I. Welcome--Tom Jagielo, WDFW
II Workshop Objectives
Topics
III Review Agenda
Methot: Check on logbook data, bring that forward in our discussion
Jagielo: While we do not have a formal presentation, we have some data print outs from David Sampson, OSU--effective effort for OR/WA trawl vessels. We also have maps of OR/WA logbook data, to be used mainly while discussing aspects of catch distribution and stock structure.
IV. Stock Structure
A. Tagging Data
Methot: Any tagging data from Puget Sound?
Jagielo: Yes, Mark LaRiviere published results from tagging in the San Juan Island area; some tagged fish moved out of the straits.
Adams: Did you observe any trends with respect to short term recovery vs long term recovery?
Jagielo: Movement was substantive even after short period of release
Zimmermann: Seems like a very high recovery rate.
Leaman: Were most recoveries obtained in the 1st year?
Jagielo: Yes, however recoveries continued to be observed for 4-5 years giving a nice decay pattern for survival estimation.
Carlile: What is primary recovery gear? Offshore, trawl; nearshore, recreational.
Leaman: Were fish vulnerable to the sport fishery tagged?--these fish are typically smaller .
Jagielo: Yes, the results were published in Jagielo (1995).
Methot: of the 3,000+ recoveries, how many were outside of N. WA area? Jagielo: over 100 fish were recovered from Canadian waters.
Barss: ODFW did a study (with fewer releases) in the late 70's, little movement was observed from the release area.
Adams: one lingcod tagged off CA went to Depot Bay.
Methot: Seems to be the model of movement, some individuals have higher propensity to move, usually in short period of time.
B. Genetics
LeClair: Two loci were clearly different between Puget Sound and coastal samples. The pre-study pilot showed striking differences for 15 fish samples, but the differences were not so striking after larger fish samples were examined.
Jagielo: The literature indicate that it is hard to show sub-population differences for marine fish in general.
C. Fishery Logbook Data
Douglas: what is the block that is way out? Seems like an error.
Hastie: comparing graphs 89 to 95 it doesn’t jump out at you that the overall CPUE is a 5th of 95, as indicated in the bar graph on top.
Jagielo: Another approach for using the log book data is the measure of effective effort, as per David Sampson.
Adams: 95 is the first year of 22" size limit.
Leaman: Are logbooks compulsory? Jagielo: Yes.
Methot: Might be interesting to look at vessels targeting lingcod. Most effort is coming from other vessels.
Hastie: Non-target vessels CPUE not representative of lingcod
Leaman: From analysis of Canadian logbooks, we find you have to get very high qualification levels before you see changes in the CPUE pattern.
V. Bruce Leaman: Review of Available Canadian Data
A. Catch/effort
1956-90 catch and effort data, by gear/locality.
56-90 vessel depth locality gear time cell
91-95 catch effort by vessel by depth locality gear by tow
94-95 catch effort by vessel depth gear tow with lat/lon
96 had observers in 96, data are not yet available.
B. Biological data
Commercial--sparse matrix, most fish dressed at sea
Variable by area--most data for Area 3C (77-96)
Length, sex, age by locality depth time
Research
Variable by area--most data for Area 3C (78-85)
Length, sex, age by locality depth time
C. Tagging--some
77-83 data from /Al Cass., tagging occurred off southwest Vancouver Island, movement occurred to the N and S. Predominately retention in area of release.
Also, tagging study in the Strait of Georgia; showed a little more movement to the south. Not much indication of inside waters to outside waters movement.
D. Surveys--none
E. Assessments
-3C, had some age reading difficulties for post 1986 samples; were aging fish a year younger than should have been, this has now been sorted out.
--small sample size, 50-1200., 1-8 samples.
Estimates of available yields: 3C 95, 1400-2800, NWVI, 400-800, QCS 1100-2200, Hecate Strait/QCIs., 1000 (low/high risk), High risk on catches associated with some change in CPUE., estimates look at total CAN/US catch for area 3C.
Trends in 3C CPUE are highly variable, somewhat cyclic.
Age frequencies 3C(Big Bank): 1985 cohort dominated fishery for about 8 years, trawl fishery, predominately female, no obvious loss of the older age classes 10-11.
VI. Review of available data--Northern Area: Tom Jagielo
A. Biological Data
length at age
Schedules developed for past assessment
In 1994 assessment, the growth curve under-predicted size at age observed for younger fishes (possibly because the sample data represent the fastest growing members of the population) -- A discussion followed on the question of whether the growth function should model the "true" population growth or the observed fishery size at age:
Methot--concerned that size at age 1 was previously fixed at 30 cm, but 30 cm may better apply to age 1.5, as lingcod appear to grow 10cm /y . This is what created difficulty in fitting size modes of young fish from tagging survey data.
Jagielo: We now routinely age fish from the nearshore WDFW survey, so we no longer will have to rely on the length data to interpret age. One approach is to produce an age-length key outside of synthesis, and then model the survey data as age compositions in the age-based model.
Methot: The length-based Stock Synthesis model does the age error transition, in addition to converting size to age.
Jagielo: In 1995, we have the first year of ages from the trawl survey.
Hastie: With respect to observations for 2-3yr olds, do these come from the sport fishery? Because there is a bias for selecting larger fish in the sport fishery.
Jagielo: Yes, size selective discard by the sport fishery was quite evident when analyzing the tagging data. This was discussed in Jagielo(1995). Observations of 2-3 year olds are also available from both WDFW and NMFS survey data.
Tagart: Tom used the age based Stock Synthesis model for the 1994 assessment. This approach would not allow identification of the fastest growing members of the age class as the fraction selected by the fishery.
Methot: Recommend using an approach that converts size to age best; you need separate weight at age vectors for the population and the fishery.
Mean Size at Age
Figures show a marked change in the mean size at age over time, particularly among young fish.
Methot: possible explanation is retaining more small fish in recent years, i.e., size selectivity has shifted.
Jagielo: We are now in the process of re-aging structures from the mid-80s. to see if age reading changes over time are involved.
Discussion: Need to look at time series of selectivity, check fishermen to determine if sorting at sea. Look at the size distribution of the landed catch for more fish on the left hand tail of the distribution, is there evidence for increasing numbers of small fish in the landed catch over time?
Methot: keep in mind the increase in mesh size -- regulation in place in 94, transition to regulation began in 93.
O’Connell: has CARE traded lingcod structures? ANS: Not reported to date.
Methot: if fishery selection changed over time, could be an argument to move to a size based model. Size based Stock Synthesis still uses all the age data, and gives you the flexibility to fit changes in size selectivity.
maturity at age
length-weight
natural mortality
B. Fishery Data
Catch trends by INPFC area:
Coastal trend: little catch in Conception area , increases in Monterey, low in Eureka, High in Columbia/US Vancouver, highest in Canadian Vancouver, Charlotte areas. (Source PacFIN)
WA sport catch: Peaked in 93, drops in 95,96. -- Culver: notes the 22" size limit may have contributed to drop in total catch.
Adams: OR sport fishery -- MRFSS data, 81-89, 93-present, OR portion of COL, 200-300 t, about a 1/3 of the commercial catch.
Age composition
Displayed raw frequency distribution (79-96)--we see a strong 84 year class (Leaman had shown a good 85 year class for Canada), also good 78, 79 year classes.
Methot: Looking at these data, you do not see any change in the proportion of 4 year olds over time.
Zimmermann: was there a reduction in size at age as the strong year classes moved through the fishery?
Jagielo: comparison of the 1984 and 1978 year classes (figure) are the only comparisons run to date.
Sports gear age compositions: fewer years of data (86-95)
Fishery Logbook CPUE--
Jagielo: Plan to start over with this data, will not use approach taken with logbook data in 1994 assessment. However, the logbook data clearly need to be addressed. Plan to focus on examination of the OR/WA effective effort data set provided by David Sampson.
Culver/Methot: What assumptions has David Sampson used to get effective CPUE? This needs to be addressed.
Discussion: about the appropriate use of Sampson’s data, do assumptions seem reasonable, then how does it behave with other data when modeled.
C. Survey Data -- Mark Zimmermann
Survey Description
Trawl poly noreastern, 3.2 cm cod end mesh, 14" bobbins, mean width 13 m, 8m high.
Two vessels per year, chartered, fishing alternate track lines working south to north.
Stations assigned ahead of time, skipper determines if site fishable.
Scanmar net mensuration for real time data on net configuration, sat nav.
Bottom contact sensor, bathythermograph data are used to help class trawls as good or not
Bad hauls removed from data analysis, e.g. when gear fails to tend bottom, or when gear is ripped.
E-W track lines, min one trawl per depth strata, track lines systematic, stations along track lines random. (Fixed stations, not re-sampled annually)
Catches <1000kg whole haul sampled, larger catches are sub-sampled, 200-300 fish (important spp) lengths and sub-sample for age.
4 depth zones, 14 lat areas, 4 unfishable zones (off CA, Monterey)
Results
1977 is the highest biomass estimate, catch can be dominated by few large surveys. Lingcod caught in 20% of hauls in 77, not much data collected in 77, lingcod were not a target spp, caught less than 1000 lingcod in 77
Leaman: Thompson’s book on adaptive sampling. Should be looked at, but when you look at the "mother of all surveys" have to condition yourself to what you expect to get out of it.
1980 - moved southern boundary, moved further inshore 91-55 m., fished into Canada., added some high density trackline strata. (Doubled density). Two large catches (accounted for 35% of all fish caught), 30% of the hauls.
1983 similar to 1980. Caught lingcod in ~50% of the trawls, yet biomass estimate declined.
1986 stratified again, added stations in Vancouver area, 3A, central OR., south OR skipped due to bad weather. Lower biomass estimate (20% of 77) no monster catches
1989 re-stratified again, multi-species focus on hake, then rockfish. Down to two depth zones, some rebound in biomass. 3 100 kg catches, two off Van area. Took lengths on half the fish, caught ~1700 fish.
Displayed cumulative plot of catch by depth by size group; smaller fishes caught in <100 m , >50cm fish in 100-200 m.
Displayed cumulative plot of catch by latitude by size group; smaller fish south of 38 degrees, most (80%) of larger fish, north of 46 deg.
1992 stratification same as 89, lingcod in 40% of the hauls, measured 75% of fish caught, biomass very low.
Cumulative plots not as distinctive as in 89
Displayed catch by bottom temp by size group, medium and small fish separated by temp, small in warmer water.
Cumulative plot by latitude, very different than seen in 89, all fish caught in north
1995 survey stratification changed again., lowest biomass for all years, Farallon Islands large catches, desert until WA., no large catches (none > 62 kg/ha), measured more of the fish, took age structures as well.
Cumulative catch vs depth, not much separation among small size groups, more separation for large size
Cumulative vs temp, juveniles still in warm water 8.5-9.0, mid size, 7.5-8.0, adult 7-8.0 (<30 cm, 30-50cm, >50cm).
Cumulative vs latitude, juveniles off CA <38deg account for 80% of small fish,
Catch per haul, typically <4 fish.
Discussion: Trawl survey abundance estimates: could we look at a different abundance estimator, test residuals against alternative estimators? An extended discussion followed of alternative estimators, winsorized data, log transformed data, etc.-- all adjustments could bias abundance estimate., but may lower variability. Question of attention to the original sample design.-- Hastie, most vocal advocate of using transformed data, accepting the induced bias, and evaluating models against the alternative trends.
Jagielo: Displayed trend in point estimates of abundance from trawl survey, and age frequency data from >95 survey.
WDFW Surveys: Tagging nearshore 86-93, offshore 91-93; length frequency (86-93) Nearshore estimates of abundance (N), fishing mortality (F) and net loss (L) of tagged fish. Results published in Jagielo (1995). Size distribution data from nearshore survey.
D. PFMC 1994 Stock Assessment results:
Stable biomass, but exploitation > F35% for many years., Natural mortality assumed constant M=.32 males, .18 for females, from Hoenig’s method. Did not profile on M.
Methot: Lack of fit to nearshore size data will hinder models opportunity to fit the 1984 year class data presented in the size. Need to look at variability of size at age. Tweak variability allowed for growth parameters, using the size based model, to make more distinct size modes at a given age.
Jagielo: Nearshore tagging estimates of survival and fishing mortality implied that these values of M were not implausible.
VII. Review available data--Southern area: Pete Adams
Began sampling in 1992. Sampling density higher in 92-93 and dropped off since then.
Commercial fishery--most of the sampling in COL area, 9-35 samples/y 266-1200 fish.
Eureka south 9-22 samples, 200-600 fish.
Sport fishery samples: CDFG party boat fishery--goes from Eureka to Morro Bay, started in 1993, 500-600 fish 92, 93, now down to 200 fish.
Columbia area analysis of the impact of the 22" size limit (imposed Jan >95) – have not observed as dramatic a drop in size composition as might have been expected.
O’Connell: Do you see a different distribution of young females from young males?
Jagielo: Nearshore surveys show a 5:1 male/female ratio in Washington.
In Conception area 1/3 fish commercial, 2/3 sport.
Validation of age technique, age one fish 308 mm @ 365 d (based on daily growth increments). OTC injected fish, recovered 11, one was mis-aged. 3 fish more than 1 y at liberty. Error off by 2 years.
Maturity -- macroscopically determined, 548mm L50.
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March 21, 1997
Convene 8:00 AM
VIII. PFMC 1997 Lingcod Stock Assessment
A. Operational Stock(s) to be Assessed
Jagielo: The 1994 assessment treated Cape Falcon to 49 degrees North in Canada as a unit. At this time, I propose to assess the Canadian Vancouver through Columbia areas as a unit.
Leaman: Not convinced that the US and Canadian portions of 3C are behaving the same way.
Jagielo: We clearly need resolution of aging differences; for example, why was the strong year class read as 85 in Canada vs 84 in US? From a fish management perspective, it is clear that the fisheries are prosecuted differently by area, but that can be modeled in Stock Synthesis. As in the 1994 PFMC assessment, we will model the Canadian trawl fishery as a discrete fishery. The question from an assessment perspective is, for what spatial units do we determine biomass estimates?
Leaman: My point was to treat the US and Canadian fisheries separately within the analysis.
Hastie: Different age structures in the US and Canadian fisheries could lead to inappropriate ABC.
Jagielo: Age compositions are not so different in The US Vancouver vs Canadian Vancouver. Based on the 1995 NMFS survey age composition data, the real differences show up when you compare the northern (Vancouver/Columbia) with the southern (Eureka/Monterey/Conception) INPFC areas.
Leaman: Several items of evidence suggest that the US/Canadian aggregations ought not to be treated as a common stock. Differences in survey stock abundance, age composition differences, small amounts of tag movement (at least from the Canadian releases), lack of fit to Canadian data in the previous model.
Tagart: Seems unequivocal that fish move back and forth across the boarder.
Leaman: There may be some movement but whether it is the case that the imposed fishery mortality in each area affects the other area is uncertain. Evidence not convincing that we should treat the US and Canada as a single stock.
Jagielo: The previous assessment modeled the BC and US commercial fisheries and the US sport fishery independently. Each fishery having a separate fishery selectivity.
Leaman: If we apply a different management regime in Canada than the US, the question is will each country’s regime affect the others fishery? I want to share data, but I am just not convinced that this represents a common stock.
Tagart: I don’t think that population dynamics will provide an indication of whether or not the US and Canadian stocks are common or separate. I believe we can only resolve this question by joint tagging, simultaneous releases in each year. If we can’t find that US and Canada should be treated as a single stock, there is little justification to treat the US fishery as a single stock, because the prima facia evidence is largely the same as that for combining US and Canada.
Jagielo: I can’t reasonably ignore the catch on the Canadian side of the boarder which is occurring in such close proximity to the US fishery.
Leaman: The issue is how much effect does the fishery in one area have on the fishery in the other. If we don’t expect to manage these as separate stocks, maybe we should lump the data into one large stock unit. It is a reality that we do have separate management regimes in US and Canada. The weight of evidence now suggests net emigration to Canada.
Jagielo: I don’t think that is the case, because we don’t have the releases in Canada to compare with the US.
Hastie: maybe we need to model both ways , i.e., no mixing with Canada, versus mixing with Canada.
Jagielo: What I hear is that there is a desire to do a collective (US/Canada) assessment, but that it is unresolved if we have separate stocks. Should we recommend to TSC an age structure exchange between US/ Canada? ANS: yes.
Tagart: There seems to be some evidence to split US fishery into at least 3 stocks, Eureka South, S. Columbia and N. Columbia/US-Vancouver. Splitting the Columbia somewhere just north of Yaquina.
Hoffmann: Seems to me we don’t know where to draw these lines, so we need to ask what is the worst case : splitting when we shouldn’t, or lumping when we shouldn’t?
Jagielo: Too many splits begin to load the analysis with too much to do.
Hastie: The pooled Columbia area does have more survey age data to use in the analysis, combined with the 5 years of fishery data, this may be sufficient for analysis.
Barss: The 4,000 fish tagged off of Stonewall Bank didn’t show any significant northward movement, so it seems Oregon should be treated separately.
Hoffmann: the management concern should be what drives the question of whether to lump or split areas.
Group Summary recommendations:
Model from Canadian Vancouver through Columbia as a unit. For US/Canada comparisons, model Canadian Vancouver and US Vancouver independently, and compare with a model of the entire Vancouver area as a unit. Analysts will look at all data sets for evidence of independent stocks within the Canadian Vancouver through Columbia unit, but lacking compelling evidence will treat as a single stock. First priority: analyze Canadian Vancouver through Columbia as a unit. Second priority: model a US/Canada split of the Vancouver area. Third priority: analyze the entire Vancouver area as a unit. (The US/Canada model comparisons might be deferred to the off-cycle period.)
B. Model Approaches
C. Other Assessment Tools - Particularly for southern area where data for a traditional age structured assessment are lacking:
Adjourn: 11:30 AM.