Skeena River Estuary Juvenile Salmon Habitat


Introduction

The Skeena is the second largest river in the province, and one of the longest un-dammed rivers in the world. The Skeena River estuary is a unique system in that it does not have a single distinct intertidal delta typical of most estuary systems. Instead, suspended sediments are deposited in shoals along the lower river and the channels which connect the estuary to the open ocean, creating a region of extensive mudflats and shallow, intertidal passages. The estuary mudflats and other intertidal areas have been identified as critical habitats for Skeena River juvenile salmon, as well as important habitat for eulachon and migratory/wintering waterfowl.

Although estuaries provide essential nursery and juvenile rearing habitats, with up to 80% of coastal wildlife species relying on estuaries during at least one stage of their life history, they frequently occur in areas highly valued for industrial development. In the Skeena River estuary, the Port of Prince Rupert is expanding its already extensive commercial activities. Increased vessel traffic associated with newly proposed terminals, as well as potential oil tanker activity from proposed projects such as the Enbridge Northern Gateway, will also increase the possibility of spills and other marine accidents. Estuaries worldwide are often areas of conflict between human resource need and environmental sustainability. A more holistic approach to habitat protection is required, underpinned by a thorough scientific understanding of the roles and vulnerabilities of the different species and habitats in the estuarine environment. In order to implement this approach, there is a need to better understand the cumulative, and often complex, anthropogenic impacts on estuarine environments.

Shown below is an aerial view of the Skeena River estuary looking northeast over Kitson Island, Flora Bank, and Lelu Island. Ridley Island is on the left hand side of the photo. Porpoise Channel is shown as a gap between Lelu and Ridley Islands. The proposed terminal for the Prince Rupert LNG would be located on southern Ridley Island along the north side of Porpoise Channel. The proposed terminal for the Pacific Northwest LNG would be located on Lelu Island along the south side of Porpoise Channel.

A number of local environmental organizations and community groups are working together to try to protect the Skeena River estuary from poorly planned over-development, and to establish the framework for a Skeena estuary management plan. As a part of these efforts, the focus of this study was to analyze the habitat in and around the Skeena River estuary in terms of suitability as valuable or critical habitat to juvenile salmonids. The study was funded by the SkeenaWild Conservation Trust and the Skeena Watershed Conservation Coalition

Design of the Juvenile Salmon Habitat Model

Juvenile salmonid habitat in the Skeena River estuary was modeled based on concepts similar to those from the Ecosystem Diagnosis and Treatment (EDT) methodology used for summer and fall chum salmon in the Hood Canal and the Strait of Juan de Fuca.

The model uses 39 GIS layers, including data on:

  • Slope and exposure of the intertidal zone
  • Oceanic currents
  • Number of and access to estuaries and subestuaries
  • Presence of salt marshes, tidal channels, eelgrass, kelp, and riparian vegetation
  • Watershed areas
  • Shoreline modifications and functional loss of estuarine features and since 1906
  • Competition and predation
  • Epibenthic, neritic, and detrital food sources
  • Dissolved oxygen, temperature, and turbidity
  • Toxic metals and dioxins and furans

This model can provide a "snapshot", both spatially and temporally, of qualitative changes in habitat attributes as they relate to juvenile salmonid survival.

Juvenile Salmon Habitat Conclusions

From the model, the following conclusions were made:

  • The northwest and southwest shores of Kaien Island and the southwest shore of Ridley Island are poor habitat for all salmonid species as a result of industrialization and the attendant shoreline straightening and hardening, industrial pollutants, and poor water quality resulting from sewage and industrial effluents.
  • Flora Bank is excellent habitat for epibenthic feeding salmonid species (e.g., pink, chum, and Chinook). It is in the direct path of approximately 331 million juvenile salmon outmigrating from the Skeena River, of which about 279 million are epibenthic feeders. Therefore, both location and habitat quality make Flora Bank an extremely important juvenile salmon rearing area.
  • Stapledon Island is a high value habitat for all six salmonid species, and is also in the direct path of outmigrating Skeena River juvenile salmonids.
  • The southwest shore of Lelu Island and Delusion Bay are highly valuable habitats for neritic feeding species (e.g., Coho, sockeye, and steelhead).
  • The shoreline segments in the basins on the east side of Kaien Island and on southeast shore of Prince Rupert Harbour provide important nursery and rearing habitats for salmon outmigrating from the local natal streams. While these populations are small, they are important to the overall health and diversity of salmon in the region.

This study has also helped to highlight the need for more detailed and up-to-date information on factors affecting juvenile salmonids in the Skeena River estuary.

See the link for the full Skeena River Estuary Juvenile Salmon Habitat report.

Comments on the Pacific NorthWest LNG Environmental Impact Statement and Environmental Assessment Certificate Application

Based on my studies on salmon habitat in the Skeena River estuary, and my many years of field work in the region, I submitted a critique to the British Columbia Environmental Assessment Office on the Environmental Impact Statement and Environmental Assessment Certificate Application submitted by Pacific NorthWest LNG. This work was supported by the Prince Rupert Environmental Society, the T. Buck Suzuki Foundation, and the United Fishermen and Allied Workers Union - UNIFOR. In summary, my report pointed out the following issues:

  1. Flora Bank Eelgrass Assessment
    • The proponents' surveys underestimate the size of the eelgrass bed, particularly underneath the trestle.
    • The proponent bases their habitat offsetting plans on the underestimated extent, thus reducing the required compensation amount.
  2. Juvenile Salmonid Habitat
    • Flora Bank has the highest juvenile salmonid habitat suitability rating in the region around the proposal.
    • <Flora Bank is in the direct path of approximately 331 million juvenile salmon out-migrating from the Skeena River; these juveniles are unable to cross Chatham Sound to reach "alternative" healthy eelgrass beds on Porcher Island.
  3. Disposal of Contaminated Sediments
    • Some samples have arsenic, copper, and dioxin and furan values which fall between the ISQG value and the PEL value.
    • Dioxins and furans are bioaccumulative, and there may be a bioaccumulative risk to both human and ecological receptors.
    • A full ecological risk assessment is required to predict the probability of adverse effects on the ecosystem as a result of dioxin and furan bioaccumulation.
    • The proponents' sediment dispersal modeling did not use bottom currents, and is therefore not accurate.
    • A full human health risk assessment is required for the area because a significant percentage of the local population are either First Nations or practice subsistence living and thus eat large amounts of country foods.
  4. Marine Habitat Offsetting Plan - Inverness Passage Salmon Migration Corridor
    • It is not justifiable to alter perfectly functional habitat simply because it allows the proponents to meet the amount of habitat offsetting required by their proposed project, or it reduces the amount of material that will need to be disposed on land or at sea.
  5. Marine Habitat Offsetting Plan - Flora Bank Eelgrass Enhancement
    • The "beneficial re-use" of dredgeate is not a justification for disposal of contaminated sediments in a location where they will be dispersed by wave and tidal action.
  6. Marine Habitat Offsetting Plan - Islets Constructed of Perimeter Berms
    • Any proposed structure which interferes with the natural movement of sediments in the marine environment must undergo detailed oceanographic modeling to determine if there will be adverse impacts from the changes in sediment supply.
    • It is not justifiable to "create" habitat in an oceanographically complex environment where the adverse impacts of the structures may outweigh their proposed benefits simply because it allows the proponents to meet the amount of habitat offsetting required by their proposed project, or it reduces the amount of material that will need to be disposed on land or at sea.
  7. Ongoing Disturbance of Flora Bank from Terminal Operation
    • High levels of sedimentation resulting from vessel traffic could cause significant impacts to the ecology of Flora Bank and the organisms dependent on Flora Bank, such as juvenile salmonids.
  8. Effects of Sound from Terminal Construction and Operation on Organisms Other than Marine Mammals
    • Sounds associated with construction and operation of the proposed facility could influence both fish behavior and distribution of schooling, potentially resulting in juvenile fish leaving the Flora Bank nursery habitat prematurely, thus resulting in lost feeding opportunities and potential starvation.
  9. Effects of Overwater Structures on Juvenile Fish
    • Juvenile salmon schools are forced into deeper water by overwater structures, changing their behavior with implications for within-species competition, feeding behavior, and susceptibility to predation.
    • Night time artificial lighting on dock structures can change fish species assemblages and pose increased risk of predation by subsequent changes in night time migration, activity, and location of predators.

See the link for the full comments on the Pacific NorthWest LNG Environmental Impact Statement and Environmental Assessment Certificate Application.

An Example of Cumulative Effects Modeling

Using the juvenile salmon habitat model, the cumulative effects on juvenile salmon habitat by Canpotex, Prince Rupert LNG, Pacific Northwest LNG, the Westcoast Connector pipeline, and the Prince Rupert Gas pipeline were modeled based on the public information provided by the proponents.

Marine habitat offsetting proposals were not included in the model because:

  • Location of habitat is key. Offsetting plans at other locations do not provide the same ecosystem services to the same organisms.
  • Many of the proposed offsetting plans have not been adequately modeled, scoped, or reviewed, and several seem likely candidates for failure.
  • Habitat compensation is not always successful. Good design, proper follow-up, appropriate governmental oversight and compliance monitoring, and often good luck, are all important ingredients for success.

The results of the cumulative effects modeling are shown in the figures below:

In the Ridley Island-Lelu Island-Flora Bank region, there is 32.6 km of shoreline that is utilized by salmon out- migrating from the Skeena River.

  • 18.5 km, or 57%, will be impacted at some level by the proposed industrial developments.
  • Considering the habitat value of the impacted shoreline, the loss of valued habitat to juvenile salmon will be 29%, or over 1/4 of the currently existing habitat.

To view presentations that have been given on the issues of juvenile salmon habitat in the Lelu and Ridley Island region, please view "An Example of Cumulative Effects Modeling: Industrial Development in the Skeena River Estuary" and "LNG in the Skeena River Estuary: What is the Risk to Our Salmon?".