Why Survey Surf Smelt and Pacific Sand Lance?
Surf Smelt (Hypomesus pretiosus) are a schooling fish found in shallow near-shore waters. They range from Prince William Sound, Alaska, to Long Beach, California. They feed on plankton and in turn are preyed upon by larger fish, birds, and marine mammals. Along with other forage fish, like Pacific Sand Lance and Eulachon, they form an important part of the marine food web, sustaining populations of salmon, whales and marine birds. Surf smelt spawn year-round in the upper intertidal zone of mixed sand and gravel beaches. These spawning sites are heavily impacted by shoreline modifications, such as boat ramps, seawalls, culverts, dikes, and riprap, all of which alter the long-term transport of sediment along the shore or bury spawning habitat.
Some surf smelt spawning habitat has been mapped; however, the extent of this habitat remains largely unknown. We conducted a mapping process from 2009-2011 on Mayne Island by surveying some of the Island’s beaches for surf smelt eggs. The survey procedure was the same for surf smelt and sand lance.
Pacific sand lance (Ammodytes hexapterus) spawn on sandy beaches depositing tiny (1mm) eggs in the upper intertidal zone just below the log line. Sand lance is a cornerstone species, connecting the foundation of the food web-plankton-with higher trophic levels-salmon, birds, mammals. Its spawning habitat is particularly vulnerable to shoreline modifications that interrupt the natural sediment building and eroding processes. The instillation of rigid material, such as retaining walls, increases the wave energy hitting the shore and ultimately leads to hardening of the beach (turning a sandy beach into a cobble beach) and increased erosion upstream.
The first step to protecting spawning beach is to determine if the fish actually spawn there.
In January 2009, Pam Thuringer conducted a workshop and training for Pacific sand lance surveys on Mayne. The workshop was well attended and a handful of volunteers toughed out the cold weather to sample seven beaches. Beaches are chosen and sampled based on a science-based methodology. A litre of sand is collected from each beach and filtered through three screen sizes. The egg searching happens in the comfort of home with simple tools: a gold pan, tweezers, magnifying glass, good light and a good pair of eyes. It is tedious searching for 1mm diameter eggs, but once an egg is found the excitement of the search grows.
Forage Fish are the cornerstone of the nearshore marine food web, providing food for numerous marine species. As the extent and location of spawning beaches in B.C. are largely unknown, surveys will identify local examples and assist in their protection from detrimental impactsOur Stewardship page lays out some of the human activities that have an impact on the health of spawning beaches and what we might do to minimise these impacts or elminate them altogether.
The forage fish role in the marine food chain
- Sand lance comprise more than 50% of diet for 31 species of birds, 9 marine mammals, 27 fishes
- Sand lance comprise 10-50% of diet for 9 additional birds, 3 additional marine mammals, about 19 additional fishes
- 72% of chinook salmon diet is sand lance and herring
- 50% of coho salmon diet is forage fish
Locating Sand Lance eggs involved the following
- 3450 square metres of beach were surveyed
- 12 volunteers
- 57 hours of intensive beach site labour
We did not track the hours of gold pan swishing, .. but it was a lot!