fish conservation and managementfaculty.forestry.ubc.ca/hinch/486/2019/lectures/15... · •...
TRANSCRIPT
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Fish Conservation and Management
CONS 486
Hatchery IssuesMore fish in the wild is good, right?
Chapter 8 Ross
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Major theme: Linking science to conservation & management
• Harvest regulations
• Managing fisheries & habitats
• Protecting populations & habitats
• Restoring populations & habitats
• Fisheries exploitation data
• Applied life history data
• Human dimensions: socio-economic data
• Physiology
• Behaviour
• Population ecology
• Ecosystem ecology
• Habitat data (limnology, oceanography)
• Life historyBasic science
Applied science
ManagementConservation
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Hatcheries: TopicsPurposes of hatcheries:
• introduce new species into either existing or new aquatic systems for fisheries purposes (as a target species or forage)
• supplement an existing population for fisheries purposes
• re-establish (restore) native fishes that were eliminated or supplement fishes that are threatened with extinction
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Hatcheries: types• Production hatcheries: enhance or create fish production for commercial and
recreational fisheries
- Release fry or juveniles into natural environments
• Conservation hatcheries: production maintains self-sustainable local wild stock
- Supplement an existing threatened population
- Re-establish extirpated native fishes
• Many hatcheries serve the dual roles of conservation and production
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Hatcheries
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-fish may be released as juveniles from the hatchery and return on their own as adults (eg salmon)
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- fish may be trucked and released in other locales as juveniles or adults
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• Hatcheries have played a role in maintaining/introducing non-native fishes outside their natural ranges (from Ross)
Introducing a new species into an existing or new aquatic system for fisheries purposes (as a target species or forage)
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Issues:
• introduced species can displace (through competition and/or predation) native species, for example:
• brown trout (originally from europe) introduction have caused the decline of many north american salmonid populations (brook trout, cutthroat trout, Dolly Varden)
• brook trout (originally from eastern NA) introduction have caused the decline of native cutthroat trout populations
• rainbow trout (originally from western NA) introduction have caused the decline of native brook trout
Introducing a new species into an existing aquatic system for fisheries purposes (as a target species or forage)
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Issues:
• non-natives often push natives out of their marginal habitats – in Sweden, native brown trout outcompeted in colder water high elevation areas by introduced brook trout, but brown trout able to outcompete the brook trout in lower elevation warmer systems
• introduced species sometimes mate with natives, and if fertile, the offspring often have disrupted gene sequences (called introgressive hybridization) which often makes the hybrid less adapted to their environment
Introducing a new species into an existing aquatic system for fisheries purposes (as a target species or forage)
Brown trout (Salmo trutta) Brook trout (Salvelinus fontinalis)
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Issues:
• introductions into reservoirs and ponds probably represents the most consistently productive uses of hatchery fishes (lots of these systems – see pg 193 figure 8.2 Ross – some states have > 150,000 ponds (small lakes))
• native fishes are usually not disturbed (especially in ponds, no chance of escape)
• even if fish can escape, species that do well in pelagic reservoir and pond systems, tend to not do well in river systems which is where they may escape to
• nor will native river dwellers perform well in the reservoirs
Introducing a new species into a new aquatic system for fisheries purposes (as a target species or forage)
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OVERVIEW
• Put-and-take: raise non-fertile fish to catchable size and release
• Put-grow-and-take: raise fish to fry/fingerling stage and release into environment where they grow to catchable size
• Freshwater Fisheries Society of BC operates the BC provincial hatcheries (different from DFO hatcheries)
– Stock 1000+ lakes per year, mostly rainbow trout
• $7 million budget – funded by angling licenses
Introducing a new species for fisheries: Fisheries supported by hatchery additions of ‘non-reproductive’ stocks
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DETAILS
Put-and-Take
• 120 lakes in BC are put-and-take
– E.g., ~ 12 lakes near Vancouver stock rainbow trout
Advantages
• Can utilize poor habitats unsuited for long-term survival/reproduction
– Provide fishing near large population centers
• Releasing large fish so produce angler satisfaction
• Relieve fishing pressure on wild/native stocks
Disadvantages
• Total maintenance of the fishery by hatchery production of non-natives can be expensive
– E.g., 70% of Mass. Fish & wildlife budget goes to put and take trout hatchery program
Introducing a new species for fisheries: Fisheries supported by hatchery additions of ‘non-reproductive’ stocks
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Put-Grow-and Take
Advantages:
• More natural fishing experience
– e.g., rainbow trout in many of B.C’s interior lakes
• Cheaper to raise fish to fry or fingerling sizes than to catchable sizes
Disadvantages:
• Affect wild fish?
– 50% of trout fry released in BC are either triploid, sterilized or all female; therefore some hatchery additions can become reproductive
– So lower chance of negative effects on wild fish?
Introducing a new species for fisheries: Fisheries supported by hatchery additions of ‘non-reproductive’ stocks
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Supplementing existing populations for fisheries
• e.g. annual production: Chehalis River Hatchery, BC
• one hatchery releases a lot of fish!!
Chum - 1,000,000 fed fryChinook - 3,300,000 fed fryCoho - 1,100,000 smoltsSteelhead - 89,000 smoltsCutthroat - 24,000 smolts
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There are a lot of supplemental salmon hatcheries
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Supplementing existing populations for fisheries:Hatchery releases in BC
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Supplementing existing populations for fisheries:% fish captured from hatcheries in BC
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Increasing numbers of released Pacific salmon smolts does not always lead to more adults
Why?
• Predator build-up
• Selection for “inappropriate” behaviours
• Reaching density dependence
Supplementing existing populations for fisheries
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• How well do hatchery fish perform compared to wild counterparts?• Not as good!!
• Why? •Hatcheries select for fish that do well in hatcheries!
• learn to feed on man-made diet in plastic trays, don't need to know how to avoid predator
• natural selection on wild fish favours fish that can avoid predators and forage on wild food
• lots of research showing that hatchery rearing can affect schooling behaviour, morphology and brain development
Supplementing existing populations for fisheries
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(Mill
ion
s X
10
)
Supplementing existing populations for fisheries:Are there negative impacts on wild fish?
(hurting those you want to help!)
• If fish are near or at their environmental carrying capacity further additions of supplemental fish can negatively affect wild fish abundance or growth
Hilborn and Eggers (2001)
• Ocean productivity shift (PDO shift) in 1976• High primary productivity henceforth• Carrying capacity ~ 2 M fish???
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• Hide effects of natural declines
– 70% of coho production in lower mainland comes from hatchery stocks
– 30% from wild stocks (PFRCC 2002)
• This hides the fact that 20% of all small streams have disappeared in lower mainland
• 48 - 62% of streams are classified as endangered (FRAP 1997)
• All were productive wild coho streams!
Supplementing existing populations for fisheries:Are there negative impacts on wild fish?
(hurting those you want to help!)
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Core Conservation purpose of hatcheries:
Re-establish (restore) native fishes that were eliminated or supplement fishes that are threatened with extinction
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Captive Breeding Programs
• When a stock/species is near extinction…
– Bring some (all?) individuals into a hatchery and facilitate breeding, rearing or spawning, then transplant back to wild settings
• May take generations of fish before numbers increase inbreeding depression and artificial selection could occur
– Both of which could reduce natural genetic variability and reduce chances of re-stocking success
• Unless the original problem that caused the problem is rectified, recovery may not ever happen
– E.g., Cultus sockeye
• But some successes: e.g., Aurora Trout
Re-establish (restore) native fishes that were eliminated or supplement fishes that are threatened with extinction
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Aurora trout (Salvelinus fontinalis timagamiensis)
• Unique variant of the Brook Trout
• Native to a few remote lakes north of Sudbury, Ontario
• Original native populations were extirpated as a result of acid rain in 1960s
• Using captive breeding stock were re-introduced into some lakes in the 1990s following improvements in water quality
• Have since become self-sustaining populations!
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• Distribution of Aurora Trout
• Red dots: native populations
• Black dots: introduced populations
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Future of Hatcheries
• There is a huge debate, some want them abolished others to expand
• They can provide new fishing opportunities in new systems
• Help recover endangered gene pools
• For supplemental hatcheries: need to be part of a larger mgt strategy, not the focus
– E.g., recovery of stocks not supplementing a fishery
• Need the ability to adaptively manage them to see if they are meeting mgt objectives, and be prepared to reduce production or shut hatcheries if objectives not met
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Future of Hatcheries
• An Oregon judge recently ruled that he could see no evidence that wild/hatchery differed in their fundamental aspects, therefore he…
– ‘Delisted’ the wild stocks from their ESA listing
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Coming up next…
• the distinction of ‘extinction’
• the impermanence of ‘imperilment’
• the reality of ‘risk’
• And, the speciousness of ‘special concern’