Finding Solutions

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The state governments of Maine, Massachusetts, and New Hampshire are working together to understand the rainbow smelt’s status and threats, and to plan a regional conservation effort for the species. Scientific research by the three-state collaborative focuses on the status of the smelt population and the condition of spawning areas in streams, which may be a key factor in the rainbow smelt’s decline.

Multi-State Collaborative to Develop and Implement a Conservation Program for Rainbow Smelt

In 2004, the National Oceanic and Atmospheric Administration listed the rainbow smelt as a federal Species of Concern. The rainbow smelt is a small fish that lives in estuaries and offshore waters, and spawns in shallow freshwater streams each spring. Its numbers have dropped dramatically during the last fifteen to twenty years for reasons that are not well understood.

Because loss and degradation of spawning habitat appears to be a major factor in the population decline, scientists from state agencies are studying human impacts on rivers and streams where rainbow smelt currently spawn or may have in the past. Based on the scientific findings, the states will develop a conservation plan to address the impacts and promote recovery of this imperiled species.

Scientific Research Program

Spawning Locations

Which rivers and streams are used presently by rainbow smelt for spawning?
State agencies in Maine, Massachusetts, and New Hampshire have surveyed streams to identify potential spawning sites and to assess which of those are currently used by rainbow smelt. We combine and map the data to show where rainbow smelt are currently known to spawn.

Historical Data

How abundant were rainbow smelt in the past, and where did they spawn?
We are compiling historical datasets on smelt abundance and spawning locations. We are analyzing the datasets to understand long-term changes in the rainbow smelt population.

Movement

How often do rainbow smelt enter and leave streams and rivers?
Using small radio tags and an antenna system, we track the movements of rainbow smelt in estuaries. We are finding that many of them return to spawning areas each night on the incoming tides.

Predictive GIS Model

Based on scientific analysis, where could we expect to find suitable spawning habitat for rainbow smelt?
We are analyzing characteristics of coastal watersheds of the Gulf of Maine, such as their proportion of forested land, human population density, and percentage of area covered by pavement and other impervious surfaces. Based on this analysis, we are determining thresholds for urban and agricultural land use, impervious surface, and population density for watersheds that can support rainbow smelt spawning habitat. With this information, we are building a mapping tool to identify other streams that are potentially suitable as spawning habitat for rainbow smelt.

Fishing Pressure

How many rainbow smelt are caught by fishermen?
We collect this information in two ways:

(1) Each winter when smelt camps are set up on the frozen rivers of Maine and New Hampshire, we conduct a creel survey. The word creel refers to a woven wicker basket that anglers wore in the past to store their catch while they fished in rivers. In our creel surveys, state biologists ascertain daily catch at winter smelt camps and collect information about the age and gender composition of the catches. Two to three times a week, we visit camps on a rotating basis to collect information from anglers about the time they spent fishing and the number of fish they caught. We count, measure, and determine the sex of smelt that have been caught. We take scale and fin samples from some fish for age and genetic analysis.

(2) Anglers can contribute to the project even if a creel surveyor is not present by completing a Winter Smelt Survey card (see right). Using these cards, anglers can record their catch for the day and drop the card in a collection box. When the camps close for the season, we collect the survey cards and record the data.

We analyze the data from the creel survey and compare it with historical data to understand annual trends in population size.

Long-Term Index Stations

What are the environmental conditions at spawning sites? What are the demographic, genetic, and disease characteristics of rainbow smelt at these sites?

At 16 rivers and streams known to support spawning by rainbow smelt, we monitor:

  • water temperature, dissolved oxygen, nutrients, pH, salinity, and turbidity,
  • algae (periphyton) that could smother smelt eggs,
  • heavy metals that could lead to egg mortality and impair development of young smelt, and
  • abundance and diversity of insect larvae and other macroinvertebrates as an indicatorĀ of stream health.

At these Long-Term Index Stations, we use large fyke nets to catch rainbow smelt during the spawning season. We count, measure, and identify the sex of the fish; take samples of their scales, which we later use to determine age; and collect samples of their fins for genetic analysis. The size and age data will be used to develop indices of population abundance. The University of Maine Animal Health Laboratory screens the fish for diseases caused by bacteria, viruses, and parasites.

Conservation and Restoration Plan

Restoration of spawning habitat in a New England stream.

Using scientific information from our collaborative efforts, the state agencies of Massachusetts, New Hampshire, and Maine are developing a regional conservation and restoration plan for rainbow smelt. Each state is determining the most important threats from water quality, fishing pressure, or habitat alteration facing its smelt populations. We are also identifying regional threats, potentially including rising ocean temperature and marine bycatch, and site-specific threats and management recommendations, such as redesigning stream culverts to allow fish passage.

When completed, the conservation and restoration plan will present a comprehensive, regional strategy to address the threats and to restore populations of rainbow smelt in the Gulf of Maine. The plan will identify habitat restoration projects and management actions to be pursued as immediate priorities, and it will propose future projects and collaborations.

The regional conservation plan for rainbow smelt may include some or all of the following strategies:

  • Replacement of culverts that block fish passage
  • Dam removal
  • Stock enhancement
  • Remediation of stormwater pollution by using pervious pavement, redesigned sewage treatment systems, andĀ other approaches
  • Reduction of nutrient inputs to streams
  • Mitigation of siltation
  • Restoration of spawning habitat, including stream channels, substrates, and stream flow
  • Reduction of mortality in fisheries

These photographs show an example of a habitat restoration project. Before the restoration project, an undersized, collapsed culvert prevented smelt from swimming upstream to an area suitable for spawning. After the project, a large, well-designed culvert enabled smelt to reach the spawning habitat.

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