NATURES

(Project 199105500)

Natural Rearing Enhancement System

Resource Enhancement and Utilization Technologies DivisionNorthwest Fisheries Science CenterNational Marine Fisheries Service

2725 Montlake Boulevard E.Seattle, Washington

Goals

• Increase postrelease survival

• Minimize morphological and behavioral divergence from wild fish

Summary of Major Results Achieved

• Seminatural raceway habitat– Induced wild-like behavior and coloration– Increased instream survival

• Predator avoidance conditioning– Increased instream survival– Increased predator recognition

• Ecological interactions– Improved competitive ability– Reduced behavioral divergence

• Feeds– Improved foraging skills

• 12 published papers

Objectives

1. Evaluate the independent and interactive effect of NATURES seminatural raceway habitat variables on chinook salmon smolt-to-adult survival.

2. Evaluate the effect of NATURES predator avoidance conditioning on chinook salmon smolt-to-adult survival.

3. Quantify the effects of hatchery steelhead reared in NATURES and conventional environments on the growth, survival, condition, and emigration of naturally-reared steelhead and chinook salmon.

4. Determine the effects of NATURES rearing on the behavioral development of juvenile steelhead and the effects of competition with naturally-reared salmonids.

Address RPA 170-173, and 184

Carson NFH Experiments (Obj. 1 & 2)

• Seminatural Raceway Habitat

• Predator Avoidance Conditioning

Experiment evaluating the independent and interactive effects of NATURES Seminatural Raceway Habitat

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Eight rearing treatments

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Full factorial experimental design

T1 T2 T3 T4 T5 T6 T7 T8

Seminatural Raceway Habitat Experiment

Response variables• Growth• Health• Cryptic coloration• Brain development• Predation bioassay• Instream survival• Smolt-to-adult survival

Predator Avoidance Conditioning Experiment

Rearing treatments• No antipredator conditioning

• Antipredator conditioning

Response variables• Instream survival

• Smolt-to-adult survival

The effects of NATURES rearing environments on ecological interactions between naturally and hatchery-reared steelhead (Obj. 3 & 4).

Rationale:• Ecological interactions between wild and

hatchery-reared salmonids have been implicated in stock declines.

• NATURES rearing affects competitive ability and agonistic behavior (Berejikian et al. 2000, 2001).

Experimental Facilities

Quasi-natural stream(40 x 6 m)

Behavior observationflumes

How do hatchery rearing environment and stocking density affect interactions with

naturally-reared steelhead parr?

• Stock conventional and NATURES steelhead parr at different densities with naturally-reared steelhead and chinook parr.

• Evaluate habitat use, agonistic behavior, feeding, growth, survival, and dispersal of naturally-reared steelhead parr.

Expected Results• Determine the combination of seminatural raceway

habitat components that maximize smolt-to-adult survival.

• Determine if predator avoidance conditioning increases smolt-to-adult survival.

• Quantify effects of NATURES-reared steelhead on the growth, survival, and dispersal of natural steelhead and chinook parr.

• Quantify effects of NATURES-reared steelhead on the habitat use, behavior, and feeding of natural steelhead and chinook parr.