appendix b final 2008 biological surveys of los angeles and long ...

3.0 Adult and Juvenile Fishes
species were subsampled using the same methods described above for lampara sampling.
Macroinvertebrates collected from trawl surveys were identified to the lowest practicable taxon,
counted, and an aggregate weight determined by species.
Identification of invertebrates was aided by a combination of photography and collection of
voucher specimens for taxa that could not be identified in the field. Voucher specimens were
preserved as noted for the benthic collections and final identifications, based on photographs
and/or voucher specimens, were made by taxonomic specialists.
3.2.3 Shallow Subtidal (Beach Seine) Fishes
Fish sampling in shallow-water sandy habitats was conducted
using a 15.2 m long by 1.8 m deep beach seine net. The net
had 0.6 cm mesh wings with a bag end of 0.3 cm mesh. The
fish catch was processed in the field. Every specimen was
identified and counted, except when abundant species were
encountered. If more than 30 individuals from one species
was collected, the same protocols used for trawl and lampara
sampling were followed (see Section 3.2.1). After field
processing was completed, all specimens were immediately
returned to the water to reduce potential mortality.
3.2.4 Data Analysis
All fish data were entered into a database which included unique species codes, count, length,
and weight data. In addition, the fish database was subjected to standardized quality assurance
routines. Consistent with the previous baseline survey analyses, abundance and biomass
values in this report are presented as catch per unit effort (CPUE), that is, catch in one set of
the lampara net, otter trawl, or beach seine. Fish length data were standardized to onecentimeter
size classes.
Community measures of species richness and diversity were calculated using CPUE values and
included number of species, Shannon-Wiener diversity, Margalef diversity, and Dominance.
Diversity indices and Dominance were calculated using the following formulas:
• Number of species or unique taxa;
• Shannon-Wiener diversity: -Σp i X ln(p i ), where p i is the count for species i;
• Margalef diversity: (S-1)/ln(n), where S is the number of taxa, and n is the number of
individuals; and
• Dominance: number of species comprising 75% of the total count of the sample.
Analysis of variance (ANOVA) was performed on log-transformed (natural log = ln) abundance
and biomass data to determine whether there were significant differences in catch between day
and night and/or among seasons. ANOVA was also used to test for seasonal and diurnal
differences in catches.
2008 Biological Surveys of Los Angeles and Long Beach Harbors 3–3
April 2010