|
Sand Lance Ammodytes
hexapterus
The sand lance and the herring play important roles in pacific
ecosystems as food for other fish, birds and marine mammals.
They are especially important in the diet of juvenile salmon
and nesting seabirds such as the rhinoceros auklet, marbled
murrelet, and tufted puffin. Many of the familiar creatures
along our shore such as the mussels, starfish, crabs and clams
begin their lives as plankton afloat in the meadows of
phytoplankton. Tiny larval sandlance join the plankton and
rely on these massive beds of tiny plants and animals for
food. As they grow, the sandlance converts plankton into fish
tissue. The great schools of sandlance then become targets for
predatory fish, birds and mammals. Squealing flocks of gulls
and diving seabirds often indicate the presence of sand lance
just below the surface.
Sand Lance Distribution and
Migration
The sand lance spends part of its year offshore and inshore
always in very large schools. It has a wide distribution from
southern California to the Sea of Japan and across the Arctic
Ocean.
Sand Lance
Behaviour
Adult
sandlance migrate to sandy-gravel spawning beaches. Adults
wriggle into the sand to deposit eggs near the top of the
beach on high tides between early November and mid-February in
British Columbia (Hart 1973). The fish often become coated in
fine grains of sand and go unnoticed. The tiny eggs measure
0.7-0.9 mm in diameter and their creamy colour make them near
impossible to see among sand grains. Four weeks later the eggs
hatch and the 5 mm long larval sand lance join the plankton.
At about 20 mm in length, the sandlance are quite mobile and
they begin to form into schools and take on the silvery blue
color of the adults. Schools enter bays and inlets for the
winter and spring. Sand lance feed in open water during the
day and burrow into sand at night to avoid predation. During
the day, their schools are attacked from below by dogfish,
salmon and sea lions that drive the schools into tight
defensive balls. From above, flocks of gulls, cormorants,
murres and auklets descend on the balls of fish.
Sand
Lance
Conservation
There is little commercial interest in the sand lance and no
direct threats. However, there is concern that the species is
susceptible to oil spills and destruction of beaches where it
lays its eggs (Golet et al. 2002). The spawning habitat of
sand lance in Puget Sound, Washington is considered a "marine
habitat of special concern" in the Washington Administrative
Code (WAC) Hydraulic Code Rules.
References
Bertram, D.F. and G.W. Kaiser. 1993. Rhinoceros Auklet
nestling diet may gauge Pacific sand lance recruitment.
Canadian Journal of Fisheries and Aquatic Sciences 50:
1908-1915.
Golet, G.H, P. E. Seiser, D. McGuire, D. D.
Roby, J. B. Fischer, K. J. Kuletz, D. B. Irons, T. A. Dean, S.
C. Jewett, S. H. Newman. 2002. Long-term direct and indirect
effects of the 'Exxon Valdez' oil spill on pigeon guillemots
in Prince William Sound, Alaska . Marine Progress Series 241:
287-304.
Hart, J. L. 1973. Pacific fishes of Canada. Fisheries Research
Board of Canada, Ottawa.
|
