Agnes Christine Gundersen, Einar Hjørleifsson and Helle Siegstad (836.7Kb)

Greenland halibut in the waters of East Greenland, Iceland and

Faroe Islands

Strategies for Commercial Marine Species in Northern Ecosystems

10th Norwegian-Russian Symposium Bergen, Norway, 27-29 August 2003

Agnes Christine Gundersen Einar Hjørleifsson

Helle Siegstad

West-Nordic Greenland halibut

• 1976: ICES defined the Greenland halibut in these waters as one stock.

• "... based on a strong probability that the spawning grounds [for Greenland halibut in these waters] are the

same“.

Distribution

ICES XIV b, ICES Va, ICES Vb

Tagging experiments

for migratory studies

Greenlandic tagging

experimetns

Icelandic taggings and recaptures

28° 24° 20° 16° 12° 8°

62°

64°

66°

68°

Grálúða

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0 10 20 30 40 50 60 70

1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001

Year Landings from areas (1 000 t)

0 10 20 30 40 50 60 70

Total landings (1 000 t)

Va * Vb* XIVb* Total

Trends in landings

Based on ICES 2003

Exploitation of the stock

Va, Icelendic waters

• Catches mainly taken at the

western corner of the Icelandic EEC

• Fishery:

500 – 1 000m depth

• Trawl

0 10 000 20 000 30 000 40 000 50 000 60 000 70 000

1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001

Year

Landings (t)

Iceland*

Others

Faroe Islands

Based on ICES 2003

•Reduction due to reduced TAC by the Icelandic fleet

Vb, Faroe Islands

Main fishing grounds are located east and west of the Islands.

Relatively new fishery Moved from east to west in 2000

Fishing depth:

400-700m

Apart fr Faroe Islands:

1980-ies: Majority taken by France (< 800 t) 1990-ies: Majority taken by Norway (< 250 t)

0 1000 2000 3000 4000 5000 6000 7000

1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001

Landings (t) Others

Faroe Islands * Norway

Germany France

Based on ICES 2003

XIVb, East Greenland

Main fishing grounds along the slope 63 N - 65°N and around 62 °N Depth: 800-1 500m

Relatively new fishery Increase in 1990ies:

increased fishing activity

Agreements:

-Greenland-Norway -Europe

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001

Landings (t)

Germany Others

UK (Engl. and Wales)

Norway Greenland

Based on ICES 2003

Assessment

• Traditionally VPA and XSA

• Since 2000 XSA has been discarded by ACFM

– Poor diagnostics

– Poor and variable input data

– Lack of input some years / some areas – No pattern in incoming year-classes – Ageing problems

– Inconsistent maturity data

– Lack in general biological knowledge

• e.g. maturation, spawning frequency, spawning area(s), recruitment

At present: ASPIC (BETA vers. 4.45)…

• Requirements:

– series of catch data

– indices of stock biomass, either corresponding effort, CPUE, or survey catch rates.

see report of the Northwestern Working Group 2003 (ICES 2003).

• Used:

– Icelandic CPUE series (1985 onwards)

– Icelandic groundfish survey (1996 onwards)

Management

• Suggested: F~F

= 2/3 * F

~ 20 000 t

• No management objective for the stock

• At present: no common agreements in how to share TAC between coastal nations

=> TAC is more like quota in each sub-area…

Leading to overfishing TAC each year

ASPIC 2003

• MSY ~ 35 000 t

• Bmsy ~ 114 000 t.

Total biomass 2003 22% below Bmsy,

F 2002 ~ 10% above Fmsy.

Biomass was at a record low in 1998.

Increased by about 25% till 2003.

Before 1998: F occasionally 60% above Fmsy.

Since 1998: F at the level close to or above Fmsy.

Medium term projections

• F~ F

(20 000 tons)

– biomass is likely to increase.

– The probability of reaching B

by 2005 is 50%.

• F ~ F

(33 000 tons) a risk that the – stock will remain low or

– even collapse

Improving management

Provide input data (stablility from one year to the next).

-Length compositions from fishing fleet

Norwegian fishery in Greenland waters: length

measurements is a part of the licens for operating in the waters. Provides us with consistent length data every year from all vessels.

-Sex composition

-Maturity data, spawning behaviour, peak spawning -Age

Maturity

• Visual determinations are inconsistent

• Lack maturity data in several years

• Problem: estimating Spawning Stock Biomass

• Recently focus has been on this issue – Maturation, atresia, egg production

– Still need ”calibrated” personnel when it comes to maturity determinations.

Spawning entities?

-West of Iceland

(Magnusson, 1977)

(Sigurdsson and Magnusson, 1980)

-East Greenland

(Gundersen et al. 2002)

-Faroe Islands

Observed late maturing females in gillnet catches

Need further information on extent and timing

Stock’s potential egg production

0 1 2 3 4 5 6 7 8 9 10

5 6 7 8 9 10 11 12 13 14 15

Age

TEP (10^10)

1997(1997-98) 1998(1997-98)

1999(1997-98) 2000(1997-98)

HIGH

production scenario

Based on

* fecundity – length for the respective years

*re-estimated spawning stock size

* Age-length- relationships Ages mainly

contributing to egg production

0 500 1000 1500 2000 2500 3000 3500 4000

0 1 2 3 4 5 6 7 8 9 10 11 12

Month

LC oocyte diameter (my) 1 Primary

2 Cortical alveoli 3 Early vitellogenesis 4 Vitellogenesis 5 Vitellogenesis

6 Vitellogenesis, fusion 7 Spawning

8 Spent

Optimal sampling time for maturity ?

Illustration from the Barents Sea

…the end…

Thank You for Your attention