Measuring the health of Mt. Tam

Maintaining a healthy, vibrant and diverse Mt. Tam begins with understanding how key ecological resources are faring, and how we can better care for this iconic and beloved place.

One Tam partners and Bay Area scientists have come together to try to answer the question: How healthy are Mt. Tam's natural resources?

Biodiversity

Measuring the health of Mt. Tam

Maintaining a healthy, vibrant and diverse Mt. Tam begins with understanding how key ecological resources are faring, and how we can better care for this iconic and beloved place.

One Tam partners and Bay Area scientists have come together to try to answer the question: How healthy are Mt. Tam's natural resources?

Landscapes

Mt. Tam

Wednesday, December 31, 1969, : Park Stewardship Marin

Learn More

Event Type: Educational and Interpretive
Mt. Tam

Wednesday, December 31, 1969, : Park Stewardship Marin

Learn More

Event Type: Educational and Interpretive
Mt. Tam

Wednesday, December 31, 1969, : Park Stewardship Marin

Learn More

Event Type: Educational and Interpretive
Mt. Tam

Wednesday, December 31, 1969, : Park Stewardship Marin

Learn More

Event Type: Educational and Interpretive
Mt. Tam

Wednesday, December 31, 1969, : Park Stewardship Marin (CANCELED)

Learn More

Event Type: Educational and Interpretive
Mt. Tam

Wednesday, December 31, 1969, : Park Stewardship Marin

Learn More

Event Type: Educational and Interpretive

Measuring the health of Mt. Tam

Maintaining a healthy, vibrant and diverse Mt. Tam begins with understanding how key ecological resources are faring, and how we can better care for this iconic and beloved place.

One Tam partners and Bay Area scientists have come together to try to answer the question: How healthy are Mt. Tam's natural resources?

Threespine Stickleback


What is Healthy?

The desired condition for threespine stickleback is that they are present in suitable, accessible water bodies. The current and historical extent of threespine stickleback in the One Tam area is unknown, but they are less widespread than steelhead. Of the 110 miles of stream in the One Tam area of focus, approximately 40 miles could be characterized as the kind of slow and low gradient streams this species prefers. These 40 miles, along with the Marin Municipal Water District reservoirs, are currently our best guess at the baseline distribution of stickleback on Mt. Tam.

What Are the Biggest Threats?

  • Historic hydrological changes and habitat loss that have affected anadromous fish migration, increased sedimentation, and reduced the number of pools and other critical habitats
  • Current hydrological changes and habitat loss including water withdrawals, drought, channel incision, and a loss of downstream floodplain connectivity
  • Ocean-related factors such as over-harvesting of salmonids as well as their prey (e.g., sardines) and changes to ocean food webs related to climate change
  • Potential invasive aquatic species including exotic mollusks such as New Zealand mud snail (Potamopyrgus antipodarum) and the spread of invasive Japanese knotweed (Fallopia japonica)
  • The effects of climate change such as higher water temperatures, longer droughts, more intense rainfall, and disruptions in the ocean food web

What is The Current Condition?

The current condition is Good, as we believe that stickleback currently occupy all suitable stream habitat, plus Lake Lagunitas.

What is the Current Trend?

The current trend is No Change based on the limited data available on the distribution of threespine stickleback in the One Tam area of focus.

Downloads
Anadromous Fish Indicator Overview

Learn More

Measuring the health of Mt. Tam

Maintaining a healthy, vibrant and diverse Mt. Tam begins with understanding how key ecological resources are faring, and how we can better care for this iconic and beloved place.

One Tam partners and Bay Area scientists have come together to try to answer the question: How healthy are Mt. Tam's natural resources?

Steelhead Trout


What is Healthy?

Living in both estuarine and stream habitats that vary in depth, velocity, temperature, and shelter, steelhead are not as dependent on stream habitat conditions for survival as coho salmon. To persist indefinitely, steelhead trout should occupy more locations in the Mt. Tam area of focus and should migrate to the ocean in numbers sufficient to allow a viable number of adult steelhead to return each year and spawn. The National Fish and Wildlife Service recovery plan for this species (NMFS, 2012) lists specific goals for numbers of spawners and redds (nests), and smolts (young fish migrating out to sea).

What Are the Biggest Threats?

  • Historic hydrological changes and habitat loss that have affected anadromous fish migration, increased sedimentation, and reduced the number of pools and other critical habitats
  • Current hydrological changes and habitat loss including water withdrawals, drought, channel incision, and a loss of downstream floodplain connectivity
  • Ocean-related factors such as over-harvesting of salmonids as well as their prey (e.g., sardines) and changes to ocean food webs related to climate change
  • Potential invasive aquatic species including exotic mollusks such as New Zealand mud snail (Potamopyrgus antipodarum) and the spread of invasive Japanese knotweed (Fallopia japonica)
  • The effects of climate change such as higher water temperatures, longer droughts, more intense rainfall, and disruptions in the ocean food web

What is The Current Condition?

Steelhead trout are in Poor condition. Stream occupancy numbers are very low. The eight-year average for spawners and redds is only approximately 11% of the NMFS recovery target for Lagunitas Creek and 36% for Redwood Creek. One Tam agency biologists believe the Lagunitas Creek target is too high, but conservatively consider the population in Redwood Creek at high risk of extirpation. Similar concerns exist about the smolt target for Lagunitas Creek, and few data exist on steelhead smolt abundance in Redwood Creek.

What is the Current Trend?

The current trend is No Change for smolt estimates, and there is no evidence to determine whether steelhead occupancy has increased or decreased in recent years. Redd counts since 2008 in Lagunitas Creek show no strong trend. Although redd counts in Redwood Creek appear to have declined since 2012, the survey timeframe is short and there’s low confidence in individual run estimates.

Downloads
Anadromous Fish Indicator Overview

Learn More

Pages