Application of IP Models for Salmon and Steelhead Recovery Planning in California

Transcription

1 Application of IP Models for Salmon and Steelhead Recovery Planning in California Brian Spence and David Boughton NMFS Southwest Fisheries Science Center

2 Uses of IP models in technical recovery planning Hypothesize historical population structure - Identify independent populations: a collection of one or more breeding groups whose population dynamics and extinction risk are not substantially altered by exchanges of individuals from other populations (McElhany et al. 2000) Development of biological viability criteria

3 Ocean Land Populations Migrants

4 Problems Lacked data on historical population abundance for most coastal streams. Little information on straying rates. Needed method for estimating the relative carrying capacities of different watersheds for each listed species Ocean Migrants Land Populations

5 ESUs in NCCC Recovery Domain Humboldt Bay California Coastal Chinook ESU Northern Califonia Steelhead DPS Punta Gorda Point Arena Central California Coast Coho ESU Central California Coast Steelhead DPS San Francisco Bay Map Area 0 Monterey Bay km

6 ESUs in SONCC Recovery Domain (coho salmon only)

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8 Russian River Basin Coho IP Coho Upper Limits < Mean August Air Temp. (C) < < > 22

9 Basin-level IP values Reach-level IP taken as geometric mean of the three suitability values Basin-level IP, referred to as IPkm, equals sum of all accessible stream kilometers weighted by their IP value

10 Pudding Creek Hare Creek Jug Handle Creek Caspar Creek Russian Gulch (Me) Little River (Me) Albion River Big Salmon Creek Navarro River Greenwood Creek Elk Creek Alder Creek Brush Creek Garcia River Gualala River Usal Creek Cottaneva Creek Hardy Creek Juan Creek Howard Creek DeHaven Creek Wages Creek Ten Mile River Noyo River Big River NCCC Coho Populations Functionally Independant Independent Potentially Independant Independent Dependant Dependent Russian River Napa River Russian Gulch (S) Salmon Creek (S) Americano Creek Stemple Creek Walker Creek Petaluma River Novato Creek Lagunitas Creek Corte Madera Creek Redwood Creek (Ma) San Leandro Creek San Lorenzo Creek San Mateo Creek Pilarcitos Creek San Francisquito Creek Tunitas Creek San Gregorio Creek Stevens Creek Pescadero Creek Gazos Creek Waddell Creek Scott Creek San Vicente Creek San Lorenzo River Sonoma Creek Miller Creek San Pablo Creek Alameda Creek Coyote Creek Guadalupe River Aptos Creek Soquel Creek

11 Lessons learned For our purposes, IP models provided a reasonable basis for hypothesizing about historical population structure For CCC coho salmon, addition of a temperature mask was effective in screening out historically unsuitable habitats However..

12 Cautions when extending IP models Model parameters and/or suitability curves are not necessarily exportable to other geographic regions. - e.g. Coho temperature mask

13 Russian River Basin Coho IP Coho Upper Limits < Mean August Air Temp. (C) < < > 22

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16 Some generalizations? The greater the area and/or environmental heterogeneity of the landscape being modeled, the higher the probability that general IP models will perform poorly. (e.g., geology, elevation, vegetation, climate) The nearer the periphery of the species range, the more likely that local factors will emerge as important.

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18 Final Thought IP as a concept first, then a model The goal is to identify a suite of variables that are dominant in controlling the expression of habitat characteristics suitable to a particular species and life stage within a given region

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22 Self-recruitment Population Classification Ephemeral Functionally Independent Dependent Potentially Independent Viability-in-Isolation

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24 Population Demarcation Breaks defined a priori Based on: Ocean entry Within-basin Substantial separation of spawning areas Major environmental/ecological variation Evidence of divergence (genetic, life history, etc.)

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27 Caveats Parameters, suitability curves, etc. appropriate to one local region may be inadequate/inappropriate elsewhere. Example: Temperature mask used for coho in CCC ESU seemed to appropriately mask out unsuitable areas (may reflect major changes in vegetation). In SONCC, the temperature mask may not perform in more interior regions. Complicated by unique local hydrology (spring-fed systems, snowmelt systems) that moderates stream temperatures. Hydrology: relationship between mean annual discharge and summer low-flow discharge likely change from north-south, west-east, and with elevation. Example: Santa Cruz Mountains - Majority of rain falls over narrow window (Dec-Feb) - Relatively steep terrain leads to more rapid runoff - Preliminary field work suggests flow needed to initiate a coho-bearing stream may be 2-3 time greater than in Oregon model

28 Population Classification Extension of independent population concept of McElhany et al. (2000) Independent population is a population whose probability of extinction is negligibly affected by interactions with other such populations Viability-in-isolation Function of population size, etc. Self-Recruitment Measure of (demographic) independence

29 Viability-in-isolation Assume that population size is a good proxy for viability Assume that habitat measured with intrinsic potential (IP) is proxy for population size

30 Self-Recruitment Fixed homing rate Simple dispersal model Self-Recruitment = % native spawners Threshold absolute threshold difficult to assess relative threshold: source v. (pseudo-)sink

31 Other IP parameters that likely show Hydrology regional variation Gradients in relationship between mean annual discharge and summer base flows - North-south - East-west - Elevational - Local geology/geomorphology - Climate-vegetation interactions