Salmon Friendly Docks

Shallow coastal habitats are critical for Pacific Salmon, especially when juveniles first migrate to saltwater. They use shallow nearshore areas for refuge and finding food, and during this period, healthy eelgrass meadows and complex habitat are vital.

Under traditional docks and overwater structures, however, it can be dark and barren – eelgrass can not thrive, nor can all the critters that depend on it. The lack of light also impacts salmon behaviour, as they naturally avoid dark areas and end up using deeper waters where they are more exposed to predators and don’t have the food resources they need. To learn more about these impacts, see our post on Salmon and Shoreline Modification you can also learn how to protect eelgrass habitats while you are boating in this post.

Fortunately, with a few considerations, there are ways we can build docks that that minimize their impact to the coastal environment and to Pacific salmon.

The best way to protect the shallow coastal habitat is to avoid building docks in the first place.

If you are thinking about building a personal dock, consider if you can store your boat at a marina or at home on land. Could you share a dock with your neighbours? After all, it is a large endeavour to have a dock built. It requires authorization and there are regulations for building and compensation for habitat damage, especially when vital habitat like eelgrass is present. Along with reducing your footprint, sharing a dock also reduces costs and maintenance!

If you must build a dock, make it salmon friendly. Here’s how:

Keep it non-toxic – Do not use creosoted or chemically treated footings, which are highly toxic! If retrofitting an existing structure, remove any treated pilings.

Allow the light to make it through – rather than using solid decking, use grating that allows light penetration to the water. This is a relatively simple fix that can even be applied to existing docks by swapping out sections of decking.

Reduce the number of pilings – make the dock span more like a bridge, and keep the bottom of the dock’s deck at least half a metre above the high-water mark. This will also allow more light to shine through and reduces the amount of submerged artificial structures in shallow areas.

Be considerate at night – don’t leave your lights on overnight. Lights at night can affect natural circadian rhythms and expose fish to nocturnal predators. 

To learn more about better docks for salmon, check out this post on the subject by Lake Washington/Cedar/Sammamish Watershed.

Photo Credits: Joey Genovese Unsplash, Meritt Thomas Unsplash

Protecting Eelgrass When Boating

There are simple steps boaters can take to minimize harm to vital marine habitats such as eelgrass. By practicing mindful anchoring and mooring, slowing down, reducing wakes and avoiding running motors in shallow coastal areas, we can protect critical eelgrass habitat and all the life it supports.

Healthy eelgrass meadows increase the resilience of nearshore habitats and also build resilience in coastal communities. Not only is eelgrass an important nursery ground and refuge area for Pacific salmon and forage fish, it also buffers wave energy, reduces shorelines erosion, stabilizes sediment, improves water quality, and sequesters carbon.

One of key threats to eelgrass is careless anchoring. When anchoring, boaters typically seek out calm bays – which, are also the prime location for eelgrass.  Anchoring can scour and damage eelgrass resulting in a reduction in density and extent, and fragmented habitat. It also suspends sediment in the water column that can smother eelgrass reducing its ability to thrive.

To avoid this damage:

Anchor Deeper

Eelgrass only grows in shallow areas, therefore, damage to eelgrass can be avoided by simply anchoring in depths beyond 7 meters.

Avoid known eelgrass habitat

On some Gulf Islands you may find signs, such as the one on the left that delineate eelgrass habitat. You can also mark locations on your GPS for eelgrass beds to avoid them in the future. Plan your boating and check out the following map of sensitive nearshore habitat to avoid in the Strait of Georgia. The green shows where eelgrass is and the brown shows where kelp forests are.

Use Environmentally Friendly Moorings (mid-line float)

Traditional moorings, which consist of heavy chains and anchors, drag and scour the seafloor as the tide ebbs and flows. This scouring of the seafloor leaves circular scars where eelgrass has been scraped away as can be seen in the picture on the right of San Francisco Bay (Kelly et al. 2019).

Instead, environmentally-friendly moorings contain a mid-line float that holds a rope above the seafloor, and therefore will not scour or damage eelgrass. Mooring buoys can be repurposed, but it is best to contact professionals for advice (have your local tidal information and boat specifications when you call). Trotac Marine in Victoria, BC sell parts to create an environmentally-friendly mooring – keep in mind you need a strong cement block to attach it to. See the diagram below of a recommended mooring design provided by Trotac Marine for additional considerations. Even if you’re anchoring away from eelgrass habitat, these moorings help reduce drag and suspended sediment in the water column.

Mind Voluntary No-Anchor Zones

Voluntary No- Anchor Zones have been implemented in Jefferson County, Washington State, USA, with the aim to reduce boat traffic and reduce damage to sensitive habitats. They have experienced a 98% compliance rate! And now you can look for these marker buoys in Canada – it is now a collaborative transboundary initiative! The first ones have been placed around an eelgrass restoration site on Bowen Island, with the help and input by local community members and SeaChange Marine Conservation Society.

Learn More About Restoring Eelgrass

Photo credits: Jeff Skinner, (Kelly et al. 2019) Coastal Photography Studio.