Fish Conservation and Management

CONS 486

Hatchery IssuesMore fish in the wild is good, right?

Chapter 8 Ross

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

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

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

Hatcheries

-fish may be released as juveniles from the hatchery and return on their own as adults (eg salmon)

- fish may be trucked and released in other locales as juveniles or adults

• 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)

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)

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)

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)

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

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

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

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

There are a lot of supplemental salmon hatcheries

Supplementing existing populations for fisheries:Hatchery releases in BC

Supplementing existing populations for fisheries:% fish captured from hatcheries in BC

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

• 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

(Mill

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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???

• 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!)

Core Conservation purpose of hatcheries:

Re-establish (restore) native fishes that were eliminated or supplement fishes that are threatened with extinction

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

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!

• Distribution of Aurora Trout

• Red dots: native populations

• Black dots: introduced populations

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

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

Coming up next…

• the distinction of ‘extinction’

• the impermanence of ‘imperilment’

• the reality of ‘risk’

• And, the speciousness of ‘special concern’