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Fisheries Monitoring and Assessment > Mackerel Biology and Fishery > Flashcards

Mackerel Biology and Fishery Flashcards

1
Q

What class does mackerel belong to?

A

Actinopterygii

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2
Q

What order does mackerel belong to?

A

Perciformes

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3
Q

What family does mackerel belong to?

A

Scombridae

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4
Q

What is the scientific name for mackerel?

A

Scomber scombus

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5
Q

Describe the Irish mackerel fishery

A

-Exploited in a directed fishery for human consumption
-Single most important fishery
-Numerous jobs as sea and on coast
-Largest and most economically valuable pelagic stock in NE Atlantic
-Processing industry depends on landings

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6
Q

Where is the main port?

A

Killibegs

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7
Q

Where also is mackerel landed?

A

Norway and UK

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8
Q

What export markets are there for mackerel?

A

Germany, Russia, Egypt and Africa

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9
Q

What ways are mackerel sold?

A

-Fresh
-Frozen
-Smoked
-Canned

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10
Q

What ways are mackerel sold?

A

-Fresh
-Frozen
-Smoked
-Canned

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11
Q

How are mackerel fished?

A

Modern pelagic trawls
Mid water otterboard trawling
Purse Seining

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12
Q

What is the main fishing season for mackerel?

A

October to March

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13
Q

When is the Irish mackerel fished?

A

January / February

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14
Q

What habitats are mackerel caught in?

A

Shelf areas and along the shelf edge

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15
Q

What depths are mackerel caught at?

A

15 - 200 m

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16
Q

What type of fish are mackerel?

A

Pelagic, but can be found anywhere in the water column
-Typically epipelagic

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17
Q

Are mackerel solitary or shaoling?

A

Shoaling, with shoals 9km long, 4km wide and 40m deep

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18
Q

Where are mackerel commonly found?

A

Cold and temperate shelf areas (>6 degrees)

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19
Q

Where are mackerel commonly found?

A

Cold and temperate shelf areas (>6 degrees)

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20
Q

Do mackerel have a swim bladder?

A

No, they must constantly swim or they will sink

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21
Q

Describe mackerel.

A

-Metallic blue-green dorsally
-Fade to silver along sides and belly
-20-30 wavy black bars running down sides
-Atlantic mackerel have tapered body, large head and mouth
-Two large dorsal fins and forked caudal fin

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22
Q

The is the maximum length of mackerel?

A

66cm

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23
Q

What is the average length of mackerel?

A

40-44 cm

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24
Q

What is the max recorded weight?

A

3.3 kg

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25
Q

What is the average weight of mackerel?

A

0.68 kg

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26
Q

How can mackerel age be determined?

A

Otoliths- unreliable after 6-7 years of age
Scales- unreliable

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27
Q

Do juvenile mackerel grow quickly?

A

Yes

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28
Q

What size can mackerel be after 1 year?

A

22 cm

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29
Q

What size can mackerel be after two years?

A

30 cm

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30
Q

What is the minimum landing size of mackerel?

A

30 cm

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31
Q

What is size range of catches?

A

33-35 cm
This can vary with year/location (20-40cm)

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32
Q

What is the age catch range of mackerel?

A

1- 15 years

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33
Q

What is the average catch age for mackerel?

A

4-8 years

34
Q

When are mackerel sexually mature?

A

2-4 years

35
Q

How many female mackerel spawn at two years old?

A

60%

36
Q

What is the NEA?

A

Northeast Atlantic mackerel and is assessed as one stock

37
Q

What are the three spawning components of the NEA mackerel stock?

A

Western Component - 77% of NEA
Southern Component - 19% of NEA
North Sea Component- 4% of NEA

38
Q

What divisions are included in the Western component?

A

VI, VII, VIIIa,b,d,e

39
Q

What divisions make up the southern componenet?

A

VIIIc, IXa

40
Q

What divisions make up the North Sea component?

A

IV, IIIa

41
Q

What is the total distance that mackerel will travel in a year?

A

500 - 1000 nautical miles

42
Q

Do juveniles travel as far north as adults?

A

Tagging has shown that juveniles do not migrate as far north

43
Q

How fast can mackerel swim?

A

5.5 meters / sec and up to 50 nautical miles a day

44
Q

Where are the mackerel feeding areas?

A

June - January
West Scotland- Shetland islands
Norwegian sea
North sea

45
Q

Are mackerel migratory?

A

Highly

46
Q

Where do mackerel overwinter?

A

December to February
North of Scotland

47
Q

Where are mackerel spawning grounds?

A

February - July
South, South west of Ireland

48
Q

Where do mackerel that spawn in southern and western areas migrate to feed?

A

To Nordic seas and North sea during second half of year after spawning

49
Q

What does the path of the migration coincide with?

A

With the location of the relatively warm high saline eastern Atlantic water flowing northeastwards

50
Q

What has been linked with timing of overwintering, spawning migration?

A

Linked with temperature -earlier overwintering and spawning related to increased temperatures

51
Q

Why is it thought that extended migrations to Iceland have been happening?

A

Thought to be due to climate change

52
Q

What depths do mackerel spawn at?

A

Continental shelf, in shallow waters (200m)

53
Q

What temperatures do mackerel spawn at?

A

Between 9 - 10 degrees

54
Q

Describe mackerel early spawners

A

-Winter slopes near spawning area
-March/April
-Larger and older fish

55
Q

Describe mackerel late spawners

A

-Winter further away
-Spawn May/ July
-Smaller and younger fish
-First time spawners

56
Q

What type of spawners are mackerel?

A

-Batch spawners, eggs are laid in batches over a period of time

57
Q

How many batches are laid?

A

20 separate

58
Q

How many eggs can female mackerel lay?

A

400,000 - 500,000
Average 250,000

59
Q

What size is mackerel eggs?

A

1.2 mm

60
Q

How long does it take for mackerel eggs to hatch?

A

5 - 10 days

61
Q

What size are mackerel larvae with yolk sacs?

A

2.5 mm

62
Q

How long does it take for larvae to absorb their egg yolks?

A

9 days

63
Q

What do mackerel feed on?

A

-Plankton
-sand eels
-Sprat
-Norway pout
-Polychaetes
-Zooplankton
-Crustacea

64
Q

What do larvae feed on?

A

Copepods

65
Q

Do mackerel feed during the winter?

A

They stop feeding almost completely during winter

66
Q

Describe pelagic trawlers

A

Up to 100m, operate individually or in pairs

67
Q

How do freezers trawlers operate?

A

Up to 150m and use mid water pelagic nets

68
Q

What does RSW stand for?

A

Refrigerated Sea Water

69
Q

What depths to purse seiners operate at to catch mackerel?

A

> 20 m

70
Q

What do Norwegians fish?

A

Mackerel at the overwintering grounds close to shore

71
Q

Who uses gill nets?

A

Spain and Norway

72
Q

Who uses lines and jigs?

A

Norway and the UK

73
Q

Who tends to pair trawl?

A

Ireland and Faroe islands

74
Q

Where is traditionally the highest catches of mackerel being caught?

A

North Sea around the Shetland islands, west coast of Scotland and Ireland

75
Q

Where is recent years is there high catches of mackerel?

A

in Icelandic and Faroese waters , where there was no reports of catches prior to 2006

76
Q

In 2013, how much of the total reported landings were in Iceland?

A

Almost half

77
Q

When was mackerel catches reported for the first time in Greenland?

A

2011

78
Q

What was the EU TAC quota for mackerel in 2021?

A

119,573 tonnes

79
Q

What was the Irish mackerel quota in 2021?

A

60,847 tonnes

80
Q

When can Irish fishermen fish for mackerel in regards of the quota?

A
80
Q

When can Irish fishermen fish for mackerel in regards of the quota?

A

Can be fished in UK waters 4.a during periods of:
-1st Jan -14th Feb
-1st Aug - 31st Dec
(2021)

Fisheries Monitoring and Assessment (10 decks)

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