Conservation and enhancement of masu salmon in Hokkaido, Japan

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Elijah Powell
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1 Conservation and enhancement of masu salmon in Hokkaido, Japan SoS 2010 in Portland, OR Hirokazu URABE, Yasuyuki MIYAKOSHI, and Mitsuhiro NAGATA Salmon and Freshwater Fisheries Research Institute

2 ,400 1,200 1, No.fish returned (million) 2005 No.fish released(million) Contrast between chum and masu Chum salmon Increase with stocking 2,500 2,000 1,500 1, Coastal catch (ton) 2005 Year 16,000 14,000 No fish releasead (thousand) Year Masu salmon Keep declining despite stocking Hatchery program dose not contribute to masu salmon stock? 12,000 10,000 8,000 6,000 4,000 2,000 0

3 Effectiveness of stocking 5 Smolt : 15~38 g rate(%) 4 3 Smolt Parr Fry Parr : 13~19 g Recovery Mean weight at release (g) Fry : 0.6~1 g (Miyakoshi et al. 2001; 2004; 2006)

4 Contribution of hatchery fish to coastal commercial catches ( ) fish landed Number of :Hatchery-origin :Wild Hatchery fish consistently contribute to stock enhancement But the stock is mainly maintained by wild stock (>74%)

Change of ocean environment Sea of Japan Recreational (Juvenile&adult) Commercial

5 Why did wild populations decrease? Possible reasons 1. Overfishing (including recreational fishing) 2. Change of ocean environment Sea of Japan Recreational (Juvenile&adult) Commercial catch 3. Habitat degradation 4. Fitness decline Habitat loss by dam by hybridization with hatchery fish Channelization All of these would be true

6 Life history of masu salmon Migration barriers Spring Autumn Spawning Habitat degradation (> 1.5 year) Decrease (A part of male) Spring Smolting Stream Ocean

Importance of habitat restoration Suitable rearing habitat for masu salmon Coastal catch (ton) 2,500 2,000 1,500 1,000 500 0 1970 1975 1980 1985 1990 1995 2000 2005 16,000 14,000 12,000 10,000 8,000

7 Importance of habitat restoration Suitable rearing habitat for masu salmon Coastal catch (ton) 2,500 2,000 1,500 1, ,000 14,000 12,000 10,000 8,000 6,000 4,000 2,000 0 No fish releasead (thousand) Year Habitat degradation would considerably influenced the stock level Habitat loss and degradation by dams (at least >12,000 dams exist in Hokkaido (Tamate & Hayajiri 2008)) Loss of spawning and nursery habitat Alteration of substrate condition (armoring & sedimentation) Habitat restoration is critical subject for stock enhancement

8 Estimating the potential recovery in above-dam area 1. Evaluation of habitat quality (NEI value) in the above-dam area through field survey 2. Estimating fish abundance in the above-dam area using fish-habitat regression equation (Urabe 2008) Abundance (g m -2 ) R 2 = P< Urabe (2008) NEI value (J h -1 ) 3. Estimating available area in the above-dam from field survey & GIS analysis 4. Calculating the potential recovery in the above-dam area How many? 17,140 juveniles can recover ( the effect of stocking effort) 2km

Estimating the potential recovery in below-dam area Alteration of sediment transport system by dam such as 1) Blockage of bedload material supply 2) Sediment sorting Armoring Fine

9 Estimating the potential recovery in below-dam area Alteration of sediment transport system by dam such as 1) Blockage of bedload material supply 2) Sediment sorting Armoring Fine sediment Alteration of substrate condition in below-dam area Degradation of habitat for benthic invertebrates Decline of carrying capacity for masu salmon juveniles Decrease of prey

10 Estimating the potential recovery in below-dam area Ken-ichi River watershed 1) Blockade of bedload supply 2) Sediment sorting Dam Degradation of substrate condition in below-dam area If substrate condition is restored, 2km Carrying capacity increase 40%

11 Restoration of spawning habitat and sediment transport system In Shiretoko (World Heritage) Partial removal

12 Can masu salmon stock recover by habitat restoration only? R 2 = P< Hokkaido Island Quantitative evaluation of population recovery by habitat restoration Habitat restoration is quite effective and essential. Riverine environment in Hokkaido has considerably degraded. >12,000 low-head dams exist in Hokkaido (Tamate & Hayajiri 2008) ,140 juveniles can recover ( the effect of stocking effort) 40% increase in carrying capacity If we stop releasing now, stock level of wild populations would critically decrease. Fukushima & Kameyama (2006) We should carefully and effectively use hatchery fish for stock enhancement.

13 Negative impacts of hatchery fish Knowledge in Hokkaido on wild masu salmon Transplant caused decline in returning rate of masu salmon (Mayama 1989) Difference in ecological traits (migration behavior, smolt timing, and seaward migration timing) among wild, domestic, and their hybrid smolts (Koyama et al. 1995, 2007) Genetic property of wild masu salmon populations are different among tributaries even in same watershed (Ohkubo 1992, Kitanishi et al. 2009) Hatchery fish could influence the fitness and genetic property of wild populations

14 Hatchery reform Shift from single enhancement action (releasing) to combination of the wild population recovery and effective hatchery program Recovery of wild populations by habitat restoration Minimize the negative impacts of hatchery fish on wild populations No expansion of releasing areas and number of fish Care for genetic change of the broodstock Captive rearing is strictly restricted under 2 generations (only 1 generation in principle) We should examine the effects of those on stock enhancement and conservation by researches (Partially ongoing)

15 Ongoing and future researches for enhancement and conservation Ongoing researches Estimating the effects of habitat restoration 1) Estimating the potential recovery of spawning habitat using GIS 2) Monitoring the population dynamics after the restoration Monitoring the status of wild populations Monitoring the change in ecological traits of broodstock Future researches (partially ongoing) Researches on establishment of conservation unit 1) Population genetics 2) Development of watershed database (information about ecological attributes and land use)

16 Summary Decline of masu salmon stock in Hokkaido is caused by decrease of wild populations Recovery of wild populations via habitat restoration is quite effective for stock enhancement Combination of wild population recovery and careful hatchery program is essential Hatchery program should be flexibly and adoptively, continuously modified based on scientific knowledge

17 Thank you for your attention!

Chum Salmon recovery in Oregon tributaries to the lower Columbia River. Kris Homel Chum Reintroduction Coordinator

Chum Salmon recovery in Oregon tributaries to the lower Columbia River Kris Homel Chum Reintroduction Coordinator History of decline Chum have broadest distribution Historic runs in Columbia River estimated