2009 - 2010 Halibut Debate + Poll
- Thread starter the fog ducker
- Start date
i am in the midst of reading through the analysis of the 2008 data collection. from page 6 of that report:
"Estimates of uncertainty
There are a number of ways of estimating the uncertainty associated with a given model fit and biomass estimate. They are all unsatisfactory in that they are conditioned on the correctness
of the model, and in fact it is the choice of one model rather than another that is the major source of uncertainty in assessments. This is well illustrated by the difference in area-specific biomass
estimates between the coastwide and closed-area fits of the IPHC model. One standard method of illustrating uncertainty around an estimate, for a given model, is the likelihood profile. The bottom panels in Figure 14 show the likelihood profile for both the exploitable biomass as well as the female spawning biomass. The 95% confidence interval (C.I.) for EBio is 286 to 368 million pounds, while the 95% C.I. for the female spawning biomass is 274 to 359 million pounds. Confidence intervals for the recruitment estimates were also computed and are plotted with the recruitment estimates (Fig. 14, top panel).
Retrospective performance
Each year’s model fit estimates the abundance and other parameters for all years in the data series. One hopes that the present assessment will closely match the biomass trajectory estimated by the previous year’s assessment. To the extent that it does not, the assessment is said to have poor retrospective performance. Our assessment has not tracked very well for the last few years. Each year the assessment has revised downward the previous year’s biomass estimates (Fig. 15a), meaning that biomass was overestimated then and may be overestimated now if the cause of the retrospective problem lies somewhere within the model..."
so as you assume that halibut populations are ok, you need to understand that the IPHC estimates are based on a statistical model that is not predicting outcomes very well. you will also note that they used the upper numbers (see the C.I. #s) for 'exploitable biomass', same as WDFW using MSY to inflate commercial harvest.
so if i were thinking about this, and i certainly will continue slugging my way though their data, i would NOT be making the assumption that all is rosy in the pacific. the reading is interesting and i am sure these folks are doing the best they can with prediction but you must keep in mind that statistical predictions, with any degree of accuracy, require understanding the total extent of variables impinging on the model, an impossibility with fisheries management. in WA, the statistical prediction model has been off, annually, somewhere in the range of 50-75%. that is, way too many fish have been declared avaiable for harvest.
again, go back and look at the C.I. #s and compare those to the TAC. see any similarity?
"Estimates of uncertainty
There are a number of ways of estimating the uncertainty associated with a given model fit and biomass estimate. They are all unsatisfactory in that they are conditioned on the correctness
of the model, and in fact it is the choice of one model rather than another that is the major source of uncertainty in assessments. This is well illustrated by the difference in area-specific biomass
estimates between the coastwide and closed-area fits of the IPHC model. One standard method of illustrating uncertainty around an estimate, for a given model, is the likelihood profile. The bottom panels in Figure 14 show the likelihood profile for both the exploitable biomass as well as the female spawning biomass. The 95% confidence interval (C.I.) for EBio is 286 to 368 million pounds, while the 95% C.I. for the female spawning biomass is 274 to 359 million pounds. Confidence intervals for the recruitment estimates were also computed and are plotted with the recruitment estimates (Fig. 14, top panel).
Retrospective performance
Each year’s model fit estimates the abundance and other parameters for all years in the data series. One hopes that the present assessment will closely match the biomass trajectory estimated by the previous year’s assessment. To the extent that it does not, the assessment is said to have poor retrospective performance. Our assessment has not tracked very well for the last few years. Each year the assessment has revised downward the previous year’s biomass estimates (Fig. 15a), meaning that biomass was overestimated then and may be overestimated now if the cause of the retrospective problem lies somewhere within the model..."
so as you assume that halibut populations are ok, you need to understand that the IPHC estimates are based on a statistical model that is not predicting outcomes very well. you will also note that they used the upper numbers (see the C.I. #s) for 'exploitable biomass', same as WDFW using MSY to inflate commercial harvest.
so if i were thinking about this, and i certainly will continue slugging my way though their data, i would NOT be making the assumption that all is rosy in the pacific. the reading is interesting and i am sure these folks are doing the best they can with prediction but you must keep in mind that statistical predictions, with any degree of accuracy, require understanding the total extent of variables impinging on the model, an impossibility with fisheries management. in WA, the statistical prediction model has been off, annually, somewhere in the range of 50-75%. that is, way too many fish have been declared avaiable for harvest.
again, go back and look at the C.I. #s and compare those to the TAC. see any similarity?
i am in the midst of reading through the analysis of the 2008 data collection. from page 6 of that report:
"Estimates of uncertainty
There are a number of ways of estimating the uncertainty associated with a given model fit and biomass estimate. They are all unsatisfactory in that they are conditioned on the correctness
of the model, and in fact it is the choice of one model rather than another that is the major source of uncertainty in assessments. This is well illustrated by the difference in area-specific biomass
estimates between the coastwide and closed-area fits of the IPHC model. One standard method of illustrating uncertainty around an estimate, for a given model, is the likelihood profile. The bottom panels in Figure 14 show the likelihood profile for both the exploitable biomass as well as the female spawning biomass. The 95% confidence interval (C.I.) for EBio is 286 to 368 million pounds, while the 95% C.I. for the female spawning biomass is 274 to 359 million pounds. Confidence intervals for the recruitment estimates were also computed and are plotted with the recruitment estimates (Fig. 14, top panel).
Retrospective performance
Each year’s model fit estimates the abundance and other parameters for all years in the data series. One hopes that the present assessment will closely match the biomass trajectory estimated by the previous year’s assessment. To the extent that it does not, the assessment is said to have poor retrospective performance. Our assessment has not tracked very well for the last few years. Each year the assessment has revised downward the previous year’s biomass estimates (Fig. 15a), meaning that biomass was overestimated then and may be overestimated now if the cause of the retrospective problem lies somewhere within the model..."
so as you assume that halibut populations are ok, you need to understand that the IPHC estimates are based on a statistical model that is not predicting outcomes very well. you will also note that they used the upper numbers (see the C.I. #s) for 'exploitable biomass', same as WDFW using MSY to inflate commercial harvest.
so if i were thinking about this, and i certainly will continue slugging my way though their data, i would NOT be making the assumption that all is rosy in the pacific. the reading is interesting and i am sure these folks are doing the best they can with prediction but you must keep in mind that statistical predictions, with any degree of accuracy, require understanding the total extent of variables impinging on the model, an impossibility with fisheries management. in WA, the statistical prediction model has been off, annually, somewhere in the range of 50-75%. that is, way too many fish have been declared avaiable for harvest.
again, go back and look at the C.I. #s and compare those to the TAC. see any similarity?
"Estimates of uncertainty
There are a number of ways of estimating the uncertainty associated with a given model fit and biomass estimate. They are all unsatisfactory in that they are conditioned on the correctness
of the model, and in fact it is the choice of one model rather than another that is the major source of uncertainty in assessments. This is well illustrated by the difference in area-specific biomass
estimates between the coastwide and closed-area fits of the IPHC model. One standard method of illustrating uncertainty around an estimate, for a given model, is the likelihood profile. The bottom panels in Figure 14 show the likelihood profile for both the exploitable biomass as well as the female spawning biomass. The 95% confidence interval (C.I.) for EBio is 286 to 368 million pounds, while the 95% C.I. for the female spawning biomass is 274 to 359 million pounds. Confidence intervals for the recruitment estimates were also computed and are plotted with the recruitment estimates (Fig. 14, top panel).
Retrospective performance
Each year’s model fit estimates the abundance and other parameters for all years in the data series. One hopes that the present assessment will closely match the biomass trajectory estimated by the previous year’s assessment. To the extent that it does not, the assessment is said to have poor retrospective performance. Our assessment has not tracked very well for the last few years. Each year the assessment has revised downward the previous year’s biomass estimates (Fig. 15a), meaning that biomass was overestimated then and may be overestimated now if the cause of the retrospective problem lies somewhere within the model..."
so as you assume that halibut populations are ok, you need to understand that the IPHC estimates are based on a statistical model that is not predicting outcomes very well. you will also note that they used the upper numbers (see the C.I. #s) for 'exploitable biomass', same as WDFW using MSY to inflate commercial harvest.
so if i were thinking about this, and i certainly will continue slugging my way though their data, i would NOT be making the assumption that all is rosy in the pacific. the reading is interesting and i am sure these folks are doing the best they can with prediction but you must keep in mind that statistical predictions, with any degree of accuracy, require understanding the total extent of variables impinging on the model, an impossibility with fisheries management. in WA, the statistical prediction model has been off, annually, somewhere in the range of 50-75%. that is, way too many fish have been declared avaiable for harvest.
again, go back and look at the C.I. #s and compare those to the TAC. see any similarity?
the fog ducker
Well-Known Member
x2
Gov knows his Shyte !!
Just outta curiosity , how many fish do ya think make it back to Neah ( hali ), from our waters ??[B)] ..anyone know ?? I'll be honest , did not see many Washington , Oregon , tags outta Barkley this season , guessing most of them are fishing Swift ...
...FD
kosi99@hotmail.com
Gov knows his Shyte !!
Just outta curiosity , how many fish do ya think make it back to Neah ( hali ), from our waters ??[B)] ..anyone know ?? I'll be honest , did not see many Washington , Oregon , tags outta Barkley this season , guessing most of them are fishing Swift ...
...FDkosi99@hotmail.com
the fog ducker
Well-Known Member
x2
Gov knows his Shyte !!
Just outta curiosity , how many fish do ya think make it back to Neah ( hali ), from our waters ??[B)] ..anyone know ?? I'll be honest , did not see many Washington , Oregon , tags outta Barkley this season , guessing most of them are fishing Swift ......FD
kosi99@hotmail.com
Gov knows his Shyte !!
Just outta curiosity , how many fish do ya think make it back to Neah ( hali ), from our waters ??[B)] ..anyone know ?? I'll be honest , did not see many Washington , Oregon , tags outta Barkley this season , guessing most of them are fishing Swift ...
...FDkosi99@hotmail.com
Chris I agree we should have a full season March 1st to Dec 31st and the 88-12 has to go...but I'm still set in MY mind that no-one needs more than 10 and it should be a regulation. By the way I'm involved in the process...but that doesn't mean I have to tow the party line so to speak I will continue to think for myself while I'm still able to!
Chris I agree we should have a full season March 1st to Dec 31st and the 88-12 has to go...but I'm still set in MY mind that no-one needs more than 10 and it should be a regulation. By the way I'm involved in the process...but that doesn't mean I have to tow the party line so to speak I will continue to think for myself while I'm still able to!
unknown, i would have to go back to the statistical model that is currently being used to determine the EBio. as you can see from the numbers contained in that 2008 assessment, there is quite a gap, high to low. if i were making a decision regarding tonage available for harvest, i would automatically choose the smaller number. in the case summarized via this report, 274 million pounds.
the allocation between vested interests becomes a seperate issue but one that is more than likely driven by money. therefore, it is no surprise to me that the vast majority of the EBio is handed over to commercial interests, as has been underscored in this thread.
i do believe, however, that when a flawed statistical model, note they admit the model's poor performance, is used to determine the EBio and then the larger of the EBio predictions is choosen for distribution to end users, you are shopping for a stock collapse.
what has been learned from anadramous fishes is there is a certain number of carry forward fish necessary to simply maintain statis quo. it is virtually impossible to determine an exact # so the logical management thing to do is err on the conservative number side and reduce harvest numbers. that is not what 'fisheries managers' choose to do, year after year, decade after decade, the biggest take always wins out and is then proclaimed to be a safe sustainable number. although in the case of halibut management, they have reduced the take numbers over the last few years. enough? that is a tough one to answer. but from the model the larger EBio numbers seem to win out, not a good management scenario but one that greases the commercial lobby wheels.
as i continue through this 65 page jargon filled assessment, i'll point out anything else that jumps up at me. and, please, if i am not interpreting these statement correctly, feel free to point that out, i still put my pants on one leg at a time just like you
the allocation between vested interests becomes a seperate issue but one that is more than likely driven by money. therefore, it is no surprise to me that the vast majority of the EBio is handed over to commercial interests, as has been underscored in this thread.
i do believe, however, that when a flawed statistical model, note they admit the model's poor performance, is used to determine the EBio and then the larger of the EBio predictions is choosen for distribution to end users, you are shopping for a stock collapse.
what has been learned from anadramous fishes is there is a certain number of carry forward fish necessary to simply maintain statis quo. it is virtually impossible to determine an exact # so the logical management thing to do is err on the conservative number side and reduce harvest numbers. that is not what 'fisheries managers' choose to do, year after year, decade after decade, the biggest take always wins out and is then proclaimed to be a safe sustainable number. although in the case of halibut management, they have reduced the take numbers over the last few years. enough? that is a tough one to answer. but from the model the larger EBio numbers seem to win out, not a good management scenario but one that greases the commercial lobby wheels.
as i continue through this 65 page jargon filled assessment, i'll point out anything else that jumps up at me. and, please, if i am not interpreting these statement correctly, feel free to point that out, i still put my pants on one leg at a time just like you
unknown, i would have to go back to the statistical model that is currently being used to determine the EBio. as you can see from the numbers contained in that 2008 assessment, there is quite a gap, high to low. if i were making a decision regarding tonage available for harvest, i would automatically choose the smaller number. in the case summarized via this report, 274 million pounds.
the allocation between vested interests becomes a seperate issue but one that is more than likely driven by money. therefore, it is no surprise to me that the vast majority of the EBio is handed over to commercial interests, as has been underscored in this thread.
i do believe, however, that when a flawed statistical model, note they admit the model's poor performance, is used to determine the EBio and then the larger of the EBio predictions is choosen for distribution to end users, you are shopping for a stock collapse.
what has been learned from anadramous fishes is there is a certain number of carry forward fish necessary to simply maintain statis quo. it is virtually impossible to determine an exact # so the logical management thing to do is err on the conservative number side and reduce harvest numbers. that is not what 'fisheries managers' choose to do, year after year, decade after decade, the biggest take always wins out and is then proclaimed to be a safe sustainable number. although in the case of halibut management, they have reduced the take numbers over the last few years. enough? that is a tough one to answer. but from the model the larger EBio numbers seem to win out, not a good management scenario but one that greases the commercial lobby wheels.
as i continue through this 65 page jargon filled assessment, i'll point out anything else that jumps up at me. and, please, if i am not interpreting these statement correctly, feel free to point that out, i still put my pants on one leg at a time just like you
the allocation between vested interests becomes a seperate issue but one that is more than likely driven by money. therefore, it is no surprise to me that the vast majority of the EBio is handed over to commercial interests, as has been underscored in this thread.
i do believe, however, that when a flawed statistical model, note they admit the model's poor performance, is used to determine the EBio and then the larger of the EBio predictions is choosen for distribution to end users, you are shopping for a stock collapse.
what has been learned from anadramous fishes is there is a certain number of carry forward fish necessary to simply maintain statis quo. it is virtually impossible to determine an exact # so the logical management thing to do is err on the conservative number side and reduce harvest numbers. that is not what 'fisheries managers' choose to do, year after year, decade after decade, the biggest take always wins out and is then proclaimed to be a safe sustainable number. although in the case of halibut management, they have reduced the take numbers over the last few years. enough? that is a tough one to answer. but from the model the larger EBio numbers seem to win out, not a good management scenario but one that greases the commercial lobby wheels.
as i continue through this 65 page jargon filled assessment, i'll point out anything else that jumps up at me. and, please, if i am not interpreting these statement correctly, feel free to point that out, i still put my pants on one leg at a time just like you
Reelfast,
Credit to you for doing the reading and oh boy, it's dry stuff to wade through too. But being informed gets us all quickly to the key factors when discussions begin. Kudos.
In Canada there are certain salmon stocks that are not only in precipitous decline but are also suffering as much as 70% fishing mortality annually within in mixed stock fisheries where other stocks are somewhat abundant. This is apparently due to "management" being too fearful of the consequences of closing down the fishery in order to allow that stock to rebound. What this essentially amounts to is knowingly promoting exterpation and extinction which is just unacceptable.
Gov
God never did make a more calm, quiet, innocent recreation than angling - Izaak Walton
Credit to you for doing the reading and oh boy, it's dry stuff to wade through too. But being informed gets us all quickly to the key factors when discussions begin. Kudos.
In Canada there are certain salmon stocks that are not only in precipitous decline but are also suffering as much as 70% fishing mortality annually within in mixed stock fisheries where other stocks are somewhat abundant. This is apparently due to "management" being too fearful of the consequences of closing down the fishery in order to allow that stock to rebound. What this essentially amounts to is knowingly promoting exterpation and extinction which is just unacceptable.
Gov
God never did make a more calm, quiet, innocent recreation than angling - Izaak Walton
Reelfast,
Credit to you for doing the reading and oh boy, it's dry stuff to wade through too. But being informed gets us all quickly to the key factors when discussions begin. Kudos.
In Canada there are certain salmon stocks that are not only in precipitous decline but are also suffering as much as 70% fishing mortality annually within in mixed stock fisheries where other stocks are somewhat abundant. This is apparently due to "management" being too fearful of the consequences of closing down the fishery in order to allow that stock to rebound. What this essentially amounts to is knowingly promoting exterpation and extinction which is just unacceptable.
Gov
God never did make a more calm, quiet, innocent recreation than angling - Izaak Walton
Credit to you for doing the reading and oh boy, it's dry stuff to wade through too. But being informed gets us all quickly to the key factors when discussions begin. Kudos.
In Canada there are certain salmon stocks that are not only in precipitous decline but are also suffering as much as 70% fishing mortality annually within in mixed stock fisheries where other stocks are somewhat abundant. This is apparently due to "management" being too fearful of the consequences of closing down the fishery in order to allow that stock to rebound. What this essentially amounts to is knowingly promoting exterpation and extinction which is just unacceptable.
Gov
God never did make a more calm, quiet, innocent recreation than angling - Izaak Walton
from p 13:
" Area summaries
The coastwide assessment indicates that the exploitable biomass of halibut has declined approximately 50% over the past decade. This declining trend is seen almost all of the area-specific survey and commercial CPUE indices. But the breadth and reasons behind the declines vary by area..."
the area by area analysis follows that opening statement. once i figure out 'our' areas, i'll post their rationale for the declines.
" Area summaries
The coastwide assessment indicates that the exploitable biomass of halibut has declined approximately 50% over the past decade. This declining trend is seen almost all of the area-specific survey and commercial CPUE indices. But the breadth and reasons behind the declines vary by area..."
the area by area analysis follows that opening statement. once i figure out 'our' areas, i'll post their rationale for the declines.
from p 13:
" Area summaries
The coastwide assessment indicates that the exploitable biomass of halibut has declined approximately 50% over the past decade. This declining trend is seen almost all of the area-specific survey and commercial CPUE indices. But the breadth and reasons behind the declines vary by area..."
the area by area analysis follows that opening statement. once i figure out 'our' areas, i'll post their rationale for the declines.
" Area summaries
The coastwide assessment indicates that the exploitable biomass of halibut has declined approximately 50% over the past decade. This declining trend is seen almost all of the area-specific survey and commercial CPUE indices. But the breadth and reasons behind the declines vary by area..."
the area by area analysis follows that opening statement. once i figure out 'our' areas, i'll post their rationale for the declines.
had to back track to another set of technical papers by the IPHC but here are the areas of interest:
generally area 2, subdivided as 2A coastal us up to mouth of the strait at tatoosh isl; 2B WCVI up to charlettes including the entire strait, puget sound and the inside canadian waters; 2C up to AK waters.
summary for area 2:
" Area 2
Area 2A, 2B and 2C indices are illustrated in Figures 26, 27 and 28, respectively. Between 1997 and 2006, total removals were stable in all three areas, averaging 1.6 million pounds in Area 2A, 13.5 million pounds in Area 2B and 12.4 million pounds in Area 2C. Removals declined sharply in 2007 and 2008, in response to the revised view of relative halibut abundance in Area 2. Sublegal bycatch, and subsequent lost yield to the sport and commercial fisheries, is estimated to be rather low, though legal-sized bycatch in Area 2A still represents a sizable portion of total removals. Surplus production estimates suggest that removals have exceeded surplus production in Area 2 for most of the past decade.</u> Commercial effort has steadily increased in Area 2A for almost a decade but was relatively level in Areas 2B and 2C, and in fact declined over the past two years. Indices of abundance all suggest a steady decline in biomass in all three areas, though the Area 2B survey setline CPUE increased nearly 50% in 2008. All three areas saw decline of more than 50% in survey CPUE between 1996 and 2007, and declines continued for 2A and 2C. As is the case with the coastwide estimate of abundance, a small increase in EBio is projected for the beginning of 2009. The age structure of fish caught in Area 2 is noticeably younger than in Areas 3 and 4. Mean age is around 11 years of age, with little difference between males and females. All the indices are consistent with a picture of a steadily declining exploitable biomass in Area 2. The reasons for the decline are likely twofold. The first is the passing through of the two very large year classes of 1987 and 1988. Every assessment over the past decade has shown that those two year classes were very strong in comparison to the surrounding year classes. Now that those two year classes are 20 years old, their contribution to the exploitable biomass and catches has sharply declined and the drop in biomass is to be expected as they are replaced by year classes of lesser magnitude. Removals have been generally larger than surplus production and this prevents rebuilding of regional stocks. Our present view of Area 2 is that harvest rates have been much higher than the target rate of 0.20 over the past decade and are not sustainable, particularly with the passage of the 1987 and 1988 year classes.</u>There are signs that two or three large year classes are
set to enter the exploitable biomass, however, the exploitable biomass will not increase as long as harvest rates remain high. Finally, Area 2 presently accounts for 28% of total removals coastwide but contributes just 17% to the female spawning biomass, a byproduct of the young age of the resident population..."
(i added the underscores)
arguing that there is no problem with halibut stocks in our immediate areas seems to argue against the data, no matter how statistically off it may be. it is also interesting to note that the IPHC has been refining it's data collection models and has incorporated a couple of features to try and tune it a bit tighter. that may help in future stock projections, but only time will tell as all of this is reviewed after the fact.
the bottom line here folks is the halibut stocks are declining, the numbers of large fish are seriously declining, the numbers of spawner females is declining and the number of male fish are undersized (32" being the commercial cut off).
thanks, governor, for pointing me to this web site, it is packed full of 'put you to sleep reports'. [8D]
generally area 2, subdivided as 2A coastal us up to mouth of the strait at tatoosh isl; 2B WCVI up to charlettes including the entire strait, puget sound and the inside canadian waters; 2C up to AK waters.
summary for area 2:
" Area 2
Area 2A, 2B and 2C indices are illustrated in Figures 26, 27 and 28, respectively. Between 1997 and 2006, total removals were stable in all three areas, averaging 1.6 million pounds in Area 2A, 13.5 million pounds in Area 2B and 12.4 million pounds in Area 2C. Removals declined sharply in 2007 and 2008, in response to the revised view of relative halibut abundance in Area 2. Sublegal bycatch, and subsequent lost yield to the sport and commercial fisheries, is estimated to be rather low, though legal-sized bycatch in Area 2A still represents a sizable portion of total removals. Surplus production estimates suggest that removals have exceeded surplus production in Area 2 for most of the past decade.</u> Commercial effort has steadily increased in Area 2A for almost a decade but was relatively level in Areas 2B and 2C, and in fact declined over the past two years. Indices of abundance all suggest a steady decline in biomass in all three areas, though the Area 2B survey setline CPUE increased nearly 50% in 2008. All three areas saw decline of more than 50% in survey CPUE between 1996 and 2007, and declines continued for 2A and 2C. As is the case with the coastwide estimate of abundance, a small increase in EBio is projected for the beginning of 2009. The age structure of fish caught in Area 2 is noticeably younger than in Areas 3 and 4. Mean age is around 11 years of age, with little difference between males and females. All the indices are consistent with a picture of a steadily declining exploitable biomass in Area 2. The reasons for the decline are likely twofold. The first is the passing through of the two very large year classes of 1987 and 1988. Every assessment over the past decade has shown that those two year classes were very strong in comparison to the surrounding year classes. Now that those two year classes are 20 years old, their contribution to the exploitable biomass and catches has sharply declined and the drop in biomass is to be expected as they are replaced by year classes of lesser magnitude. Removals have been generally larger than surplus production and this prevents rebuilding of regional stocks. Our present view of Area 2 is that harvest rates have been much higher than the target rate of 0.20 over the past decade and are not sustainable, particularly with the passage of the 1987 and 1988 year classes.</u>There are signs that two or three large year classes are
set to enter the exploitable biomass, however, the exploitable biomass will not increase as long as harvest rates remain high. Finally, Area 2 presently accounts for 28% of total removals coastwide but contributes just 17% to the female spawning biomass, a byproduct of the young age of the resident population..."
(i added the underscores)
arguing that there is no problem with halibut stocks in our immediate areas seems to argue against the data, no matter how statistically off it may be. it is also interesting to note that the IPHC has been refining it's data collection models and has incorporated a couple of features to try and tune it a bit tighter. that may help in future stock projections, but only time will tell as all of this is reviewed after the fact.
the bottom line here folks is the halibut stocks are declining, the numbers of large fish are seriously declining, the numbers of spawner females is declining and the number of male fish are undersized (32" being the commercial cut off).
thanks, governor, for pointing me to this web site, it is packed full of 'put you to sleep reports'. [8D]
had to back track to another set of technical papers by the IPHC but here are the areas of interest:
generally area 2, subdivided as 2A coastal us up to mouth of the strait at tatoosh isl; 2B WCVI up to charlettes including the entire strait, puget sound and the inside canadian waters; 2C up to AK waters.
summary for area 2:
" Area 2
Area 2A, 2B and 2C indices are illustrated in Figures 26, 27 and 28, respectively. Between 1997 and 2006, total removals were stable in all three areas, averaging 1.6 million pounds in Area 2A, 13.5 million pounds in Area 2B and 12.4 million pounds in Area 2C. Removals declined sharply in 2007 and 2008, in response to the revised view of relative halibut abundance in Area 2. Sublegal bycatch, and subsequent lost yield to the sport and commercial fisheries, is estimated to be rather low, though legal-sized bycatch in Area 2A still represents a sizable portion of total removals. Surplus production estimates suggest that removals have exceeded surplus production in Area 2 for most of the past decade.</u> Commercial effort has steadily increased in Area 2A for almost a decade but was relatively level in Areas 2B and 2C, and in fact declined over the past two years. Indices of abundance all suggest a steady decline in biomass in all three areas, though the Area 2B survey setline CPUE increased nearly 50% in 2008. All three areas saw decline of more than 50% in survey CPUE between 1996 and 2007, and declines continued for 2A and 2C. As is the case with the coastwide estimate of abundance, a small increase in EBio is projected for the beginning of 2009. The age structure of fish caught in Area 2 is noticeably younger than in Areas 3 and 4. Mean age is around 11 years of age, with little difference between males and females. All the indices are consistent with a picture of a steadily declining exploitable biomass in Area 2. The reasons for the decline are likely twofold. The first is the passing through of the two very large year classes of 1987 and 1988. Every assessment over the past decade has shown that those two year classes were very strong in comparison to the surrounding year classes. Now that those two year classes are 20 years old, their contribution to the exploitable biomass and catches has sharply declined and the drop in biomass is to be expected as they are replaced by year classes of lesser magnitude. Removals have been generally larger than surplus production and this prevents rebuilding of regional stocks. Our present view of Area 2 is that harvest rates have been much higher than the target rate of 0.20 over the past decade and are not sustainable, particularly with the passage of the 1987 and 1988 year classes.</u>There are signs that two or three large year classes are
set to enter the exploitable biomass, however, the exploitable biomass will not increase as long as harvest rates remain high. Finally, Area 2 presently accounts for 28% of total removals coastwide but contributes just 17% to the female spawning biomass, a byproduct of the young age of the resident population..."
(i added the underscores)
arguing that there is no problem with halibut stocks in our immediate areas seems to argue against the data, no matter how statistically off it may be. it is also interesting to note that the IPHC has been refining it's data collection models and has incorporated a couple of features to try and tune it a bit tighter. that may help in future stock projections, but only time will tell as all of this is reviewed after the fact.
the bottom line here folks is the halibut stocks are declining, the numbers of large fish are seriously declining, the numbers of spawner females is declining and the number of male fish are undersized (32" being the commercial cut off).
thanks, governor, for pointing me to this web site, it is packed full of 'put you to sleep reports'. [8D]
generally area 2, subdivided as 2A coastal us up to mouth of the strait at tatoosh isl; 2B WCVI up to charlettes including the entire strait, puget sound and the inside canadian waters; 2C up to AK waters.
summary for area 2:
" Area 2
Area 2A, 2B and 2C indices are illustrated in Figures 26, 27 and 28, respectively. Between 1997 and 2006, total removals were stable in all three areas, averaging 1.6 million pounds in Area 2A, 13.5 million pounds in Area 2B and 12.4 million pounds in Area 2C. Removals declined sharply in 2007 and 2008, in response to the revised view of relative halibut abundance in Area 2. Sublegal bycatch, and subsequent lost yield to the sport and commercial fisheries, is estimated to be rather low, though legal-sized bycatch in Area 2A still represents a sizable portion of total removals. Surplus production estimates suggest that removals have exceeded surplus production in Area 2 for most of the past decade.</u> Commercial effort has steadily increased in Area 2A for almost a decade but was relatively level in Areas 2B and 2C, and in fact declined over the past two years. Indices of abundance all suggest a steady decline in biomass in all three areas, though the Area 2B survey setline CPUE increased nearly 50% in 2008. All three areas saw decline of more than 50% in survey CPUE between 1996 and 2007, and declines continued for 2A and 2C. As is the case with the coastwide estimate of abundance, a small increase in EBio is projected for the beginning of 2009. The age structure of fish caught in Area 2 is noticeably younger than in Areas 3 and 4. Mean age is around 11 years of age, with little difference between males and females. All the indices are consistent with a picture of a steadily declining exploitable biomass in Area 2. The reasons for the decline are likely twofold. The first is the passing through of the two very large year classes of 1987 and 1988. Every assessment over the past decade has shown that those two year classes were very strong in comparison to the surrounding year classes. Now that those two year classes are 20 years old, their contribution to the exploitable biomass and catches has sharply declined and the drop in biomass is to be expected as they are replaced by year classes of lesser magnitude. Removals have been generally larger than surplus production and this prevents rebuilding of regional stocks. Our present view of Area 2 is that harvest rates have been much higher than the target rate of 0.20 over the past decade and are not sustainable, particularly with the passage of the 1987 and 1988 year classes.</u>There are signs that two or three large year classes are
set to enter the exploitable biomass, however, the exploitable biomass will not increase as long as harvest rates remain high. Finally, Area 2 presently accounts for 28% of total removals coastwide but contributes just 17% to the female spawning biomass, a byproduct of the young age of the resident population..."
(i added the underscores)
arguing that there is no problem with halibut stocks in our immediate areas seems to argue against the data, no matter how statistically off it may be. it is also interesting to note that the IPHC has been refining it's data collection models and has incorporated a couple of features to try and tune it a bit tighter. that may help in future stock projections, but only time will tell as all of this is reviewed after the fact.
the bottom line here folks is the halibut stocks are declining, the numbers of large fish are seriously declining, the numbers of spawner females is declining and the number of male fish are undersized (32" being the commercial cut off).
thanks, governor, for pointing me to this web site, it is packed full of 'put you to sleep reports'. [8D]
