The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Jessica H. Farley - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH ARTICLE A Standardised Abundance Index from Commercial Spotting Data of Southern Bluefin Tuna (Thunnus maccoyii): Random Effects to the Rescue
2016Co-Authors: Marinelle Basson, Jessica H. FarleyAbstract:Commercial aerial spotting of surface schools of juvenile southern bluefin tuna (SBT), Thunnus maccoyii, is conducted as part of fishing operations in the Great Australian Bight in summer. This provides the opportunity to efficiently collect large amounts of data on sightings of SBT. The data can potentially be used to construct a time-series Index of relative Abundance by standardising the data for issues such as weather, spotter ability and ocean conditions. Unlike a statistically designed survey, the commercial spotting is governed by business considerations and fishing operations. The SBT dataset is therefore highly unbalanced with regard to spotters operating in each season. This complicates the standardisation of the data, particularly with regard to interactions between covariates. We show how a generalized additive model with random effects can simplify both the fitting of the model and the construction of an Index, while also avoiding the need to leave out strata or interaction terms that are important. The approach is applicable to standardisation of more traditional catch and effort data
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A Standardised Abundance Index from Commercial Spotting Data of Southern Bluefin Tuna (Thunnus maccoyii): Random Effects to the Rescue
PloS one, 2014Co-Authors: Marinelle Basson, Jessica H. FarleyAbstract:Commercial aerial spotting of surface schools of juvenile southern bluefin tuna (SBT), Thunnus maccoyii, is conducted as part of fishing operations in the Great Australian Bight in summer. This provides the opportunity to efficiently collect large amounts of data on sightings of SBT. The data can potentially be used to construct a time-series Index of relative Abundance by standardising the data for issues such as weather, spotter ability and ocean conditions. Unlike a statistically designed survey, the commercial spotting is governed by business considerations and fishing operations. The SBT dataset is therefore highly unbalanced with regard to spotters operating in each season. This complicates the standardisation of the data, particularly with regard to interactions between covariates. We show how a generalized additive model with random effects can simplify both the fitting of the model and the construction of an Index, while also avoiding the need to leave out strata or interaction terms that are important. The approach is applicable to standardisation of more traditional catch and effort data.
Marinelle Basson - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH ARTICLE A Standardised Abundance Index from Commercial Spotting Data of Southern Bluefin Tuna (Thunnus maccoyii): Random Effects to the Rescue
2016Co-Authors: Marinelle Basson, Jessica H. FarleyAbstract:Commercial aerial spotting of surface schools of juvenile southern bluefin tuna (SBT), Thunnus maccoyii, is conducted as part of fishing operations in the Great Australian Bight in summer. This provides the opportunity to efficiently collect large amounts of data on sightings of SBT. The data can potentially be used to construct a time-series Index of relative Abundance by standardising the data for issues such as weather, spotter ability and ocean conditions. Unlike a statistically designed survey, the commercial spotting is governed by business considerations and fishing operations. The SBT dataset is therefore highly unbalanced with regard to spotters operating in each season. This complicates the standardisation of the data, particularly with regard to interactions between covariates. We show how a generalized additive model with random effects can simplify both the fitting of the model and the construction of an Index, while also avoiding the need to leave out strata or interaction terms that are important. The approach is applicable to standardisation of more traditional catch and effort data
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A Standardised Abundance Index from Commercial Spotting Data of Southern Bluefin Tuna (Thunnus maccoyii): Random Effects to the Rescue
PloS one, 2014Co-Authors: Marinelle Basson, Jessica H. FarleyAbstract:Commercial aerial spotting of surface schools of juvenile southern bluefin tuna (SBT), Thunnus maccoyii, is conducted as part of fishing operations in the Great Australian Bight in summer. This provides the opportunity to efficiently collect large amounts of data on sightings of SBT. The data can potentially be used to construct a time-series Index of relative Abundance by standardising the data for issues such as weather, spotter ability and ocean conditions. Unlike a statistically designed survey, the commercial spotting is governed by business considerations and fishing operations. The SBT dataset is therefore highly unbalanced with regard to spotters operating in each season. This complicates the standardisation of the data, particularly with regard to interactions between covariates. We show how a generalized additive model with random effects can simplify both the fitting of the model and the construction of an Index, while also avoiding the need to leave out strata or interaction terms that are important. The approach is applicable to standardisation of more traditional catch and effort data.
Yongjun Tian - One of the best experts on this subject based on the ideXlab platform.
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synchrony in the Abundance trend of spear squid loligo bleekeri in the japan sea and the pacific ocean with special reference to the latitudinal differences in response to the climate regime shift
Ices Journal of Marine Science, 2013Co-Authors: Yongjun Tian, Kazuya Nashida, Hideo SakajiAbstract:Spear squid Loligo bleekeri is widely distributed in the Japanese coastal waters. The fisheries depend largely on four stocks: the southern and northern stocks both in the Japan Sea and the coastal regions of the Pacific. The catch per unit effort (cpue) for the northern stock in the Japan Sea decreased substantially during the 1980s but increased during the 1990s, while the Abundance Index for the southern stock showed the opposite trend. The cpue for the southern and northern stocks in the Pacific coast showed a similar pattern to that in the Japan Sea. The synchrony in the Abundance trends between the Japan Sea and the Pacific Ocean, and latitudinal differences between the northern and southern stocks indicate the impact of the climate regime shift. Generalized additive model analysis identified significant effects of environmental factors. Increased water temperature had a positive effect on the northern
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interannual interdecadal variations of spear squid loligo bleekeri Abundance in the southwestern japan sea during 1975 2006 impact of the trawl fishing and recommendations for management under the different climate regimes
Fisheries Research, 2009Co-Authors: Yongjun TianAbstract:A climatic regime shift, characterized by an abrupt change from cool to warm conditions, occurred in the Tsushima Warm Current (TWC) region in the Japan Sea in the late 1980s. The Abundance of spear squid Loligo bleekeri in the southwestern part of the Japan Sea responded strongly to the changing thermal regime. Spear squid are widely distributed in Japanese coastal waters and form one of the most important target species of pair trawlers in the southwestern Japan Sea. Catch from the southwestern Japan Sea has fluctuated from a minimum of 16 tons in 2003 to a maximum of 13,700 tons in 1977. Catch has decreased to less than 100 tons in recent years, and consequently the stock is at the point of collapse. The Abundance Index of spear squid shows a decadal pattern of variation with a step change from positive to negative annual anomalies that occurred around 1990; this pattern corresponds closely with the changing regime in water temperature in the TWC, strongly indicating that the decadal variability in spear squid was largely affected by the climatic regime shift in the late 1980s. Significant negative correlations between water temperature and an Abundance Index of spear squid (R 2 =0.39, p < 0.01) indicate that increasing ambient water temperature reduced spear squid Abundances during the 1990s. Monthly CPUE (catch per unit effort) decreases sharply during the fishing season from autumn through winter, a patterns that was well described by a DeLury model. DeLury estimates of apparent mortality showed that the fishing mortality coefficient was relatively stable during 1975-1987, but has increased greatly since the late 1980s. The average fishing mortality coefficient averaged during the warmer 1990s was about 2.1 times higher than during the colder late 1970s and 1980s, indicating that the fishing mortality has intensified during the 1990s and has accelerated the collapse of the stock. This suggests that the decadal pattern of variation of spear squid was largely forced by the late 1980s climatic regime shift of the TWC, while high fishing magnified interannual variation of spear squid and attributed to the subsequent collapse of the stock. Reducing fishing pressure on juvenile squid during the early part of the fishing season in autumn is considered to be particularly important for the recovery of this stock under the current unfavorable thermal regime.
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development of method for estimation of 0 fish Abundance Index of jack mackerel trachurus japonicus by mid water trawling and area swept method in the southwestern sea of japan
Nippon Suisan Gakkaishi, 2009Co-Authors: Tsuyoshi Shimura, Seiji Ohshimo, Hiroyoshi Terakado, Yongjun TianAbstract:マアジは日本周辺の沿岸域に広く分布する産業重要種である。マアジ対馬暖流系群の資源量は VPA 法で推定されているが，この手法では当歳魚の資源量が推定されるのは加入から数年後であるため，当歳魚の資源評価の精度が低いという欠点がある。そこで，漁期前に中層トロールで当歳魚を採集して，面積密度法によって現存量指標値を推定する方法を開発した。マアジの分布は水塊配置によって東西や南北方向に偏った。面積密度法によって水温分布を考慮し 4 海域に区分することで，正確な現存量指標値を推定することができた。
Mark N Maunder - One of the best experts on this subject based on the ideXlab platform.
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data reconstruction can improve Abundance Index estimation an example using taiwanese longline data for pacific bluefin tuna
PLOS ONE, 2017Co-Authors: Shuikai Chang, Hiromu Fukuda, Mark N MaunderAbstract:Catch-per-unit-effort (CPUE) is often the main piece of information used in fisheries stock assessment; however, the catch and effort data that are traditionally compiled from commercial logbooks can be incomplete or unreliable due to many reasons. Pacific bluefin tuna (PBF) is a seasonal target species in the Taiwanese longline fishery. Since 2010, detailed catch information for each PBF has been made available through a catch documentation scheme. However, previously, only market landing data with a low coverage of logbooks were available. Therefore, several nontraditional procedures were performed to reconstruct catch and effort data from many alternative data sources not directly obtained from fishers for 2001–2015: (1) Estimating the catch number from the landing weight for 2001–2003, for which the catch number information was incomplete, based on Monte Carlo simulation; (2) deriving fishing days for 2007–2009 from voyage data recorder data, based on a newly developed algorithm; and (3) deriving fishing days for 2001–2006 from vessel trip information, based on linear relationships between fishing and at-sea days. Subsequently, generalized linear mixed models were developed with the delta-lognormal assumption for standardizing the CPUE calculated from the reconstructed data, and three-stage model evaluation was performed using (1) Akaike and Bayesian information criteria to determine the most favorable variable composition of standardization models, (2) overall R2 via cross-validation to compare fitting performance between area-separated and area-combined standardizations, and (3) system-based testing to explore the consistency of the standardized CPUEs with auxiliary data in the PBF stock assessment model. The last stage of evaluation revealed high consistency among the data, thus demonstrating improvements in data reconstruction for estimating the Abundance Index, and consequently the stock assessment.
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evaluation of virgin recruitment profiling as a diagnostic for selectivity curve structure in integrated stock assessment models
Fisheries Research, 2014Co-Authors: Mark N Maunder, Shengping Wang, Kevin R Piner, Alexandre AiresdasilvaAbstract:Abstract Virgin recruitment (R0), the equilibrium recruitment in the absence of fishing, is an often used parameter in fisheries stock assessment for scaling population size. We describe and evaluate the use of the R0 likelihood component profile to diagnose selectivity misspecification, using simulation analysis for bigeye tuna in the eastern Pacific Ocean. The profile is evaluated under two types of selectivity misspecification: (1) misspecified shape and (2) misspecified temporal variation. The results indicate that length-composition data can provide substantial information on R0 estimation when the model is correctly specified, but can substantially bias estimates of absolute Abundance when selectivity is misspecified. Although contradictory profiles for length-composition and Abundance Index data result from selectivity misspecification, they may not be useful in determining which survey or fishery selectivity is misspecified. The R0 profile selectivity diagnostic is based on the influence of composition data on absolute Abundance. However, perhaps a more problematic and difficult to detect issue is the impact of length-composition data on biomass trends. The age-structured production model diagnostic could be applied to identify bias in both absolute biomass and biomass trend caused by age- or length-composition data in the presence of model misspecification.
Hideo Sakaji - One of the best experts on this subject based on the ideXlab platform.
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synchrony in the Abundance trend of spear squid loligo bleekeri in the japan sea and the pacific ocean with special reference to the latitudinal differences in response to the climate regime shift
Ices Journal of Marine Science, 2013Co-Authors: Yongjun Tian, Kazuya Nashida, Hideo SakajiAbstract:Spear squid Loligo bleekeri is widely distributed in the Japanese coastal waters. The fisheries depend largely on four stocks: the southern and northern stocks both in the Japan Sea and the coastal regions of the Pacific. The catch per unit effort (cpue) for the northern stock in the Japan Sea decreased substantially during the 1980s but increased during the 1990s, while the Abundance Index for the southern stock showed the opposite trend. The cpue for the southern and northern stocks in the Pacific coast showed a similar pattern to that in the Japan Sea. The synchrony in the Abundance trends between the Japan Sea and the Pacific Ocean, and latitudinal differences between the northern and southern stocks indicate the impact of the climate regime shift. Generalized additive model analysis identified significant effects of environmental factors. Increased water temperature had a positive effect on the northern