Enhancement of Japanese Spanish mackerel

1
Enhancement of Japanese Spanish mackerel
(Scomberomorus niphonius)
Marine Fisheries Research Center
(Osaka prefecture, Japan )
TSUJIMURA Hirotaka
2
Contents
1. Introduction 2. Stock assessment 3. Stock
recovery project Regulation of catch
Seed production and release
3
Japanese Spanish mackerel
(Scomberomorus niphonius)
Family Scombridae (same as
Tuna) Life span 5-6 years Size
1m 10kg Maturation period
2 yeras Feeding habit
Carnivorous (mainly anchovies) Fishing
method Drift gill net
4
Drift gill net
Length 1-4km Height
20-40m Casting time Before sun set
(400 pm) Hauling time
After sun set (700 pm)
5
Japanese Spanish mackerel
(Scomberomorus niphonius)
Japanese name
Sa-Wa-Ra
6
Migration patterns in the Seto Inland
Sea
Spring spawning
Osaka Fisheries Research Center
Winter
7
Migration patterns in the Seto Inland
Sea
Fall
Osaka Fisheries Research Center
Fall
Winter
8
Annual catch of Japanese Spanish mackerel in the
Seto Inland Sea
3,753 t
60 t
9
Simulation results of catch change
Recovery target
800
600
Prohibition of fishing
Catch (ton)
400
Closed season (one month)
200
Release of artificial juvenile fish
No measure
0
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Year
10
Project Enhancement of Spanish mackerel
resources
Regulation of catch
Seed production and
release of juvenile fish
11
Regulation of catch
Closed season Season Various in each area
Length One month or more Mesh size
regulation Enlarged and standardized
(Protection for young fish)
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Seed production and release
Mature fish ( caught by drift gill net)
Collection of eggs and spermatozoa
Release of fertilized egg (Fisherman) Seed
production Raised to 10cm of total length
(Fisheries Research Center)
13
Collection of eggs and spermatozoa
Male
Female
Used two or more males (attention to conservation
of genetic diversity )
200,000 eggs / individual
14
Schedule of seed production
Total length (cm)
Days after hatching
Containing of eggs
(60 hours)
0
Hatching out
0.4
6
Beginning to eat food
Feeding of fish larvae
1.5-2
14-16
Feeding of frozen whitebait
25
4
40
10
15
Seed production 1
10 days after hatching About 10mm of total length
Larvae of Spanish mackerel and other fish larvae
for food (Sea Bream Pagrus major etc.)
Concrete tank Capacity 100-200 tons
Fertilized eggs of other fish are given
every morning
16
Seed production 2
Cannibalism
Whitebait is given once a hour from 500am to
700pm
Whitebait (young fish of Sandlance Ammodytes
personatus)
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Release of juvenile fish
Taking up from concrete tank
Release offshore
40 days after hatching 10cm in total length
18
Investigation of releasing effect 1
Otoliths of larva marked by ALC
Solution of Alizarin Complexone (ALC) for soaking
larvae (10 ppm 12 hours)
(under fluorescence microscope)
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Research of releasing effect 2
Taking out of otolith
Marked otolith
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Research of releasing effect 3
June
September-December
10cm in total length
50-60cm in total length
Number of natural recruit 1,000,000-2,000,000
Release
Catch
Released fish
10-20
Number of artificial-reared juvenile
fish 100,000-200,000
Natural fish
Catch sharing with released fish
21
Annual catch in recent years
Beginning of project enhancement of Spanish
mackerel resources (Regulation of catch and
release of juvenile fish)
1000
Catch (ton)
500
Recovery target
0
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Year
22
Conclusion
1. Simulation
2. Stock recovery project
Regulation of catch
Release of artificial juvenile fish
Enhancement of Japanese Spanish
mackerel