Sex-biased movement of Atlantic halibut on Scotian Shelf and - - PowerPoint PPT Presentation

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sex biased movement of atlantic halibut on scotian shelf
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Sex-biased movement of Atlantic halibut on Scotian Shelf and - - PowerPoint PPT Presentation

Dec 09, 2023 527 likes •847 views

Sex-biased movement of Atlantic halibut on Scotian Shelf and southern Grand Banks but first, why we are interested in that Nell den Heyer , K. Ransier and N.L. Shackell Fisheries and Oceans, Canada IFS Nov 2017 1 Large, long-lived

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Sex-biased movement of Atlantic halibut on Scotian Shelf and southern Grand Banks

…but first, why we are interested in that…

Nell den Heyer, K. Ransier and N.L. Shackell Fisheries and Oceans, Canada IFS Nov 2017

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Large, long-lived and sexually dimorphic

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Age (years) 50 40 30 20 10 250 200 150 100 50

Males

Both gears Linf = 132 K = 0.20 T0 = 1.1 R2 = 0.49 n = 892 Age (years) 40 30 20 10 250 200 150 100 50 Both gears Linf = 206 K = 0.10 T0 = 0.12 R2 = 0.69 n = 1343

Females

From Armsworthy and Campana 2010

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3L 5Y

Newfoundland Overseas France

Managed as two separate stocks: Gulf of Saint Lawrence Scotian Shelf & Southern Grand Banks (Newfoundland)

Both are experiencing a period of high juvenile recruitment3

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1970 1976 1982 1988 1994 2000 2006 2012 5 10 15 20 25 30

Total Legal Spawning

Year

Biomass, 1000t

2015 Value of Commercial Groundfish Atlantic Canada = $216 Million

Greenland halibut Atlantic halibut Haddock Atlantic Cod Redfish spp. Flatfishes Other

2015 Value of Commercial Groundfish Canada = $362 Million

Greenland halibut Atantic halibut Pacific halibut Flatfishes Redfish spp. Haddock Cod Other

Halibut survey biomass index

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Canadian and foreign landings

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Some of this is Greenland halibut

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FISHING HISTORY

  • <1700’s-early 1800’s

Halibut=NUISANCE in US Cod fishery (not easy to salt)

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http://www.photolib.noaa.gov/700s/figb0010.jpg

Commercial

fresh fish on ice

1836L overfished By 1850 L overfished

…not so heavily fished

1880= L Collapse

  • Head to Canada

under Treaty of Paris (1783) By 1850 L overfished US fishermen predominate. Canadians not in until 1900s Train system improves in early 1800s providing easier access to Ice

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Atlantic Halibut Research History

50s and 60s: tagging 80s: maturity, tagging, yield model è management units, TAC and min size 1998 –present: Industry-DFO halibut longline survey 2003-2007: growth and age-length key 2006-present: conventional tagging 2007,2009,2011&12: PSAT tagging 2010: first age-structured length based assessment model 2014: new assessment framework with MSE approach 2015-present: Spatial ecology 2017-present: Genetics 2017: New Stratified Random Survey

from Trumble et al. 1993

Pacific Halibut

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(Nancy Shackell, Nell den Heyer, Kiyomi French/DFO, Canada) Connectivity Current=2000km; Estimated=250km Partial Migration of Mature female R residents: 29 km

Winter Migration: <200km

Size of Juvenile Habitat ~ Adult landings

Q: Are the following consistent with current stock unit domain?

Life history trait A: No… how can this contribute to sustaining stock?

  • add Spatial Management to Framework Assessment

? Range expansion/secondary role of closed areas Genetic landscape (in progress) MSE by spatial units

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Halibut all-sizes tagging - “pink”

Ø Estimate natural and fishing mortality Ø Describe movement and distribution

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Counter current migration

  • H1. Juveniles moving farther than adults and from west

to east.

(larval drift to the west) 10

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Sex-biased seasonal movement

H2 Movement varies by sex and season

Mature males: 80cm+ Mature females: 103cm+ (4X), 119cm+(3NOPS4VW) Summer: April to August Winter: September to March

Residents: less than 20 km Migrants: 20km to 250 km Nomads: 250 km+

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Halibut all-sizes tagging

§ Over 4500 halibut tagged since 2006 § Double tagged to estimate tag loss § During halibut longline survey in May-July § Tag allocation by NAFO area proportional to abundance § All sizes – fishermen compensated for release of legal fish § Rewards for returns – AHC $100 reward per fish (with one or

two tags) plus chance to be chosen in a quarterly draw for $1000

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N=4559

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n=811 n male = 261 n female = 302 n=4559 n=811 n male = 261 n female = 302

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Residents Migrants Nomads Year <20km 20km-250km >250km 48 46 3 1 128 99 33 2 74 76 20 3 46 33 17 4 21 28 16 5 13 19 10 6 12 12 7 7 6 19 4 8 6 3 5 9 1 3 10 2 1 Total 356 337 118 Percent 44% 42% 15%

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ü For juveniles no difference by sex or season ü Mature females different in winter and summer ü Mature males different from mature females in summer and mature females in winter ü Mature males not different from juveniles

Summer Winter Immature

  • Mature
  • Net distance moved by season, sex and maturity

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Immature males and females and mature males

Mean squared displacement, km2 Time between release and recapture, by quarter Year 1 Year 2 Year 3 Year 4

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Counter current ‘migration’

Juveniles (and mature males) move further than mature females in summer and largest movements biased to east and west

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Residents Migrants Nomads <20km 20km-250km >250km n Summer Immature_Female 50% 35% 14% 105 Immature_Male 43% 45% 12% 75 Mature_Female 71% 24% 4% 91 Mature_Male 58% 29% 13% 38 Overall 56% 34% 11% 309 Winter Immature_Female 39% 44% 17% 71 Immature_Male 28% 48% 24% 93 Mature_Female 29% 49% 23% 35 Mature_Male 35% 47% 18% 55 Overall 33% 47% 20% 254

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Median = 5.9 km, mean= 42km

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Median =80 km, mean= 125 km

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§14 successful deployments §Stars indicate deployments with spawning rises

From Armsworthy et al. 2014

Pop-up satellite archival transmission (PSAT) tags

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Counter current migration

Juveniles (and males) move further than mature females in summer and largest movements biased to east and west

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? ? ? ?

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ØHigh proportion of halibut are resident, with some being caught up to

10 years after release within 20km of release

ØLarge females are more likely to be recaptured within 20km of release

in the summer, suggesting established summer foraging areas

ØIn winter, large females more likely to move than all other halibut ØSouthern Grand Banks and Gully are potential areas for spawning ØJuveniles are more likely to move the greatest distances ØMovement of juveniles and adult males are consistent with diffusion ØLargest movements along the coast are predominantly from east to

west

Conclusions

Area-based management, MPA design, spawning stock structure, as well interpretation/application of deployment of satellite tags on large halibut

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Acknowledgements

§ Eastern Shore Fisherman's Protective Association § Shelburne County Quota Group § Atlantic Halibut Council § Javitech § K. Trzcinski, S. Armsworthy, G. Wilson, S. Wilson, L. Bajona,

  • M. McMahon, B. Wringe, S. Smith

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a) non-breeding partial migration b) Breeding partial migration c) Skipped breeding partial migration

Chapman et al. 2011

Partial migration

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Release Recovery (%) n 0B 3N 3O 3P 4Vn 4Vs 4W 4X 5Y Males 3N 14 29 64 7 3O 13 8 62 15 8 8 3P 46 13 67 2 9 4 4 4Vn 8 88 13 4Vs 33 9 70 21 4W 43 14 14 63 9 4X 28 4 7 29 61 Females 3N 56 29 66 5 3O 26 4 73 19 4 3P 53 2 2 85 9 2 4Vn 3 33 67 4Vs 38 11 68 21 4W 28 14 7 14 61 4 4X 29 7 10 7 14 55 7

Percent of those recaptured in NAFO area, by area of release

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Adapted from http://www.iiasa.ac.at/web/scientificUpdate/2013/researchProgram/EvolutionandEcology/EvolutionaryConsumption.html

Unit Stock

…all of this affects all of that->

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