take into account environmental effects) and conditioned Neural Networks. Cross-validation analysis showed that the modified Deriso model had the best predictive capability. It detected an inverse effect of the North Atlantic Oscillation (NAO) on recruitment, a Ricker-type behaviour with density dependent overcompensation when environmental conditions are unfavourable and a Beverton-Holt-type behaviour towards an asymptotic recruitment carrying capacity with favourable environmental conditions. The Neural Network model also detected that under favourable environmental conditions high spawning stock biomass does not necessarily have a depensatory effect on recruitment. Moreover, they suggest that under extremely favourable environmental conditions, albacore recruitment could increase well above the asymptotic carrying capacity predicted by Beverton-Holt-type models. However, the general decrease in spawning stock biomass in recent years and increasing NAO trends suggest that there is low probability of exceptionally large recruitment in the future and instead there is a danger of recruitment overfishing.
Functional group name Functional group description Justification Swordfish Large Xiphias gladius ... more Functional group name Functional group description Justification Swordfish Large Xiphias gladius Other billfish Large Istiophorus platypterus, Makaira indica, Makaira mazara, Tetrapturus audax, Tetrapturus angustirostris Blue shark Large Prionace glauca Other sharks Large Alopiidae, Carcharhinidae, Lamnidae, Sphyrnidae Bigeye tuna Thunnus obesus larger than class size/age/weight at 50% of maturity 124cm/3.85y-46.2months/43kg* Yellowfin tuna Thunnus albacares larger than class size/age/weight at 50% of maturity 120cm/2.25y-27months/33kg* Skipjack tuna Katsuwonus pelamis larger than class size/age/weight at 100% of maturity 43cm/0.75y-9months/1.6kg* Piscivorous fish Alepisauridae, Bramidae, Carangidae, Coryphaenidae, Gempylidae, wahoo Acanthocybium solandri, opah Lampris guttatus, small Scombridae Bycatch species of interest for ecosystem management but species by species information not available. Small billfish Small billfish, same species as large groups swordfish and other billfish Small sharks Small sharks, same species as large groups blue shark and other sharks Small bigeye tuna Thunnus obesus smaller than class size/age/weight at 50% of maturity 124cm/3.85y-46.2months/43kg and larger than 20cm/3 months/0.18kg* Small yellowfin tuna Thunnus albacares smaller than class size/age/weight at 50% of maturity 120cm/2.25y-27months/33kg and larger than 24cm/3 months/0.33kg* Small skipjack tuna Katsuwonus pelamis smaller than class size/age/weight at 100% of maturity 43cm/0.75y-9months/1.6kg and larger than 24cm/3 months/0.25kg* Baby SKJ Katsuwonus pelamis from hatching to recruitement = 0 to 3 months, smaller than 24cm/0.25kg* Additional group required to decrease the importance of cannibalism and balance the model Epipelagic forage
Electronic tagging and tracking in marine fisheries. …, 2001
... Ab-stract available: http://www.soest.hawaii.edu/PFRP/brill_afs.pdf Brill, RW, Block, BA, Bog... more ... Ab-stract available: http://www.soest.hawaii.edu/PFRP/brill_afs.pdf Brill, RW, Block, BA, Boggs, CH, Bigelow, KA, Freund, EV and Marcinek, DJ (1999) Horizontal ... Fielder, P., and Bernard, H. (1987) Tuna aggregation and feeding near fronts observed in satellite imagery. Cont. ...
Seamounts are habitats of considerable interest in terms of conservation and biodiversity, and in... more Seamounts are habitats of considerable interest in terms of conservation and biodiversity, and in terms of fisheries for bentho-pelagic and pelagic species. Twenty previously compiled datasets including seamount/underwater feature lists, bathymetric maps and emerged feature ...
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Papers by David Kirby