Stock Assessment Of Nafo Subdivision 3ps Cod-Books Pdf

Stock Assessment of NAFO Subdivision 3Ps Cod
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Newfoundland and Labrador Region Stock Assessment of 3Ps Cod. This Science Advisory Report is from the October 16 17 2018 Assessment of NAFO Subdivision 3Ps. Atlantic Cod Additional publications from this meeting will be posted on the Fisheries and Oceans. Canada DFO Science Advisory Schedule as they become available. Consistent with recent assessments a cohort model SURBA based on the spring DFO. survey was used to infer overall stock trends, The 2018 Spawning Stock Biomass SSB is estimated to be in the Cautious Zone 49. above Blim as defined by the DFO Precautionary Approach PA Framework The probability. that the stock is in the critical zone is 0 04, SSB has increased since 2015 In 2018 71 of the SSB is comprised of ages 6 and 7. Recruitment has generally been at or above the time series average since 2005 with a. particularly strong cohort produced in 2011, Estimated total mortality remains high Over 2015 17 total mortality averaged 0 61 54. survival per year however the relative contributions of natural and fishing mortality to total. mortality are unknown, Projection of the stock to 2021 was conducted assuming total mortality rates will be within. 20 of current values 2015 to 2017 average All projections show SSB in 2021 to be. lower than SSB in 2018 Where total mortality is assumed to remain at or above current. levels projections indicate that SSB in 2020 and 2021 to be at or below Blim. The ecosystem in Subdivision 3Ps remains under reduced productivity conditions Spring. bloom magnitude and zooplankton biomass have shown very low levels since 2014 which. would negatively impact transfer of energy to higher trophic levels However there are some. improvements in biological indicators for cod in 2018 e g condition and diet. INTRODUCTION,Oceanography and Ecosystem Overview, Oceanographic conditions in Subdivision 3Ps are influenced by several factors including local.
atmospheric climate conditions advection by the Labrador Current from the east and the. warmer and saltier Gulf Stream waters from the south as well as the complex bottom. topography in the region Near bottom temperatures while showing significant variability from. one year to the next have experienced a general warming trend up to 1 5 C in some areas. since 1990, Satellite remote sensing data indicate that the spring bloom in 3Ps was lower in intensity and. magnitude during 2015 18 but the timing of peak magnitude and duration were near normal in. 2018 The biomass of both small and large size fractions of zooplankton in 3Ps continue to. remain near the lowest levels observed in the 19 year time series Reductions in standing. stocks of phytoplankton and zooplankton observed in recent years indicate changes in the. structure of the ecosystem and lower productivity conditions that may influence higher trophic. The overall biomass of the fish community in 3Ps has been relatively stable since the. mid 1990s but there were clear internal changes in the fish community with signals of reduced. productivity in the 2010s Ongoing warming trends together with an increased dominance of. warm water species and reduced fish sizes across many fish functional groups indicate that this. Newfoundland and Labrador Region Stock Assessment of 3Ps Cod. ecosystem is undergoing structural changes Although there are some positive indicators for. cod e g improvement in biomass and more fish in the diet these signals are not widespread. nor fully consistent across the fish community The ecosystem still remains under reduced. productivity conditions,History of the Fishery, The stock was heavily exploited in the 1960s and early 1970s by non Canadian fleets mainly. from Spain with catches peaking at 87 000 t in 1961 Fig 2. After the extension of jurisdiction in 1977 landings increased to peak at almost 59 000 t in 1987. due to increased landings by France Landings then decreased sharply to about 40 000 t during. 1988 91 before decreasing further to 36 000 t in 1992. A moratorium was imposed in August 1993 and at that time 15 000 t of the 20 000 TAC had. been landed Although offshore landings fluctuated the inshore fixed gear fishery reported. landings around 20 000 t each year until the moratorium. The fishery reopened in May 1997 with a TAC of 10 000 t increasing to 30 000 t by 1999 In. 2000 the management year was changed to begin on 1 April Total Allowable Catches and. landings over the past decade are shown in Table 1 and are described in detail below The TAC. was set at 6 500 t for the 2017 18 management year and at 5 980 t for the 2018 19. management year, Figure 2 Reported annual landings and TACs t from 1959 2018 Values are based on calendar year. from 1959 2000 and on management year 1 April 31 March since then Landings for 2018 2018 19. season are incomplete and not displayed, Newfoundland and Labrador Region Stock Assessment of 3Ps Cod. Table 1 TAC and landings by management year thousand metric tons. Management, 09 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 191 2.
TAC3 11 5 11 5 11 5 11 5 11 5 13 225 13 49 13 043 6 5 5 98. Canada 7 5 6 6 5 2 4 0 4 6 5 8 5 9 5 2 4 9 2 3,France 1 5 1 3 1 1 0 8 1 4 1 6 0 9 1 1 0 2. Totals 9 0 7 8 6 3 4 8 6 0 7 3 6 8 6 3 5 0 2 3,Provisional. Approximate landings to 5 October 2018, TAC is shared between Canada 84 4 and France St Pierre et Miquelon 15 6. Reported combined landings by Canada and France were substantially below the TAC from the. 2009 10 season to 2016 17 but during the 2017 18 season approximately three quarters. 77 of the 6 500 t TAC was landed Prior to 2009 10 the TAC had been almost fully. subscribed with the exception of the initial four years of TAC regulation Industry participants. have indicated multiple reasons contributing to the recent reduction in landings including. reduced cod availability and economic factors Of the 5 031 t landed during the 2017 18 season. 4 862 t was taken by Canada including 13 t from sentinel surveys and 169 t was landed by. Provisional data indicate that landings during the ongoing 2018 19 management year were. 2 252 t as of 5 October 2018 Although incomplete these landings to date are comparable to. those during the same period in 2017 18 when a slightly higher TAC of 6 500 t was not taken. During the 2017 18 season more than three quarters of the total landings were taken by fixed. gears dominated by gillnet with the remainder taken by the otter trawl fleet. Species Biology, Stock structure and migration patterns of 3Ps cod are complex Cod in 3Ps mix with adjacent. stocks at the margins of the stock boundary Some offshore components of the stock migrate. seasonally to inshore areas and there are inshore components that are shoreward of the spring. DFO Research Vessel RV trawl survey area These features add uncertainty to the. assessment of stock status However since 1994 additional information has been obtained. from various sources including tagging acoustic telemetry and the sentinel fishery This. information has provided a basis for several measures to investigate the potential impact of. these factors i e stock structure and migration patterns on the assessment Survey timing. was shifted to April beginning in 1993 and winter fishery closures in some areas have been. imposed to reduce the potential for migrant non 3Ps cod being sampled by surveys and. included in commercial catches The spring DFO RV trawl survey covers most of the stock so. survey trends are thought to broadly reflect stock trends. Spawning is spatially widespread in 3Ps occurring close to shore as well as on Burgeo Bank. St Pierre Bank and in the Halibut Channel Timing of spawning is variable and extremely. protracted with spawning fish present from March until August in Placentia Bay Detailed. examination of fish collected from Halibut Channel southern portion of 3Ps in March and April. of 2015 and 2016 suggested that spawning in this area began in April Also it was noted that for. these fish all females initially categorized as spent were in fact likely skipping spawning. therefore previous estimates of spawning time may be biased and estimated to be earlier than. actual spawning times, Maturation in female cod was estimated by cohort The proportion of female cod maturing at.
ages 4 6 is higher for all cohorts subsequent to the 1985 cohort The reasons for the change. Newfoundland and Labrador Region Stock Assessment of 3Ps Cod. toward earlier age at maturity are not fully understood but may have a genetic component that is. partly a response to high levels of mortality including fishing Males generally mature about one. year younger than females but show a similar trend over time. Growth calculated from length at age in research trawl survey samples has varied over time. For cod older than age 3 there was a general decline in length at age from the early 1980s to. the mid 1990s For most ages there was an increase in length at age from the mid 1990s. through the mid 2000s followed by a period of lower length at age in recent years Length at. age during 2013 17 was among the lowest in the time series During 2018 an increase in length. at age was observed for most ages, Condition or condition factor is a measure of fish weight relative to length and is considered a. proxy for energy reserves Comparison of post 1992 condition with that observed during. 1985 92 is difficult because survey timing has changed Condition varies seasonally and tends. to decline during winter and early spring There were signs of improved fish condition during. 2008 13 but condition values for 2014 17 subsequently declined and were among the lowest in. the time series In 2018 condition returned to average values Similarly most estimates of. condition from sentinel sampling increased in 2018. ASSESSMENT,Resource Status,Sources of Information, A cohort model SURBA based on abundance indices from Canadian RV trawl surveys. 1972 2018 is used to infer overall stock trends Cadigan 2010 This model can only use a. single index of stock abundance Although additional sources of information are presented see. Other Data Sources below only the RV survey data was selected as the input data for the. model because it is collected with a standardized design over most of the stock area and is. thought to best reflect overall trends in the stock. Research Vessel Surveys, Canadian DFO RV bottom trawl surveys have been conducted in 3Ps since 1972 however. surveys from 1972 82 had poor coverage The surveyed area was increased by 18 by the. addition of strata closer to shore in 1994 and 1997 The survey was not completed in 2006. Survey indices based on strata 550 m 300 ftm are presented for the expanded DFO survey. area since 1997 inshore plus offshore denoted All index strata as well as for the offshore. only strata Offshore index strata in figures 3 and 4 Any near shore aggregations in April. would not be measured by the DFO RV survey The majority of the area shoreward of the DFO. RV survey lies within inner and western Placentia Bay There is no recent evidence that a large. fraction of the stock is shoreward of the DFO RV survey in April. The biomass index from the offshore strata is variable but exhibits a downward trend from the. mid 1980s to the early 1990s Fig 3 Values for most of the post moratorium period from 1997. to 2004 were higher than those of the early 1990s but not as high as those of the 1980s. Biomass estimates in recent years have generally been low with eight of the last twelve years. being below the 1997 2018 average Survey catches in 2018 were generally low with higher. catches only in strata just to the south of St Pierre and Miquelon Survey biomass from the. expanded index All index strata shows similar trends to the offshore only index. Newfoundland and Labrador Region Stock Assessment of 3Ps Cod. Figure 3 RV survey biomass indices t Error bars are one standard deviation for combined survey. index dashed line is the time series average of the combined survey index. The offshore DFO RV abundance index is variable but values during the 1990s were generally. lower than those from the 1980s Fig 4 Abundance was low during the 2000s but somewhat. higher over 2010 15 with four of the six years being at or above average In particular the 2013. estimate was very high with a high measure of uncertainty In 2018 abundance levels were. below the 1997 2017 average similar to those observed in 2017 and during the 2000s. Figure 4 Research vessel survey abundance indices Error bars are one standard deviation for. combined survey dashed line is average of combined survey index. Age Composition, Catches during the 2018 RV survey consisted mainly of cod aged 2 6 78 of abundance. index The 2011 age 7 in 2018 and 2012 age 6 in 2018 year classes remain strong The. abundance of cod older than age 7 is relatively low. Newfoundland and Labrador Region Stock Assessment of 3Ps Cod. Reference Points, The Limit Reference Point LRP for this stock is BRecovery the lowest observed spawning stock.
biomass SSB from which there has been a sustained recovery The 1994 value of SSB based. on the SURBA analysis has been identified as the LRP The Upper Stock Reference USR has. been defined by fisheries managers as two times the LRP Mortality reference points have not. been identified for this stock,Spawning Biomass, Cohort analyses of the RV data indicated that SSB declined by 58 over 2004 09 Fig 5. Median SSB was estimated to be just below the LRP in 2009 SSB. Newfoundland and Labrador Region Science Advisory Report 2019 009 February 2019 STOCK ASSESSMENT OF NAFO SUBDIVISION 3P S COD Image Gadus morhua Figure 1 Subdivision 3Ps management area and economic zone around the French islands of St Pierre et Miquelon SPM dashed line

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