New research shows the impact log booms have on salmon habitats in the Fraser Estuary

In the Lower Fraser River and Estuary, log booming, where bundles of logs are tied up and stored along the river bank, is perhaps the most widely observable industrial activity. Despite the well known importance of the habitat in this area to juvenile salmon, very little research has been done to look at the potential impacts of this activity on salmon habitats. 

Log booms are often observed to ground at low tide in the estuary, with several potential impacts to salmon habitats. A new study, which was conducted across the Lower Fraser and Estuary in 2019 and 2020, was one of the only studies to look at potential impacts on habitat from log booms. 

The study, “Effects of log booms on physical habitat, water quality, and benthic invertebrates in the lower Fraser River and estuary,” was published in Canadian Journal of Forest Research. Researchers looked at sites ranging from New Westminster downstream to the ocean in the Main Arm and the South and North Arms of the Fraser. They compared sites impacted by log booms as well as reference sites and looked at several different variables potentially important to juvenile salmon in these areas: invertebrates, water quality, compaction and marsh vegetation. The study also analyzed the percentage of shoreline occupied by log booms throughout the study area. 

The North Arm was found to be the primary area impacted by log booming, with over 50% of the shoreline occupied by log booms, whereas very little log storage occurred in the Main or South Arms. The primary impacts from log booming activity were a large decrease in the abundance of benthic invertebrates, a key food source for juvenile salmon, with  four times greater abundance at reference sites relative to active log booming areas. Compaction was found to be significantly higher in active sites, with 80% of sites compacted versus 16% for reference sites. Marsh vegetation was also found to be reduced by 16% at active sites, however this difference was not found to be significant, likely due to our small number of sites limiting statistical power. 

This study demonstrates a clear impact on juvenile salmon habitats in an area that is important to a diversity of species and populations from throughout the Fraser River on their downstream migration as juveniles. There is a guidebook which was created for this industry, “Environmentally Sustainable Log Handling Facilities in British Columbia,” which was published over 20 years ago in 2003; it describes “Best Management Practices (BMP) for environmentally sustainable and sound industrial practices” associated with the log handling industry in BC. 

These best practices include only storing them in areas where grounding will not occur, preventing compaction and its associated impacts on vegetation and invertebrate abundance. 

Based on the results of our study, it seems clear that these BMPs have not been followed or enforced in the Lower Fraser and Estuary at the sites included in the study, and likely more broadly. The Lower Fraser and Estuary provides important habitats for juvenile salmon which support populations throughout a quarter of the province. If we simply followed the best practices and moved log booming out of the estuary we could reduce these impacts on important species such as Chinook salmon.  

This paper has been selected as the editors choice for this month and is currently available free online.

Citation

Noah Kussin-Bordo, Scott G. Hinch, Yeganeh Asadian, and David C. Scott. 2024. Effects of log booms on physical habitat, water quality, and benthic invertebrates in the lower Fraser River and estuary. Canadian Journal of Forest Research. 54(8): 918-931. https://doi.org/10.1139/cjfr-2023-0163

Abstract

To facilitate the movement and processing of timber in some regions of the Pacific Northwest, logs are tied together to form large rectangular rafts (often called “booms”) which are transported and stored in aquatic environments. In the lower Fraser River, British Columbia, some reaches have >50% of shoreline with adjacent log booms, yet our understanding of the effects of log booms on habitats and biota is very limited. We compared sites that have never had log booms to nearby ones with active boom storage occurring to examine differences in environmental characteristics. In contrast to reference sites, nearly all active sites had compacted sediments and little vegetation coverage, likely caused by logs “grounding” onto benthic environments due to tidally influenced water level changes. Total benthic invertebrate abundance was higher at reference sites which had relatively more Amphipoda and Trichoperta, but fewer Haplotaxida, compared to active sites whose compacted and more detrital-laden sediments should favour haplotaxids. Water quality variables generally did not differ between reference and active sites. Grounding of log booms and contact with the below substrate is in contradiction of best management practices and has clear effects on the physical habitat and biota of the area underneath booming sites.

Authors and affiliations

Noah Kussin-Bordo^1,2
Scott G. Hinch¹
Yeganeh Asadian³
David C. Scott^1,4

1. Pacific Salmon Ecology and Conservation Laboratory, Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T1Z4, Canada
2. First Nations Fisheries Council of British Columbia, 320-1200 West 73rd Avenue, Vancouver, BC V6P 6G5, Canada
3. Musqueam Indian Band, 6735 Salish Drive, Vancouver, BC V6N 4C4, Canada
4. Raincoast Conservation Foundation, P.O. Box 2429, Sidney, BC V8L 3Y3, Canada

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