State of the Bay Report 2010-Final - Anchor Environmental

Anchor Environmental
Bay or sites within Big Bay (Figure 10.6). Although the average densities of these more common
species are variable, the differences between Small Bay and most Big Bay sites are up to an order of
magnitude and are significant (more than two standard errors) (Figure 10.6).
The densities of silverside, harders and white stump within Big Bay were highest at the Sea
Farm Dam site and generally higher than at the two North Bay sites (Figure 10.6). With the
exception of the North Bay, Strandloper and Small craft sites, 2010 sampling revealed a significant
reduction from the long term average in estimated abundance of white stumpnose at all other sites.
The density of the other species in Small Bay and Bog Bay was comparable to historical levels at
most sites.
In the earlier surveys, most sites within the Lagoon had lower estimate fish abundance than
that recorded in Small Bay and had similar fish densities to those found at the Big Bay sites (Figure
10.6 & Figure 10.7). However, the 2010 densities of harders and white stump were at four of the
five lagoon sites the highest yet recorded, and comparable to and/or greater than those recorded at
sites in Small Bay and Big Bay.
Figure 10.6. Average abundance of the four most common fish species at each of the sites sampled within
Small Bay and Big Bay during the earlier surveys (1994, 2005, 2007-2009) and during the 2010
survey. Errors bars show plus 1 Standard error. Note the scale change on vertical axis shows a
maximum of either 1 or 3 fish.m -2 .
State of the Bay 2010: Saldanha Bay and Langebaan Lagoon 228